Signal transmission device

Abstract

A signal transmission device according to the present invention is provided with: a first chip including a first transformer; a second chip; a plurality of first lead terminals; a plurality of second lead terminals; an inter-chip wire electrically connecting the first chip and the second chip; and first lead wires individually connecting the first chip to the plurality of first lead terminals. The inter-chip wire is formed from a material that includes gold. The first lead wires are formed from a material that includes copper or aluminum.

Description

signal transmission device

[0001] The present disclosure relates to a signal transmission device.

[0002] A signal transmission device has been known that includes a first die pad, a second die pad disposed at a distance from the first die pad, a first chip and a transformer chip mounted on the first die pad, a second chip mounted on the second die pad, and a sealing resin that seals the die pads and chips (see, for example, Patent Document 1). In such a signal transmission device, the first chip and the transformer chip are electrically connected by a wire, and the transformer chip and the second chip are electrically connected by another wire.

[0003] Japanese Patent Application Laid-Open No. 2016-207714

[0004] From the viewpoint of the insulation reliability of signal transmission devices, it is desired to inspect with higher accuracy the shape and height of inter-chip wires that electrically connect adjacent chips.

[0005] a first die pad on which the first chip is mounted; a second die pad disposed apart from the first die pad in a first direction and on which the second chip is mounted; a plurality of first lead terminals disposed on the opposite side of the first die pad from the second die pad in the first direction and arranged in a second direction orthogonal to the first direction in a plan view; a plurality of second lead terminals disposed on the opposite side of the second die pad from the first die pad in the first direction and arranged in the second direction; inter-chip wires electrically connecting the first chip and the second chip; and first lead wires individually connecting the first chip and the plurality of first lead terminals; The second die pads are arranged spaced apart from each other in a first direction, the multiple first lead terminals are arranged on the opposite side of the first die pad from the second die pad in the second direction, the first lead terminals of the multiple first lead terminals arranged at both ends in the first direction are connected to the first die pad in a state facing both ends of the first die pad in the second direction, the multiple second lead terminals are arranged on the opposite side of the second die pad from the first die pad in the second direction, and the second lead terminals of the multiple second lead terminals arranged at both ends in the first direction are connected to the second die pad in a state facing both ends of the second die pad in the first direction, the inter-chip wire is formed of a material containing gold, and the first lead wire is formed of a material containing copper or aluminum.

[0006] According to the signal transmission device, the wire height of the inter-chip wires can be inspected with higher accuracy.

[0007] FIG. 1 is a perspective view of a signal transmission device of a first embodiment. FIG. 2 is a side view of the signal transmission device of FIG. 1. FIG. 3 is a side view of the signal transmission device of FIG. 1 viewed from a different direction than FIG. 2. FIG. 4 is an enlarged view of a first lead terminal and its periphery of FIG. 3. FIG. 5 is an enlarged view of an outer lead end face of the first lead terminal of FIG. 4. FIG. 6 is a side view of the signal transmission device mounted on a circuit board. FIG. 7 is a schematic plan view showing the internal configuration of the signal transmission device of FIG. 1. FIG. 8 is an enlarged view of the first lead terminal and its periphery of FIG. 7. FIG. 9 is a schematic cross-sectional view of a portion of a wire connection portion of the first lead terminal. FIG. 10 is an enlarged view of the second lead terminal and its periphery of FIG. 7. FIG. 11 is a schematic cross-sectional view of a portion of a wire connection portion of the second lead terminal. FIG. 12 is an enlarged view of the inter-chip wire and its periphery of FIG. 7. FIG. 13 is a perspective view showing an enlarged structure of a portion of a second die pad wire. FIG. 14 is a circuit diagram of the signal transmission device of the first embodiment. FIG. 15 is a schematic plan view showing an example of the internal structure of a first chip in the signal transmission device of the first embodiment. FIG. 16 is an enlarged view of an insulating transformer region in the first chip of FIG. 15. FIG. 17 is a schematic plan view showing an example of the internal structure of a first chip at a position different in the thickness direction of the first chip from that of FIG. 15. FIG. 18 is an enlarged view of the insulating transformer region in the first chip of FIG. 17. FIG. 19 is a cross-sectional view of the first chip taken along line F19-F19 in FIG. 15. FIG. 20 is an enlarged view of a portion of the first chip of FIG. 19. FIG. 21 is an enlarged view of the conductor wires of the first front-side coil in the first chip of FIG. 20. FIG. 22 is an enlarged view of the conductor wires of the first back-side coil in the first chip of FIG. 20. FIG. 23 is a cross-sectional view of a portion of the circuit region of the first chip. FIG. 24 is an enlarged view of the first via and its periphery in FIG. 23. FIG. 25 is an enlarged plan view of the first lead terminal and its periphery in a signal transmission device of the second embodiment. Fig. 26 is an enlarged plan view of a second lead terminal and its periphery in the signal transmission device of the second embodiment, Fig. 27 is an enlarged plan view of a first lead terminal and its periphery in the signal transmission device of the third embodiment, and Fig. 28 is an enlarged plan view of a second lead terminal and its periphery in the signal transmission device of the third embodiment.FIG. 29 is an enlarged plan view of a first lead terminal and its periphery in the signal transmission device of the fourth embodiment. FIG. 30 is an enlarged plan view of a second lead terminal and its periphery in the signal transmission device of the fourth embodiment. FIG. 31 is a perspective view showing an enlarged structure of a portion of a second lead wire. FIG. 32 is a plan view schematically showing the internal structure of a signal transmission device of the fifth embodiment. FIG. 33 is an enlarged view of an inter-chip wire and its periphery in a signal transmission device of the sixth embodiment. FIG. 34 is a schematic cross-sectional view of a first chip and a first die pad in a signal transmission device of the seventh embodiment. FIG. 35 is a schematic cross-sectional view of the first chip and the first die pad cut in a direction different from that in FIG. 34. FIG. 36 is a schematic cross-sectional view of a second chip and a second die pad. FIG. 37 is a schematic cross-sectional view of the second chip and the second die pad cut in a direction different from that in FIG. 36. FIG. 38 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the seventh embodiment. FIG. 39 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 38 . FIG. 40 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 39 . FIG. 41 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 40 . FIG. 42 is a plan view schematically showing the internal structure of the signal transmission device of the eighth embodiment. FIG. 43 is a perspective view of the signal transmission device of the ninth embodiment. FIG. 44 is a plan view schematically showing the internal structure of the signal transmission device of FIG. 43 . FIG. 45 is an enlarged view of the first frame and its periphery of FIG. 44 . FIG. 46 is an enlarged view of the second frame and its periphery of FIG. 44 . FIG. 47 is a schematic plan view showing an example of the internal structure of the first chip. FIG. 48 is a schematic plan view showing an example of the internal structure of the first chip at a position different from that of FIG. 47 in the thickness direction of the first chip. FIG. 49 is a circuit diagram of the signal transmission device of the ninth embodiment. Fig. 50 is an enlarged plan view of a second lead terminal and its periphery in a signal transmission device of a tenth embodiment, Fig. 51 is an enlarged plan view of a first lead terminal and its periphery in a signal transmission device of an eleventh embodiment, and Fig. 52 is an enlarged plan view of a second lead terminal and its periphery in a signal transmission device of an eleventh embodiment.FIG. 53 is an enlarged plan view of a first lead terminal and its periphery in a signal transmission device of the twelfth embodiment. FIG. 54 is an enlarged plan view of a second lead terminal and its periphery in a signal transmission device of the twelfth embodiment. FIG. 55 is a plan view schematically showing the internal structure of a signal transmission device of the thirteenth embodiment. FIG. 56 is an enlarged view of an inter-chip wire and its periphery in a signal transmission device of the fourteenth embodiment. FIG. 57 is a schematic plan view schematically showing the internal structure of a signal transmission device of the fifteenth embodiment. FIG. 58 is a schematic plan view schematically showing the internal structure of a signal transmission device of the sixteenth embodiment. FIG. 59 is an enlarged view of the first lead terminal and its periphery in FIG. 58. FIG. 60 is an enlarged view of the second lead terminal and its periphery in FIG. 58. FIG. 61 is a schematic plan view schematically showing an example of the internal structure of a second chip. FIG. 62 is a schematic plan view schematically showing an example of the internal structure of a second chip at a position different from that in FIG. 61 in the thickness direction of the second chip. FIG. 63 is a circuit diagram of a signal transmission device of a sixteenth embodiment. FIG. 64 is a plan view showing an enlargement of a first lead terminal and its periphery in a signal transmission device of a seventeenth embodiment. FIG. 65 is a plan view showing an enlargement of a second lead terminal and its periphery in a signal transmission device of a seventeenth embodiment. FIG. 66 is a plan view showing an enlargement of a first lead terminal and its periphery in a signal transmission device of an eighteenth embodiment. FIG. 67 is a plan view showing an enlargement of a second lead terminal and its periphery in a signal transmission device of an eighteenth embodiment. FIG. 68 is a plan view showing an enlargement of a first lead terminal and its periphery in a signal transmission device of a nineteenth embodiment. FIG. 69 is a plan view showing an enlargement of a second lead terminal and its periphery in a signal transmission device of a nineteenth embodiment. FIG. 70 is a plan view showing an enlargement of an inter-chip wire and its periphery in a signal transmission device of a twentieth embodiment. FIG. 71 is a schematic plan view showing an example of the internal structure of a second chip. FIG. 72 is a plan view showing an example of the internal structure of a second chip at a position different from that in FIG. 71 in the thickness direction of the second chip. Fig. 73 is a circuit diagram of a signal transmission device of a twentieth embodiment, Fig. 74 is a cross-sectional view of a signal transmission device of a twenty-first embodiment, and Fig. 75 is an enlarged view of a part of Fig. 74.FIG. 76 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the twenty-first embodiment. FIG. 77 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 76 . FIG. 78 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 77 . FIG. 79 is a cross-sectional view enlarging an isolation transformer region for the signal transmission device of the twenty-second embodiment. FIG. 80 is a cross-sectional view of a conductor and its periphery for the signal transmission device of the twenty-third embodiment. FIG. 81 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the twenty-third embodiment. FIG. 82 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 81 . FIG. 83 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 82 . FIG. 84 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 83 . FIG. 85 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 84 . FIG. 86 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 85 . FIG. 87 is a cross-sectional view of a conductor and its periphery in a signal transmission device of the 24th embodiment. FIG. 88 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the 24th embodiment. FIG. 89 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 88. FIG. 90 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 89. FIG. 91 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 90. FIG. 92 is a cross-sectional view schematically showing a part of the manufacturing process for the signal transmission device subsequent to FIG. 91. FIG. 93 is a schematic plan view showing an example of the internal structure of a first chip in a signal transmission device of a modified example. FIG. 94 is a schematic plan view showing an example of the internal structure of the first chip at a position different from that in FIG. 93 in the thickness direction of the first chip. FIG. 95 is a schematic plan view showing the internal structure of a signal transmission device of a modified example.

[0008] Hereinafter, several embodiments of a signal transmission device according to the present disclosure will be described with reference to the accompanying drawings. Note that for simplicity and clarity of description, the components shown in the drawings are not necessarily drawn to scale. Also, hatching lines may be omitted in cross-sectional views to facilitate understanding. The accompanying drawings merely illustrate embodiments of the present disclosure and should not be considered as limiting the present disclosure.

[0009] The following detailed description includes devices, systems, and methods embodying exemplary embodiments of the present disclosure. This detailed description is merely illustrative in nature and is not intended to limit the embodiments of the present disclosure or the application and uses of such embodiments.

[0010] <First Embodiment> A signal transmission device 10 according to the first embodiment will be described with reference to Figures 1 to 24. Figures 1 to 6 show the external structure of the signal transmission device 10. Figures 7 to 13 show the internal structure of the signal transmission device 10. Figure 14 shows the circuit configuration of the signal transmission device 10. Figures 15 to 24 show the internal structure of a first chip 60 (described later) of the signal transmission device 10.

[0011] [External Configuration of Signal Transmission Device] Fig. 1 shows a perspective view of the signal transmission device 10. Figs. 2 and 3 show a side view of the signal transmission device 10. Fig. 4 shows an enlarged view of a portion of a first lead terminal 18 (described later) of the signal transmission device 10.

[0012] 1, the signal transmission device 10 has a small outline package (SOP) package structure. However, the package structure of the signal transmission device 10 can be changed as desired, and may be a quad for non-lead package (QFN), dual flat package (DFP), dual inline package (DIP), quad flat package (QFP), single inline package (SIP), small outline J-leaded package (SOJ), or any of a variety of similar package structures.

[0013] As shown in FIG. 1, the signal transmission device 10 includes a sealing resin 90, a plurality of first lead terminals 11 to 18 (eight in the first embodiment) protruding from the sealing resin 90, and a plurality of second lead terminals 41 to 48 (eight in the first embodiment) protruding from the sealing resin 90.

[0014] The sealing resin 90 is formed in a rectangular plate shape. Here, in this specification, the thickness direction of the sealing resin 90 is referred to as the "Z direction," and two mutually orthogonal directions perpendicular to the Z direction are referred to as the "X direction" and the "Y direction." Furthermore, the upper side of the Z direction is referred to as the "+Z direction," and the lower side is referred to as the "-Z direction." In FIG. 1 , the front side of the X direction is referred to as the "+X direction," and the rear side is referred to as the "-X direction." In FIG. 1 , the right side of the Y direction is referred to as the "+Y direction," and the left side is referred to as the "-Y direction." Furthermore, in this specification, the term "planar view" refers to viewing the signal transmission device 10 from the thickness direction of the sealing resin 90. Unless otherwise specified, the term "planar view" refers to viewing the signal transmission device 10 from the +Z direction.

[0015] The shape of the sealing resin 90 in plan view is a rectangle with the longitudinal direction in the X direction and the lateral direction in the Y direction. In one example, the dimension of the sealing resin 90 in the X direction is about 7.5 mm, the dimension of the sealing resin 90 in the Y direction is about 6.4 mm, and the dimension (thickness) of the sealing resin 90 in the Z direction is about 2.35 mm.

[0016] As shown in FIGS. 1 to 3 , the sealing resin 90 has a sealing surface 91, a sealing back surface 92 opposite the sealing surface 91, and first to fourth sealing side surfaces 93 to 96 connecting the sealing surface 91 and the sealing back surface 92. The sealing surface 91 faces in the +Z direction, and the sealing back surface 92 faces in the −Z direction. The first sealing side surface 93 and the second sealing side surface 94 constitute both end surfaces of the sealing resin 90 in the X direction, and the third sealing side surface 95 and the fourth sealing side surface 96 constitute both end surfaces of the sealing resin 90 in the Y direction. The first sealing side surface 93 faces in the +X direction, and the second sealing side surface 94 faces in the −X direction. The third sealing side surface 95 faces in the +Y direction, and the fourth sealing side surface 96 faces in the −Y direction.

[0017] 1, a recess 91A is formed in the sealing surface 91. The recess 91A is circular in plan view. The recess 91A is recessed in a curved concave shape from the sealing surface 91. The recess 91A is formed in a portion of the sealing surface 91 that is closer to the first sealing side surface 93 and the fourth sealing side surface 96. The recess 91A serves as a marker for distinguishing the first lead terminals 11 to 18 from the second lead terminals 41 to 48.

[0018] As shown in FIG. 3 , the first sealing side surface 93 includes a first front side surface 93A continuous with the sealing surface 91, a first back side surface 93B continuous with the sealing back surface 92, and a first central side surface 93C. The second sealing side surface 94 includes a second front side surface 94A continuous with the sealing surface 91, a second back side surface 94B continuous with the sealing back surface 92, and a second central side surface 94C. The first front side surface 93A and the second front side surface 94A are inclined away from each other as they extend from the sealing surface 91 toward the sealing back surface 92. A sloped surface 93AA is formed at the connection between the first front side surface 93A and the sealing surface 91. The angle formed by the sloped surface 93AA and the Z direction is larger than the angle formed by the first front side surface 93A and the Z direction. The angle formed by the sloped surface 93AA and the Z direction is, for example, 45°. The connection portion between the second front surface side surface 94A and the sealing surface 91 is curved. The first back surface side surface 93B and the second back surface side surface 94B are inclined in directions away from each other as they move from the sealing back surface 92 to the sealing surface 91. The connection portions between the first back surface side surface 93B and the second back surface side surface 94B and the sealing back surface 92 are curved. The first central side surface 93C is formed between the first front surface side surface 93A and the first back surface side surface 93B in the Z direction. The first central side surface 93C is connected to both the first front surface side surface 93A and the first back surface side surface 93B. The first central side surface 93C is formed as a flat surface along, for example, the YZ plane. The second central side surface 94C is formed between the second front surface side surface 94A and the second back surface side surface 94B in the Z direction. The second central side surface 94C is connected to both the second front surface side surface 94A and the second back surface side surface 94B. The second central side surface 94C is formed as a flat surface along the YZ plane, for example.

[0019] As shown in FIG. 2 , the third sealing side surface 95 includes a third front surface side surface 95A continuous with the sealing surface 91, a third back surface side surface 95B continuous with the sealing back surface 92, and a third central side surface 95C. The fourth sealing side surface 96 includes a fourth front surface side surface 96A continuous with the sealing surface 91, a fourth back surface side surface 96B continuous with the sealing back surface 92, and a fourth central side surface 96C. The third front surface side surface 95A and the fourth front surface side surface 96A are inclined in directions away from each other as they extend from the sealing surface 91 toward the sealing back surface 92. The connection portions between the third front surface side surface 95A and the fourth front surface side surface 96A and the sealing surface 91 are curved. The third back surface side surface 95B and the fourth back surface side surface 96B are inclined in directions away from each other as they extend from the sealing back surface 92 toward the sealing surface 91. The connection portions between the third back surface side surface 95B and the fourth back surface side surface 96B and the sealing back surface 92 are curved. The third central side surface 95C is connected to both the third front surface side surface 95A and the third back surface side surface 95B. The third central side surface 95C is formed, for example, as a flat surface along the XZ plane. The fourth central side surface 96C is formed between the fourth front surface side surface 96A and the fourth back surface side surface 96B in the Z direction. The fourth central side surface 96C is connected to both the fourth front surface side surface 96A and the fourth back surface side surface 96B. The fourth central side surface 96C is formed, for example, as a flat surface along the XZ plane.

[0020] The sealing resin 90 is formed, for example, by transfer molding. In one example, the third sealing side surface 95 has a trace (not shown) of the gate of a molding die. This trace is formed when a resin portion located at the gate of the molding die is separated from the sealing resin 90. The trace is formed, for example, on a third central side surface 95C of the third sealing side surface 95. In one example, as shown in FIG. 3 , the third central side surface 95C is partitioned into three regions R1 to R3 in the X direction. The regions R1 to R3 are regions of equal size. Region R1 is a region of the third central side surface 95C closer to the first sealing side surface 93, region R3 is a region of the third central side surface 95C closer to the second sealing side surface 94, and region R2 is a region between regions R1 and R3 in the X direction. The trace may be provided in region R1. Alternatively, the trace may be provided in region R2. The trace may be provided in region R3.

[0021] The gate trace of the molding die may be formed on the fourth sealing side surface 96 instead of the third sealing side surface 95. In this case, the gate trace is also formed on, for example, the fourth central side surface 96C of the fourth sealing side surface 96.

[0022] The surface roughness Rz of each of the sealing surface 91, sealing back surface 92, and first to fourth sealing side surfaces 93 to 96 of the sealing resin 90 is, for example, 5 μm or more and 20 μm or less. In the first embodiment, the surface roughness Rz across the entire surface of each of the sealing surface 91 and sealing back surface 92 is, for example, 5 μm or more and 20 μm or less. Furthermore, the surface roughness Rz across the entire surface of each of the first to fourth front side surfaces 93A to 96A and the first to fourth back side surfaces 93B to 96B of the first to fourth sealing side surfaces 93 to 96 is, for example, 5 μm or more and 20 μm or less. Here, the surface roughness Rz can be expressed as the sum of the height of the highest peak and the depth of the deepest valley of the profile curve over the reference length. In one example, the sealing surface 91, sealing back surface 92, and first to fourth sealing side surfaces 93 to 96 are subjected to a surface roughening treatment, thereby making each surface roughness Rz, for example, 5 μm or more and 20 μm or less. An example of the surface roughening treatment is shot blasting.

[0023] In one example, the surface roughness Rz of each of the sealing surface 91, the sealing back surface 92, and the first to fourth sealing side surfaces 93 to 96 is, for example, 8 μm or more. In one example, the surface roughness Rz of each of the sealing surface 91, the sealing back surface 92, and the first to fourth sealing side surfaces 93 to 96 is, for example, 8 μm or more and 20 μm or less.

[0024] In one example, the surface roughness Rz of the sealing surface 91 and the sealing back surface 92, and the first to fourth front side surfaces 93A to 96A and the first to fourth back side surfaces 93B to 96B may be greater than that of the first to fourth central side surfaces 93C to 95C. In one example, the surface roughness Rz of the sealing surface 91 and the sealing back surface 92, and the first to fourth front side surfaces 93A to 96A and the first to fourth back side surfaces 93B to 96B may be greater than the surface roughness Rz of the surfaces that form the recess 91A.

[0025] In the first embodiment, the surface roughness Rz of the sealing surface 91, the sealing back surface 92, and the first to fourth sealing side surfaces 93 to 96 was 5 μm or more and 20 μm or less, but this is not limited thereto. In one example, the surface roughness Rz of each of the third sealing side surface 95 and the fourth sealing side surface 96 may be less than 5 μm or greater than 20 μm. In another example, the surface roughness Rz of each of the first sealing side surface 93 and the second sealing side surface 94 may be less than 5 μm or greater than 20 μm. In another example, the surface roughness Rz of each of the first to fourth sealing side surfaces 93 to 96 may be less than 5 μm or greater than 20 μm. In another example, the surface roughness Rz of the sealing surface 91 may be less than 5 μm or greater than 20 μm. In short, it is sufficient that the surface roughness Rz of at least one of the sealing front surface 91, the sealing back surface 92, and the first to fourth sealing side surfaces 93 to 96 is 5 μm or more and 20 μm or less.

[0026] The sealing resin 90 is made of an insulating material. One example of the insulating material is black epoxy resin. The sealing resin 90 contains sulfur (S) as an additive. By including sulfur, the sealing resin 90 can enhance the adhesive strength between the sealing resin 90 and the first frame 10A and the second frame 10B, which will be described later. On the other hand, if the sealing resin 90 contains sulfur, there is a risk of sulfide corrosion of copper-based components in the signal transmission device 10. The sulfur concentration in the sealing resin 90 is set in consideration of the balance between improving the adhesive strength between the sealing resin 90 and the first frame 10A and the second frame 10B and suppressing sulfide corrosion. In one example, the sulfur concentration in the sealing resin 90 is set to 300 μg / g or less.

[0027] As shown in FIG. 1 , the first lead terminals 11 to 18 include first outer lead portions 11B to 18B that protrude outward from the sealing resin 90. In a plan view, the first outer lead portions 11B to 18B protrude from the first sealing side surface 93 in the +X direction. The first outer lead portions 11B to 18B are arranged spaced apart from one another in the Y direction. The first outer lead portions 11B to 18B can be said to be arranged in the short-side direction of the sealing resin 90. The first outer lead portions 11B to 18B are arranged in the following order from the fourth sealing side surface 96 to the third sealing side surface 95: 11B, 12B, 13B, 14B, 15B, 16B, 17B, and 18B. In other words, the Y direction can be said to be the arrangement direction of the first outer lead portions 11B to 18B. In other words, the Y direction can be said to be the arrangement direction of the first lead terminals 11 to 18. In the first embodiment, the first outer lead portions 11B to 18B have the same shape.

[0028] The second lead terminals 41 to 48 include second outer lead portions 41B to 48B that protrude outward from the sealing resin 90. In a plan view, the second outer lead portions 41B to 48B protrude from the second sealing side surface 94 in the -X direction. The second outer lead portions 41B to 48B are arranged spaced apart from one another in the Y direction. The second outer lead portions 41B to 48B can be said to be arranged in the short-side direction of the sealing resin 90. The second outer lead portions 41B to 48B are arranged in the following order from the third sealing side surface 95 to the fourth sealing side surface 96: 41B, 42B, 43B, 44B, 45B, 46B, 47B, and 48B. In other words, the Y direction can be said to be the arrangement direction of the second outer lead portions 41B to 48B. In other words, the Y direction can be said to be the arrangement direction of the second lead terminals 41 to 48. In the first embodiment, the second outer lead portions 41B to 48B have the same shape.

[0029] The widths (size in the Y direction) of the first outer lead portions 11B to 18B and the widths (size in the Y direction) of the second outer lead portions 41B to 48B are equal to each other. The widths of the first outer lead portions 11B to 18B and the second outer lead portions 41B to 48B are, for example, approximately 0.33 mm. The pitch of the first outer lead portions 11B to 18B and the pitch of the second outer lead portions 41B to 48B are equal to each other. Here, the pitch of the first outer lead portions 11B to 18B can be defined by the center-to-center distance between two of the first outer lead portions 11B to 18B adjacent to each other in the Y direction. The pitch of the second outer lead portions 41B to 48B can be defined by the center-to-center distance between two of the second outer lead portions 41B to 48B adjacent to each other in the Y direction. The pitch of the first outer lead portions 11B to 18B and the pitch of the second outer lead portions 41B to 48B are each, for example, about 0.65 mm.

[0030] 3, the shape of the first outer lead portion 18B and the shape of the second outer lead portion 41B when viewed from the Y direction are the same. Therefore, it can be said that the shapes of the first outer lead portions 11B to 18B and the shapes of the second outer lead portions 41B to 48B are the same.

[0031] The configuration of the first outer lead portions 11B to 18B will be described below. The detailed configuration of the first outer lead portion 18B will be described below, and a detailed description of the configuration of the first outer lead portions 11B to 17B will be omitted.

[0032] The first outer lead portion 18B includes a protruding portion 18P extending in the +X direction from the first sealing side surface 93, an intermediate portion 18Q extending in the -Z direction from the protruding portion 18P, and a connecting portion 18R extending in the +X direction from the intermediate portion 18Q. A curved first bend is formed between the protruding portion 18P and the intermediate portion 18Q, and a curved second bend is formed between the intermediate portion 18Q and the connecting portion 18R. The connecting portion 18R may be inclined toward the -Z direction as it approaches the +X direction. The acute angle formed by the connecting portion 18R and the X direction is, for example, greater than 0° and equal to or less than 8°.

[0033] As shown in Fig. 4, the first outer lead portion 18B includes an outer lead body 20A made of a metal material. Examples of metal materials include copper and aluminum. The outer lead body 20A has an outer lead surface 21A, an outer lead back surface 22A opposite to the outer lead surface 21A, a pair of outer lead side surfaces 23A (see Fig. 5) connecting the outer lead surface 21A and the outer lead back surface 22A, and an outer lead end surface 24A. The outer lead end surface 24A forms the tip surface of the connection portion 18R.

[0034] 5, the pair of outer lead side surfaces 23A are formed in a curved concave shape. In one example, the deepest position of the curved concave outer lead side surface 23A (the position where the pair of outer lead side surfaces 23A are closest to each other in the Y direction) is closer to the outer lead back surface 22A than the center in the Z direction of the outer lead end surface 24A.

[0035] The outer lead body 20A has a backside curved portion 25 formed at the connection portion between the outer lead back surface 22A and the outer lead side surface 23A. The backside curved portion 25 curves upward (in the +Z direction) as it moves outward in the width direction (Y direction) of the outer lead body 20A. Therefore, both ends of the outer lead back surface 22A in the Y direction are curved upward (in the +Z direction) as they move toward the pair of outer lead side surfaces 23A.

[0036] 4 and 5, the first outer lead portion 18B includes a plating layer 26 that covers the outer lead body 20A. More specifically, the plating layer 26 covers the entire surfaces of the outer lead front surface 21A, the outer lead back surface 22A, and the outer lead side surface 23A, as well as a part of the outer lead end surface 24A.

[0037] 5, the plating layer 26 includes an end-face plating layer 27 that covers the outer lead end face 24A continuously from the outer lead back surface 22A toward the outer lead front surface 21A. The end-face plating layer 27 is located apart in the Z direction from the edge of the outer lead end face 24A on the outer lead front surface 21A side. Therefore, the outer lead end face 24A is divided into a region covered by the end-face plating layer 27 and a main body exposed region 28 that is not covered by the end-face plating layer 27. In the main body exposed region 28, the outer lead main body 20A is exposed.

[0038] The end surface plating layer 27 extends from the outer lead back surface 22A to a position closer to the outer lead front surface 21A than the center of the outer lead end surface 24A in the Z direction. In one example, the end surface plating layer 27 covers approximately two-thirds of the outer lead end surface 24A in the Z direction. The leading edge 27A of the end surface plating layer 27 has a shape that becomes uneven in the Z direction as it extends in the Y direction. In one example, the leading edge 27A of the end surface plating layer 27 has a recess 27B near the center in the Y direction.

[0039] The shape of the leading edge 27A of the end surface plating layer 27 can be changed as desired. For example, the leading edge 27A of the end surface plating layer 27 may include a plurality of recesses 27B. For another example, the recesses 27B may be omitted from the leading edge 27A of the end surface plating layer 27.

[0040] Furthermore, the position of the leading edge 27A of the end surface plating layer 27 in the Z direction can be changed as desired. In one example, the end surface plating layer 27 may cover approximately one-half of the outer lead end surface 24A in the Z direction. In another example, the end surface plating layer 27 may cover approximately one-quarter of the outer lead end surface 24A in the Z direction. In another example, the end surface plating layer 27 may cover approximately three-quarters of the outer lead end surface 24A in the Z direction. In this way, the end surface plating layer 27 may cover a range of at least one-quarter but not more than three-quarters of the outer lead end surface 24A in the Z direction.

[0041] The configuration of the second outer lead portions 41B to 48B will be described below. The detailed configuration of the second outer lead portion 41B will be described below, and a detailed description of the configuration of the second outer lead portions 42B to 48B will be omitted.

[0042] 3, the second outer lead portion 41B includes a protruding portion 41P extending in the −X direction from the second sealing side surface 94, an intermediate portion 41Q extending in the −Z direction from the protruding portion 41P, and a connecting portion 41R extending in the −X direction from the intermediate portion 41Q. A curved first bend is formed between the protruding portion 41P and the intermediate portion 41Q, and a curved second bend is formed between the intermediate portion 41Q and the connecting portion 41R. The connecting portion 41R may be inclined toward the −Z direction as it approaches the −X direction. The acute angle formed by the connecting portion 41R and the X direction is, for example, greater than 0° and equal to or less than 8°.

[0043] Like the first outer lead portion 18B, the second outer lead portion 41B includes an outer lead body 20A and a plating layer 26 covering the outer lead body 20A (see FIG. 4 for both). Also, like the first outer lead portion 18B, the plating layer 26 of the second outer lead portion 41B includes an end face plating layer 27 (see FIG. 4).

[0044] A method for forming such an end face plating layer 27 is described below. A first lead frame (not shown) constituting the first outer lead portion 18B and a second lead frame (not shown) constituting the second outer lead portion 41B are cut using a die (punch). Cutting with a die can be performed, for example, on the first lead frame and the second lead frame connected to a frame. Then, the outer leads 11B to 18B, 41B to 48B formed by cutting are formed.

[0045] Here, both the first lead frame and the second lead frame before being cut by the mold include an outer lead body 20A and a plating layer 26 covering the outer lead surface 21A, the outer lead back surface 22A, and a pair of outer lead side surfaces 23A.

[0046] The mold cuts both the first lead frame and the second lead frame, for example, in the +Z direction, thereby forming the first outer lead portion 18B and the second outer lead portion 41B, each including the outer lead end surface 24A.

[0047] The corners of the cut portion of the die are rounded and curved. In other words, the corners are R-chamfered. When a die having such corners is moved, for example, in the +Z direction so as to cut both the first lead frame and the second lead frame, plating layer 26 on outer lead back surface 22A is pulled toward outer lead front surface 21A, forming end surface plating layer 27 on outer lead end surface 24A.

[0048] Furthermore, because the end surface plating layer 27 is formed on both the first outer lead portion 18B and the second outer lead portion 41B, when the signal transmission device 10 is mounted on a circuit board PCB using a conductive bonding material SD such as solder paste or silver (Ag) paste, as shown in FIG. 6 , the bonding area between the first outer lead portion 18B and the second outer lead portion 41B and the conductive bonding material SD can be increased. More specifically, the outer lead back surface 22A of the connection portion 18R of the first outer lead portion 18B, the pair of outer lead side surfaces 23A (see FIG. 5 ), and the outer lead back surface 22A at the end of the intermediate portion 18Q on the connection portion 18R side are all bonded to the conductive bonding material SD. In addition, the end surface plating layer 27 of the first outer lead portion 18B bonds the outer lead end surface 24A (see FIG. 5 ) of the first outer lead portion 18B to the conductive bonding material SD. The bonding area between the first outer lead portion 18B and the conductive bonding material SD is increased by the bonding area between this end-face plating layer 27 and the conductive bonding material SD. The outer lead back surface 22A of the connection portion 41R of the second outer lead portion 41B, the pair of outer lead side surfaces 23A, and the outer lead back surface 22A of the end of the intermediate portion 41Q on the connection portion 41R side are all bonded to the conductive bonding material SD. Additionally, the end-face plating layer 27 of the second outer lead portion 41B bonds the outer lead end surface 24A of the second outer lead portion 41B to the conductive bonding material SD. The bonding area between the second outer lead portion 41B and the conductive bonding material SD is increased by the bonding area between this end-face plating layer 27 and the conductive bonding material SD. Additionally, the conductive bonding material SD bonded to the end-face plating layer 27 of each of the first outer lead portion 18B and the second outer lead portion 41B forms a fillet. Although not shown in Figure 6, the bonding area with the conductive bonding material SD is also increased and fillets are formed for the first outer lead portions 11B to 17B and the second outer lead portions 42B to 48B (both see Figure 1).

[0049] [Internal Structure of Signal Transmission Device] Fig. 7 shows the overall internal structure of the signal transmission device 10. In Fig. 7, Fig. 8, and Fig. 10, the sealing resin 90 is indicated by a two-dot chain line to facilitate understanding of the drawings.

[0050] 7, signal transmission device 10 includes a first frame 10A, a second frame 10B, a first chip 60 mounted on first frame 10A, and a second chip 70 mounted on second frame 10B. Sealing resin 90 seals first chip 60 and second chip 70 and also partially seals first frame 10A and second frame 10B.

[0051] The first frame 10A includes first lead terminals 11 to 18. The first frame 10A further includes a first die pad 30. The first lead terminals 11 to 18 and the first die pad 30 are formed of the same metal material. Examples of the metal material include copper and aluminum.

[0052] The first lead terminals 11 and 18 arranged at both ends in the Y direction are connected to the first die pad 30. In one example, the first lead terminals 11 and 18 are integrated with the first die pad 30. The first lead terminals 12 to 17 arranged between the first lead terminal 11 and the first lead terminal 18 in the Y direction are arranged closer to the first sealing side surface 93 than the first die pad 30 and spaced apart from the first die pad 30 in the X direction.

[0053] The first die pad 30 is disposed closer to the first sealing side surface 93 than the center of the sealing resin 90 in the X direction. The first die pad 30 has a size in the Y direction such that it overlaps with all of the first lead terminals 11 to 18 when viewed from the X direction. In the first embodiment, the size of the first die pad 30 in the Y direction is larger than the distance in the Y direction between the edge of the first lead terminal 11 on the fourth sealing side surface 96 side and the edge of the first lead terminal 18 on the third sealing side surface 95 side.

[0054] The first chip 60 mounted on the first die pad 30 is formed in a flat plate shape. In a plan view, the first chip 60 has a rectangular shape with the X direction as the short side and the Y direction as the long side. The first chip 60 is mounted on the first die pad 30 with a first conductive bonding material SD1. More specifically, the first chip 60 is die-bonded to the first die pad 30. The first chip 60 is disposed at the center of the first die pad 30 in the X direction and the center of the first die pad 30 in the Y direction. Note that the position of the first chip 60 relative to the first die pad 30 can be changed as desired.

[0055] The second frame 10B is disposed apart from the first frame 10A in the X direction. That is, in the first embodiment, the X direction can be said to be the arrangement direction of the first frame 10A and the second frame 10B. The second frame 10B includes second lead terminals 41 to 48. The second frame 10B further includes a second die pad 50. The second lead terminals 41 to 48 and the second die pad 50 are formed of the same metal material. Examples of metal materials include copper and aluminum. In one example, the second lead terminals 41 to 48 and the second die pad 50 are formed of the same metal material as the first lead terminals 11 to 18 and the first die pad 30.

[0056] The second lead terminals 41, 48 arranged at both ends in the Y direction are connected to the second die pad 50. In one example, the second lead terminals 41, 48 and the second die pad 50 are integrated. The second lead terminals 42 to 47 arranged between the second lead terminal 41 and the second lead terminal 48 in the Y direction are arranged closer to the second sealing side surface 94 than the second die pad 50 and are spaced apart from the second die pad 50.

[0057] The second die pad 50 is disposed in the X direction closer to the second sealing side surface 94 relative to the first die pad 30 and spaced apart from the first die pad 30. In other words, the X direction can be considered to be the arrangement direction of the first die pad 30 and the second die pad 50. The first die pad 30 and the second die pad 50 can also be considered to be arranged in the longitudinal direction of the sealing resin 90. The second die pad 50 is disposed in the X direction closer to the second sealing side surface 94 than the center of the sealing resin 90. The second die pad 50 has a size in the Y direction such that it overlaps with all of the second lead terminals 41 to 48 when viewed from the X direction. In the first embodiment, the size of the second die pad 50 in the Y direction is greater than the distance between the edge of the second lead terminal 41 on the third sealing side surface 95 side and the edge of the second lead terminal 48 on the fourth sealing side surface 96 side. In the first embodiment, the size of the second die pad 50 in the Y direction is equal to the size of the first die pad 30 in the Y direction. As shown in FIG. 7, in the first embodiment, the shape of the first frame 10A and the shape of the second frame 10B are symmetrical with respect to an imaginary line along the Y direction at the center of the sealing resin 90 in the X direction.

[0058] The second chip 70 mounted on the second die pad 50 is formed in a flat plate shape. In a plan view, the second chip 70 has a rectangular shape with the X direction as the short side and the Y direction as the long side. The size of the second chip 70 in the X direction is larger than the size of the first chip 60 in the X direction. The size of the second chip 70 in the Y direction is larger than the size of the first chip 60 in the Y direction. The second chip 70 is mounted on the second die pad 50 by a second conductive bonding material SD2. More specifically, the second chip 70 is die-bonded to the second die pad 50. Note that, for example, solder paste or silver paste is used as both the first conductive bonding material SD1 and the second conductive bonding material SD2.

[0059] The second chip 70 is disposed at the center in the X direction and the center in the Y direction of the second die pad 50. The second chip 70 is disposed at a position overlapping the first chip 60 when viewed from the X direction. In the first embodiment, the center position in the Y direction of the second chip 70 and the center position in the Y direction of the first chip 60 are the same position in the Y direction. Note that the position of the second chip 70 relative to the second die pad 50 can be changed as desired.

[0060] The signal transmission device 10 further includes conductive members 10D and 10E. The conductive members 10D and 10E are formed, for example, from the same metal material as the first frame 10A and the second frame 10B. The conductive members 10D and 10E are arranged spaced apart from each other. Furthermore, the conductive members 10D and 10E are arranged spaced apart from both the first frame 10A and the second frame 10B. Therefore, both the conductive members 10D and 10E are in an electrically floating state.

[0061] The conductive members 10D and 10E are arranged so as to overlap each other when viewed from the Y direction. The conductive members 10D and 10E are arranged at the center of the sealing resin 90 in the Y direction. The conductive member 10D is arranged closer to the third sealing side surface 95 than the first frame 10A and the second frame 10B. The conductive member 10D is exposed from the third sealing side surface 95. More specifically, a recess 95D is formed in the portion of the third sealing side surface 95 where the conductive member 10D is exposed. The recess 95D is formed in the center of the third sealing side surface 95 in the Z direction. That is, the recess 95D is provided in the third central side surface 95C (see FIG. 2 ). The recess 95D is recessed from the third sealing side surface 95 toward the fourth sealing side surface 96. The recess 95D opens toward the +Y direction. The conductive member 10D forms the bottom surface of the recess 95D.

[0062] The conductive member 10E is disposed closer to the fourth sealing side surface 96 than the first frame 10A and the second frame 10B. The conductive member 10E is exposed from the fourth sealing side surface 96. More specifically, a recess 96D is formed in the portion of the fourth sealing side surface 96 from which the conductive member 10E is exposed. The recess 96D is formed in the center of the fourth sealing side surface 96 in the Z direction. In other words, the recess 96D is provided in the fourth central side surface 96C (see FIG. 2). The recess 96D is recessed from the fourth sealing side surface 96 toward the third sealing side surface 95. The recess 96D is open in the -Y direction. The conductive member 10E forms the bottom surface of the recess 96D.

[0063] The detailed planar structure of the first die pad 30 will be described. As shown in FIG. 7 , in a plan view, the first die pad 30 has a first tip surface 31, a first base surface 32, a first side surface 33, and a second side surface 34. The first tip surface 31 is an end surface of the first die pad 30 in the X direction that is closer to the second sealing side surface 94, and the first base surface 32 is an end surface of the first die pad 30 in the X direction that is closer to the first sealing side surface 93. The first side surface 33 is an end surface of the first die pad 30 in the Y direction that is closer to the third sealing side surface 95, and the second side surface 34 is an end surface of the first die pad 30 in the Y direction that is closer to the fourth sealing side surface 96. The first tip surface 31 is a surface that extends along the Y direction in a plan view. The first base surface 32 includes a recess 32A that is recessed from the first sealing side surface 93 toward the second sealing side surface 94 in a plan view.

[0064] The first die pad 30 further has a pair of protrusions 32B and 32C that form the recess 32A. The pair of protrusions 32B and 32C form both ends of the first die pad 30 in the Y direction. The protrusion 32B is the end of both ends of the first die pad 30 in the Y direction that is closer to the third sealing side surface 95, and the protrusion 32C is the end of both ends of the first die pad 30 in the Y direction that is closer to the fourth sealing side surface 96. Both the first side surface 33 and the second side surface 34 extend along the X direction in a plan view. The first side surface 33 forms a part of the protrusion 32B, and the second side surface 34 forms a part of the protrusion 32C.

[0065] As shown in FIG. 8 , the recess 32A includes a pair of side surfaces 32AA and a bottom surface 32AB. The pair of side surfaces 32AA extend in the X direction in a plan view. The bottom surface 32AB extends along the Y direction in a plan view. Each side surface 32AA includes a step 32AC. In a plan view, each step 32AC is formed so that the width dimension of the portions of the protrusions 32B, 32C closer to the bottom surface 32AB is larger than the width dimension of the portions of the protrusions 32B, 32C closer to the first sealing side surface 93. The first side surface 33 and the second side surface 34 form the outer surfaces of the recess 32A.

[0066] The first die pad 30 further has a first tip-side inclined portion 35, a second tip-side inclined portion 36 (both see Figure 7), a first base-side curved surface 37A, a second base-side curved surface 37B, a first recess-side curved surface 38A, and a second recess-side curved surface 38B.

[0067] 7 , the first tip-side inclined portion 35 is formed between the first tip surface 31 and the first side surface 33. In a plan view, the first tip-side inclined portion 35 is an inclined surface that inclines toward the third sealing side surface 95 as it extends from the first tip surface 31 toward the first base end surface 32. The acute angle formed by the first tip-side inclined portion 35 and the X direction is, for example, 45°.

[0068] The second tip inclined portion 36 is formed between the first tip surface 31 and the second side surface 34. In a plan view, the second tip inclined portion 36 is an inclined surface that inclines toward the fourth sealing side surface 96 as it extends from the first tip surface 31 toward the first base end surface 32. The length of the second tip inclined portion 36 in a plan view is equal to the length of the first tip inclined portion 35 in a plan view. Here, if the difference between the length of the second tip inclined portion 36 in a plan view and the length of the first tip inclined portion 35 in a plan view is, for example, within 10% of the length of the first tip inclined portion 35 in a plan view, it can be said that the length of the second tip inclined portion 36 in a plan view is equal to the length of the first tip inclined portion 35 in a plan view. The acute angle formed by the second tip inclined portion 36 and the X direction is, for example, 45°.

[0069] As shown in Fig. 8, the first base-side curved surface 37A is formed between the first base-side surface 32 and the first side surface 33. The first base-side curved surface 37A has a shape in which the portion between the first base-side surface 32 and the first side surface 33 is rounded and chamfered. The arc length of the first base-side curved surface 37A in a plan view is shorter than the length of the first tip-side inclined portion 35 (see Fig. 7) in a plan view. In other words, the length of the first tip-side inclined portion 35 in a plan view is longer than the arc length of the first base-side curved surface 37A in a plan view.

[0070] The second base-side curved surface 37B is formed between the first base-side surface 32 and the second side surface 34. The second base-side curved surface 37B has a shape in which the portion between the first base-side surface 32 and the second side surface 34 is rounded and chamfered. The arc length of the second base-side curved surface 37B in a plan view is shorter than the length of the second tip-side inclined portion 36 (see FIG. 7 ) in a plan view. In other words, the length of the second tip-side inclined portion 36 in a plan view is longer than the arc length of the second base-side curved surface 37B in a plan view.

[0071] The first recess-side curved surface 38A is formed between the side surface 32AA of the recess 32A on the protruding portion 32B side of the first base-end surface 32 and the bottom surface 32AB of the recess 32A. The first recess-side curved surface 38A has a chamfered shape where the portion between the side surface 32AA of the recess 32A on the protruding portion 32B side and the surface constituting the bottom surface 32AB of the recess 32A is rounded. The arc length of the first recess-side curved surface 38A in a plan view is equal to or greater than the arc length of the first base-end curved surface 37A in a plan view. The arc length of the first recess-side curved surface 38A in a plan view is shorter than the length of the first tip-side inclined portion 35 in a plan view. In other words, the length of the first tip-side inclined portion 35 in a plan view is longer than the arc length of the first recess-side curved surface 38A in a plan view.

[0072] The second recess-side curved surface 38B is formed between the side surface 32AA of the recess 32A on the protruding portion 32C side of the first base-end surface 32 and the surface constituting the bottom surface 32AB of the recess 32A. The second recess-side curved surface 38B has a chamfered shape where the portion between the side surface 32AA of the recess 32A on the protruding portion 32C side and the surface constituting the bottom surface 32AB of the recess 32A is rounded. The arc length of the second recess-side curved surface 38B in a plan view is equal to or greater than the arc length of the second base-end curved surface 37B in a plan view. The arc length of the second recess-side curved surface 38B in a plan view is shorter than the length of the second tip-side inclined portion 36 in a plan view. In other words, the length of the second tip-side inclined portion 36 in a plan view is longer than the arc length of the second recess-side curved surface 38B in a plan view.

[0073] The following describes the detailed configuration of each of the first lead terminals 11 to 18. As shown in Fig. 8, the first lead terminals 11 to 18 include first inner lead portions 11A to 18A provided in the sealing resin 90 and the above-mentioned first outer lead portions 11B to 18B. The following describes the configuration of the first inner lead portions 11A to 18A.

[0074] The first inner lead portion 11A is arranged closer to the fourth sealing side surface 96 than the recess 32A of the first die pad 30. The first inner lead portion 18A is arranged closer to the third sealing side surface 95 than the recess 32A of the first die pad 30. The first inner lead portions 12A to 17A are arranged in positions that overlap the recess 32A of the first die pad 30 when viewed from the X direction. The tip portions of the first inner lead portions 12A to 17A are arranged within the recess 32A of the first die pad 30.

[0075] The first inner lead portion 11A is connected to the first base end surface 32 of the first die pad 30. More specifically, the first inner lead portion 11A is connected to the protruding portion 32C of the first die pad 30. The first inner lead portion 11A extends along the X direction. The width dimension (size in the Y direction) of the first inner lead portion 11A is smaller than the width dimension (size in the Y direction) of the protruding portion 32C. The first inner lead portion 11A is positioned closer to the third sealing side surface 95 (closer to the first inner lead portion 12A) than the center of the protruding portion 32C in the Y direction.

[0076] The first inner lead portion 18A is connected to the first base end surface 32 of the first die pad 30. More specifically, the first inner lead portion 18A is connected to the protruding portion 32B of the first die pad 30. The first inner lead portion 18A extends along the X direction. The width dimension (size in the Y direction) of the first inner lead portion 18A is smaller than the width dimension (size in the Y direction) of the protruding portion 32B. The first inner lead portion 18A is disposed closer to the fourth sealing side surface 96 (closer to the first inner lead portion 17A) than the center of the protruding portion 32B in the Y direction.

[0077] The first inner lead portion 12A extends along the X direction and includes a wire connection portion 12AA and a lead connection portion 12AB extending from the wire connection portion 12AA toward the first sealing side surface 93. The lead connection portion 12AB is connected to the first outer lead portion 12B.

[0078] The wire connection portion 12AA is disposed in the recess 32A of the first die pad 30. The shape of the wire connection portion 12AA is generally rectangular in plan view. In plan view, the portion of the wire connection portion 12AA closer to the lead connection portion 12AB is formed in a tapered shape such that the width dimension (size in the Y direction) of the wire connection portion 12AA decreases toward the lead connection portion 12AB.

[0079] The lead connection portion 12AB is disposed closer to the first sealing side surface 93 than the recess 32A of the first die pad 30. The lead connection portion 12AB extends in the X direction in a plan view. In one example, the size of the lead connection portion 12AB in the Y direction is smaller than the size of the wire connection portion 12AA in the Y direction. Therefore, it can be said that the wire connection portion 12AA extends in the Y direction relative to the lead connection portion 12AB.

[0080] The first inner lead portion 13A extends along the X direction and includes a wire connection portion 13AA and a lead connection portion 13AB extending from the wire connection portion 13AA toward the first sealing side surface 93. The lead connection portion 13AB is connected to the first outer lead portion 13B.

[0081] The wire connection portion 13AA is disposed in the recess 32A of the first die pad 30. The shape of the wire connection portion 13AA is generally rectangular in plan view. In plan view, the portion of the wire connection portion 13AA closer to the lead connection portion 13AB is tapered such that the width dimension (size in the Y direction) of the wire connection portion 13AA decreases toward the lead connection portion 13AB. A corner portion of the wire connection portion 13AA closer to the bottom surface 32AB of the recess 32A and closer to the wire connection portion 12AA includes an inclined surface 13AC. In plan view, the inclined surface 13AC is inclined so as to move away from the wire connection portion 12AA in the Y direction as it moves toward the bottom surface 32AB of the recess 32A.

[0082] The lead connection portion 13AB is disposed closer to the first sealing side surface 93 than the recess 32A of the first die pad 30. The lead connection portion 13AB extends in the X direction in a plan view. In one example, the size of the lead connection portion 13AB in the Y direction is smaller than the size of the wire connection portion 13AA in the Y direction. Therefore, it can be said that the wire connection portion 13AA extends in the Y direction relative to the lead connection portion 13AB.

[0083] The first inner lead portion 14A has the same shape as the first inner lead portion 13A in a plan view. Therefore, only the general configuration of the first inner lead portion 14A will be described, and a detailed description of the configuration of the first inner lead portion 14A will be omitted.

[0084] The first inner lead portion 14A includes a wire connection portion 14AA and a lead connection portion 14AB. The wire connection portion 14AA is disposed within the recess 32A, and the lead connection portion 14AB is disposed closer to the first sealing side surface 93 than the recess 32A. The lead connection portion 14AB extends in the X direction in a plan view and is connected to the first outer lead portion 14B. The wire connection portion 14AA extends in the Y direction relative to the lead connection portion 14AB. The wire connection portion 14AA includes an inclined surface 14AC. The inclined surface 14AC has the same shape as the inclined surface 13AC of the wire connection portion 13AA.

[0085] The first inner lead portions 15A to 17A are symmetrical to the first inner lead portions 12A to 14A with respect to an imaginary line that runs along the X direction at the center of the sealing resin 90 in the Y direction. In other words, the first inner lead portion 15A is symmetrical to the first inner lead portion 14A with respect to the imaginary line. The first inner lead portion 16A is symmetrical to the first inner lead portion 13A with respect to the imaginary line. The first inner lead portion 17A is symmetrical to the first inner lead portion 12A with respect to the imaginary line. For this reason, the configuration of the first inner lead portions 15A to 17A will be described in outline, and a detailed description will be omitted.

[0086] The first inner lead portion 15A includes a wire connection portion 15AA and a lead connection portion 15AB. The wire connection portion 15AA is disposed within the recess 32A, and the lead connection portion 15AB is disposed closer to the first sealing side surface 93 than the recess 32A. The lead connection portion 15AB is connected to the first outer lead portion 15B. The wire connection portion 15AA includes an inclined surface 15AC. In a plan view, the inclined surface 15AC is inclined so as to move away from a wire connection portion 16AA (described later) in the Y direction as it approaches the bottom surface 32AB of the recess 32A.

[0087] The first inner lead portion 16A includes a wire connection portion 16AA and a lead connection portion 16AB. The wire connection portion 16AA is disposed within the recess 32A, and the lead connection portion 16AB is disposed closer to the first sealing side surface 93 than the recess 32A. The lead connection portion 16AB is connected to the first outer lead portion 16B. The wire connection portion 16AA includes an inclined surface 16AC. The inclined surface 16AC has the same shape as the inclined surface 15AC of the wire connection portion 15AA.

[0088] The first inner lead portion 17A includes a wire connection portion 17AA and a lead connection portion 17AB. The wire connection portion 17AA is disposed within the recess 32A, and the lead connection portion 17AB is disposed closer to the first sealing side surface 93 than the recess 32A. The lead connection portion 17AB is connected to the first outer lead portion 17B.

[0089] In this way, the lead connection portions 12AB to 17AB correspond to the "first portion of the first lead terminal," and the wire connection portions 12AA to 17AA correspond to the "second portion of the first lead terminal." The X direction in which the lead connection portions 12AB to 17AB extend corresponds to the "first direction," and the Y direction in which the wire connection portions 12AA to 17AA extend corresponds to the "second direction." In the first embodiment, the wire connection portions 12AA to 17AA extend in a direction perpendicular to the direction in which the lead connection portions 12AB to 17AB extend in a plan view, but this is not limited to this. The wire connection portions 12AA to 17AA may extend in any direction intersecting the direction in which the lead connection portions 12AB to 17AB extend in a plan view. In other words, the second direction is not limited to a direction perpendicular to the first direction in a plan view, but may be any direction intersecting the first direction.

[0090] Next, the detailed cross-sectional structure of the wire connection portions 12AA to 17AA of the first inner lead portions 12A to 17A will be described. Figure 9 shows the cross-sectional structure of the wire connection portion 12AA of the first inner lead portion 12A. Note that the cross-sectional structure of the wire connection portions 13AA to 17AA of the first inner lead portions 13A to 17A is similar to the cross-sectional structure of the wire connection portion 12AA, so detailed description thereof will be omitted.

[0091] 9, the inner lead body 20B of the wire connection portion 12AA has an inner lead surface 21B, an inner lead back surface 22B opposite the inner lead surface 21B, and an inner lead side surface 23B connecting the inner lead surface 21B and the inner lead back surface 22B. The inner lead side surface 23B includes a tip surface 24B facing the bottom surface 32AB (see FIG. 7) of the recess 32A of the first die pad 30. The inner lead surface 21B is the surface to which a first lead wire WB (described later) is bonded, and faces the same side as the sealing surface 91 (see FIG. 1).

[0092] In the cross-sectional view of Fig. 9, the tip surface 24B is formed as a concave shape recessed away from the first die pad 30 (see Fig. 8). The tip surface 24B is recessed from both the end on the inner lead front surface 21B side and the end on the inner lead back surface 22B side toward the center of the tip surface 24B in the Z direction. In one example, the deepest position of the concave tip surface 24B is located at a position approximately one-third of the thickness of the wire connection portion 12AA from the inner lead back surface 22B. Note that the shape of the tip surface 24B in the cross-sectional view of Fig. 9 can be changed as desired.

[0093] A plating layer 29 is formed on the inner lead surface 21B. The plating layer 29 is formed of a material containing silver, for example. The plating layer 29 is formed over substantially the entire inner lead surface 21B in the wire connection portion 12AA. The thickness of the plating layer 29 is thinner than the thickness of the inner lead body 20B in the wire connection portion 12AA.

[0094] An end surface 29A of the plating layer 29 closer to the tip surface 24B is formed at a position closer to the lead connection portion 12AB (see FIG. 8) than the edge of the inner lead surface 21B closer to the tip surface 24B. In other words, the plating layer 29 does not cover the end surface of the inner lead surface 21B closer to the tip surface 24B. As a result, the end of the inner lead surface 21B, including the edge closer to the tip surface 24B, is in contact with the sealing resin 90 (see FIG. 1).

[0095] End surface 29A of plating layer 29 is inclined so as to move away from the edge of inner lead surface 21B closer to tip surface 24B as it moves from the front surface to the back surface of plating layer 29. In one example, the distance in the X direction between the back surface of plating layer 29 and the edge of inner lead surface 21B closer to tip surface 24B is, for example, equal to or greater than the thickness of plating layer 29. Note that the distance in the X direction between the back surface of plating layer 29 and the edge of inner lead surface 21B closer to tip surface 24B can be changed as desired.

[0096] Furthermore, the plating layer 29 does not cover the tip surface 24B of the wire connection portion 12AA. Therefore, the tip surface 24B is in contact with the sealing resin 90. Furthermore, although not shown, the plating layer 29 does not cover the inner lead side surface 23B other than the tip surface 24B. Therefore, the inner lead side surface 23B is in contact with the sealing resin 90.

[0097] The configuration of the second die pad 50 will be described. As shown in FIG. 7 , in a plan view, the second die pad 50 has a second tip surface 51, a second base surface 52, a third side surface 53, and a fourth side surface 54. The second tip surface 51 is the end surface of the second die pad 50 in the X direction that is closer to the first sealing side surface 93, and the second base surface 52 is the end surface of the second die pad 50 in the X direction that is closer to the second sealing side surface 94. The third side surface 53 is the end surface of the second die pad 50 in the Y direction that is closer to the third sealing side surface 95, and the fourth side surface 54 is the end surface of the second die pad 50 in the Y direction that is closer to the fourth sealing side surface 96. The second base surface 52 includes a recess 52A that is recessed from the second sealing side surface 94 toward the first sealing side surface 93 in a plan view.

[0098] The second die pad 50 further has a pair of protrusions 52B and 52C that form the recess 52A. The pair of protrusions 52B and 52C form both ends of the second die pad 50 in the Y direction. The protrusion 52B is the end of both ends of the second die pad 50 in the Y direction that is closer to the third sealing side surface 95, and the protrusion 52C is the end of both ends of the first die pad 30 in the Y direction that is closer to the fourth sealing side surface 96. The third side surface 53 forms a part of the protrusion 52B, and the fourth side surface 54 forms a part of the protrusion 52C. The recess 52A includes a pair of inner side surfaces 52AA and a bottom surface 52AB. As shown in FIG. 10 , each inner side surface 52AA includes a step 52AC.

[0099] As shown in Figures 7 and 10, the second die pad 50 further has a third tip-side inclined portion 55, a fourth tip-side inclined portion 56, a third base-side curved surface 57A, a fourth base-side curved surface 57B, a third recess-side curved surface 58A, and a fourth recess-side curved surface 58B.

[0100] 7 , the second die pad 50 has a shape that is line-symmetrical to the first die pad 30, and therefore the second tip surface 51, the second base end surface 52, the third side surface 53, and the fourth side surface 54 of the second die pad 50 have the same shapes as the first tip surface 31, the first base end surface 32, the first side surface 33, and the second side surface 34 of the first die pad 30. Therefore, the recess 52A has the same shape as the recess 32A. 10 , the third tip-side inclined portion 55 and the fourth tip-side inclined portion 56, and the third base-side curved surface 57A, the fourth base-side curved surface 57B, the third recess-side curved surface 58A, and the fourth recess-side curved surface 58B shown in FIG. 10 have the same shapes as the first tip-side inclined portion 35, the second tip-side inclined portion 36, the first base-side curved surface 37A, the second base-side curved surface 37B, the first recess-side curved surface 38A, and the second recess-side curved surface 38B (see FIGS. 7 and 8 ). The shape of the second die pad 50 may be different from the shape of the first die pad 30.

[0101] The following describes the detailed configuration of each of the second lead terminals 41 to 48. As shown in Fig. 10, the second lead terminals 41 to 48 include second inner lead portions 41A to 48A provided in the sealing resin 90 and the above-mentioned second outer lead portions 41B to 48B. The following describes the configuration of the second inner lead portions 41A to 48A.

[0102] The second inner lead portion 41A is arranged closer to the third sealing side surface 95 than the recessed portion 52A of the second die pad 50. The second inner lead portion 48A is arranged closer to the fourth sealing side surface 96 than the recessed portion 52A of the second die pad 50. The second inner lead portions 42A to 47A are arranged in positions that overlap the recessed portion 52A of the second die pad 50 when viewed from the X direction. The tip portions of the second inner lead portions 42A to 47A are arranged within the recessed portion 52A of the second die pad 50.

[0103] The second inner lead portion 41A is connected to the second base end surface 52 of the second die pad 50. More specifically, the second inner lead portion 41A is connected to the protruding portion 52B of the second die pad 50. The second inner lead portion 41A extends along the X direction. The width dimension (size in the Y direction) of the second inner lead portion 41A is smaller than the width dimension (size in the Y direction) of the protruding portion 52B. The second inner lead portion 41A is positioned closer to the fourth sealing side surface 96 (closer to the second inner lead portion 42A) than the center of the protruding portion 52B in the Y direction.

[0104] The second inner lead portion 48A is connected to the second base end surface 52 of the second die pad 50. More specifically, the second inner lead portion 48A is connected to the protruding portion 52C of the second die pad 50. The second inner lead portion 48A extends along the X direction. The width dimension (size in the Y direction) of the second inner lead portion 48A is smaller than the width dimension (size in the Y direction) of the protruding portion 52C. The second inner lead portion 48A is positioned closer to the fourth sealing side surface 96 (closer to the second inner lead portion 47A) than the center of the protruding portion 52C in the Y direction.

[0105] The second inner lead portion 42A extends along the X direction. The second inner lead portion 42A includes a wire connection portion 42AA and a lead connection portion 42AB that extends from the wire connection portion 42AA toward the second sealing side surface 94. The lead connection portion 42AB is connected to the second outer lead portion 42B.

[0106] The wire connection portion 42AA is disposed in the recess 52A of the second die pad 50. The shape of the wire connection portion 42AA is generally rectangular in plan view. In plan view, the portion of the wire connection portion 42AA closer to the lead connection portion 42AB is formed in a tapered shape such that the width dimension (size in the Y direction) of the wire connection portion 42AA decreases toward the lead connection portion 42AB.

[0107] The lead connection portion 42AB is disposed closer to the second sealing side surface 94 than the recess 52A of the second die pad 50. The lead connection portion 42AB extends in the X direction. In one example, the size of the lead connection portion 42AB in the Y direction is smaller than the size of the wire connection portion 42AA in the Y direction. Therefore, it can be said that the wire connection portion 42AA extends in the Y direction relative to the lead connection portion 42AB.

[0108] The second inner lead portion 43A extends along the X direction and includes a wire connection portion 43AA and a lead connection portion 43AB extending from the wire connection portion 43AA toward the second sealing side surface 94. The lead connection portion 43AB is connected to the second outer lead portion 43B.

[0109] The wire connection portion 43AA is disposed in the recess 52A of the second die pad 50. The wire connection portion 43AA has a generally rectangular shape in plan view. In plan view, a portion of the wire connection portion 43AA closer to the lead connection portion 43AB is tapered such that the width (size in the Y direction) of the wire connection portion 43AA decreases toward the lead connection portion 43AB. A corner portion of the wire connection portion 43AA closer to the bottom surface 52AB of the recess 52A and closer to the wire connection portion 42AA includes an inclined surface 43AC. In plan view, the inclined surface 43AC is inclined away from the wire connection portion 42AA in the Y direction as it approaches the bottom surface 52AB of the recess 52A.

[0110] The lead connection portion 43AB is disposed closer to the second sealing side surface 94 than the recess 52A of the second die pad 50. The lead connection portion 43AB extends in the X direction. In one example, the size of the lead connection portion 43AB in the Y direction is smaller than the size of the wire connection portion 43AA in the Y direction. Therefore, it can be said that the wire connection portion 43AA extends in the Y direction relative to the lead connection portion 43AB.

[0111] The second inner lead portion 44A has the same shape as the second inner lead portion 43A in a plan view. Therefore, only the general configuration of the second inner lead portion 44A will be described, and a detailed description of the second inner lead portion 44A will be omitted.

[0112] The second inner lead portion 44A includes a wire connection portion 44AA and a lead connection portion 44AB. The wire connection portion 44AA is disposed within the recess 52A, and the lead connection portion 44AB is disposed closer to the second sealing side surface 94 than the recess 52A. The lead connection portion 44AB extends in the X direction and is connected to the second outer lead portion 44B. The wire connection portion 44AA extends in the Y direction relative to the lead connection portion 44AB. The wire connection portion 44AA includes an inclined surface 44AC. In one example, the inclined surface 44AC has the same shape as the inclined surface 43AC of the wire connection portion 43AA.

[0113] The second inner lead portions 45A to 47A are symmetrical to the second inner lead portions 42A to 44A with respect to an imaginary line along the X direction at the center of the sealing resin 90 in the Y direction. In other words, the second inner lead portion 45A is symmetrical to the second inner lead portion 44A with respect to the imaginary line. The second inner lead portion 46A is symmetrical to the second inner lead portion 43A with respect to the imaginary line. The second inner lead portion 47A is symmetrical to the second inner lead portion 42A with respect to the imaginary line. For this reason, the configuration of the second inner lead portions 45A to 47A will be described in outline, and a detailed description of the configuration will be omitted.

[0114] The second inner lead portion 45A includes a wire connection portion 45AA and a lead connection portion 45AB. The wire connection portion 45AA is disposed within the recess 52A, and the lead connection portion 45AB is disposed closer to the second sealing side surface 94 than the recess 52A. The lead connection portion 45AB is connected to the second outer lead portion 45B. The wire connection portion 45AA includes an inclined surface 45AC. In a plan view, the inclined surface 45AC is inclined so as to move away from a wire connection portion 46AA (described later) in the Y direction as it approaches the bottom surface 52AB of the recess 52A.

[0115] The second inner lead portion 46A includes a wire connection portion 46AA and a lead connection portion 46AB. The wire connection portion 46AA is disposed within the recess 52A, and the lead connection portion 46AB is disposed closer to the second sealing side surface 94 than the recess 52A. The lead connection portion 46AB is connected to the second outer lead portion 46B. The wire connection portion 46AA includes an inclined surface 46AC. In one example, the inclined surface 46AC has the same shape as the inclined surface 45AC of the wire connection portion 45AA.

[0116] The second inner lead portion 47A includes a wire connection portion 47AA and a lead connection portion 47AB. The wire connection portion 47AA is disposed within the recess 52A, and the lead connection portion 47AB is disposed closer to the second sealing side surface 94 than the recess 52A. The lead connection portion 47AB is connected to the second outer lead portion 47B.

[0117] In this way, the lead connection portions 42AB to 47AB correspond to the "third portion of the second lead terminal," and the wire connection portions 42AA to 47AA correspond to the "fourth portion of the second lead terminal." The X direction in which the lead connection portions 42AB to 47AB extend corresponds to the "first direction," and the Y direction in which the wire connection portions 42AA to 47AA extend corresponds to the "second direction." In the first embodiment, the wire connection portions 42AA to 47AA extend in a direction perpendicular to the direction in which the lead connection portions 42AB to 47AB extend in a plan view, but this is not limited thereto. It is sufficient that the wire connection portions 42AA to 47AA extend in a direction intersecting the direction in which the lead connection portions 42AB to 47AB extend in a plan view.

[0118] Next, the detailed cross-sectional structure of the second inner lead portions 42A to 47A will be described. Figure 11 shows the cross-sectional structure of the wire connection portion 42AA of the second inner lead portion 42A. Note that the cross-sectional structure of the wire connection portions 43AA to 47AA of the second inner lead portions 43A to 47A is similar to the cross-sectional structure of the wire connection portion 42AA, so detailed description thereof will be omitted. For convenience, the reference numerals relating to the second inner lead portion 42A will be the same as those relating to the first inner lead portion 12A.

[0119] 11 , the inner lead body 20B of the wire connection portion 42AA has an inner lead surface 21B, an inner lead back surface 22B opposite to the inner lead surface 21B, and an inner lead side surface 23B connecting the inner lead surface 21B and the inner lead back surface 22B. The inner lead surface 21B of the wire connection portion 42AA faces the same side as the inner lead surface 21B of the wire connection portion 12AA (see FIG. 9 ), and the inner lead back surface 22B of the wire connection portion 42AA faces the same side as the inner lead back surface 22B of the wire connection portion 12AA (see FIG. 9 ).

[0120] In the cross-sectional view of Figure 11, the tip surface 24B is formed as a concave shape recessed away from the second die pad 50 (see Figure 7). The tip surface 24B is recessed from both the end on the inner lead front surface 21B side and the end on the inner lead back surface 22B side toward the center of the tip surface 24B in the Z direction. In one example, the deepest position of the concave tip surface 24B is approximately 1 / 3 of the thickness of the wire connection portion 42AA from the inner lead back surface 22B. Note that the shape of the tip surface 24B in the cross-sectional view of Figure 11 can be changed as desired.

[0121] A plating layer 29 is formed on the inner lead surface 21B. The plating layer 29 is formed of a material containing, for example, silver. In one example, the plating layer 29 is formed of the same material as the plating layer 29 of the wire connection portion 12AA (see FIG. 9 ). The plating layer 29 is formed over substantially the entire inner lead surface 21B. The thickness of the plating layer 29 is thinner than the thickness of the inner lead body 20B of the wire connection portion 42AA. In one example, the thickness of the plating layer 29 of the wire connection portion 42AA is equal to the thickness of the plating layer 29 of the wire connection portion 12AA. Here, if the difference between the thicknesses of the plating layer 29 of the wire connection portion 42AA and the plating layer 29 of the wire connection portion 12AA is, for example, within 20% of the thickness of the plating layer 29 of the wire connection portion 42AA, then the thickness of the plating layer 29 of the wire connection portion 42AA can be said to be equal to the thickness of the plating layer 29 of the wire connection portion 12AA.

[0122] An end surface 29A of the plating layer 29 that is closer to the tip surface 24B of the wire connection portion 42AA is formed at a position closer to the lead connection portion 42AB (see FIG. 10) than the edge of the inner lead surface 21B that is closer to the tip surface 24B. In other words, the plating layer 29 does not cover the edge of the inner lead surface 21B that is closer to the tip surface 24B. As a result, the end of the inner lead surface 21B, including the edge that is closer to the tip surface 24B, is in contact with the sealing resin 90 (see FIG. 1).

[0123] 11 , end surface 29A of plating layer 29 is inclined away from the end surface of inner lead surface 21B closer to tip surface 24B as it moves from the front surface to the back surface of plating layer 29. The distance in the X direction between the back surface of plating layer 29 and the edge of inner lead surface 21B closer to tip surface 24B is, for example, equal to or greater than the thickness of plating layer 29. Note that the distance in the X direction between the back surface of plating layer 29 and the edge of inner lead surface 21B closer to tip surface 24B can be changed as desired.

[0124] Furthermore, the plating layer 29 does not cover the tip surface 24B of the wire connection portion 42AA. Therefore, the tip surface 24B is in contact with the sealing resin 90. Furthermore, although not shown, the plating layer 29 does not cover the inner lead side surface 23B other than the tip surface 24B. Therefore, the inner lead side surface 23B is in contact with the sealing resin 90.

[0125] Next, we will explain the general configuration of the first chip 60 and the second chip 70. As shown in Figure 7, the first chip 60 mounted on the first die pad 30 has a chip front surface 61, a chip back surface 62 (see Figure 19) facing the opposite side to the chip front surface 61 in the Z direction, and first to fourth chip side surfaces 63 to 66 connecting the chip front surface 61 and the chip back surface 62.

[0126] The chip front surface 61 faces the side opposite to the first die pad 30 with respect to the first chip 60, and the chip back surface 62 faces the side facing the first die pad 30. The first chip side surface 63 and the second chip side surface 64 constitute both end faces of the first chip 60 in the X direction in a plan view. The first chip side surface 63 is the chip side surface of the first chip 60 on the side where the first lead terminals 11 to 18 are arranged, and the second chip side surface 64 is the chip side surface of the first chip 60 on the side where the second chip 70 is arranged. The third chip side surface 65 and the fourth chip side surface 66 constitute both end faces of the first chip 60 in the Y direction in a plan view. The third chip side surface 65 is the chip side surface closer to the third sealing side surface 95 of the sealing resin 90, and the fourth chip side surface 66 is the chip side surface closer to the fourth sealing side surface 96.

[0127] The first chip 60 has a plurality of (six in the first embodiment) first electrode pads 67, a plurality of (seven in the first embodiment) second electrode pads 68, and a plurality of (two in the first embodiment) third electrode pads 69. Each of the first electrode pads 67, each of the second electrode pads 68, and each of the third electrode pads 69 is provided so as to be exposed from the chip surface 61.

[0128] Each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 may include at least one of titanium (Ti), titanium nitride (TiN), copper (Cu), aluminum (Al), and tungsten (W). In one example, each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 has a laminated structure of titanium and copper. Note that the material constituting one or two of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 may be different from the material constituting the remaining electrode pads.

[0129] In another example, each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 contains aluminum. In this case, each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 exposed from the chip surface 61 has a thickness of 2 μm or more. Note that the thickness of each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 can be changed as desired.

[0130] The multiple first electrode pads 67 are electrode pads electrically connected to the second chip 70. The multiple first electrode pads 67 are provided at positions closer to the second chip side surface 64 than the center in the X direction of the chip surface 61 in a plan view. The multiple first electrode pads 67 are arranged at the same positions as each other in the X direction and spaced apart from each other in the Y direction.

[0131] The second electrode pads 68 are electrode pads that are individually and electrically connected to the first lead terminals 12 to 17. The second electrode pads 68 are provided at positions closer to the first chip side surface 63 than the center of the chip surface 61 in the X direction in a plan view. The second electrode pads 68 are arranged at the same positions as one another in the X direction and spaced apart from one another in the Y direction, except for one second electrode pad 68 closest to the fourth chip side surface 66. The one second electrode pad 68 closest to the fourth chip side surface 66 is shifted closer to the second chip side surface 64 in the X direction relative to the other second electrode pads 68.

[0132] The multiple third electrode pads 69 are electrode pads electrically connected to the first die pad 30. Each third electrode pad 69 has the same potential as the first die pad 30, i.e., the first ground potential. The multiple third electrode pads 69 are provided at both ends in the Y direction of the chip surface 61 in a plan view. The multiple third electrode pads 69 are arranged between the multiple first electrode pads 67 and the multiple second electrode pads 68 in the X direction when viewed from the Y direction. The multiple third electrode pads 69 are arranged in positions that overlap each other when viewed from the Y direction.

[0133] The second chip 70 mounted on the second die pad 50 has a chip surface 71, a chip back surface (not shown) facing the opposite side of the chip surface 71 in the Z direction, and first to fourth chip side surfaces 73 to 76 connecting the chip surface 71 and the chip back surface.

[0134] The chip front surface 71 faces the side opposite to the second die pad 50 with respect to the second chip 70, and the chip back surface faces the side facing the second die pad 50. The first chip side surface 73 and the second chip side surface 74 constitute both end faces of the second chip 70 in the X direction in a plan view. The first chip side surface 73 is the chip side surface of the second chip 70 on the side where the first chip 60 is arranged, and the second chip side surface 74 is the chip side surface of the second chip 70 on the side where the second lead terminals 41 to 48 are arranged. The third chip side surface 75 and the fourth chip side surface 76 constitute both end faces of the second chip 70 in the Y direction in a plan view. The third chip side surface 75 is the chip side surface closer to the third sealing side surface 95 of the sealing resin 90, and the fourth chip side surface 76 is the chip side surface closer to the fourth sealing side surface 96.

[0135] The second chip 70 has a plurality of (six in the first embodiment) first electrode pads 77, a plurality of (seven in the first embodiment) second electrode pads 78, and a plurality of (three in the first embodiment) third electrode pads 79. Each of the first electrode pads 77, each of the second electrode pads 78, and each of the third electrode pads 79 is provided so as to be exposed from the chip surface 71.

[0136] Each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 may contain at least one of titanium, titanium nitride, copper, aluminum, and tungsten. In one example, each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 has a laminated structure of titanium and copper. Note that the material constituting one or two of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 may be different from the material constituting the remaining electrode pads.

[0137] In another example, each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 contains aluminum. In this case, each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 exposed from the chip surface 71 has a thickness of 2 μm or more. Note that the thickness of each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 can be changed as desired.

[0138] The multiple first electrode pads 77 are electrode pads that are individually and electrically connected to the multiple first electrode pads 67 of the first chip 60. The multiple first electrode pads 77 are provided at positions closer to the first chip side surface 73 than the center in the X direction of the chip surface 71 in a plan view. The multiple first electrode pads 77 are arranged at the same positions as each other in the X direction and spaced apart from each other in the Y direction.

[0139] The second electrode pads 78 are electrode pads that are individually and electrically connected to the second lead terminals 42 to 47. The second electrode pads 78 are provided at positions closer to the second chip side surface 74 than the center of the chip surface 71 in the X direction in a plan view.

[0140] The multiple third electrode pads 79 are electrode pads electrically connected to the second die pad 50. Each third electrode pad 79 has the same potential as the second die pad 50, i.e., the second ground potential. The multiple third electrode pads 79 are provided closer to the third chip side surface 75 than the center in the Y direction of the chip surface 71 in a plan view. The multiple third electrode pads 79 are arranged spaced apart from each other in the X direction.

[0141] Next, the electrical connection configuration between the first chip 60 and the second chip 70 will be described. As shown in Fig. 12, the first electrode pads 67 of the first chip 60 and the first electrode pads 77 of the second chip 70 are individually connected by a plurality of inter-chip wires WA (six in the first embodiment). This electrically connects the first electrode pads 67 and the first electrode pads 77 individually.

[0142] In one example, the distance between two adjacent first electrode pads 67 in the Y direction among the three first electrode pads 67 near the third chip side surface 65 on the first chip 60 is greater than the distance between two adjacent first electrode pads 77 in the Y direction among the three first electrode pads 77 near the third chip side surface 75 on the second chip 70. Therefore, the distance between two adjacent first electrode pads 77 in the Y direction among the three inter-chip wires WA near the third chip side surface 65 (75) gradually increases from the first electrode pad 77 toward the first electrode pad 67.

[0143] Here, the three inter-chip wires WA are designated as inter-chip wires WA1, WA2, and WA3 in order from the third chip side surface 65 (75) to the fourth chip side surface 66 (76). In a plan view, the inter-chip wire WA1 is inclined from the third chip side surface 65 (75) to the fourth chip side surface 66 (76) as it moves from the first electrode pad 67 to the first electrode pad 77. In a plan view, the inter-chip wire WA2 extends along the X direction between the first electrode pad 67 and the first electrode pad 77. In a plan view, the inter-chip wire WA3 is inclined from the fourth chip side surface 66 (76) to the third chip side surface 65 (75) as it moves from the first electrode pad 67 to the first electrode pad 77.

[0144] In a plan view, the acute angle formed between the inter-chip wire WA1 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 7° and less than or equal to 10°.

[0145] In a plan view, the acute angle formed by the inter-chip wires WA1 and WA2 is 10° or less. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 7° and less than or equal to 10°.

[0146] In a plan view, the acute angle formed between the inter-chip wire WA3 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 7° and less than or equal to 10°.

[0147] In a plan view, the acute angle formed between the inter-chip wires WA3 and WA2 is 10° or less. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 7° and less than or equal to 10°.

[0148] In a plan view, the acute angle formed between the inter-chip wires WA1 and WA3 is 10° or less. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 7° and less than or equal to 10°.

[0149] In one example, the distance between two adjacent first electrode pads 67 in the Y direction among the three first electrode pads 67 near the fourth chip side surface 66 on the first chip 60 is greater than the distance between two adjacent first electrode pads 77 in the Y direction among the three first electrode pads 77 near the fourth chip side surface 76 on the second chip 70. Therefore, the distance between two adjacent first electrode pads 77 in the Y direction among the three inter-chip wires WA near the fourth chip side surface 66 (76) gradually increases from the first electrode pad 67 toward the first electrode pad 77.

[0150] Here, the three inter-chip wires WA are designated as inter-chip wires WA4, WA5, and WA6 in order from the third chip side surface 65 (75) to the fourth chip side surface 66 (76). In a plan view, the inter-chip wire WA4 is inclined from the third chip side surface 65 (75) to the fourth chip side surface 66 (76) as it moves from the first electrode pad 67 to the first electrode pad 77. In a plan view, the inter-chip wire WA5 extends along the X direction between the first electrode pad 67 and the first electrode pad 77. In a plan view, the inter-chip wire WA6 is inclined from the fourth chip side surface 66 (76) to the third chip side surface 65 (75) as it moves from the first electrode pad 67 to the first electrode pad 77.

[0151] In a plan view, the acute angle formed between the inter-chip wire WA4 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA4 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA4 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA4 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA4 and the X direction is greater than 7° and less than or equal to 10°.

[0152] In a plan view, the acute angle formed by the inter-chip wires WA4 and WA5 is 10° or less. In one example, the acute angle formed by the inter-chip wires WA4 and WA5 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed by the inter-chip wires WA4 and WA5 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed by the inter-chip wires WA4 and WA5 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed by the inter-chip wires WA4 and WA5 is greater than 7° and less than or equal to 10°.

[0153] In a plan view, the acute angle formed between the inter-chip wire WA6 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA6 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA6 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA6 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA6 and the X direction is greater than 7° and less than or equal to 10°.

[0154] In a plan view, the acute angle formed between the inter-chip wires WA6 and WA5 is 10° or less. In one example, the acute angle formed between the inter-chip wires WA6 and WA5 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wires WA6 and WA5 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wires WA6 and WA5 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wires WA6 and WA5 is greater than 7° and less than or equal to 10°.

[0155] In a plan view, the acute angle formed by the inter-chip wires WA4 and WA6 is 10° or less. In one example, the acute angle formed by the inter-chip wires WA4 and WA6 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed by the inter-chip wires WA4 and WA6 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed by the inter-chip wires WA4 and WA6 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed by the inter-chip wires WA4 and WA6 is greater than 7° and less than or equal to 10°.

[0156] 8, the second electrode pads 68 of the first chip 60 and the first lead terminals 12 to 17 are individually connected by a plurality of first lead wires WB (seven in the first embodiment). This electrically connects the first chip 60 to the first lead terminals 12 to 17. Each of the first lead terminals 13 to 17 is individually connected to the second electrode pads 68 by one first lead wire WB. The first lead terminal 12 is connected to two second electrode pads 68 by two first lead wires WB.

[0157] The first lead wire WB is a bonding wire formed by a wire bonding device. In one example, the first lead wire WB has a first bond portion bonded to the second electrode pad 68 and a second bond portion bonded to the first lead terminals 12 to 17. The first lead wire WB is connected to the wire connection portions 12AA to 17AA of the first inner lead portions 12A to 17A of the first lead terminals 12 to 17.

[0158] 7 , the multiple third electrode pads 69 of the first chip 60 and the first die pad 30 are individually connected by multiple (two in the first embodiment) first die pad wires WC. As a result, the multiple third electrode pads 69 are electrically connected to the first die pad 30. In other words, the multiple third electrode pads 69 are at the first ground potential. It can also be said that the multiple third electrode pads 69 are electrically connected to the first lead terminals 11, 18.

[0159] The first die pad wire WC connected to the third electrode pad 69 of the first chip 60 closer to the third chip side surface 65 is connected to one of the ends of the first die pad 30 in the Y direction that is closer to the first side surface 33. The first die pad wire WC connected to the third electrode pad 69 of the first chip 60 closer to the fourth chip side surface 66 is connected to one of the ends of the first die pad 30 in the Y direction that is closer to the second side surface 34.

[0160] The first die pad wire WC is a bonding wire formed by a wire bonding apparatus. In one example, the first die pad wire WC has a first bond portion bonded to the third electrode pad 69 and a second bond portion bonded to the first die pad 30.

[0161] 10 , the second electrode pads 78 of the second chip 70 and the second lead terminals 42 to 47 are individually connected by a plurality of second lead wires WD (seven in the first embodiment). This electrically connects the second chip 70 to the second lead terminals 42 to 47 individually. Each of the second lead terminals 42 to 45, 47 is individually connected to the second electrode pads 78 by one second lead wire WD. The second lead terminal 46 is connected to two second electrode pads 78 by two second lead wires WD.

[0162] The second lead wire WD is a bonding wire formed by a wire bonding device. In one example, the bonded portion of the second lead wire WD to the second electrode pad 78 is a first bond portion, and the bonded portion of the second lead terminals 42 to 47 is a second bond portion. The second lead wire WD is connected to the wire connection portions 42AA to 47AA of the second inner lead portions 42A to 47A of the second lead terminals 42 to 47.

[0163] 7 , the multiple third electrode pads 79 of the second chip 70 and the second die pad 50 are individually connected by multiple (three in the first embodiment) second die pad wires WE. This electrically connects the second chip 70 and the second die pad 50. Therefore, the third electrode pads 79 of the second chip 70 are at the second ground potential. It can also be said that the third electrode pads 79 are electrically connected to the second lead terminals 41, 48.

[0164] Each of the plurality of second die pad wires WE individually connected to the plurality of third electrode pads 79 is connected to one of the ends of the second die pad 50 in the Y direction that is closer to the third side surface 53. The second die pad wires WE are bonding wires formed by a wire bonding apparatus. In one example, the connection portion of the second die pad wire WE with the third electrode pad 79 is a first bond portion, and the bond portion with the second die pad 50 is a second bond portion.

[0165] 7 and 12, the inter-chip wires WA1 to WA6 are made of a material different from the material making up each of the first lead wires WB, the first die pad wires WC, the second lead wires WD, and the second die pad wires WE. In one example, the first lead wires WB, the first die pad wires WC, the second lead wires WD, and the second die pad wires WE are made of the same material.

[0166] The inter-chip wires WA1 to WA6 are formed of a material containing gold. The first lead wire WB, the first die pad wire WC, the second lead wire WD, and the second die pad wire WE are each formed of a material containing copper. In one example, the first lead wire WB, the first die pad wire WC, the second lead wire WD, and the second die pad wire WE are each configured such that the surface of the copper wire is coated with palladium (Pd). This allows for improved oxidation resistance and corrosion resistance compared to copper wires whose surfaces are not coated with palladium.

[0167] Each of the first lead wire WB, the first die pad wire WC, the second lead wire WD, and the second die pad wire WE may be made of a material containing aluminum.

[0168] In the first embodiment, a security bond WC1 is formed on the second bond portion of each first die pad wire WC, and a security bond WE1 is formed on the second bond portion of each second die pad wire WE.

[0169] 13 shows a perspective view of the second bond portion of the second die pad wire WE and its surroundings. Note that since the configuration of the second bond portion of the second die pad wire WE and the configuration of the second bond portion of the first die pad wire WC are the same, the configuration of the second bond portion of the second die pad wire WE will be described in detail, and a detailed description of the configuration of the second bond portion of the first die pad wire WC will be omitted.

[0170] 13 , the second bond portion of the second die pad wire WE includes a bonding portion WEP bonded to the second die pad 50. The bonding portion WEP is a portion that is crushed by being pressed against the second die pad 50 by the wire bonding device. The thickness of the bonding portion WEP is smaller than the diameter of the second die pad wire WE.

[0171] The security bond WE1 is formed, for example, by providing a stud bump SB on the bonding portion WEP. In one example, the stud bump SB is formed by ball bonding using a wire bonding device. The bonding portion WEP is sandwiched between the second die pad 50 and the stud bump SB.

[0172] [Circuit Configuration of Signal Transmission Device] The circuit configuration of the signal transmission device 10 of the first embodiment will be described with reference to Fig. 14. The signal transmission device 10 includes a first circuit 300, a second circuit 310, and a first transformer 321 and a second transformer 322 configured to insulate the first circuit 300 from the second circuit 310 and to exchange signals between the first circuit 300 and the second circuit 310. In the first embodiment, the first chip 60 includes the first circuit 300, the first transformer 321, and the second transformer 322, and the second chip 70 includes the second circuit 310.

[0173] The signal transmission device 10 also has first terminals P1 to P8 which are external terminals electrically connected to the first circuit 300, and second terminals Q1 to Q8 which are external terminals electrically connected to the second circuit 310.

[0174] The first terminal P1 is a ground terminal (GND1), the first terminal P2 is a positive power supply terminal (VCC1), the first terminal P3 is an adjustment terminal (ADJA), the first terminal P4 is an adjustment terminal (ADJB), the first terminal P5 is a detection terminal (RDYC), the first terminal P6 is a detection terminal (FLT_IN), the first terminal P7 is an input terminal (IN), and the first terminal P8 is a ground terminal (GND2). The first terminal P1 and the first terminal P8 are electrically connected to each other.

[0175] In one example, the first terminal P1 corresponds to the first lead terminal 11, the first terminal P2 corresponds to the first lead terminal 12, the first terminal P3 corresponds to the first lead terminal 13, the first terminal P4 corresponds to the first lead terminal 14, the first terminal P5 corresponds to the first lead terminal 15, the first terminal P6 corresponds to the first lead terminal 16, the first terminal P7 corresponds to the first lead terminal 17, and the first terminal P8 corresponds to the first lead terminal 18.

[0176] The second terminal Q1 is a negative power supply terminal (VEE2), the second terminal Q2 is a clamp terminal (CLAMP), the second terminal Q3 is an off signal output terminal (OFF), the second terminal Q4 is an on signal output terminal (ON), the second terminal Q5 is a voltage detection terminal (DESAT), the second terminal Q6 is a positive power supply terminal (VCC2), the second terminal Q7 is a ground terminal (GND2), and the second terminal Q8 is a negative power supply terminal (VEE2). The second terminals Q1 and Q8 are electrically connected to each other.

[0177] In one example, the second terminal Q1 corresponds to the second lead terminal 41, the second terminal Q2 corresponds to the second lead terminal 42, the second terminal Q3 corresponds to the second lead terminal 43, the second terminal Q4 corresponds to the second lead terminal 44, the second terminal Q5 corresponds to the second lead terminal 45, the second terminal Q6 corresponds to the second lead terminal 46, the second terminal Q7 corresponds to the second lead terminal 47, and the second terminal Q8 corresponds to the second lead terminal 48.

[0178] The first circuit 300 includes a transmitter 301, a transmitter / receiver 302, a PWM (Pulse Width Modulation) generator 303, a logic unit 304, a UVLO (Under Voltage Lock Out) unit 305, a resistor 306, a first switching element 307, and a second switching element 308.

[0179] The first terminal P2 is electrically connected to the UVLO unit 305, the first terminals P3 to P6 are electrically connected to the logic unit 304, and the first terminal P7 is electrically connected to the PWM generation unit 303. The logic unit 304 is individually and electrically connected to the transmission / reception unit 302, the PWM generation unit 303, and the UVLO unit 305. The PWM generation unit 303 is electrically connected to the transmission unit 301.

[0180] The transmitting unit 301 is electrically connected to the first coil of the first transformer 321. The transmitting unit 301 is configured to transmit the PWM signal input from the PWM generating unit 303 to the second circuit 310 using the first transformer 321.

[0181] The PWM generating unit 303 is configured to generate a PWM signal based on an external signal input to a first terminal P7, and output the PWM signal to the transmitting unit 301 and the logic unit 304. A resistor 306 is electrically connected to the conductive path between the first terminal P7 and the PWM generating unit 303. The resistor 306 is, for example, a pull-down resistor. A first terminal of the resistor 306 is electrically connected to the conductive path, and a second terminal of the resistor 306 is electrically connected to the first terminal P1 (P8).

[0182] The transmitter / receiver 302 is electrically connected to the first coil of the second transformer 322. The transmitter / receiver 302 is configured to transmit a signal input from the logic unit 304 to the second circuit 310 using the second transformer 322, and to receive a signal from the second circuit 310 using the second transformer 322.

[0183] The logic unit 304 is configured to exchange various signals with an external control device (not shown) of the signal transmission device 10 via the first terminals P3 to P6, and to exchange various signals with the second circuit 310 using the transmitting unit 301 and the transceiver unit 302.

[0184] A switching element 307 is electrically connected to the conduction path between the first terminal P5 and the logic unit 304. For example, an n-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used as the switching element 307. The drain of the switching element 307 is electrically connected to the conduction path (first terminal P5), and the source of the switching element 307 is electrically connected to the first terminal P1 (P8). The gate of the switching element 307 is electrically connected to the logic unit 304. Therefore, the logic unit 304 controls the switching element 307.

[0185] A switching element 308 is electrically connected to the conduction path between the first terminal P6 and the logic unit 304. For example, an n-channel MOSFET is used as the switching element 308. The drain of the switching element 308 is electrically connected to the conduction path (first terminal P6), and the source of the switching element 308 is electrically connected to the first terminal P1 (P8). The gate of the switching element 308 is electrically connected to the logic unit 304. Therefore, the logic unit 304 controls the switching element 308.

[0186] The logic unit 304 changes the voltages at the first terminals P5 and P6 by turning on and off the switching elements 307 and 308. The control device can grasp the state of the signal transmission device 10 by monitoring the first terminals P5 and P6.

[0187] The UVLO unit 305 stops the operation of the logic unit 304 when the voltage of the control power supply electrically connected to the first terminal P2 falls below a threshold voltage, thereby preventing malfunction. The second circuit 310 includes a receiving unit 311, a transmitting / receiving unit 312, a logic unit 313, a UVLO unit 314, a clamp control unit 315, an output control unit 316, a desaturation fault detection unit 317, a Miller clamp circuit 315A, a first output switching element 316A, a second output switching element 316B, a current source 317A, and a switching element 317B.

[0188] The second terminal Q2 is electrically connected to the clamp control unit 315, the second terminals Q3 and Q4 are electrically connected to the output control unit 316, the second terminals Q5 and Q7 are electrically connected to the desaturation fault detection unit 317, and the second terminal Q6 is electrically connected to the UVLO unit 314. The logic unit 313 is electrically connected to the receiving unit 311, the transceiver unit 312, the UVLO unit 314, the clamp control unit 315, the output control unit 316, and the desaturation fault detection unit 317, individually.

[0189] The receiving unit 311 is electrically connected to the second coil of the first transformer 321. The receiving unit 311 is configured to receive the PWM signal from the transmitting unit 301 via the first transformer 321 and output the received PWM signal to the logic unit 313.

[0190] The transceiver 312 is electrically connected to the second coil of the second transformer 322. The transceiver 312 is configured to transmit a signal input from the logic unit 313 to the transceiver 302 using the second transformer 322, and to receive a signal from the transceiver 302 using the second transformer 322. The transceiver 312 outputs the received signal to the logic unit 313.

[0191] The logic unit 313 is configured to individually control the clamp control unit 315, the output control unit 316, and the desaturation fault detection unit 317. The logic unit 313 is configured to output signals from the clamp control unit 315, the output control unit 316, and the desaturation fault detection unit 317 to the transceiver unit 312.

[0192] The UVLO unit 314 stops operation of the logic unit 313 when the voltage of the control power supply electrically connected to the second terminal Q6 falls below a threshold voltage, thereby preventing malfunction. The clamp control unit 315 is a circuit that controls the operation of the Miller clamp circuit 315A. The Miller clamp circuit 315A includes a first switching element 315B and a second switching element 315C connected in series, and a diode 315D. The first switching element 315B is, for example, a p-channel MOSFET, and the second switching element 315C is, for example, an n-channel MOSFET.

[0193] The source of the first switching element 315B is electrically connected to the second terminal Q6, and the drain of the first switching element 315B is electrically connected to the drain of the second switching element 315C. The source of the second switching element 315C is electrically connected to the second terminal Q1 (Q8). The connection point between the drain of the first switching element 315B and the drain of the second switching element 315C is electrically connected to the second terminal Q2. The anode of the diode 315D is electrically connected to the second terminal Q2 and the drain of the first switching element 315B, and the cathode of the diode 315D is electrically connected to the second terminal Q6 and the source of the first switching element 315B.

[0194] The gate of the first switching element 315B and the gate of the second switching element 315C are each electrically connected to the clamp control unit 315. Therefore, the clamp control unit 315 controls the operation of each of the first switching element 315B and the second switching element 315C.

[0195] The output control unit 316 is a circuit that controls the operation of the first output switching element 316A and the second output switching element 316B. The voltage at the second terminal Q4 changes based on the on / off operation of the first output switching element 316A, and an on signal is output from the second terminal Q4. The voltage at the second terminal Q3 changes based on the on / off operation of the second output switching element 316B, and an off signal is output from the second terminal Q3.

[0196] The first output switching element 316A is, for example, a p-channel MOSFET, and the second output switching element 316B is, for example, an n-channel MOSFET. The gate of the first output switching element 316A and the gate of the second output switching element 316B are each electrically connected to the output control unit 316. The source of the first output switching element 316A is electrically connected to the second terminal Q6, and the drain of the first output switching element 316A is electrically connected to both the second terminal Q4 and the output control unit 316. The drain of the second output switching element 316B is electrically connected to both the second terminal Q3 and the output control unit 316, and the source of the second output switching element 316B is electrically connected to the second terminal Q1 (Q8).

[0197] The fault signal input to the second terminal Q5 is input to the desaturation fault detection unit 317. The desaturation fault detection unit 317 outputs the input fault signal to the logic unit 313. The desaturation fault detection unit 317 is electrically connected to the current source 317A and the switching element 317B.

[0198] The current source 317A is electrically connected to the second terminal Q6 and the second terminal Q5. The current source 317A supplies current to the desaturation fault detection unit 317. An n-channel MOSFET is used as the switching element 317B. The drain of the switching element 317B is electrically connected to the second terminal Q5, and the source of the switching element 317B is electrically connected to the second terminal Q7. The gate of the switching element 317B is electrically connected to the desaturation fault detection unit 317. Therefore, the desaturation fault detection unit 317 controls the operation of the switching element 317B.

[0199] [Detailed Configuration of First Chip] The detailed configuration of the first chip 60 including part of the circuit configuration of the signal transmission device 10 described above will be described with reference to FIGS.

[0200] 15 to 18 show a schematic planar structure of an example of the internal configuration of the first chip 60. Figures 19 to 24 show a schematic cross-sectional structure of an example of the internal configuration of the first chip 60. Note that, to make the drawings easier to understand, some hatching lines have been omitted in the schematic cross-sectional structures of the first chip 60 in Figures 19 to 24.

[0201] (Planar Structure of First Chip) Fig. 15 shows a schematic planar structure of an example of the internal configuration of the first chip 60 near the chip surface 61. Fig. 16 is an enlarged view of an insulating transformer region 110, which will be described later, in Fig. 15. Fig. 17 shows a schematic planar structure of an example of the internal structure of the first chip 60 near the chip back surface 62. Fig. 18 is an enlarged view of the insulating transformer region 110 in Fig. 17.

[0202] The first chip 60 has an isolation transformer region 110, a circuit region 120, and a peripheral guard ring 100 connected to the isolation transformer region 110 and surrounding the circuit region 120. The isolation transformer region 110 electrically insulates the circuit region 120 from the second chip 70 while allowing signal transmission between the circuit region 120 and the second chip 70. The isolation transformer region 110 is formed closer to the second chip side surface 64 than the center of the first chip 60 in the X direction in a plan view. That is, the isolation transformer region 110 is formed in a region of the first chip 60 that is closer to the second chip 70 (see FIG. 7 ) in a plan view. The isolation transformer region 110 extends across substantially the entire first chip 60 in the Y direction.

[0203] 14 are formed in the circuit region 120, except for the first transformer 321 and the second transformer 322. These components include a transmitter 301, a transmitter / receiver 302, a PWM generator 303, a logic unit 304, and a UVLO unit 305. In the following description, the components of the first circuit 300 other than the first transformer 321 and the second transformer 322 may be referred to as "plurality of first functional units" and "plurality of circuit elements."

[0204] A plurality of second electrode pads 68 and a plurality of third electrode pads 69 are formed in the circuit region 120. The plurality of second electrode pads 68 are electrically connected to at least one of the plurality of first function units and the plurality of circuit elements. The plurality of third electrode pads 69 are electrically connected to the plurality of circuit elements.

[0205] A first transformer 321 and a second transformer 322 are formed in the isolation transformer region 110. The first transformer 321 and the second transformer 322 are arranged at the same position in the X direction and spaced apart from each other in the Y direction. In the example shown in Fig. 15 , the first transformer 321 is arranged closer to the third chip side surface 65 in the isolation transformer region 110, and the second transformer 322 is arranged closer to the fourth chip side surface 66 in the isolation transformer region 110.

[0206] 15 and 17, the first transformer 321 includes a first front surface side coil 111A, a first back surface side coil 111B, a second front surface side coil 112A, and a second back surface side coil 112B. The second transformer 322 includes a third front surface side coil 113A, a third back surface side coil 113B, and a fourth front surface side coil 114A, and a fourth back surface side coil 114B.

[0207] 15, the first to fourth surface side coils 111A to 114A are arranged at the same positions in the X direction and spaced apart from one another in the Y direction. The first to fourth surface side coils 111A to 114A are arranged in the order of the first surface side coil 111A, the second surface side coil 112A, the third surface side coil 113A, and the fourth surface side coil 114A, moving from the third chip side surface 65 to the fourth chip side surface 66.

[0208] 17, the first to fourth back-side coils 111B to 114B are arranged at the same positions in the X direction and spaced apart from one another in the Y direction. The first to fourth back-side coils 111B to 114B are arranged in the following order from the third chip side-face 65 to the fourth chip side-face 66: the first back-side coil 111B, the second back-side coil 112B, the third back-side coil 113B, and the fourth back-side coil 114B.

[0209] Although not shown, the first front surface side coil 111A, the second front surface side coil 112A, the third front surface side coil 113A, and the fourth front surface side coil 114A are arranged at the same positions in the Z direction. The first back surface side coil 111B, the second back surface side coil 112B, the third back surface side coil 113B, and the fourth back surface side coil 114B are arranged at the same positions in the Z direction.

[0210] The first to fourth front-surface side coils 111A to 114A and the first to fourth back-surface side coils 111B to 114B may each contain at least one of titanium, titanium nitride, copper, aluminum, and tungsten. For example, the first to fourth front-surface side coils 111A to 114A contain copper, and the first to fourth back-surface side coils 111B to 114B contain aluminum. For example, the first to fourth front-surface side coils 111A to 114A have a laminated structure of titanium and copper, and the first to fourth back-surface side coils 111B to 114B have a laminated structure of titanium nitride and aluminum.

[0211] 15, a plurality of first electrode pads 67 are formed in the insulating transformer region 110. The plurality of first electrode pads 67 are arranged at the same positions in the X direction and spaced apart from one another in the Y direction. The plurality of first electrode pads 67 include six first electrode pads 67A to 67F. The first electrode pads 67A to 67F are arranged in the order of first electrode pads 67A, 67B, 67C, 67D, 67E, and 67F as they move from the third chip side surface 65 to the fourth chip side surface 66.

[0212] 16, the first surface-side coil 111A includes a first coil portion 111A1 that is spiral in plan view, a first outer coil end portion 111A2, and a first inner coil end portion 111A3. The first outer coil end portion 111A2 constitutes the end portion of the outermost periphery of the first coil portion 111A1 in the winding direction, and the first inner coil end portion 111A3 constitutes the end portion of the innermost periphery of the first coil portion 111A1 in the winding direction.

[0213] The second surface-side coil 112A includes a second coil portion 112A1 that is spiral in plan view, a second outer coil end portion 112A2, and a second inner coil end portion 112A3. The second outer coil end portion 112A2 constitutes the end portion of the second coil portion 112A1 in the winding direction at the outermost periphery, and the second inner coil end portion 112A3 constitutes the end portion of the second coil portion 112A1 in the winding direction at the innermost periphery.

[0214] The first electrode pad 67A is disposed in an inner space including the winding center of the first coil portion 111A1 in a plan view. The first electrode pad 67A can be said to be located more inward than the first coil portion 111A1. The first electrode pad 67A is connected to the first inner coil end portion 111A3. Therefore, the first electrode pad 67A can be said to be electrically connected to the first end portion of the first surface side coil 111A.

[0215] The first electrode pad 67B is disposed between the first surface side coil 111A and the second surface side coil 112A in the Y direction in a plan view. The first electrode pad 67B is connected to the first outer coil end 111A2 of the first surface side coil 111A. The first electrode pad 67B is also connected to the second outer coil end 112A2 of the second surface side coil 112A. Therefore, it can be said that the first electrode pad 67B is electrically connected to the second end of the first surface side coil 111A and the second end of the second surface side coil 112A.

[0216] The first electrode pad 67C is disposed in an inner space including the winding center of the second coil portion 112A1 in a plan view. The first electrode pad 67C can be said to be located more inward than the second coil portion 112A1. The first electrode pad 67C is connected to the second inner coil end portion 112A3. Therefore, the first electrode pad 67C can be said to be electrically connected to the first end portion of the second surface side coil 112A.

[0217] The third surface-side coil 113A includes a third coil portion 113A1 that is spiral in plan view, a third outer coil end portion 113A2, and a third inner coil end portion 113A3. The third outer coil end portion 113A2 constitutes the end portion of the third coil portion 113A1 in the winding direction at the outermost periphery, and the third inner coil end portion 113A3 constitutes the end portion of the third coil portion 113A1 in the winding direction at the innermost periphery.

[0218] The fourth surface-side coil 114A includes a fourth coil portion 114A1 that is spiral in plan view, a fourth outer coil end portion 114A2, and a fourth inner coil end portion 114A3. The fourth outer coil end portion 114A2 constitutes the end portion of the fourth coil portion 114A1 in the winding direction at the outermost periphery, and the fourth inner coil end portion 114A3 constitutes the end portion of the fourth coil portion 114A1 in the winding direction at the innermost periphery.

[0219] The first electrode pad 67D is disposed in an inner space including the winding center of the third coil portion 113A1 in a plan view. The first electrode pad 67D can be said to be located more inward than the third coil portion 113A1. The first electrode pad 67D is connected to the third inner coil end portion 113A3. Therefore, the first electrode pad 67D can be said to be electrically connected to the first end portion of the third surface side coil 113A.

[0220] The first electrode pad 67E is disposed between the third surface side coil 113A and the fourth surface side coil 114A in the Y direction in a plan view. The first electrode pad 67E is connected to the third outer coil end 113A2 of the third surface side coil 113A. The first electrode pad 67E is also connected to the fourth outer coil end 114A2 of the fourth surface side coil 114A. Therefore, it can be said that the first electrode pad 67E is electrically connected to the second end of the third surface side coil 113A and the second end of the fourth surface side coil 114A.

[0221] The first electrode pad 67F is disposed in an inner space including the winding center of the fourth coil portion 114A1 in a plan view. The first electrode pad 67F can be said to be located inward of the fourth coil portion 114A1. The first electrode pad 67F is connected to the fourth inner coil end portion 114A3. Therefore, the first electrode pad 67F can be said to be electrically connected to the first end portion of the fourth surface side coil 114A.

[0222] 15 and 16, the first to fourth surface side coils 111A to 114A have the same number of windings. In a plan view, the winding direction of the first surface side coil 111A and the winding direction of the second surface side coil 112A are opposite to each other, and the winding direction of the third surface side coil 113A and the winding direction of the fourth surface side coil 114A are opposite to each other. The winding direction of the first surface side coil 111A and the winding direction of the third surface side coil 113A are the same, and the winding direction of the second surface side coil 112A and the winding direction of the fourth surface side coil 114A are the same.

[0223] As shown in FIG. 18 , the first back-side coil 111B is disposed opposite the first front-side coil 111A (see FIG. 15 ) in the Z direction. The first back-side coil 111B includes a first coil portion 111B1 having a spiral shape in a plan view, a first outer coil end portion 111B2, and a first inner coil end portion 111B3. The first outer coil end portion 111B2 constitutes the end portion of the outermost periphery of the first coil portion 111B1 in the winding direction, and the first inner coil end portion 111B3 constitutes the end portion of the innermost periphery of the first coil portion 111B1 in the winding direction. The first outer coil end portion 111B2 is connected to a first connection wiring 118A extending in the X direction. The first connection wiring 118A is electrically connected to the transmitter 301 (see FIG. 14 ) of the circuit area 120 (see FIG. 17 ). The first inner coil end portion 111B3 is connected to a first wiring (not shown). The first wiring is electrically connected to the transmitting section 301 of the circuit area 120 .

[0224] The second back-side coil 112B is positioned opposite the second front-side coil 112A (see FIG. 15 ) in the Z direction. The second back-side coil 112B includes a second coil portion 112B1 that is spiral-shaped in a plan view, a second outer coil end portion 112B2, and a second inner coil end portion 112B3. The second outer coil end portion 112B2 constitutes the end portion of the outermost periphery of the second coil portion 112B1 in the winding direction, and the second inner coil end portion 112B3 constitutes the end portion of the innermost periphery of the second coil portion 112B1 in the winding direction. The second outer coil end portion 112B2 is connected to a second connection wiring 118B that extends in the X direction. The second connection wiring 118B is positioned adjacent to the first connection wiring 118A in the Y direction. The second connection wiring 118B is positioned closer to the second back-side coil 112B than the first connection wiring 118A. The second connection wiring 118B is electrically connected to the transmitter 301 of the circuit area 120. The second inner coil end 112B3 is connected to a second wiring (not shown). The second wiring is electrically connected to the transmitter 301 of the circuit area 120.

[0225] The third back-surface-side coil 113B is disposed opposite the third front-surface-side coil 113A (see FIG. 15 ) in the Z direction. The third back-surface-side coil 113B includes a third coil portion 113B1 having a spiral shape in a plan view, a third outer coil end portion 113B2, and a third inner coil end portion 113B3. The third outer coil end portion 113B2 constitutes the end portion of the third coil portion 113B1 in the winding direction at the outermost periphery, and the third inner coil end portion 113B3 constitutes the end portion of the third coil portion 113B1 in the winding direction at the innermost periphery. The third outer coil end portion 113B2 is connected to a third connection wiring 118C extending in the X direction. The third connection wiring 118C is electrically connected to the transceiver unit 302 (see FIG. 14 ) of the circuit region 120. The third inner coil end portion 113B3 is connected to a third wiring (not shown). The third wiring is electrically connected to the transmitting / receiving unit 302 in the circuit region 120 .

[0226] The fourth back-side coil 114B is positioned opposite the fourth front-side coil 114A (see FIG. 15 ) in the Z direction. The fourth back-side coil 114B includes a fourth coil portion 114B1 that is spiral-shaped in a plan view, a fourth outer coil end portion 114B2, and a fourth inner coil end portion 114B3. The fourth outer coil end portion 114B2 constitutes the end portion of the fourth coil portion 114B1 in the winding direction at the outermost periphery, and the fourth inner coil end portion 114B3 constitutes the end portion of the fourth coil portion 114B1 in the winding direction at the innermost periphery. The fourth outer coil end portion 114B2 is connected to a fourth connection wiring 118D extending in the X direction. The fourth connection wiring 118D is positioned adjacent to the third connection wiring 118C in the Y direction. The fourth connection wiring 118D is positioned closer to the fourth back-side coil 114B than the third connection wiring 118C. The fourth connection wiring 118D is electrically connected to the transceiver unit 302 of the circuit region 120. The fourth inner coil end portion 114B3 is connected to a fourth wiring (not shown). The fourth wiring is electrically connected to the transceiver unit 302 of the circuit region 120.

[0227] Here, the first to fourth back-side coils 111B to 114B have the same number of windings. In a plan view, the winding direction of the first back-side coil 111B and the winding direction of the second back-side coil 112B are opposite to each other, and the winding direction of the third back-side coil 113B and the winding direction of the fourth back-side coil 114B are opposite to each other. The winding direction of the first back-side coil 111B and the winding direction of the third back-side coil 113B are the same, and the winding direction of the second back-side coil 112B and the winding direction of the fourth back-side coil 114B are the same. In one example, the number of windings of the first to fourth back-side coils 111B to 114B is equal to the number of windings of the first to fourth front-side coils 111A to 114A.

[0228] 16, a front-side guard ring 115 is formed in the insulating transformer region 110. The front-side guard ring 115 surrounds the first to fourth front-side coils 111A to 114A and the first electrode pads 67A to 67F in a plan view. The front-side guard ring 115 has a track shape in a plan view.

[0229] 18, a back-side guard ring 116 is formed in the insulating transformer region 110 to surround the first to fourth back-side coils 111B to 114B in a plan view. The back-side guard ring 116 has a track-like shape in a plan view. The back-side guard ring 116 has the same shape and size as the front-side guard ring 115. In a plan view, the back-side guard ring 116 is formed at a position overlapping the front-side guard ring 115.

[0230] A plurality of vias 117 are formed in the insulating transformer region 110 to connect the front-side guard ring 115 and the back-side guard ring 116. The vias 117 are arranged at positions that overlap both the front-side guard ring 115 and the back-side guard ring 116 in a plan view.

[0231] As shown in FIG. 15 , the circuit region 120 is provided with a plurality of wiring layers 121. The plurality of wiring layers 121 includes a wiring layer that electrically connects the plurality of first functional units and a wiring layer that electrically connects the plurality of functional units to the first transformer 321 and the second transformer 322 in the insulating transformer region 110. The plurality of first functional units are formed in positions in the circuit region 120 closer to the chip back surface 62 (see FIG. 19 ) in the Z direction than the plurality of wiring layers 121. In one example, although not shown in FIG. 17 , the plurality of first functional units are formed in the same positions in the Z direction as the first to fourth back surface side coils 111B to 114B. Note that the positions in the Z direction at which the plurality of first functional units are formed can be changed as desired.

[0232] 15 and 17 , the outer periphery guard ring 100 includes a front-side outer periphery guard ring 101 and a back-side outer periphery guard ring 102. As shown in FIG. 15 , the front-side outer periphery guard ring 101 is connected to the front-side guard ring 115. More specifically, the front-side outer periphery guard ring 101 is connected to both ends of the front-side guard ring 115 in the Y direction. The front-side outer periphery guard ring 101 includes a first portion extending in the X direction at a position adjacent to the third chip side surface 65 in the Y direction in a plan view, a second portion continuing from the first portion and extending in the Y direction at a position adjacent to the second chip side surface 64 in the X direction, and a third portion continuing from the second portion and extending in the X direction at a position adjacent to the fourth chip side surface 66 in the Y direction. The front-side outer periphery guard ring 101 further includes a first connection portion that extends from the first portion toward the front-side guard ring 115 in the Y direction and is connected to the front-side guard ring 115, and a second connection portion that extends from the third portion toward the front-side guard ring 115 in the Y direction and is connected to the front-side guard ring 115. In this way, the front-side outer periphery guard ring 101 is electrically connected to the front-side guard ring 115.

[0233] 17 , the back-side outer periphery guard ring 102 is connected to the back-side guard ring 116. More specifically, the back-side outer periphery guard ring 102 is connected to both ends of the back-side guard ring 116 in the Y direction. The back-side outer periphery guard ring 102 includes a first portion extending in the X direction at a position adjacent to the third chip side surface 65 in the Y direction in a plan view, a second portion continuing from the first portion and extending in the Y direction at a position adjacent to the second chip side surface 64 in the X direction, and a third portion continuing from the second portion and extending in the X direction at a position adjacent to the fourth chip side surface 66 in the Y direction. The back-side outer periphery guard ring 102 further includes a first connection portion extending in the Y direction from the first portion toward the back-side guard ring 116 and connected to the back-side guard ring 116, and a second connection portion extending in the Y direction from the third portion toward the back-side guard ring 116 and connected to the back-side guard ring 116. In this way, the rear surface-side outer peripheral guard ring 102 is electrically connected to the rear surface-side guard ring 116. The shape and size of the rear surface-side outer peripheral guard ring 102 in a plan view are the same as those of the front surface-side outer peripheral guard ring 101. The rear surface-side outer peripheral guard ring 102 is disposed at a position overlapping the front surface-side outer peripheral guard ring 101 in a plan view.

[0234] Although not shown, the first chip 60 has a plurality of peripheral vias that connect the front-side peripheral guard ring 101 and the back-side peripheral guard ring 102. The front-side peripheral guard ring 101 and the back-side peripheral guard ring 102 are electrically connected by the plurality of peripheral vias. Each peripheral via extends in the Z direction.

[0235] (Cross-sectional structure of first chip) A cross-sectional structure of the isolation transformer region 110 will be described as an example of the internal configuration of the first chip 60. Note that, since the first transformer 321 and the second transformer 322 in the isolation transformer region 110 have the same configuration, the following will describe in detail the configuration of the first transformer 321, and will omit a detailed description of the second transformer 322.

[0236] Fig. 19 shows a cross-sectional structure of a portion of the first transformer 321 cut along line F19-F19 in Fig. 15. Fig. 20 is an enlarged view of a portion of the first transformer 321 in Fig. 19. Fig. 21 is an enlarged view of a portion F21 of the first front surface side coil 111A of the first transformer 321 in Fig. 20, and Fig. 22 is an enlarged view of a portion F22 of the first back surface side coil 111B of the first transformer 321 in Fig. 20. Note that hatching lines have been omitted in Fig. 19 to facilitate understanding of the drawing.

[0237] 19 , the first chip 60 includes the substrate 130 described above and an element insulating layer 150 formed on the substrate 130. The substrate 130 is formed, for example, of a semiconductor substrate. In the first embodiment, the substrate 130 is a semiconductor substrate formed of a material containing silicon (Si). Note that a wide bandgap semiconductor or a compound semiconductor may be used as the semiconductor substrate for the substrate 130. Alternatively, instead of a semiconductor substrate, the substrate 130 may be an insulating substrate formed of a material containing glass or a material containing ceramics such as alumina.

[0238] The wide bandgap semiconductor is a semiconductor substrate having a bandgap of 2.0 eV or greater. The wide bandgap semiconductor may be silicon carbide (SiC). The compound semiconductor may be a III-V compound semiconductor. The compound semiconductor may include at least one of aluminum nitride (AlN), indium nitride (InN), gallium nitride (GaN), and gallium arsenide (GaAs).

[0239] The substrate 130 is formed in a flat plate shape and has a substrate front surface 131 and a substrate back surface 132 opposite to the substrate front surface 131. The substrate back surface 132 constitutes the chip back surface 62 of the first chip 60.

[0240] The element insulating layer 150 is in contact with the substrate surface 131. In one example, the element insulating layer 150 is formed over the entire surface of the substrate surface 131. In one example, the element insulating layer 150 is made of silicon oxide (SiO ２) The element insulating layer 150 may be formed by stacking a plurality of such oxide films. The material forming the element insulating layer 150 can be changed as desired.

[0241] The element insulating layer 150 has a layer front surface 151 and a layer back surface 152 opposite to the layer front surface 151. The layer front surface 151 faces the same side as the substrate front surface 131, and the layer back surface 152 faces the same side as the substrate back surface 132. The layer back surface 152 is in contact with the substrate front surface 131.

[0242] On the element insulating layer 150, a plurality of first electrode pads 67A to 67F (not shown in FIG. 19, see FIG. 16), a passivation film 161, and a protective film 162 (see FIG. 20 for both) are formed.

[0243] The plurality of first electrode pads 67A to 67F are in contact with the layer surface 151 of the element insulating layer 150. In one example, the plurality of first electrode pads 67A to 67F are formed at the same positions as one another in the Z direction.

[0244] As shown in FIG. 20 , the passivation film 161 is a film that protects the element insulating layer 150 and is formed to cover the layer surface 151. The passivation film 161 is formed to cover the multiple first electrode pads 67A to 67F. Meanwhile, the passivation film 161 has openings (not shown) that expose portions of the multiple first electrode pads 67A to 67F in the Z direction. The protective film 162 is formed on the passivation film 161. In one example, the passivation film 161 is formed of a single layer of a silicon nitride (SiN) film or a silicon oxynitride (SiON) film. In another example, the passivation film 161 is formed of a stacked structure of a silicon oxide film and a silicon nitride film. In this case, the silicon nitride film may be formed on a silicon oxide film. In another example, the passivation film 161 is formed of a stacked structure of a silicon oxide film and a silicon oxynitride film. In this case, the silicon oxynitride film may be formed on a silicon oxide film.

[0245] The thickness of the passivation film 161 (the size of the passivation film 161 in the Z direction) is thinner than the thickness of the protective film 162 (the size of the protective film 162 in the Z direction). In one example, the thickness of the passivation film 161 is ⅓ or less of the thickness of the protective film 162. In another example, the thickness of the passivation film 161 is ¼ or less of the thickness of the protective film 162. In another example, the thickness of the passivation film 161 is ⅕ or more of the thickness of the protective film 162. In the example shown in FIG. 20 , the thickness of the passivation film 161 is about 1.3 μm.

[0246] The protective film 162 is formed on the passivation film 161. The protective film 162 is a film that protects the first chip 60, and is formed of a material containing, for example, polyimide (PI). The protective film 162 can also be said to be a layer that relieves stress between the sealing resin 90 and the element insulating layer 150 and between the sealing resin 90 and the substrate 130. The protective film 162 forms the chip surface 61 of the first chip 60.

[0247] The first surface side coil 111A and the first back side coil 111B of the first transformer 321 are arranged opposite to each other with a gap in the Z direction. An element insulating layer 150 is interposed between the first surface side coil 111A and the first back side coil 111B in the Z direction. The first surface side coil 111A and the first back side coil 111B are provided in the element insulating layer 150. The first back side coil 111B can also be said to be embedded in the element insulating layer 150. The first surface side coil 111A is arranged closer to the layer surface 151 of the element insulating layer 150 than the first back side coil 111B. In other words, the first back side coil 111B is arranged closer to the layer back surface 152 of the element insulating layer 150 (closer to the substrate 130) than the first surface side coil 111A. The first surface side coil 111A is exposed from the layer surface 151 of the element insulating layer 150 in the Z direction. The first front surface side coil 111A is covered with a passivation film 161. The first back surface side coil 111B is disposed at a distance in the Z direction from the layer back surface 152 of the element insulating layer 150. In other words, the first back surface side coil 111B is disposed at a distance in the Z direction from the substrate 130. The element insulating layer 150 is interposed between the first back surface side coil 111B and the substrate 130.

[0248] As shown in Fig. 21 , the first surface side coil 111A is embedded in a recess 153 recessed from the layer front surface 151 toward the layer back surface 152 (see Fig. 20 ) of the element insulating layer 150. The recess 153 is formed in a spiral shape in a plan view. The first surface side coil 111A is formed by a single conductor 170 embedded in the recess 153. In other words, the first surface side coil 111A is configured by a single conductor 170 formed in a spiral shape in a plan view.

[0249] The conducting wire 170 has a coil front surface 171, a coil back surface 172 opposite the coil front surface 171, and a pair of coil side surfaces 173 connecting the coil front surface 171 and the coil back surface 172. The coil front surface 171 faces the same side as the layer front surface 151 of the element insulating layer 150, and the coil back surface 172 faces the same side as the layer back surface 152. The pair of coil side surfaces 173 are formed in a tapered shape whose size in the X direction decreases from the coil front surface 171 toward the coil back surface 172. The coil back surface 172 and the pair of coil side surfaces 173 are in contact with the recess 153. In other words, the coil back surface 172 and the pair of coil side surfaces 173 are in contact with the element insulating layer 150. The coil front surface 171 is covered with a passivation film 161.

[0250] The conductive wire 170 includes a barrier layer 174 and a metal layer 175 formed on the barrier layer 174. The barrier layer 174 is formed so as to contact the recess 153. The barrier layer 174 can be said to be a thin film interposed between the metal layer 175 and the element insulating layer 150. The metal layer 175 is formed so as to fill the recess 153.

[0251] The metal layer 175 is formed of a material containing, for example, copper. The barrier layer 174 has a function of suppressing the diffusion of copper, for example. The barrier layer 174 may contain at least one of titanium, titanium nitride, tantalum (Ta), and tantalum nitride (TaN). The metal layer 175 may also contain at least one of aluminum, gold (Au), silver, and tungsten (W).

[0252] The thickness of the conductor 170 of the first front-side coil 111A is thicker than the thickness of the passivation film 161 and thinner than the thickness of the protective film 162. The thickness of the conductor 170 is thicker than the thickness of the first back-side coil 111B (see FIG. 20 ). In one example, the thickness of the conductor 170 is between two and three times the thickness of the passivation film 161. In one example, the thickness of the conductor 170 is half or less the thickness of the protective film 162. In one example, the thickness of the conductor 170 is one-third or more the thickness of the protective film 162. Here, the thickness of the conductor 170 can be defined by the distance between the coil front surface 171 and the coil back surface 172 in the Z direction.

[0253] The width of coil surface 171 of conducting wire 170 (the length in the X direction in FIG. 21 ) is longer than the thickness of conducting wire 170. In one example, the width of coil surface 171 is more than twice the thickness of conducting wire 170. In another example, the width of coil surface 171 is less than three times the thickness of conducting wire 170. In the example of FIG. 21 , the width of coil surface 171 is approximately 6.8 μm.

[0254] In the first surface side coil 111A, an element insulating layer 150 is interposed between adjacent conductors 170 in the X direction. That is, in the first surface side coil 111A, the conductors 170 are spaced apart from each other in the X direction. The distance between adjacent conductors 170 in the X direction gradually increases from the coil front surface 171 toward the coil back surface 172.

[0255] In FIG. 21 , the distance between adjacent conductors 170 in the X direction, and the distance between the coil surfaces 171 of adjacent conductors 170 in the X direction, is defined as the inter-conductor distance. This inter-conductor distance refers to the minimum distance between adjacent conductors 170 in the X direction. The inter-conductor distance is smaller than the length of the coil surface 171 in the X direction. In one example, the inter-conductor distance is ½ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ⅓ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ¼ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ⅕ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ⅙ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ⅙ or less of the width of the coil surface 171. In one example, the inter-conductor distance is ⅙ or more of the width of the coil surface 171. The inter-conductor distance is smaller than the thickness of the conductors 170. In one example, the distance between the conductors is equal to or less than ½ of the thickness of the conductors 170. In another example, the distance between the conductors is equal to or more than ⅓ of the thickness of the conductors 170. In the example of Fig. 21, the distance between the conductors is about 1 µm.

[0256] 20 and 22, the first back-side coil 111B is composed of two coil layers 111BA and 111BB. The coil layer 111BA constitutes a conductor closer to the layer front surface 151 of the element insulating layer 150, and the coil layer 111BB constitutes a conductor closer to the layer back surface 152. The coil layers 111BA and 111BB are spaced apart in the Z direction. The element insulating layer 150 is interposed between the coil layers 111BA and 111BB in the Z direction. Each of the coil layers 111BA and 111BB includes a conductor 180. That is, the coil layer 111BA is constituted by a conductor 180 formed in a spiral shape in a plan view, and the coil layer 111BB is constituted by another conductor 180 formed in a spiral shape in a plan view. Here, the number of turns of the first back-side coil 111B can be defined as the sum of the number of turns of the coil layer 111BA and the number of turns of the coil layer 111BB.

[0257] As shown in Fig. 20, the coil layer 111BA and the coil layer 111BB are arranged to be offset from each other in the X direction. In plan view, the coil layer 111BA and the coil layer 111BB are arranged to partially overlap each other. In other words, in plan view, the coil layer 111BA and the coil layer 111BB are arranged to have portions that do not overlap each other. In the example shown in Fig. 22, the coil layer 111BA is arranged to be offset in the X direction from the coil layer 111BB by half the width dimension of the conductor 180 (the length in the X direction in Fig. 22).

[0258] Each of the coil layers 111BA and 111BB is disposed offset in the X direction with respect to the first surface side coil 111A. In a plan view, the coil layers 111BA and 111BB are disposed so as to partially overlap the first surface side coil 111A. In the example shown in FIG. 22 , the coil layer 111BA is offset toward the first chip side surface 63 (see FIG. 15 ) with respect to the first surface side coil 111A (see FIG. 20 ). The coil layer 111BB is offset toward the second chip side surface 64 (see FIG. 15 ) with respect to the first surface side coil 111A.

[0259] The number of turns of the coil layer 111BA and the number of turns of the coil layer 111BB are the same. The number of turns of the coil layers 111BA and 111BB is less than the number of turns of the first front-side coil 111A. In one example, the number of turns of the coil layer 111BA is half the number of turns of the first front-side coil 111A, and the number of turns of the coil layer 111BB is half the number of turns of the first front-side coil 111A. In other words, the sum of the number of turns of the coil layer 111BA and the number of turns of the coil layer 111BB is the same as the number of turns of the first front-side coil 111A. Therefore, the number of turns of the first back-side coil 111B is the same as the number of turns of the first front-side coil 111A.

[0260] The coil layers 111BA and 111BB are formed by identically shaped conductors 180 that are spirally wound in a plan view. The conductor 180 has a coil front surface 181, a coil back surface 182 opposite the coil front surface 181, and a pair of coil side surfaces 183 connecting the coil front surface 181 and the coil back surface 182. The coil front surface 181 faces the same side as the layer front surface 151 of the element insulating layer 150, and the coil back surface 172 faces the same side as the layer back surface 152. The pair of coil side surfaces 183 extend along the Z direction. The coil front surface 181, the coil back surface 182, and the pair of coil side surfaces 183 each contact the element insulating layer 150.

[0261] The conductor 180 includes a back-side barrier layer 184, a metal layer 185 formed on the back-side barrier layer 184, and a front-side barrier layer 186 formed on the metal layer 185. The back-side barrier layer 184 constitutes a coil back surface 182 of the conductor 180. The back-side barrier layer 184 can be said to be a thin film interposed between the back surface of the metal layer 185 and the element insulating layer 150 in the Z direction.

[0262] The front-side barrier layer 186 constitutes the coil surface 181 of the conductor 180. The front-side barrier layer 186 can be said to be a thin film interposed between the surface of the metal layer 185 and the element insulating layer 150 in the Z direction.

[0263] The metal layer 185 has a thickness greater than that of the back-side barrier layer 184 and the front-side barrier layer 186. A pair of side surfaces of the metal layer 185 are not covered by either the back-side barrier layer 184 or the front-side barrier layer 186 and are in contact with the element insulating layer 150. The pair of side surfaces of the metal layer 185 constitute part of the pair of coil side surfaces 183 in the Z direction.

[0264] The metal layer 185 is formed of a material containing, for example, aluminum. Both the back-side barrier layer 184 and the front-side barrier layer 186 may contain titanium or titanium nitride. In this way, the material constituting the first back-side coil 111B is different from the material constituting the first front-side coil 111A.

[0265] The materials constituting the first front-side coil 111A and the first back-side coil 111B can be changed as desired. For example, the materials constituting the first front-side coil 111A and the first back-side coil 111B may be the same.

[0266] As shown in FIG. 20 , the thickness of the conductor 180 of the first back-side coil 111B is thinner than the thickness of the protective film 162. The thickness of the conductor 180 is thinner than the thickness of the conductor 170. In one example, the thickness of the conductor 180 is half or less of the thickness of the conductor 170. In one example, the thickness of the conductor 180 is about one-third of the thickness of the conductor 170. The thickness of the conductor 180 is thinner than the thickness of the passivation film 161. The thickness of the conductor 180 is half or more of the thickness of the passivation film 161. Here, the thickness of the conductor 180 can be defined by the distance in the Z direction between the coil front surface 181 and the coil back surface 182.

[0267] The width of the conductor 180 (the length in the X direction in FIG. 20 ) is longer than the thickness of the conductor 180. In one example, the width of the conductor 180 is at least twice the thickness of the conductor 180. In one example, the width of the conductor 180 is at least five times the thickness of the conductor 180. In one example, the width of the conductor 180 is at least ten times the thickness of the conductor 180. In one example, the width of the conductor 180 is at least twelve times the thickness of the conductor 180. In one example, the width of the conductor 180 is at least fifteen times the thickness of the conductor 180. In one example, the width of the conductor 180 is at least sixteen times the thickness of the conductor 180. In one example, the width of the conductor 180 is approximately seventeen times the thickness of the conductor 180.

[0268] In one example, the width dimension of the conductor 180 is longer than the width dimension of the conductor 170. The width dimension of the conductor 180 is at least twice the width dimension of the conductor 170. The width dimension of the conductor 180 is no more than three times the width dimension of the conductor 170. In the example of FIG. 20 , the width dimension of the conductor 180 is approximately 15.8 μm. The width dimension of the conductor 170 can be defined as the size in a direction perpendicular to the direction in which the conductor 170 extends in a planar view. The width dimension of the conductor 180 can be defined as the size in a direction perpendicular to the direction in which the conductor 180 extends in a planar view.

[0269] In the coil layers 111BA and 111BB, an element insulating layer 150 is interposed between adjacent conductors 180 in the X direction. That is, in the coil layers 111BA and 111BB, the conductors 180 are spaced apart in the X direction. The distance between adjacent conductors 180 in the X direction (hereinafter referred to as the "inter-conductor distance") is the same from the coil front surface 181 to the coil back surface 182. The inter-conductor distance is smaller than the width of the conductors 180. For example, the inter-conductor distance is ½ or less of the width of the conductors 180. For example, the inter-conductor distance is ⅕ or less of the width of the conductors 180. For example, the inter-conductor distance is 1 / 10 or less of the width of the conductors 180. For example, the inter-conductor distance is 1 / 15 or less of the width of the conductors 180. For example, the inter-conductor distance is 1 / 16 or less of the width of the conductors 180. In one example, the inter-wire distance is 1 / 17 or less of the width dimension of the conductor 180. In one example, the inter-wire distance is 1 / 18 or less of the width dimension of the conductor 180. In one example, the inter-wire distance is 1 / 19 or less of the width dimension of the conductor 180. In one example, the inter-wire distance is 1 / 20 or more of the width dimension of the conductor 180. The inter-wire distance is smaller than the thickness of the conductor 180. On the other hand, the inter-wire distance is 1 / 2 or more of the thickness of the conductor 180. The inter-wire distance of the coil layers 111BA, 111BB is smaller than the inter-wire distance of the first surface-side coil 111A. In the example of FIG. 20 , the inter-wire distance is approximately 0.8 μm.

[0270] The distance in the Z direction between the first front surface side coil 111A and the first back surface side coil 111B is greater than the distance in the Z direction between the layer back surface 152 of the element insulating layer 150 and the first back surface side coil 111B. In one example, the distance in the Z direction between the first front surface side coil 111A and the first back surface side coil 111B is smaller than the width dimension of the conductive wire 180. The distance in the Z direction between the first front surface side coil 111A and the first back surface side coil 111B is, for example, approximately 12.8 μm. Here, the distance in the Z direction between the first front surface side coil 111A and the first back surface side coil 111B can be defined by the distance in the Z direction between the coil back surface 172 of the conductive wire 170 and the coil front surface 181 of the conductive wire 180 of the coil layer 111BA. The distance in the Z direction between the first front side coil 111A and the first back side coil 111B is set according to the desired dielectric strength and the electric field strength of each of the first front side coil 111A and the first back side coil 111B.

[0271] In the first embodiment, the conductor 170 of the first surface side coil 111A is formed so that the coil front surface 171 thereof is exposed from the element insulating layer 150 in the Z direction, but this is not limited to this. The conductor 170 of the first surface side coil 111A may be embedded in the element insulating layer 150. In other words, the coil front surface 171 of the conductor 170 may be in contact with the element insulating layer 150. In other words, the conductor 170 may be disposed closer to the layer rear surface 152 than the layer front surface 151 of the element insulating layer 150.

[0272] 23 and 24, an example of the wiring structure of the circuit region 120 will be described. The circuit region 120 includes a wiring layer 121 shown in FIG. 15 and a substrate-side wiring layer 122 disposed closer to the substrate 130 than the wiring layer 121.

[0273] In one example, the wiring layer 121 is formed at the same position in the Z direction as the first surface side coil 111A of the first transformer 321. That is, the surface of the wiring layer 121 is exposed from the layer surface 151 of the element insulating layer 150 and is covered with the passivation film 161. In the example shown in Fig. 23, the thickness of the wiring layer 121 is 2.8 µm.

[0274] The substrate-side wiring layer 122 is embedded in the element insulating layer 150. In one example, the substrate-side wiring layer 122 includes a first wiring layer 122A, a second wiring layer 122B, and a third wiring layer 122C. The first wiring layer 122A is arranged closer to the substrate 130 in the Z direction than the second wiring layer 122B and the third wiring layer 122C. The first wiring layer 122A is arranged spaced apart in the Z direction from the layer rear surface 152 of the element insulating layer 150. In other words, the first wiring layer 122A is arranged spaced apart from the substrate 130 in the Z direction. The element insulating layer 150 is interposed between the first wiring layer 122A and the substrate 130 in the Z direction.

[0275] The circuit region 120 includes a first via 123 that connects the wiring layer 121 and the substrate-side wiring layer 122. In the example shown in Fig. 23, the first via 123 connects the wiring layer 121 and the first wiring layer 122A. The first via 123 is formed of, for example, the same material as the wiring layer 121.

[0276] 24, first via 123 includes barrier layer 123A and metal layer 123B, similar to, for example, conductive wire 170. The materials constituting barrier layer 123A and metal layer 123B are the same as, for example, barrier layer 174 and metal layer 175 of conductive wire 170 (both see FIG. 21).

[0277] 23, the circuit region 120 includes a second via 124 connecting the first wiring layer 122A and the substrate 130, a third via 125 connecting the first wiring layer 122A and the second wiring layer 122B, and a fourth via 126 connecting the second wiring layer 122B and the third wiring layer 122C. As a result, in the example shown in Fig. 23, the substrate-side wiring layer 122 is electrically connected to the substrate 130. The first to fourth vias 123 to 126 are formed of a material containing, for example, tungsten.

[0278] As shown in FIG. 24 , the first wiring layer 122A, the second wiring layer 122B, and the third wiring layer 122C have different thicknesses. The thickness of the first wiring layer 122A is thinner than both the thickness of the second wiring layer 122B and the thickness of the third wiring layer 122C. The thickness of the second wiring layer 122B is the same as the thickness of the third wiring layer 122C. In other words, the thicknesses of the first to third wiring layers 122A to 122C are thinner in the Z direction near the substrate 130. In other words, the thicknesses of the first to third wiring layers 122A to 122C are thicker as they move away from the substrate 130 in the Z direction. In one example, the thicknesses of the second wiring layer 122B and the third wiring layer 122C are less than twice the thickness of the first wiring layer 122A. 24, the thickness of the first wiring layer 122A is, for example, 0.52 μm, and the thicknesses of the second wiring layer 122B and the third wiring layer 122C are, for example, 0.93 μm. In addition, in one example, the second wiring layer 122B is formed at the same position in the Z direction as the coil layer 111BB of the first back-side coil 111B, and the third wiring layer 122C is formed at the same position in the Z direction as the coil layer 111BA.

[0279] Effects of the First Embodiment The signal transmission device 10 of the first embodiment provides the following effects. (1-1) The signal transmission device 10 includes inter-chip wires WA that electrically connect the first chip 60 and the second chip 70, and first lead wires WB that individually connect the first chip 60 and the first lead terminals 11. The inter-chip wires WA are made of a material containing gold. The first lead wires WB are made of a material containing copper or aluminum.

[0280] The inter-chip wires WA are relatively important from the viewpoint of the insulation reliability of the signal transmission device 10, and the height and shape of the wires must be inspected with high precision. In this regard, in the first embodiment, the inter-chip wires WA are formed from a material containing gold, and therefore, when the height of the inter-chip wires WA is inspected using, for example, X-ray inspection, the inter-chip wires WA are displayed more clearly than when the inter-chip wires WA are formed from a material containing copper or aluminum. Therefore, the height of the inter-chip wires WA can be inspected accurately. Furthermore, the shape of the inter-chip wires WA can also be inspected accurately.

[0281] On the other hand, the first lead wires WB are less important than the inter-chip wires WA in terms of the insulation reliability of the signal transmission device 10. In this regard, in the first embodiment, the first lead wires WB are formed from a material containing copper or aluminum, which allows for cost reduction compared to when the first lead wires WB are formed from a material containing gold. In this way, it is possible to achieve both improved quality and cost reduction for the signal transmission device 10.

[0282] (1-2) The first lead wire WB is configured such that the surface of the copper wire is coated with palladium. With this configuration, the palladium coated on the surface of the copper wire can increase the bonding area of ​​the bonding portion between the first lead wire WB, which serves as the second bond portion of the first lead wire WB, and the first lead terminals 11 to 18. This increases the bonding strength between the first lead wire WB and the first lead terminals 11 to 18, thereby suppressing the occurrence of cracks at the bonding portions between the first lead wire WB and the first lead terminals 11 to 18.

[0283] (1-3) The signal transmission device 10 further includes a plurality of second lead wires WD that individually connect the second chip 70 to the second lead terminals 41 to 48. The second lead wires WD are formed of a material containing copper or aluminum.

[0284] According to this configuration, the second lead wire WD, which is less important than the inter-chip wire WA from the standpoint of insulation reliability of the signal transmission device 10, is formed from a material containing copper or aluminum, thereby enabling cost reduction compared to when the second lead wire WD is formed from a material containing gold.

[0285] (1-4) The second lead wire WD is a copper wire whose surface is coated with palladium. This configuration provides the same effect as that of (1-2) above.

[0286] (1-5) The signal transmission device 10 further includes a first die pad wire WC that connects the first chip 60 and the first die pad 30. The first die pad wire WC is made of a material containing copper or aluminum. This configuration provides the same effect as the effect described in (1-3) above.

[0287] (1-6) The first die pad wire WC is a copper wire whose surface is coated with palladium. This configuration provides the same effect as that of (1-2) above.

[0288] (1-7) A security bond WC1 is formed at the bonding portion between the first die pad wire WC, which is the second bond portion of the first die pad wire WC, and the first die pad 30.

[0289] According to this configuration, the security bond WC1 can thicken the second bond portion of the first die pad wire WC, thereby suppressing the occurrence of cracks in the second bond portion of the first die pad wire WC.

[0290] (1-8) The signal transmission device 10 further includes a second die pad wire WE that connects the second chip 70 and the second die pad 50. The second die pad wire WE is made of a material containing copper or aluminum. This configuration provides the same effect as the effect described in (1-3) above.

[0291] (1-9) The second die pad wire WE is a copper wire whose surface is coated with palladium. This configuration provides the same effect as that of (1-2) above.

[0292] (1-10) A security bond WE1 is formed at the joint between the second die pad wire WE, which is the second bond portion of the second die pad wire WE, and the second die pad 50. This configuration provides the same effect as in (1-7) above.

[0293] (1-11) Each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 of the first chip 60 has a thickness of 2 μm or more. With this configuration, even if an inter-chip wire WA is bonded to each of the first electrode pads 67, it is possible to prevent cracks from occurring in the element insulating layer 150 directly below each of the first electrode pads 67. Even if a first lead wire WB is bonded to each of the second electrode pads 68, it is possible to similarly prevent cracks from occurring in the element insulating layer 150. Even if a first die pad wire WC is bonded to each of the third electrode pads 69, it is possible to similarly prevent cracks from occurring in the element insulating layer 150.

[0294] (1-12) The sealing resin 90 contains sulfur as an additive. The concentration of sulfur added is 300 μg / g or less. This configuration can reduce sulfide corrosion of copper wires whose surfaces are coated with palladium, such as the first lead wire WB, the second lead wire WD, the first die pad wire WC, and the second die pad wire WE.

[0295] (1-13) A plating layer 29 is formed on the inner lead surface 21B of the wire connection portion 12AA of the first inner lead portion 12A of the first lead terminal 12. The plating layer 29 is not formed on the end of the inner lead surface 21B of the wire connection portion 12AA on the tip surface 24B side, and the end is in contact with the sealing resin 90.

[0296] This configuration can prevent peeling of the plating layer 29 at the end of the inner lead surface 21B of the wire connection portion 12AA near the tip surface 24B from the sealing resin 90. Note that the wire connection portions 13AA to 17AA of the first lead terminals 13 to 17 have a similar configuration, and therefore the same effect can be obtained.

[0297] (1-14) A plating layer 29 is formed on the inner lead surface 21B of the wire connection portion 42AA of the second inner lead portion 42A of the second lead terminal 42. The plating layer 29 is not formed on the end of the inner lead surface 21B of the wire connection portion 42AA on the tip surface 24B side, and the end is in contact with the sealing resin 90.

[0298] This configuration can prevent peeling of the plating layer 29 at the end of the wire connection portion 42AA on the inner lead surface 21B near the tip surface 24B from occurring between the sealing resin 90. Note that the wire connection portions 43AA to 47AA of the second lead terminals 43 to 47 have a similar configuration, and therefore the same effect can be obtained.

[0299] (1-15) A plating layer 26 is formed on the outer lead surface 21A, outer lead back surface 22A, and outer lead side surface 23A of the outer lead body 20A of the first outer lead portions 11B to 18B. The plating layer 26 is formed continuously from the outer lead back surface 22A to the outer lead surface 21A on the outer lead end surface 24A. The plating layer 26 is spaced apart from the outer lead surface 21A.

[0300] With this configuration, when the signal transmission device 10 is mounted on the circuit board PCB using the conductive bonding material SD, the conductive bonding material SD comes into contact with the plating layer 26 formed on the outer lead end surface 24A. This causes the conductive bonding material SD in contact with the outer lead end surface 24A to form a fillet. This makes it easy to check the state in which the signal transmission device 10 is mounted on the circuit board PCB.

[0301] (1-16) The outer surface of the sealing resin 90 is formed so that the surface roughness Rz is 8 μm or more. This configuration increases the creepage distance between the first lead terminals 11 to 18 and the second lead terminals 41 to 48 via the sealing resin 90. This improves the dielectric strength between the first lead terminals 11 to 18 and the second lead terminals 41 to 48.

[0302] 25 and 26, a signal transmission device 10 according to a second embodiment will be described. The signal transmission device 10 according to the second embodiment differs from the signal transmission device 10 according to the first embodiment in the configuration of the first frame 10A and the second frame 10B. In the following description, the configuration that differs from the first embodiment will be described in detail, and components that are common to the first embodiment will be denoted by the same reference numerals and will not be described again.

[0303] As shown in FIG. 25 , the shapes of the wire connection portions 12AA and 17AA of the first lead terminals 12 and 17 of the first frame 10A are different from those in the first embodiment. More specifically, the corner portion of the tip end of the wire connection portion 12AA that is closer to the first lead terminal 13 includes an inclined surface 12AC. The inclined surface 12AC is inclined away from the first lead terminal 13 side surface of both sides of the wire connection portion 12AA toward the tip end surface of the wire connection portion 12AA. The corner portion of the tip end of the wire connection portion 17AA that is closer to the first lead terminal 16 includes an inclined surface 17AC. The inclined surface 17AC is inclined away from the first lead terminal 16 side surface of both sides of the wire connection portion 17AA toward the tip end surface of the wire connection portion 17AA. In a plan view, each of the inclined surfaces 12AC and 17AC faces the first die pad 30. In other words, in a plan view, each of the inclined surfaces 12AC and 17AC faces the first die pad 30. In a plan view, each of the inclined surfaces 12AC and 17AC faces the first chip 60. In a plan view, each of the inclined surfaces 12AC and 17AC faces the first chip 60.

[0304] Two first lead wires WB are connected to the wire connection portion 12AA. The first lead wire WB arranged closer to the first lead terminal 11 extends from the first bond portion of the first chip 60 so as to pass through the tip surface of the wire connection portion 12AA in a plan view. The first lead wire WB that has passed through the tip surface of the wire connection portion 12AA in a plan view is bonded to a portion of the wire connection portion 12AA that is closer to the first lead terminal 11 than the center of the wire connection portion 12AA in the Y direction. In other words, the second bond portion of this first lead wire WB is formed at a position closer to the first lead terminal 11 than the center of the wire connection portion 12AA in the Y direction.

[0305] In a plan view, the first lead wire WB connected to the wire connection portion 12AA and the inclined surface 12AC are perpendicular to each other. Here, if the angle formed between the first lead wire WB connected to the wire connection portion 12AA and the inclined surface 12AC is 85° or more and 95° or less, it can be said that the first lead wire WB connected to the wire connection portion 12AA and the inclined surface 12AC are perpendicular to each other. In the second embodiment, the inclined surface 12AC corresponds to "a side surface that intersects with the first lead wire WB connected to the wire connection portion 12AA in a plan view."

[0306] In plan view, the relationship between the first lead wire WB connected to the wire connection portion 12AA and the inclined surface 12AC is not limited to being orthogonal. In plan view, the first lead wire WB connected to the wire connection portion 12AA may extend so as to intersect with the inclined surface 12AC.

[0307] The first lead wire WB disposed closer to the first lead terminal 13 extends from the first bond portion of the first chip 60 so as to pass through the inclined surface 12AC of the wire connection portion 12AA in a plan view. The first lead wire WB that has passed through the inclined surface 12AC of the wire connection portion 12AA in a plan view is joined to a portion of the wire connection portion 12AA that is closer to the first lead terminal 13 than the center of the wire connection portion 12AA in the Y direction. In other words, the second bond portion of this first lead wire WB is formed at a position closer to the first lead terminal 13 than the center of the wire connection portion 12AA in the Y direction.

[0308] One first lead wire WB is connected to the wire connection portion 17AA. This first lead wire WB extends from the first bond portion of the first chip 60 so as to pass through the inclined surface 17AC of the wire connection portion 17AA. In plan view, the first lead wire WB that has passed through the inclined surface 17AC of the wire connection portion 17AA is bonded to the center of the wire connection portion 17AA in the Y direction. In other words, the second bond portion of this first lead wire WB is formed at the center position of the wire connection portion 17AA in the Y direction.

[0309] In a plan view, the first lead wire WB connected to the wire connection portion 17AA and the inclined surface 17AC are perpendicular to each other. Here, if the angle formed between the first lead wire WB connected to the wire connection portion 17AA and the inclined surface 17AC is 85° or more and 95° or less, it can be said that the first lead wire WB connected to the wire connection portion 17AA and the inclined surface 17AC are perpendicular to each other. In the second embodiment, the inclined surface 17AC corresponds to "a side surface that intersects with the first lead wire WB connected to the wire connection portion 17AA in a plan view."

[0310] In plan view, the relationship between the first lead wire WB connected to the wire connection portion 17AA and the inclined surface 17AC is not limited to being orthogonal. In plan view, the first lead wire WB connected to the wire connection portion 17AA may extend so as to intersect with the inclined surface 17AC.

[0311] As shown in FIG. 26 , the shapes of the wire connection portions 42AA, 45AA, and 46AA of the second lead terminals 42, 45, and 46 of the second frame 10B are different from those of the first embodiment. More specifically, the corner portion of the tip end of the wire connection portion 42AA closest to the second lead terminal 43 includes an inclined surface 42AC. The inclined surface 42AC slopes away from the second lead terminal 43 from the side surface of both sides of the wire connection portion 42AA that faces the second lead terminal 43 toward the tip end surface of the wire connection portion 42AA. In a plan view, the inclined surface 42AC faces the second die pad 50. In a plan view, the inclined surface 42AC can be said to face the second die pad 50 side. In a plan view, the inclined surface 42AC faces the second chip 70. In a plan view, the inclined surface 42AC can be said to face the second chip 70 side.

[0312] The length of the inclined surface 45AC of the wire connecting portion 45AA is shorter than the length of the inclined surface 45AC of the first embodiment. As a result, the length of the tip surface of the wire connecting portion 45AA (the length of the tip surface in the Y direction) is longer than the length of the tip surface of the wire connecting portion 45AA of the first embodiment. The length of the inclined surface 46AC of the wire connecting portion 46AA is shorter than the length of the inclined surface 46AC of the first embodiment. As a result, the length of the tip surface of the wire connecting portion 46AA (the length of the tip surface in the Y direction) is longer than the length of the tip surface of the wire connecting portion 46AA of the first embodiment.

[0313] One second lead wire WD is connected to the wire connection portion 42AA. In plan view, the second lead wire WD extends from the first bond portion of the second chip 70 so as to pass through the inclined surface 42AC of the wire connection portion 42AA. In plan view, the second lead wire WD that has passed through the inclined surface 42AC of the wire connection portion 42AA is bonded to the center of the wire connection portion 42AA in the Y direction. In other words, the second bond portion of this second lead wire WD is formed near the center position of the wire connection portion 42AA in the Y direction.

[0314] In a plan view, the second lead wire WD connected to the wire connection portion 42AA and the inclined surface 42AC are perpendicular to each other. Here, if the angle formed between the second lead wire WD connected to the wire connection portion 42AA and the inclined surface 42AC is 85° or more and 95° or less, it can be said that the second lead wire WD connected to the wire connection portion 42AA and the inclined surface 42AC are perpendicular to each other. In the second embodiment, the inclined surface 42AC corresponds to "a side surface that intersects with the second lead wire WD connected to the wire connection portion 42AA in a plan view."

[0315] In plan view, the relationship between the second lead wire WD connected to the wire connection portion 42AA and the inclined surface 42AC is not limited to being orthogonal. In plan view, the second lead wire WD connected to the wire connection portion 42AA may extend so as to intersect with the inclined surface 42AC.

[0316] One second lead wire WD is connected to the wire connection portion 45AA. In plan view, the second lead wire WD extends from the first bond portion of the second chip 70 so as to pass through the tip surface of the wire connection portion 45AA. The second lead wire WD that has passed through the tip surface of the wire connection portion 45AA in plan view is then bonded to the center of the wire connection portion 45AA in the Y direction. In other words, the second bond portion of this second lead wire WD is formed at the center position of the wire connection portion 45AA in the Y direction.

[0317] Two second lead wires WD are connected to the wire connection portion 46AA. Each of the two second lead wires WD extends from the first bond portion of the second chip 70 so as to pass through the tip surface of the wire connection portion 46AA in a plan view. The two second lead wires WD that pass through the tip surface of the wire connection portion 46AA in a plan view are bonded to portions of the wire connection portion 46AA closer to the second lead terminal 45 and closer to the second lead terminal 47 than the center of the wire connection portion 46AA in the Y direction. In other words, the second bond portions of these second lead wires WD are formed at positions closer to the second lead terminal 45 and closer to the second lead terminal 47 than the center of the wire connection portion 46AA in the Y direction.

[0318] [Effects] The signal transmission device 10 of the second embodiment has the following effects. (2-1) The first lead terminals 12, 17 include lead connection portions 12AB, 17AB extending in the X direction (first direction) that is orthogonal in plan view to the Y direction (second direction), which is the arrangement direction of the first lead terminals 11 to 18, and wire connection portions 12AA, 17AA that are provided contiguous to the lead connection portions 12AB, 17AB and extend in a direction intersecting the X direction with respect to the lead connection portions 12AB, 17AB. The wire connection portions 12AA, 17AA include inclined surfaces 12AC, 17AC that intersect in plan view with the first lead wires WB of the first lead terminals 12, 17 that are connected to the wire connection portions 12AA, 17AA.

[0319] According to this configuration, when viewed in a plane, the first lead wire WB extends so as to intersect with the inclined surfaces 12AC, 17AC of the wire connection portions 12AA, 17AA, making it easier to confirm the joining position of the first lead wire WB with the wire connection portions 12AA, 17AA compared to when the first lead wire WB extends roughly along the side surfaces of the wire connection portions 12AA, 17AA and enters from the corner portions of the wire connection portions 12AA.

[0320] (2-2) The second lead terminal 42 includes a lead connection portion 42AB extending in an X direction (first direction) perpendicular to the Y direction (second direction) in plan view, which is the arrangement direction of the second lead terminals 41 to 48, and a wire connection portion 42AA provided contiguous to the lead connection portion 42AB and extending in a direction intersecting the X direction with respect to the lead connection portion 42AB. The wire connection portion 42AA includes an inclined surface 42AC that intersects, in plan view, with the second lead wire WD of the second lead terminal 42 that is connected to the wire connection portion 42AA.

[0321] According to this configuration, the second lead wire WD extends so as to intersect with the inclined surface 42AC of the wire connection portion 42AA when viewed in a plane, making it easier to confirm the joining position of the second lead wire WD with the wire connection portion 42AA compared to when the second lead wire WD extends roughly along the side of the wire connection portion 42AA and enters from a corner portion of the wire connection portion 42AA.

[0322] 27 and 28, a signal transmission device 10 according to a third embodiment will be described. The signal transmission device 10 according to the third embodiment differs from the signal transmission device 10 according to the first embodiment in the configuration of the first frame 10A and the second frame 10B. In the following description, configurations that differ from the first embodiment will be described in detail, and components that are common to the first embodiment will be denoted by the same reference numerals and will not be described again.

[0323] The first frame 10A of the third embodiment differs in the configuration of the first lead terminals 12 to 17 among the first lead terminals 11 to 18. More specifically, as shown in FIG. 27 , the first inner lead portions 12A to 17A of the first lead terminals 12 to 17 have through holes 12AD to 17AD formed therein, penetrating the first inner lead portions 12A to 17A in their thickness direction (Z direction). In one example, the through holes 12AD to 17AD have a circular shape in plan view. In the third embodiment, the through holes 12AD to 17AD have the same diameter. Note that the shape and size of the through holes 12AD to 17AD in plan view can be changed as desired.

[0324] The through holes 12AD to 17AD are filled with sealing resin 90. In other words, the sealing resin 90 filled in the through holes 12AD to 17AD connects the sealing resin 90 provided closer to the sealing surface 91 (see FIG. 2) than the first inner lead portions 12A to 17A with the sealing resin 90 provided closer to the sealing back surface 92 (see FIG. 2) than the first inner lead portions 12A to 17A.

[0325] Here, the first lead terminals 11 and 18 are integrated with the first die pad 30 and therefore correspond to "first connection terminals." The first lead terminals 12 to 17 are arranged spaced apart from the first die pad 30 and therefore correspond to "first remote terminals." Because the through holes 12AD to 17AD are formed in the first lead terminals 12 to 17, it can be said that the first remote terminals have through holes that penetrate through the first remote terminals in the thickness direction. On the other hand, the first connection terminals do not have through holes.

[0326] 27 , the through hole 12AD is formed in a portion of the wire connection portion 12AA of the first inner lead portion 12A that is closer to the lead connection portion 12AB. The first lead wire WB corresponding to the wire connection portion 12AA is bonded to a portion of the wire connection portion 12AA that is closer to the first chip 60 than the through hole 12AD. The second bond portion of the first lead wire WB is disposed spaced apart from the through hole 12AD in the X direction in a plan view.

[0327] The through hole 13AD is formed in a portion of the wire connection portion 13AA of the first inner lead portion 13A that is closer to the lead connection portion 13AB. The first lead wire WB corresponding to the wire connection portion 13AA is bonded to a portion of the wire connection portion 13AA that is closer to the first chip 60 than the through hole 13AD. The second bond portion of the first lead wire WB is arranged spaced apart from the through hole 13AD in the X direction in a plan view.

[0328] The through hole 14AD is formed in a portion of the wire connection portion 14AA of the first inner lead portion 14A that is closer to the lead connection portion 14AB. The first lead wire WB corresponding to the wire connection portion 14AA is bonded to a portion of the wire connection portion 14AA that is closer to the first chip 60 than the through hole 14AD. The second bond portion of the first lead wire WB is arranged spaced apart from the through hole 14AD in the X direction in a plan view.

[0329] The through hole 15AD is formed in a portion of the wire connection portion 15AA of the first inner lead portion 15A that is closer to the lead connection portion 15AB. The first lead wire WB corresponding to the wire connection portion 15AA is bonded to a portion of the wire connection portion 15AA that is closer to the first chip 60 than the through hole 15AD. The second bond portion of the first lead wire WB is disposed spaced apart from the through hole 15AD in the X direction in a plan view.

[0330] The through hole 16AD is formed in a portion of the wire connection portion 16AA of the first inner lead portion 16A that is closer to the lead connection portion 16AB. The first lead wire WB corresponding to the wire connection portion 16AA is bonded to a portion of the wire connection portion 16AA that is closer to the first chip 60 than the through hole 16AD. The second bond portion of the first lead wire WB is arranged spaced apart from the through hole 16AD in the X direction in a plan view.

[0331] The through hole 17AD is formed in a portion of the wire connection portion 17AA of the first inner lead portion 17A that is closer to the lead connection portion 17AB. The first lead wire WB corresponding to the wire connection portion 17AA is bonded to a portion of the wire connection portion 17AA that is closer to the first chip 60 than the through hole 17AD. The second bond portion of the first lead wire WB is disposed spaced apart from the through hole 17AD in the X direction in a plan view.

[0332] The positions at which the through holes 12AD to 17AD are formed can be changed as desired. For example, the through holes 12AD to 17AD may be formed in the lead connection portions 12AB to 17AB. The through holes 12AD to 17AD may also be formed across the wire connection portions 12AA to 17AA and the lead connection portions 12AB to 17AB.

[0333] As shown in FIG. 28 , the second frame 10B of the third embodiment differs in the configuration of the second lead terminals 42 to 47 among the second lead terminals 41 to 48. More specifically, the second inner lead portions 42A to 47A of the second lead terminals 42 to 47 are formed with through holes 42AD to 47AD that penetrate the second inner lead portions 42A to 47A in their thickness direction (Z direction). In one example, the through holes 42AD to 47AD are circular in plan view. In the third embodiment, the through holes 42AD to 47AD have the same diameter. Furthermore, the diameter of the through holes 42AD to 47AD is the same as the diameter of the through holes 12AD to 17AD. Note that the shape and size of the through holes 42AD to 47AD in plan view can be freely changed.

[0334] The through holes 42AD to 47AD are filled with sealing resin 90. In other words, the sealing resin 90 filled in the through holes 42AD to 47AD connects the sealing resin 90 provided closer to the sealing surface 91 (see FIG. 2) than the second inner lead portions 42A to 47A with the sealing resin 90 provided closer to the sealing back surface 92 (see FIG. 2) than the second inner lead portions 42A to 47A.

[0335] Here, the second lead terminals 41, 48 are integrated with the second die pad 50 and therefore correspond to "second connection terminals." The second lead terminals 42 to 47 are disposed apart from the second die pad 50 and therefore correspond to "second remote terminals." Because the through holes 42AD to 47AD are formed in the second lead terminals 42 to 47, it can be said that the second remote terminals have through holes that penetrate through the second remote terminals in the thickness direction. On the other hand, the second connection terminals do not have through holes.

[0336] 28 , the through hole 42AD is formed in a portion of the wire connection portion 42AA of the second inner lead portion 42A that is closer to the lead connection portion 42AB. The second lead wire WD corresponding to the wire connection portion 42AA is bonded to a portion of the wire connection portion 42AA that is closer to the second chip 70 than the through hole 42AD. The second bond portion of the second lead wire WD is disposed spaced apart from the through hole 42AD in the X direction in a plan view.

[0337] The through hole 43AD is formed in a portion of the wire connection portion 43AA of the second inner lead portion 43A that is closer to the lead connection portion 43AB. The second lead wire WD corresponding to the wire connection portion 43AA is bonded to a portion of the wire connection portion 43AA that is closer to the second chip 70 than the through hole 43AD. The second bond portion of the second lead wire WD is arranged spaced apart from the through hole 43AD in the X direction in a plan view.

[0338] The through hole 44AD is formed in a portion of the wire connection portion 44AA of the second inner lead portion 44A that is closer to the lead connection portion 44AB. The second lead wire WD corresponding to the wire connection portion 44AA is bonded to a portion of the wire connection portion 44AA that is closer to the second chip 70 than the through hole 44AD. The second bond portion of the second lead wire WD is arranged spaced apart from the through hole 44AD in the X direction in a plan view.

[0339] The through hole 45AD is formed in a portion of the wire connection portion 45AA of the second inner lead portion 45A that is closer to the lead connection portion 45AB. The second lead wire WD corresponding to the wire connection portion 45AA is bonded to a portion of the wire connection portion 45AA that is closer to the second chip 70 than the through hole 45AD. The second bond portion of the second lead wire WD is arranged spaced apart from the through hole 45AD in the X direction in a plan view.

[0340] The through hole 46AD is formed in a portion of the wire connection portion 46AA of the second inner lead portion 46A that is closer to the lead connection portion 46AB. Each of the two second lead wires WD corresponding to the wire connection portion 46AA is bonded to a portion of the wire connection portion 46AA that is closer to the second chip 70 than the through hole 46AD. Each of the second bond portions of the two second lead wires WD is disposed spaced apart from the through hole 46AD in the X direction in a plan view.

[0341] The through hole 47AD is formed in a portion of the wire connection portion 47AA of the second inner lead portion 47A that is closer to the lead connection portion 47AB. The second lead wire WD corresponding to the wire connection portion 47AA is bonded to a portion of the wire connection portion 47AA that is closer to the second chip 70 than the through hole 47AD. The second bond portion of the second lead wire WD is arranged spaced apart from the through hole 47AD in the X direction in a plan view.

[0342] The positions of the through holes 42AD to 47AD can be changed as desired. For example, the through holes 42AD to 47AD may be formed in the lead connection portions 42AB to 47AB. The through holes 42AD to 47AD may also be formed across the wire connection portions 42AA to 47AA and the lead connection portions 42AB to 47AB.

[0343] [Advantages] The signal transmission device 10 of the third embodiment has the following advantages: (3-1) The first lead terminals 12 to 17 have through holes 12AD to 17AD. The through holes 12AD to 17AD are filled with a sealing resin 90.

[0344] According to this configuration, the sealing resin 90 filled in the through holes 12AD to 17AD can prevent the first lead terminals 12 to 17 from moving when an external force is applied to the first lead terminals 12 to 17. Therefore, it is possible to prevent force from being applied to the first lead wires WB due to the movement of the first lead terminals 12 to 17.

[0345] (3-2) The second lead terminals 42 to 47 have through holes 42AD to 47AD. The through holes 42AD to 47AD are filled with sealing resin 90. With this configuration, the sealing resin 90 filled in the through holes 42AD to 47AD can prevent the second lead terminals 42 to 47 from moving when an external force is applied to the second lead terminals 42 to 47. Therefore, it is possible to prevent force from being applied to the second lead wires WD due to movement of the second lead terminals 42 to 47.

[0346] 29 to 31, a signal transmission device 10 according to a fourth embodiment will be described. The signal transmission device 10 according to the fourth embodiment differs from the signal transmission device 10 according to the third embodiment in the configuration of the first frame 10A and the second frame 10B and the configuration of the wires. In the following description, the configuration that differs from the third embodiment will be described in detail, and components that are common to the third embodiment will be denoted by the same reference numerals and will not be described again.

[0347] The first frame 10A of the fourth embodiment is different from the third embodiment in the configuration of the first lead terminals 12 and 17 among the first lead terminals 11 to 18. More specifically, as shown in FIG. 29 , the through holes 12AD and 17AD (see FIG. 27 ) are omitted from the first inner lead portions 12A and 17A of the first lead terminals 12 and 17.

[0348] In other words, the first frame 10A includes two types of first lead terminals: first specific terminals (first lead terminals 13 to 16 in the fourth embodiment) having through holes formed in the first inner lead portions 12A to 17A of the first lead terminals 12 to 17, and second specific terminals (first lead terminals 12, 17 in the fourth embodiment) having no through holes formed therein.

[0349] In the fourth embodiment, the configuration of the second bond portion of the first lead wire WB differs depending on the first specified terminal and the second specified terminal. More specifically, a security bond WB1 is formed in the second bond portion of the first lead wire WB connected to the wire connection portions 12AA, 17AA of the first inner lead portions 12A, 17A of the first lead terminals 12, 17 serving as the second specified terminals. On the other hand, no security bond WB1 is formed in the second bond portion of the first lead wire WB connected to the wire connection portions 13AA-16AA of the first inner lead portions 13A-16A of the first lead terminals 13-16 serving as the first specified terminals.

[0350] That is, the plurality of first lead wires WB include first specified wires joined to first specified terminals (first lead terminals 13 to 16 in the fourth embodiment) and second specified wires joined to second specified terminals (first lead terminals 12 and 17 in the fourth embodiment). A security bond is formed at the joint (second bond portion) of the second specified wire joined to the second specified terminal.

[0351] The second frame 10B of the fourth embodiment is different from the third embodiment in the configuration of the second lead terminals 42, 46 among the second lead terminals 41 to 48. More specifically, as shown in Fig. 30, the through holes 42AD, 46AD are omitted from the second inner lead portions 42A, 46A of the second lead terminals 42, 46. In other words, the second frame 10B includes two types of second lead terminals: second lead terminals having through holes among the second lead terminals 42 to 47 (second lead terminals 43 to 45, 47 in the fourth embodiment) and second lead terminals not having through holes (second lead terminals 42, 46 in the fourth embodiment).

[0352] In other words, the second frame 10B includes two types of second lead terminals: third specific terminals (second lead terminals 43 to 45, 47 in the fourth embodiment) having through holes formed in the second inner lead portions 42A to 47A of the second lead terminals 42 to 47, and fourth specific terminals (second lead terminals 42, 46 in the fourth embodiment) having no through holes formed therein.

[0353] In the fourth embodiment, the configuration of the second bond portion of the second lead wire WD differs depending on the third specified terminal and the fourth specified terminal. More specifically, a security bond WD1 is formed in the second bond portion of the second lead wire WD connected to the wire connection portions 42AA, 46AA of the second inner lead portions 42A, 46A of the second lead terminals 42, 46 serving as the fourth specified terminals. On the other hand, no security bond WD1 is formed in the second bond portion of the second lead wire WD connected to the wire connection portions 43AA-45AA, 47AA of the second inner lead portions 43A-45A, 47A of the second lead terminals 43-45, 47 serving as the third specified terminals.

[0354] That is, the plurality of second lead wires WD include a third specified wire joined to a third specified terminal (second lead terminals 43 to 45, 47 in the fourth embodiment) and a fourth specified wire joined to a fourth specified terminal (second lead terminals 42, 46 in the fourth embodiment). A security bond is formed at a bond portion (second bond portion) of the fourth specified wire joined to the fourth specified terminal.

[0355] 31 shows a perspective view of the second bond portion of the second lead wire WD and its surroundings. Note that since the configuration of the second bond portion of the second lead wire WD and the configuration of the second bond portion of the first lead wire WB are the same, the configuration of the second bond portion of the second lead wire WD will be described in detail, and a detailed description of the configuration of the second bond portion of the first lead wire WB will be omitted.

[0356] 31 , the second bond portion of the second lead wire WD includes a joint portion WDP joined to the wire connection portion 46AA of the second lead terminal 46. The joint portion WDP is a portion that is crushed by being pressed against the wire connection portion 46AA by the wire bonding device. Therefore, the thickness of the joint portion WDP is smaller than the diameter of the second lead wire WD.

[0357] The security bond WD1 is formed, for example, by providing a stud bump SB on the bonding portion WDP. In one example, the stud bump SB is formed by ball bonding using a wire bonding device. The bonding portion WDP is sandwiched between the wire connection portion 46AA and the stud bump SB. As shown in FIG. 31 , the detailed structure of the stud bump SB is the same as that of the security bond WE1 of the second die pad wire WE of the first embodiment.

[0358] [Effects] The signal transmission device 10 of the fourth embodiment has the following effects: (4-1) Of the first lead terminals 12 to 17, the first lead terminals 12 and 17 do not have through holes 12AD and 17AD formed therein. A security bond WB1 is formed in the second bond portion of the first lead wire WB joined to the wire connection portion 12AA and 17AA of the first lead terminals 12 and 17.

[0359] With this configuration, even if an external force is applied to the first lead terminals 12, 17 and the first lead terminals 12, 17 move, applying force to the first lead wire WB, the security bond WB1 can prevent the first lead wire WB from peeling off from the wire connection portions 12AA, 17AA.

[0360] (4-2) Through holes 13AD to 16AD are formed in the first lead terminals 13 to 16 among the first lead terminals 12 to 17. No security bond is formed in the second bond portion of the first lead wire WB joined to the wire connection portions 13AA to 16AA of the first lead terminals 13 to 16.

[0361] With this configuration, the sealing resin 90 filled in the through holes 13AD-16AD suppresses movement of the first lead terminals 13-16, making it less likely that force will be applied to the first lead wires WB joined to the first lead terminals 13-16. Furthermore, there is no need to form security bonds on the first lead wires WB joined to the first lead terminals 13-16, simplifying the manufacturing process. This allows for a reduction in the manufacturing cost of the signal transmission device 10.

[0362] (4-3) Of the second lead terminals 42 to 47, the second lead terminals 42, 46 do not have through holes 42AD, 46AD formed therein. A security bond WD1 is formed in the second bond portion of the second lead wire WD joined to the wire connection portions 42AA, 46AA of the second lead terminals 42, 46.

[0363] According to this configuration, even if an external force is applied to the second lead terminals 42, 46 and the second lead terminals 42, 46 move, applying force to the second lead wire WD, the security bond WD1 can prevent the second lead wire WD from peeling off from the wire connection portions 42AA, 46AA.

[0364] (4-4) Through holes 43AD to 45AD, 47AD are formed in the second lead terminals 43 to 45, 47 out of the second lead terminals 42 to 47. No security bond is formed in the second bond portion of the second lead wire WD joined to the second lead terminals 43 to 45, 47.

[0365] With this configuration, the sealing resin 90 filled in the through holes 43AD-45AD, 47AD suppresses movement of the second lead terminals 43-45, 47, making it less likely that force will be applied to the second lead wires WD joined to the second lead terminals 43-45, 47. Furthermore, there is no need to form security bonds on the second lead wires WD joined to the second lead terminals 43-45, 47, simplifying the manufacturing process. This allows for a reduction in the manufacturing cost of the signal transmission device 10.

[0366] Fifth Embodiment A signal transmission device 10 of a fifth embodiment will be described with reference to Fig. 32. The signal transmission device 10 of the fifth embodiment differs from the signal transmission device 10 of the first embodiment in the configuration of the first frame 10A and the second frame 10B. In the following description, configurations that differ from the first embodiment will be described in detail, and components that are common to the first embodiment will be assigned the same reference numerals and their description will be omitted.

[0367] The first frame 10A and the second frame 10B of the fifth embodiment are different from those of the first embodiment in the shapes of the first die pad 30 and the second die pad 50. More specifically, the first die pad 30 includes a first tip side curved surface 35A and a second tip side curved surface 36A instead of the first tip side inclined portion 35 and the second tip side inclined portion 36. The second die pad 50 includes a third tip side curved surface 55A and a fourth tip side curved surface 56A instead of the third tip side inclined portion 55 and the fourth tip side inclined portion 56.

[0368] In the first die pad 30, the first tip curved surface 35A has a shape in which the corner portion between the first tip surface 31 and the first side surface 33 is rounded. In a plan view, the arc length of the first tip curved surface 35A is longer than the arc length of the first base curved surface 37A. In a plan view, the arc length of the first tip curved surface 35A is longer than the arc length of the first recess-side curved surface 38A. In addition, in a plan view, it can be said that the radius of curvature of the first tip curved surface 35A is larger than the radius of curvature of the first base curved surface 37A. In a plan view, it can be said that the radius of curvature of the first tip curved surface 35A is larger than the radius of curvature of the first recess-side curved surface 38A.

[0369] In one example, in a plan view, the arc length of first distal curved surface 35A is at least twice the arc length of first proximal curved surface 37A. In one example, in a plan view, the arc length of first distal curved surface 35A is at least five times the arc length of first proximal curved surface 37A. In one example, in a plan view, the arc length of first distal curved surface 35A is at most ten times the arc length of first proximal curved surface 37A.

[0370] In one example, in a plan view, the arc length of the first tip-side curved surface 35A is at least twice the arc length of the first recess-side curved surface 38A. In one example, in a plan view, the arc length of the first tip-side curved surface 35A is at least five times the arc length of the first recess-side curved surface 38A. In one example, in a plan view, the arc length of the first tip-side curved surface 35A is at most ten times the arc length of the first recess-side curved surface 38A.

[0371] In the first die pad 30, the second tip-side curved surface 36A has a shape in which the corner portion between the first tip surface 31 and the second side surface 34 is rounded. In a plan view, the arc length of the second tip-side curved surface 36A is longer than the arc length of the second base-side curved surface 37B. In a plan view, the arc length of the second tip-side curved surface 36A is longer than the arc length of the second recess-side curved surface 38B. In addition, in a plan view, it can be said that the radius of curvature of the second tip-side curved surface 36A is larger than the radius of curvature of the second base-side curved surface 37B. In a plan view, it can be said that the radius of curvature of the second tip-side curved surface 36A is larger than the radius of curvature of the second recess-side curved surface 38B.

[0372] In one example, in a plan view, the arc length of second distal curved surface 36A is at least twice the arc length of second proximal curved surface 37B. In one example, in a plan view, the arc length of second distal curved surface 36A is at least five times the arc length of second proximal curved surface 37B. In one example, in a plan view, the arc length of second distal curved surface 36A is at most ten times the arc length of second proximal curved surface 37B.

[0373] In one example, in a plan view, the arc length of the second tip-side curved surface 36A is at least twice the arc length of the second recess-side curved surface 38B. In one example, in a plan view, the arc length of the second tip-side curved surface 36A is at least five times the arc length of the second recess-side curved surface 38B. In one example, in a plan view, the arc length of the second tip-side curved surface 36A is not more than ten times the arc length of the second recess-side curved surface 38B.

[0374] In one example, in a plan view, the arc length of second distal curved surface 36A is equal to the arc length of first distal curved surface 35A. Here, if the difference between the arc length of second distal curved surface 36A and the arc length of first distal curved surface 35A is, for example, 10% or less of the arc length of second distal curved surface 36A, then the arc length of second distal curved surface 36A is equal to the arc length of first distal curved surface 35A.

[0375] In the second die pad 50, the third tip curved surface 55A has a shape in which the corner portion between the second tip surface 51 and the third side surface 53 is rounded. In a plan view, the arc length of the third tip curved surface 55A is longer than the arc length of the third base curved surface 57A. In a plan view, the arc length of the third tip curved surface 55A is longer than the arc length of the third recess-side curved surface 58A. In addition, in a plan view, it can be said that the radius of curvature of the third tip curved surface 55A is larger than the radius of curvature of the third base curved surface 57A. In a plan view, it can be said that the radius of curvature of the third tip curved surface 55A is larger than the radius of curvature of the third recess-side curved surface 58A.

[0376] In one example, in a plan view, the arc length of third distal curved surface 55A is at least twice the arc length of third proximal curved surface 57A. In one example, in a plan view, the arc length of third distal curved surface 55A is at least five times the arc length of third proximal curved surface 57A. In one example, in a plan view, the arc length of third distal curved surface 55A is at most ten times the arc length of third proximal curved surface 57A.

[0377] In one example, in a plan view, the arc length of third tip-side curved surface 55A is at least twice the arc length of third recess-side curved surface 58A. In one example, in a plan view, the arc length of third tip-side curved surface 55A is at least five times the arc length of third recess-side curved surface 58A. In one example, in a plan view, the arc length of third tip-side curved surface 55A is at most ten times the arc length of third recess-side curved surface 58A.

[0378] In one example, in a plan view, the arc length of the third tip side curved surface 55A is equal to the arc length of the first tip side curved surface 35A of the first die pad 30. Here, if the difference between the arc length of the third tip side curved surface 55A and the arc length of the first tip side curved surface 35A is, for example, 10% or less of the arc length of the third tip side curved surface 55A, it can be said that the arc length of the third tip side curved surface 55A is equal to the arc length of the first tip side curved surface 35A.

[0379] In the second die pad 50, the fourth tip curved surface 56A has a shape in which the corner portion between the second tip surface 51 and the fourth side surface 54 is rounded. In a plan view, the arc length of the fourth tip curved surface 56A is longer than the arc length of the fourth base curved surface 57B. In a plan view, the arc length of the fourth tip curved surface 56A is longer than the arc length of the fourth recess-side curved surface 58B. In addition, in a plan view, it can be said that the radius of curvature of the fourth tip curved surface 56A is larger than the radius of curvature of the fourth base curved surface 57B. In a plan view, it can be said that the radius of curvature of the fourth tip curved surface 56A is larger than the radius of curvature of the fourth recess-side curved surface 58B.

[0380] In one example, in a plan view, the arc length of fourth distal curved surface 56A is at least twice the arc length of fourth proximal curved surface 57B. In one example, in a plan view, the arc length of fourth distal curved surface 56A is at least five times the arc length of fourth proximal curved surface 57B. In one example, in a plan view, the arc length of fourth distal curved surface 56A is at most ten times the arc length of fourth proximal curved surface 57B.

[0381] In one example, in a plan view, the arc length of the fourth tip-side curved surface 56A is at least twice the arc length of the fourth recess-side curved surface 58B. In one example, in a plan view, the arc length of the fourth tip-side curved surface 56A is at least five times the arc length of the fourth recess-side curved surface 58B. In one example, in a plan view, the arc length of the fourth tip-side curved surface 56A is not more than ten times the arc length of the fourth recess-side curved surface 58B.

[0382] In one example, in a plan view, the arc length of the fourth distal curved surface 56A is equal to the arc length of the second distal curved surface 36A. Here, if the difference between the arc length of the fourth distal curved surface 56A and the arc length of the second distal curved surface 36A is, for example, 10% or less of the arc length of the fourth distal curved surface 56A, it can be said that the arc length of the fourth distal curved surface 56A is equal to the arc length of the second distal curved surface 36A.

[0383] In one example, in a plan view, the arc length of fourth distal curved surface 56A is equal to the arc length of third distal curved surface 55A. Here, if the difference between the arc length of fourth distal curved surface 56A and the arc length of third distal curved surface 55A is, for example, 10% or less of the arc length of fourth distal curved surface 56A, it can be said that the arc length of fourth distal curved surface 56A is equal to the arc length of third distal curved surface 55A.

[0384] The arc length of first distal curved surface 35A in plan view can be changed as desired as long as it is longer than the arc length of first proximal curved surface 37A in plan view. In one example, the arc length of first distal curved surface 35A in plan view may be equal to or shorter than the arc length of first recess-side curved surface 38A in plan view.

[0385] The arc length of the second distal curved surface 36A in plan view can be changed as desired as long as it is longer than the arc length of the second proximal curved surface 37B in plan view. In one example, the arc length of the second distal curved surface 36A in plan view may be equal to or shorter than the arc length of the second recess-side curved surface 38B in plan view.

[0386] The arc length of third distal curved surface 55A in plan view can be changed as desired as long as it is longer than the arc length of third proximal curved surface 57A in plan view. In one example, the arc length of third distal curved surface 55A in plan view may be equal to the arc length of third recess-side curved surface 58A in plan view, or may be shorter than the arc length of third recess-side curved surface 58A in plan view.

[0387] The arc length of fourth distal curved surface 56A in plan view can be changed as desired as long as it is longer than the arc length of fourth proximal curved surface 57B in plan view. In one example, the arc length of fourth distal curved surface 56A in plan view may be equal to or shorter than the arc length of fourth recess-side curved surface 58B in plan view.

[0388] In one example, the arc length of each of the first and second distal curved surfaces 35A and 36A in a plan view may be different from the arc length of each of the third and fourth distal curved surfaces 55A and 56A in a plan view. In one example, the arc length of each of the first and second distal curved surfaces 35A and 36A in a plan view may be shorter or longer than the arc length of each of the third and fourth distal curved surfaces 55A and 56A in a plan view.

[0389] [Effects] The signal transmission device 10 of the fifth embodiment has the following effects. (5-1) The first die pad 30 has a first tip-side curved surface 35A formed between the first tip-side surface 31 and the first side surface 33, a second tip-side curved surface 36A formed between the first tip-side surface 31 and the second side surface 34, a first base-side curved surface 37A formed between the first base-side surface 32 and the first side surface 33, and a second base-side curved surface 37B formed between the first base-side surface 32 and the second side surface 34. In a plan view, the arc lengths of both the first tip-side curved surface 35A and the second tip-side curved surface 36A are longer than the arc lengths of both the first base-side curved surface 37A and the second base-side curved surface 37B.

[0390] According to this configuration, the first tip-side curved surface 35A and the second tip-side curved surface 36A can mitigate electric field concentration at the corner portion of the tip of the first die pad 30 that is close to the second die pad 50. This makes it possible to avoid dielectric breakdown between the first die pad 30 and the second die pad 50, thereby improving the dielectric strength voltage of the signal transmission device 10.

[0391] (5-2) The second die pad 50 has a third tip-side curved surface 55A formed between the second tip-side surface 51 and the third side surface 53, a fourth tip-side curved surface 56A formed between the second tip-side surface 51 and the fourth side surface 54, a third base-side curved surface 57A formed between the second base-side surface 52 and the third side surface 53, and a fourth base-side curved surface 57B formed between the second base-side surface 52 and the fourth side surface 54. In a plan view, the arc lengths of both the third tip-side curved surface 55A and the fourth tip-side curved surface 56A are longer than the arc lengths of both the third base-side curved surface 57A and the fourth base-side curved surface 57B.

[0392] According to this configuration, the third tip-side curved surface 55A and the fourth tip-side curved surface 56A can mitigate electric field concentration at the corner portion of the tip of the second die pad 50 that is close to the first die pad 30. This makes it possible to avoid dielectric breakdown between the first die pad 30 and the second die pad 50, thereby improving the dielectric strength voltage of the signal transmission device 10.

[0393] Sixth Embodiment A signal transmission device 10 of a sixth embodiment will be described with reference to Fig. 33. The signal transmission device 10 of the sixth embodiment differs from the signal transmission device 10 of the fifth embodiment in the configuration of the first frame 10A and the second frame 10B. In the following description, configurations that differ from the fifth embodiment will be described in detail, and components that are common to the fifth embodiment will be assigned the same reference numerals and will not be described again.

[0394] The signal transmission device 10 of the sixth embodiment differs from the signal transmission device 10 of the fifth embodiment in the shape of the first die pad 30 of the first frame 10A and the shape of the second die pad 50 of the second frame 10B. More specifically, the first die pad 30 includes a first tip side inclined portion 35, a second tip side inclined portion 36, a first tip side curved surface 35B, and a second tip side curved surface 36B instead of the first tip side curved surface 35A and the second tip side curved surface 36A. The second die pad 50 includes a third tip side inclined portion 55, a fourth tip side inclined portion 56, a third tip side curved surface 55B, and a fourth tip side curved surface 56B instead of the third tip side curved surface 55A and the fourth tip side curved surface 56A.

[0395] In the first die pad 30, the first tip curved surface 35B has a shape in which a corner portion between the first tip surface 31 and the first tip inclined portion 35 is rounded. In a plan view, the arc length of the first tip curved surface 35B is longer than the arc length of the first base curved surface 37A (see FIG. 32 ). In a plan view, the arc length of the first tip curved surface 35B is longer than the arc length of the first recess-side curved surface 38A (see FIG. 32 ). In one example, the arc length of the first tip curved surface 35B in a plan view is at least twice the arc length of the first base curved surface 37A in a plan view.

[0396] The second distal curved surface 36B has a shape in which the corner portion between the first distal surface 31 and the second distal inclined portion 36 is rounded. In a plan view, the arc length of the second distal curved surface 36B is longer than the arc length of the second base curved surface 37B (see FIG. 32 ). In a plan view, the arc length of the second distal curved surface 36B is longer than the arc length of the second recess-side curved surface 38B (see FIG. 32 ). In one example, the arc length of the second distal curved surface 36B in a plan view is at least twice the arc length of the second base curved surface 37B in a plan view.

[0397] In one example, the arc length of the second distal curved surface 36B in a plan view is equal to the arc length of the first distal curved surface 35B in a plan view. Here, if the difference between the arc length of the second distal curved surface 36B in a plan view and the arc length of the first distal curved surface 35B in a plan view is, for example, within 10% of the arc length of the second distal curved surface 36B in a plan view, it can be said that the arc length of the second distal curved surface 36B in a plan view is equal to the arc length of the first distal curved surface 35B in a plan view.

[0398] In the second die pad 50, the third tip curved surface 55B has a shape in which the corner portion between the second tip surface 51 and the third tip inclined portion 55 is rounded. In a plan view, the arc length of the third tip curved surface 55B is longer than the arc length of the third base curved surface 57A (see FIG. 32 ). In a plan view, the arc length of the third tip curved surface 55B is longer than the arc length of the third recess-side curved surface 58A (see FIG. 32 ). In one example, the arc length of the third tip curved surface 55B in a plan view is at least twice the arc length of the third base curved surface 57A in a plan view.

[0399] The fourth distal curved surface 56B has a shape in which a corner portion between the second distal surface 51 and the fourth distal inclined portion 56 is rounded. In a plan view, the arc length of the fourth distal curved surface 56B is longer than the arc length of the fourth base curved surface 57B (see FIG. 32 ). In a plan view, the arc length of the fourth distal curved surface 56B is longer than the arc length of the fourth recess-side curved surface 58B (see FIG. 32 ). In one example, the arc length of the fourth distal curved surface 56B in a plan view is at least twice the arc length of the fourth base curved surface 57B in a plan view.

[0400] In one example, the arc length of fourth distal curved surface 56B in a plan view is equal to the arc length of third distal curved surface 55B in a plan view. Here, if the difference between the arc length of fourth distal curved surface 56B in a plan view and the arc length of third distal curved surface 55B in a plan view is, for example, within 10% of the arc length of fourth distal curved surface 56B in a plan view, it can be said that the arc length of fourth distal curved surface 56B in a plan view is equal to the arc length of third distal curved surface 55B in a plan view.

[0401] The arc length of first distal curved surface 35B in plan view can be changed as desired as long as it is longer than the arc length of first proximal curved surface 37A in plan view. In one example, the arc length of first distal curved surface 35B in plan view may be equal to or shorter than the arc length of first recess-side curved surface 38A in plan view.

[0402] The arc length of the second distal curved surface 36B in plan view can be changed as desired as long as it is longer than the arc length of the second proximal curved surface 37B in plan view. In one example, the arc length of the second distal curved surface 36B in plan view may be equal to or shorter than the arc length of the second recess-side curved surface 38B in plan view.

[0403] The arc length of third distal curved surface 55B in plan view can be changed as desired as long as it is longer than the arc length of third proximal curved surface 57A in plan view. In one example, the arc length of third distal curved surface 55B in plan view may be equal to or shorter than the arc length of third recess-side curved surface 58A in plan view.

[0404] The arc length of fourth distal curved surface 56B in plan view can be changed as desired as long as it is longer than the arc length of fourth proximal curved surface 57B in plan view. In one example, the arc length of fourth distal curved surface 56B in plan view may be equal to or shorter than the arc length of fourth recess-side curved surface 58B in plan view.

[0405] In another example, the arc length of each of the first distal curved surface 35B and the second distal curved surface 36B in a plan view may be different from the arc length of each of the third distal curved surface 55B and the fourth distal curved surface 56B in a plan view. In another example, the arc length of each of the first distal curved surface 35B and the second distal curved surface 36B in a plan view may be shorter or longer than the arc length of each of the third distal curved surface 55B and the fourth distal curved surface 56B in a plan view. Note that the signal transmission device 10 of the sixth embodiment provides the same effects as the fifth embodiment.

[0406] 34 to 41, a signal transmission device 10 according to a seventh embodiment will be described. The signal transmission device 10 according to the seventh embodiment differs from the signal transmission device 10 according to the first embodiment mainly in the configuration of each of the first chip 60 and the second chip 70. In the following description, configurations that differ from the first embodiment will be described in detail, and components that are common to the first embodiment will be assigned the same reference numerals and their description will be omitted.

[0407] Fig. 34 shows a schematic cross-sectional structure of the first die pad 30 and the first chip 60 cut along the XZ plane, and Fig. 35 shows a schematic cross-sectional structure of the first die pad 30 and the first chip 60 cut along the YZ plane. For this reason, the wires WA to WC and the sealing resin 90 are omitted from the cross-sectional structures of Figs. 34 and 35.

[0408] 34 and 35 , substrate 130 of first chip 60 has first to fourth substrate side surfaces 133 to 136 that connect substrate front surface 131 and substrate back surface 132. First substrate side surface 133 constitutes a part of first chip side surface 63 of first chip 60, second substrate side surface 134 constitutes a part of second chip side surface 64, third substrate side surface 135 constitutes a part of third chip side surface 65, and fourth substrate side surface 136 constitutes a part of fourth chip side surface 66.

[0409] The substrate 130 can be divided into a first portion 137 and a second portion 138 by a step portion 139. The first portion 137 is a portion of the substrate 130 that is closer to the first die pad 30. The second portion 138 is a portion that is provided on the first portion 137. As shown in FIGS. 34 and 35 , the step portion 139 is formed around the entire periphery of the substrate 130.

[0410] In one example, the thickness dimension (size in the Z direction) of first portion 137 is larger than the thickness dimension (size in the Z direction) of second portion 138. In one example, the thickness dimension of first portion 137 is more than twice the thickness dimension of second portion 138. In one example, the thickness dimension of first portion 137 is more than three times the thickness dimension of second portion 138. In one example, the thickness dimension of first portion 137 is less than four times the thickness dimension of second portion 138.

[0411] 34 and 35 , the first conductive bonding material SD1 is interposed between the first portion 137 and the first die pad 30 in the Z direction, and has a portion that protrudes from the first chip 60 in a direction perpendicular to the Z direction. This protruding portion forms a first fillet SDA between the first portion 137 and the first conductive bonding material SD1. The first fillet SDA is not formed in the second portion 138 due to a step portion 139. In the example shown in FIGS. 34 and 35 , the first fillet SDA is formed over the entire first portion 137 in the Z direction.

[0412] The height dimension (size in the Z direction) of the first fillet SDA can be changed as desired as long as it is lower than the step portion 139. In one example, the height dimension of the first fillet SDA may be approximately half the thickness dimension of the first portion 137.

[0413] Furthermore, the position of the step portion 139 in the first chip 60 in the Z direction can be changed as desired. That is, the relationship between the thickness of the first portion 137 and the thickness of the second portion 138 can be changed as desired. In one example, the thickness of the first portion 137 may be equal to the thickness of the second portion 138. In one example, the thickness of the first portion 137 is ½ or less of the thickness of the second portion 138. In one example, the thickness of the first portion 137 is ⅓ or less of the thickness of the second portion 138. In one example, the thickness of the first portion 137 is ¼ or more of the thickness of the second portion 138. In one example, the thickness of the first portion 137 is ¼ or more and ¾ or less of the thickness (size in the Z direction) of the first chip 60.

[0414] The width H1 of the step portion 139 is equal to each other on the first to fourth substrate side surfaces 133 to 136. The width H1 of the step portion 139 is, for example, about 3 μm. Here, the width H1 of the step portion 139 can be defined, for example, by the distance between a portion of the first substrate side surface 133 corresponding to the first portion 137 and a portion corresponding to the second portion 138.

[0415] Fig. 36 shows a schematic cross-sectional structure of the second die pad 50 and the second chip 70 taken along the XZ plane, and Fig. 37 shows a schematic cross-sectional structure of the second die pad 50 and the second chip 70 taken along the YZ plane. For this reason, the wires WD, WE and the sealing resin 90 are omitted from the cross-sectional structures of Fig. 36 and Fig. 37.

[0416] 36 and 37 , the second chip 70 mounted on the second die pad 50 includes a substrate 230. The substrate 230 is formed, for example, of a semiconductor substrate. The substrate 230 is a semiconductor substrate formed of a material containing silicon. Note that a wide bandgap semiconductor or a compound semiconductor may be used as the semiconductor substrate for the substrate 230. Furthermore, instead of a semiconductor substrate, an insulating substrate formed of a material containing glass or an insulating substrate formed of a material containing ceramics such as alumina may be used as the substrate 230.

[0417] The wide bandgap semiconductor is a semiconductor substrate having a bandgap of 2.0 eV or greater. The wide bandgap semiconductor may be silicon carbide. The compound semiconductor may be a III-V compound semiconductor. The compound semiconductor may include at least one of aluminum nitride, indium nitride, gallium nitride, and gallium arsenide.

[0418] The substrate 230 of the second chip 70 has first to fourth substrate side surfaces 233 to 236 that connect the substrate front surface 231 and the substrate back surface 232. The first substrate side surface 233 constitutes a part of the first chip side surface 73 of the second chip 70, the second substrate side surface 234 constitutes a part of the second chip side surface 74, the third substrate side surface 235 constitutes a part of the third chip side surface 75, and the fourth substrate side surface 236 constitutes a part of the fourth chip side surface 76.

[0419] The substrate 230 can be divided into a first portion 237 and a second portion 238 by a step portion 239. The first portion 237 is a portion of the substrate 230 that is closer to the second die pad 50. The second portion 238 is a portion that is provided on the first portion 237. As shown in FIGS. 36 and 37 , the step portion 239 is formed around the entire periphery of the substrate 230.

[0420] In one example, the thickness dimension (size in the Z direction) of the first portion 237 is larger than the thickness dimension (size in the Z direction) of the second portion 238. In one example, the thickness dimension of the first portion 237 is more than twice the thickness dimension of the second portion 238. In one example, the thickness dimension of the first portion 237 is more than three times the thickness dimension of the second portion 238. In one example, the thickness dimension of the first portion 237 is less than four times the thickness dimension of the second portion 238.

[0421] 36 and 37 , the second conductive bonding material SD2 is interposed between the first portion 237 and the second die pad 50 in the Z direction, and has a portion that protrudes from the second chip 70 in a direction perpendicular to the Z direction. This protruding portion forms a second fillet SDB between the first portion 237 and the second conductive bonding material SD2. The second fillet SDB is not formed in the second portion 238 due to a step portion 239. In the example shown in FIGS. 36 and 37 , the second fillet SDB is formed over the entire first portion 237 in the Z direction.

[0422] The height dimension (size in the Z direction) of the second fillet SDB can be changed as desired as long as it is lower than the step portion 239. In one example, the height dimension of the second fillet SDB may be approximately half the thickness dimension of the first portion 237.

[0423] Furthermore, the position of the step portion 239 in the second chip 70 in the Z direction can be changed as desired. That is, the relationship between the thickness of the first portion 237 and the thickness of the second portion 238 can be changed as desired. In one example, the thickness of the first portion 237 may be equal to the thickness of the second portion 238. In one example, the thickness of the first portion 237 is ½ or less of the thickness of the second portion 238. In one example, the thickness of the first portion 237 is ⅓ or less of the thickness of the second portion 238. In one example, the thickness of the first portion 237 is ¼ or more of the thickness of the second portion 238. In one example, the thickness of the first portion 237 is ¼ or more and ¾ or less of the thickness (size in the Z direction) of the second chip 70.

[0424] The width H2 of the step portion 239 is equal to each other on the first to fourth substrate side surfaces 233 to 236. The width H2 of the step portion 239 is, for example, about 3 μm. Here, the width H2 of the step portion 239 can be defined, for example, by the distance between a portion of the first substrate side surface 233 corresponding to the first portion 237 and a portion of the first substrate side surface 233 corresponding to the second portion 238.

[0425] [Method for Manufacturing First Chip] An example of a manufacturing process for the first chip 60 will be described with reference to FIGS. 38 to 41 . The method for manufacturing the first chip 60 includes the steps of preparing a substrate 830, forming an element insulating layer 850 on the substrate 830, forming a passivation film 861, forming a protective film 862, and singulating. An overview of each step will be described below. Note that FIGS. 38 to 41 show a schematic cross-sectional structure of the first chip 60. In FIGS. 39 to 41 , the hatched lines of the passivation film 861 and the protective film 862 have been omitted to facilitate understanding of the drawings. Furthermore, since the second chip 70 is manufactured in the same manner as the first chip 60, an example of a manufacturing process for the second chip 70 will not be described here.

[0426] 38, in the step of preparing a substrate 830, a substrate 830 including a plurality of substrates 130 (see FIG. 34) is prepared. Here, in regions of the substrate 830 corresponding to each of the plurality of substrates 130, the transmitting unit 301, the transmitting / receiving unit 302, the PWM generating unit 303, the logic unit 304, the UVLO unit 305, the resistor 306, the first switching element 307, and the second switching element 308 shown in FIG. 14 are formed.

[0427] As shown in FIG. 39, in the process of forming an element insulating layer 850 on a substrate 830, SiO 2 is deposited on a substrate surface 831 of the substrate 830 by, for example, a CVD method. ２ The film is laminated. ２ The film is a film that constitutes the element insulating layer 850. The element insulating layer 850 is made of, for example, a plurality of SiO ２ It is composed of a laminated film structure.

[0428] Although not shown, a step of forming the first to fourth back surface side coils 111B to 114B by, for example, sputtering and etching is carried out during the step of forming the element insulating layer 850 on the substrate 830. Then, after the step of forming the first to fourth back surface side coils 111B to 114B is carried out, the step of forming the element insulating layer 850 on the substrate 830 is carried out again.

[0429] Although not shown, after the element insulating layer 850 is formed, a process is carried out in which the first to fourth surface side coils 111A to 114A and the first to third electrode pads 67 to 69 are formed by sputtering and etching.

[0430] Subsequently, in the step of forming the passivation film 861, the passivation film 861 is formed by, for example, a CVD method on the element insulating layer 850. Although not shown, the passivation film 861 also covers the second to fourth surface-side coils 112A to 114A and the first to third electrode pads 67 to 69.

[0431] Subsequently, in the step of forming the protective film 862, the protective film 862 is formed on the passivation film 861 by, for example, a CVD method. The protective film 862 is formed over the entire surface of the passivation film 861, for example.

[0432] Subsequently, although not shown, openings are formed by, for example, etching in positions that overlap with portions of the first to third electrode pads 67 to 69 in both the protective film 862 and the passivation film 861. As a result, portions of the first to third electrode pads 67 to 69 are exposed in the Z direction from both the protective film 862 and the passivation film 861.

[0433] 40 and 41 , the singulation process includes a first dicing process and a second dicing process. As shown in FIG. 40 , in the first dicing process, the substrate 830 is first placed on the dicing tape DT. The back surface 832 of the substrate 830 is in contact with the dicing tape DT. Next, the first dicing blade DB1 cuts the protective film 862, the passivation film 861, and the element insulating layer 850, and also cuts a portion of the substrate 830 in the Z direction. As a result, a recess 833 is formed in the substrate 830.

[0434] 41, in the second dicing step, the substrate 830 is cut by a second dicing blade DB2. The second dicing blade DB2 is a blade that is narrower than the first dicing blade DB1. The second dicing blade DB2 cuts the substrate 830 from the recess 833 of the substrate 830. As a result, a step portion 839 is formed in the substrate 830. Thereafter, the dicing tape DT is removed. Through the above steps, the first chip 60 is manufactured.

[0435] [Effects] The signal transmission device 10 of the seventh embodiment has the following effects: (7-1) The substrate 130 of the first chip 60 has a first portion 137 including the substrate back surface 132, a second portion 138 provided on the first portion 137, and a step portion 139 formed so that the second portion 138 is positioned inside the substrate 130 with respect to the first portion 137.

[0436] According to this configuration, when the first chip 60 is mounted on the first die pad 30 using the first conductive bonding material SD1, the step portion 139 can prevent the first conductive bonding material SD1 from creeping up to the chip surface 61 of the first chip 60.

[0437] (7-2) The substrate 230 of the second chip 70 has a first portion 237 including the back surface 232 of the substrate, a second portion 238 provided on the first portion 237, and a step portion 239 formed so that the second portion 238 is positioned inside the substrate 230 relative to the first portion 237.

[0438] According to this configuration, when the second chip 70 is mounted on the second die pad 50 using the second conductive bonding material SD2, the step portion 239 can prevent the second conductive bonding material SD2 from creeping up to the chip surface 71 of the second chip 70.

[0439] Eighth Embodiment A signal transmission device 10 of an eighth embodiment will be described with reference to Fig. 42. The signal transmission device 10 of the eighth embodiment differs from the signal transmission device 10 of the first embodiment in that the conductive members 10D and 10E are omitted. In the following description, configurations that differ from the first embodiment will be described in detail, and components that are common to the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0440] 42 , the signal transmission device 10 does not include conductive members 10D and 10E (see FIG. 7 ). Therefore, the conductive member 10D is not exposed from the third sealing side surface 95 of the sealing resin 90. Furthermore, the conductive member 10E is not exposed from the fourth sealing side surface 96 of the sealing resin 90. In this way, both the third sealing side surface 95 and the fourth sealing side surface 96 are formed only from the resin material that constitutes the sealing resin 90.

[0441] Furthermore, due to the omission of conductive members 10D and 10E, recess 95D (see FIG. 7 ) is omitted from third sealing side surface 95, and recess 96D (see FIG. 7 ) is omitted from fourth sealing side surface 96. That is, the portion of third sealing side surface 95 between third front surface side surface 95A and third back surface side surface 95B forms a flat surface along the XZ plane over the entire X direction. The portion of fourth sealing side surface 96 between fourth front surface side surface 96A and fourth back surface side surface 96B forms a flat surface along the XZ plane over the entire X direction.

[0442] [Effects] The signal transmission device 10 of the eighth embodiment has the following effects: (8-1) Both the third sealing side surface 95 and the fourth sealing side surface 96 of the sealing resin 90 are formed only by the sealing resin 90, with no conductive member exposed.

[0443] This configuration can prevent static electricity and the like from entering the sealing resin 90 via the conductive member, compared to a configuration in which the conductive member is exposed on at least one of the third sealing side surface 95 and the fourth sealing side surface 96. Furthermore, since the conductive member is not exposed, a large insulation distance can be secured between the first lead terminals 11 to 18 and the second lead terminals 41 to 48. This can improve the dielectric strength of the signal transmission device 10.

[0444] 43 to 49, a signal transmission device 10 according to a ninth embodiment will be described. The signal transmission device 10 according to the ninth embodiment differs from the signal transmission device 10 according to the first embodiment mainly in the configurations of the first frame 10A, the second frame 10B, the first chip 60, and the second chip 70. In the following description, configurations that differ from the first embodiment will be described in detail, and components that are common to the first embodiment will be assigned the same reference numerals and will not be described again.

[0445] 43 , unlike the first embodiment, the ninth embodiment includes a signal transmission device 10 having four first lead terminals 11 to 14 protruding from a first sealing side surface 93 of the sealing resin 90 and four second lead terminals 41 to 44 protruding from a second sealing side surface 94. That is, the ninth embodiment has fewer first lead terminals and second lead terminals than the first embodiment.

[0446] Of the first lead terminals 11 to 14, the configuration of the first outer lead portions 11B to 14B outside the sealing resin 90 is the same as the configuration of the first outer lead portions 11B to 14B in the first embodiment. Of the second lead terminals 41 to 44, the configuration of the second outer lead portions 41B to 44B outside the sealing resin 90 is the same as the configuration of the second outer lead portions 41B to 44B in the first embodiment. Therefore, detailed descriptions of the configurations of the first outer lead portions 11B to 14B and second outer lead portions 41B to 44B will be omitted. Furthermore, since the configuration of the sealing resin 90 is the same as the configuration of the sealing resin 90 in the first embodiment, detailed descriptions thereof will be omitted.

[0447] 44 , as described above, in the ninth embodiment, the first frame 10A, unlike the first embodiment, includes four first lead terminals 11 to 14. The first lead terminals 11 to 14 are arranged spaced apart from one another in the Y direction. The first lead terminals 11 to 14 are arranged in the order of first lead terminals 11, 12, 13, 14 from the fourth sealing side surface 96 toward the third sealing side surface 95.

[0448] The first lead terminal 14 is connected to the first die pad 30. In one example, the first lead terminal 14 is integrated with the first die pad 30. The first lead terminals 11 to 13 are arranged closer to the first sealing side surface 93 of the first die pad 30 and spaced apart from the first die pad 30.

[0449] When viewed from the X direction, the first die pad 30 has a size in the Y direction such that it overlaps with all of the first lead terminals 11 to 14. In the ninth embodiment, the size of the first die pad 30 in the Y direction is larger than the distance in the Y direction between the edge of the first lead terminal 11 on the fourth sealing side surface 96 side and the edge of the first lead terminal 14 on the third sealing side surface 95 side.

[0450] The first die pad 30 of the ninth embodiment differs from the first embodiment in the configuration of the first base end surface 32. The protruding portion 32C is omitted from the first base end surface 32. Therefore, the recess 32A includes one side surface 32AA constituting the protruding portion 32B and a bottom surface 32AB.

[0451] The first die pad 30 of the ninth embodiment includes a suspension lead portion 32D. The suspension lead portion 32D is disposed closer to the fourth sealing side surface 96 than the first lead terminals 11 to 14. In one example, the suspension lead portion 32D extends in the X direction from the first base end surface 32 toward the first sealing side surface 93. The suspension lead portion 32D is exposed from the first sealing side surface 93. The second recess-side curved surface 38B is formed between the suspension lead portion 32D and the bottom surface 32AB of the recess 32A. The configuration of the plating layer 29 and the area where it is formed on the first die pad 30 are the same as those of the plating layer 29 of the first embodiment (see FIG. 9 ).

[0452] The first chip 60 mounted on the first die pad 30 is formed in a flat plate shape. In plan view, the first chip 60 has a rectangular shape with the X direction as the short side direction and the Y direction as the long side direction. The first chip 60 is mounted on the first die pad 30 with a first conductive bonding material SD1. More specifically, the first chip 60 is die-bonded to the first die pad 30.

[0453] The first chip 60 is disposed in a position of the first die pad 30 closer to the second die pad 50 in the X direction. In other words, in a plan view, the distance in the X direction between the first chip 60 and the first tip surface 31 of the first die pad 30 is smaller than the distance in the X direction between the first chip 60 and the bottom surface 32AB of the recess 32A in the first die pad 30.

[0454] The first chip 60 is disposed at a position on the first die pad 30 closer to the third sealing side surface 95 in the Y direction. That is, in a plan view, the distance between the first chip 60 and the first side surface 33 of the first die pad 30 is smaller than the distance between the first chip 60 and the second side surface 34 of the first die pad 30. When viewed from the X direction, the first chip 60 is disposed at a position overlapping the first lead terminals 12 and 13. When viewed from the X direction, the first chip 60 can also be said to be disposed closer to the fourth sealing side surface 96 than the first lead terminal 14. When viewed from the X direction, the first chip 60 can also be said to be disposed closer to the third sealing side surface 95 than the first lead terminal 11.

[0455] In the ninth embodiment, the second frame 10B, unlike the first embodiment, includes four second lead terminals 41 to 44. The second lead terminals 41 to 44 are arranged spaced apart from one another in the Y direction. The second lead terminals 41 to 44 are arranged in this order from the third sealing side surface 95 to the fourth sealing side surface 96.

[0456] The second lead terminal 41 is connected to the second die pad 50. In one example, the second lead terminal 41 is integrated with the second die pad 50. The second lead terminals 42 to 44 are arranged closer to the second sealing side surface 94 with respect to the second die pad 50 and spaced apart from the second die pad 50.

[0457] When viewed from the X direction, the second die pad 50 has a size in the Y direction such that it overlaps with all of the second lead terminals 41 to 44. In the ninth embodiment, the size of the second die pad 50 in the Y direction is larger than the distance in the Y direction between the edge of the second lead terminal 41 on the third sealing side surface 95 side and the edge of the second lead terminal 44 on the fourth sealing side surface 96 side.

[0458] The second die pad 50 of the ninth embodiment differs from the first embodiment in the configuration of the second base end surface 52. The protruding portion 52B is omitted from the second base end surface 52. Therefore, the recess 52A includes one inner side surface 52AA constituting the protruding portion 52C and a bottom surface 52AB.

[0459] The second die pad 50 of the ninth embodiment includes a suspension lead portion 52D. The suspension lead portion 52D is arranged closer to the fourth sealing side surface 96 than the second lead terminals 41 to 44. In one example, the suspension lead portion 52D extends in the X direction from the second base end surface 52 toward the second sealing side surface 94. The suspension lead portion 52D is exposed from the second sealing side surface 94. The fourth recess-side curved surface 58B is formed between the suspension lead portion 52D and the bottom surface 52AB of the recess 52A.

[0460] The second chip 70 mounted on the second die pad 50 is formed in a flat plate shape. In plan view, the second chip 70 has a rectangular shape with the X direction as the short side and the Y direction as the long side. The area of ​​the second chip 70 in plan view is larger than the area of ​​the first chip 60 in plan view. The second chip 70 is mounted on the second die pad 50 by a second conductive bonding material SD2. More specifically, the second chip 70 is die-bonded to the second die pad 50.

[0461] The second chip 70 is disposed in a position of the second die pad 50 closer to the first die pad 30 in the X direction. In other words, in a plan view, the distance in the X direction between the second chip 70 and the second tip surface 51 of the second die pad 50 is smaller than the distance in the X direction between the second chip 70 and the bottom surface 52AB of the recess 52A in the second die pad 50.

[0462] The second chip 70 is disposed at a position closer to the third sealing side surface 95 of the second die pad 50 in the Y direction. That is, in a plan view, the distance between the second chip 70 and the third side surface 53 of the second die pad 50 is smaller than the distance between the second chip 70 and the fourth side surface 54 of the second die pad 50. When viewed from the X direction, the second chip 70 is disposed at a position overlapping the second lead terminal 42. When viewed from the X direction, the second chip 70 can also be said to be disposed closer to the fourth sealing side surface 96 than the second lead terminal 41. When viewed from the X direction, the second chip 70 can also be said to be disposed closer to the third sealing side surface 95 than the second lead terminal 44. When viewed from the X direction, the second chip 70 can also be said to be disposed closer to the third sealing side surface 95 than the second lead terminal 43.

[0463] When viewed from the X direction, the second chip 70 is disposed in a position that partially overlaps with the first chip 60. When viewed from the X direction, the second chip 70 is disposed offset toward the third sealing side surface 95 relative to the first chip 60. In other words, when viewed from the X direction, the first chip 60 is disposed offset toward the fourth sealing side surface 96 relative to the second chip 70.

[0464] The detailed configuration of each of the first lead terminals 11 to 14 will be described. As shown in Fig. 45, the first lead terminals 11 to 14 include first inner lead portions 11A to 14A and first outer lead portions 11B to 14B provided in a sealing resin 90. The configuration of the first outer lead portions 11B to 14B is the same as that of the first outer lead portions 11B to 14B in the first embodiment. The configuration of the first inner lead portions 11A to 14A will be described below.

[0465] When viewed from the X direction, the first inner lead portions 11A to 13A are arranged at positions overlapping with the recessed portion 32A of the first die pad 30. The tip portions of the first inner lead portions 11A to 13A are arranged within the recessed portion 32A of the first die pad 30. The first inner lead portions 11A to 13A are arranged between the protruding portion 32B and the suspension lead portion 32D in the Y direction. The first inner lead portion 14A is arranged closer to the third sealing side surface 95 than the recessed portion 32A of the first die pad 30.

[0466] Unlike the first embodiment, the first inner lead portion 11A is disposed at a distance from the first die pad 30. The first inner lead portion 11A has a substantially L-shape in plan view. The first inner lead portion 11A includes a wire connection portion 11AA and a lead connection portion 11AB extending from the wire connection portion 11AA toward the first sealing side surface 93. The lead connection portion 11AB is connected to the first outer lead portion 11B.

[0467] The wire connection portion 11AA is disposed in the recess 32A of the first die pad 30. In a plan view, the wire connection portion 11AA has a generally rectangular shape with the Y direction as its longitudinal direction and the X direction as its lateral direction. The wire connection portion 11AA extends in the Y direction from the lead connection portion 11AB. The wire connection portion 11AA extends from the lead connection portion 11AB toward the first inner lead portion 12A. A corner portion of the tip of the wire connection portion 11AA near the suspension lead portion 32D includes a curved surface 11AE.

[0468] The lead connection portion 11AB is disposed closer to the first sealing side surface 93 than the recess 32A of the first die pad 30. In a plan view, the lead connection portion 11AB extends in the X direction. In one example, the size of the lead connection portion 11AB in the Y direction is smaller than the size of the wire connection portion 11AA in the Y direction.

[0469] The first inner lead portion 12A extends along the X direction and includes a wire connection portion 12AA and a lead connection portion 12AB extending from the wire connection portion 12AA toward the first sealing side surface 93. The lead connection portion 12AB is connected to the first outer lead portion 12B.

[0470] The wire connection portion 12AA is disposed in the recess 32A of the first die pad 30. In a plan view, the shape of the wire connection portion 12AA is a substantially rectangular shape with the Y direction as the longitudinal direction and the X direction as the lateral direction. In a plan view, the wire connection portion 12AA extends in the Y direction. In a plan view, the portion of the wire connection portion 12AA closer to the lead connection portion 12AB is tapered such that the width dimension (size in the Y direction) of the wire connection portion 12AA decreases toward the lead connection portion 12AB. A corner portion of the tip of the wire connection portion 12AA closer to the wire connection portion 11AA includes a curved surface 12AE.

[0471] The lead connection portion 12AB is disposed closer to the first sealing side surface 93 than the recess 32A of the first die pad 30. In a plan view, the lead connection portion 12AB extends in the X direction. In one example, the size of the lead connection portion 12AB in the Y direction is smaller than the size of the wire connection portion 12AA in the Y direction.

[0472] The first inner lead portion 13A has a substantially T-shape in plan view. The first inner lead portion 13A includes a wire connection portion 13AA and a lead connection portion 13AB extending from the wire connection portion 13AA toward the first sealing side surface 93. The lead connection portion 13AB is connected to the first outer lead portion 13B.

[0473] The wire connection portion 13AA is disposed in the recess 32A of the first die pad 30. In a plan view, the wire connection portion 13AA has a generally rectangular shape with the Y direction as its longitudinal direction and the X direction as its transverse direction. In a plan view, the wire connection portion 13AA extends in the Y direction. In a plan view, a portion of the wire connection portion 13AA closer to the lead connection portion 13AB is tapered such that the width (size in the Y direction) of the wire connection portion 13AA decreases toward the lead connection portion 13AB. A corner portion of the tip of the wire connection portion 13AA closer to the wire connection portion 12AA includes a curved surface 13AE. In the example shown in FIG. 45 , the shape of the first lead terminal 12 in a plan view is the same as the shape of the first lead terminal 13 in a plan view.

[0474] The lead connection portion 13AB is disposed closer to the first sealing side surface 93 than the recess 32A of the first die pad 30. In a plan view, the lead connection portion 13AB extends in the X direction. In one example, the size of the lead connection portion 13AB in the Y direction is smaller than the size of the wire connection portion 13AA in the Y direction.

[0475] In this way, the lead connection portions 11AB to 13AB correspond to the "first portion of the first lead terminal," and the wire connection portions 11AA to 13AA correspond to the "second portion of the first lead terminal." The X direction in which the lead connection portions 11AB to 13AB extend corresponds to the "first direction," and the Y direction in which the wire connection portions 11AA to 13AA extend corresponds to the "second direction." In the ninth embodiment, the wire connection portions 11AA to 13AA extend in a direction perpendicular to the direction in which the lead connection portions 11AB to 13AB extend in a plan view, but this is not limited to this. It is sufficient that the wire connection portions 11AA to 13AA extend in a direction intersecting the direction in which the lead connection portions 11AB to 13AB extend in a plan view. In other words, the second direction is not limited to a direction perpendicular to the first direction in a plan view, but may be any direction intersecting the first direction.

[0476] Unlike the first embodiment, the first inner lead portion 14A is connected to the first base end surface 32 of the first die pad 30. More specifically, the first inner lead portion 14A is connected to the protruding portion 32B of the first die pad 30. The first inner lead portion 14A extends along the X direction. The width dimension (size in the Y direction) of the first inner lead portion 14A is smaller than the width dimension (size in the Y direction) of the protruding portion 32B. The first inner lead portion 14A is disposed closer to the fourth sealing side surface 96 (closer to the first inner lead portion 13A) than the center of the protruding portion 32B in the Y direction.

[0477] A detailed configuration of each of the second lead terminals 41 to 44 will be described. As shown in Fig. 46, the second lead terminals 41 to 44 include second inner lead portions 41A to 44A and second outer lead portions 41B to 44B provided in the sealing resin 90. The configuration of the second inner lead portions 41A to 44A will be described below.

[0478] When viewed from the X direction, the second inner lead portions 42A to 44A are arranged at positions that overlap the recessed portion 52A of the second die pad 50. The tip portions of the second inner lead portions 42A to 44A are arranged within the recessed portion 52A of the second die pad 50. The second inner lead portion 41A is arranged closer to the third sealing side surface 95 than the recessed portion 52A of the second die pad 50.

[0479] The second inner lead portion 41A is connected to the second base end surface 52 of the second die pad 50. More specifically, the second inner lead portion 41A is connected to the protruding portion 52B of the second die pad 50. The second inner lead portion 41A extends along the X direction. The width dimension (size in the Y direction) of the second inner lead portion 41A is smaller than the width dimension (size in the Y direction) of the protruding portion 52B. The second inner lead portion 41A is positioned closer to the fourth sealing side surface 96 (closer to the second inner lead portion 42A) than the center of the protruding portion 52B in the Y direction.

[0480] The second inner lead portion 42A has a substantially T-shape in plan view. The second inner lead portion 42A includes a wire connection portion 42AA and a lead connection portion 42AB extending from the wire connection portion 42AA toward the second sealing side surface 94. The lead connection portion 42AB is connected to the second outer lead portion 42B.

[0481] The wire connection portion 42AA is disposed in the recess 52A of the second die pad 50. In a plan view, the shape of the wire connection portion 42AA is a substantially rectangular shape with the Y direction as the longitudinal direction and the X direction as the lateral direction. In a plan view, the wire connection portion 42AA extends in the Y direction. In a plan view, a portion of the wire connection portion 42AA closer to the lead connection portion 42AB is tapered such that the width dimension (size in the Y direction) of the wire connection portion 42AA decreases toward the lead connection portion 42AB. A corner portion of the wire connection portion 42AA closer to the bottom surface 52AB of the recess 52A and closer to the second inner lead portion 43A includes a curved surface 42AE.

[0482] The lead connection portion 42AB is disposed closer to the second sealing side surface 94 than the recess 52A of the second die pad 50. In a plan view, the lead connection portion 42AB extends in the X direction. In one example, the size of the lead connection portion 42AB in the Y direction is smaller than the size of the wire connection portion 42AA in the Y direction.

[0483] The second inner lead portion 43A has a substantially T-shape in plan view. The second inner lead portion 43A includes a wire connection portion 43AA and a lead connection portion 43AB extending from the wire connection portion 43AA toward the second sealing side surface 94. The lead connection portion 43AB is connected to the second outer lead portion 43B.

[0484] The wire connection portion 43AA is disposed in the recess 52A of the second die pad 50. In a plan view, the wire connection portion 43AA has a generally rectangular shape with the Y direction as its longitudinal direction and the X direction as its lateral direction. In a plan view, the wire connection portion 43AA extends in the Y direction. In a plan view, a portion of the wire connection portion 43AA closer to the lead connection portion 43AB is tapered such that the width dimension (size in the Y direction) of the wire connection portion 43AA decreases toward the lead connection portion 43AB. A corner portion of the wire connection portion 43AA closer to the bottom surface 52AB of the recess 52A and closer to the second inner lead portion 44A includes a curved surface 43AE.

[0485] The lead connection portion 43AB is disposed closer to the second sealing side surface 94 than the recess 52A of the second die pad 50. In a plan view, the lead connection portion 43AB extends in the X direction. In one example, the size of the lead connection portion 43AB in the Y direction is smaller than the size of the wire connection portion 43AA in the Y direction.

[0486] The second inner lead portion 44A has a substantially L-shaped shape in a plan view. The second inner lead portion 44A includes a wire connection portion 44AA and a lead connection portion 44AB extending from the wire connection portion 44AA toward the second sealing side surface 94. The lead connection portion 44AB is connected to the second outer lead portion 44B.

[0487] The wire connection portion 44AA is disposed in the recess 52A of the second die pad 50. In a plan view, the shape of the wire connection portion 44AA is a substantially rectangular shape with the Y direction as the longitudinal direction and the X direction as the lateral direction. In a plan view, the wire connection portion 44AA can be said to extend in the Y direction from the lead connection portion 44AB. The wire connection portion 44AA extends from the lead connection portion 44AB toward the second inner lead portion 43A. A corner portion of the wire connection portion 44AA near the bottom surface 52AB of the recess 52A and near the suspension lead portion 52D includes a curved surface 44AE.

[0488] The lead connection portion 44AB is disposed closer to the second sealing side surface 94 than the recess 52A of the second die pad 50. In a plan view, the lead connection portion 44AB extends in the X direction. In one example, the size of the lead connection portion 44AB in the Y direction is smaller than the size of the wire connection portion 44AA in the Y direction.

[0489] In this way, the lead connection portions 42AB to 44AB correspond to the "third portion of the second lead terminal," and the wire connection portions 42AA to 44AA correspond to the "fourth portion of the second lead terminal." The X direction in which the lead connection portions 42AB to 44AB extend corresponds to the "first direction," and the Y direction in which the wire connection portions 42AA to 44AA extend corresponds to the "second direction." In the ninth embodiment, the wire connection portions 42AA to 44AA extend in a direction perpendicular to the direction in which the lead connection portions 42AB to 44AB extend in a plan view, but this is not limited thereto. It is sufficient that the wire connection portions 42AA to 44AA extend in a direction intersecting the direction in which the lead connection portions 42AB to 44AB extend in a plan view.

[0490] The cross-sectional structures of the wire bonding portions 11AA to 13AA and 42AA to 44AA are the same as those in the first embodiment. The first chip 60 has a plurality of first electrode pads 67 (three in the ninth embodiment), a plurality of second electrode pads 68 (three in the ninth embodiment), and one third electrode pad 69. Each of the first electrode pads 67, each of the second electrode pads 68, and the third electrode pad 69 is provided so as to be exposed from the chip surface 61.

[0491] Each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 may contain at least one of titanium, titanium nitride, copper, aluminum, and tungsten. In one example, each of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 has a laminated structure of titanium and copper. Note that the material constituting one or two of the first electrode pads 67, second electrode pads 68, and third electrode pads 69 may be different from the material constituting the remaining electrode pads.

[0492] The multiple first electrode pads 67 are provided in a position closer to the second chip side surface 64 than the center in the X direction of the chip surface 61 in a plan view. The multiple first electrode pads 67 are provided in a position closer to the third chip side surface 65 of the chip surface 61 in a plan view. In other words, the distance in the Y direction between the first electrode pad 67 closest to the third chip side surface 65 and the third chip side surface 65 in a plan view is smaller than the distance in the Y direction between the first electrode pad 67 closest to the fourth chip side surface 66 and the fourth chip side surface 66.

[0493] The second electrode pads 68 are electrode pads that are individually and electrically connected to the first lead terminals 11 to 13. The second electrode pads 68 are provided at positions closer to the fourth chip side surface 66 than the center of the chip surface 61 in the Y direction in a plan view.

[0494] The third electrode pad 69 is provided on the chip surface 61 closer to the third chip side surface 65 in the Y direction than the plurality of second electrode pads 68 in a plan view. The third electrode pad 69 is provided on the chip surface 61 closer to the first chip side surface 63 in the X direction than the plurality of first electrode pads 67 in a plan view.

[0495] The second chip 70 has a plurality of (three in the ninth embodiment) first electrode pads 77, a plurality of (three in the ninth embodiment) second electrode pads 78, and one third electrode pad 79. Each of the first electrode pads 77, each of the second electrode pads 78, and the third electrode pad 79 is provided so as to be exposed from the chip surface 71.

[0496] Each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 may contain at least one of titanium, titanium nitride, copper, aluminum, and tungsten. In one example, each of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 has a laminated structure of titanium and copper. Note that the material constituting one or two of the first electrode pads 77, second electrode pads 78, and third electrode pads 79 may be different from the material constituting the remaining electrode pads.

[0497] The multiple first electrode pads 77 are provided in a position closer to the second chip side surface 74 than the center in the X direction of the chip surface 71 in a plan view. The multiple first electrode pads 77 are provided in a position closer to the fourth chip side surface 76 on the chip surface 71 in a plan view. That is, the distance in the Y direction between the first electrode pad 77 closest to the fourth chip side surface 76 in a plan view and the fourth chip side surface 76 is smaller than the distance in the Y direction between the first electrode pad 77 closest to the third chip side surface 75 and the third chip side surface 75.

[0498] The multiple second electrode pads 78 are provided at positions closer to the first chip side surface 73 than the center in the X direction of the chip surface 71 in a plan view. The third electrode pad 79 is provided closer to the third sealing side surface 95 than the center in the Y direction of the chip surface 71 in a plan view. The third electrode pad 79 is provided closer to the third sealing side surface 95 than the multiple first electrode pads 77 in a plan view. The third electrode pad 79 is provided closer to the third sealing side surface 95 than the multiple second electrode pads 78 in a plan view.

[0499] Next, a description will be given of the electrical connection configuration between the first chip 60 and the second chip 70. As shown in Fig. 44, the plurality of first electrode pads 67 of the first chip 60 and the plurality of first electrode pads 77 of the second chip 70 are individually connected by a plurality of inter-chip wires WA (three in the ninth embodiment). This allows the plurality of first electrode pads 67 and the plurality of first electrode pads 77 to be individually electrically connected.

[0500] In one example, the distance between two adjacent first electrode pads 67 in the Y direction among the three first electrode pads 67 on the first chip 60 is greater than the distance between two adjacent first electrode pads 77 in the Y direction among the three first electrode pads 77 on the second chip 70. Therefore, the distance between two adjacent inter-chip wires WA in the Y direction among the three inter-chip wires WA closer to the third sealing side surface 95 gradually increases from the first electrode pad 67 toward the first electrode pad 77.

[0501] Here, the three inter-chip wires WA are referred to as inter-chip wires WA1, WA2, and WA3 in order from the third sealing side surface 95 to the fourth sealing side surface 96. In a plan view, the inter-chip wire WA1 is inclined from the third sealing side surface 95 to the fourth sealing side surface 96 as it moves from the first electrode pad 67 to the first electrode pad 77. In a plan view, the inter-chip wire WA2 extends along the X direction between the first electrode pad 67 and the first electrode pad 77. In a plan view, the inter-chip wire WA3 is inclined from the fourth sealing side surface 96 to the third sealing side surface 95 as it moves from the first electrode pad 67 to the first electrode pad 77.

[0502] In a plan view, the acute angle formed between the inter-chip wire WA1 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA1 and the X direction is greater than 7° and less than or equal to 10°.

[0503] In a plan view, the acute angle formed by the inter-chip wires WA1 and WA2 is 10° or less. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed by the inter-chip wires WA1 and WA2 is greater than 7° and less than or equal to 10°.

[0504] In a plan view, the acute angle formed between the inter-chip wire WA3 and the X direction is 10° or less. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wire WA3 and the X direction is greater than 7° and less than or equal to 10°.

[0505] In a plan view, the acute angle formed between the inter-chip wires WA3 and WA2 is 10° or less. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wires WA3 and WA2 is greater than 7° and less than or equal to 10°.

[0506] In a plan view, the acute angle formed between the inter-chip wires WA1 and WA3 is 10° or less. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 0° and less than or equal to 3°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 3° and less than or equal to 5°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 5° and less than or equal to 7°. In one example, the acute angle formed between the inter-chip wires WA1 and WA3 is greater than 7° and less than or equal to 10°.

[0507] 45 , the second electrode pads 68 of the first chip 60 and the first lead terminals 11 to 13 are individually connected by a plurality of first lead wires WB (three in the ninth embodiment). This electrically connects the first chip 60 to the first lead terminals 11 to 13 individually. Each of the first lead terminals 11 to 13 is individually connected to the second electrode pads 68 by a single first lea...

Claims

1. A first chip including an isolation transformer, A second chip that performs at least one of signal transmission and reception with the first chip, A first die pad on which the first chip is mounted, A second die pad that is disposed at a distance from the first die pad in a first direction and on which the second chip is mounted, A plurality of first lead terminals that are disposed on the opposite side of the second die pad with respect to the first die pad in the first direction and are arranged in a second direction orthogonal to the first direction in a plan view, A plurality of second lead terminals that are disposed on the opposite side of the first die pad with respect to the second die pad in the first direction and are arranged in the second direction, An inter-chip wire connecting the first chip and the second chip, A first lead wire that individually connects the first chip and the plurality of first lead terminals, and includes: Among the plurality of first lead terminals, the first lead terminals disposed at both ends in the second direction are connected to both ends in the second direction of the first die pad, Among the plurality of second lead terminals, the second lead terminals disposed at both ends in the second direction are connected to both ends in the second direction of the second die pad, The inter-chip wire is formed of a material containing gold, The first lead wire is formed of a material containing copper or aluminum A signal transmission device.

2. The first lead wire has a structure in which palladium is coated on the surface of a copper wire The signal transmission device according to Claim 1.

3. The signal transmission device according to Claim 1, further comprising a plurality of second lead wires that individually connect the second chip and the plurality of second lead terminals, The second lead wire is formed of a material containing copper or aluminum The signal transmission device according to Claim 1.

4. The signal transmission device according to Claim 1, further comprising a first die pad wire that connects the first chip and the first die pad, The first die pad wire is formed of a material containing copper or aluminum The signal transmission device according to Claim 1.

5. The signal transmission device according to Claim 1, further comprising a second die pad wire that connects the second chip and the second die pad, The second die pad wire is formed of a material containing copper or aluminum The signal transmission device according to Claim 1.

6. The first die pad wire is a bonding wire A security bond is formed at the joint of the first die pad wire with the first die pad. The signal transmission device according to claim 4. **Claim 7** The second die pad wire is a bonding wire, A security bond is formed at the joint of the second die pad wire with the second die pad. The signal transmission device according to claim 5. **Claim 8** The plurality of first lead terminals A first portion extending in the first direction, A second portion that is continuously provided to the first portion and extends in a direction intersecting the first direction with respect to the first portion, Including, The second portion includes a side surface that intersects the first lead wire connected to the second portion in a plan view, The side surface faces the first die pad in a plan view. The signal transmission device according to claim 1. **Claim 9** The plurality of inter-chip wires are formed to be parallel to each other in a plan view. The signal transmission device according to claim 1. **Claim 10** Further comprising a rectangular flat sealing resin that seals the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad, and partially seals each of the first lead terminals and the second lead terminals, The plurality of first lead terminals A first connection terminal integrated with the first die pad, A first spaced terminal disposed apart from the first die pad, Including, The first spaced terminal has a through hole penetrating in the thickness direction of the first spaced terminal, The through hole is filled with the sealing resin. The signal transmission device according to claim 1. **Claim 11** Further comprising a rectangular flat sealing resin that seals the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad, and partially seals each of the first lead terminals and the second lead terminals, Each of the first lead terminals A first outer lead portion exposed outside the sealing resin, A first inner lead portion provided inside the sealing resin and connected to the first outer lead portion, Including, The plurality of first lead terminals A first specific terminal having a through hole formed in the thickness direction of the first lead terminal in the first inner lead portion, A second specific terminal having no through hole formed in the first inner lead portion, Including, The plurality of first lead wires a first specific wire joined to the first specific terminal; a second specific wire joined to the second specific terminal; comprising a security bond is formed at a joint portion of the second specific wire joined to the second specific terminal The signal transmission device according to claim 1.

12. further comprising a rectangular flat sealing resin that seals the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad and partially seals each of the first lead terminals and each of the second lead terminals, the sealing resin has a sealing surface, a sealing back surface opposite to the sealing surface, and a sealing side surface connecting the sealing surface and the sealing back surface, the sealing side surface a first sealing side surface where the plurality of first lead terminals are exposed; a second sealing side surface where the plurality of second lead terminals are exposed; a third sealing side surface and a fourth sealing side surface connecting the first sealing side surface and the second sealing side surface; comprising both the third sealing side surface and the fourth sealing side surface are composed only of the sealing resin without exposing the conductive member The signal transmission device according to claim 1.

13. The first chip an element insulating layer; a first resin layer provided on the element insulating layer; a second resin layer provided on the first resin layer; comprising the insulating transformer a surface-side coil disposed on the first resin layer and covered by the second resin layer; a back-side coil disposed opposite to the surface-side coil in the thickness direction of the element insulating layer and embedded in the element insulating layer The signal transmission device according to claim 1.

14. further comprising a rectangular flat sealing resin that seals the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad and partially seals each of the first lead terminals and each of the second lead terminals, The first chip an element insulating layer; a passivation film formed on the element insulating layer so as to cover the element insulating layer; a low dielectric layer formed on the surface of the passivation film and having a lower relative permittivity than the passivation film; the sealing resin covers the low dielectric layer The signal transmission device according to claim 1.

15. The insulating transformer a surface-side coil disposed closer to the chip surface of the first chip; a back-side coil disposed opposite to the surface-side coil; comprising The surface-side coil has a coil surface, a coil back surface on the side opposite to the coil surface, and a coil side surface connecting the coil surface and the coil back surface, and a curved surface is formed between the coil surface and the coil side surface. The signal transmission device according to claim 1. **Claim 16** The first chip includes a flat substrate mounted on the first die pad, and an element insulating layer formed on the substrate and provided with at least a part of the insulating transformer. The substrate has a substrate back surface facing the first die pad, a substrate front surface on the side opposite to the substrate back surface, a substrate side surface connecting the substrate back surface and the substrate front surface, a first portion including the substrate back surface, a second portion provided on the first portion and including the substrate front surface, and a stepped portion formed such that the second portion is located inside the substrate with respect to the first portion. The signal transmission device according to claim 1. **Claim 17** The first die pad has a first tip surface facing the second die pad in a plan view in the first direction, a first base surface on the side opposite to the first tip surface in a plan view, a first side surface and a second side surface constituting both side surfaces in the second direction, a first tip-side curved surface formed between the first tip surface and the first side surface, a second tip-side curved surface formed between the first tip surface and the second side surface, a first base-side curved surface formed between the first base surface and the first side surface, and a second base-side curved surface formed between the first base surface and the second side surface. In a plan view, the arc lengths of both the first tip-side curved surface and the second tip-side curved surface are longer than the arc lengths of both the first base-side curved surface and the second base-side curved surface. The signal transmission device according to claim 1. **Claim 18** The signal transmission device further includes a rectangular flat sealing resin that seals the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad and partially seals each of the first lead terminals and the second lead terminals. The first lead terminal includes a first inner lead portion provided in the sealing resin. The first inner lead portion includes a wire connection portion to which the first lead wire is connected. The wire connection portion has an inner lead surface to which the first lead wire is joined, and an inner lead back surface facing the side opposite to the inner lead surface. An inner lead side surface connecting the inner lead front surface and the inner lead back surface, having, the inner lead side surface includes a front end surface facing the first die pad in the first direction, a plating layer is formed on the inner lead front surface, no plating layer is formed at an end portion of the inner lead front surface on the front end surface side, and it is in contact with the encapsulation resin The signal transmission device according to claim 1.

19. further comprising a rectangular flat encapsulation resin that encapsulates the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad and partially encapsulates each of the first lead terminals and each of the second lead terminals, the plurality of first lead terminals include a first outer lead portion protruding outside the encapsulation resin, the first outer lead portion, an outer lead front surface, an outer lead back surface facing the side opposite to the outer lead front surface, an outer lead side surface connecting the outer lead front surface and the outer lead back surface at both ends in the width direction of the first outer lead portion, an outer lead end surface which is an end surface in the direction in which the first outer lead portion extends, having, a plating layer is formed on the outer lead front surface, the outer lead back surface, and the outer lead side surface, the plating layer is continuously formed from the outer lead back surface toward the outer lead front surface among the outer lead end surfaces and is separated from the outer lead front surface The signal transmission device according to claim 1.

20. further comprising a rectangular plate-shaped encapsulation resin that encapsulates the first chip, the second chip, the inter-chip wire, the first lead wire, the first die pad, and the second die pad and partially encapsulates each of the first lead terminals and each of the second lead terminals, the outer surface of the encapsulation resin is formed such that the surface roughness Rz is 8 μm or more The signal transmission device according to claim 1.