Semiconductor module

Abstract

To suppress temperature rise of an external terminal and a bonding wire.SOLUTION: A semiconductor module includes: a heat radiation plate; a first insulating substrate disposed on one surface of the heat radiation plate and having a semiconductor chip provided thereon; a frame-shaped case surrounding the first insulating substrate; a plurality of external terminals provided across the inside and the outside of the case and electrically connected to the semiconductor chip via a bonding wire; and at least one second insulating substrate disposed between the heat radiation plate and the external terminals and having heat conductivity greater than that of the case. The at least one second insulating substrate and the one surface of the heat radiation plate are bonded to each other by a heat conductive bonding material. Each external terminal and the at least one second insulating substrate are joined to each other by press-fitting.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor module. [Background technology]

[0002] For example, as disclosed in Patent Documents 1 and 2, a semiconductor module, typified by a power semiconductor module, generally includes an insulating substrate on which a semiconductor chip is provided, a case for accommodating the insulating substrate, and a plurality of external terminals electrically connected to the semiconductor chip.

[0003] In Patent Document 1, main terminals (external terminals) fixed to a housing (case) are electrically connected to a semiconductor chip or an insulating substrate via bonding wires inside the housing. Also, in Patent Document 1, an insulating substrate is disposed on a base plate having excellent thermal conductivity, such as copper or aluminum, and a high heat dissipation insulator is disposed between the base plate and the main terminal to reduce the thermal resistance of the region between the main terminal and the base plate. This high heat dissipation insulator is fixed to the housing together with the main terminal by insert molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-5129 A [Patent Document 2] International Publication No. 2014 / 061211 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the module described in Patent Document 1, the main terminal and the high heat dissipation insulator tend to be out of contact when assembled, so the thermal resistance between the main terminal and the base plate may not be sufficiently reduced. Therefore, in the module described in Patent Document 1, there is a risk that the main terminal and the bonding wires may overheat.

[0006] In consideration of the above circumstances, one aspect of the present disclosure aims to suppress temperature increases in external terminals and bonding wires. [Means for solving the problem]

[0007] In order to solve the above problems, a semiconductor module according to a preferred embodiment of the present disclosure comprises a heat sink, a first insulating substrate arranged on one side of the heat sink and on which a semiconductor chip is provided, a frame-shaped case surrounding the first insulating substrate, a plurality of external terminals arranged inside and outside the case and electrically connected to the semiconductor chip via bonding wires, and at least one second insulating substrate arranged between the heat sink and the plurality of external terminals and having a higher thermal conductivity than the case, wherein the at least one second insulating substrate and one side of the heat sink are joined to each other by a thermally conductive bonding material, and each of the plurality of external terminals and the at least one second insulating substrate are joined to each other by press-fitting. [Brief description of the drawings]

[0008] [Figure 1] 1 is an exploded perspective view of a semiconductor module according to a first embodiment; [Diagram 2] 1 is a cross-sectional view of a semiconductor module according to a first embodiment. [Diagram 3] FIG. 2 is a perspective view of an external terminal in the first embodiment. [Figure 4] 5A to 5C are diagrams for explaining bonding between an external terminal and a second insulating substrate in the first embodiment. [Diagram 5] FIG. 4 is a bottom view of the case to which a plurality of external terminals are fixed. [Figure 6] FIG. 11 is an exploded perspective view of a semiconductor module according to a second embodiment. [Figure 7] FIG. 13 is a perspective view of an external terminal in Modification 1. [Figure 8] 13 is a diagram for explaining bonding between an external terminal and a second insulating substrate in Modification 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions, and some parts are shown diagrammatically to facilitate understanding. In addition, the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0010] 1. First embodiment 1-1. Overall configuration of semiconductor module Fig. 1 is an exploded perspective view of a semiconductor module 10 according to the first embodiment. Fig. 2 is a cross-sectional view of the semiconductor module 10 according to the first embodiment. Fig. 2 shows a cross-section of a part of the semiconductor module 10 cut along a plane perpendicular to the X-axis.

[0011] The semiconductor module 10 is a power module such as an IGBT (Insulated Gate Bipolar Transistor) module. The semiconductor module 10 is used for power control in devices such as inverters or rectifiers mounted on equipment such as railroad cars, automobiles, or household electric machines.

[0012] As shown in Fig. 1, the semiconductor module 10 includes a plurality of first insulating substrates 20, a plurality of semiconductor chips 30, a heat sink 40, a case 50, a plurality of external terminals 60, a plurality of second insulating substrates 70, and a lid 80. Although not shown in Fig. 1, the semiconductor module 10 includes a potting material PA in addition to the above-mentioned components, as shown in Fig. 2. In Fig. 1, the semiconductor chips 30 are simply indicated by two-dot chain lines.

[0013] Hereinafter, each part of the semiconductor module 10 will be described in order based on FIG. 1 and FIG. 2. For convenience, the following description will be made using the X-axis, Y-axis, and Z-axis that are mutually orthogonal. The Z-axis is an axis parallel to the thickness direction of the semiconductor module 10. Hereinafter, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Hereinafter, one direction along the Y-axis is the Y1 direction, and the direction opposite to the Y1 direction is the Y2 direction. Hereinafter, one direction along the Z-axis is the Z1 direction, and the direction opposite to the Z1 direction is the Z2 direction. The relationship between these directions and the vertical direction is not particularly limited and is arbitrary. Hereinafter, viewing in the direction along the Z-axis may be referred to as "planar view".

[0014] Each of the first insulating substrates 20 is a substrate such as a DCB (Direct Copper Bonding) substrate or a DBA (Direct Bonded Aluminum) substrate. Although not shown in FIG. 1, as shown in FIG. 2, the first insulating substrate 20 has an insulating plate 21, a conductor 22 arranged on one surface of the insulating plate 21, and a conductor 23 arranged on the other surface of the insulating plate 21. The insulating plate 21 is an insulating plate-like member arranged so that the thickness direction is along the Z axis. The insulating plate 21 is made of ceramics such as aluminum nitride, aluminum oxide, or silicon nitride. The conductor 22 is a plate-like conductor arranged over substantially the entire surface of the insulating plate 21 facing the Z2 direction. The conductor 23 is arranged on the surface of the insulating plate 21 facing the Z1 direction and is composed of a plurality of plate-like conductors that are appropriately divided. Each of the conductors 22 and 23 is made of a metal such as copper or aluminum.

[0015] A heat sink 40 is joined to the conductor 22 of each of the first insulating substrates 20 by a bonding material B0 such as solder. Meanwhile, a plurality of semiconductor chips 30 are joined to the conductor 23 of each of the first insulating substrates 20 by a bonding material such as solder. In this manner, the first insulating substrate 20 is disposed on one surface of the heat sink 40, and the semiconductor chips 30 are provided thereon. The number of semiconductor chips 30 mounted on each of the first insulating substrates 20 is arbitrary. Furthermore, the number of first insulating substrates 20 included in the semiconductor module 10 is not limited to the example shown in FIG. 1, and may be two or less or four or more.

[0016] At least one element of the multiple semiconductor chips 30 mounted on the first insulating substrate 20 is a power semiconductor chip such as an IGBT. Note that the first insulating substrate 20 may be mounted with, as the semiconductor chip 30, a control chip for controlling the operation of the power semiconductor chip, in addition to a switching element such as an IGBT, or an element such as an FWD (Free Wheeling Diode) for commutating a load current.

[0017] The heat sink 40 is a plate-shaped member for heat dissipation arranged so that the thickness direction is along the Z axis. The heat sink 40 is made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. The heat sink 40 has high thermal conductivity and dissipates heat from the semiconductor chip 30. The heat sink 40 also has high electrical conductivity and is electrically connected to, for example, a reference potential such as a ground potential. Note that the heat sink 40 is not limited to a metal plate as long as it has high thermal conductivity, and may be an insulator such as ceramics. A heat dissipation member such as a heat dissipation fin may be integrally provided on the surface of the heat sink 40 facing the Z2 direction.

[0018] In the example shown in FIG. 1, the heat sink 40 has a shape having a pair of long sides extending in the direction along the X-axis and a pair of short sides extending in the direction along the Y-axis when viewed in the direction along the Z-axis. The heat sink 40 has mounting holes 41 provided in the vicinity of each short side. The mounting holes 41 are, for example, through holes used to screw a heat dissipation member such as a heat dissipation fin (not shown) to the heat sink 40. The planar shape and number of the heat sink 40 are not limited to the example shown in FIG. 1 and are arbitrary. The mounting holes 41 may be provided as necessary and may be omitted.

[0019] The case 50 is a frame-shaped member that houses the first insulating substrates 20 and the semiconductor chips 30. Here, the case 50 is arranged so that the thickness direction is along the Z axis, and forms a frame surrounding the first insulating substrates 20 in a plan view. The case 50 is substantially an insulator, and is made of a resin material such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene terephthalate). The resin material may contain an inorganic filler such as alumina or silica from the viewpoint of improving the mechanical strength of the case 50 or reducing the linear expansion coefficient.

[0020] In the example shown in FIG. 1, the case 50 has an outer shape having a pair of long sides extending in the direction along the X-axis and a pair of short sides extending in the direction along the Y-axis when viewed in the direction along the Z-axis. The case 50 is also provided with a plurality of holes 52 and a plurality of holes 53. The plurality of holes 52 are holes used to screw a board (not shown) on which the semiconductor module 10 is mounted to the case 50. The plurality of holes 53 are through holes used to screw a heat dissipation member such as a heat dissipation fin (not shown) to the heat dissipation plate 40 together with the above-mentioned mounting hole 41. The shape of the case 50 is not limited to the example shown in FIG. 1 and is arbitrary. The holes 52 and 53 may be provided as necessary and may be omitted.

[0021] A plurality of external terminals 60 are fixed to the above-described case 50. Here, the case 50 is formed by insert molding in which each of the plurality of external terminals 60 is an insert part. This allows the external terminals 60 to be firmly and stably fixed to the case 50, so that the external terminals 60 can be joined to the second insulating substrate 70 by press-fitting in a state in which they are fixed to the case 50, as described below.

[0022] Each of the multiple external terminals 60 is a terminal for electrically connecting a substrate (not shown) on which the semiconductor module 10 is mounted and the semiconductor chip 30 to each other. Here, as shown in FIG. 2, each external terminal 60 is provided on the inside and outside of the case 50, and is electrically connected to the semiconductor chip 30 via a bonding wire BW. The multiple external terminals 60 are made of a metal such as copper, a copper alloy, aluminum, an aluminum alloy, or an iron alloy. Furthermore, the surface of the external terminal 60 may be plated with, for example, Sn plating or Sn-Cu plating.

[0023] Of the multiple external terminals 60 that the semiconductor module 10 has, two or more external terminals 60 are terminals through which a main current flows, and the other two or more external terminals 60 are control terminals for controlling the operation of the semiconductor chip 30 .

[0024] The external terminal 60 is formed of a metal plate bent roughly into an L-shape. Here, the external terminal 60 has a pin portion 61, a leg portion 62, a protrusion 63, and a hole 64, as shown in FIG.

[0025] The pin portion 61 is a part of the external terminal 60, and is a rod-shaped portion extending in a direction along the Z axis. An end of the pin portion 61 in the Z1 direction protrudes from the outer wall surface of the case 50. Thus, the pin portion 61 has a terminal portion that protrudes from the outer wall surface of the case 50. The terminal portion is connected to a board (not shown) on which the semiconductor module 10 is mounted. Meanwhile, a leg portion 62 is connected to an end of the pin portion 61 in the Z2 direction. Note that the shape of the pin portion 61 is not limited to the example shown in FIG. 1, and for example, the tip of the pin portion 61 may be shaped to branch into two portions.

[0026] The leg 62 is a part of the external terminal 60, and is a plate-like portion disposed along the surface of the second insulating substrate 70 facing the Z1 direction. The leg 62 extends from the end of the pin portion 61 in the Z2 direction toward the inside of the case 50. The leg 62 has a portion sandwiched between the case 50 and the second insulating substrate 70, and a pad portion that is exposed to the inside of the case 50. One end of the bonding wire BW shown in FIG. 2 is joined to the pad portion. The other end of the bonding wire BW is connected to the first insulating substrate 20 or the semiconductor chip 30. This connection electrically connects the external terminal 60 and the semiconductor chip 30 to each other.

[0027] The protrusion 63 is a part of the external terminal 60, and is a portion that protrudes in the Z2 direction from the leg portion 62. The hole 64 is a hole that is provided in association with the formation of the protrusion 63 when the external terminal 60 is formed by bending a metal plate. The details of the protrusion 63 and the hole 64 will be described later with reference to Figs. 3 and 4.

[0028] The second insulating substrates 70 are disposed between the heat sink 40 and the external terminals 60, and are members having higher thermal conductivity than the case 50. Each second insulating substrate 70 is disposed so that the thickness direction is along the Z axis. In this embodiment, the second insulating substrates 70 are separated for each external terminal 60, and correspond one-to-one to the external terminals 60. Therefore, the corresponding second insulating substrate 70 is interposed between the heat sink 40 and each external terminal 60. In addition to the second insulating substrates 70 corresponding to the external terminals 60, there may be a second insulating substrate 70 interposed between the heat sink 40 and the case 50 without contributing to the bonding with the external terminals 60.

[0029] Each second insulating substrate 70 has the same layer structure as the first insulating substrate 20. That is, each second insulating substrate 70 is a substrate such as a DCB (Direct Copper Bonding) substrate or a DBA (Direct Bonded Aluminum) substrate. Therefore, the cost of the semiconductor module 10 can be reduced compared to a configuration in which the first insulating substrate 20 and the second insulating substrate 70 have different layer structures.

[0030] Specifically, as shown in FIG. 1 and FIG. 2, the second insulating substrate 70 has an insulating plate 71, a first conductor 72 arranged on one surface of the insulating plate 71, and a second conductor 73 arranged on the other surface of the insulating plate 71. The insulating plate 71 is an insulating plate-like member arranged so that the thickness direction is along the Z axis. The insulating plate 71 is made of ceramics such as aluminum nitride, aluminum oxide, or silicon nitride. The first conductor 72 is a plate-like conductor arranged over substantially the entire surface of the insulating plate 71 facing the Z2 direction, and is joined to one surface of the heat sink 40 by a joining material B1 described later. The second conductor 73 is a plate-like conductor arranged over substantially the entire surface of the insulating plate 71 facing the Z1 direction, and is separated for each of the external terminals 60 of the multiple external terminals 60. However, the second conductor 73 is provided with a notch 73a. Each of the first conductor 72 and the second conductor 73 is made of a metal such as copper or aluminum.

[0031] Here, the notches 73a form recesses 74 into which the above-mentioned protrusions 63 are press-fitted. As a result, each of the multiple external terminals 60 and the multiple second insulating substrates 70 are joined to each other by press-fitting. Details of the recesses 74 will be described later with reference to Figs. 3 and 4.

[0032] On the other hand, the surface of each second insulating substrate 70 facing the Z2 direction is bonded to the surface of the heat sink 40 facing the Z1 direction by a bonding material B1. The bonding material B1 is, for example, solder. The solder is not particularly limited, but may be, for example, a lead-free solder such as SnAg-based, SnAgCu-based, SnBi-based, SnZnBi-based, SnCu-based, SnAgBi-based, SnSb-based, or SnZnAl-based. In this way, the multiple second insulating substrates 70 and one surface of the heat sink 40 are bonded to each other by a thermally conductive bonding material B1. The bonding material B1 is not limited to solder, and may be, for example, an adhesive such as an epoxy adhesive, an acrylic adhesive, a urethane adhesive, or a silicone adhesive containing an inorganic filler such as silica or alumina.

[0033] Here, the heat sink 40 and the case 50 are joined by an adhesive B2. The adhesive B2 is an insulating adhesive. More specifically, the adhesive B2 is, for example, an epoxy adhesive, an acrylic adhesive, a urethane adhesive, or a silicone adhesive. The adhesive B2 may contain an insulating inorganic filler such as alumina or silica. The arrangement of the adhesive B2 will be described later with reference to FIG. 5.

[0034] The lid 80 is a plate-like member bonded to a surface of the case 50 facing the Z1 direction. The lid 80 is made of a resin material such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene terephthalate) like the case 50. The lid 80 is bonded to the case 50 with an adhesive or the like so as to seal the gap between the lid 80 and the case 50.

[0035] 2, the space surrounded by the heat sink 40, the case 50, and the lid 80 is filled with a potting material PA that covers the semiconductor chip 30. The potting material PA is made of, for example, a silicone resin such as silicone gel.

[0036] In the semiconductor module 10 outlined above, each external terminal 60 is connected to the heat sink 40 via the second insulating substrate 70, which has a higher thermal conductivity than the case 50, so that Joule heat generated in the bonding wire BW and the external terminal 60 can be released to the heat sink 40 via the second insulating substrate 70. Here, the second insulating substrate 70 and the heat sink 40 are bonded to each other by the bonding material B1, which has a high thermal conductivity, so that the thermal resistance between the second insulating substrate 70 and the heat sink 40 can be reduced. Moreover, since the external terminal 60 and the second insulating substrate 70 are bonded to each other by press-fitting, the thermal resistance between the external terminal 60 and the second insulating substrate 70 can be reduced while facilitating the assembly of the external terminal 60 and the second insulating substrate 70. From the above, it is possible to suppress the temperature rise of the external terminal 60 and the bonding wire BW.

[0037] 1-2. External terminals and second insulating substrate Fig. 3 is a perspective view of the external terminal 60 in the first embodiment. Fig. 4 is a diagram for explaining the bonding between the external terminal 60 and the second insulating substrate 70 in the first embodiment. As shown in Fig. 3 and Fig. 4, the external terminal 60 has a shape bent along a straight line LN along the boundary between the pin portion 61 and the leg portion 62, and is integrally formed by bending a metal plate or the like.

[0038] In this way, by forming each of the multiple external terminals 60 by bending a metal plate, the cost of the semiconductor module 10 can be reduced compared to a mode in which the external terminals 60 are manufactured by welding or the like.

[0039] 3 and 4, the protrusion 63 is disposed along the same plane as the pin portion 61. Here, the leg portion 62 is provided with a hole 64 corresponding to the protrusion 63, which is formed during bending of the metal plate.

[0040] Thus, each of the multiple external terminals 60 has a projection 63 that projects toward the second insulating substrate 70.

[0041] On the other hand, recess 74 of second insulating substrate 70 is a depression that opens in the Z1 direction. In the example shown in Fig. 4, recess 74 is configured using notch 73a provided in second conductor 73. Here, recess 74 is configured with a wall surface defined by notch 73a and a bottom surface defined by the surface of insulating plate 71 facing the Z1 direction.

[0042] Thus, each second insulating substrate 70 has a recess 74 that fits into the protrusion 63 by press-fitting. Therefore, compared to a mode in which the recess 74 provided in the external terminal 60 and the protrusion provided in the second insulating substrate 70 are joined by press-fitting, there is an advantage in that it is easier to increase the contact area between the external terminal 60 and the second insulating substrate 70 for reasons such as the fact that it is easier to make the above-mentioned hole 64 smaller than the notch 66 in Modification 1 described below.

[0043] Furthermore, by forming the recess 74 using a notch penetrating the second conductor 73, the external terminal 60 and the second insulating substrate 70 can be easily joined to each other by press-fitting. The second conductor 73 may have a hole penetrating the second conductor 73. In this case, the recess 74 may be formed using the hole instead of the notch 73a.

[0044] As described above, the layer structure of the second insulating substrate 70 is the same as the layer structure of the first insulating substrate 20. To be more specific, the insulating plate 71 of the second insulating substrate 70 is configured with the same thickness and made of the same material as the insulating plate 21 of the first insulating substrate 20. Furthermore, the first conductor 72 of the second insulating substrate 70 is configured with the same thickness and made of the same material as the conductor 22 of the first insulating substrate 20. Furthermore, the second conductor 73 of the second insulating substrate 70 is configured with the same thickness and made of the same material as the conductor 23 of the first insulating substrate 20.

[0045] The above-mentioned projections 63 are press-fitted into the recesses 74. In this way, the external terminals 60 and the second insulating substrate 70 are joined to each other.

[0046] Here, since the second conductors 73 are separated for each external terminal 60, the external terminals 60 can be joined to the second conductors 73 by press-fitting while preventing electrical continuity between the external terminals 60. In addition, since there are multiple second insulating substrates 70, the thermal stress between the second insulating substrate 70 and the case 50 can be reduced compared to an embodiment in which there is only one second insulating substrate 70.

[0047] Moreover, the multiple second insulating substrates 70 are separated for each external terminal 60. Therefore, the second insulating substrates 70 can be shared among semiconductor modules 10 having different arrangements of the external terminals 60. As a result, the cost of the semiconductor module 10 can be reduced.

[0048] Each of the multiple external terminals 60 has a protrusion 63 protruding toward at least one second insulating substrate 70. At least one second insulating substrate 70 has a recess 74 into which the protrusion 63 fits by press-fitting. This has the advantage that the contact area between the external terminal 60 and the second insulating substrate 70 can be easily increased compared to a mode in which the recess 74 provided on the external terminal 60 and the protrusion provided on the second insulating substrate 70 are joined by press-fitting.

[0049] The width W2 of the recess 74 is larger than the width W1 of the protrusion 63 so that the protrusion 63 has a tightening margin that allows the protrusion 63 to be press-fitted into the recess 74. The tightening margin is about 0.04 mm or more and 0.18 mm or less. Here, the width W1 is the maximum width of the protrusion 63. On the other hand, the width W2 is the minimum width of the recess 74. In the example shown in FIG. 3 and FIG. 4, the widths of the protrusion 63 and the recess 74 are constant. The width of the protrusion 63 does not have to be constant. For example, the protrusion 63 may have a tapered surface so that the width becomes smaller toward the Z2 direction. Also, the width of the recess 74 does not have to be constant. For example, the recess 74 may have a tapered surface so that the width becomes larger toward the Z1 direction.

[0050] The protruding length L1 of the protrusion 63 is equal to or less than the depth D1 of the recess 74, i.e., the thickness t of the second conductor 73. This eliminates the need for processing to form the recess 74 in the insulating plate 71, making it easy to manufacture the second insulating substrate 70. In addition, the protrusion 63 can be pressed into the recess 74 up to its base. As a result, the surface of the leg 62 facing the Z2 direction and the surface of the second conductor 73 facing the Z1 direction can be brought into contact over a wide range. This increases the contact area between the external terminal 60 and the second insulating substrate 70, thereby reducing the thermal resistance between the external terminal 60 and the second insulating substrate 70.

[0051] A gap may be formed between the external terminal 60 and the second insulating substrate 70. In this case, it is preferable that a heat transfer material such as an adhesive or grease having excellent thermal conductivity is interposed in the gap.

[0052] The surface of the second insulating substrate 70 facing the Z2 direction is bonded to the surface of the heat sink 40 facing the Z1 direction with a bonding material B1 having excellent thermal conductivity. The bonding material B1 is, for example, solder. This makes it possible to firmly bond the heat sink 40 and the second insulating substrate 70 with the bonding material B1 and to reduce the thermal resistance between the heat sink 40 and the second insulating substrate 70.

[0053] The solder is not particularly limited, and may be, for example, a lead-free solder such as SnAg-based, SnAgCu-based, SnBi-based, SnZnBi-based, SnCu-based, SnAgBi-based, SnSb-based, or SnZnAl-based, etc. The bonding material B1 is not limited to solder, and may be, for example, an adhesive such as an epoxy-based adhesive, an acrylic-based adhesive, a urethane-based adhesive, or a silicone-based adhesive containing an inorganic filler such as silica or alumina.

[0054] Here, the heat sink 40 and the case 50 are joined together by an adhesive B2.

[0055] Fig. 5 is a bottom view of the case 50 to which a plurality of external terminals 60 are fixed. In Fig. 5, the case 50 is shown together with the plurality of external terminals 60 as viewed in the Z1 direction.

[0056] As shown in FIG. 5, legs 62 of a plurality of external terminals 60 are arranged on the bottom surface of the case 50, that is, on the surface of the case 50 facing the Z2 direction.

[0057] 5, the adhesive B2 is provided over the entire outer periphery of the heat sink 40. Here, the adhesive B2 is arranged so as to avoid the leg 62 of the external terminal 60, and has a plurality of portions B2a and B2b. The portion B2a is a part of the adhesive B2, and is a portion for joining the surface of the heat sink 40 facing the Z1 direction to the case 50, and is arranged so as to avoid the leg 62 of the external terminal 60. The portion B2b is a part of the adhesive B2, and is a portion for joining the side surface of the heat sink 40 to the case 50, and is arranged over the entire periphery of the side surface of the heat sink 40.

[0058] In this manner, the case 50 and the heat sink 40 are joined to each other by the adhesive B2. Therefore, the gap between the case 50 and the heat sink 40 can be sealed by the adhesive B2 while ensuring insulation between the external terminals 60 and the heat sink 40.

[0059] The adhesive B2 may be in contact with the external terminal 60 or may be in contact with the second insulating substrate 70. In other words, the adhesive B2 may not only bond the heat sink 40 and the case 50 to each other, but may also bond one or both of the leg 62 of the external terminal 60 and the second insulating substrate 70 to the heat sink 40 and the case 50.

[0060] As described above, in the semiconductor module 10, the temperature rise of the external terminals 60 and the bonding wires BW can be suppressed.

[0061] 2. Second embodiment A second embodiment of the present disclosure will be described below. In the following example, for elements having the same actions and functions as those in the above embodiment, the reference numerals used in the description of the above embodiment will be used and detailed descriptions of each will be omitted as appropriate.

[0062] 6 is an exploded perspective view of a semiconductor module 10A according to the second embodiment. The semiconductor module 10A has the same configuration as the semiconductor module 10 of the first embodiment, except that the semiconductor module 10A has one second insulating substrate 70 instead of the multiple second insulating substrates 70 of the first embodiment.

[0063] The second insulating substrate 70A is configured similarly to the second insulating substrate 70 of the first embodiment, except that it has one insulating plate 71A and one first conductor 72A instead of the multiple insulating plates 71 and multiple first conductors 72 of the first embodiment.

[0064] The insulating plate 71A is configured similarly to the insulating plate 71A of the first embodiment, except that it has a frame shape that conforms to the frame shape of the case 50. The first conductor 72A is configured similarly to the first conductor 72 of the first embodiment, except that it is provided over the entire area in the circumferential direction of the insulating plate 71A.

[0065] The second embodiment described above can also suppress the temperature rise of the external terminals 60 and the bonding wires BW. In this embodiment, a plurality of second conductors 73 are arranged for each external terminal 60 on the surface of the insulating plate 71A of one second insulating substrate 70A. This makes it easy to position the second insulating substrate 70A relative to the heat sink 40. In addition, by increasing the contact area between the heat sink 40 and the second insulating substrate 70A, the thermal resistance between the heat sink 40 and the second insulating substrate 70A can also be reduced.

[0066] 3. Variations The present disclosure is not limited to the above-described embodiments, and various modifications are possible. In addition, the embodiments and modifications may be combined as appropriate.

[0067] 3-1. Variation 1 Fig. 7 is a perspective view of an external terminal 60B in Modification 1. Fig. 8 is a diagram for explaining the bonding between the external terminal 60B and a second insulating substrate 70B in Modification 1. As shown in FIGS. 7 and 8, the external terminal 60B has a pin portion 61, a leg portion 62, a recess 65, and a notch 66.

[0068] The recess 65 is a part of the external terminal 60B, and is a depression that opens in the Z2 direction from the leg portion 62. The notch 66 is a missing portion that is provided in association with the formation of the recess 65 when the external terminal 60B is formed by bending a metal plate. The shape of the recess 65 is not limited to the examples shown in Figs. 7 and 8, and may be any shape.

[0069] The second insulating substrate 70B is configured similarly to the second insulating substrate 70 of the first embodiment, except that it has a second conductor 73B instead of the second conductor 73 of the first embodiment. The second conductor 73B has a portion 73b. The portion 73b constitutes a protrusion 75 that receives the press-fit of the recess 65. The shape of the portion 73b is not limited to the examples shown in Figs. 7 and 8, and may be any shape.

[0070] The above-described first modification also makes it possible to suppress a rise in temperature of the external terminals 60B and the bonding wires BW.

[0071] 3-2. Variation 2 In the above embodiment, the layer structure of the second insulating substrates 70, 70A, and 70B is the same as that of the first insulating substrate 20, but the present invention is not limited to this, and a second insulating substrate having a layer structure different from that of the first insulating substrate 20 may be used. For example, the thickness and number of layers of the second insulating substrate may be different from those of the first insulating substrate 20.

[0072] 3-3. Variation 3 In the above-described first embodiment, an insulating plate 71 is provided for each external terminal 60, but the insulating plate 71 may be integrally configured for each of a plurality of external terminals 60. Here, for example, an insulating plate 71 corresponding to two external terminals 60 and an insulating plate 71 corresponding to one external terminal 60 may be mixed.

[0073] 4. Notes For example, the following aspects can be understood from the above embodiment and modified examples.

[0074] (Additional Note 1) A semiconductor module of a first aspect of the present disclosure comprises a heat sink, a first insulating substrate arranged on one side of the heat sink and on which a semiconductor chip is provided, a frame-shaped case surrounding the first insulating substrate, a plurality of external terminals provided on the inside and outside of the case and electrically connected to the semiconductor chip via bonding wires, and at least one second insulating substrate arranged between the heat sink and the plurality of external terminals and having higher thermal conductivity than the case, wherein the at least one second insulating substrate and one side of the heat sink are joined to each other by a thermally conductive bonding material, and each of the plurality of external terminals and the at least one second insulating substrate are joined to each other by press-fitting.

[0075] In the above embodiment, each external terminal is connected to the heat sink via the second insulating substrate, which has a higher thermal conductivity than the case, so that Joule heat generated in the bonding wire and the external terminal can be released to the heat sink via the second insulating substrate. Here, the second insulating substrate and the heat sink are bonded to each other with a bonding material having a high thermal conductivity, so that the thermal resistance between the second insulating substrate and the heat sink can be reduced. Moreover, the external terminal and the second insulating substrate are bonded to each other by press-fitting, so that the thermal resistance between the external terminal and the second insulating substrate can be reduced while facilitating the assembly of the external terminal and the second insulating substrate. From the above, it is possible to suppress the temperature rise of the external terminal and the bonding wire.

[0076] (Additional Note 2) In the second embodiment, which is a preferred example of the first embodiment, the at least one second insulating substrate is a plurality of second insulating substrates, each of which has an insulating plate, a first conductor disposed on one surface of the insulating plate and bonded to one surface of the heat sink by the bonding material, and at least one second conductor disposed on the other surface of the insulating plate and separated for each of the plurality of external terminals. In the above embodiment, since the second insulating substrate has an insulating plate, a first conductor, and a second conductor, a substrate such as a DCB (Direct Copper Bonding) substrate or a DBA (Direct Bonded Aluminum) substrate can be used as the second insulating substrate. Here, since the second conductor is separated for each external terminal, the external terminals can be bonded to the second conductor by press-fitting while preventing electrical conduction between the external terminals. In addition, since there are a plurality of second insulating substrates, the thermal stress between the second insulating substrate and the case can be reduced compared to the embodiment in which there is only one second insulating substrate.

[0077] (Note 3) In the third aspect, which is a preferred example of the second aspect, the second insulating substrates are separated for each of the external terminals. In the above aspect, the second insulating substrate can be shared among semiconductor modules having different arrangements of the external terminals. As a result, the cost of the semiconductor module can be reduced.

[0078] (Additional Note 4) In a fourth embodiment, which is a preferred example of the first embodiment, the at least one second insulating substrate is one second insulating substrate, and the one second insulating substrate has an insulating plate, a first conductor arranged on one surface of the insulating plate and bonded to one surface of the heat sink by the bonding material, and a plurality of second conductors arranged on the other surface of the insulating plate and separated for each of the external terminals of the plurality of external terminals. In the above embodiment, since the second insulating substrate has an insulating plate, a first conductor, and a second conductor, a substrate such as a DCB substrate or a DBA substrate can be used as the second insulating substrate. Here, since a plurality of second conductors for each external terminal are arranged on the surface of the insulating plate of one second insulating substrate, the positioning of the second insulating substrate with respect to the heat sink can be easily performed. In addition, by increasing the contact area between the heat sink and the second insulating substrate, the thermal resistance between the heat sink and the second insulating substrate can also be reduced.

[0079] (Note 5) In a fifth aspect which is a preferred example of any one of the first to fourth aspects, the case and the heat sink are joined to each other with an adhesive. In the above aspect, the gap between the case and the heat sink can be sealed with the adhesive while ensuring insulation between the external terminals and the heat sink.

[0080] (Note 6) In a sixth aspect which is a preferred example of any one of the first to fifth aspects, the at least one second insulating substrate has the same layer structure as the first insulating substrate. In the above aspect, the cost of the semiconductor module can be reduced compared to an aspect in which the first insulating substrate and the second insulating substrate have different layer structures.

[0081] (Note 7) In a seventh aspect which is a preferred example of any of the first to sixth aspects, each of the plurality of external terminals has a protrusion protruding toward the at least one second insulating substrate, and the at least one second insulating substrate has a recess into which the protrusion fits by press-fitting. The above aspect has an advantage that it is easier to increase the contact area between the external terminal and the second insulating substrate, compared to an aspect in which the recess provided on the external terminal and the protrusion provided on the second insulating substrate are joined by press-fitting.

[0082] (Note 8) In an eighth aspect which is a preferred example of the seventh aspect, the recess is formed using a hole or a notch penetrating the second conductor of the at least one second insulating substrate. In the above aspect, the external terminal and the second insulating substrate can be easily joined to each other by press-fitting.

[0083] (Note 9) In a ninth aspect which is a preferred example of the seventh or eighth aspect, the protrusion length of the protrusion is equal to or less than the thickness of the second conductor of the at least one second insulating substrate. In the above aspect, since no processing is required to form a recess in the insulating plate, the second insulating substrate is easily manufactured.

[0084] (Appendix 10) In a tenth aspect which is a preferred example of any one of the first to ninth aspects, each of the plurality of external terminals is formed by bending a metal plate. In the above aspect, the cost of the semiconductor module can be reduced compared to an aspect in which the external terminals are manufactured by welding or the like.

[0085] (Note 11) In an eleventh aspect which is a preferred example of any one of the first to tenth aspects, the bonding material is solder. In the above aspect, the heat sink and the second insulating substrate are firmly bonded by the bonding material, and the thermal resistance between the heat sink and the second insulating substrate can be reduced.

[0086] (Appendix 12) In a twelfth aspect, which is a preferred example of any one of the first to eleventh aspects, the case is formed by insert molding in which each of the plurality of external terminals is an insert part. In the above aspect, the external terminals are firmly and stably fixed to the case, so that the external terminals can be joined to the second insulating substrate by press-fitting in a state where they are fixed to the case. [Explanation of symbols]

[0087] 10...semiconductor module, 10A...semiconductor module, 20...first insulating substrate, 21...insulating plate, 22...conductor, 23...conductor, 30...semiconductor chip, 40...heat sink, 41...mounting hole, 50...case, 52...hole, 53...hole, 60...external terminal, 60B...external terminal, 61...pin portion, 62...leg portion, 63...projection, 64...hole, 65...recess, 66...notch, 70...second insulating substrate, 70A...second insulating substrate, 70B... Second insulating substrate, 71...insulating plate, 71A...insulating plate, 72...first conductor, 72A...first conductor, 73...second conductor, 73B...second conductor, 73a...notch, 73b...portion, 74...recess, 75...protrusion, 80...lid, B0...bonding material, B1...bonding material, B2...adhesive, B2a...portion, B2b...portion, BW...bonding wire, D1...depth, LN...straight line, PA...potting material, W1...width, W2...width, t...thickness.

Claims

1. A heat sink; a first insulating substrate on one surface of the heat sink, the first insulating substrate having a semiconductor chip mounted thereon; a frame-shaped case surrounding the first insulating substrate; a plurality of external terminals provided on the inside and outside of the case and electrically connected to the semiconductor chip via bonding wires; at least one second insulating substrate disposed between the heat sink and the plurality of external terminals and having a higher thermal conductivity than the case; the at least one second insulating substrate and one surface of the heat sink are bonded to each other by a thermally conductive bonding material; Each of the plurality of external terminals and the at least one second insulating substrate are joined to each other by press-fitting. Semiconductor module.

2. the at least one second insulating substrate is a plurality of second insulating substrates; Each of the plurality of second insulating substrates is An insulating plate; a first conductor disposed on one surface of the insulating plate and joined to one surface of the heat sink by the joining material; At least one second conductor is disposed on the other surface of the insulating plate and separated for each of the plurality of external terminals. The semiconductor module according to claim 1 .

3. The plurality of second insulating substrates are separated for each of the plurality of external terminals. The semiconductor module according to claim 2 .

4. the at least one second insulating substrate is one second insulating substrate, The one second insulating substrate is An insulating plate; a first conductor disposed on one surface of the insulating plate and joined to one surface of the heat sink by the joining material; a plurality of second conductors arranged on the other surface of the insulating plate and separated for each of the plurality of external terminals; The semiconductor module according to claim 1 .

5. The case and the heat sink are joined to each other by an adhesive.

5. The semiconductor module according to claim 2 or 4.

6. The at least one second insulating substrate has the same layer structure as the first insulating substrate.

5. The semiconductor module according to claim 2 or 4.

7. each of the plurality of external terminals has a projection protruding toward the at least one second insulating substrate; the at least one second insulating substrate has a recess that fits into the protrusion by press-fitting; 5. The semiconductor module according to claim 2 or 4.

8. The recess is configured using a hole or a notch penetrating the second conductor of the at least one second insulating substrate. The semiconductor module according to claim 7 .

9. A protruding length of the protrusion is equal to or less than a thickness of the second conductor of the at least one second insulating substrate. The semiconductor module according to claim 7 .

10. Each of the plurality of external terminals is formed by bending a metal plate. The semiconductor module according to claim 7 .

11. The bonding material is solder. The semiconductor module according to claim 1 .

12. the case is formed by insert molding in which each of the plurality of external terminals is an insert component. The semiconductor module according to claim 1 .

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