Signal transmission device

Abstract

This signal transmission device comprises a first chip that includes a first transistor, a second chip, a plurality of first lead terminals, a plurality of second lead terminals, an inter-chip wire that electrically connects the first chip and the second chip, and a plurality of first lead wires that separately connect the first chip and the plurality of first lead terminals. The inter-chip wire is formed using a material that contains gold. The first lead wires are formed using a material that contains 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 signal transmission device according to one aspect of the present disclosure includes a first chip including an isolation transformer, a second chip that receives signals from the first chip and / or transmits signals to the first chip, a third chip that receives signals from the first chip and / or transmits signals to the first chip, a first die pad on which the first chip is mounted, a second die pad that is disposed apart from the first die pad in a first direction and on which the second chip is mounted, a third die pad that is disposed apart from the first die pad in the first direction and is disposed apart from the second die pad in a second direction orthogonal to the first direction in a plan view and on which the third chip is mounted, and a third die pad that is disposed apart from the first die pad in the first direction and apart from the second die pad in a second direction orthogonal to the first direction in a plan view and on which the third chip is mounted, and The semiconductor device comprises: a plurality of first lead terminals arranged on the opposite side of the first die pad from the second die pad and the third die pad in the first direction and arranged in the second direction in a planar view; a plurality of second lead terminals arranged on the opposite side of the first die pad from the second die pad and the third die pad in the first direction and arranged in the second direction; inter-chip wires individually connecting the first chip to the second chip and the third chip; and a plurality of first lead wires individually connecting the first chip to the plurality of first lead terminals, wherein the inter-chip wires are formed of a material containing gold, and the first lead wires are 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 a first frame and its periphery of FIG. 7. FIG. 9 is an enlarged view of a portion of the first frame and its periphery of FIG. 8. FIG. 10 is an enlarged view of a remaining portion of the first frame and its periphery of FIG. 8. FIG. 11 is a schematic cross-sectional view of a wire connection portion of a first lead terminal. FIG. 12 is an enlarged view of a second die pad and its periphery of FIG. 7. FIG. 13 is an enlarged view of a third die pad and its periphery of FIG. 7. FIG. 14 is a schematic cross-sectional view of a wire connection portion of a second lead terminal. FIG. 15 is an enlarged perspective view of a second bond portion of a wire for a third die pad and its periphery. FIG. 16 is a circuit diagram of a signal transmission device according to the first embodiment. FIG. 17 is a schematic plan view showing an example of the internal structure of a first chip in the signal transmission device according to the first embodiment. FIG. 18 is an enlarged plan view of the transformer region of FIG. 17. FIG. 19 is a schematic plan view showing an example of the internal structure of the first chip at a position different from that of FIG. 18 in the thickness direction of the first chip. FIG. 20 is an enlarged plan view of the transformer region of FIG. 19. FIG. 21 is a cross-sectional view showing the cross-sectional structure of a first transformer of the first chip and its periphery. FIG. 22 is an enlarged view of a portion of the first chip of FIG. 21. FIG. 23 is an enlarged view of the conductor of a first front-side coil in the first chip of FIG. 22. FIG. 24 is an enlarged view of the conductor of a first back-side coil in the first chip of FIG. 22. FIG. 25 is a cross-sectional view showing the cross-sectional structure of a portion of the circuit region of the first chip. FIG. 26 is an enlarged view of a first via and its periphery in FIG. 25. 27 and 28 are enlarged plan views of a part of the first frame and its periphery in the signal transmission device of the second embodiment, respectively, and are enlarged plan views of a second die pad and its periphery in the signal transmission device of the second embodiment.FIG. 29 is an enlarged plan view of the third die pad and its periphery in the signal transmission device of the second embodiment. FIG. 30 is an enlarged plan view of a portion of the first frame and its periphery in the signal transmission device of the third embodiment. FIG. 31 is an enlarged plan view of a remaining portion of the first frame and its periphery in the signal transmission device of the third embodiment. FIG. 32 is an enlarged plan view of the second die pad and its periphery in the signal transmission device of the third embodiment. FIG. 33 is an enlarged plan view of the third die pad and its periphery in the signal transmission device of the third embodiment. FIG. 34 is an enlarged plan view of a portion of the first frame and its periphery in the signal transmission device of the fourth embodiment. FIG. 35 is an enlarged plan view of a remaining portion of the first frame and its periphery in the signal transmission device of the fourth embodiment. FIG. 36 is an enlarged plan view of the second die pad and its periphery in the signal transmission device of the fourth embodiment. FIG. 37 is an enlarged plan view of the third die pad and its periphery in the signal transmission device of the fourth embodiment. FIG. 38 is an enlarged plan view of a portion of the first die pad, the third die pad, and their periphery in the signal transmission device of the fifth embodiment. FIG. 39 is a schematic cross-sectional view of the first chip and the first die pad in the signal transmission device of the sixth embodiment. FIG. 40 is a schematic cross-sectional view of the first chip and the first die pad cut in a direction different from that of FIG. 39 . FIG. 41 is a schematic cross-sectional view of the second chip and the second die pad. FIG. 42 is a schematic cross-sectional view of the second chip and the second die pad cut in a direction different from that of FIG. 41 . FIG. 43 is a schematic cross-sectional view of the third chip and the third die pad. FIG. 44 is a schematic cross-sectional view of the third chip and the third die pad cut in a direction different from that of FIG. 43 . FIG. 45 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the sixth embodiment. FIG. 46 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to that of FIG. 45 . FIG. 47 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to that of FIG. 46 . Fig. 48 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device following Fig. 47. Fig. 49 is a plan view schematically showing the internal structure of the signal transmission device according to the seventh embodiment.FIG. 50 is a plan view schematically showing the internal structure of the signal transmission device of the eighth embodiment. FIG. 51 is a plan view enlarging the first frame and its periphery of the signal transmission device of the ninth embodiment. FIG. 52 is a plan view enlarging the first die pad and its periphery of the signal transmission device of the ninth embodiment. FIG. 53 is a cross-sectional view schematically showing an example of the cross-sectional structure of the first transformer of the first chip and its periphery of the signal transmission device of the tenth embodiment. FIG. 54 is a cross-sectional view enlarging a portion of the first transformer of FIG. 53 and its periphery. FIG. 55 is a cross-sectional view schematically showing an example of a manufacturing process of the signal transmission device of the tenth embodiment. FIG. 56 is a cross-sectional view schematically showing an example of a manufacturing process of the signal transmission device subsequent to FIG. 55. FIG. 57 is a cross-sectional view schematically showing an example of a manufacturing process of the signal transmission device subsequent to FIG. 56. FIG. 58 is a cross-sectional view showing the cross-sectional structure of the first transformer of the first chip and a portion of its periphery of the signal transmission device of the eleventh embodiment. FIG. 59 is an enlarged cross-sectional view of a portion of the first surface side coil and its periphery in the first transformer of the first chip for the signal transmission device of the twelfth embodiment. FIG. 60 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the twelfth embodiment. FIG. 61 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 60. FIG. 62 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 61. FIG. 63 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 62. FIG. 64 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 63. FIG. 65 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 64. FIG. 66 is an enlarged cross-sectional view of a portion of the first surface side coil and its periphery in the first transformer of the first chip for the signal transmission device of the thirteenth embodiment. FIG. 67 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device of the thirteenth embodiment. FIG. 68 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device subsequent to FIG. 67. Fig. 69 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device following Fig. 68. Fig. 70 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device following Fig. 69. Fig. 71 is a cross-sectional view schematically showing an example of a manufacturing process for the signal transmission device following Fig. 70.Fig. 72 is a schematic plan view showing an example of the internal structure of the first chip in a signal transmission device of a modified example. Fig. 73 is a schematic plan view showing an example of the internal structure of the first chip at a position different from that in Fig. 72 in the thickness direction of the first chip. Fig. 74 is a plan view showing a schematic internal structure of a signal transmission device of a modified example. Fig. 75 is a plan view showing a schematic 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 26. Figures 1 to 6 show the external structure of the signal transmission device 10. Figures 7 to 15 show the internal structure of the signal transmission device 10. Figure 16 shows the circuit configuration of the signal transmission device 10. Figures 17 to 26 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 X direction as the short side direction and the Y direction as the long side direction. In plan view, the size of the sealing resin 90 in the Y direction is at least twice the size of the sealing resin 90 in the X direction. In plan view, the size of the sealing resin 90 in the Y direction is no more than three times the size of the sealing resin 90 in the X direction. In one example, in plan view, the size of the sealing resin 90 in the Y direction is about 2.5 times the size of the sealing resin 90 in the X direction. In one example, the dimension of the sealing resin 90 in the X direction is about 4.0 mm, the dimension of the sealing resin 90 in the Y direction is about 10.0 mm, and the dimension (thickness) of the sealing resin 90 in the Z direction is about 1.75 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 toward 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 longitudinal 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 toward 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 longitudinal 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 0.41 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 1.27 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 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 mold are rounded and curved. In other words, the corners are R-chamfered. When the mold having such corners moves in the +Z direction so as to cut both the first lead frame and the second lead frame, the plating layer 26 on the back surface 22A of the outer lead is pulled toward the front surface 21A of the outer lead, thereby forming an end surface plating layer 27 on the end surface 24A of the outer lead.

[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 to 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 and a third chip 80 mounted on second frame 10B. Sealing resin 90 seals first chip 60, second chip 70, and third chip 80, 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] Of the first lead terminals 11 to 18, the first lead terminal 14 that is arranged near the center in the Y direction is connected to the first die pad 30. In one example, the first lead terminal 14 and the first die pad 30 are integrated. The first lead terminals 11 to 13 and 15 to 18 are arranged spaced apart from the first die pad 30. As shown in FIG. 7 , the first lead terminals 11 to 18 can be said to be arranged spaced apart from each other in the Y 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 chip 60 mounted on the first die pad 30 is formed in a flat plate shape. In a plan view, the shape of the first chip 60 is a rectangle 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 by a first conductive bonding material SD1. More specifically, the first chip 60 is die-bonded to the first die pad 30.

[0054] 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 50A and a third die pad 50B. The second lead terminals 41 to 48, the second die pad 50A, and the third die pad 50B 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, the second die pad 50A, and the third die pad 50B are formed of the same metal material as the first lead terminals 11 to 18 and the first die pad 30.

[0055] Of the second lead terminals 41 to 48, the second lead terminal 41 located at the end closer to the third sealing side surface 95 is connected to the second die pad 50A. In one example, the second lead terminal 41 and the second die pad 50A are integrated. Of the second lead terminals 41 to 48, the second lead terminal 46 located closer to the fourth sealing side surface 96 is connected to the third die pad 50B. In one example, the second lead terminal 46 and the third die pad 50B are integrated. The second lead terminals 42 to 45 arranged between the second lead terminal 41 and the second lead terminal 46 in the Y direction are arranged spaced apart from the second die pad 50A and the third die pad 50B. The second lead terminals 47 and 48 located closer to the fourth sealing side surface 96 than the second lead terminal 46 are arranged spaced apart from the third die pad 50B. As shown in FIG. 7 , the second lead terminals 41 to 48 can be said to be arranged spaced apart from each other in the Y direction.

[0056] Both the second die pad 50A and the third die pad 50B are 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 50A and the third die pad 50B. The first die pad 30, and the second die pad 50A and the third die pad 50B can also be considered to be arranged in the short-side direction of the sealing resin 90. Both the second die pad 50A and the third die pad 50B are disposed closer to the second sealing side surface 94 than the center of the sealing resin 90 in the X direction. Both the second die pad 50A and the third die pad 50B are disposed opposite the first die pad 30 in the X direction. In other words, the first die pad 30 has a size in the Y direction that allows it to face the second die pad 50A and the third die pad 50B. Here, the X direction corresponds to the "first direction."

[0057] In a plan view, the second die pad 50A and the third die pad 50B are arranged on the opposite side of the first die pad 30 in the X direction from the side on which the first lead terminals 11 to 18 are arranged. In other words, in a plan view, the first lead terminals 11 to 18 are arranged on the opposite side of the first die pad 30 in the X direction from the second die pad 50A and the third die pad 50B. In addition, in a plan view, the second lead terminals 41 to 48 are arranged on the opposite side of the second die pad 50A and the third die pad 50B from the first die pad 30.

[0058] The second die pad 50A and the third die pad 50B are arranged spaced apart from each other in the Y direction. That is, in the first embodiment, the Y direction can be said to be the arrangement direction of the second die pad 50A and the third die pad 50B. The second die pad 50A is arranged closer to the third sealing side surface 95 than the third die pad 50B. The second die pad 50A is arranged closer to the third sealing side surface 95 than the center of the sealing resin 90 in the Y direction. The third die pad 50B is arranged closer to the fourth sealing side surface 96 than the center of the sealing resin 90 in the Y direction. Here, the Y direction corresponds to the "second direction."

[0059] The second chip 70 mounted on the second die pad 50A 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 size of the second chip 70 in the X direction is smaller than the size of the first chip 60 in the X direction. The size of the second chip 70 in the Y direction is smaller than the size of the first chip 60 in the Y direction. The second chip 70 is mounted on the second die pad 50A with a second conductive bonding material SD2. More specifically, the second chip 70 is die-bonded to the second die pad 50A.

[0060] The third chip 80 mounted on the third die pad 50B is formed in a flat plate shape. In plan view, the third chip 80 has a rectangular shape with its short side in the X direction and its long side in the Y direction. The size of the third chip 80 in the X direction is smaller than the size of the first chip 60 in the X direction. The size of the third chip 80 in the Y direction is smaller than the size of the first chip 60 in the Y direction. In one example, the sizes of the third chip 80 in the X and Y directions are the same as the sizes of the second chip 70 in the X and Y directions. The third chip 80 is mounted on the third die pad 50B with a third conductive bonding material SD3. More specifically, the third chip 80 is die-bonded to the third die pad 50B. The first to third conductive bonding materials SD1 to SD3 may be, for example, solder paste or silver paste.

[0061] The second chip 70 is disposed closer to the third die pad 50B of the second die pad 50A. When viewed from the X direction, the second chip 70 is disposed closer to the third sealing side surface 95 than the first chip 60. The third chip 80 is disposed closer to the fourth sealing side surface 96 than the first chip 60.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The detailed planar structure of the first die pad 30 will be described. As shown in FIG. 8 , the first die pad 30 is formed in a generally T-shape in 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 the end surface closest to the second sealing side surface 94 (see FIG. 7 ) among both end surfaces of the first die pad 30 in the X direction, and the first base surface 32 is the end surface closest to the first sealing side surface 93 among both end surfaces of the first die pad 30 in the X direction. The first side surface 33 is the end surface closest to the third sealing side surface 95 (see FIG. 7 ) among both end surfaces of the first die pad 30 in the Y direction, and the second side surface 34 is the end surface closest to the fourth sealing side surface 96 (see FIG. 7 ) among both end surfaces of the first die pad 30 in the Y direction. The first tip surface 31 is a surface that faces both the second die pad 50A and the third die pad 50B (see FIG. 7 ) in the X direction and extends along the Y direction in plan view. The length of the first tip surface 31 in the Y direction is longer than the length of the first base end surface 32 in the Y direction. Both the first side surface 33 and the second side surface 34 are surfaces that extend along the X direction in plan view.

[0066] The first die pad 30 further has a first tip side curved surface 35A and a second tip side curved surface 35B. The first tip side curved surface 35A is formed between the first tip side surface 31 and the first side surface 33. The first tip side curved surface 35A has a shape in which the portion between the first tip side surface 31 and the first side surface 33 is R-chamfered. The second tip side curved surface 35B is formed between the first tip side surface 31 and the second side surface 34. The second tip side curved surface 35B has a shape in which the portion between the first tip side surface 31 and the second side surface 34 is R-chamfered. In one example, in a plan view, the arc length of the first tip side curved surface 35A and the arc length of the second tip side curved surface 35B are equal to each other. In one example, it can also be said that the curvature radius of the first tip side curved surface 35A and the curvature radius of the second tip side curved surface 35B are equal to each other in a plan view.

[0067] The first die pad 30 further has a first recess 36A into which the first lead terminals 11 to 13 fit, a second recess 36B into which the first lead terminals 17 and 18 fit, and a third recess 36C into which the first lead terminals 15 and 16 fit.

[0068] The first recessed portion 36A is formed in a portion of the first die pad 30 closer to the fourth sealing side surface 96. The first recessed portion 36A is formed to be recessed in the X direction from the second side surface 34 toward the first side surface 33. The first recessed portion 36A is formed closer to the first sealing side surface 93 than the first tip surface 31 in the X direction. Meanwhile, the first recessed portion 36A is formed so as to remove the first base end surface 32. That is, the first recessed portion 36A opens toward both the first sealing side surface 93 and the fourth sealing side surface 96. A first tip protrusion 38A is provided in a portion of the first die pad 30 between the first recessed portion 36A and the first tip surface 31 in the X direction. In a plan view, the first tip protrusion 38A extends in the Y direction. The first tip protrusion 38A includes the second side surface 34, the first tip surface 31, and the second tip curved surface 35B. The first tip-side protrusion 38A faces the third die pad 50B (see FIG. 7) in the X direction.

[0069] The first recessed portion 36A includes a first surface 36A1 extending in the X direction, a second surface 36A2 extending in the Y direction, and a curved recess 36A3 formed between the first surface 36A1 and the second surface 36A2. The first surface 36A1 is positioned closer to the first side surface 33 than the second side surface 34 and is connected to the first base end surface 32. The second surface 36A2 forms a part of the side surface of the first tip-side protrusion 38A. In a plan view, the curved recess 36A3 is formed as an arc portion connecting the first surface 36A1 and the second surface 36A2. In one example, in a plan view, the arc length of the curved recess 36A3 is greater than the arc length of the second tip-side curved surface 35B. In a plan view, the radius of curvature of the curved recess 36A3 can be said to be greater than the radius of curvature of the second tip-side curved surface 35B.

[0070] The second recessed portion 36B is formed in a portion of the first die pad 30 closer to the third sealing side surface 95. The second recessed portion 36B is formed to be recessed in the X direction from the first side surface 33 toward the second side surface 34. The second recessed portion 36B is formed closer to the first sealing side surface 93 than the first tip surface 31 in the X direction. On the other hand, the second recessed portion 36B is formed so as to remove the first base end surface 32. In other words, the second recessed portion 36B is open toward both the first sealing side surface 93 and the third sealing side surface 95. A second tip protrusion 38B is provided in a portion of the first die pad 30 between the second recessed portion 36B and the first tip surface 31 in the X direction. In a plan view, the second tip protrusion 38B extends in the Y direction. The second tip protrusion 38B includes the first side surface 33, the first tip surface 31, and the first tip curved surface 35A. The second tip side protrusion 38B faces the second die pad 50A (see FIG. 7) in the X direction.

[0071] The second recessed portion 36B includes a first surface 36B1 extending in the X direction, a second surface 36B2 extending in the Y direction, and a curved recessed portion 36B3 formed between the first surface 36B1 and the second surface 36B2. The first surface 36B1 is positioned closer to the second side surface 34 than the first side surface 33. The length of the first surface 36B1 is shorter than the length of the first surface 36A1 of the first recessed portion 36A. The second surface 36B2 forms a part of the side surface of the second tip-side protrusion 38B. The length of the second surface 36B2 is shorter than the length of the second surface 36A2 of the first recessed portion 36A. In a plan view, the curved recessed portion 36B3 is formed as an arc portion connecting the first surface 36B1 and the second surface 36B2. In one example, in a plan view, the arc length of the curved recessed portion 36B3 is greater than the arc length of the first tip-side curved surface 35A. In a plan view, the radius of curvature of the curved recess 36B3 is greater than the radius of curvature of the first distal curved surface 35A. In one example, in a plan view, the arc length of the curved recess 36B3 is equal to the arc length of the curved recess 36A3 of the first recess 36A. In a plan view, the radius of curvature of the curved recess 36B3 is equal to the radius of curvature of the curved recess 36A3.

[0072] The third recessed portion 36C is formed between the first recessed portion 36A and the second recessed portion 36B in the Y direction. The third recessed portion 36C is formed spaced apart from the first recessed portion 36A but is continuous with the second recessed portion 36B. The third recessed portion 36C is formed spaced apart from the first tip surface 31 in the X direction. On the other hand, the third recessed portion 36C is formed so as to remove the first base end surface 32. The third recessed portion 36C opens toward both the first sealing side surface 93 and the third sealing side surface 95. The first recessed portion 36A and the third recessed portion 36C form a connection portion 39 to which the first lead terminal 14 of the first die pad 30 is connected. The connection portion 39 includes the first base end surface 32.

[0073] The third recessed portion 36C includes a first surface 36C1 extending in the X direction, a second surface 36C2 extending in the Y direction, and a curved recess 36C3 formed between the first surface 36C1 and the second surface 36C2. The first surface 36C1 constitutes a side surface of the connecting portion 39. The first surface 36C1 is formed in a position between the first surface 36A1 of the first recessed portion 36A and the first surface 36B1 of the second recessed portion 36B, closer to the first surface 36A1 in the Y direction. The first surface 36C1 is connected to the first base end surface 32. The length of the first surface 36C1 is shorter than the length of the first surface 36B1 of the second recessed portion 36B. The second surface 36C2 is formed in a position between the second surface 36B2 of the second recessed portion 36B and the first base end surface 32, closer to the first base end surface 32 in the X direction. The length of the second surface 36C2 is shorter than the length of the second surface 36B2 of the second recessed portion 36B. In a plan view, the curved recessed portion 36C3 is formed as an arc portion connecting the first surface 36C1 and the second surface 36C2. In one example, in a plan view, the arc length of the curved recessed portion 36C3 is equal to the arc length of the first distal curved surface 35A. In a plan view, it can be said that the radius of curvature of the curved recessed portion 36C3 is equal to the radius of curvature of the first distal curved surface 35A. Thus, in a plan view, the arc length of the curved recessed portion 36C3 is shorter than the arc lengths of the curved recessed portions 36A3 and 36B3 of the first recessed portion 36A and the second recessed portion 36B. In a plan view, it can be said that the radius of curvature of the curved recessed portion 36C3 is smaller than the radius of curvature of the curved recessed portions 36A3 and 36B3.

[0074] An inclined surface 37 is formed between the second recessed portion 36B and the third recessed portion 36C. In a plan view, the inclined surface 37 extends obliquely from the first surface 36C1 to the first surface 36B1 as it moves from the second surface 36C2 to the second surface 36B2. The inclined surface 37 connects the second surface 36C2 and the first surface 36B1.

[0075] The detailed configuration of each of the first lead terminals 11 to 18 will be described. As shown in Fig. 7, of the first lead terminals 11 to 18, the first lead terminals 11 to 13 are arranged closer to the fourth sealing side surface 96 than the first chip 60 when viewed from the X direction. The first lead terminals 16 to 18 are arranged closer to the third sealing side surface 95 than the first chip 60 when viewed from the X direction. The first lead terminals 14 and 15 are arranged in positions overlapping with the first chip 60 when viewed from the X direction.

[0076] 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 configuration of the first inner lead portions 11A to 18A will be described below.

[0077] 9 , each of the first inner lead portions 11A to 13A of the first lead terminals 11 to 13 includes a portion that fits into the first recessed portion 36A of the first die pad 30. The first lead terminal 11 is formed in an L-shape in plan view. The first lead terminal 11 includes a wire connection portion 11AA and a lead connection portion 11AB that extends from the wire connection portion 11AA toward the first sealing side surface 93.

[0078] The wire connection portion 11AA is recessed into the first recess 36A of the first die pad 30. The wire connection portion 11AA extends in the Y direction. The wire connection portion 11AA includes a recess 11AC.

[0079] The recessed portion 11AC is formed in a portion of the wire connection portion 11AA closer to the first lead terminal 12. The recessed portion 11AC is recessed from one of the ends of the wire connection portion 11AA in the X direction closer to the first sealing side surface 93 toward the second tip-side protrusion 38B of the first die pad 30. The recessed portion 11AC includes a first surface 11AC1 extending in the X direction, a second surface 11AC2 extending in the Y direction, and a curved recessed portion 11AC3 formed between the first surface 11AC1 and the second surface 11AC2. The first surface 11AC1 is positioned closer to the first lead terminal 12 than the lead connection portion 11AB. The second surface 11AC2 is positioned so as to overlap the first lead terminal 12 when viewed from the X direction. In a plan view, the curved recessed portion 11AC3 is formed as an arc portion connecting the first surface 11AC1 and the second surface 11AC2. In one example, in a plan view, the arc length of the curved recess 11AC3 is greater than the arc length of the first distal curved surface 35A. In a plan view, the radius of curvature of the curved recess 11AC3 can be said to be greater than the radius of curvature of the first distal curved surface 35A. A narrow portion 11AA1 of the wire connection portion 11AA, whose width is narrowed by the recess 11AC, extends along the Y direction. The width dimension (size in the X direction) of the narrow portion 11AA1 is smaller than the width dimension (size in the Y direction) of the lead connection portion 11AB.

[0080] A through hole 11AD is formed in the wire connection portion 11AA. The through hole 11AD is formed in a portion of the wire connection portion 11AA that is closer to the lead connection portion 11AB than the recessed portion 11AC. The through hole 11AD is filled with a sealing resin 90.

[0081] The wire connection portion 11AA has an inclined surface 11AE formed in a corner portion of the wire connection portion 11AA that is closer to the second sealing side surface 94 (see FIG. 7 ) and the fourth sealing side surface 96. In a plan view, the inclined surface 11AE is inclined so as to approach the fourth sealing side surface 96 as it moves from the second sealing side surface 94 toward the first sealing side surface 93.

[0082] The lead connection portion 11AB extends along the X direction. The lead connection portion 11AB is disposed closer to the fourth sealing side surface 96 than the first die pad 30. The lead connection portion 11AB is connected to the first outer lead portion 11B.

[0083] The first lead terminal 12 is formed in an L-shape in a plan view 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.

[0084] The wire connection portion 12AA is inserted into the recessed portion 11AC of the wire connection portion 11AA of the first lead terminal 11. The wire connection portion 12AA extends in the Y direction. The wire connection portion 12AA includes the recessed portion 12AC.

[0085] The recessed portion 12AC is formed in a portion of the wire connection portion 12AA closer to the first lead terminal 13. The recessed portion 12AC is recessed from one of the ends of the wire connection portion 12AA in the X direction closer to the first sealing side surface 93 toward the recessed portion 11AC of the wire connection portion 11AA of the first lead terminal 11. The recessed portion 12AC includes a first surface 12AC1 extending in the X direction, a second surface 12AC2 extending in the Y direction, and a curved recessed portion 12AC3 formed between the first surface 12AC1 and the second surface 12AC2. The first surface 12AC1 is positioned closer to the first lead terminal 13 than the lead connection portion 12AB. The second surface 12AC2 is positioned so as to overlap the first lead terminal 13 when viewed from the X direction. In a plan view, the curved recessed portion 12AC3 is formed as an arc portion connecting the first surface 12AC1 and the second surface 12AC2. In one example, in a plan view, the arc length of the curved recess 12AC3 is smaller than the arc length of the curved recess 11AC3 of the first lead terminal 11. In a plan view, the radius of curvature of the curved recess 12AC3 can be said to be smaller than the radius of curvature of the curved recess 11AC3. A narrow portion 12AA1 of the wire connection portion 12AA, whose width is narrowed by the recess 12AC, extends along the Y direction. The width dimension (size in the X direction) of the narrow portion 12AA1 is smaller than the width dimension (size in the Y direction) of the lead connection portion 12AB. In one example, the width dimension of the narrow portion 12AA1 is equal to the width dimension of the narrow portion 11AA1 of the first lead terminal 11. The width dimensions of the narrow portions 11AA1 and 12AA1 can be arbitrarily changed. Furthermore, the length dimension (size in the Y direction) of the narrow portion 12AA1 is smaller than the length dimension (size in the Y direction) of the narrow portion 11AA1.

[0086] A through hole 12AD is formed in the wire connection portion 12AA. The through hole 12AD is formed in a portion of the wire connection portion 12AA that is closer to the lead connection portion 12AB than the recessed portion 12AC. The through hole 12AD is filled with a sealing resin 90. In one example, the diameter of the through hole 12AD is equal to the diameter of the through hole 11AD of the first lead terminal 11. Note that the diameters of the through holes 11AD and 12AD can be changed as desired.

[0087] A curved surface is formed at a corner portion of the wire connection portion 12AA corresponding to the curved recess 11AC3 of the first lead terminal 11. In a plan view, the arc length of the curved surface is smaller than the arc length of the curved recess 11AC3. In a plan view, it can be said that the radius of curvature of the curved surface is smaller than the radius of curvature of the curved recess 11AC3. In addition, in a plan view, it can be said that the arc length of the curved surface is smaller than the arc length of the curved recess 12AC3. In a plan view, it can be said that the radius of curvature of the curved surface is smaller than the radius of curvature of the curved recess 12AC3.

[0088] The lead connection portion 12AB extends along the X direction. When viewed from the X direction, the lead connection portion 12AB is disposed at a position overlapping the first tip side protrusion 38A of the first die pad 30. The lead connection portion 12AB is connected to the first outer lead portion 12B.

[0089] The first lead terminal 13 is formed in an L-shape in a plan view 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.

[0090] The wire connection portion 13AA fits into the recess portion 12AC of the first lead terminal 12. The wire connection portion 13AA extends in the Y direction. The lead connection portion 13AB extends along the X direction. When viewed from the X direction, the lead connection portion 13AB is disposed at a position overlapping the second tip side protrusion 38B of the first die pad 30. The lead connection portion 13AB is connected to the first outer lead portion 13B.

[0091] 9, the first inner lead portion 14A of the first lead terminal 14 is connected to the connection portion 39 of the first die pad 30. The first inner lead portion 14A extends in the X direction from the connection portion 39 toward the first sealing side surface 93. The width dimension (size in the Y direction) of the first inner lead portion 14A is smaller than the size of the connection portion 39 in the Y direction. The first inner lead portion 14A is connected to the center of the connection portion 39 in the Y direction. The first inner lead portion 14A is connected to the first outer lead portion 14B.

[0092] 10 , each of the first inner lead portions 15A, 16A of the first lead terminals 15, 16 includes a portion that fits into the third recessed portion 36C of the first die pad 30. Each of the first inner lead portions 15A, 16A is disposed closer to the first sealing side surface 93 than the second recessed portion 36B of the first die pad 30. Each of the first inner lead portions 17A, 18A of the first lead terminals 17, 18 includes a portion that fits into the second recessed portion 36B.

[0093] The shapes of the first lead terminals 16 to 18 in a plan view are symmetrical to the shapes of the first lead terminals 11 to 13 in a plan view with respect to an imaginary line extending in the X direction at the center in the Y direction of the sealing resin 90. Therefore, in the following, the general configuration of the first lead terminals 16 to 18 will be described, and a detailed description of the configuration of the first lead terminals 16 to 18 will be omitted.

[0094] The first lead terminal 18 includes a wire connection portion 18AA and a lead connection portion 18AB extending from the wire connection portion 18AA toward the first sealing side surface 93. The wire connection portion 18AA is recessed into the second recessed portion 36B of the first die pad 30. The wire connection portion 18AA includes a recessed portion 18AC. The recessed portion 18AC is recessed from one of both X-direction ends of the wire connection portion 18AA that is closer to the first sealing side surface 93 toward the second tip-side protrusion 38B of the first die pad 30. The recessed portion 18AC includes a first surface 18AC1 extending in the X-direction, a second surface 18AC2 extending in the Y-direction, and a curved recessed portion 18AC3 formed between the first surface 18AC1 and the second surface 18AC2. In one example, the arc length of the curved recessed portion 18AC3 is greater than the arc length of the second tip-side curved surface 35B in a plan view. In a plan view, the radius of curvature of the curved recess 18AC3 is greater than the radius of curvature of the second distal curved surface 35B. The width dimension (size in the X direction) of the narrow portion 18AA1 of the wire connection portion 18AA, which is narrowed by the recess 18AC, is smaller than the width dimension (size in the Y direction) of the lead connection portion 18AB.

[0095] A through hole 18AD is formed in the wire connection portion 18AA. The through hole 18AD is filled with a sealing resin 90. An inclined surface 18AE is formed in the wire connection portion 18AA. The inclined surface 18AE is formed in a corner portion of the wire connection portion 18AA that is close to the second sealing side surface 94 (see FIG. 7 ) and the third sealing side surface 95.

[0096] The lead connection portion 18AB extends along the X direction. The lead connection portion 18AB is disposed closer to the third sealing side surface 95 than the first die pad 30. The lead connection portion 18AB is connected to the first outer lead portion 18B.

[0097] The first lead terminal 17 includes a wire connection portion 17AA and a lead connection portion 17AB extending from the wire connection portion 17AA toward the first sealing side surface 93. The wire connection portion 17AA fits into a recessed portion 18AC of the wire connection portion 18AA of the first lead terminal 18. The wire connection portion 17AA includes a recessed portion 17AC. The recessed portion 17AC is recessed from one of both X-direction ends of the wire connection portion 17AA that is closer to the first sealing side surface 93 toward the recessed portion 18AC of the wire connection portion 18AA of the first lead terminal 18. The recessed portion 17AC includes a first surface 17AC1 extending in the X-direction, a second surface 17AC2 extending in the Y-direction, and a curved recess 17AC3 formed between the first surface 17AC1 and the second surface 17AC2. In one example, in a plan view, the arc length of the curved recess 17AC3 is smaller than the arc length of the curved recess 18AC3 of the first lead terminal 18. In a plan view, the radius of curvature of the curved recess 17AC3 can be said to be smaller than the radius of curvature of the curved recess 18AC3. The width dimension (size in the X direction) of the narrow portion 17AA1 of the wire connection portion 17AA, which is narrowed by the recess 17AC, is smaller than the width dimension (size in the Y direction) of the lead connection portion 17AB. In one example, the width dimension of the narrow portion 17AA1 is equal to the width dimension of the narrow portion 18AA1 of the first lead terminal 18. The width dimensions of the narrow portions 17AA1 and 18AA1 can be changed as desired. Furthermore, the length dimension (size in the Y direction) of the narrow portion 17AA1 is smaller than the length dimension (size in the Y direction) of the narrow portion 18AA1.

[0098] A through hole 17AD is formed in the wire connection portion 17AA. In one example, the diameter of the through hole 17AD is equal to the diameter of the through hole 18AD of the first lead terminal 18. Note that the diameters of the through holes 17AD and 18AD can be changed as desired.

[0099] When viewed from the X direction, the lead connection portion 17AB is disposed at a position overlapping the second tip side protrusion 38B of the first die pad 30. The lead connection portion 17AB is connected to the first outer lead portion 17B.

[0100] The first lead terminal 16 includes a wire connection portion 16AA and a lead connection portion 16AB extending from the wire connection portion 16AA toward the first sealing side surface 93. The wire connection portion 16AA extends into the recess portion 17AC of the first lead terminal 17. That is, the wire connection portion 16AA extends into both the third recess portion 36C of the first die pad 30 and the recess portion 17AC of the first lead terminal 17. The lead connection portion 16AB is connected to the first outer lead portion 16B.

[0101] 10 , the first lead terminal 15 is formed in a T-shape in a plan view. The first lead terminal 15 includes a wire connection portion 15AA and a lead connection portion 15AB extending from the wire connection portion 15AA toward the first sealing side surface 93.

[0102] The wire connection portion 15AA extends into the third recess 36C of the first die pad 30. The wire connection portion 15AA extends in the Y direction. An inclined surface 15AC is formed in a corner portion of the wire connection portion 15AA that is closer to the first die pad 30 and the first lead terminal 16. The inclined surface 15AC is inclined toward the first lead terminal 16 as it extends from the first die pad 30 toward the first sealing side surface 93.

[0103] The lead connection portion 16AB extends along the X direction. When viewed from the X direction, the lead connection portion 16AB is disposed closer to the fourth sealing side surface 96 (see FIG. 7 ) than the second recessed portion 36B of the first die pad 30. The lead connection portion 16AB is connected to the first outer lead portion 16B.

[0104] 9 and 10, first lead terminals 11 to 13 and 15 to 18 are disposed apart from first die pad 30 and therefore correspond to "first separate terminals." On the other hand, first lead terminal 14 is integrated with first die pad 30 and therefore corresponds to "first connection terminal." Wire connection portions 11AA to 13AA and 15AA to 18AA of first lead terminals 11 to 13 and 15 to 18 correspond to "second portions," and lead connection portions 11AB to 13AB and 15AB to 18AB correspond to "first portions."

[0105] Next, the detailed cross-sectional structures of the wire connection portions 11AA to 13AA and 15AA to 18AA of the first inner lead portions 11A to 13A and 15A to 18A will be described. Figure 11 shows the cross-sectional structure of the wire connection portion 11AA of the first inner lead portion 11A. Note that the cross-sectional structures of the wire connection portions 12AA, 13AA and 15AA to 18AA of the first inner lead portions 12A, 13A and 15A to 18A are similar to the cross-sectional structure of the wire connection portion 11AA, and therefore detailed description thereof will be omitted.

[0106] 11 , the inner lead body 20B of the wire connection portion 11AA 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 second side surface 34 (see FIG. 9 ) 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 ).

[0107] In the cross-sectional view of Fig. 11, the tip surface 24B is formed in a concave shape that is recessed away from the first die pad 30. 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. 11 can be changed as desired.

[0108] 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 11AA. The thickness of the plating layer 29 is thinner than the thickness of the inner lead body 20B in the wire connection portion 11AA.

[0109] 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 11AB (see FIG. 9 ) 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 ).

[0110] 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.

[0111] Furthermore, the plating layer 29 does not cover the tip surface 24B of the wire connection portion 11AA. 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.

[0112] The detailed planar structure of the second die pad 50A will be described. As shown in FIG. 12 , the shape of the second die pad 50A in plan view is a substantially rectangular shape with the Y direction as the longitudinal direction and the X direction as the lateral direction. The second die pad 50A includes a die pad facing surface 51A, a lead side surface 52A, a third side surface 53A, and a fourth side surface 54A. The die pad facing surface 51A is the surface of the second die pad 50A that faces the first die pad 30 and extends along the Y direction in plan view. The lead side surface 52A is the surface of the second die pad 50A opposite the die pad facing surface 51A and extends along the Y direction in plan view. The third side surface 53A is the side surface of both ends of the second die pad 50A in the Y direction that is closer to the third sealing side surface 95 and extends along the X direction in plan view. The fourth side surface 54A is a side surface closer to the fourth sealing side surface 96 (see FIG. 7) of both ends of the second die pad 50A in the Y direction, and extends along the X direction in a plan view.

[0113] The second die pad 50A further has a first curved surface 55AA and a second curved surface 55AB. The first curved surface 55AA and the second curved surface 55AB are formed at a position facing the third die pad 50B in the Y direction. The first curved surface 55AA and the second curved surface 55AB are formed at one of the two Y direction end portions of the second die pad 50A that is closer to the third die pad 50B. The first curved surface 55AA and the second curved surface 55AB can also be said to be formed at the tip portion of the second die pad 50A. The first curved surface 55AA is formed between the die pad facing surface 51A and the fourth side surface 54A. The first curved surface 55AA has a rounded chamfered shape at the portion between the die pad facing surface 51A and the fourth side surface 54A. The second curved surface 55AB is formed between a second surface 56A2 of a fourth recessed portion 56A (described later) and the fourth side surface 54A. The second curved surface 55AB has a chamfered shape at the portion between the second surface 56A2 and the fourth side surface 54A. In one example, the arc length of the first curved surface 55AA and the arc length of the second curved surface 55AB are equal in plan view. In other words, the radius of curvature of the first curved surface 55AA and the radius of curvature of the second curved surface 55AB are equal in plan view.

[0114] The second die pad 50A further has a fourth recessed portion 56A into which the second lead terminals 42-44 fit. The fourth recessed portion 56A is formed in a portion of the second die pad 50A closer to the second sealing side surface 94. The fourth recessed portion 56A is formed to be recessed in the X direction from the lead side surface 52A toward the die pad opposing surface 51A. The fourth recessed portion 56A is formed to be recessed in the Y direction from the fourth side surface 54A toward the third side surface 53A. In this way, the fourth recessed portion 56A is open toward both the second sealing side surface 94 and the fourth sealing side surface 96.

[0115] The fourth recessed portion 56A includes a first surface 56A1 extending in the X direction, a second surface 56A2 extending in the Y direction, and a curved recess 56A3 formed between the first surface 56A1 and the second surface 56A2. The first surface 56A1 is positioned closer to the third side surface 53A than the second surface 56A2 and is connected to the lead side surface 52A. In a plan view, the curved recess 56A3 is formed as an arc portion connecting the first surface 56A1 and the second surface 56A2. In one example, in a plan view, the arc length of the curved recess 56A3 is greater than the arc length of the first curved surface 55AA. In a plan view, the radius of curvature of the curved recess 56A3 can be said to be greater than the radius of curvature of the first curved surface 55AA.

[0116] The second die pad 50A further has an inclined surface 57A and a through hole 58A. The inclined surface 57A is formed to avoid interference between the second die pad 50A and the conductive member 10D. The inclined surface 57A is formed between the die pad facing surface 51A and the third side surface 53A. The inclined surface 57A is inclined from the die pad facing surface 51A toward the second sealing side surface 94 and toward the third sealing side surface 95.

[0117] The through hole 58A is formed in one of both end portions of the second die pad 50A in the Y direction, at the end closer to the third sealing side surface 95. The through hole 58A is formed in a position of the second die pad 50A closer to the third sealing side surface 95 than the fourth recessed portion 56A. In a plan view, the through hole 58A has an elongated hole shape extending in the X direction. The through hole 58A penetrates the second die pad 50A in the Z direction. The through hole 58A is filled with sealing resin 90.

[0118] The detailed planar structure of the third die pad 50B will be described. As shown in FIG. 13 , in a plan view, the third die pad 50B has a die pad facing surface 51B, a lead side surface 52B, a fifth side surface 53B, and a sixth side surface 54B. The die pad facing surface 51B is a surface facing the first die pad 30 in the X direction and extends along the Y direction in a plan view. The lead side surface 52B is a surface opposite the die pad facing surface 51B and extends along the Y direction in a plan view. The fifth side surface 53B is the end surface closest to the third sealing side surface 95 (see FIG. 7 ) of both end surfaces of the third die pad 50B in the Y direction and extends along the X direction in a plan view. The sixth side surface 54B is the end surface closest to the fourth sealing side surface 96 of both end surfaces of the third die pad 50B in the Y direction and extends along the X direction in a plan view.

[0119] The third die pad 50B further has a fifth recess 57B into which the second lead terminal 48 fits, a sixth recess 57C into which the second lead terminal 47 fits, and a seventh recess 57D into which the second lead terminal 45 fits.

[0120] The fifth recessed portion 57B is formed in a portion of the third die pad 50B closer to the fourth sealing side surface 96. The fifth recessed portion 57B is formed to be recessed from the sixth side surface 54B toward the fifth side surface 53B. The fifth recessed portion 57B is formed closer to the second sealing side surface 94 than the die pad facing surface 51B in the X direction. On the other hand, the fifth recessed portion 57B is formed so as to remove the lead side surface 52B. In other words, the fifth recessed portion 57B opens toward both the second sealing side surface 94 and the fourth sealing side surface 96. A protruding portion 58B is provided in a portion of the third die pad 50B between the fifth recessed portion 57B and the die pad facing surface 51B in the X direction. In a plan view, the protruding portion 58B extends in the Y direction. The protruding portion 58B includes the sixth side surface 54B, the die pad facing surface 51B, and the second tip-side curved surface 55BB. The protruding portion 58B faces the first die pad 30 (see FIG. 7) in the X direction. More specifically, the protruding portion 58B faces the first tip-side protruding portion 38A (see FIG. 9) of the first die pad 30.

[0121] The fifth recessed portion 57B includes a first surface 57B1 extending in the X direction, a second surface 57B2 extending in the Y direction, and a curved recessed portion 57B3 formed between the first surface 57B1 and the second surface 57B2. The first surface 57B1 is positioned closer to the fifth side surface 53B than the sixth side surface 54B. The second surface 57B2 forms a part of the side surface of the protruding portion 58B. In a plan view, the curved recessed portion 57B3 is formed as an arc portion connecting the first surface 57B1 and the second surface 57B2.

[0122] The sixth recessed portion 57C is formed in a portion of the third die pad 50B closer to the third sealing side surface 95. The sixth recessed portion 57C is formed so as to be recessed from the fifth side surface 53B toward the sixth side surface 54B. The sixth recessed portion 57C is formed closer to the second sealing side surface 94 than the die pad opposing surface 51B in the X direction. On the other hand, the sixth recessed portion 57C is formed so as to remove the lead side surface 52B. In other words, the sixth recessed portion 57C is open toward both the second sealing side surface 94 and the third sealing side surface 95.

[0123] The sixth recess 57C includes a first surface 57C1 extending in the X direction, a second surface 57C2 extending in the Y direction, and a curved recess 57C3 formed between the first surface 57C1 and the second surface 57C2. The first surface 57C1 is positioned closer to the sixth side surface 54B than the fifth side surface 53B. The length of the first surface 57C1 is shorter than the length of the first surface 57B1 of the fifth recess 57B. The length of the second surface 57C2 is longer than the length of the second surface 57B2 of the fifth recess 57B. In a plan view, the curved recess 57C3 is formed as an arc portion connecting the first surface 57C1 and the second surface 57C2. In one example, the arc length of the curved recess 57C3 is equal to the arc length of the curved recess 57B3 of the fifth recess 57B. In plan view, the radius of curvature of the curved recess 57C3 can be said to be equal to the radius of curvature of the curved recess 57B3.

[0124] The seventh recess 57D is formed between the fifth recess 57B and the sixth recess 57C in the Y direction. The seventh recess 57D is formed spaced apart from the sixth recess 57C, but is continuous with the fifth recess 57B. The seventh recess 57D is formed spaced apart from the die pad facing surface 51B in the X direction. Meanwhile, the seventh recess 57D opens toward both the second sealing side surface 94 and the fourth sealing side surface 96. The sixth recess 57C and the seventh recess 57D form a connection portion 59B to which the second lead terminal 46 of the third die pad 50B is connected. The connection portion 59B includes the lead side surface 52B.

[0125] The seventh recess 57D includes a first surface 57D1 extending in the X direction, a second surface 57D2 extending in the Y direction, and a curved recess 57D3 formed between the first surface 57D1 and the second surface 57D2. The first surface 57D1 constitutes a side surface of the connection portion 59B. The first surface 57D1 is formed in a position between the first surface 57B1 of the fifth recess 57B and the first surface 57C1 of the sixth recess 57C in the Y direction, closer to the first surface 57B1. The first surface 57D1 is connected to the lead side surface 52B. The second surface 57D2 is formed in the same position as the second surface 57C2 of the sixth recess 57C in the X direction. The length of the second surface 57D2 is shorter than the length of the second surface 57C2 of the sixth recess 57C. The length of the second surface 57D2 is shorter than the length of the second surface 57B2 of the fifth recess 57B. In a plan view, the curved recess 57D3 is formed as an arc portion connecting the first surface 57D1 and the second surface 57D2. In one example, in a plan view, the arc length of the curved recess 57D3 is equal to the arc length of the curved recess 57B3 of the fifth recess 57B. In a plan view, it can be said that the radius of curvature of the curved recess 57D3 is equal to the radius of curvature of the curved recess 57B3.

[0126] The third die pad 50B further has a first tip curved surface 55BA, a second tip curved surface 55BB, a first base curved surface 56BA, and a second base curved surface 56BB. The first tip curved surface 55BA is formed between the die pad facing surface 51B and the fifth side surface 53B. The first tip curved surface 55BA has a rounded chamfered shape at the portion between the die pad facing surface 51B and the fifth side surface 53B. The second tip curved surface 55BB is formed between the die pad facing surface 51B and the sixth side surface 54B. The second tip curved surface 55BB has a rounded chamfered shape at the portion between the die pad facing surface 51B and the sixth side surface 54B. In one example, in a plan view, the arc length of the first tip curved surface 55BA and the arc length of the second tip curved surface 55BB are equal to each other. In other words, the radius of curvature of the first distal curved surface 55BA and the radius of curvature of the second distal curved surface 55BB are equal to each other in plan view.

[0127] The first tip curved surface 55BA faces the first curved surface 55AA (see FIG. 12 ) of the second die pad 50A in the Y direction. In a plan view, the arc length of the first tip curved surface 55BA is equal to the arc length of the first curved surface 55AA. In a plan view, the radius of curvature of the first tip curved surface 55BA can also be said to be equal to the radius of curvature of the first curved surface 55AA. In a plan view, the arc lengths of the first tip curved surface 55BA and the second tip curved surface 55BB are smaller than the arc length of the curved recess 57C3 of the sixth recess 57C. In a plan view, the radius of curvature of the first tip curved surface 55BA and the second tip curved surface 55BB can also be said to be smaller than the radius of curvature of the curved recess 57C3 of the sixth recess 57C. In a plan view, the arc lengths of the first and second distal curved surfaces 55BA and 55BB are smaller than the arc length of the curved recess 57B3 of the fifth recess 57B. In other words, in a plan view, the radii of curvature of the first and second distal curved surfaces 55BA and 55BB are smaller than the radii of curvature of the curved recess 57B3 of the fifth recess 57B.

[0128] The first base-side curved surface 56BA is formed between the second surface 57C2 of the sixth recess 57C and the fifth side surface 53B. The first base-side curved surface 56BA has a rounded chamfered shape at the portion between the second surface 57C2 of the sixth recess 57C and the fifth side surface 53B. The second base-side curved surface 56BB is formed between the fifth recess 57B and the seventh recess 57D. The second base-side curved surface 56BB has a rounded chamfered shape at the portion between the second surface 57B2 of the fifth recess 57B and the first surface 57D1 of the seventh recess 57D. In one example, in a plan view, the arc length of the first base-side curved surface 56BA is equal to the arc length of the second base-side curved surface 56BB. In other words, the radius of curvature of the first base-end curved surface 56BA and the radius of curvature of the second base-end curved surface 56BB are equal to each other in plan view.

[0129] The first base-side curved surface 56BA faces the second curved surface 55AB of the second die pad 50A in the Y direction. In a plan view, the arc length of the first base-side curved surface 56BA is equal to the arc length of the second curved surface 55AB. In a plan view, the radius of curvature of the first base-side curved surface 56BA can also be said to be equal to the radius of curvature of the second curved surface 55AB. In a plan view, the arc lengths of the first base-side curved surface 56BA and the second base-side curved surface 56BB are smaller than the arc length of the curved recess 57B3 of the fifth recess 57B. In a plan view, the radius of curvature of the first base-side curved surface 56BA and the second base-side curved surface 56BB can also be said to be smaller than the radius of curvature of the curved recess 57B3 of the fifth recess 57B. In a plan view, the arc lengths of the first and second proximal curved surfaces 56BA and 56BB are smaller than the arc length of the curved recess 57C3 of the sixth recess 57C. In other words, in a plan view, the radii of curvature of the first and second proximal curved surfaces 56BA and 56BB are smaller than the radii of curvature of the curved recess 57C3 of the sixth recess 57C.

[0130] The following describes the detailed configuration of each of the second lead terminals 41 to 48. As shown in Fig. 7, of the second lead terminals 41 to 48, the second lead terminals 41 to 44 are provided around the second die pad 50A. The second lead terminals 45 to 48 are provided around the third die pad 50B.

[0131] 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 configuration of the second inner lead portions 41A to 48A will be described below.

[0132] 12 , the second inner lead portion 41A of the second lead terminal 41 is connected to the second die pad 50A. The second inner lead portion 41A is connected to a portion of the second die pad 50A that is closer to the third sealing side surface 95 than the fourth recessed portion 56A. In the first embodiment, the second inner lead portion 41A is connected to one of both ends of the second die pad 50A in the Y direction that is closer to the third sealing side surface 95. The second inner lead portion 41A extends from the second die pad 50A toward the first sealing side surface 93 in the X direction.

[0133] Each of the first inner lead portions 42A to 44A of the second lead terminals 42 to 44 includes a portion that fits into the fourth recessed portion 56A of the third die pad 50B. The second lead terminal 42 is formed in an L-shape in plan view. The second lead terminal 42 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.

[0134] The wire connection portion 42AA enters the fourth recessed portion 56A of the second die pad 50A. The wire connection portion 42AA extends in the Y direction. The lead connection portion 42AB extends along the X direction. The lead connection portion 42AB is disposed closer to the third sealing side surface 95 than the second chip 70. The lead connection portion 42AB is connected to the second outer lead portion 42B.

[0135] The second lead terminal 43 is formed in an L-shape in a plan view 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.

[0136] The wire connection portion 43AA is recessed into the fourth recess 56A of the second die pad 50A. The wire connection portion 43AA extends in the Y direction. The length dimension (size in the Y direction) of the wire connection portion 43AA is smaller than the length dimension (size in the Y direction) of the wire connection portion 42AA.

[0137] An inclined surface 43AC is formed in a corner portion of the wire connection portion 43AA that is closer to the second lead terminal 42 and the second die pad 50A. The inclined surface 43AC is inclined toward the second lead terminal 42 as it extends from the second die pad 50A toward the second sealing side surface 94.

[0138] The lead connection portion 43AB extends along the X direction. When viewed from the X direction, the lead connection portion 43AB is disposed at a position overlapping the second chip 70. The lead connection portion 43AB is connected to the second outer lead portion 43B.

[0139] The second lead terminal 44 is formed in a T-shape in a plan view and 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.

[0140] The wire connection portion 44AA is recessed into the fourth recess 56A of the second die pad 50A. The wire connection portion 44AA extends in the Y direction. The length dimension (size in the Y direction) of the wire connection portion 44AA is smaller than the length dimension (size in the Y direction) of the wire connection portion 42AA.

[0141] The lead connection portion 44AB extends in the X direction. The lead connection portion 44AB is disposed closer to the fourth sealing side surface 96 (see FIG. 7) than the second chip 70. The lead connection portion 44AB is connected to the second outer lead portion 44B.

[0142] 13 , the second inner lead portion 45A of the second lead terminal 45 includes a portion that enters the sixth recessed portion 57C of the third die pad 50B. The second inner lead portion 47A of the second lead terminal 47 includes a portion that enters the seventh recessed portion 57D. The second inner lead portion 48A of the second lead terminal 48 includes a portion that enters the fifth recessed portion 57B. The second inner lead portion 46A of the second lead terminal 46 is connected to the third die pad 50B.

[0143] The second lead terminal 48 is formed in an L-shape in a plan view and includes a wire connection portion 48AA and a lead connection portion 48AB extending from the wire connection portion 48AA toward the second sealing side surface 94.

[0144] The wire connection portion 48AA is recessed into the fifth recess 57B of the third die pad 50B. The wire connection portion 48AA extends in the Y direction. The wire connection portion 48AA includes a recess 48AC.

[0145] The recessed portion 48AC is formed in a portion of the wire connection portion 48AA closer to the second lead terminal 47. The recessed portion 48AC is recessed from one of the ends of the wire connection portion 48AA in the X direction closer to the second sealing side surface 94 toward the protruding portion 58B of the third die pad 50B. The recessed portion 48AC includes a first surface 48AC1 extending in the X direction, a second surface 48AC2 extending in the Y direction, and a curved recessed portion 48AC3 formed between the first surface 48AC1 and the second surface 48AC2. The first surface 48AC1 is positioned closer to the second lead terminal 47 than the lead connection portion 48AB. The second surface 48AC2 is positioned so as to overlap the second lead terminal 47 when viewed from the X direction. In a plan view, the curved recessed portion 48AC3 is formed as an arc portion connecting the first surface 48AC1 and the second surface 48AC2. In one example, in a plan view, the arc length of the curved recess 48AC3 is greater than the arc length of the second distal curved surface 55BB. In a plan view, the radius of curvature of the curved recess 48AC3 can be said to be greater than the radius of curvature of the second distal curved surface 55BB. A narrow portion 48AA1 of the wire connection portion 48AA, whose width is narrowed by the recess 48AC, extends along the Y direction. The width dimension (size in the X direction) of the narrow portion 48AA1 is greater than the width dimension (size in the Y direction) of the lead connection portion 48AB.

[0146] A through hole 48AD is formed in the wire connection portion 48AA. The through hole 48AD is formed in a portion of the wire connection portion 48AA that is closer to the lead connection portion 48AB than the recessed portion 48AC. The through hole 48AD has a circular shape in a plan view. The through hole 48AD is filled with a sealing resin 90. The shape and size of the through hole 48AD can be changed as desired.

[0147] The wire connection portion 48AA has an inclined surface 48AE formed in a corner portion of the wire connection portion 48AA that is closer to the protruding portion 58B and the fourth sealing side surface 96. In a plan view, the inclined surface 48AE is inclined from the third sealing side surface 95 (see FIG. 7 ) toward the fourth sealing side surface 96 as it moves from the protruding portion 58B toward the second sealing side surface 94.

[0148] The lead connection portion 48AB extends along the X direction. The lead connection portion 48AB is disposed closer to the fourth sealing side surface 96 than the third die pad 50B. The lead connection portion 48AB is connected to the second outer lead portion 48B.

[0149] The second lead terminal 47 is formed in an L-shape in a plan view and includes a wire connection portion 47AA and a lead connection portion 47AB extending from the wire connection portion 47AA toward the second sealing side surface 94.

[0150] The wire connection portion 47AA extends into the recessed portion 48AC of the wire connection portion 48AA of the second lead terminal 48. That is, the wire connection portion 47AA extends into both the recessed portion 48AC of the wire connection portion 48AA of the second lead terminal 48 and the seventh recessed portion 57D of the third die pad 50B. The wire connection portion 47AA extends in the Y direction. The width dimension (size in the X direction) of the wire connection portion 47AA is smaller than the width dimension (size in the X direction) of the wire connection portion 48AA of the second lead terminal 48.

[0151] The lead connection portion 47AB extends along the X direction. The lead connection portion 47AB is disposed closer to the fourth sealing side surface 96 than the sixth recessed portion 57C of the second die pad 50A. The lead connection portion 47AB is connected to the second outer lead portion 47B.

[0152] The second inner lead portion 46A of the second lead terminal 46 is connected to the connection portion 59B of the third die pad 50B. The width dimension (size in the Y direction) of the second inner lead portion 46A is smaller than the width dimension (size in the Y direction) of the connection portion 59B. The second inner lead portion 46A is connected to a portion of the connection portion 59B closer to the fourth sealing side surface 96.

[0153] The second lead terminal 45 is formed in a T-shape in a plan view and includes a wire connection portion 45AA and a lead connection portion 45AB extending from the wire connection portion 45AA toward the second sealing side surface 94.

[0154] The wire connection portion 45AA enters the sixth recessed portion 57C of the third die pad 50B. The wire connection portion 45AA extends in the Y direction. The lead connection portion 45AB extends along the X direction. When viewed from the X direction, the lead connection portion 45AB is disposed closer to the third sealing side surface 95 (see FIG. 7 ) than the third chip 80. The lead connection portion 45AB is connected to the second outer lead portion 45B.

[0155] As shown in FIGS. 12 and 13 , the second lead terminals 42 to 44 are disposed apart from the second die pad 50A, and therefore correspond to the "second separate terminals." The second lead terminals 45, 47, and 48 are disposed apart from the third die pad 50B, and therefore correspond to the "third separate terminals." On the other hand, the second lead terminal 41 is integrated with the second die pad 50A, and therefore corresponds to the "second connection terminal." The second lead terminal 46 is integrated with the third die pad 50B, and therefore corresponds to the "third connection terminal." The wire connection portions 42AA to 44AA of the second lead terminals 42 to 44 correspond to the "fourth portion," and the lead connection portions 42AB to 44AB correspond to the "third portion." The wire connection portions 45AA, 47AA, and 48AA of the second lead terminals 45, 47, and 48 correspond to the "sixth portion," and the lead connection portions 45AB, 47AB, and 48AB correspond to the "fifth portion."

[0156] Next, the detailed cross-sectional structure of the second inner lead portions 42A to 45A, 47A, and 48A will be described. Figure 14 shows the cross-sectional structure of the wire connection portion 48AA of the second inner lead portion 48A. Note that the cross-sectional structures of the wire connection portions 42AA to 45AA and 47AA of the second inner lead portions 42A to 45A and 47A are similar to the cross-sectional structure of the wire connection portion 48AA, so detailed description thereof will be omitted. For convenience, the reference numerals relating to the second inner lead portion 48A are the same as those relating to the first inner lead portion 11A.

[0157] 14, the inner lead body 20B of the wire connection portion 48AA 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 43AA faces the same side as the inner lead surface 21B of the wire connection portion 11AA (see FIG. 11), and the inner lead back surface 22B of the wire connection portion 48AA faces the same side as the inner lead back surface 22B of the wire connection portion 11AA (see FIG. 11).

[0158] In the cross-sectional view of FIG. 14 , the tip surface 24B faces the first surface 57B1 (see FIG. 13 ) of the fifth recessed portion 57B of the third die pad 50B in the Y direction. The tip surface 24B is formed in a concave shape recessed away from the sixth side surface 54B. 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 one-third the thickness of the wire connection portion 43AA from the inner lead back surface 22B. Note that the shape of the tip surface 24B in the cross-sectional view of FIG. 14 can be changed as desired.

[0159] 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 bonding portion 11AA (see FIG. 11 ). 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 bonding portion 48AA. In one example, the thickness of the plating layer 29 of the wire bonding portion 48AA is equal to the thickness of the plating layer 29 of the wire bonding portion 11AA. Here, if the difference between the thicknesses of the plating layer 29 of the wire bonding portion 48AA and the plating layer 29 of the wire bonding portion 11AA is, for example, within 20% of the thickness of the plating layer 29 of the wire bonding portion 48AA, it can be said that the thickness of the plating layer 29 of the wire bonding portion 48AA is equal to the thickness of the plating layer 29 of the wire bonding portion 11AA.

[0160] An end surface 29A of the plating layer 29 that is closer to the tip surface 24B of the wire connection portion 48AA is formed at a position closer to the lead connection portion 48AB (see FIG. 13) 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).

[0161] 14 , 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.

[0162] Furthermore, the plating layer 29 does not cover the tip surface 24B of the wire connection portion 48AA. 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.

[0163] Next, we will explain the schematic configuration of the first chip 60, the second chip 70, and the third chip 80. As shown in Figure 8, the first chip 60 mounted on the first die pad 30 has a chip front surface 61, a chip back surface 62 (see Figure 21) 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.

[0164] 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 which 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 which the second chip 70 and the third chip 80 are 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.

[0165] The first chip 60 has a plurality of first electrode pads 67 (six in the first embodiment), a plurality of second electrode pads 68 (seven in the first embodiment), and a plurality of third electrode pads 69 (two in the first embodiment). Each of the first electrode pads 67, each of the second electrode pads 68, and each of the third electrode pads 69 are provided so as to be exposed from the chip surface 61. The number of each of the second electrode pads 68 and the third electrode pads 69 can be changed as desired.

[0166] 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.

[0167] 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.

[0168] The multiple first electrode pads 67 are electrode pads electrically connected to the second chip 70 and the third chip 80. The multiple first electrode pads 67 are provided at positions closer to the second chip side surface 64 than the center of the chip surface 61 in the X direction 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. The multiple first electrode pads 67 can be divided into three first electrode pads 67 electrically connected to the second chip 70 and three first electrode pads 67 electrically connected to the third chip 80. The three first electrode pads 67 electrically connected to the second chip 70 are arranged closer to the third chip side surface 65 on the chip surface 61. The three first electrode pads 67 electrically connected to the third chip 80 are arranged closer to the fourth chip side surface 66 on the chip surface 61.

[0169] The second electrode pads 68 are electrode pads that are individually and electrically connected to the first lead terminals 11 to 13 and 15 to 18. 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.

[0170] 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 arranged on the chip surface 61 closer to the first side surface 33 than the connection portion 39 of the first die pad 30 in a planar view. The multiple third electrode pads 69 are arranged on the chip surface 61 at an end closer to the first chip side surface 63 in a planar view.

[0171] As shown in FIG. 12, the second chip 70 mounted on the second die pad 50A 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.

[0172] The chip front surface 71 faces the side opposite to the second die pad 50A with respect to the second chip 70, and the chip back surface faces the side facing the second die pad 50A. 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 which the first chip 60 (see FIG. 7) is arranged, and the second chip side surface 74 is the chip side surface of the second chip 70 on which 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.

[0173] The second chip 70 has a plurality of (three in the first embodiment) first electrode pads 77, a plurality of (four 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.

[0174] 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.

[0175] 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.

[0176] The multiple first electrode pads 77 are electrode pads that are individually and electrically connected to three first electrode pads 67 that are closer to the third chip side surface 65 among 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.

[0177] The second electrode pads 78 are electrode pads that are individually and electrically connected to the second lead terminals 42, 43. The second electrode pads 78 are provided at positions closer to the fourth chip side surface 76 than the center of the chip surface 71 in the Y direction in a plan view.

[0178] The multiple third electrode pads 79 are electrode pads electrically connected to the second die pad 50A. Each third electrode pad 79 has the same potential as the second die pad 50A, i.e., the second ground potential. The multiple third electrode pads 79 are provided at the ends of the chip surface 71 in the Y direction that are closer to the third sealing side surface 95 in a plan view. The multiple third electrode pads 79 are arranged at the same positions as each other in the Y direction and spaced apart from each other in the X direction.

[0179] As shown in FIG. 13, the third chip 80 mounted on the third die pad 50B has a chip surface 81, a chip back surface (not shown) facing the opposite side of the chip surface 81 in the Z direction, and first to fourth chip side surfaces 83 to 86 connecting the chip surface 81 and the chip back surface.

[0180] The chip front surface 81 faces the side opposite to the third die pad 50B with respect to the third chip 80, and the chip back surface faces the side facing the third die pad 50B. The first chip side surface 83 and the second chip side surface 84 constitute both end faces of the third chip 80 in the X direction in a plan view. The first chip side surface 83 is the chip side surface of the third chip 80 on which the first chip 60 (see FIG. 7) is arranged, and the second chip side surface 84 is the chip side surface of the third chip 80 on which the second lead terminals 41 to 48 are arranged. The third chip side surface 85 and the fourth chip side surface 86 constitute both end faces of the third chip 80 in the Y direction in a plan view. The third chip side surface 85 is the chip side surface closer to the third sealing side surface 95 of the sealing resin 90, and the fourth chip side surface 86 is the chip side surface closer to the fourth sealing side surface 96.

[0181] The third chip 80 has a plurality of (three in the first embodiment) first electrode pads 87, a plurality of (four in the first embodiment) second electrode pads 88, and a plurality of (two in the first embodiment) third electrode pads 89. Each of the first electrode pads 87, each of the second electrode pads 88, and each of the third electrode pads 89 is provided so as to be exposed from the chip surface 81.

[0182] Each of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 may contain at least one of titanium, titanium nitride, copper, aluminum, and tungsten. In one example, each of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 has a laminated structure of titanium and copper. Note that the material constituting one or two of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 may be different from the material constituting the remaining electrode pads.

[0183] In another example, each of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 contains aluminum. In this case, each of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 exposed from the chip surface 81 has a thickness of 2 μm or more. Note that the thickness of each of the first electrode pads 87, second electrode pads 88, and third electrode pads 89 can be changed as desired.

[0184] The multiple first electrode pads 87 are electrode pads that are individually and electrically connected to three first electrode pads 67 that are closer to the fourth chip side surface 66 among the multiple first electrode pads 67 of the first chip 60. The multiple first electrode pads 87 are provided at positions closer to the first chip side surface 83 than the center in the X direction of the chip surface 81 in a plan view. The multiple first electrode pads 87 are arranged at the same positions as each other in the X direction and spaced apart from each other in the Y direction.

[0185] The second electrode pads 88 are electrode pads that are individually and electrically connected to the second lead terminals 47, 48. The second electrode pads 88 are provided at positions closer to the fourth chip side surface 86 than the center of the chip surface 81 in the Y direction in a plan view.

[0186] The multiple third electrode pads 89 are electrode pads electrically connected to the third die pad 50B. Each third electrode pad 89 has the same potential as the third die pad 50B, i.e., the third ground potential. The multiple third electrode pads 89 are provided at the ends of the chip surface 81 in the Y direction that are closer to the third sealing side surface 95 in a plan view. The multiple third electrode pads 89 are arranged at the same positions as each other in the Y direction and spaced apart from each other in the X direction.

[0187] Next, the electrical connection configuration of the first chip 60, the second chip 70, and the third chip 80 will be described. As shown in Figure 7, the signal transmission device 10 includes inter-chip wires WA that individually connect the first chip 60 to the second chip 70 and the third chip 80, first lead wires WB that individually connect the first chip 60 to the first lead terminals 11 to 13, 15, 16, and 18, and first die pad wires WC that connect the first chip 60 to the first die pad 30. The inter-chip wires WA, the first lead wires WB, and the first die pad wires WC are sealed with sealing resin 90.

[0188] Of the multiple first electrode pads 67 of the first chip 60, three first electrode pads 67 closest to the third chip side surface 65 are individually connected to the multiple first electrode pads 77 of the second chip 70 by multiple inter-chip wires WA (three in the first embodiment). This electrically connects the multiple first electrode pads 67 to the multiple first electrode pads 77 individually. Because the multiple first electrode pads 77 are arranged closer to the third sealing side surface 95 than the multiple first electrode pads 67, in plan view each inter-chip wire WA extends obliquely toward the third sealing side surface 95 as it moves from the first electrode pad 67 to the first electrode pad 77. The three inter-chip wires WA are parallel to each other in plan view.

[0189] Of the multiple first electrode pads 67 of the first chip 60, three first electrode pads 67 closest to the fourth chip side surface 66 are individually connected to the multiple first electrode pads 87 of the third chip 80 by multiple inter-chip wires WA (three in the first embodiment). This electrically connects the multiple first electrode pads 67 to the multiple first electrode pads 87 individually. Because the multiple first electrode pads 87 are positioned closer to the fourth sealing side surface 96 than the multiple first electrode pads 67, each inter-chip wire WA extends obliquely toward the fourth sealing side surface 96 as it moves from the first electrode pad 67 to the first electrode pad 87 in a planar view. The three inter-chip wires WA are parallel to each other in a planar view.

[0190] 9, 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 (four in the first embodiment). This electrically connects the first chip 60 to the first lead terminals 11 to 13. Each of the first lead terminals 11 and 12 is individually connected to the second electrode pads 68 by one first lead wire WB. The first lead terminal 13 is individually connected to the second electrode pads 68 by two first lead wires WB.

[0191] 10 , the second electrode pads 68 of the first chip 60 and the first lead terminals 15, 16, and 18 are individually connected by a plurality of first lead wires WB (four in the first embodiment). This electrically connects the first chip 60 to the first lead terminals 15, 16, and 18. Each of the first lead terminals 15, 16, and 18 is individually connected to the second electrode pads 68 by a single first lead wire WB. Meanwhile, the first lead terminal 17 is not electrically connected to the first chip 60. In other words, the first lead terminal 17 is electrically floating. In the first embodiment, the first lead terminal 17 can also be considered a dummy terminal.

[0192] The first lead wire WB is a bonding wire formed by a wire bonding device. In one example, the bonded portion of the first lead wire WB to the second electrode pad 68 is a first bond portion, and the bonded portions of the first lead terminals 11 to 13, 15, 16, and 18 are second bond portions. The first lead wire WB is connected to the wire connection portions 11AA to 13AA, 15AA, 16AA, and 18AA of the first inner lead portions 11A to 13A, 15A, 16A, and 18A of the first lead terminals 11 to 13, 15, 16, and 18.

[0193] More specifically, the wire connection portion 11AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 11AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 11AA forms the tip surface of the wire connection portion 11AA and faces the first surface 36A1 of the first recessed portion 36A of the first die pad 30 in the Y direction. The first lead wire WB is connected to an end of the wire connection portion 11AA of the first lead terminal 11 that is closer to the first chip 60.

[0194] The wire connection portion 12AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 12AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 12AA forms the tip surface of the wire connection portion 12AA and faces the first surface 36A1 of the first recessed portion 36A of the first die pad 30 in the Y direction. The first lead wire WB is connected to an end of the wire connection portion 12AA of the first lead terminal 12 that is closer to the first chip 60.

[0195] The wire connection portion 13AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 13AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 13AA forms the tip surface of the wire connection portion 13AA and faces the first surface 36A1 of the first recessed portion 36A of the first die pad 30 in the Y direction. The two first lead wires WB are connected to portions of the wire connection portion 13AA of the first lead terminal 13 that are closer to the first chip 60 than the lead connection portion 13AB.

[0196] The wire connection portion 15AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 15AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 15AA forms the tip surface of the wire connection portion 15AA and faces the second surface 36C2 of the third recessed portion 36C of the first die pad 30 in the X direction.

[0197] The wire connection portion 16AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 16AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 16AA forms the tip surface of the wire connection portion 16AA and faces the second surface 36C2 of the third recessed portion 36C of the first die pad 30 in the X direction. In addition, the side surface of the wire connection portion 16AA faces the second surface 17AC2 of the recessed portion 17AC of the first lead terminal 17.

[0198] The wire connection portion 18AA includes a side surface that intersects with the first lead wire WB connected to the wire connection portion 18AA in a plan view. This side surface faces the first die pad 30 in a plan view. In the first embodiment, the side surface of the wire connection portion 18AA forms the tip surface of the wire connection portion 18AA and faces the first surface 36B1 of the second recessed portion 36B of the first die pad 30 in the Y direction. The first lead wire WB is connected to an end of the wire connection portion 18AA that is closer to the first chip 60.

[0199] 8 , 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. This electrically connects the first chip 60 and 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 14.

[0200] 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 at the bonded portion with the third electrode pad 69 and a second bond portion at the bonded portion with the first die pad 30. In the first embodiment, the second bond portion is formed in the connection portion 39.

[0201] 7 , signal transmission device 10 includes second lead wires WD that individually connect second chip 70 and third chip 80 to multiple second lead terminals 42, 43, 47, and 48, second die pad wires WE that connect second chip 70 to second die pad 50A, and third die pad wires WF that connect third chip 80 to third die pad 50B. Second lead wires WD, second die pad wires WE, and third die pad wires WF are sealed with sealing resin 90.

[0202] 12 , the second electrode pads 78 of the second chip 70 and the second lead terminals 42, 43 are individually connected by a plurality of second lead wires WD (four in the first embodiment). This electrically connects the second chip 70 to the second lead terminals 42, 43. Each of the second lead terminals 42, 43 is individually connected to the second electrode pads 78 by two second lead wires WD. Meanwhile, the second lead terminal 44 is not electrically connected to the second chip 70. In other words, the second lead terminal 44 is electrically floating. In the first embodiment, the second lead terminal 44 can also be considered a dummy terminal.

[0203] 13 , the second electrode pads 88 of the third chip 80 are individually connected to the second lead terminals 47, 48 by a plurality of second lead wires WD (four in the first embodiment). This electrically connects the third chip 80 to the second lead terminals 47, 48. Each of the second lead terminals 47, 48 is individually connected to the second electrode pads 88 by two second lead wires WD. Meanwhile, the second lead terminal 45 is not electrically connected to the third chip 80. In other words, the second lead terminal 45 is electrically floating. In the first embodiment, the second lead terminal 45 can also be considered a dummy terminal.

[0204] 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 wire WD to the second lead terminals 42, 43, 47, 48 is a second bond portion. The second lead wire WD is connected to the wire connection portions 42AA, 43AA, 47AA, 48AA of the second inner lead portions 42A, 43A, 47A, 48A of the second lead terminals 42, 43, 47, 48.

[0205] More specifically, the wire connection portion 42AA includes a side surface that intersects with the second lead wire WD connected to the wire connection portion 42AA in a plan view. This side surface faces the second die pad 50A in a plan view. In the first embodiment, the side surface of the wire connection portion 42AA forms the tip surface of the wire connection portion 42AA and faces the second surface 56A2 of the fourth recessed portion 56A of the second die pad 50A in the Y direction.

[0206] The wire connection portion 43AA includes a side surface that intersects with the second lead wire WD connected to the wire connection portion 43AA in a plan view. This side surface faces the second die pad 50A in a plan view. In the first embodiment, the side surface of the wire connection portion 43AA forms the tip surface of the wire connection portion 43AA and faces the second surface 56A2 of the fourth recessed portion 56A of the second die pad 50A in the Y direction.

[0207] The wire connection portion 47AA includes a side surface that intersects with the second lead wire WD connected to the wire connection portion 47AA in a plan view. This side surface faces the second die pad 50A in a plan view. In the first embodiment, the side surface of the wire connection portion 47AA forms the tip surface of the wire connection portion 47AA and faces the second surface 57D2 of the seventh recessed portion 57D of the second die pad 50A in the Y direction. In addition, the side surface of the wire connection portion 47AA faces the second surface 48AC2 of the recessed portion 48AC of the wire connection portion 48AA of the second lead terminal 48.

[0208] The wire connection portion 48AA includes a side surface that intersects with the second lead wire WD connected to the wire connection portion 48AA in a planar view. This side surface faces the second die pad 50A in a planar view. In the first embodiment, the side surface of the wire connection portion 48AA forms the tip surface of the wire connection portion 48AA and faces the first surface 57B1 of the fifth recessed portion 57B of the second die pad 50A in the Y direction. The second lead wire WD is connected to an end of the wire connection portion 48AA that is closer to the third chip 80.

[0209] 12 , the multiple third electrode pads 79 of the second chip 70 and the second die pad 50A 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 50A. 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. The second die pad wires WE are connected to a portion of the second die pad 50A that is closer to the third side surface 53A than the second chip 70.

[0210] 13 , the third electrode pads 89 of the third chip 80 and the third die pad 50B are individually connected by a plurality of third die pad wires WF (two in the first embodiment). This electrically connects the third chip 80 and the third die pad 50B. Therefore, the third electrode pads 89 of the third chip 80 are at a third ground potential. It can also be said that the third electrode pads 89 are electrically connected to the second lead terminals 46. The third die pad wires WF are connected to a portion of the third die pad 50B that is closer to the fifth side surface 53B than the third chip 80.

[0211] Each of the second die pad wire WE and the third die pad wire WF is a bonding wire formed by a wire bonding apparatus. In one example, the second die pad wire WE has a first bond portion bonded to the third electrode pad 79 and a second bond portion bonded to the second die pad 50A. In one example, the third die pad wire WF has a first bond portion bonded to the third electrode pad 89 and a second bond portion bonded to the third die pad 50B.

[0212] 7, the material constituting the inter-chip wire WA is different from the material constituting each of the first lead wire WB, the first die pad wire WC, the second lead wire WD, the second die pad wire WE, and the third die pad wire WF. In one example, the first lead wire WB, the first die pad wire WC, the second lead wire WD, the second die pad wire WE, and the third die pad wire WF are made of the same material.

[0213] The inter-chip wires WA are formed of a material containing gold. The first lead wires WB, the first die pad wires WC, the second lead wires WD, the second die pad wires WE, and the third die pad wires WF are each formed of a material containing copper. In one example, the first lead wires WB, the first die pad wires WC, the second lead wires WD, the second die pad wires WE, and the third die pad wires WF are each configured with a copper wire surface coated with palladium (Pd). This allows for improved oxidation resistance and corrosion resistance compared to copper wires whose surfaces are not coated with palladium.

[0214] In addition, each of the first lead wire WB, the first die pad wire WC, the second lead wire WD, the second die pad wire WE, and the third die pad wire WF may be formed from a material containing aluminum.

[0215] In the first embodiment, a security bond WC1 is formed on the second bond portion of each first die pad wire WC, a security bond WE1 is formed on the second bond portion of each second die pad wire WE, and a security bond WF1 is formed on the second bond portion of each third die pad wire WF.

[0216] 15 shows a perspective view of the second bond portion of the third die pad wire WF and its surrounding area. Note that since the configuration of the second bond portion of the third die pad wire WF is the same as the configurations of the second bond portions of the first die pad wire WC and the second die pad wire WE, the configuration of the second bond portion of the third die pad wire WF will be described in detail, and a detailed description of the configurations of the second bond portions of the first die pad wire WC and the second die pad wire WE will be omitted.

[0217] 15, the second bond portion of the third die pad wire WF includes a joint portion WFP bonded to the third die pad 50B. The joint portion WFP is a portion that is crushed by being pressed against the third die pad 50B by the wire bonding device. The thickness of the joint portion WFP is smaller than the diameter of the third die pad wire WF.

[0218] The security bond WF1 is formed by providing a stud bump SB on the bonding portion WFP. In one example, the stud bump SB is formed by ball bonding using a wire bonding device. The bonding portion WFP is sandwiched between the third die pad 50B and the stud bump SB.

[0219] [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. 16 . The signal transmission device 10 includes a first circuit 500, a second circuit 520, a third circuit 530, a first transformer 111, and a second transformer 112. In the first embodiment, the first chip 60 includes the first circuit 500, the first transformer 111, and the second transformer 112, the second chip 70 includes the second circuit 520, and the third chip 80 includes the third circuit 530. The first transformer 111 is configured to insulate the first circuit 500 from the second circuit 520 and to enable signal exchange between the first circuit 500 and the second circuit 520. The second transformer 112 is configured to insulate the first circuit 500 from the third circuit 530 and to enable signal exchange between the first circuit 500 and the third circuit 530.

[0220] The signal transmission device 10 also has first terminals P1 to P6 which are external terminals electrically connected to the first circuit 500, and second terminals Q1 to Q6 which are external terminals electrically connected to the second circuit 520 and the third circuit 530.

[0221] The first terminal P1 is a power supply terminal (VDDI), the first terminal P2 is a regulator terminal (SLDO), the first terminal P3 is a signal input terminal (PWM), the first terminal P4 is an unused terminal (DISABLE), the first terminal P5 is a timing adjustment terminal (TNEG), and the first terminal P6 is a ground terminal (GNDI). In the first embodiment, the first terminal P1 corresponds to the first lead terminal 13, the first terminal P2 corresponds to the first lead terminal 18, the first terminal P3 corresponds to the first lead terminal 11, the first terminal P4 corresponds to the first lead terminal 15, the first terminal P5 corresponds to the first lead terminal 16, and the first terminal P6 corresponds to the first lead terminal 14. In the first embodiment, the first lead terminals 12 and 17 are dummy terminals (terminals not internally connected).

[0222] The second terminal Q1 is a ground terminal (GNDG), the second terminal Q2 is an output terminal (OUTG), the second terminal Q3 is a power supply terminal (VDDG), the second terminal Q4 is a ground terminal (GNDS), the second terminal Q5 is an output terminal (OUTS), and the second terminal Q6 is a power supply terminal (VDDS). In the first embodiment, 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 46, the second terminal Q5 corresponds to the second lead terminal 47, and the second terminal Q6 corresponds to the second lead terminal 48. In the first embodiment, the second lead terminals 44 and 45 are dummy terminals (terminals not internally connected).

[0223] The first circuit 500 includes a first transmitting unit 501, a second transmitting unit 502, a logic unit 503, an LDO (Low Dropout) unit 504, an UVLO (Under Voltage Lock Out) unit 505, a delay unit 506, Schmitt triggers 507 and 508, and resistors 509 and 510.

[0224] The first terminal P1 is electrically connected to the UVLO unit 505 and the LDO unit 504, the first terminal P2 is electrically connected to the LDO unit 504, the first terminals P3 and P4 are electrically connected to the logic unit 503, and the first terminal P5 is electrically connected to the delay unit 506. The LDO unit 504 is electrically connected to the UVLO unit 505. The UVLO unit 505, the delay unit 506, the first transmission unit 501, and the second transmission unit 502 are each electrically connected to the logic unit 503.

[0225] The first transmitting unit 501 is electrically connected to the first coil of the first transformer 111. The first transmitting unit 501 is configured to transmit the PWM signal input from the logic unit 503 to the second circuit 520 using the first transformer 111.

[0226] The second transmitting unit 502 is electrically connected to the first coil of the second transformer 112. The second transmitting unit 502 is configured to transmit the PWM signal input from the logic unit 503 to the third circuit 530 using the second transformer 112.

[0227] The logic unit 503 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 P5, and to exchange various signals with the second circuit 520 and the third circuit 530 using the first transmission unit 501 and the second transmission unit 502.

[0228] A Schmitt trigger 507 and a resistor 509 are provided in the conductive path between the first terminal P3 and the logic unit 503. An input terminal of the Schmitt trigger 507 is electrically connected to the first terminal P3, and an output terminal of the Schmitt trigger 507 is electrically connected to the logic unit 503. The resistor 509 is, for example, a pull-down resistor. A first terminal of the resistor 509 is electrically connected between the first terminal P3 and the input terminal of the Schmitt trigger 507 in the conductive path, and a second terminal of the resistor 509 is electrically connected to the first terminal P6.

[0229] A Schmitt trigger 508 and a resistor 510 are provided in the conductive path between the first terminal P4 and the logic unit 503. An input terminal of the Schmitt trigger 508 is electrically connected to the first terminal P4, and an output terminal of the Schmitt trigger 508 is electrically connected to the logic unit 503. The resistor 510 is, for example, a pull-down resistor. A first terminal of the resistor 510 is electrically connected between the first terminal P4 and the input terminal of the Schmitt trigger 508 in the conductive path, and a second terminal of the resistor 510 is electrically connected to the first terminal P6.

[0230] The LDO unit 504 is, for example, a shunt regulator, and is configured to set the voltage between the first terminal P1 and the first terminal P6 to a preset reference voltage. The UVLO unit 505 stops the operation of the logic unit 503 when the voltage of the control power supply electrically connected to the first terminal P1 falls below a threshold voltage, thereby suppressing malfunction.

[0231] The second circuit 520 includes a first receiving unit 521, a logic unit 522, a UVLO unit 523, buffer circuits 524 and 525, switching elements 526 and 527, and a resistor 528. The second terminals Q1 and Q2 are electrically connected to the logic unit 522, and the second terminal Q1 is electrically connected to the UVLO unit 523. The UVLO unit 523 and the first receiving unit 521 are electrically connected to the logic unit 522.

[0232] The first receiving unit 521 is electrically connected to the second coil of the first transformer 111. The first receiving unit 521 is configured to receive the PWM signal from the first transmitting unit 501 via the first transformer 111 and output the received PWM signal to the logic unit 522.

[0233] The UVLO unit 523 stops operation of the logic unit 522 when the voltage of the control power supply electrically connected to the second terminal Q3 falls below a threshold voltage, thereby preventing malfunction. The logic unit 522 is configured to individually control the switching elements 526 and 527. More specifically, the logic unit 522 is individually and electrically connected to the gates of the switching elements 526 and 527. A buffer circuit 524 is provided between the logic unit 522 and the gate of the switching element 526. An input terminal of the buffer circuit 524 is electrically connected to the logic unit 522, and an output terminal of the buffer circuit 524 is electrically connected to the gate of the switching element 526. A buffer circuit 525 is provided between the logic unit 522 and the gate of the switching element 527. An input terminal of the buffer circuit 525 is electrically connected to the logic unit 522, and an output terminal of the buffer circuit 525 is electrically connected to the gate of the switching element 527.

[0234] A p-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used as the switching element 526, and an n-channel MOSFET is used as the switching element 527. The source of the switching element 526 is electrically connected to the second terminal Q3, and the drain of the switching element 526 is electrically connected to the drain of the switching element 527. The source of the switching element 527 is electrically connected to the second terminal Q1. The node between the drain of the switching element 526 and the drain of the switching element 527 is electrically connected to the second terminal Q2. A resistor 528 is provided between the gate and drain of the switching element 526.

[0235] The third circuit 530 includes a second receiving unit 531, a logic unit 532, a UVLO unit 533, buffer circuits 534 and 535, switching elements 536 and 537, and a resistor 538. The second terminals Q4 and Q5 are electrically connected to the logic unit 532, and the second terminal Q6 is electrically connected to the UVLO unit 533. The UVLO unit 533 and the second receiving unit 531 are electrically connected to the logic unit 532.

[0236] The second receiving unit 531 is electrically connected to the second coil of the second transformer 112. The second receiving unit 531 is configured to receive the PWM signal from the second transmitting unit 502 via the second transformer 112 and output the received PWM signal to the logic unit 532.

[0237] The UVLO unit 533 stops operation of the logic unit 532 when the voltage of the control power supply electrically connected to the second terminal Q6 falls below a threshold voltage, thereby preventing malfunction. The logic unit 532 is configured to individually control the switching elements 536 and 537. More specifically, the logic unit 532 is electrically connected to the gates of the switching elements 536 and 537 individually. A buffer circuit 534 is provided between the logic unit 532 and the gate of the switching element 536. An input terminal of the buffer circuit 534 is electrically connected to the logic unit 532, and an output terminal of the buffer circuit 534 is electrically connected to the gate of the switching element 536. A buffer circuit 535 is provided between the logic unit 532 and the gate of the switching element 537. An input terminal of the buffer circuit 535 is electrically connected to the logic unit 532, and an output terminal of the buffer circuit 535 is electrically connected to the gate of the switching element 537.

[0238] A p-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used as the switching element 536, and an n-channel MOSFET is used as the switching element 537. The source of the switching element 536 is electrically connected to the second terminal Q6, and the drain of the switching element 536 is electrically connected to the drain of the switching element 537. The source of the switching element 537 is electrically connected to the second terminal Q4. The node between the drain of the switching element 536 and the drain of the switching element 537 is electrically connected to the second terminal Q5. A resistor 538 is provided between the gate and drain of the switching element 536.

[0239] [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. 17 to 26. FIG.

[0240] 17 to 20 show a schematic planar structure of an example of the internal configuration of the first chip 60. Figures 21 to 26 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 21 to 26.

[0241] (Planar Structure of First Chip) Fig. 17 shows a schematic planar structure of an example of the internal configuration of the first chip 60 near the chip surface 61. Fig. 18 is an enlarged view of an insulating transformer region 110, which will be described later, in Fig. 17. Fig. 19 shows a schematic planar structure of an example of the internal structure of the first chip 60 near the chip back surface 62. Fig. 20 is an enlarged view of the insulating transformer region 110 in Fig. 19.

[0242] 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.

[0243] 16 are formed in the circuit region 120. These components include a first transmission unit 501, a second transmission unit 502, a logic unit 503, an LDO unit 504, and a UVLO unit 505. In the following description, the components of the first circuit 500 other than the first transformer 111 and the second transformer 112 may be referred to as "plurality of first function units" and "plurality of circuit elements."

[0244] 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.

[0245] A first transformer 111 and a second transformer 112 are formed in the isolation transformer region 110. The first transformer 111 and the second transformer 112 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. 17 , the first transformer 111 is arranged closer to the third chip side surface 65 in the isolation transformer region 110, and the second transformer 112 is arranged closer to the fourth chip side surface 66 in the isolation transformer region 110.

[0246] 17 and 19, the first transformer 111 includes a first front-side coil 111A and a first back-side coil 111B, a second front-side coil 112A and a second back-side coil 112B, and the second transformer 112 includes a third front-side coil 113A and a third back-side coil 113B, and a fourth front-side coil 114A and a fourth back-side coil 114B.

[0247] 17, 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.

[0248] 19, 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.

[0249] 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.

[0250] 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. In one 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. In another 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.

[0251] 17, 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.

[0252] 18, 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.

[0253] 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.

[0254] 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.

[0255] 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.

[0256] 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.

[0257] 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.

[0258] 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.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] 17 and 18, 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.

[0263] As shown in FIG. 20 , the first back-side coil 111B is disposed opposite the first front-side coil 111A (see FIG. 18 ) 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 first transmitter 501 (see FIG. 16 ) in 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 first transmitting unit 501 in the circuit area 120 .

[0264] The second back-side coil 112B is positioned opposite the second front-side coil 112A (see FIG. 18 ) 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 first transmitter 501 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 first transmitter 501 of the circuit area 120.

[0265] The third back-side coil 113B is disposed opposite the third front-side coil 113A (see FIG. 18 ) in the Z direction. The third back-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 second transmitter 502 (see FIG. 16 ) of the circuit area 120. The third inner coil end portion 113B3 is connected to a third wiring (not shown). The third wiring is electrically connected to the second transmitting unit 502 in the circuit area 120 .

[0266] The fourth back-side coil 114B is positioned opposite the fourth front-side coil 114A (see FIG. 18 ) 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 second transmitter 502 of the circuit area 120. The fourth inner coil end 114B3 is connected to a fourth wiring (not shown). The fourth wiring is electrically connected to the second transmitter 502 of the circuit area 120.

[0267] 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.

[0268] 18, 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.

[0269] 20 , 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 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.

[0270] 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.

[0271] As shown in FIG. 17 , 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 111 and the second transformer 112 of 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. 21 ) in the Z direction than the plurality of wiring layers 121. In one example, although not shown in FIG. 19 , 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.

[0272] 17 and 19 , 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. 17 , the front-side outer periphery guard ring 101 is connected to a 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.

[0273] 19 , 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.

[0274] 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.

[0275] (Cross-sectional structure of first chip) A cross-sectional structure of the insulating transformer region 110 will be described as an example of the internal configuration of the first chip 60. Note that in the insulating transformer region 110, the first transformer 111 and the second transformer 112 have the same configuration, and therefore, the following describes in detail the configuration of the first transformer 111, and omits a detailed description of the second transformer 112.

[0276] Fig. 21 shows a cross-sectional structure of the first transformer 111 taken along line F21-F21 in Fig. 17. Fig. 22 is an enlarged view of a portion of the first transformer 111 in Fig. 21. Fig. 23 is an enlarged view of a portion F23 of the first front-surface side coil 111A of the first transformer 111 in Fig. 22, and Fig. 24 is an enlarged view of a portion F24 of the first back-surface side coil 111B of the first transformer 111 in Fig. 22. Note that hatching lines have been omitted in Fig. 21 to facilitate understanding of the drawing.

[0277] 21 , the first chip 60 includes the above-described substrate 130 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. Furthermore, instead of a semiconductor substrate, the substrate 130 may be an insulating substrate formed of a material containing glass, or an insulating substrate formed of a material containing ceramics such as alumina.

[0278] Wide bandgap semiconductors are semiconductor substrates with a bandgap of 2.0 eV or more. Wide bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), and gallium oxide (GaO). ２ O ３ The compound semiconductor may include at least one of aluminum nitride (AlN), indium nitride (InN), gallium nitride, and gallium arsenide (GaAs).

[0279] 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.

[0280] 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 (SiO２ ) 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.

[0281] 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.

[0282] On the element insulating layer 150, a plurality of first electrode pads 67A to 67F (not shown in FIG. 21, see FIG. 18), a passivation film 161, and a protective film 162 (see FIG. 22) are formed.

[0283] 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.

[0284] As shown in FIG. 22 , 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.

[0285] 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. 21 , the thickness of the passivation film 161 is about 1.3 μm.

[0286] 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.

[0287] The first surface side coil 111A and the first back side coil 111B of the first transformer 111 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.

[0288] As shown in Fig. 23 , 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. 22 ) 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.

[0289] 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.

[0290] 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.

[0291] 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).

[0292] 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. 22 ). 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.

[0293] The width of coil surface 171 of conductor 170 (the length in the X direction in FIG. 23 ) is longer than the thickness of conductor 170. In one example, the width of coil surface 171 is more than twice the thickness of conductor 170. In another example, the width of coil surface 171 is less than three times the thickness of conductor 170. In the example of FIG. 23 , the width of coil surface 171 is approximately 6.8 μm.

[0294] 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.

[0295] In FIG. 23 , 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. 23, the distance between the conductors is about 1 µm.

[0296] 22 and 24, 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.

[0297] As shown in Fig. 22, 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. 24, 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. 24).

[0298] 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. 24 , the coil layer 111BA is offset toward the first chip side surface 63 (see FIG. 17 ) with respect to the first surface side coil 111A (see FIG. 22 ). The coil layer 111BB is offset toward the second chip side surface 64 (see FIG. 17 ) with respect to the first surface side coil 111A.

[0299] 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.

[0300] 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.

[0301] 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.

[0302] 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.

[0303] 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.

[0304] 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.

[0305] 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.

[0306] As shown in FIG. 22 , 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.

[0307] The width of the conductor 180 (the length in the X direction in FIG. 22 ) 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.

[0308] 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. 22 , 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.

[0309] 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. 22 , the inter-wire distance is approximately 0.8 μm.

[0310] 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.

[0311] 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.

[0312] 25 and 26, 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. 17 and a substrate-side wiring layer 122 disposed closer to the substrate 130 than the wiring layer 121.

[0313] 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 111. 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. 25, the thickness of the wiring layer 121 is 2.8 µm.

[0314] 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.

[0315] 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. 25, 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.

[0316] 26, the first via 123 includes a barrier layer 123A and a metal layer 123B, similar to, for example, the conductive wire 170. The materials constituting the barrier layer 123A and the metal layer 123B are the same as, for example, the materials constituting the barrier layer 174 and the metal layer 175 of the conductive wire 170 (both see FIG. 23).

[0317] 25, 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. 25, 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.

[0318] As shown in FIG. 26 , 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. 26, the thickness of the first wiring layer 122A is, for example, 0.52 μm, and the thickness of the second wiring layer 122B and the third wiring layer 122C is, for example, 0.93 μm. 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.

[0319] [Effects] 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 to 13, 15, 16, and 18. 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.

[0320] 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.

[0321] 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.

[0322] (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.

[0323] (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 42, 43. The signal transmission device 10 further includes a plurality of second lead wires WD that individually connect the third chip 80 to the second lead terminals 47, 48. These second lead wires WD are formed from a material containing copper or aluminum.

[0324] 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.

[0325] (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.

[0326] (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.

[0327] (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.

[0328] (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.

[0329] 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.

[0330] (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 50A. The second die pad wire WE is made of a material containing copper or aluminum. This configuration provides the same effect as that described in (1-3) above.

[0331] (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.

[0332] (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 50A. This configuration provides the same effect as in (1-7) above.

[0333] (1-11) The signal transmission device 10 further includes a third die pad wire WF that connects the third chip 80 and the third die pad 50B. The third die pad wire WF is made of a material containing copper or aluminum. This configuration provides the same effect as the effect described in (1-3) above.

[0334] (1-12) The third die pad wire WF is a copper wire coated with palladium, which provides the same effect as that of (1-2) above.

[0335] (1-13) A security bond WF1 is formed at the joint between the third die pad wire WF, which is the second bond portion of the third die pad wire WF, and the third die pad 50B. This configuration provides the same effect as in (1-7) above.

[0336] (1-14) Each of the first electrode pads 67, each of the second electrode pads 68, and each of the 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.

[0337] (1-15) 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, the second die pad wire WE, and the third die pad wire WF.

[0338] (1-16) A plating layer 29 is formed on the inner lead surface 21B of the wire connection portion 11AA of the first inner lead portion 11A of the first lead terminal 11. The plating layer 29 is not formed on the end of the inner lead surface 21B of the wire connection portion 11AA on the tip surface 24B side, and the end is in contact with the sealing resin 90.

[0339] This configuration can prevent peeling of the plating layer 29 at the end of the inner lead surface 21B of the wire connection portion 11AA near the tip surface 24B from occurring between the sealing resin 90. Note that the wire connection portions 12AA, 13AA, 15AA to 18AA of the first lead terminals 12, 13, 15 to 18 have the same configuration, and therefore the same effect can be obtained.

[0340] (1-17) A plating layer 29 is formed on the inner lead surface 21B of the wire connection portion 48AA of the second inner lead portion 48A of the second lead terminal 48. The plating layer 29 is not formed on the end of the inner lead surface 21B of the wire connection portion 48AA on the tip surface 24B side, and the end is in contact with the sealing resin 90.

[0341] This configuration can prevent peeling of the plating layer 29 at the end of the wire connection portion 48AA on the inner lead surface 21B near the tip surface 24B from occurring between the sealing resin 90. Note that the wire connection portions 42AA to 45AA, 47AA of the second lead terminals 42 to 45, 47 have a similar configuration, and therefore the same effect can be obtained.

[0342] (1-18) 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.

[0343] 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.

[0344] (1-19) 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 through the sealing resin 90 between the first lead terminals 11 to 18 and the second lead terminals 41 to 48. This improves the dielectric strength between the first lead terminals 11 to 18 and the second lead terminals 41 to 48.

[0345] 27 to 29, 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, 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.

[0346] As shown in FIG. 27 , the shape of the wire connection portion 13AA of the first lead terminal 13 of the first frame 10A, among the first lead terminals 11 to 18, is different from that of the first embodiment. More specifically, the wire connection portion 13AA extends obliquely toward the first chip 60 as it moves away from the lead connection portion 13AB and away from the first sealing side surface 93. The corner portion of the tip side of the wire connection portion 13AA that is closer to the wire connection portion 12AA of the first lead terminal 12 includes an inclined surface 13AC. The inclined surface 13AC is formed so that the distance between it and the wire connection portion 12AA in the X direction is constant. In a plan view, the inclined surface 13AC faces the wire connection portion 12AA in the X direction.

[0347] Two first lead wires WB are connected to the wire connection portion 13AA. The first lead wire WB arranged closer to the first lead terminal 12 extends from the first bond portion of the first chip 60 so as to pass through the tip surface of the wire connection portion 13AA in a plan view. The first lead wire WB that has passed through the tip surface of the wire connection portion 13AA in a plan view is then bonded to the wire connection portion 13AA. Here, the tip surface of the wire connection portion 13AA is the side surface of the wire connection portion 13AA facing the first chip 60, and extends in a direction perpendicular to the extension direction of the wire connection portion 13AA in a plan view.

[0348] The remaining first lead wire WB extends from the first bond portion of the first chip 60 so as to pass through the tip surface of the wire connection portion 13AA in a plan view. The first lead wire WB that has passed through the tip surface of the wire connection portion 13AA in a plan view is joined to a portion of the wire connection portion 13AA that is closer to the tip surface of the wire connection portion 13AA than the second bond portion of the first lead wire WB, which is arranged closer to the first lead terminal 12.

[0349] In a plan view, the two first lead wires WB extend perpendicular to the tip surface of the wire connecting portion 13AA. Here, if the angle formed between the first lead wires WB and the tip surface of the wire connecting portion 13AA is 85° or more and 95° or less, it can be said that the first lead wires WB extend perpendicular to the tip surface of the wire connecting portion 13AA.

[0350] In other words, the two first lead wires WB extend parallel to the extending direction of the wire connecting portion 13AA. Here, if the absolute value of the acute angle formed between the extending direction of the first lead wires WB and the extending direction of the wire connecting portion 13AA is between 0° and 5°, it can be said that the first lead wires WB extend parallel to the extending direction of the wire connecting portion 13AA. Note that in the second embodiment, the tip surface of the wire connecting portion 13AA corresponds to "the side surface that intersects with the first lead wires WB connected to the wire connecting portion 13AA in a plan view."

[0351] In plan view, the relationship between the first lead wire WB connected to the wire connecting portion 13AA and the tip surface of the wire connecting portion 13AA is not limited to being orthogonal. In plan view, the first lead wire WB connected to the wire connecting portion 13AA may extend so as to intersect with the tip surface of the wire connecting portion 13AA.

[0352] 27 , the shape of a portion of the first die pad 30 differs from that of the first embodiment. More specifically, an inclined surface 36A4 is formed between the first surface 36A1 of the first recessed portion 36A of the first die pad 30 and the first base end surface 32. In plan view, the inclined surface 36A4 is inclined away from the wire connection portion 13AA as it approaches the first base end surface 32. The inclined surface 36A4 is formed so that the distance between the inclined surface 36A4 and the wire connection portion 13AA in the X direction is constant. Therefore, in plan view, the inclined surface 36A4 and the tip surface of the wire connection portion 13AA are parallel to each other.

[0353] As shown in FIG. 28 , the shape of the wire connection portion 42AA of the second lead terminal 42 of the second frame 10B, among the second lead terminals 41 to 44, is different from that of the first embodiment. More specifically, the wire connection portion 42AA is inclined in a direction away from the second sealing side surface 94 as it moves from the lead connection portion 42AB toward the second chip 70. In other words, the wire connection portion 42AA extends obliquely from the lead connection portion 42AB toward the second chip 70. The corner portion of the tip side of the wire connection portion 42AA that is closer to the second chip 70 includes an inclined surface 42AC. The inclined surface 42AC is formed so that the distance between it and the second die pad 50A in the X direction is constant. In a plan view, the inclined surface 42AC faces the second die pad 50A in the X direction.

[0354] Two second lead wires WD are connected to the wire connection portion 42AA. The second lead wire WD disposed closer to the second lead terminal 43 extends from the first bond portion of the second chip 70 so as to pass through the tip surface of the wire connection portion 42AA in a plan view. The second lead wire WD that passes through the tip surface of the wire connection portion 42AA in a plan view is then joined to the wire connection portion 42AA. Here, the tip surface of the wire connection portion 42AA is the side surface of the wire connection portion 42AA facing the second chip 70, and extends in a direction perpendicular to the extension direction of the wire connection portion 42AA in a plan view.

[0355] In a plan view, the second lead wire WD extends perpendicular to the tip surface of the wire connecting portion 42AA. Here, if the angle formed between the second lead wire WD and the tip surface of the wire connecting portion 42AA is 85° or more and 95° or less, it can be said that the second lead wire WD extends perpendicular to the tip surface of the wire connecting portion 42AA.

[0356] In other words, the second lead wire WD extends parallel to the extending direction of the wire connection portion 42AA. Here, if the absolute value of the acute angle formed between the extending direction of the second lead wire WD and the extending direction of the wire connection portion 42AA is between 0° and 5°, it can be said that the second lead wire WD extends parallel to the extending direction of the wire connection portion 42AA. Note that in the second embodiment, the tip surface of the wire connection portion 42AA corresponds to "the side surface that intersects with the second lead wire WD connected to the wire connection portion 42AA in a plan view."

[0357] In plan view, the relationship between the second lead wire WD connected to the wire connection portion 42AA and the tip surface of the wire connection portion 42AA does not have to be orthogonal. In plan view, the second lead wire WD connected to the wire connection portion 42AA may extend so as to intersect with the tip surface of the wire connection portion 42AA.

[0358] Furthermore, of the two second lead wires WD connected to the second lead terminal 42, the remaining second lead wire WD extends from the first bond portion of the second chip 70 so as to pass through the inclined surface 42AC in a plan view. The first lead wire WB that passes through the tip surface of the wire connection portion 42AA in a plan view is joined to a portion of the wire connection portion 42AA that is closer to the lead connection portion 42AB than the second bond portion of the second lead wire WD that is arranged closer to the second lead terminal 43. In a plan view, the remaining second lead wire WD extends so as to intersect with the inclined surface 42AC.

[0359] In a plan view, the remaining second lead wires WD extend parallel to the extending direction of the wire connection portion 42AA. Here, if the absolute value of the acute angle formed between the extending direction of the remaining second lead wires WD and the extending direction of the wire connection portion 42AA is between 0° and 5°, it can be said that the remaining second lead wires WD extend parallel to the extending direction of the wire connection portion 42AA. Note that in the second embodiment, the inclined surface 42AC corresponds to "a side surface that intersects with the second lead wires WD connected to the wire connection portion 42AA in a plan view."

[0360] 28 , the shape of a portion of the second die pad 50A differs from that of the first embodiment. More specifically, a recess 59A is formed in the second surface 56A2 of the fourth recess 56A of the second die pad 50A. The recess 59A is formed in a portion of the second die pad 50A closer to the third sealing side surface 95 than the second chip 70. The recess 59A has a first side surface 59A1 connected to the curved recess 56A3 of the fourth recess 56A, a second side surface 59A2 connected to the second surface 56A2, and a bottom surface 59A3.

[0361] First side surface 59A1 extends obliquely toward second chip 70 as it moves from curved recess 56A3 toward bottom surface 59A3. In one example, in a plan view, the direction in which first side surface 59A1 extends is parallel to the direction in which wire connection portion 42AA extends. Here, if the absolute value of the acute angle formed between the direction in which first side surface 59A1 extends and the direction in which wire connection portion 42AA extends is between 0° and 5° in plan view, it can be said that the direction in which first side surface 59A1 extends is parallel to the direction in which wire connection portion 42AA extends.

[0362] The second side surface 59A2 extends obliquely from the second surface 56A2 toward the bottom surface 59A3 toward the third sealing side surface 95. The second side surface 59A2 includes a portion facing the tip surface of the wire connection portion 42AA. In one example, in a plan view, the extension direction of the second side surface 59A2 is parallel to the extension direction of the tip surface of the wire connection portion 42AA. Here, if the absolute value of the acute angle formed between the extension direction of the second side surface 59A2 and the extension direction of the tip surface of the wire connection portion 42AA in a plan view is between 0° and 5°, it can be said that the extension direction of the second side surface 59A2 is parallel to the extension direction of the tip surface of the wire connection portion 42AA.

[0363] The bottom surface 59A3 is formed between the first side surface 59A1 and the second side surface 59A2 in the Y direction. The bottom surface 59A3 extends along the Y direction in a plan view. The bottom surface 59A3 faces the inclined surface 42AC in the X direction.

[0364] As shown in FIG. 29 , the shape of the wire connection portion 47AA of the second lead terminal 47 of the second frame 10B, among the second lead terminals 45 to 48, is different from that of the first embodiment. More specifically, the wire connection portion 47AA includes a portion whose width (size in the X direction) is larger than the width (size in the X direction) of the wire connection portion 47AA of the first embodiment. A corner portion of the tip side of the wire connection portion 47AA, closer to the second sealing side surface 94, includes an inclined surface 47AC1. The inclined surface 47AC1 extends obliquely toward the fourth sealing side surface 96 as it approaches the second sealing side surface 94. The portion of the wire connection portion 47AA closer to the lead connection portion 47AB includes an inclined surface 47AC2. The inclined surface 47AC2 extends obliquely toward the fourth sealing side surface 96 as it approaches the second sealing side surface 94. In one example, the extending direction of the inclined surface 47AC1 and the extending direction of the inclined surface 47AC2 are parallel in a plan view.

[0365] Two second lead wires WD are connected to the wire connection portion 47AA. In a plan view, the two second lead wires WD extend from the first bond portion of the second chip 70 so as to pass through the side surface 47AA1 of the wire connection portion 42AA. The two second lead wires WD that pass through the side surface 47AA1 of the wire connection portion 47AA in a plan view are then bonded to the wire connection portion 47AA. Here, the side surface 47AA1 of the wire connection portion 47AA is the side surface of the wire connection portion 47AA facing away from the second sealing side surface 94 and extends in the Y direction in a plan view. In a plan view, the second lead wires WD extend so as to intersect with the side surface 47AA1 of the wire connection portion 47AA. Note that, in a plan view, the second lead wires WD may extend so as to be perpendicular to the side surface 47AA1 of the wire connection portion 47AA.

[0366] Furthermore, the second lead wire WD extends parallel to the direction in which the inclined surfaces 47AC1 and 47AC2 extend in a plan view. Here, if the absolute value of the acute angle formed between the direction in which the second lead wire WD extends and the direction in which the inclined surfaces 47AC1 and 47AC2 extend is between 0° and 5°, it can be said that the second lead wire WD extends parallel to the direction in which the inclined surfaces 47AC1 and 47AC2 extend. In the second embodiment, the side surface 47AA1 of the wire connection portion 47AA corresponds to "the side surface that intersects with the second lead wire WD connected to the wire connection portion 47AA in a plan view."

[0367] As shown in Figure 29, the shape of a portion of the third die pad 50B differs from that of the first embodiment. More specifically, the position of the second surface 57D2 of the seventh recessed portion 57D in the X direction is farther from the second sealing side surface 94 than the second surface 48AC2 of the recessed portion 48AC of the wire connection portion 48AA of the second lead terminal 48. Furthermore, an inclined surface 57D4 is formed between the first surface 57D1 and the second surface 57D2 of the seventh recessed portion 57D instead of the curved recess 57D3 (see Figure 13). The inclined surface 57D4 is inclined so as to approach the fourth sealing side surface 96 as it moves away from the second sealing side surface 94.

[0368] [Effects] The signal transmission device 10 of the second embodiment has the following effects: (2-1) The wire connection portion 13AA of the first lead terminal 13 includes a tip surface that intersects with the first lead wire WB connected to the wire connection portion 13AA in a plan view. The tip surface of the wire connection portion 13AA faces the first die pad 30.

[0369] With this configuration, the first lead wire WB extends in roughly the same direction as the wire connection portion 13AA in a plan view, so that the first lead wire WB can be bonded while preventing it from shifting relative to the wire connection portion 13AA. This prevents a portion of the bonded portion of the first lead wire WB from coming off the wire connection portion 13AA. Therefore, the first lead wire WB can be stably bonded to the wire connection portion 13AA.

[0370] (2-2) The wire connection portion 42AA of the second lead terminal 42 includes a tip end surface that intersects with the second lead wire WD connected to the wire connection portion 42AA in a plan view. The tip end surface of the wire connection portion 42AA faces the second die pad 50A.

[0371] With this configuration, the second lead wire WD extends in roughly the same direction as the wire connection portion 42AA in a plan view, so the second lead wire WD can be bonded while preventing it from shifting relative to the wire connection portion 42AA. This prevents a portion of the bonded portion of the second lead wire WD from coming off the wire connection portion 42AA. Therefore, the second lead wire WD can be stably bonded to the wire connection portion 42AA.

[0372] (2-3) In a plan view, the first lead wire WB connected to the wire connection portion 13AA is perpendicular to the tip surface of the wire connection portion 13AA. With this configuration, it is easier to confirm the joining position of the first lead wire WB with the wire connection portion 13AA compared to when the first lead wire WB extends along the side surface of the wire connection portion 13AA.

[0373] (2-4) In a plan view, the first lead wire WB connected to the wire connection portion 42AA is perpendicular to the tip surface of the wire connection portion 42AA. With this configuration, it is easier to confirm the joining position of the first lead wire WB with the wire connection portion 42AA compared to when the first lead wire WB extends along the side surface of the wire connection portion 42AA.

[0374] (2-5) The wire connection portion 13AA of the first lead terminal 13 includes an inclined surface 13AC. With this configuration, the inclined surface 13AC forms a corner of the portion of the wire connection portion 13AA near the tip end surface, with the corner notched. This allows a large distance in the X direction between the wire connection portion 13AA and the wire connection portion 12AA of the first lead terminal 12.

[0375] (2-6) The first die pad 30 includes an inclined surface 36A4. With this configuration, the inclined surface 36A4 can increase the distance between the wire connection portion 13AA and the first die pad 30 in the Y direction.

[0376] (2-7) The wire connection portion 42AA of the second lead terminal 42 includes an inclined surface 42AC. With this configuration, the inclined surface 42AC forms a corner of the portion of the wire connection portion 42AA near the tip end surface, which is cut out. This allows for a large distance in the X direction between the wire connection portion 42AA and the second die pad 50A.

[0377] (2-8) The second die pad 50A includes a recess 59A. With this configuration, the recess 59A can increase the distance between the wire connection portion 42AA and the second die pad 50A in the X direction.

[0378] 30 to 33, 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.

[0379] The first frame 10A of the third embodiment differs in the configuration of the first lead terminals 13, 15, and 16 among the first lead terminals 11 to 18. More specifically, as shown in FIGS. 30 and 31 , the first inner lead portions 13A, 15A, and 16A of the first lead terminals 13, 15, and 16 have through holes 13AD, 15AD, and 16AD formed therein, penetrating the first inner lead portions 13A, 15A, and 16A in their thickness direction (Z direction). In one example, the through holes 13AD, 15AD, and 16AD are circular in plan view. In the third embodiment, the through holes 13AD, 15AD, and 16AD have the same diameter. The diameters of the through holes 13AD, 15AD, and 16AD are smaller than the diameters of the through holes 11AD, 12AD, 17AD, and 18AD. The shape and size of each of the through holes 12AD to 17AD in plan view can be changed arbitrarily.

[0380] The through holes 13AD, 15AD, and 16AD are filled with sealing resin 90. That is, the sealing resin 90 filled in the through holes 13AD, 15AD, and 16AD connects the sealing resin 90 provided closer to a sealing surface 91 (see FIG. 2) than the first inner lead portions 13A, 15A, and 16A with the sealing resin 90 provided closer to a sealing back surface 92 (see FIG. 2) than the first inner lead portions 13A, 15A, and 16A.

[0381] Here, first lead terminal 14 is integrated with first die pad 30 and therefore corresponds to a "first connection terminal." First lead terminals 11 to 13 and 15 to 18 are disposed apart from first die pad 30 and therefore correspond to "first remote terminals." Because through holes 11AD to 13AD and 15AD to 18AD are formed in first lead terminals 11 to 13 and 15 to 18, it can be said that the first remote terminals have through holes that penetrate the first remote terminals in the thickness direction. On the other hand, the first connection terminals do not have through holes.

[0382] 30 , 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 disposed spaced apart from the through hole 13AD in the Y direction in plan view.

[0383] 31 , 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. The through hole 15AD is formed across the wire connection portion 15AA and the lead connection portion 15AB.

[0384] 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 disposed spaced apart from the through hole 16AD in the Y direction in a plan view.

[0385] The positions of the through holes 13AD, 15AD, and 16AD can be changed as desired. For example, the through holes 13AD, 15AD, and 16AD may be formed in the lead connection portions 13AB, 15AB, and 16AB. The through holes 13AD and 16AD may also be formed across the wire connection portions 13AA and 16AA and the lead connection portions 13AB and 16AB. The through hole 15AD may be formed in a portion of the wire connection portion 15AA that is closer to the first lead terminal 14 than the lead connection portion 15AB.

[0386] As shown in FIGS. 32 and 33 , the second frame 10B of the third embodiment differs in the configuration of the second lead terminals 42 to 45, 47 among the second lead terminals 41 to 48. More specifically, the second inner lead portions 42A to 45A, 47A of the second lead terminals 42 to 45, 47 are formed with through holes 42AD to 45AD, 47AD that penetrate the second inner lead portions 42A to 45A, 47A in their thickness direction (Z direction). In one example, the through holes 42AD to 45AD, 47AD are circular in plan view. In the third embodiment, the through holes 42AD to 45AD, 47AD have the same diameter. The diameters of the through holes 42AD to 45AD, 47AD are smaller than the diameter of the through hole 48AD. The diameters of the through holes 42AD to 45AD and 47AD are equal to the diameters of the through holes 13AD, 15AD and 16AD. The shapes and sizes of the through holes 42AD to 45AD and 47AD in plan view can be changed as desired.

[0387] The through holes 42AD to 45AD, 47AD are filled with sealing resin 90. In other words, the sealing resin 90 filled in the through holes 42AD to 45AD, 47AD connects the sealing resin 90 provided closer to the sealing surface 91 (see FIG. 2) than the second inner lead portions 42A to 45A, 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 45A, 47A.

[0388] Here, the second lead terminal 41 is integrated with the second die pad 50A and corresponds to a "second connection terminal." The second lead terminals 42 to 44 are disposed spaced apart from the second die pad 50A and correspond to "second remote terminals." Because the through holes 42AD to 44AD are formed in the second lead terminals 42 to 44, the second remote terminals can be said to have through holes that penetrate the second remote terminals in the thickness direction.

[0389] The second lead terminal 46 is integrated with the third die pad 50B and corresponds to the "third connection terminal." The second lead terminals 45 to 48 are disposed spaced apart from the third die pad 50B and correspond to the "third remote terminals." Because the through holes 45AD, 47AD, and 48AD are formed in the second lead terminals 45, 47, and 48, the third remote terminals can be said to have through holes that penetrate the third remote terminals in the thickness direction. On the other hand, the second lead terminal 46 does not have a through hole.

[0390] 32 , 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 joined 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 arranged spaced apart from the through hole 42AD in the Y direction in a plan view.

[0391] 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 Y direction in a plan view.

[0392] 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 through hole 44AD is formed at a position that overlaps with the lead connection portion 44AB when viewed from the X direction.

[0393] 33, 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 through hole 45AD is formed at a position that overlaps with the lead connection portion 45AB when viewed from the X direction.

[0394] 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. Each of the two second lead wires 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. Each of the second bond portions of the two second lead wires WD is disposed spaced apart from the through hole 47AD in the Y direction in plan view.

[0395] The positions where the through holes 42AD to 45AD and 47AD are formed can be changed as desired. For example, the through holes 42AD to 45AD and 47AD may be formed in the lead connection portions 42AB to 45AB and 47AB. Furthermore, the through holes 42AD to 45AB and 47AD may be formed across the wire connection portions 42AA to 45AA and 47AA and the lead connection portions 42AB to 45AB and 47AB.

[0396] [Effects] The signal transmission device 10 of the third embodiment has the following effects: (3-1) The first lead terminals 11 to 13 and 15 to 18 have through holes 11AD to 13AD and 15AD to 18AD. The through holes 11AD to 13AD and 15AD to 18AD are filled with sealing resin 90.

[0397] According to this configuration, the sealing resin 90 filled in the through holes 11AD-13AD, 15AD-18AD can prevent the first lead terminals 11-13, 15-18 from moving when an external force is applied to the first lead terminals 11-13, 15-18. Therefore, when the first lead wires WB are joined to each of the first lead terminals 11-13, 15-18, it is possible to prevent force from being applied to the first lead wires WB due to movement of the first lead terminals 11-13, 15-18.

[0398] (3-2) The second lead terminals 42 to 45, 47, and 48 have through holes 42AD to 45AD, 47AD, and 48AD. The through holes 42AD to 45AD, 47AD, and 48AD are filled with a sealing resin 90.

[0399] According to this configuration, the sealing resin 90 filled in the through holes 42AD to 45AD, 47AD, and 48AD can prevent the second lead terminals 42 to 45, 47, and 48 from moving when an external force is applied to the second lead terminals 42 to 45, 47, and 48. Therefore, when the second lead wires WD are joined to each of the second lead terminals 42 to 45, 47, and 48, 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 45, 47, and 48.

[0400] 34 to 37, 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.

[0401] The first frame 10A of the fourth embodiment is different from the third embodiment in the configuration of the first lead terminals 13, 15, and 16 among the first lead terminals 11 to 18. More specifically, as shown in Figures 34 and 35, through holes 13AD, 15AD, and 16AD (see Figures 30 and 31) are omitted from the first inner lead portions 13A, 15A, and 16A of the first lead terminals 13, 15, and 16.

[0402] In other words, the first frame 10A includes two types of first lead terminals: first specific terminals (first lead terminals 11, 12, 17, 18 in the fourth embodiment) having through holes formed therein among the first inner lead portions 11A to 13A, 15A to 18A of the first lead terminals 11 to 13, 15 to 18; and second specific terminals (first lead terminals 13, 15, 16 in the fourth embodiment) having no through holes formed therein.

[0403] 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 on the second bond portion of the first lead wire WB connected to the wire connection portions 13AA, 15AA, and 16AA of the first inner lead portions 13A, 15A, and 16A of the first lead terminals 13, 15, and 16 serving as the second specified terminals. On the other hand, no security bond WB1 is formed on the second bond portion of the first lead wire WB connected to the wire connection portions 11AA, 12AA, and 18AA of the first inner lead portions 11A, 12A, and 18A of the first lead terminals 11, 12, and 18 serving as the first specified terminals.

[0404] That is, the plurality of first lead wires WB include first specified wires joined to first specified terminals (first lead terminals 11, 12, and 18 in the fourth embodiment) and second specified wires joined to second specified terminals (first lead terminals 13, 15, and 16 in the fourth embodiment). A security bond is formed at a joint (second bond portion) of the second specified wire joined to the second specified terminal.

[0405] The second frame 10B of the fourth embodiment is different from the third embodiment in the configuration of the second lead terminals 43 and 47 among the second lead terminals 42 to 45, 47, and 48. More specifically, as shown in FIGS. 36 and 37 , the through holes 43AD and 47AD are omitted from the second inner lead portions 43A and 47A of the second lead terminals 43 and 47. In other words, the second frame 10B includes two types of second lead terminals: second lead terminals having through holes (second lead terminals 42, 44, 45, and 48 in the fourth embodiment) among the second lead terminals 42 to 45, 47, and 48, and second lead terminals not having through holes (second lead terminals 43 and 47 in the fourth embodiment).

[0406] In other words, the second frame 10B includes two types of second lead terminals: third specific terminals (second lead terminals 42, 44, 45, 48 in the fourth embodiment) having through holes formed therein among the second inner lead portions 42A to 45A, 47A, 48A of the second lead terminals 42 to 45, 47, 48; and fourth specific terminals (second lead terminals 43, 47 in the fourth embodiment) having no through holes formed therein.

[0407] 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 portion 43AA, 47AA of the second inner lead portion 43A, 47A of the second lead terminal 43, 47 serving as the fourth specified terminal. 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 portion 42AA, 48AA of the second inner lead portion 42A, 48A of the second lead terminal 42, 48 serving as the third specified terminal.

[0408] That is, the multiple second lead wires WD include a third specified wire joined to a third specified terminal (the second lead terminals 42 and 48 in the fourth embodiment) and a fourth specified wire joined to a fourth specified terminal (the second lead terminals 43 and 47 in the fourth embodiment). A security bond is formed at the bond portion (second bond portion) of the fourth specified wire joined to the fourth specified terminal. The security bonds WB1 and WD1 have the same configuration as, for example, the security bond WF1 in the first embodiment (see FIG. 15). Note that the through holes 44AD and 45AD may be omitted from at least one of the second lead terminals 44 and 45.

[0409] [Effects] The signal transmission device 10 of the fourth embodiment has the following effects: (4-1) Of the first lead terminals 11 to 13 and 15 to 18, the first lead terminals 13, 15, and 16 do not have through holes 13AD, 15AD, and 16AD. A security bond WB1 is formed in the second bond portion of the first lead wire WB joined to the wire connection portions 13AA, 15AA, and 16AA of the first lead terminals 13, 15, and 16.

[0410] With this configuration, even if an external force is applied to the first lead terminals 13, 15, 16 and the first lead terminals 13, 15, 16 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 13AA, 15AA, 16AA.

[0411] (4-2) Through holes 11AD, 12AD, 17AD, and 18AD are formed in the first lead terminals 11, 12, 17, and 18 of the first lead terminals 11 to 13 and 15 to 18. No security bond is formed in the second bond portion of the first lead wire WB joined to the wire connection portions 11AA, 12AA, and 18AA of the first lead terminals 11, 12, and 18.

[0412] According to this configuration, the sealing resin 90 filled in the through holes 11AD, 12AD, 17AD, and 18AD suppresses movement of the first lead terminals 11, 12, 17, and 18. This reduces the amount of force applied to the first lead wires WB joined to the first lead terminals 11, 12, and 18. Furthermore, since there is no need to form security bonds on the first lead wires WB joined to the first lead terminals 11, 12, and 18, the manufacturing process can be simplified. This allows for a reduction in the manufacturing cost of the signal transmission device 10.

[0413] (4-3) Of the second lead terminals 42 to 45, 47, and 48, the second lead terminals 43 and 47 do not have through holes 43AD and 47AD. A security bond WD1 is formed in the second bond portion of the second lead wire WD joined to the wire connection portions 43AA and 47AA of the second lead terminals 43 and 47.

[0414] According to this configuration, even if an external force is applied to the second lead terminals 43, 47 and the second lead terminals 43, 47 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 43AA, 47AA.

[0415] (4-4) Through holes 42AD, 44AD, 45AD, and 48AD are formed in the second lead terminals 42, 44, 45, and 48 among the second lead terminals 42 to 45 and 48. No security bond is formed in the second bond portion of the second lead wire WD joined to the second lead terminals 42 and 48.

[0416] According to this configuration, the sealing resin 90 filled in the through holes 42AD, 44AD, 45AD, and 48AD suppresses movement of the second lead terminals 42, 44, 45, and 48. This reduces the amount of force applied to the second lead wires WD joined to the second lead terminals 42 and 48. Furthermore, since there is no need to form security bonds on the second lead wires WD joined to the second lead terminals 42 and 48, the manufacturing process can be simplified. This allows for a reduction in the manufacturing cost of the signal transmission device 10.

[0417] Fifth Embodiment A signal transmission device 10 of a fifth embodiment will be described with reference to Fig. 38. 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.

[0418] 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 third die pad 50B. More specifically, the arc length of the second tip curved surface 35B of the first die pad 30 of the fifth embodiment is longer than that of the first embodiment. The arc length of the second tip curved surface 55BB of the third die pad 50B of the fifth embodiment is longer than that of the first embodiment.

[0419] In a plan view, the arc length of the second tip curved surface 35B is longer than the arc length of the first tip curved surface 35A (see FIG. 7 ). In a plan view, the arc length of the second tip curved surface 35B is longer than the arc length of the first tip curved surface 55BA of the third die pad 50B. In addition, in a plan view, it can be said that the radius of curvature of the second tip curved surface 35B is larger than the radius of curvature of the first tip curved surface 35A. In a plan view, it can be said that the radius of curvature of the second tip curved surface 35B is larger than the radius of curvature of the first tip curved surface 55BA of the third die pad 50B.

[0420] In one example, in a plan view, the arc length of second tip curved surface 35B is at least twice the arc length of first tip curved surface 35A. In one example, in a plan view, the arc length of second tip curved surface 35B is at least twice the arc length of first tip curved surface 55BA of third die pad 50B.

[0421] In a plan view, the arc length of the second tip curved surface 55BB of the third die pad 50B is longer than the arc length of the first tip curved surface 55BA, and the radius of curvature of the second tip curved surface 55BB is greater than the radius of curvature of the first tip curved surface 55BA.

[0422] In one example, in a plan view, the arc length of second tip curved surface 55BB is at least twice the arc length of first tip curved surface 55BA. In one example, in a plan view, the arc length of second tip curved surface 55BB is equal to the arc length of second tip curved surface 35B of first die pad 30.

[0423] The arc length of the second tip curved surface 35B of the first die pad 30 and the arc length of the second tip curved surface 55BB of the third die pad 50B in plan view can each be changed as desired. In one example, the arc length of the second tip curved surface 35B in plan view may be longer than the arc length of the second tip curved surface 55BB.

[0424] [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 surface 31 and the first side surface 33, and a second tip-side curved surface 35B formed between the first tip surface 31 and the second side surface 34. In a plan view, the arc length of the second tip-side curved surface 35B is longer than the arc length of the first tip-side curved surface 35A.

[0425] According to this configuration, the second tip-side curved surface 35B can alleviate electric field concentration at the corner portion at the tip of the first die pad 30 that is close to the third die pad 50B. This makes it possible to avoid dielectric breakdown between the first die pad 30 and the third die pad 50B, thereby improving the dielectric strength of the signal transmission device 10.

[0426] (5-2) The third die pad 50B has a first tip curved surface 55BA formed between the die pad facing surface 51B and the fifth side surface 53B, and a second tip curved surface 55BB formed between the die pad facing surface 51B and the sixth side surface 54B. In a plan view, the arc length of the second tip curved surface 55BB is longer than the arc length of the first tip curved surface 55BA.

[0427] According to this configuration, the second tip-side curved surface 55BB can alleviate electric field concentration at the corner portion at the tip of the third die pad 50B 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 third die pad 50B, thereby improving the dielectric strength voltage of the signal transmission device 10.

[0428] 39 to 48, a signal transmission device 10 according to a sixth embodiment will be described. The signal transmission device 10 according to the sixth embodiment differs from the signal transmission device 10 according to the first embodiment mainly in the configuration of each of the first chip 60, the second chip 70, and the third chip 80. 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.

[0429] Fig. 39 shows a schematic cross-sectional structure of the first die pad 30 and the first chip 60 taken along the XZ plane, and Fig. 40 shows a schematic cross-sectional structure of the first die pad 30 and the first chip 60 taken along the YZ plane. For this reason, the wires WA to WC and the sealing resin 90 are omitted from the cross-sectional structures in Figs. 39 and 40.

[0430] 39 and 40 , 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.

[0431] 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. 39 and 40 , the step portion 139 is formed around the entire periphery of the substrate 130.

[0432] 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.

[0433] 39 and 40 , 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. 39 and 40 , the first fillet SDA is formed over the entire first portion 137 in the Z direction.

[0434] 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.

[0435] 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.

[0436] 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.

[0437] Fig. 41 shows a schematic cross-sectional structure of second die pad 50A and second chip 70 taken along the XZ plane, and Fig. 42 shows a schematic cross-sectional structure of second die pad 50A and second chip 70 taken along the YZ plane. For this reason, wires WD, WE and sealing resin 90 are omitted from the cross-sectional structures of Fig. 41 and Fig. 42.

[0438] 41 and 42 , the second chip 70 mounted on the second die pad 50A 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.

[0439] The wide bandgap semiconductor is a semiconductor substrate having a bandgap of 2.0 eV or greater. The wide bandgap semiconductor may be any one of silicon carbide, gallium nitride, and gallium oxide. 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.

[0440] 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.

[0441] 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 50A. The second portion 238 is a portion that is provided on the first portion 237. As shown in FIGS. 41 and 42 , the step portion 239 is formed around the entire periphery of the substrate 230.

[0442] 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.

[0443] 41 and 42 , the second conductive bonding material SD2 is interposed between the first portion 237 and the second die pad 50A 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. 41 and 42 , the second fillet SDB is formed over the entire first portion 237 in the Z direction.

[0444] 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.

[0445] 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.

[0446] 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.

[0447] Fig. 43 shows a schematic cross-sectional structure of the third die pad 50B and the third chip 80 taken along the XZ plane, and Fig. 44 shows a schematic cross-sectional structure of the third die pad 50B and the third chip 80 taken along the YZ plane. For this reason, the wires WD, WF and the sealing resin 90 are omitted from the cross-sectional structures of Fig. 43 and Fig. 44.

[0448] As shown in Figures 43 and 44, the third chip 80 mounted on the third die pad 50B includes a substrate 330. The substrate 330 is formed, for example, of a semiconductor substrate. The substrate 330 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 330. 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 330.

[0449] The wide bandgap semiconductor is a semiconductor substrate having a bandgap of 2.0 eV or greater. The wide bandgap semiconductor may be any one of silicon carbide, gallium nitride, and gallium oxide. 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.

[0450] Substrate 330 of third chip 80 has first to fourth substrate side surfaces 333 to 336 connecting substrate front surface 331 and substrate back surface 332. First substrate side surface 333 constitutes a part of first chip side surface 83 of third chip 80, second substrate side surface 334 constitutes a part of second chip side surface 84, third substrate side surface 335 constitutes a part of third chip side surface 85, and fourth substrate side surface 336 constitutes a part of fourth chip side surface 86.

[0451] The substrate 330 can be divided into a first portion 337 and a second portion 338 by a step portion 339. The first portion 337 is a portion of the substrate 330 that is closer to the third die pad 50B. The second portion 338 is a portion that is provided on the first portion 337. As shown in FIGS. 43 and 44 , the step portion 339 is formed around the entire periphery of the substrate 330.

[0452] In one example, the thickness dimension (size in the Z direction) of the first portion 337 is larger than the thickness dimension (size in the Z direction) of the second portion 338. In one example, the thickness dimension of the first portion 337 is more than twice the thickness dimension of the second portion 338. In one example, the thickness dimension of the first portion 337 is more than three times the thickness dimension of the second portion 338. In one example, the thickness dimension of the first portion 337 is less than four times the thickness dimension of the second portion 338.

[0453] 43 and 44 , the third conductive bonding material SD3 is interposed between the first portion 337 and the third die pad 50B in the Z direction, and has a portion that protrudes from the third chip 80 in a direction perpendicular to the Z direction. This protruding portion forms a third fillet SDC between the first portion 337 and the third conductive bonding material SD3. The third fillet SDC is not formed in the second portion 338 due to a step portion 339. In the example shown in FIGS. 43 and 44 , the third fillet SDC is formed over the entire first portion 337 in the Z direction.

[0454] The height dimension (size in the Z direction) of the third fillet SDC can be changed as desired as long as it is lower than the step portion 339. In one example, the height dimension of the third fillet SDC may be approximately half the thickness dimension of the first portion 337.

[0455] Furthermore, the position of the step portion 339 in the third chip 80 in the Z direction can be changed as desired. That is, the relationship between the thickness of the first portion 337 and the thickness of the second portion 338 can be changed as desired. In one example, the thickness of the first portion 337 may be equal to the thickness of the second portion 338. In one example, the thickness of the first portion 337 is ½ or less of the thickness of the second portion 338. In one example, the thickness of the first portion 337 is ⅓ or less of the thickness of the second portion 338. In one example, the thickness of the first portion 337 is ¼ or more of the thickness of the second portion 338. In one example, the thickness of the first portion 337 is ¼ or more and ¾ or less of the thickness (size in the Z direction) of the third chip 80.

[0456] The width H3 of the step portion 339 is equal to each other on the first to fourth substrate side surfaces 333 to 336. The width H3 of the step portion 339 is, for example, about 3 μm. Here, the width H3 of the step portion 339 can be defined, for example, by the distance between a portion of the first substrate side surface 333 corresponding to the first portion 337 and a portion of the first substrate side surface 333 corresponding to the second portion 338.

[0457] As described above, the Z-direction positions of step portions 139, 239, and 339 are determined individually for the first chip 60, the second chip 70, and the third chip 80, so the distance in the Z-direction between the first die pad 30 and step portion 139, the distance in the Z-direction between the second die pad 50A and step portion 239, and the distance in the Z-direction between the third die pad 50B and step portion 339 may differ from one another.

[0458] Additionally, the ratio of the thickness dimension of the second portion 138 to the thickness dimension of the first portion 137 of the first chip 60, the ratio of the thickness dimension of the second portion 238 to the thickness dimension of the first portion 237 of the second chip 70, and the ratio of the thickness dimension of the second portion 338 to the thickness dimension of the first portion 337 of the third chip 80 may be different. In one example, the ratio of the thickness dimension of the second portion 138 to the thickness dimension of the first portion 137 of the first chip 60 may be 1 / 3, and the ratio of the thickness dimension of the second portion 238 to the thickness dimension of the first portion 237 of the second chip 70 and the ratio of the thickness dimension of the second portion 338 to the thickness dimension of the first portion 337 of the third chip 80 may both be 1.

[0459] [Method for Manufacturing First Chip] An example of a manufacturing process for the first chip 60 will be described with reference to FIGS. 45 to 48 . 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. 45 to 48 show a schematic cross-sectional structure of the first chip 60. In FIGS. 46 to 48 , 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 and the third chip 80 are manufactured in the same manner as the first chip 60, an example of a manufacturing process for the second chip 70 and the third chip 80 will not be described here.

[0460] 45, in the step of preparing a substrate 830, a substrate 830 including a plurality of substrates 130 (see FIG. 39) is prepared. Here, in regions of the substrate 830 corresponding to each of the plurality of substrates 130, the first transmission unit 501, the second transmission unit 502, the logic unit 503, the LDO unit 504, the UVLO unit 505, the delay unit 506, the Schmitt triggers 507 and 508, and the resistors 509 and 510 shown in FIG. 16 are formed.

[0461] As shown in FIG. 46, in the process of forming an element insulating layer 850 on a substrate 830, SiO 2 is formed 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.

[0462] 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.

[0463] 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.

[0464] 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.

[0465] 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.

[0466] 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.

[0467] 47 and 48 , the singulation process includes a first dicing process and a second dicing process. As shown in FIG. 47 , 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.

[0468] 48, 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.

[0469] [Effects] The signal transmission device 10 of the sixth embodiment has the following effects: (6-1) 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.

[0470] 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.

[0471] (6-2) 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.

[0472] According to this configuration, when the second chip 70 is mounted on the second die pad 50A 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.

[0473] (6-3) The substrate 330 of the third chip 80 has a first portion 337 including the back surface 332 of the substrate, a second portion 338 provided on the first portion 337, and a step portion 339 formed so that the second portion 338 is positioned inside the substrate 330 relative to the first portion 337.

[0474] According to this configuration, when the third chip 80 is mounted on the third die pad 50B using the third conductive bonding material SD3, the step portion 339 can prevent the third conductive bonding material SD3 from creeping up to the chip surface 81 of the third chip 80.

[0475] Seventh Embodiment A signal transmission device 10 of a seventh embodiment will be described with reference to Fig. 49. The signal transmission device 10 of the seventh 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.

[0476] 49 , 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 made only of the resin material that constitutes the sealing resin 90.

[0477] 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.

[0478] [Effects] The signal transmission device 10 of the seventh embodiment has the following effects: (7-1) 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.

[0479] 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.

[0480] Eighth Embodiment A signal transmission device 10 of an eighth embodiment will be described with reference to Fig. 50. The signal transmission device 10 of the eighth embodiment differs from the signal transmission device 10 of the first embodiment mainly in the configuration of the second frame 10B. Below, differences in the configuration of the second frame 10B from the first embodiment will be described in detail. Furthermore, components common to the first embodiment will be assigned the same reference numerals, and descriptions thereof will be omitted.

[0481] 50, the second frame 10B does not include second lead terminals 44, 45. In other words, the second frame 10B includes second lead terminals 41 to 43, 46 to 48. This increases the distance in the Y direction between the second outer lead portion 43B of the second lead terminal 43 and the second outer lead portion 46B of the second lead terminal 46. In other words, the distance in the Y direction between the second outer lead portion 43B of the second lead terminal 43 electrically connected to the second chip 70 and the second outer lead portion 46B of the second lead terminal 46 electrically connected to the third chip 80 increases.

[0482] As described above, the second frame 10B includes a plurality of second lead terminals 41 to 43 electrically connected to the second chip 70 and a plurality of second lead terminals 46 to 48 electrically connected to the third chip 80. The distance in the Y direction between the second outer lead portion 43B of the second lead terminal 43 that is closest to the second lead terminals 46 to 48 electrically connected to the third chip 80 among the second lead terminals 41 to 43 electrically connected to the second chip 70 and the second outer lead portion 46B of the second lead terminal 46 that is closest to the second lead terminals 41 to 43 electrically connected to the second chip 70 among the second lead terminals 46 to 48 electrically connected to the third chip 80 is greater than the distance between the second outer lead portions of the second lead terminals 41 to 43 electrically connected to the second chip 70 that are adjacent to each other in the Y direction.

[0483] Furthermore, the distance in the Y direction between the second outer lead portion 43B of the second lead terminal 43 that is closest to the second lead terminals 46-48 electrically connected to the third chip 80 among the second lead terminals 41-43 electrically connected to the second chip 70, and the second outer lead portion 46B of the second lead terminal 46 that is closest to the second lead terminals 41-43 electrically connected to the second chip 70 among the second lead terminals 46-48 electrically connected to the third chip 80, is greater than the distance between the second outer lead portions of adjacent second lead terminals in the Y direction among the second lead terminals 46-48 electrically connected to the third chip 80.

[0484] [Effects] The signal transmission device 10 of the eighth embodiment has the following effects: (8-1) As the shortest distance between the plurality of second lead terminals 41 to 43 electrically connected to the second chip 70 and the plurality of second lead terminals 46 to 48 electrically connected to the third chip 80, the distance between the second lead terminal 43 and the second lead terminal 46 in the Y direction is greater than the distance between the second lead terminal 41 and the second lead terminal 42 that are adjacent in the Y direction among the plurality of second lead terminals 41 to 43 electrically connected to the second chip 70.

[0485] This configuration allows a large creepage distance to be secured between the second lead terminal electrically connected to the second chip 70 and the second lead terminal electrically connected to the third chip 80. Therefore, the dielectric strength between the second chip 70 and the third chip 80 can be improved.

[0486] Ninth Embodiment A signal transmission device 10 of the ninth embodiment will be described with reference to Figures 51 and 52. The signal transmission device 10 of the ninth 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. Below, differences in the configuration of the first frame 10A and the second frame 10B from the first embodiment will be described in detail. Furthermore, components common to the first embodiment will be assigned the same reference numerals, and descriptions thereof will be omitted.

[0487] 51 , in the ninth embodiment, the connection portion 39 is omitted from the first die pad 30. Also, the shape of the first inner lead portion 14A of the first lead terminal 14 is different from that of the first embodiment. More specifically, the first inner lead portion 14A includes a first outer lead connection portion 14AB1 and a first die pad connection portion 14AB2.

[0488] The first outer lead connection portion 14AB1 is a portion that connects to the first outer lead portion 14B and extends along the X direction. As in the first embodiment, the first outer lead portion 14B is disposed offset in the Y direction toward the third sealing side surface 95 with respect to the center of gravity G1 of the first die pad 30. Therefore, the first outer lead connection portion 14AB1 is disposed offset in the Y direction toward the fourth sealing side surface 96 with respect to the first die pad 30.

[0489] The first die pad connection portion 14AB2 is a portion that connects the first outer lead connection portion 14AB1 and the first die pad 30. The first die pad connection portion 14AB2 is connected to one of the four corner portions of the first die pad 30 that is closer to the first sealing side surface 93 and the third sealing side surface 95. The first die pad connection portion 14AB2 extends obliquely in a straight line from the first sealing side surface 93 toward the second sealing side surface 94 and from the fourth sealing side surface 96 toward the third sealing side surface 95. More specifically, in plan view, as indicated by the arrows in the first die pad connection portion 14AB2 in FIG. 51 , the extension direction of the first die pad connection portion 14AB2 is toward the center of gravity G1 of the first die pad 30 in FIG. 51 . In other words, in plan view, the first die pad connection portion 14AB2 extends toward the center of gravity G1 of the first die pad 30.

[0490] 52 , in the ninth embodiment, the connection portion 59B is omitted from the third die pad 50B. Also, the shape of the second inner lead portion 46A of the second lead terminal 46 is different from that in the first embodiment. More specifically, the second inner lead portion 46A includes a second outer lead connection portion 46AB1 and a second die pad connection portion 46AB2.

[0491] The second outer lead connection portion 46AB1 is a portion that connects to the second outer lead portion 46B and extends along the X direction. As in the first embodiment, the second outer lead portion 46B is disposed offset in the Y direction toward the fourth sealing side surface 96 with respect to the center of gravity G2 of the third die pad 50B. Therefore, the second outer lead connection portion 46AB1 is disposed offset in the Y direction toward the fourth sealing side surface 96 with respect to the third die pad 50B.

[0492] The second die pad connection portion 46AB2 connects the second outer lead connection portion 46AB1 and the third die pad 50B. The second die pad connection portion 46AB2 is connected to one of the four corner portions of the third die pad 50B that is closer to the second sealing side surface 94 and the fourth sealing side surface 96. The second die pad connection portion 46AB2 extends obliquely in a straight line from the second sealing side surface 94 toward the first sealing side surface 93 and from the fourth sealing side surface 96 toward the third sealing side surface 95. More specifically, in plan view, as indicated by the arrows on the second die pad connection portion 46AB2 in FIG. 52 , the extension direction of the second die pad connection portion 46AB2 is toward the center of gravity G2 of the third die pad 50B in FIG. 52 . In other words, in plan view, the second die pad connection portion 46AB2 extends toward the center of gravity G2 of the third die pad 50B.

[0493] [Effects] The signal transmission device 10 of the ninth embodiment has the following effects: (9-1) The first lead terminal 14 includes a first outer lead connection portion 14AB1 that is disposed offset in the Y direction with respect to the center of gravity G1 of the first die pad 30, and a first die pad connection portion 14AB2 that is connected to the first die pad 30. The first die pad connection portion 14AB2 extends in a straight line obliquely from the first outer lead connection portion 14AB1 toward the center of gravity G1 of the first die pad 30 in a plan view.

[0494] This configuration reduces the amount of deformation of the first inner lead portion 14A and the first die pad 30 relative to the first outer lead portion 14B, thereby preventing force from being applied to the inter-chip wires WA and the first lead wires WB due to deformation of the first die pad 30.

[0495] (9-2) The second lead terminal 46 includes a second outer lead connection portion 46AB1 that is disposed offset in the Y direction with respect to the center of gravity G2 of the third die pad 50B, and a second die pad connection portion 46AB2 that is connected to the third die pad 50B. In plan view, the second die pad connection portion 46AB2 extends in a straight line obliquely from the second outer lead connection portion 46AB1 toward the center of gravity G2 of the third die pad 50B.

[0496] This configuration reduces the amount of deformation of the second inner lead portion 46A and the third die pad 50B relative to the second outer lead portion 46B, thereby preventing force from being applied to the inter-chip wires WA and the second lead wires WD due to deformation of the third die pad 50B.

[0497] <Tenth Embodiment> A signal transmission device 10 of a tenth embodiment will be described with reference to Figures 53 to 57. The signal transmission device 10 of the tenth embodiment differs from the signal transmission device 10 of the first embodiment in the configuration of the first chip 60. Below, differences in the configuration of the first chip 60 from the first embodiment will be described in detail. Furthermore, components common to the first embodiment will be assigned the same reference numerals, and descriptions thereof will be ...

Claims

1. A first chip including an isolation transformer; A second chip that receives signals from the first chip and / or transmits signals to the first chip; A third chip that receives signals from the first chip and / or transmits signals to 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 third die pad that is disposed at a distance from the first die pad in the first direction and at a distance from the second die pad in a second direction orthogonal to the first direction in a plan view, and on which the third chip is mounted; A plurality of first lead terminals that are disposed on the opposite side of the first die pad from the second die pad and the third die pad in the first direction in a plan view and are arranged in the second direction; A plurality of second lead terminals that are disposed on the opposite side of the second die pad and the third die pad from the first die pad in the first direction and are arranged in the second direction; Inter-chip wires that individually connect the first chip to the second chip and the third chip; A plurality of first lead wires that individually connect the first chip to the plurality of first lead terminals, and The inter-chip wires are formed of a material containing gold, and The first lead wires are formed of a material containing copper or aluminum A signal transmission device.

2. The first lead wires are configured such that palladium is coated on the surface of copper wires 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 to the plurality of second lead terminals, and The second lead wires are 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 to the first die pad, and 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 to the second die pad The wire for the second die pad is formed of a material containing copper or aluminum. The signal transmission device according to claim 1.

6. The wire for the first die pad is a bonding wire, A security bond is formed at a joint portion of the wire for the first die pad with the first die pad. The signal transmission device according to claim 4.

7. The wire for the second die pad is a bonding wire, A security bond is formed at a joint portion of the wire for the second die pad with the second die pad. The signal transmission device according to claim 5.

8. The plurality of first lead terminals include first spaced terminals arranged at a distance from the first die pad, The first spaced terminal, A first portion extending in the first direction, and A second portion continuously provided on the first portion and extending in a direction intersecting the first direction with respect to the first portion in a plan view, and includes, The second portion includes a side surface intersecting in a plan view with the wire for the first lead connected to the second portion, The side surface faces the first die pad in a plan view. The signal transmission device according to claim 1.

9. The shortest distance between the plurality of second lead terminals electrically connected to the second chip and the plurality of second lead terminals electrically connected to the third chip is greater than the distance between the second lead terminals adjacent to each other in the second direction among the plurality of second lead terminals electrically connected to the second chip. The signal transmission device according to claim 1.

10. Further provided is a sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the wire for the first lead, the first die pad, the second die pad, and the third die pad, and partially sealing each of the first lead terminals and each of the second lead terminals, The plurality of first lead terminals, A first connection terminal integrated with the first die pad, and A first spaced terminal arranged at a distance from the first die pad, and Includes, 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.

11. Further provided is a sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad, and for partially sealing each of the first lead terminals and each of the second lead terminals. Each of the first lead terminals includes a first outer lead portion exposed outside the sealing resin, and a first inner lead portion provided inside the sealing resin and connected to the first outer lead portion. The plurality of first lead terminals include a first specific terminal having a through hole formed in the thickness direction of the first lead terminal in the first inner lead portion, and a second specific terminal having no through hole formed in the first inner lead portion. The plurality of first lead wires include a first specific wire joined to the first specific terminal, and a second specific wire joined to the second specific terminal. 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 provided is a rectangular flat sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad, and for partially sealing 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 includes 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, and third and fourth sealing side surfaces connecting the first sealing side surface and the second sealing side surface. Both the third sealing side surface and the fourth sealing side surface are composed only of the sealing resin without exposing a conductive member. The signal transmission device according to claim 1.

13. The first chip includes an element insulating layer, a first resin layer provided on the element insulating layer, and a second resin layer provided on the first resin layer. The insulating transformer includes a surface-side coil disposed on the first resin layer and covered by the second resin layer, and 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 sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad, and partially sealing each of the first lead terminals and each of the second lead terminals, The first chip is 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 dielectric constant than the passivation film, The sealing resin covers the low dielectric layer The signal transmission device according to claim 1.

15. The insulating transformer is a surface-side coil disposed near the chip surface of the first chip, a back-side coil disposed opposite to the surface-side coil, including The surface-side coil is a coil surface, a coil back surface opposite to the coil surface, a coil side surface connecting the coil surface and the coil back surface, having a curved surface is formed between the coil surface and the coil side surface The signal transmission device according to claim 1.

16. The first chip is a flat substrate mounted on the first die pad, an element insulating layer formed on the substrate and provided with at least a part of the insulating transformer, The substrate is a substrate back surface facing the first die pad, a substrate surface opposite to the substrate back surface, a substrate side surface connecting the substrate back surface and the substrate surface, a first portion including the substrate back surface, a second portion provided on the first portion and including the substrate surface, having 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.

17. The first lead terminal is a first outer lead connection portion displaced with respect to the center of gravity of the first die pad in the second direction, a first die pad connection portion connected to the first die pad, including The first die pad connection portion extends linearly obliquely from the first outer lead connection portion toward the center of gravity of the first die pad in a plan view The signal transmission device according to claim 1.

18. Further provided is a sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad, and for partially sealing each of the first lead terminals and each of 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 includes an inner lead surface to which the first lead wire is joined, an inner lead back surface facing the side opposite to the inner lead surface, and an inner lead side surface connecting the inner lead surface and the inner lead back surface. It has The inner lead side surface includes a tip surface facing the first die pad in the second direction. A plating layer is formed on the inner lead surface. No plating layer is formed at an end portion of the inner lead surface on the tip surface side, and it is in contact with the sealing resin. The signal transmission device according to claim 1.

19. Further provided is a sealing resin for sealing the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad, and for partially sealing 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 sealing resin. The first outer lead portion includes an outer lead surface, an outer lead back surface facing the side opposite to the outer lead surface, outer lead side surfaces connecting the outer lead surface and the outer lead back surface at both ends in the width direction of the first outer lead portion, and an outer lead end surface which is an end surface in the direction in which the first outer lead portion extends. It has A plating layer is formed on the outer lead surface, the outer lead back surface, and the outer lead side surfaces. The plating layer is continuously formed from the outer lead back surface toward the outer lead surface at the outer lead end surface and is spaced apart from the outer lead surface. The signal transmission device according to claim 1.

20. Further provided is a sealing resin that seals the first chip, the second chip, the third chip, the inter-chip wire, the first lead wire, the first die pad, the second die pad, and the third die pad and partially seals the first lead terminals and the second lead terminals. The outer surface of the sealing resin is formed such that the surface roughness Rz is 8 μm or more. The signal transmission device according to claim 1.