Semiconductor module

Abstract

The invention relates to a semiconductor module. The present invention suppresses temperature rise of an external terminal and a bonding wire. The semiconductor module includes: a heat dissipation plate; a first insulating substrate, which is disposed on the first surface of the heat dissipation plate, and on which a semiconductor chip is provided; a frame-shaped housing that surrounds the first insulating substrate; a plurality of external terminals provided across the inside and outside of the case and electrically connected to the semiconductor chip via bonding wires; and at least one second insulating substrate that is disposed between the heat dissipation plate and the plurality of external terminals and has thermal conductivity higher than that of the housing, the at least one second insulating substrate and the first surface of the heat dissipation plate being bonded 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 being bonded to each other by press-fitting.

Description

Technical Field

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

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

[0003] In Patent Document 1, the main terminal (external terminal) fixed to the housing (shell) is electrically connected to the semiconductor chip or the insulating substrate by means of bonding wires in the housing. In addition, in Patent Document 1, an insulating substrate is arranged on a base plate of a material with excellent thermal conductivity such as copper or aluminum, and a high heat dissipation insulator is arranged between the base plate and the main terminal in order to reduce the thermal resistance of the area between the main terminal and the base plate. The high heat dissipation insulator is fixed to the housing together with the main terminal by insert molding.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-5129

[0007] Patent Document 2: International Publication No. 2014 / 061211 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, in the module described in Patent Document 1, the main terminal and the high heat dissipation insulator are easily in a non-contact state during assembly, 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, the main terminal and the bonding wire may be overheated.

[0010] In view of the above circumstances, an object of one aspect of the present disclosure is to suppress a temperature increase of an external terminal and a bonding wire.

[0011] Solutions for solving problems

[0012] In order to solve the above problems, the semiconductor module of the preferred technical solution of the present invention comprises: a heat sink; a first insulating substrate, which is arranged on the first surface of the heat sink, and a semiconductor chip is provided on the first insulating substrate; a frame-shaped shell, which surrounds the first insulating substrate; a plurality of external terminals, which are arranged across the inside and outside of the shell and are electrically connected to the semiconductor chip by means of bonding wires; and at least one second insulating substrate, which is arranged between the heat sink and the plurality of external terminals and has a thermal conductivity higher than that of the shell, the at least one second insulating substrate and the first surface of the heat sink are bonded to each other using a thermally conductive bonding material, and the plurality of external terminals are each bonded to the at least one second insulating substrate by pressing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an exploded perspective view of the semiconductor module according to the first embodiment.

[0014] Figure 2 It is a cross-sectional view of the semiconductor module according to the first embodiment.

[0015] Figure 3 It is a perspective view of the external terminal in the first embodiment.

[0016] Figure 4 It is a diagram for explaining the bonding between the external terminal and the second insulating substrate in the first embodiment.

[0017] Figure 5 It is a bottom view of a housing to which a plurality of external terminals are fixed.

[0018] Figure 6 It is an exploded perspective view of the semiconductor module according to the second embodiment.

[0019] Figure 7 This is a perspective view of an external terminal in Modification 1.

[0020] Figure 8 This is a diagram for explaining the bonding between the external terminal and the second insulating substrate in Modification Example 1.

[0021] Description of Reference Numerals

[0022] 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, housing; 52, hole; 53, hole; 60, external terminal; 60B, external terminal; 61, pin; 62, foot; 63, protrusion; 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, part; 74, recess; 75, convex part; 80, cover; B0, bonding material; B1, bonding material; B2, adhesive; B2a, part; B2b, part; BW, bonding line; D1, depth; LN, straight line; PA, potting material; W1, width; W2, width; t, thickness. DETAILED DESCRIPTION

[0023] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the dimensions and scales of the various parts in the accompanying drawings are appropriately different from the actual situation, and there are also parts that are schematically shown for easy understanding. In addition, as long as there is no record of the meaning of the present disclosure being particularly limited in the following description, the scope of the present disclosure is not limited to these embodiments.

[0024] 1. First Implementation Method

[0025] 1-1. Overall structure of semiconductor module

[0026] Figure 1 It is an exploded perspective view of the semiconductor module 10 according to the first embodiment. Figure 2 FIG. 1 is a cross-sectional view of a semiconductor module 10 according to the first embodiment. Figure 2 , a cross section obtained by cutting a part of the semiconductor module 10 along a plane perpendicular to the X-axis is shown.

[0027] The semiconductor module 10 is a power module such as an IGBT (Insulated Gate Bipolar Transistor) module, etc. The semiconductor module 10 is used for power control in devices such as inverters and rectifiers mounted in equipment such as railway vehicles, automobiles, or household electrical appliances.

[0028] like Figure 1 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 housing 50, a plurality of external terminals 60, a plurality of second insulating substrates 70, and a cover 80. Figure 1 The illustration is omitted, but Figure 2As shown in FIG. 1 , the semiconductor module 10 includes a potting material PA in addition to the above-mentioned components. Figure 1 In FIG. 1 , the semiconductor chip 30 is schematically shown by a two-dot chain line.

[0029] Below, first, based on Figure 1 and Figure 2 , each part of the semiconductor module 10 is described in sequence. In addition, for convenience, the following description is appropriately carried out using mutually orthogonal X-axis, Y-axis and Z-axis. The Z-axis is an axis parallel to the thickness direction of the semiconductor module 10. In the following, a direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. A direction along the Y-axis is the Y1 direction, and the direction opposite to the Y1 direction is the Y2 direction. A 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, but arbitrary. In addition, in the following, the situation of observing in the direction along the Z-axis is sometimes referred to as "looking down".

[0030] Each of the plurality of first insulating substrates 20 is a DCB (Direct Copper Bonding) substrate or a DBA (Direct Bonded Aluminum) substrate. Figure 1 The illustration is omitted, but Figure 2 As shown, the first insulating substrate 20 includes an insulating plate 21, a conductor 22 arranged on the first surface of the insulating plate 21, and a conductor 23 arranged on the second surface of the insulating plate 21. The insulating plate 21 is an insulating plate-shaped member arranged with the direction along the Z axis as the thickness direction. The insulating plate 21 is made of ceramics such as aluminum nitride, aluminum oxide or silicon nitride. The conductor 22 is a plate-shaped conductor arranged over substantially the entire area on the 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-shaped conductors that are appropriately divided. The conductor 22 and the conductor 23 are each made of a metal such as copper or aluminum.

[0031] The conductor 22 of each of the above first insulating substrates 20 is joined to a heat sink 40 using a joining material B0 such as solder. On the other hand, a plurality of semiconductor chips 30 are joined to the conductor 23 of each of the first insulating substrates 20 using a joining material such as solder. In this way, the first insulating substrate 20 is arranged on the first surface of the heat sink 40, and the semiconductor chip 30 is provided on the first insulating substrate 20. In addition, the number of semiconductor chips 30 mounted on each first insulating substrate 20 is arbitrary. In addition, the number of first insulating substrates 20 included in the semiconductor module 10 is not limited to Figure 1 In the example shown, the number may be less than two or more than four.

[0032] At least one of the plurality of semiconductor chips 30 mounted on the first insulating substrate 20 is a power semiconductor chip such as an IGBT. In addition, the first insulating substrate 20 may be equipped with a control chip for controlling the operation of the power semiconductor chip in addition to a switching element such as an IGBT as a semiconductor chip 30, and may also be equipped with an element such as a FWD (Free Wheeling Diode) for commutating a load current.

[0033] The heat sink 40 is a plate-shaped member for heat dissipation arranged along the direction of the Z axis as the thickness direction. The heat sink 40 is made of, for example, copper, copper alloy, aluminum or aluminum alloy. The heat sink 40 has high thermal conductivity and dissipates heat from the semiconductor chip 30. In addition, the heat sink 40 also has high electrical conductivity, for example, it is electrically connected to a reference potential such as a ground potential. In addition, the heat sink 40 is not limited to a metal plate as long as it has high thermal conductivity, and can also be an insulator such as ceramic. In addition, a heat sink or other heat dissipation member can be integrally provided on the surface of the heat sink 40 facing the Z2 direction.

[0034] exist Figure 1 In the example shown, when viewed in the direction along the Z axis, the heat sink 40 is configured to have 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. Mounting holes 41 are provided near each short side of the heat sink 40. The mounting holes 41 are, for example, through holes for screwing a heat sink or other heat dissipation member (not shown) to the heat sink 40. The top view shape and number of the heat sink 40 are not limited to Figure 1 The example shown is arbitrary. In addition, the mounting hole 41 is provided as required, and can also be omitted.

[0035] The housing 50 is a frame-shaped member that accommodates the plurality of first insulating substrates 20 and the plurality of semiconductor chips 30. Here, the housing 50 is arranged with the direction along the Z axis as the thickness direction, and forms a frame shape surrounding the plurality of first insulating substrates 20 when viewed from above. The housing 50 is a substantial insulator, and is made of a resin material such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene terephthalate). In addition, from the viewpoint of improving the mechanical strength of the housing 50 or reducing the linear expansion coefficient, the resin material may also contain an inorganic filler such as alumina or silica.

[0036] exist Figure 1In the example shown, when viewed in the direction along the Z axis, the housing 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. In addition, the housing 50 is provided with a plurality of holes 52 and a plurality of holes 53. The plurality of holes 52 are holes for screwing a substrate (not shown) on which the semiconductor module 10 is mounted to the housing 50. The plurality of holes 53 are through holes for screwing a heat dissipation member such as a heat sink (not shown) to the heat dissipation plate 40 together with the above-mentioned mounting holes 41. In addition, the shape of the housing 50 is not limited to Figure 1 The example shown is arbitrary. In addition, holes 52 and 53 are provided as required and can be omitted.

[0037] A plurality of external terminals 60 are fixed to the above housing 50. Here, the housing 50 is formed by insert molding each of the plurality of external terminals 60 as an insert. Thus, the external terminals 60 are firmly and stably fixed to the housing 50, so that, as described later, the external terminals 60 can be joined to the second insulating substrate 70 by being pressed in a state where they are fixed to the housing 50.

[0038] Each of the plurality of 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. Figure 2 As shown, each external terminal 60 is provided across the inside and outside of the housing 50 and is electrically connected to the semiconductor chip 30 by means of a bonding wire BW. The plurality of external terminals 60 are made of, for example, a metal such as copper, a copper alloy, aluminum, an aluminum alloy, or an iron alloy. In addition, the surface of the external terminal 60 may be plated, for example, with Sn or Sn-Cu.

[0039] Two or more external terminals 60 of the plurality of external terminals 60 included in the semiconductor module 10 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 .

[0040] The external terminal 60 is composed of a metal plate bent in a substantially L-shape. Figure 2 As shown, the external terminal 60 has a pin portion 61 , a leg portion 62 , a protrusion 63 , and a hole 64 .

[0041] The pin portion 61 is a part of the external terminal 60 and is a rod-shaped portion extending in the direction along the Z axis. The end of the pin portion 61 in the Z1 direction protrudes from the outer wall surface of the housing 50. In this way, the pin portion 61 has a terminal portion as a portion protruding from the outer wall surface of the housing 50. The terminal portion is connected to a substrate (not shown) on which the semiconductor module 10 is mounted. On the other hand, the leg portion 62 is connected to the end of the pin portion 61 in the Z2 direction. In addition, the shape of the pin portion 61 is not limited to Figure 1In the example shown, for example, the tip of the pin portion 61 may be branched into two parts.

[0042] The foot portion 62 is a part of the external terminal 60 and is a plate-shaped portion arranged along the surface of the second insulating substrate 70 facing the Z1 direction. The foot portion 62 extends from the end of the pin portion 61 in the Z2 direction toward the inside of the housing 50. The foot portion 62 has a portion sandwiched between the housing 50 and the second insulating substrate 70 and a plate portion that is exposed to the inside of the housing 50. The plate portion is joined to Figure 2 One end of the bonding wire BW is shown. The other end of the bonding wire BW is connected to the first insulating substrate 20 or the semiconductor chip 30. Through this connection, the external terminal 60 and the semiconductor chip 30 are electrically connected to each other.

[0043] The protrusion 63 is a part of the external terminal 60 and is a part protruding from the leg 62 toward the Z2 direction. The hole 64 is a hole provided along with the formation of the protrusion 63 when the external terminal 60 is formed by bending the metal plate. The details of the protrusion 63 and the hole 64 will be described later based on Figure 3 and Figure 4 Provide explanation.

[0044] The plurality of second insulating substrates 70 are disposed between the heat sink 40 and the plurality of external terminals 60, and are members having a higher thermal conductivity than that of the housing 50. Each second insulating substrate 70 is disposed with the direction along the Z axis as the thickness direction. In the present embodiment, the plurality of second insulating substrates 70 are separated corresponding to each external terminal, and the plurality of second insulating substrates 70 correspond to the plurality of external terminals 60 one-to-one. Therefore, the corresponding second insulating substrates 70 are interposed between the heat sink 40 and each external terminal 60. In addition, in addition to the plurality of second insulating substrates 70 corresponding to the plurality of external terminals 60, there may also be a second insulating substrate 70 that does not contribute to the bonding with the external terminals 60 but is interposed between the heat sink 40 and the housing 50.

[0045] 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, compared with a form in which the first insulating substrate 20 and the second insulating substrate 70 have different layer structures, the cost of the semiconductor module 10 can be reduced.

[0046] Specifically, Figure 1 and Figure 2As shown, the second insulating substrate 70 includes an insulating plate 71, a first conductor 72 disposed on the first surface of the insulating plate 71, and a second conductor 73 disposed on the second surface of the insulating plate 71. The insulating plate 71 is an insulating plate-shaped member disposed with the direction of the Z axis as the thickness direction. The insulating plate 71 is made of ceramics such as aluminum nitride, aluminum oxide, or silicon nitride, for example. The first conductor 72 is a plate-shaped conductor disposed over substantially the entire area on the surface of the insulating plate 71 facing the Z2 direction, and is bonded to the first surface of the heat sink 40 using a bonding material B1 described later. The second conductor 73 is a plate-shaped conductor disposed over substantially the entire area on the surface of the insulating plate 71 facing the Z1 direction, and is separated corresponding to each of the plurality of external terminals 60. However, a notch 73a is provided in the second conductor 73. The first conductor 72 and the second conductor 73 are each made of a metal such as copper or aluminum, for example.

[0047] Here, the notch 73a constitutes a recessed portion 74 for receiving the press-fit of the protrusion 63. Thus, the plurality of external terminals 60 are respectively joined to the plurality of second insulating substrates 70 by press-fitting. The details of the recessed portion 74 will be described later based on Figure 3 and Figure 4 Provide explanation.

[0048] 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, and may be, for example, lead-free solder such as SnAg, SnAgCu, SnBi, SnZnBi, SnCu, SnAgBi, SnSb, or SnZnAl. In this way, the plurality of second insulating substrates 70 and the first surface of the heat sink 40 are bonded to each other by a thermally conductive bonding material B1. In addition, the bonding material B1 is not limited to solder, and may be, for example, an adhesive such as an epoxy adhesive containing an inorganic filler such as silica or alumina, an acrylic adhesive, a polyurethane adhesive, or a silicone adhesive.

[0049] Here, the heat sink 40 and the housing 50 are bonded by adhesive B2. Adhesive B2 is an insulating adhesive. More specifically, adhesive B2 is, for example, an epoxy adhesive, an acrylic adhesive, a polyurethane adhesive, or a silicone adhesive. Adhesive B2 may also contain an insulating inorganic filler such as alumina or silica. Figure 5 Provide explanation.

[0050] The cover 80 is a plate-shaped member joined to the surface of the housing 50 facing the Z1 direction. The cover 80 is made of a resin material such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene terephthalate) as with the housing 50. The cover 80 is joined to the housing 50 by an adhesive or the like in such a way that a gap between the cover 80 and the housing 50 is sealed.

[0051] Here, if Figure 2 As shown, a space surrounded by the heat sink 40, the housing 50 and the cover 80 is filled with a potting material PA covering the semiconductor chip 30. The potting material PA is made of, for example, silicone resin such as silicone gel.

[0052] In the above schematic semiconductor module 10, each external terminal 60 is connected to the heat sink 40 via the second insulating substrate 70 having a higher thermal conductivity than the housing 50, so that the Joule heat generated in the bonding wire BW and the external terminal 60 can be discharged to the heat sink 40 via the second insulating substrate 70. Here, since the second insulating substrate 70 and the heat sink 40 are bonded to each other by the bonding material B1 having a high thermal conductivity, the thermal resistance between the second insulating substrate 70 and the heat sink 40 can be reduced. In addition, since the external terminal 60 and the second insulating substrate 70 are bonded to each other by press-fitting, the external terminal 60 and the second insulating substrate 70 can be easily assembled, and the thermal resistance between the external terminal 60 and the second insulating substrate 70 can be reduced. As described above, the temperature rise of the external terminal 60 and the bonding wire BW can be suppressed.

[0053] 1-2. External Terminals and Second Insulating Substrate

[0054] Figure 3 It is a perspective view of the external terminal 60 in the first embodiment. Figure 4 1 is a diagram for explaining the bonding between the external terminal 60 and the second insulating substrate 70 in the first embodiment. Figure 3 and Figure 4 As shown, the external terminal 60 has a shape bent along a straight line LN along a boundary between the pin portion 61 and the leg portion 62 and is integrally formed by bending a metal plate or the like.

[0055] In this way, each of the plurality of external terminals 60 is formed by bending a metal plate, and thus, compared with a configuration in which the external terminals 60 are manufactured by welding or the like, it is possible to reduce the cost of the semiconductor module 10 .

[0056] The protrusion 63 protrudes from the leg portion 62 toward the Z2 direction. Figure 3 and Figure 4In the example shown, the protrusion 63 is arranged 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 the bending process of the metal plate.

[0057] In this way, each of the plurality of external terminals 60 has the protrusion 63 that protrudes toward the second insulating substrate 70 .

[0058] On the other hand, the concave portion 74 of the second insulating substrate 70 is a recessed portion that opens toward the Z1 direction. Figure 4 In the example shown, the recessed portion 74 is formed using the notch 73a provided in the second conductor 73. Here, the recessed portion 74 includes a wall surface formed by the notch 73a and a bottom surface formed by a surface of the insulating plate 71 facing the Z1 direction.

[0059] In this way, each second insulating substrate 70 has a recessed portion 74 that fits with the protrusion 63 by being pressed in. Therefore, compared with a configuration in which the recessed portion 74 provided in the external terminal 60 and the protrusion provided in the second insulating substrate 70 are joined by being pressed in, it is easy to make the hole 64 smaller than the notch 66 of the modified example 1 described later, thereby having the advantage of being easy to increase the contact area between the external terminal 60 and the second insulating substrate 70.

[0060] In addition, by forming the recess 74 using a notch that passes through the second conductor 73, the external terminal 60 and the second insulating substrate 70 can be easily joined to each other by press-fitting. In addition, the second conductor 73 may have a hole that passes through the second conductor 73. In this case, the recess 74 may be formed using the hole instead of the notch 73a.

[0061] As described above, the layer structure of the second insulating substrate 70 is the same as that of the first insulating substrate 20. Specifically, the insulating plate 71 of the second insulating substrate 70 is made of the same thickness and material as the insulating plate 21 of the first insulating substrate 20. In addition, the first conductor 72 of the second insulating substrate 70 is made of the same thickness and material as the conductor 22 of the first insulating substrate 20. Furthermore, the second conductor 73 of the second insulating substrate 70 is made of the same thickness and material as the conductor 23 of the first insulating substrate 20.

[0062] The protrusion 63 is pressed into the recess 74. Thus, the external terminal 60 and the second insulating substrate 70 are bonded to each other.

[0063] Here, the second conductor 73 is separated corresponding to each external terminal 60, so that the external terminals 60 are prevented from being electrically connected to each other, and the external terminal 60 and the second conductor 73 are joined by press-fitting. In addition, since there are a plurality of second insulating substrates 70, the thermal stress between the second insulating substrate 70 and the housing 50 can be reduced compared to a configuration in which there is only one second insulating substrate 70.

[0064] In addition, the plurality of second insulating substrates 70 are separated corresponding to each external terminal 60. Therefore, the second insulating substrate 70 can be shared between semiconductor modules 10 having different arrangements of the external terminals 60. As a result, the cost of the semiconductor module 10 can be reduced.

[0065] Each of the plurality of 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 that fits with the protrusion 63 by press-fitting. Therefore, compared with a form 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 that the contact area between the external terminal 60 and the second insulating substrate 70 can be easily increased.

[0066] The width W2 of the recess 74 is larger than the width W1 of the protrusion 63 in such a manner that there is an interference amount that allows the protrusion 63 to be pressed into the recess 74. The interference amount is in the range of 0.04 mm to 0.18 mm. 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. Figure 3 and Figure 4 In the example shown, the widths of the protrusion 63 and the recess 74 are constant. In addition, the width of the protrusion 63 may not be constant. For example, the protrusion 63 may have a tapered surface in a manner that the width decreases as it goes in the Z2 direction. In addition, the width of the recess 74 may not be constant. For example, the recess 74 may have a tapered surface in a manner that the width increases as it goes in the Z1 direction.

[0067] The protruding length L1 of the protrusion 63 is less than the depth D1 of the recess 74, that is, the thickness t of the second conductor 73. Therefore, it is not necessary to perform processing for forming the recess 74 on the insulating plate 71, so that the second insulating substrate 70 can be easily manufactured. In addition, the portion of the protrusion 63 up to the root can be pressed into the recess 74. 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. Thus, by increasing the contact area between the external terminal 60 and the second insulating substrate 70, the thermal resistance between the external terminal 60 and the second insulating substrate 70 can be reduced.

[0068] In addition, a gap may be formed between the external terminal 60 and the second insulating substrate 70. In this case, it is preferable to provide a heat transfer material such as an adhesive or grease having excellent thermal conductivity in the gap.

[0069] 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 by a bonding material B1 having excellent thermal conductivity. The bonding material B1 is, for example, solder. Thus, the heat sink 40 and the second insulating substrate 70 can be firmly bonded by the bonding material B1, and the thermal resistance between the heat sink 40 and the second insulating substrate 70 can be reduced.

[0070] The solder is not particularly limited, and may be lead-free solders such as SnAg, SnAgCu, SnBi, SnZnBi, SnCu, SnAgBi, SnSb, or SnZnAl. In addition, 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 polyurethane adhesive, or a silicone adhesive containing inorganic fillers such as silica or alumina.

[0071] Here, the heat sink 40 and the housing 50 are bonded together using an adhesive B2.

[0072] Figure 5 FIG. 4 is a bottom view of the housing 50 to which a plurality of external terminals 60 are fixed. Figure 5 , the housing 50 is shown together with the plurality of external terminals 60 when viewed in the Z1 direction.

[0073] like Figure 5 As shown, a plurality of leg portions 62 of external terminals 60 are arranged on the bottom surface of the housing 50 , that is, on the surface of the housing 50 facing the Z2 direction.

[0074] like Figure 5 As shown, the adhesive B2 is provided over the entire periphery of the heat sink 40. Here, the adhesive B2 is arranged in a manner avoiding the leg 62 of the external terminal 60, and has a plurality of portions B2a and portions B2b. The portion B2a is a portion of the adhesive B2, and is a portion for joining the surface of the heat sink 40 facing the Z1 direction to the housing 50, and the portion B2a is arranged in a manner avoiding the leg 62 of the external terminal 60. The portion B2b is a portion of the adhesive B2, and is a portion for joining the side surface of the heat sink 40 to the housing 50, and the portion B2b is arranged over the entire periphery of the side surface of the heat sink 40.

[0075] In this way, the case 50 and the heat sink 40 are bonded to each other by the adhesive B2. Therefore, the insulation between the external terminal 60 and the heat sink 40 can be ensured, and the gap between the case 50 and the heat sink 40 can be sealed by the adhesive B2.

[0076] In addition, the adhesive B2 may be in contact with the external terminal 60 or the second insulating substrate 70. That is, the adhesive B2 may not only bond the heat sink 40 and the housing 50 to each other, but may also bond one or both of the leg portion 62 of the external terminal 60 and the second insulating substrate 70 to the heat sink 40 and the housing 50.

[0077] As described above, in the semiconductor module 10 , it is possible to suppress the temperature increase of the external terminals 60 and the bonding wires BW.

[0078] 2. Second Implementation Method

[0079] In the following exemplary embodiments, elements having the same effects and functions as those in the above-described embodiments are assigned the same reference numerals as those in the above-described embodiments, and detailed descriptions thereof are appropriately omitted.

[0080] Figure 6 1 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 according to the first embodiment, except that it includes a single second insulating substrate 70A instead of the plurality of second insulating substrates 70 according to the first embodiment.

[0081] The second insulating substrate 70A has the same configuration as the second insulating substrate 70 of the first embodiment except that it includes one insulating plate 71A and one first conductor 72A instead of the plurality of insulating plates 71 and the plurality of first conductors 72 of the first embodiment.

[0082] The insulating plate 71A is configured similarly to the insulating plate 71 of the first embodiment except that it is formed in a frame shape along 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 circumferential region of the insulating plate 71A.

[0083] The above second embodiment can also suppress the temperature rise of the external terminal 60 and the bonding wire BW. In this embodiment, a plurality of second conductors 73 corresponding to each external terminal 60 are arranged on the surface of the insulating plate 71A of one second insulating substrate 70A. Therefore, the second insulating substrate 70A can be easily positioned 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.

[0084] 3. Modifications

[0085] The present disclosure is not limited to the above-described embodiments, and various modifications described below are possible. In addition, the embodiments and modifications may be appropriately combined.

[0086] 3-1. Modification 1

[0087] Figure 7 It is a perspective view of the external terminal 60B in the first modification. Figure 8 This is a diagram for explaining the bonding between the external terminal 60B and the second insulating substrate 70B in the first modification.

[0088] like Figure 7 and Figure 8 As shown, the external terminal 60B has a pin portion 61 , a leg portion 62 , a recess 65 , and a notch 66 .

[0089] The recess 65 is a part of the external terminal 60B and is a recessed portion that opens from the leg portion 62 toward the Z2 direction. The notch 66 is a missing portion that is provided along with the formation of the recess 65 when the external terminal 60B is formed by bending a metal plate. Figure 7 and Figure 8 The examples shown are rather arbitrary.

[0090] 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 convex portion 75 that receives the depression 65. The shape of the portion 73b is not limited to Figure 7 and Figure 8 The examples shown are rather arbitrary.

[0091] According to the above-described first modification, it is also possible to suppress the temperature increase of the external terminal 60B and the bonding wire BW.

[0092] 3-2. Modification 2

[0093] In the above-mentioned embodiment, the layer structure of the second insulating substrate 70, 70A, 70B is the same as the layer structure of the first insulating substrate 20, but the present invention is not limited to this form, and a second insulating substrate having a layer structure different from the layer structure of the first insulating substrate 20 may be used. For example, the thickness and number of layers of each layer of the second insulating substrate may be different from those of the first insulating substrate 20.

[0094] 3-3. Modification 3

[0095] In the first embodiment described above, an insulating plate 71 is provided corresponding to each external terminal 60, but the insulating plate 71 may be integrally formed corresponding to each of the plurality of external terminals 60. Here, for example, the insulating plates 71 corresponding to two external terminals 60 and the insulating plates 71 corresponding to one external terminal 60 may be mixed.

[0096] 4. Notes

[0097] According to the above-mentioned embodiment and modification examples, for example, the following aspects can be understood.

[0098] (Supplementary Note 1) The first form of the semiconductor module disclosed in the present invention comprises: a heat sink; a first insulating substrate, which is arranged on the first surface of the heat sink, and a semiconductor chip is provided on the first insulating substrate; a frame-shaped shell, which surrounds the first insulating substrate; a plurality of external terminals, which are arranged across the inside and outside of the shell and are electrically connected to the semiconductor chip by means of bonding wires; and at least one second insulating substrate, which is arranged between the heat sink and the plurality of external terminals and has a thermal conductivity higher than that of the shell, the at least one second insulating substrate and the first surface of the heat sink are bonded to each other by using a thermally conductive bonding material, and the plurality of external terminals are each bonded to the at least one second insulating substrate by pressing.

[0099] In the above form, each external terminal is connected to the heat sink by means of a second insulating substrate having a higher thermal conductivity than that of the housing, so that the Joule heat generated in the bonding wire and the external terminal can be discharged to the heat sink by means of the second insulating substrate. Here, the second insulating substrate and the heat sink are bonded to each other using 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, since the external terminal and the second insulating substrate are bonded to each other by pressing, the external terminal and the second insulating substrate can be easily assembled, and the thermal resistance between the external terminal and the second insulating substrate can be reduced. As described above, the temperature rise of the external terminal and the bonding wire can be suppressed.

[0100] (Supplementary Note 2) In a second form as a preferred example of the first form, the at least one second insulating substrate is a plurality of second insulating substrates, each of the plurality of second insulating substrates having: an insulating plate; a first conductor disposed on the first surface of the insulating plate and bonded to the first surface of the heat sink by the bonding material; and at least one second conductor disposed on the second surface of the insulating plate, the at least one second conductor being separated corresponding to each of the plurality of external terminals. In the above form, the second insulating substrate has the insulating plate, the first conductor, and the second conductor, so that 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, the second conductor is separated corresponding to each external terminal, so that conduction between the external terminals can be prevented, and the external terminal and the second conductor can be bonded by pressing. In addition, since the number of the second insulating substrates is plural, the thermal stress between the second insulating substrate and the housing can be reduced compared to the form in which the number of the second insulating substrate is one.

[0101] (Supplementary Note 3) In a third aspect which is a preferred example of the second aspect, the plurality of second insulating substrates are separated corresponding to each of the plurality of external terminals. In the above aspect, the second insulating substrate can be shared by semiconductor modules having different arrangements of external terminals. As a result, the cost of the semiconductor module can be reduced.

[0102] (Supplementary Note 4) In the fourth form as a preferred example of the first form, the at least one second insulating substrate is a second insulating substrate, and the second insulating substrate has: an insulating plate; a first conductor, which is arranged on the first surface of the insulating plate and is bonded to the first surface of the heat sink by the bonding material; and a plurality of second conductors, which are arranged on the second surface of the insulating plate and are separated corresponding to each of the plurality of external terminals. In the above form, the second insulating substrate has an insulating plate, a first conductor and a second conductor, so a substrate such as a DCB substrate or a DBA substrate can be used as the second insulating substrate. Here, a plurality of second conductors corresponding to each external terminal are arranged on the surface of the insulating plate of a second insulating substrate, so that the second insulating substrate can be easily positioned relative to the heat sink. 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.

[0103] (Supplementary Note 5) In the fifth form which is a preferred example of any one of the first to fourth forms, the housing and the heat sink are bonded to each other using an adhesive. In the above form, the insulation between the external terminal and the heat sink can be ensured, and the gap between the housing and the heat sink can be sealed using the adhesive.

[0104] (Supplementary 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, compared with a method in which the first insulating substrate and the second insulating substrate have different layer structures, it is possible to achieve a low cost of the semiconductor module.

[0105] (Supplementary Note 7) In the seventh form which is a preferred example of any one of the first to sixth forms, 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 recessed portion that fits with the protrusion by pressing in. In the above form, compared with a form in which the recessed portion provided in the external terminal and the protruding portion provided in the second insulating substrate are joined by pressing in, there is an advantage that the contact area between the external terminal and the second insulating substrate can be easily increased.

[0106] (Supplementary Note 8) In an eighth aspect as a preferred example of the seventh aspect, the recess includes a hole or a notch that penetrates 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.

[0107] (Supplementary Note 9) In the ninth aspect which is a preferred example of the seventh aspect or the eighth aspect, the protrusion has a protruding length that is less than or equal to the thickness of the second conductor of the at least one second insulating substrate. In the above aspect, there is no need to perform processing for forming a recess in the insulating plate, so the second insulating substrate can be easily manufactured.

[0108] (Supplementary Note 10) In the tenth form which is a preferred example of any one of the first to ninth forms, each of the plurality of external terminals is formed by bending a metal plate. In the above form, compared with a form in which the external terminals are manufactured by welding or the like, it is possible to achieve low cost of the semiconductor module.

[0109] (Supplementary Note 11) In the 11th form which is a preferred example of any one of the 1st to 10th forms, the bonding material is solder. In the above forms, the heat sink and the second insulating substrate can be firmly bonded by the bonding material, and the thermal resistance between the heat sink and the second insulating substrate can be reduced.

[0110] (Supplementary Note 12) In the twelfth form which is a preferred example of any one of the first to eleventh forms, the housing is formed by insert molding each of the plurality of external terminals as an insert. In the above forms, since the external terminals are firmly and stably fixed to the housing, the external terminals can be joined to the second insulating substrate by being pressed in a state where they are fixed to the housing.

Claims

1. A semiconductor module, wherein: The semiconductor module has: Heat sink; a first insulating substrate disposed on the first surface of the heat sink, on which a semiconductor chip is provided; A frame-shaped housing surrounding the first insulating substrate; A plurality of external terminals, which are arranged across the inside and outside of the housing and are electrically connected to the semiconductor chip by bonding wires; as well as at least one second insulating substrate, which is disposed between the heat sink and the plurality of external terminals and has a thermal conductivity higher than that of the housing, The at least one second insulating substrate and the first surface of the heat sink are bonded to each other using 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.

2. The semiconductor module according to claim 1, wherein: The at least one second insulating substrate is a plurality of second insulating substrates, Each of the plurality of second insulating substrates has: Insulation panels; a first conductor disposed on the first surface of the insulating plate and bonded to the first surface of the heat sink by the bonding material; as well as At least one second conductor is disposed on the second surface of the insulating plate, and the at least one second conductor is separated corresponding to each of the plurality of external terminals.

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

4. The semiconductor module according to claim 1, wherein: The at least one second insulating substrate is a second insulating substrate, The second insulating substrate comprises: Insulation panels; a first conductor disposed on the first surface of the insulating plate and bonded to the first surface of the heat sink by the bonding material; as well as A plurality of second conductors are disposed on the second surface of the insulating plate, and the plurality of second conductors are separated corresponding to each of the plurality of external terminals.

5. The semiconductor module according to claim 2 or 4, wherein: The housing and the heat sink are bonded to each other using an adhesive.

6. The semiconductor module according to claim 2 or 4, wherein: The at least one second insulating substrate has the same layer structure as the first insulating substrate.

7. The semiconductor module according to claim 2 or 4, wherein: Each of the plurality of external terminals has a protrusion protruding toward the at least one second insulating substrate, The at least one second insulating substrate has a recessed portion that fits with the protrusion by press-fitting.

8. The semiconductor module according to claim 7, wherein: The recess includes a hole or a notch that passes through the second conductor of the at least one second insulating substrate.

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

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

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

12. The semiconductor module according to claim 1, wherein The housing is formed by insert molding in which each of the plurality of external terminals is an insert part.

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