Semiconductor equipment

Abstract

To provide a semiconductor device that can exhibit more stable performance under high temperature and high humidity conditions. [Solution] The semiconductor device A12 comprises a first conductive layer having a main surface facing one side in the thickness direction z, a first bonding layer 391 disposed on the main surface and being a conductor, a first element having a first surface, a second surface and a third surface, with the second surface being bonded to the main surface via the first bonding layer 391, a conductive member electrically connected to the first surface, and a first insulating layer covering at least the first surface and the third surface. The first bonding layer 391 extends from the main surface to the second surface and has sides that define the outer shape of the first bonding layer. The first insulating layer is in contact with the main surface and the sides. In a cross-section with the thickness direction z as the in-plane direction, the first insulating layer straddles the boundary between the main surface and the sides.

Description

[Technical Field]

[0001] This invention relates to a semiconductor device. [Background technology]

[0002] Patent Document 1 discloses an example of a semiconductor device in which multiple switching elements, such as MOSFETs, are electrically joined. The semiconductor device comprises a case made of synthetic resin and a wiring board supported by the case. The multiple switching elements are electrically joined to the wiring board. The area surrounded by the case and the wiring board is filled with a sealing resin made of silicone gel or the like. The multiple switching elements are covered with the sealing resin.

[0003] In recent years, there has been a growing demand for semiconductor devices with relatively high rated voltages in tropical climates near the equator. Such semiconductor devices are typically placed in environments characterized by high temperature and humidity. To ensure more stable performance under these conditions, it is desirable for semiconductor devices to pass the H3TRB (High Humidity High Temperature Reverse Bias Test). The H3TRB test measures the operating endurance time (in hours) of a semiconductor device when driven at 80% of its rated voltage under high temperature and high humidity conditions (85°C, 85% humidity). A semiconductor device passes the H3TRB test if its operating endurance time is 1,000 hours or more. Semiconductor devices that pass this test are expected to exhibit more stable performance under high temperature and high humidity conditions.

[0004] The inventors have confirmed that, based on H3TRB testing of semiconductor devices such as those disclosed in Patent Document 1, the device endurance time for operation of such semiconductor devices is likely to be less than 1,000 hours. When moisture penetrates the encapsulating resin in such semiconductor devices placed under high temperature and high humidity conditions, the dielectric strength of the encapsulating resin decreases, which can cause leakage current to occur in multiple switching elements. When the leakage current reaches the wiring board, multiple switching elements are destroyed, resulting in a shorter device endurance time. The higher the rated voltage required for a semiconductor device, the shorter the device endurance time tends to be. For these reasons, passing the H3TRB test corresponding to the required rated voltage is one indicator that a semiconductor device can exhibit more stable performance under high temperature and high humidity conditions. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-139691 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In view of the above circumstances, the object of the present invention is to provide a semiconductor device that can exhibit more stable performance under high temperature and high humidity conditions. [Means for solving the problem]

[0007] According to the present invention, a semiconductor device is provided comprising: a substrate having a main surface facing the thickness direction; a conductive mounting layer disposed on the main surface; a plurality of switching elements having a first element main surface facing the side of the main surface in the thickness direction, a first element back surface facing the opposite side of the first element main surface, and a first element side surface connected to both the first element main surface and the first element back surface, and electrically joined to the mounting layer with the first element back surface facing the main surface; a moisture-resistant layer covering at least one of the first element side surfaces; and a sealing resin covering both the plurality of switching elements and the moisture-resistant layer, wherein the moisture-resistant layer is in contact with both the mounting layer and the first element side surface so as to straddle the space between the mounting layer and the first element side surface in the thickness direction.

[0008] Preferably, in the implementation of the present invention, the sealing resin is a silicone gel.

[0009] Preferably in the implementation of the present invention, the moisture-resistant layer contains polyimide.

[0010] Preferably in the implementation of the present invention, the moisture-resistant layer comprises a silicone gel.

[0011] Preferably in the implementation of the present invention, the upper arm mounting layer and the lower arm mounting layer are spaced apart from each other in a first direction perpendicular to the thickness direction, and the plurality of switching elements are electrically connected to both the upper arm mounting layer and the lower arm mounting layer, and in each of the upper arm mounting layer and the lower arm mounting layer, the plurality of switching elements are arranged in a second direction perpendicular to both the thickness direction and the first direction.

[0012] Preferably in the implementation of the present invention, each of the plurality of switching elements has a main surface electrode provided on the main surface of the first element and an insulating film provided on the main surface of the first element and surrounding the main surface electrode when viewed in the thickness direction, and the moisture-resistant layer is in contact with both the side surface of the first element and the insulating film such that it straddles the periphery of the insulating film when viewed in the thickness direction.

[0013] Preferably in the implementation of the present invention, the moisture-resistant layer is in contact with at least a portion of the main surface electrode.

[0014] Preferably in carrying out the present invention, the device further comprises a conductive layer disposed on the main surface and located in the first direction opposite to the upper arm mounting layer with respect to the lower arm mounting layer, the main surface electrode, and a plurality of wires connected to either the lower arm mounting layer or the conductive layer, each of the plurality of wires having a first bonding portion in contact with the main surface electrode, and the moisture-resistant layer in contact with at least a portion of the first bonding portion.

[0015] Preferably in the implementation of the present invention, the plurality of wires extend in the first direction.

[0016] Preferably in the implementation of the present invention, each of the plurality of main surface electrodes has a pair of first pad portions spaced apart from each other in the second direction, and a pair of second pad portions spaced apart from each other in the second direction and located on the opposite side of the pair of first pad portions from either the lower arm mounting layer or the conductive layer in the first direction, and in each of the plurality of switching elements, the plurality of wires includes a pair of inner wires whose first bonding portion is in contact with the pair of first pad portions, and a pair of outer wires whose first bonding portion is in contact with both the pair of first pad portions and the pair of second pad portions, and the pair of outer wires is arranged on both sides of the pair of inner wires in the second direction.

[0017] Preferably in the implementation of the present invention, each of the pair of outer wires of the first bonding portion has a first connecting portion in contact with the first pad portion, a second connecting portion in contact with the second pad portion, and a connecting portion sandwiched between the first connecting portion and the second connecting portion in the first direction, wherein the connecting portion protrudes toward the side facing the main surface of the first element in the thickness direction.

[0018] In the implementation of the present invention, preferably, a plurality of protection elements are further provided which are electrically joined to both the upper arm mounting layer and the lower arm mounting layer and are individually conductive to the plurality of main surface electrodes. Each of the plurality of protection elements has a second element main surface facing the side where the main surface faces in the thickness direction, and an anode electrode provided on the second element main surface, and at least one of the plurality of wires connected to the main surface electrode is connected to the anode electrode.

[0019] In the implementation of the present invention, preferably, the moisture-resistant layer covers the plurality of protection elements.

[0020] In the implementation of the present invention, preferably, the substrate includes a first substrate and a second substrate spaced apart from each other in the second direction. On the main surface of each of the first substrate and the second substrate, regions of the upper arm mounting layer, the lower arm mounting layer, and the conductive layer are arranged. A first power terminal conductive to the region of the upper arm mounting layer arranged on the first substrate, a second power terminal conductive to the region of the conductive layer arranged on the first substrate, and an output terminal conductive to the region of the lower arm mounting layer arranged on the second substrate are further provided.

[0021] In the implementation of the present invention, preferably, it includes a first member, a second member, and a third member, and further includes a relay conductive member extending in the second direction. The region of the upper arm mounting layer arranged on the first substrate and the region of the upper arm mounting layer arranged on the second substrate are mutually conductive through the first member. The region of the lower arm mounting layer arranged on the first substrate and the region of the lower arm mounting layer arranged on the second substrate are mutually conductive through the second member. The region of the conductive layer arranged on the first substrate and the region of the conductive layer arranged on the second substrate are mutually conductive through the third member.

[0022] In the implementation of the present invention, preferably, each of the first substrate and the second substrate has a back surface facing the opposite side of the main surface in the thickness direction, and further includes a heat sink joined to both the back surface of the first substrate and the back surface of the second substrate.

[0023] In the implementation of the present invention, preferably, it further includes a frame-shaped case surrounding the periphery of the substrate as viewed from the thickness direction, and the first power terminal, the second power terminal, the output terminal, and the heat sink are supported by the case, and the encapsulation resin is accommodated in the region surrounded by the case and the heat sink.

Effects of the Invention

[0024] According to the semiconductor device of the present invention, it is possible to exhibit stable performance under high temperature and high humidity.

[0025] Other features and advantages of the present invention will become clearer from the detailed description given below based on the accompanying drawings.

Brief Description of the Drawings

[0026] [Figure 1] It is a perspective view of a semiconductor device according to a first embodiment of the present invention. [Figure 2] It is a plan view of the semiconductor device shown in FIG. 1. [Figure 3] It is a plan view of the semiconductor device shown in FIG. 1 (transmitting through the encapsulation resin, moisture-resistant layer, and top plate). [Figure 4] It is a front view of the semiconductor device shown in FIG. 1. [Figure 5] It is a right side view of the semiconductor device shown in FIG. 1. [Figure 6] It is a left side view of the semiconductor device shown in FIG. 1. [Figure 7] It is a bottom view of the semiconductor device shown in FIG. 1. [Figure 8] It is a right enlarged view of FIG. 3 (periphery of the first substrate). [Figure 9] It is a left enlarged view of FIG. 3 (periphery of the second substrate). [Figure 10] This is a magnified view of the center of Figure 3 (around the third substrate). [Figure 11] This is a cross-sectional view along the line XI-XI in Figure 3. [Figure 12] This is a cross-sectional view along the line XII-XII in Figure 3. [Figure 13] This is a cross-sectional view along the line XIII-XIII in Figure 3. [Figure 14] This is a cross-sectional view along the line XIV-XIV in Figure 3. [Figure 15] Figure 3 is a magnified view of a portion of it (showing the switching element and protective element bonded to the upper arm mounting layer, respectively). [Figure 16] This is a cross-sectional view along the line XVI-XVI in Figure 15. [Figure 17] This is a cross-sectional view along the line XVII-XVII in Figure 15. [Figure 18] Figure 3 is a magnified view of a portion of it (showing the switching element and protective element bonded to the lower arm mounting layer, respectively). [Figure 19] This is a cross-sectional view along the line XIX-XIX in Figure 18. [Figure 20] This is a cross-sectional view along the line XX-XX in Figure 18. [Figure 21] Figure 1 is a circuit diagram of the semiconductor device shown. [Figure 22] This is a magnified section of Figure 16. [Figure 23] This is a partially enlarged cross-sectional view of the semiconductor device of the comparative example (switching element bonded to the upper arm layer). [Figure 24] This is a partially enlarged cross-sectional view of a semiconductor device according to a first modification of the first embodiment of the present invention (a switching element and a protective element bonded to the upper arm layer, respectively). [Figure 25] This is a partially enlarged cross-sectional view of a semiconductor device according to a first modification of the first embodiment of the present invention (a switching element and a protective element bonded to the lower arm layer, respectively). [Figure 26] This is a partially enlarged plan view of a semiconductor device according to a second modification of the first embodiment of the present invention (a switching element and a protective element bonded to the upper arm mounting layer, respectively). [Figure 27] This is a cross-sectional view along the line XXVII-XXVII in Figure 26. [Figure 28] This is a cross-sectional view along the line XXVIII-XXVIII in Figure 26. [Figure 29] This is a partially enlarged plan view of a semiconductor device according to a second modification of the first embodiment of the present invention (a switching element and a protective element bonded to the lower arm mounting layer, respectively). [Figure 30] This is a cross-sectional view along the line XXX-XXX in Figure 29. [Figure 31] This is a cross-sectional view along the line XXXX-XXXI in Figure 29. [Figure 32] This is a partially enlarged plan view of a semiconductor device according to a third modification of the first embodiment of the present invention (a switching element and a protective element bonded to the upper arm mounting layer, respectively). [Figure 33] This is a cross-sectional view along the line XXXIII-XXXIII in Figure 32. [Figure 34] This is a cross-sectional view along the line XXXIV-XXXIV in Figure 32. [Figure 35] This is a partially enlarged plan view of a semiconductor device according to a third modification of the first embodiment of the present invention (a switching element and a protective element bonded to the lower arm mounting layer, respectively). [Figure 36] This is a cross-sectional view along the line XXXVI-XXXVI in Figure 35. [Figure 37] This is a cross-sectional view along the line XXXVII-XXXVII in Figure 35. [Figure 38] This is a partially enlarged plan view of a semiconductor device according to a fourth modification of the first embodiment of the present invention (a switching element and a protective element bonded to the upper arm mounting layer, respectively). [Figure 39] This is a cross-sectional view along the line XXXIX-XXXIX in Figure 38. [Figure 40] This is a cross-sectional view along the XL-XL line in Figure 38. [Figure 41] This is a partially enlarged plan view of a semiconductor device according to a fourth modification of the first embodiment of the present invention (a switching element and a protective element bonded to the lower arm mounting layer, respectively). [Figure 42] This is a cross-sectional view along the line XLII-XLII in Figure 41. [Figure 43] This is a cross-sectional view along the line XLIII-XLIII in Figure 41. [Figure 44] This is a partially enlarged plan view of a semiconductor device according to a fifth modification of the first embodiment of the present invention (a switching element and a protective element bonded to the upper arm mounting layer, respectively). [Figure 45] This is a cross-sectional view along the XLV-XLV line in Figure 44. [Figure 46] This is a cross-sectional view along the XLVI-XLVI line in Figure 45. [Figure 47] This is a partially enlarged plan view of a semiconductor device according to a fifth modification of the first embodiment of the present invention (a switching element and a protective element bonded to the lower arm mounting layer, respectively). [Figure 48] This is a cross-sectional view along the line XLVIII-XLVIII in Figure 47. [Figure 49] This is a cross-sectional view along the XLIX-XLIX line in Figure 47. [Figure 50] These are the results of various tests based on differences in the thickness of the moisture-resistant layer of a semiconductor device according to a fourth modification of the first embodiment of the present invention. [Figure 51] This shows the H3TRB test results for a semiconductor device according to the fourth modification of the first embodiment of the present invention and a semiconductor device of a comparative example. [Figure 52] This is a partially enlarged plan view of a semiconductor device according to a second embodiment of the present invention (a switching element and a protective element bonded to the upper arm mounting layer, respectively). [Figure 53] This is a cross-sectional view along the line LIII-LIII in Figure 52. [Figure 54] This is a cross-sectional view along the LIV-LIV line in Figure 52. [Figure 55] This is a partially enlarged plan view of a semiconductor device according to a second embodiment of the present invention (a switching element and a protective element bonded to the lower arm mounting layer, respectively). [Figure 56] This is a cross-sectional view along the LVI-LVI line in Figure 55. [Figure 57]This is a cross-sectional view along the LVII-LVII line in Figure 55. [Modes for carrying out the invention]

[0027] Embodiments for carrying out the present invention will be described with reference to the attached drawings.

[0028] [First Embodiment] A semiconductor device A10 according to a first embodiment of the present invention will be described based on Figures 1 to 23. The semiconductor device A10 comprises a substrate 11, a first mounting layer 211, a second mounting layer 221, a third mounting layer 231, a plurality of switching elements 31, a moisture-resistant layer 51, and a sealing resin 52. Of these, the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 are examples of "mounting layers" as described in the claims of the present invention. In addition to these, the semiconductor device A10 further comprises a first conductive layer 212, a second conductive layer 222, a third conductive layer 232, a power terminal 24, an output terminal 25, a relay conductive member 261, a plurality of protective elements 32, a plurality of wires 41, a heat sink 61, and a case 70. Of these, the first conductive layer 212, the second conductive layer 222, and the third conductive layer 232 are examples of "conductive layers" as described in the claims of the present invention. The power terminal 24 has a first power terminal 24A and a second power terminal 24B. For ease of understanding, Figure 3 shows the moisture-resistant layer 51, sealing resin 52, and top plate 79 passing through. In Figure 3, the XI-XI line and XII-XII line are shown as dashed lines. Also, the moisture-resistant layer 51 is not shown in Figures 11 and 12.

[0029] The semiconductor device A10 shown in Figure 1 is a power module. The semiconductor device A10 is used, for example, in inverter devices for various electrical products. As shown in Figures 1 and 2, the semiconductor device A10 is rectangular when viewed from the thickness direction z of the substrate 11. Here, for the sake of explanation, the direction perpendicular to the thickness direction z of the substrate 11 (hereinafter abbreviated as "thickness direction z") is called the "first direction x1". The direction perpendicular to both the thickness direction z and the first direction x1 is called the "second direction x2". The longitudinal direction of the semiconductor device A10 is the second direction x2.

[0030] As shown in Figure 3, the substrate 11 is an electrically insulating member in which mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and conductive layers (first conductive layer 212, second conductive layer 222, and third conductive layer 232) are arranged. The substrate 11 has three regions: the first substrate 11A, the second substrate 11B, and the third substrate 11C. The first substrate 11A, the second substrate 11B, and the third substrate 11C are arranged spaced apart from each other in the second direction x2. In the second direction x2, the third substrate 11C is located between the first substrate 11A and the second substrate 11B. The substrate 11 may also have other configurations, such as having two regions, the first substrate 11A and the second substrate 11B, or having only one region. As shown in Figure 11, each of the first substrate 11A, the second substrate 11B, and the third substrate 11C has a main surface 111 and a back surface 112 that face opposite each other in the thickness direction z.

[0031] The constituent material of the substrate 11 is a ceramic with excellent thermal conductivity. An example of such a ceramic is aluminum nitride (AlN). The substrate 11 can be a DBC (Direct Bonding Copper) substrate in which copper (Cu) foil is bonded to the main surface 111 and the back surface 112. By using a DBC substrate, mounting layers and conductive layers can be easily formed by patterning the copper foil bonded to the main surface 111. Furthermore, the copper foil bonded to the back surface 112 can serve as a heat transfer layer 62 (details described later).

[0032] As shown in Figures 3 and 8, the main surface 111 of the first substrate 11A has a first mounting layer 211, a first conductive layer 212, a first gate layer 213, a first detection layer 214, and a thermistor mounting layer 215 arranged on it. These are conductive members made of thin metal films such as copper foil. For example, silver (Ag) plating may be applied to their surfaces.

[0033] As shown in Figure 8, the first mounting layer 211 has multiple switching elements 31 and multiple protection elements 32 electrically connected to it. The first mounting layer 211 has a first upper arm mounting layer 211A and a first lower arm mounting layer 211B.

[0034] As shown in Figure 8, the first upper arm mounting layer 211A is located on one end side of the first substrate 11A in the first direction x1 (the upper side in Figure 8). The first upper arm mounting layer 211A is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the first upper arm mounting layer 211A in groups of three each. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the first upper arm mounting layer 211A is not limited to this. In the first upper arm mounting layer 211A, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2. In addition, a first power supply pad 211C is formed at the end of the first upper arm mounting layer 211A that is close to the case 70 in the second direction x2, and is strip-shaped along the first direction x1. The first power supply pad 211C is electrically connected to the first power supply terminal 24A.

[0035] As shown in Figure 8, the first lower arm mounting layer 211B is located between the first upper arm mounting layer 211A and the first conductive layer 212 in the first direction x1. The first lower arm mounting layer 211B is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the first lower arm mounting layer 211B in groups of three each. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the first lower arm mounting layer 211B is not limited to this. In the first lower arm mounting layer 211B, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2. As shown in Figure 15, the first lower arm mounting layer 211B is electrically connected to both the main surface electrodes 311 (details described later) of the multiple switching elements 31 and the anode electrodes 321 (details described later) of the multiple protection elements 32, which are electrically joined to the first upper arm mounting layer 211A via multiple wires 41.

[0036] As shown in Figures 8 and 18, the first conductive layer 212 is electrically connected to the main surface electrodes 311 of multiple switching elements 31 and the anode electrodes 321 of multiple protective elements 32, which are electrically joined to the first lower arm mounting layer 211B via multiple wires 41. The first conductive layer 212 is located on the other end side (lower side in Figure 8) of the first substrate 11A in the first direction x1. The first conductive layer 212 is strip-shaped along the second direction x2. In addition, a second power supply pad 212A, which is strip-shaped along the first direction x1, is formed at the end of the first conductive layer 212 that is close to the case 70 in the second direction x2. The second power supply pad 212A is electrically connected to the second power supply terminal 24B.

[0037] As shown in Figures 15 and 18, the first gate layer 213 is electrically connected to the gate electrodes 313 (details described later) of multiple switching elements 31 that are electrically joined to the first mounting layer 211 via multiple first gate wires 421. The first gate layer 213 is strip-shaped along the second direction x2 and faces the multiple switching elements 31 when viewed from the thickness direction z. The first gate layer 213 has a first upper arm gate layer 213A and a first lower arm gate layer 213B.

[0038] As shown in Figure 8, the first upper arm gate layer 213A is located between the first upper arm mounting layer 211A and the case 70 in the first direction x1. Viewed from the thickness direction z, the first upper arm gate layer 213A faces a plurality of switching elements 31 electrically connected to the first upper arm mounting layer 211A. As shown in Figure 15, the first upper arm gate layer 213A is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 electrically connected to the first upper arm mounting layer 211A via a plurality of first gate wires 421.

[0039] As shown in Figure 8, the first lower arm gate layer 213B is located between the first lower arm mounting layer 211B and the first conductive layer 212 in the first direction x1. Viewed from the thickness direction z, the first lower arm gate layer 213B faces a plurality of switching elements 31 that are electrically connected to the first lower arm mounting layer 211B. As shown in Figure 18, the first lower arm gate layer 213B is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 that are electrically connected to the first lower arm mounting layer 211B via a plurality of first gate wires 421.

[0040] As shown in Figures 15 and 18, the first detection layer 214 is electrically connected to the main surface electrodes 311 of a plurality of switching elements 31 that are electrically joined to the first mounting layer 211 via a plurality of first detection wires 431. The first detection layer 214 is strip-shaped along the second direction x2 and faces the plurality of switching elements 31 when viewed from the thickness direction z. The first detection layer 214 has a first upper arm detection layer 214A and a first lower arm detection layer 214B.

[0041] As shown in Figure 8, the first upper arm detection layer 214A is located between the first upper arm mounting layer 211A and the first upper arm gate layer 213A in the first direction x1. Viewed from the thickness direction z, the first upper arm detection layer 214A faces a plurality of switching elements 31 electrically connected to the first upper arm mounting layer 211A. As shown in Figure 15, the first upper arm detection layer 214A is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 electrically connected to the first upper arm mounting layer 211A via a plurality of first detection wires 431.

[0042] As shown in Figure 8, the first lower arm detection layer 214B is located between the first lower arm mounting layer 211B and the first lower arm gate layer 213B in a first direction x1. The first lower arm detection layer 214B is L-shaped, with a portion extending in the first direction x1 and a portion extending in the second direction x2. Of these, the portion extending in the second direction x2 faces a plurality of switching elements 31 that are electrically connected to the first lower arm mounting layer 211B when viewed from the thickness direction z. As shown in Figure 18, the first lower arm detection layer 214B is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 that are electrically connected to the first lower arm mounting layer 211B via a plurality of first detection wires 431.

[0043] As shown in Figure 8, a thermistor 33 is electrically connected to the thermistor mounting layer 215. The thermistor mounting layer 215 is located near the corner of the first substrate 11A. The thermistor mounting layer 215 is surrounded by the first upper arm mounting layer 211A, the first upper arm gate layer 213A, and the first upper arm detection layer 214A. The thermistor mounting layer 215 has a pair of regions that are spaced apart from each other in the second direction x2. The positive electrode of the thermistor 33 is electrically connected to one region, and the negative electrode of the thermistor 33 is electrically connected to the other region.

[0044] As shown in Figures 3 and 9, the main surface 111 of the second substrate 11B has a second mounting layer 221, a second conductive layer 222, a second gate layer 223, and a second detection layer 224 arranged on it. These are conductive members made of thin metal films such as copper foil. For example, silver plating may be applied to their surfaces.

[0045] As shown in Figure 9, multiple switching elements 31 and multiple protection elements 32 are electrically connected to the second mounting layer 221. The second mounting layer 221 includes a second upper arm mounting layer 221A and a second lower arm mounting layer 221B.

[0046] As shown in Figure 9, the second upper arm mounting layer 221A is located on one end side of the second substrate 11B in the first direction x1 (the upper side in Figure 9). The second upper arm mounting layer 221A is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the second upper arm mounting layer 221A in groups of three each. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the second upper arm mounting layer 221A is not limited to this. In the second upper arm mounting layer 221A, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2.

[0047] As shown in Figure 9, the second lower arm mounting layer 221B is located between the second upper arm mounting layer 221A and the second conductive layer 222 in the first direction x1. The second lower arm mounting layer 221B is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the second lower arm mounting layer 221B in groups of three each. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the second lower arm mounting layer 221B is not limited to this. In the second lower arm mounting layer 221B, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2. As shown in Figure 15, the second lower arm mounting layer 221B is electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and the anode electrodes 321 of the multiple protection elements 32, which are electrically connected to the second upper arm mounting layer 221A, via multiple wires 41. Furthermore, an output pad 221C is formed in a strip shape along the first direction x1 at the end of the second lower arm mounting layer 221B that is close to the case 70 in the second direction x2. The output pad 221C is close to both the second upper arm mounting layer 221A and the second conductive layer 222 in the second direction x2. The output pad 221C is electrically connected to the output terminal 25.

[0048] As shown in Figures 9 and 18, the second conductive layer 222 is electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and the anode electrodes 321 of the multiple protective elements 32, which are electrically joined to the second lower arm mounting layer 221B via multiple wires 41. The second conductive layer 222 is located on the other end side of the second substrate 11B in the first direction x1 (the lower side in Figure 9). The second conductive layer 222 is strip-shaped along the second direction x2.

[0049] As shown in Figures 15 and 18, the second gate layer 223 is electrically connected to the gate electrodes 313 of multiple switching elements 31 that are electrically joined to the second mounting layer 221 via multiple first gate wires 421. The second gate layer 223 is strip-shaped along the second direction x2 and faces the multiple switching elements 31 when viewed from the thickness direction z. The second gate layer 223 has a second upper arm gate layer 223A and a second lower arm gate layer 223B.

[0050] As shown in Figure 9, the second upper arm gate layer 223A is located between the second upper arm mounting layer 221A and the case 70 in the first direction x1. Viewed from the thickness direction z, the second upper arm gate layer 223A faces a plurality of switching elements 31 that are electrically connected to the second upper arm mounting layer 221A. As shown in Figure 15, the second upper arm gate layer 223A is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 that are electrically connected to the second upper arm mounting layer 221A via a plurality of first gate wires 421.

[0051] As shown in Figure 9, the second lower arm gate layer 223B is located between the second lower arm mounting layer 221B and the second conductive layer 222 in the first direction x1. Viewed from the thickness direction z, the second lower arm gate layer 223B faces a plurality of switching elements 31 electrically connected to the second lower arm mounting layer 221B. As shown in Figure 18, the second lower arm gate layer 223B is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 electrically connected to the second lower arm mounting layer 221B via a plurality of first gate wires 421.

[0052] As shown in Figures 15 and 18, the second detection layer 224 is electrically connected to the main surface electrodes 311 of a plurality of switching elements 31 that are electrically joined to the second mounting layer 221 via a plurality of first detection wires 431. The second detection layer 224 is strip-shaped along the second direction x2 and faces the plurality of switching elements 31 when viewed from the thickness direction z. The second detection layer 224 includes a second upper arm detection layer 224A and a second lower arm detection layer 224B.

[0053] As shown in Figure 9, the second upper arm detection layer 224A is located between the second upper arm mounting layer 221A and the second upper arm gate layer 223A in the first direction x1. Viewed from the thickness direction z, the second upper arm detection layer 224A faces a plurality of switching elements 31 electrically connected to the second upper arm mounting layer 221A. As shown in Figure 15, the second upper arm detection layer 224A is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 electrically connected to the second upper arm mounting layer 221A via a plurality of first detection wires 431.

[0054] As shown in Figure 9, the second lower arm detection layer 224B is located between the second lower arm mounting layer 221B and the second lower arm gate layer 223B in the first direction x1. Viewed from the thickness direction z, the second lower arm detection layer 224B faces a plurality of switching elements 31 electrically connected to the second lower arm mounting layer 221B. As shown in Figure 18, the second lower arm detection layer 224B is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 electrically connected to the second lower arm mounting layer 221B via a plurality of first detection wires 431.

[0055] As shown in Figures 3 and 10, the main surface 111 of the third substrate 11C has a third mounting layer 231, a third conductive layer 232, a third gate layer 233, and a third detection layer 234 arranged on it. These are conductive members made of a thin metal film such as copper foil. For example, silver plating may be applied to their surfaces.

[0056] As shown in Figure 10, multiple switching elements 31 and multiple protection elements 32 are electrically connected to the third mounting layer 231. The third mounting layer 231 includes a third upper arm mounting layer 231A and a third lower arm mounting layer 231B.

[0057] As shown in Figure 10, the third upper arm mounting layer 231A is located on one end side of the third substrate 11C in the first direction x1 (the upper side in Figure 10). The third upper arm mounting layer 231A is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the third upper arm mounting layer 231A in pairs. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the third upper arm mounting layer 231A is not limited to this. In the third upper arm mounting layer 231A, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2.

[0058] As shown in Figure 10, the third lower arm mounting layer 231B is located between the third upper arm mounting layer 231A and the third conductive layer 232 in the first direction x1. The third lower arm mounting layer 231B is strip-shaped along the second direction x2. Multiple switching elements 31 and multiple protection elements 32 are electrically connected to the third lower arm mounting layer 231B in pairs. The number of multiple switching elements 31 and multiple protection elements 32 electrically connected to the third lower arm mounting layer 231B is not limited to this. In the third lower arm mounting layer 231B, the multiple switching elements 31 and multiple protection elements 32 are all arranged in the second direction x2. As shown in Figure 15, the third lower arm mounting layer 231B is electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and the anode electrodes 321 of the multiple protection elements 32 via multiple wires 41.

[0059] As shown in Figures 10 and 18, the third conductive layer 232 is electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and the anode electrodes 321 of the multiple protective elements 32, which are electrically joined to the third lower arm mounting layer 231B via multiple wires 41. The third conductive layer 232 is located on the other end side of the third substrate 11C in the first direction x1 (the lower side in Figure 10). The third conductive layer 232 is strip-shaped along the second direction x2.

[0060] As shown in Figures 15 and 18, the third gate layer 233 is electrically connected to the gate electrodes 313 of multiple switching elements 31 that are electrically joined to the third mounting layer 231 via multiple first gate wires 421. The third gate layer 233 is strip-shaped along the second direction x2 and faces the multiple switching elements 31 when viewed from the thickness direction z. The third gate layer 233 has a third upper arm gate layer 233A and a third lower arm gate layer 233B.

[0061] As shown in Figure 10, the third upper arm gate layer 233A is located between the third upper arm mounting layer 231A and the case 70 in the first direction x1. Viewed from the thickness direction z, the third upper arm gate layer 233A faces a plurality of switching elements 31 electrically connected to the third upper arm mounting layer 231A. As shown in Figure 15, the third upper arm gate layer 233A is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 electrically connected to the third upper arm mounting layer 231A via a plurality of first gate wires 421.

[0062] As shown in Figure 10, the third lower arm gate layer 233B is located between the third lower arm mounting layer 231B and the third conductive layer 232 in the first direction x1. The third lower arm gate layer 233B is an L-shaped strip having a portion extending in the first direction x1 and a portion extending in the second direction x2. Of these, the portion extending in the second direction x2 faces a plurality of switching elements 31 that are electrically connected to the third lower arm mounting layer 231B when viewed from the thickness direction z. As shown in Figure 18, the third lower arm gate layer 233B is electrically connected to the gate electrodes 313 of the plurality of switching elements 31 that are electrically connected to the third lower arm mounting layer 231B via a plurality of first gate wires 421.

[0063] As shown in Figures 15 and 18, the third detection layer 234 is electrically connected to the main surface electrodes 311 of a plurality of switching elements 31 that are electrically joined to the third mounting layer 231 via a plurality of first detection wires 431. The third detection layer 234 is strip-shaped along the second direction x2 and faces the plurality of switching elements 31 when viewed from the thickness direction z. The third detection layer 234 includes a third upper arm detection layer 234A and a third lower arm detection layer 234B.

[0064] As shown in Figure 10, the third upper arm detection layer 234A is located between the third upper arm mounting layer 231A and the third upper arm gate layer 233A in the first direction x1. Viewed from the thickness direction z, the third upper arm detection layer 234A faces a plurality of switching elements 31 electrically connected to the third upper arm mounting layer 231A. As shown in Figure 15, the third upper arm detection layer 234A is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 electrically connected to the third upper arm mounting layer 231A via a plurality of first detection wires 431.

[0065] As shown in Figure 10, the third lower arm detection layer 234B is located between the third lower arm mounting layer 231B and the third lower arm gate layer 233B in the first direction x1. Viewed from the thickness direction z, the third lower arm detection layer 234B faces a plurality of switching elements 31 electrically connected to the third lower arm mounting layer 231B. As shown in Figure 18, the third lower arm detection layer 234B is electrically connected to the main surface electrodes 311 of the plurality of switching elements 31 electrically connected to the third lower arm mounting layer 231B via a plurality of first detection wires 431.

[0066] The first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A refer to the respective regions of the "upper arm mounting layer" as described in the claims of the present invention. The first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B refer to the respective regions of the "lower arm mounting layer" as described in the claims of the present invention.

[0067] As shown in Figures 2 and 3, the power terminal 24 is an element of the external connection terminals provided on the semiconductor device A10. As previously mentioned, the power terminal 24 has a first power terminal 24A and a second power terminal 24B. The power terminal 24 is connected to a DC power supply located outside the semiconductor device A10 and is supported by the case 70. The constituent material of the power terminal 24 is, for example, a thin metal plate made of copper. The surface of the thin metal plate may be plated with nickel (Ni). The first power terminal 24A is the positive terminal (P terminal) of the semiconductor device A10. The second power terminal 24B is the negative terminal (N terminal) of the semiconductor device A10. The first power terminal 24A and the second power terminal 24B are spaced apart from each other in the first direction x1. The first power terminal 24A and the second power terminal 24B are both the same shape.

[0068] As shown in Figure 11, the power terminal 24 is bent in a hook shape when viewed from a first direction x1. In the power terminal 24, a connection hole 241 is provided in the portion that is exposed to the outside of the semiconductor device A10 and perpendicular to the thickness direction z, and penetrates in the thickness direction z. A fastening member such as a bolt is inserted into the connection hole 241. As shown in Figure 8, in the power terminal 24, a conductive connection member 242 is connected to the portion that is located inside the case 70 and perpendicular to the thickness direction z. The connection member 242 is, for example, a plurality of wires made of aluminum (Al) as a constituent material. The other end of the connection member 242 connected to the first power terminal 24A is connected to the first power pad 211C of the first upper arm mounting layer 211A. As a result, the first power terminal 24A is electrically connected to the first upper arm mounting layer 211A via the connection member 242. In addition, the other end of the connection member 242 connected to the second power terminal 24B is connected to the second power pad 212A of the first conductive layer 212. As a result, the second power terminal 24B is electrically connected to the first conductive layer 212 via the connecting member 242.

[0069] As shown in Figures 2 and 3, the output terminal 25 is an element of the external connection terminals provided on the semiconductor device A10. The output terminal 25 is divided into two parts: a first output terminal 25A and a second output terminal 25B. Alternatively, the output terminal 25 may be a single, undivided terminal. The output terminal 25 is connected to a drive target, such as a motor, located outside the semiconductor device A10, and is supported by the case 70. In the second direction x2, the output terminal 25 is located on the opposite side of the substrate 11 from the power terminal 24. The material of the output terminal 25 is the same thin metal plate as the power terminal 24. The surface of the thin metal plate may be nickel-plated. Furthermore, the first output terminal 25A and the second output terminal 25B are connected in parallel to the second lower arm mounting layer 221B. The first output terminal 25A and the second output terminal 25B are each connected to a drive target of the semiconductor device A10 located outside. In the second direction x2, the first output terminal 25A faces the first power terminal 24A, and the second output terminal 25B faces the second power terminal 24B. The first output terminal 25A and the second output terminal 25B are spaced apart from each other in the first direction x1. The first output terminal 25A and the second output terminal 25B are both identical in shape.

[0070] As shown in Figure 11, the output terminal 25 is bent in a hook shape when viewed from a first direction x1. In the output terminal 25, a connecting hole 251 is provided in the portion that is exposed to the outside of the semiconductor device A10 and perpendicular to the thickness direction z, and penetrates in the thickness direction z. A fastening member such as a bolt is inserted into the connecting hole 251. As shown in Figure 9, in the output terminal 25, a conductive connecting member 252 is connected to the portion that is located inside the case 70 and perpendicular to the thickness direction z. The connecting member 252 is, for example, a plurality of wires made of aluminum. The other end of the connecting member 252 connected to the output terminal 25 is connected to the output pad 221C of the second lower arm mounting layer 221B located on the second substrate 11B. As a result, the output terminal 25 is electrically connected to the second lower arm mounting layer 221B via the connecting member 252.

[0071] As shown in Figure 10, the relay conductive member 261 connects the first mounting layer 211 and the third mounting layer 231, and also connects the second mounting layer 221 and the third mounting layer 231. As a result, the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 are electrically connected to each other via the relay conductive member 261. In addition, as shown in Figure 10, the relay conductive member 261 connects the first conductive layer 212 and the third conductive layer 232, and also connects the second conductive layer 222 and the third conductive layer 232. As a result, the first conductive layer 212, the second conductive layer 222, and the third conductive layer 232 are electrically connected to each other via the relay conductive member 261. The relay conductive member 261 is, for example, a plurality of wires made of aluminum as its constituent material.

[0072] As shown in Figure 10, the relay conductive member 261 includes a first member 261A, a second member 261B, and a third member 261C. The first member 261A, the second member 261B, and the third member 261C all extend in the second direction x2. The first member 261A connects the first upper arm mounting layer 211A and the third upper arm mounting layer 231A, and also connects the second upper arm mounting layer 221A and the third upper arm mounting layer 231A. As a result, the first upper arm mounting layer 211A and the second upper arm mounting layer 221A are electrically connected to each other via the first member 261A. The second member 261B connects the first lower arm mounting layer 211B and the third lower arm mounting layer 231B, and also connects the second lower arm mounting layer 221B and the third lower arm mounting layer 231B. As a result, the first lower arm mounting layer 211B and the second lower arm mounting layer 221B are electrically connected to each other via the second member 261B. The third member 261C connects the first conductive layer 212 and the third conductive layer 232, and also connects the second conductive layer 222 and the third conductive layer 232. As a result, the first conductive layer 212 and the second conductive layer 222 are electrically connected to each other via the third member 261C.

[0073] As shown in Figure 10, the multiple first conductive members 262 connect the first gate layer 213 and the third gate layer 233, and also connect the second gate layer 223 and the third gate layer 233. As a result, the first gate layer 213, the second gate layer 223, and the third gate layer 233 are electrically connected to each other via the multiple first conductive members 262. The multiple first conductive members 262 are, for example, wires made of aluminum. All of the multiple first conductive members 262 extend in the second direction x2. The multiple first conductive members 262 consist of four wires. The first first conductive member 262 connects the first upper arm gate layer 213A and the third upper arm gate layer 233A. The second first conductive member 262 connects the second upper arm gate layer 223A and the third upper arm gate layer 233A. The third first conductive member 262 connects the first lower arm gate layer 213B and the third lower arm gate layer 233B. The fourth first conductive member 262 connects the second lower arm gate layer 223B and the third lower arm gate layer 233B.

[0074] As shown in Figure 10, the multiple second conductive members 263 connect the first detection layer 214 and the third detection layer 234, and also connect the second detection layer 224 and the third detection layer 234. As a result, the first detection layer 214, the second detection layer 224, and the third detection layer 234 are electrically connected to each other via the multiple second conductive members 263. The multiple second conductive members 263 are, for example, wires made of aluminum. All of the multiple second conductive members 263 extend in the second direction x2. The multiple second conductive members 263 consist of four wires. The first second conductive member 263 connects the first upper arm detection layer 214A and the third upper arm detection layer 234A. The second second conductive member 263 connects the second upper arm detection layer 224A and the third upper arm detection layer 234A. The third second conductive member 263 connects the first lower arm detection layer 214B and the third lower arm detection layer 234B. The fourth second conductive member 263 connects the second lower arm detection layer 224B and the third lower arm detection layer 234B.

[0075] As shown in Figures 2 to 4, the gate terminal 27 is an element of the external connection terminals provided on the semiconductor device A10. The gate terminal 27 is connected to a drive circuit (e.g., a gate driver) of the semiconductor device A10 located outside. The gate terminal 27 is positioned facing the substrate 11 when viewed from the thickness direction z and is supported by the case 70. The gate terminal 27 protrudes toward the side (thickness direction z) facing the main surface 111 of the substrate 11 in the thickness direction z. The gate terminal 27 is a metal rod made of, for example, copper. The surface of the metal rod is plated with tin (Sn). Nickel plating may be applied between the surface of the metal rod and the tin plating. As shown in Figure 12, the tip of the gate terminal 27 that is close to the substrate 11 in the thickness direction z is bent in a hook shape along the first direction x1. The gate terminal 27 includes a first gate terminal 27A and a second gate terminal 27B. A pair of second gate wires 422 are connected to the first gate terminal 27A and the second gate terminal 27B. The material of the pair of second gate wires 422 is, for example, aluminum.

[0076] As shown in Figure 10, the first gate terminal 27A is positioned opposite the second substrate 11B so as to be close to the second upper arm gate layer 223A when viewed from the thickness direction z. The other end of the second gate wire 422, one end of which is connected to the first gate terminal 27A, is connected to the third upper arm gate layer 233A. As a result, the first gate terminal 27A is electrically connected to the gate electrodes 313 of the multiple switching elements 31 that are electrically joined to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A.

[0077] As shown in Figure 10, the second gate terminal 27B is positioned opposite the third substrate 11C so as to be close to the third lower arm gate layer 233B when viewed from the thickness direction z. The other end of the second gate wire 422, one end of which is connected to the second gate terminal 27B, is connected to the third lower arm gate layer 233B. As a result, the second gate terminal 27B is electrically connected to the gate electrodes 313 of a plurality of switching elements 31 that are electrically joined to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B.

[0078] As shown in Figures 2 to 4, the element current detection terminal 281 is an element of the external connection terminals provided on the semiconductor device A10. The element current detection terminal 281 is connected to the control circuit of the semiconductor device A10 located externally. The element current detection terminal 281 is positioned facing the substrate 11 and is supported by the case 70. The element current detection terminal 281 protrudes in the thickness direction z toward the side where the gate terminal 27 protrudes. The element current detection terminal 281 is made of a metal rod based on the same constituent material as the gate terminal 27. The shape of the element current detection terminal 281 is the same as the shape of the gate terminal 27. Therefore, the tip of the element current detection terminal 281 that is close to the substrate 11 in the thickness direction z is bent in a hook shape along the first direction x1. The element current detection terminal 281 includes a first detection terminal 281A and a second detection terminal 281B. A pair of second detection wires 432 are connected to the first detection terminal 281A and the second detection terminal 281B. The constituent material of the pair of second detection wires 432 is, for example, aluminum.

[0079] As shown in Figure 10, the first detection terminal 281A is positioned opposite the second substrate 11B so as to be close to the second upper arm detection layer 224A when viewed from the thickness direction z, and is also close to the first gate terminal 27A. The other end of the second detection wire 432, one end of which is connected to the first detection terminal 281A, is connected to the second upper arm detection layer 224A. As a result, the first detection terminal 281A is electrically connected to the main surface electrodes 311 of a plurality of switching elements 31 that are electrically joined to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A.

[0080] As shown in Figure 10, the second detection terminal 281B is positioned opposite the first substrate 11A so as to be close to the first lower arm detection layer 214B when viewed from the thickness direction z, and is also close to the second gate terminal 27B. The other end of the second detection wire 432, one end of which is connected to the second detection terminal 281B, is connected to the first lower arm detection layer 214B. As a result, the second detection terminal 281B is electrically connected to the main surface electrodes 311 of a plurality of switching elements 31 that are electrically joined to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B.

[0081] The power supply current detection terminal 282 is an element of the external connection terminals provided on the semiconductor device A10, as shown in Figures 2 to 4 and Figure 9. The power supply current detection terminal 282 is connected to the control circuit of the semiconductor device A10 located externally and is supported by the case 70. The power supply current detection terminal 282 protrudes in the thickness direction z toward the side where the gate terminal 27 protrudes. The power supply current detection terminal 282 is made of a metal rod made of the same constituent material as the gate terminal 27. The position of the power supply current detection terminal 282 in the first direction x1 is the same as that of the first gate terminal 27A and the first detection terminal 281A, and in the second direction x2 it is located spaced apart from the first detection terminal 281A toward the first output terminal 25A. The power supply current detection terminal 282 is positioned opposite the second substrate 11B so as to be close to the second upper arm mounting layer 221A in the first direction x1. The shape of the power supply current detection terminal 282 is the same as that of the gate terminal 27. Therefore, the tip of the power supply current detection terminal 282, which is close to the second substrate 11B in the thickness direction z, is bent in a hook shape along the first direction x1. One end of the power supply current detection wire 44 is connected to this tip. The other end of the power supply current detection wire 44 is connected to the second upper arm mounting layer 221A. As a result, the power supply current detection terminal 282 is electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A. The material of the power supply current detection wire 44 is, for example, aluminum.

[0082] The pair of thermistor terminals 29 are an element of the external connection terminals provided on the semiconductor device A10, as shown in Figures 2 to 4 and Figure 8. The pair of thermistor terminals 29 are connected to the control circuit of the semiconductor device A10 located externally and are supported by the case 70. The pair of thermistor terminals 29 protrude in the thickness direction z toward the side where the gate terminal 27 protrudes. The pair of thermistor terminals 29 are made of metal rods based on the same constituent material as the gate terminal 27. The position of the pair of thermistor terminals 29 in the first direction x1 is the same as that of the first gate terminal 27A and the first detection terminal 281A, and in the second direction x2 they are spaced apart from the first gate terminal 27A toward the first power terminal 24A. The pair of thermistor terminals 29 are positioned opposite the first substrate 11A so as to be close to the thermistor mounting layer 215 in the first direction x1. The shape of the pair of thermistor terminals 29 is the same as that of the gate terminal 27. Therefore, the tips of the pair of thermistor terminals 29 that are close to the first substrate 11A in the thickness direction z are bent in a hook shape along the first direction x1. One end of a pair of thermistor wires 45 is connected to the tip of each of the pair of thermistor terminals 29. The other ends of the pair of thermistor wires 45 are connected to a pair of regions of the thermistor mounting layer 215. As a result, the thermistor terminals 29 are electrically connected to the thermistor 33. The constituent material of the pair of thermistor wires 45 is, for example, aluminum.

[0083] As shown in Figure 3, the multiple switching elements 31 are semiconductor elements arranged in the second direction x2 and electrically joined on the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, respectively. The multiple switching elements 31 are rectangular (square in semiconductor device A10) when viewed from the thickness direction z. The switching elements 31 are MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) made using a semiconductor material mainly composed of silicon carbide (SiC). Note that the switching elements 31 are not limited to MOSFETs but may also be IGBTs (Insulated Gate Bipolar Transistors). In the description of semiconductor device A10, the switching elements 31 are of the n-channel type and are MOSFETs made using a semiconductor material mainly composed of silicon carbide. In semiconductor device A10, the thickness of the switching elements 31 is 400 μm or less, more preferably 150 μm or less. The breakdown voltage of the switching elements 31 is 1,200 V or more.

[0084] As shown in Figures 15 to 20, each of the multiple switching elements 31 has a main surface 31A, a back surface 31B, a side surface 31C, a main surface electrode 311, a back surface electrode 312, a gate electrode 313, and an insulating film 314. The main surface 31A, back surface 31B, and side surface 31C refer to the "first element main surface," "first element back surface," and "first element side surface" as described in the claims of the present invention. The main surface 31A faces the side of the substrate 11 facing the main surface 111 in the thickness direction z. The back surface 31B faces the side opposite to the main surface 31A. The multiple switching elements 31 are electrically joined to the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, respectively, with the back surface 31B facing the main surface 111. The side surface 31C is connected to both the main surface 31A and the back surface 31B. The side surface 31C has multiple regions (four regions in the case of semiconductor device A10) each facing either the first direction x1 or the second direction x2.

[0085] As shown in Figures 15 to 20, the main surface electrode 311 is provided on the main surface 31A. Source current flows through the main surface electrode 311. The main surface electrode 311 has a pair of first pad portions 311A ​​and a pair of second pad portions 311B. Both the pair of first pad portions 311A ​​and the pair of second pad portions 311B are regions of the main surface electrode 311 that are spaced apart from each other in the second direction x2. In a plurality of switching elements 31 electrically connected to the first mounting layer 211, the pair of second pad portions 311B are located in the first direction x1 on the opposite side of the pair of first pad portions 311A ​​from either the first lower arm mounting layer 211B or the first conductive layer 212. The positional relationship between the pair of second pad portions 311B and the pair of first pad portions 311A ​​is the same for a plurality of switching elements 31 electrically connected to the second mounting layer 221 and the third mounting layer 231, respectively.

[0086] As shown in Figure 15, in the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A, one end of multiple first detection wires 431 is connected to one of the multiple second pad portions 311B. The other end of the multiple first detection wires 431 is connected to one of the first upper arm detection layer 214A, the second upper arm detection layer 224A, and the third upper arm detection layer 234A. Also, as shown in Figure 18, in the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, one end of multiple first detection wires 431 is connected to one of the multiple first pad portions 311A. The other ends of the plurality of first detection wires 431 are connected to one of the first lower arm detection layer 214B, the second lower arm detection layer 224B, and the third lower arm detection layer 234B. Each of the plurality of main surface electrodes 311 is electrically connected to one of the first detection layer 214, the second detection layer 224, and the third detection layer 234 by the plurality of first detection wires 431. The constituent material of the plurality of first detection wires 431 is, for example, gold (Au).

[0087] As shown in Figures 16 to 20 (excluding Figure 18), the back electrode 312 is provided across the entire back surface 31B. A drain current flows through the back electrode 312. The back electrode 312 is electrically connected to one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 by a first bonding layer 391. The first bonding layer 391 is conductive. The first bonding layer 391 is sandwiched between the multiple back electrodes 312 and the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231. The constituent material of the first bonding layer 391 is, for example, lead-free solder mainly composed of tin. Through the first bonding layer 391, each of the multiple back electrodes 312 is electrically connected to one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231.

[0088] As shown in Figures 15 and 18, the gate electrode 313 is provided on the main surface 31A. A gate voltage is applied to the gate electrode 313 to drive each of the multiple switching elements 31. As shown in Figure 15, in the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A, the gate electrode 313 is close to a pair of second pad portions 311B of the main surface electrode 311. The other ends of a plurality of first gate wires 421, one end of which is connected to one of the first upper arm gate layer 213A, the second upper arm gate layer 223A, and the third upper arm gate layer 233A, are connected to the plurality of gate electrode 313. Furthermore, as shown in Figure 18, in the plurality of switching elements 31 electrically connected to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, the gate electrodes 313 are close to a pair of first pad portions 311A ​​of the main surface electrode 311. The other ends of a plurality of first gate wires 421, one end of which is connected to one of the first lower arm gate layer 213B, the second lower arm gate layer 223B, and the third lower arm gate layer 233B, are connected to the plurality of gate electrodes 313. Each of the plurality of gate electrodes 313 is electrically connected to one of the first gate layer 213, the second gate layer 223, and the third gate layer 233 by the plurality of first gate wires 421. The constituent material of the plurality of first gate wires 421 is, for example, gold.

[0089] As shown in Figures 15 to 20, the insulating film 314 is provided on the main surface 31A. The insulating film 314 has electrical insulating properties. The insulating film 314 surrounds the main surface electrode 311 when viewed from the thickness direction z. The insulating film 314 is made up of, for example, silicon dioxide (SiO2) layers, silicon nitride (Si3N4) layers, and polybenzoxazole (PBO) layers stacked in this order from the main surface 31A. In addition, a polyimide layer may be used instead of the polybenzoxazole layer in the insulating film 314. In Figures 15 to 20, the length from the periphery 314A of the insulating film 314 to the main surface electrode 311 when viewed from the thickness direction z is shown as the gap Gp of the multiple switching elements 31. The gap Gp is ​​the length along either the first direction x1 or the second direction x2. The periphery 314A is rectangular (square in semiconductor device A10) when viewed from the thickness direction z. When viewed from the thickness direction z, the ratio of the length of the gap Gp to the length of one side of the peripheral edge 314A (or the length of the shorter side if the peripheral edge 314A is rectangular) is set to 5-25%. The larger the length of the gap Gp, the better the dielectric strength of the switching element 31.

[0090] As shown in Figure 3, the multiple protection elements 32 are semiconductor elements arranged in the second direction x2 and electrically joined on each of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231. The multiple protection elements 32 are rectangular in shape when viewed from the thickness direction z. The multiple protection elements 32 are arranged to be electrically connected to the multiple switching elements 31 individually. The multiple protection elements 32 are electrically connected to both the main surface electrode 311 and the back surface electrode 312 of the multiple switching elements 31. As a result, one switching element 31 and one corresponding protection element 32 constitute a pair of parallel circuits. The multiple protection elements 32 are Schottky barrier diodes made of a semiconductor material mainly composed of silicon carbide. In the semiconductor device A10, the thickness of the protection elements 32 is 400 μm or less, more preferably 150 μm or less. The breakdown voltage of the protection elements 32 is 1,200 V or more.

[0091] As shown in Figures 15 to 20, each of the multiple protective elements 32 has a main surface 32A, a back surface 32B, a side surface 32C, an anode electrode 321, a cathode electrode 322, and an insulating film 323. The main surface 32A refers to the "second element main surface" as described in the claims of the present invention. The main surface 32A faces the side of the substrate 111 facing the main surface 111 in the thickness direction z. The back surface 32B faces the opposite side from the main surface 32A. The multiple protective elements 32 are electrically joined to the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, respectively, with the back surface 32B facing the main surface 111. The side surface 32C is connected to both the main surface 32A and the back surface 32B. The side surface 32C has multiple regions (four regions in semiconductor device A10) each facing either the first direction x1 or the second direction x2.

[0092] As shown in Figures 15 to 20, the anode electrode 321 is provided on the main surface 32A. The anode electrode 321 is electrically connected to the main surface electrode 311 of the switching element 31 to which the protective element 32 on which it is provided corresponds.

[0093] As shown in Figures 16 and 19, the cathode electrode 322 is provided across the entire back surface 32B. The cathode electrode 322 is electrically bonded to one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 by a second bonding layer 392. The second bonding layer 392 is conductive. The second bonding layer 392 is sandwiched between the multiple cathode electrodes 322 and the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231. The constituent material of the second bonding layer 392 is the same as the constituent material of the first bonding layer 391. The second bonding layer 392 provides electrical conductivity between the cathode electrode 322 and the back surface electrode 312 of the switching element 31 corresponding to the protective element 32 on which the cathode electrode 322 is provided, via one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231.

[0094] As shown in Figures 16 and 19, the insulating film 323 is provided on the main surface 32A. The insulating film 323 has electrical insulating properties. As shown in Figures 15 and 18, the insulating film 323 surrounds the anode electrode 321 when viewed from the thickness direction z. The insulating film 323 is made up of, for example, a silicon dioxide layer, a silicon nitride layer, and a polybenzoxazole layer stacked in this order from the main surface 32A. In addition, a polyimide layer may be used instead of the polybenzoxazole layer in the insulating film 323.

[0095] The thermistor 33 is an element electrically joined to the thermistor mounting layer 215, as shown in Figures 3 and 8. Thermistor 33 is, for example, an NTC (Negative Temperature Coefficient) thermistor. An NTC thermistor has the characteristic of its resistance decreasing gradually with increasing temperature. Thermistor 33 is used as a temperature detection sensor for semiconductor device A10.

[0096] As shown in Figures 15 to 17, the multiple wires 41 are connected to the main surface electrodes 311 of the multiple switching elements 31 and to one of the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B. As shown in Figures 18 to 20, the multiple wires 41 are connected to the main surface electrodes 311 of the multiple switching elements 31 and to one of the first conductive layer 212, the second conductive layer 222, and the third conductive layer 232. The constituent material of the multiple wires 41 is, for example, aluminum. The diameter of the wires 41 is larger than the diameter of the first gate wire 421 and the first detection wire 431, respectively.

[0097] As shown in Figures 15 to 17, in the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the first lower arm mounting layer 211B. As shown in Figures 18 to 20, in the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the first conductive layer 212. As a result, the main surface electrodes 311 of the multiple switching elements 31 electrically connected to the first mounting layer 211 are conductive to either the first lower arm mounting layer 211B or the first conductive layer 212.

[0098] As shown in Figures 15 to 17, in the multiple switching elements 31 electrically connected to the second upper arm mounting layer 221A, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the second lower arm mounting layer 221B. As shown in Figures 18 to 20, in the multiple switching elements 31 electrically connected to the second lower arm mounting layer 221B, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the second conductive layer 222. As a result, the main surface electrodes 311 of the switching elements 31 electrically connected to the second mounting layer 221 are conductive to either the second lower arm mounting layer 221B or the second conductive layer 222.

[0099] As shown in Figures 15 to 17, in the multiple switching elements 31 electrically connected to the third upper arm mounting layer 231A, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the third lower arm mounting layer 231B. As shown in Figures 18 to 20, in the multiple switching elements 31 electrically connected to the third lower arm mounting layer 231B, the multiple wires 41 are connected to the multiple main surface electrodes 311 and the third conductive layer 232. As a result, the main surface electrodes 311 of the switching elements 31 electrically connected to the third mounting layer 231 are conductive to either the third lower arm mounting layer 231B or the third conductive layer 232.

[0100] As shown in Figures 15 to 20, the plurality of wires 41 extend in a first direction x1. Each of the plurality of wires 41 has a first bonding portion 411. The plurality of first bonding portions 411 are in contact with the main surface electrodes 311 of the plurality of switching elements 31. In each of the plurality of switching elements 31, the plurality of wires 41 include a pair of inner wires 41A and a pair of outer wires 41B. The pair of outer wires 41B are arranged on both sides of the pair of inner wires 41A in a second direction x2.

[0101] Based on Figures 15 to 17, the configuration of multiple wires 41 in each of the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A will be described. As shown in Figure 17, the first bonding portion 411 of a pair of inner wires 41A is in contact with a pair of first pad portions 311A ​​of the main surface electrode 311. As shown in Figure 16, the first bonding portion 411 of a pair of outer wires 41B is in contact with both a pair of first pad portions 311A ​​and a pair of second pad portions 311B of the main surface electrode 311. As shown in Figures 15 and 16, each of the first bonding portions 411 of a pair of outer wires 41B has a first connection portion 411A, a second connection portion 411B, and a connecting portion 411C. The first connection portion 411A is in contact with the first pad portion 311A. The second connection portion 411B is in contact with the second pad portion 311B. The connecting portion 411C is sandwiched between the first connection portion 411A and the second connection portion 411B in the first direction x1. The connecting portion 411C protrudes in the thickness direction z toward the side facing the main surface 31A of the switching element 31.

[0102] As shown in Figures 15 and 16, each of the multiple wires 41 in each of the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A, each has a second bonding portion 412. The second bonding portion 412 is in contact with the anode electrode 321 of the protection element 32. As a result, the anode electrodes 321 of the multiple protection elements 32 electrically connected to the first upper arm mounting layer 211A are electrically connected to both the main surface electrodes 311 of the corresponding multiple switching elements 31 and the first lower arm mounting layer 211B. The anode electrodes 321 of the protection elements 32 electrically connected to the second upper arm mounting layer 221A are electrically connected to both the main surface electrodes 311 of the corresponding switching elements 31 and the second lower arm mounting layer 221B. Furthermore, the anode electrode 321 of the protective element 32, which is electrically connected to the third upper arm mounting layer 231A, is electrically connected to both the main surface electrode 311 of the corresponding switching element 31 and the third lower arm mounting layer 231B.

[0103] Based on Figures 18 to 20, the configuration of multiple wires 41 in each of the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B will be described. As shown in Figure 20, the first bonding portion 411 of a pair of inner wires 41A is in contact with a pair of first pad portions 311A ​​of the main surface electrode 311. As shown in Figure 19, the first bonding portion 411 of a pair of outer wires 41B is in contact with both a pair of first pad portions 311A ​​and a pair of second pad portions 311B of the main surface electrode 311. As shown in Figures 18 and 19, each of the first bonding portions 411 of a pair of outer wires 41B has a first connection portion 411A, a second connection portion 411B, and a connecting portion 411C. The first connection portion 411A is in contact with the first pad portion 311A. The second connection portion 411B is in contact with the second pad portion 311B. The connecting portion 411C is sandwiched between the first connection portion 411A and the second connection portion 411B in the first direction x1. The connecting portion 411C protrudes in the thickness direction z toward the side facing the main surface 31A of the switching element 31.

[0104] As shown in Figures 18 and 19, each pair of outer wires 41B in each of the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, each have a second bonding portion 412. The second bonding portion 412 is in contact with the anode electrode 321 of the protective element 32. As a result, the anode electrodes 321 of the multiple protective elements 32 electrically connected to the first lower arm mounting layer 211B are electrically connected to both the main surface electrodes 311 of the corresponding multiple switching elements 31 and the first conductive layer 212. The anode electrodes 321 of the protective elements 32 electrically connected to the second lower arm mounting layer 221B are electrically connected to both the main surface electrodes 311 of the corresponding switching elements 31 and the second conductive layer 222. Furthermore, the anode electrode 321 of the protective element 32, which is electrically connected to the third lower arm mounting layer 231B, is electrically connected to both the main surface electrode 311 of the corresponding switching element 31 and the third conductive layer 232.

[0105] As shown in Figure 18, a pair of auxiliary wires 46 are connected to each of the anode electrodes 321 of a plurality of protective elements 32 that are electrically joined to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, respectively. The other ends of the pair of auxiliary wires 46 are connected to a pair of second pad portions 311B of the main surface electrodes 311 of a plurality of switching elements 31 corresponding to the plurality of protective elements 32. The pair of auxiliary wires 46 are located between a pair of outer wires 41B in the second direction x2. The constituent material of the pair of auxiliary wires 46 is the same as the constituent material of the plurality of wires 41. Also, the diameter of the auxiliary wires 46 is the same as the diameter of the wires 41.

[0106] As shown in Figures 15 to 20, the moisture-resistant layer 51 covers the sides 31C of at least one of the multiple switching elements 31. The constituent material of the moisture-resistant layer 51 is selected to be an electrical insulating material that is resistant to temperature cycling and has lower moisture permeability than the sealing resin 52 (silicone gel in semiconductor device A10). The moisture-resistant layer 51, in which such an electrical insulating material is selected, is composed of polyimide and silicone gel. The weight content ratio of polyimide and silicone gel in the moisture-resistant layer 51 is 1 part silicone gel to 1.5 to 7.0 parts polyimide. In other words, in the moisture-resistant layer 51, the weight of polyimide is greater than the weight of silicone gel. In the moisture-resistant layer 51, polyimide molecules and silicone gel molecules are mixed together. More preferably, polyimide molecules and silicone gel molecules are uniformly dispersed throughout the moisture-resistant layer 51. This effectively suppresses the occurrence of cracks in the moisture-resistant layer 51 due to temperature cycling, and thus appropriately maintains the function of the moisture-resistant layer 51 in suppressing moisture intrusion. In semiconductor device A10, an example of a moisture-resistant layer 51 composed only of polyimide and silicone gel is described, but this does not preclude the use of other materials in addition to these to constitute the moisture-resistant layer 51. Furthermore, in semiconductor device A10, an example of a moisture-resistant layer 51 composed of a mixed material of polyimide and silicone gel is described, but other materials with low moisture permeability may be selected. For example, the moisture-resistant layer 51 may be composed of a mixed material of polybenzoxazole and silicone gel.

[0107] An example of a method for forming a moisture-resistant layer 51 of a semiconductor device A10 is described below. A synthetic resin material containing polyimide, silicone gel, and a solvent, and having fluidity, is prepared. The solvent is volatile. Next, the synthetic resin material is dropped onto the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) using a dispenser. As a result, the synthetic resin material wets and spreads over the side surface 31C of the switching element 31, so that the side surface 31C is covered with the synthetic resin material. Finally, the moisture-resistant layer 51 is formed by thermal curing the synthetic resin material. At this time, the solvent evaporates. With this formation method, it is easy to construct a moisture-resistant layer 51 that covers the side surface 31C of the switching element 31.

[0108] As shown in Figures 15 to 17, the moisture-resistant layer 51 is in contact with both one of the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A, and the side surface 31C of at least one of the multiple switching elements 31. In the thickness direction z, the moisture-resistant layer 51 spans between one of the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A and the side surface 31C, i.e., the bonding layer 39 and the back surface electrode 312.

[0109] As shown in Figures 18 to 20, the moisture-resistant layer 51 is in contact with both the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, and the side surface 31C of at least one of the multiple switching elements 31. In the thickness direction z, the moisture-resistant layer 51 spans between the side surface 31C and the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, i.e., the bonding layer 39 and the back surface electrode 312.

[0110] Therefore, the moisture-resistant layer 51 is in contact with both the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, and with at least one of the multiple side surfaces 31C. The moisture-resistant layer 51 spans between the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 and the side surfaces 31C in the thickness direction z.

[0111] As shown in Figures 15, 16, 18, and 19, the moisture-resistant layer 51 integrally covers the side surface 31C of the switching element 31 and the side surface 32C of the protective element 32 (a protective element 32 connected in antiparallel to the switching element 31) that is paired with the switching element 31. In the examples shown in these figures, the moisture-resistant layer 51 is provided corresponding to a pair of switching elements 31 and protective elements 32. That is, the moisture-resistant layer 51 is divided into multiple regions, and these multiple regions are configured to cover the side surface 31C of the pair of switching elements 31 and the side surface 32C of the protective element 32. In addition to this configuration, in each of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, the moisture-resistant layer 51 may integrally cover the side surfaces 31C of multiple switching elements 31.

[0112] The sealing resin 52 is housed in an area surrounded by the case 70 and the heat sink 61, as shown in Figures 11 and 12. As shown in Figures 16, 17, 19, and 20, the sealing resin 52 covers both the multiple switching elements 31 and the moisture-resistant layer 51. In addition to these, the sealing resin 52 also covers the multiple protective elements 32. The sealing resin 52 is preferably a synthetic resin that has excellent heat resistance and adhesion, as well as electrical insulation properties. The sealing resin 52 is, for example, a silicone gel mainly composed of thermosetting organopolysiloxane. The sealing resin 52 is exposed to the atmosphere.

[0113] As shown in Figures 11 and 12, the heat sink 61 is bonded to the back surface 112 of the substrate 11. In the semiconductor device A10, the heat sink 61 is bonded to the back surface 112 of the first substrate 11A, the back surface 112 of the second substrate 11B, and the back surface 112 of the third substrate 11C via a heat transfer layer 62 and a substrate bonding layer 69 (both of which will be described in detail later). The heat sink 61 is made of a metal plate, for example, made of copper. The surface of the metal plate may be nickel plated. As shown in Figures 7 to 9, a plurality of support holes 611 are provided at the four corners of the heat sink 61 when viewed from the thickness direction z. Each of the plurality of support holes 611 penetrates the heat sink 61 in the thickness direction z. The plurality of support holes 611 are used to support the heat sink 61, which is bonded to the substrate 11, in the case 70.

[0114] As shown in Figures 11 and 12, the heat transfer layer 62 is located on the back surface 112 of the substrate 11. The heat transfer layer 62 is made of a metallic material such as copper foil. The heat transfer layer 62 conducts the heat generated by the operation of the multiple switching elements 31 to the heat sink 61.

[0115] As shown in Figures 11 and 12, the substrate bonding layer 69 is a bonding material interposed between the heat sink 61 and the heat transfer layer 62. In semiconductor device A10, the constituent material of the substrate bonding layer 69 is lead-free solder mainly composed of tin. The heat sink 61 is bonded to the substrate 11 by the substrate bonding layer 69.

[0116] As shown in Figure 3, the case 70 is an electrical insulating member that surrounds the substrate 11 when viewed from the thickness direction z. The case 70 is frame-shaped. The case 70 is made of a synthetic resin that has electrical insulating properties and excellent heat resistance, such as PPS (polyphenylene sulfide). The case 70 has a pair of side walls 71, a pair of terminal bases 72, a plurality of mounting parts 73, a power terminal block 74, and an output terminal block 75.

[0117] As shown in Figures 2, 3, 5, and 6, the pair of side walls 71 are spaced apart from each other in the first direction x1 and have a groove shape. Each side wall 71 is positioned along both the second direction x2 and the thickness direction z, and one end in the thickness direction z is in contact with the heat sink 61. Both ends of each side wall 71 in the second direction x2 are connected to a pair of terminal bases 72. Inside one side wall 71 are the first gate terminal 27A, the first detection terminal 281A, the power supply current detection terminal 282, and a pair of thermistor terminals 29. Inside the other side wall 71 are the second gate terminal 27B and the second detection terminal 281B. As shown in Figures 8 to 10, the tips of these terminals that are close to the substrate 11 in the thickness direction z are all supported by the side walls 71.

[0118] As shown in Figures 3, 8, and 9, a pair of terminal bases 72 are spaced apart from each other in a second direction x2. Each terminal base 72 is positioned along the second direction x2. One terminal base 72 is connected to a power terminal block 74 that protrudes outward in the second direction x2, and a portion of the power terminals 24 are supported by this terminal base 72. The other terminal base 72 is connected to an output terminal block 75 that protrudes outward in the second direction x2, and a portion of the output terminals 25 are supported by this terminal base 72.

[0119] As shown in Figures 2, 8, and 9, the multiple mounting portions 73 are provided at the four corners of the case 70 when viewed from the thickness direction z. Each of the multiple mounting portions 73 is provided with a mounting hole 731 that penetrates the mounting portion 73 in the thickness direction z. The positions of the multiple mounting holes 731 correspond to the multiple support holes 611 provided in the heat sink 61. The heat sink 61 is supported by the case 70 by fitting fastening members such as pins into the multiple mounting holes 731 and the multiple support holes 611.

[0120] As shown in Figures 2, 5, and 8, the power terminal block 74 supports the power terminals 24 together with the terminal base 72 connected to it. The power terminal block 74 includes a first terminal block 741 and a second terminal block 742. The first terminal block 741 and the second terminal block 742 are spaced apart from each other in a first direction x1. The first terminal block 741 supports a portion of the first power terminal 24A, and this supported portion is exposed to the outside of the semiconductor device A10. The second terminal block 742 supports a portion of the second power terminal 24B, and this supported portion is exposed to the outside of the semiconductor device A10. Also, as shown in Figures 8 and 13, nuts 743 are arranged inside the first terminal block 741 and the second terminal block 742, respectively. Each nut 743 corresponds to a connection hole 241 provided in either the first power terminal 24A or the second power terminal 24B in the thickness direction z. Fastening members such as bolts inserted into the connection hole 241 are screwed onto the nut 743.

[0121] As shown in Figures 2, 6, and 9, the output terminal block 75 supports the output terminal 25 together with the terminal base 72 connected to it. The output terminal block 75 includes a first terminal block 751 and a second terminal block 752. The first terminal block 751 and the second terminal block 752 are spaced apart from each other in a first direction x1. The first terminal block 751 supports a portion of the first output terminal 25A, and this supported portion is exposed to the outside of the semiconductor device A10. The second terminal block 752 supports a portion of the second output terminal 25B, and this supported portion is exposed to the outside of the semiconductor device A10. Also, as shown in Figures 9 and 14, nuts 753 are arranged inside the first terminal block 751 and the second terminal block 752, respectively. Each nut 753 corresponds to a connection hole 251 provided in either the first output terminal 25A or the second output terminal 25B in the thickness direction z. Fastening members such as bolts inserted into the connection hole 251 are screwed onto the nut 753.

[0122] As shown in Figures 2, 11, and 12, the top plate 79 covers the internal region of the semiconductor device A10 formed by the heat sink 61 and the case 70. The top plate 79 is supported by a pair of side walls 71 of the case 70, facing the main surface 111 of the substrate 11 and spaced apart from the main surface 111 in the thickness direction z. The top plate 79 is made of an electrically insulating synthetic resin.

[0123] Next, the circuit configuration of semiconductor device A10 will be described based on Figure 21.

[0124] As shown in Figure 21, the semiconductor device A10 has two switching circuits: an upper arm circuit 81 and a lower arm circuit 82. The upper arm circuit 81 consists of a first upper arm mounting layer 211A, a second upper arm mounting layer 221A, and a third upper arm mounting layer 231A, and a plurality of switching elements 31 and a plurality of protection elements 32 electrically connected to these. The plurality of switching elements 31 and the plurality of protection elements 32 electrically connected to these are all connected in parallel between the first power supply terminal 24A and the output terminal 25. The gate electrodes 313 of the plurality of switching elements 31 in the upper arm circuit 81 are all connected in parallel to the first gate terminal 27A. A gate voltage is applied to the first gate terminal 27A by a drive circuit such as a gate driver located outside the semiconductor device A10, and the plurality of switching elements 31 in the upper arm circuit 81 are driven simultaneously.

[0125] The main surface electrodes 311 of the multiple switching elements 31 in the upper arm circuit 81 are all connected in parallel to the first detection terminal 281A. The source current flowing through the multiple switching elements 31 in the upper arm circuit 81 is input to a control circuit located outside the semiconductor device A10 via the first detection terminal 281A.

[0126] In the upper arm circuit 81, the voltages applied to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A by the first power supply terminal 24A and the second power supply terminal 24B are input to the control circuit of the externally located semiconductor device A10 via the power supply current detection terminal 282.

[0127] In the lower arm circuit 82, the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B, along with the multiple switching elements 31 and multiple protection elements 32 electrically connected to them, are all connected in parallel between the output terminal 25 and the second power supply terminal 24B. The gate electrodes 313 of the multiple switching elements 31 in the lower arm circuit 82 are all connected in parallel to the second gate terminal 27B. When a gate voltage is applied to the second gate terminal 27B by a drive circuit such as a gate driver located outside the semiconductor device A10, the multiple switching elements 31 in the lower arm circuit 82 are driven simultaneously.

[0128] The main surface electrodes 311 of the multiple switching elements 31 in the lower arm circuit 82 are all connected in parallel to the second detection terminal 281B. The source current flowing through the multiple switching elements 31 in the lower arm circuit 82 is input to a control circuit located outside the semiconductor device A10 via the second detection terminal 281B.

[0129] When a DC power supply is connected to the first power terminal 24A and the second power terminal 24B, and multiple switching elements 31 in the upper arm circuit 81 and the lower arm circuit 82 are driven, AC voltages of various frequencies are output from the output terminal 25. The AC voltage output from the output terminal 25 is supplied to a power supply target such as a motor.

[0130] Next, we will explain the effects and benefits of semiconductor device A10.

[0131] In the configuration of the semiconductor device A10, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 straddles the space between the mounting layers and the side surface 31C in the thickness direction z. As shown in Figure 22, when moisture penetrates the sealing resin 52 due to the effects of high temperature and high humidity, a leakage current Lc is likely to be generated from the main surface electrode 311 of the switching element 31. In the switching element 31, the leakage current Lc attempts to flow along the surface and side surface 31C of the insulating film 314. By providing the moisture-resistant layer 51, the path of the leakage current Lc becomes longer, making it more difficult for the leakage current Lc to flow. As a result, the leakage current Lc is prevented from reaching the mounting layers, thus preventing damage to the switching element 31 caused by the conduction of the leakage current Lc. Therefore, semiconductor device A10 can exhibit more stable performance under high temperature and high humidity conditions. Furthermore, when the thickness of the switching element 31 and the protection element 32 is relatively thin, such as 150 μm or less, the path of the leakage current Lc becomes shorter. Therefore, applying a voltage of 1,200 V or more to these semiconductor elements makes it easier for the leakage current Lc to flow. Thus, providing a moisture-resistant layer 51 to the relatively thin switching element 31 is particularly effective.

[0132] On the other hand, as shown in Figure 23, in comparative example B10, which does not have a moisture-resistant layer 51, the leakage current Lc is transmitted along the side surface 31C of the switching element 31 to the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231). As a result, a short circuit occurs between the main surface electrode 311 and the back surface electrode 312 of the switching element 31, causing the switching element 31 to be destroyed.

[0133] The moisture-resistant layer 51 preferably contains polyimide as a constituent material. Polyimide is an electrical insulating material that is resistant to temperature cycles and is less susceptible to moisture. By including polyimide in the constituent material, the moisture-resistant layer 51 exhibits the function of making it difficult for leakage current Lc to flow along the side surface 31C of the switching element 31, even under high temperature and high humidity conditions, as shown in Figure 22.

[0134] It is more preferable that the moisture-resistant layer 51 further contains silicone gel in addition to polyimide. By using such a composition, the Young's modulus of the moisture-resistant layer 51 can be reduced compared to a moisture-resistant layer 51 composed solely of polyimide. This makes it easier for the moisture-resistant layer 51 to follow the thermal strain of the switching element 31 that occurs when the semiconductor device A10 is in use. Therefore, the shear stress acting on the switching element 31 can be reduced.

[0135] Furthermore, by making the moisture-resistant layer 51 a structure that includes polyimide and silicone gel, the resistance of the moisture-resistant layer 51 to temperature cycling can be further improved. When a semiconductor device A10 equipped with a moisture-resistant layer 51 composed solely of polyimide was subjected to a temperature cycling test from -40 to 125°C, the semiconductor device A10 was destroyed after approximately 20 cycles. This is thought to be because cracks formed in the moisture-resistant layer 51, allowing moisture to penetrate through these cracks. On the other hand, when a semiconductor device A10 equipped with a moisture-resistant layer 51 composed of polyimide and silicone gel was subjected to the same temperature cycling test, the semiconductor device A10 was not destroyed even after more than 1,000 cycles. This is because, compared to a moisture-resistant layer 51 composed solely of polyimide, the Young's modulus of the moisture-resistant layer 51 is lower, thus reducing the shear stress generated in the moisture-resistant layer 51 due to thermal expansion and contraction. Therefore, it is more preferable for the moisture-resistant layer 51 to be composed of polyimide and silicone gel.

[0136] The semiconductor device A10 includes a plurality of wires 41 connected to the main surface electrode 311 of the switching element 31. The plurality of wires 41 extend in a first direction x1. This allows for the formation of a moisture-resistant layer 51 covering the side surface 31C of the switching element 31 without being obstructed by the plurality of wires 41.

[0137] Each of the first bonding portions 411 of the pair of outer wires 41B has a first connecting portion 411A that contacts the first pad portion 311A, a second connecting portion 411B that contacts the second pad portion 311B, and a connecting portion 411C sandwiched between the first connecting portion 411A and the second connecting portion 411B. The connecting portion 411C protrudes in the thickness direction z toward the side facing the main surface 31A of the switching element 31. As shown in Figures 16 and 19, the height H of the connecting portion 411C, from the surface of the main surface electrode 311 of the switching element 31 to the apex C of the connecting portion 411C in the thickness direction z, is preferably three times or more the diameter of the wire 41. For example, if the diameter of the wire 41 is 300 μm, the height H of the connecting portion 411C is preferably 900 μm or more. As a result, the connecting portion 411C functions as an expandable and contractible body that can elastically deform in the first direction x1, thereby reducing the shear stress acting on the first connecting portion 411A and the second connecting portion 411B. Therefore, it is possible to prevent the first bonding portion 411 from peeling off from the main surface electrode 311 due to this shear stress. In the semiconductor device A10, the diameter of the wire 41 is 400 μm, and the height H of the connecting portion 411C is 1,600 μm. Note that in the semiconductor device A10, if the height H of the connecting portion 411C is 800 μm, the ΔT described later... j During power cycle testing, at least one of the first connection part 411A and the second connection part 411B may delaminate.

[0138] The semiconductor device A10 includes a heat sink 61 bonded to the back surface 112 of the substrate 11. This allows heat generated from the multiple switching elements 31 to be efficiently dissipated to the outside of the semiconductor device A10. In this case, the substrate 11 is preferably made of a ceramic material (such as aluminum nitride) with excellent thermal conductivity.

[0139] Figures 24 to 50 show semiconductor devices A11 to A15, which are modified versions of semiconductor device A10.

[0140] (First variation) Based on Figures 24 and 25, a semiconductor device A11 according to the first modified example of semiconductor device A10 will be described. Semiconductor device A11 is an example in which the contact area of ​​the moisture-resistant layer 51 with the switching element 31 is smaller than that of the aforementioned semiconductor device A10. Note that the cross-sectional position in Figure 24 is the same as the cross-sectional position in Figure 16. The cross-sectional position in Figure 25 is the same as the cross-sectional position in Figure 19.

[0141] As shown in Figures 24 and 25, the moisture-resistant layer 51 covers a portion of the side surface 31C of the switching element 31.

[0142] Next, we will explain the effects and benefits of semiconductor device A11.

[0143] According to the configuration of semiconductor device A11, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 spans between the mounting layers and the side surface 31C in the thickness direction z. Therefore, semiconductor device A11 can also exhibit more stable performance under high temperature and high humidity conditions.

[0144] (Second variation) Based on Figures 26 to 31, a semiconductor device A12, which is a second modified example of semiconductor device A10, will be described. Semiconductor device A12 is an example in which the contact area of ​​the moisture-resistant layer 51 with the switching element 31 is larger than the contact area of ​​the aforementioned semiconductor device A10.

[0145] As shown in Figures 26 to 31, in the switching element 31, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314. The moisture-resistant layer 51 straddles the peripheral edge 314A of the insulating film 314 when viewed in the thickness direction z.

[0146] Next, we will explain the effects and benefits of semiconductor device A12.

[0147] According to the configuration of semiconductor device A12, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 spans between the mounting layers and the side surface 31C in the thickness direction z. Therefore, semiconductor device A12 can also exhibit more stable performance under high temperature and high humidity conditions.

[0148] In the switching element 31 of the semiconductor device A12, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314. The moisture-resistant layer 51 straddles the peripheral edge 314A of the insulating film 314 when viewed in the thickness direction z. As a result, the path of the leakage current Lc shown in Figure 22 is even longer than that of the semiconductor device A10, making it more difficult for the leakage current Lc to flow than in the semiconductor device A10. In addition, since the moisture-resistant layer 51 covers the insulating film 314, the insulating film 314 can be protected from external factors.

[0149] (Third variation) Based on Figures 32 to 37, a semiconductor device A13, which is a third modified example of semiconductor device A10, will be described. Semiconductor device A13 is an example in which the contact area of ​​the moisture-resistant layer 51 with respect to the switching element 31 is larger than that of the aforementioned semiconductor device A12.

[0150] As shown in Figures 32 to 37, in the switching element 31, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314. The moisture-resistant layer 51 straddles the peripheral edge 314A of the insulating film 314 when viewed in the thickness direction z. In addition, the moisture-resistant layer 51 is in contact with at least a portion of the main surface electrode 311.

[0151] Next, we will explain the effects and benefits of semiconductor device A13.

[0152] According to the configuration of semiconductor device A13, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 spans between the mounting layers and the side surface 31C in the thickness direction z. Therefore, semiconductor device A13 can also exhibit more stable performance under high temperature and high humidity conditions.

[0153] In the switching element 31 of the semiconductor device A13, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314, as well as with at least a portion of the main surface electrode 311. As shown in Figures 32 and 35, when viewed from the thickness direction z, the moisture-resistant layer 51 overlaps with a portion of the main surface electrode 311 and surrounds the main surface electrode 311. As a result, the dielectric breakdown voltage of the side surface 31C is improved compared to the semiconductor device A12, and the leakage current Lc shown in Figure 22 is less likely to flow than in the semiconductor device A12. In addition, since the moisture-resistant layer 51 covers the insulating film 314, the insulating film 314 can be protected from external factors.

[0154] (Fourth variation) Based on Figures 38 to 43, a semiconductor device A14, which is a fourth modified example of semiconductor device A10, will be described. Semiconductor device A14 is an example in which the contact area of ​​the moisture-resistant layer 51 with respect to the switching element 31 is larger than that of the aforementioned semiconductor device A13.

[0155] As shown in Figures 38 to 43, in the switching element 31, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314. The moisture-resistant layer 51 straddles the peripheral edge 314A of the insulating film 314 when viewed in the thickness direction z. The moisture-resistant layer 51 is also in contact with the main surface electrode 311 and at least a portion of the first bonding portion 411 of the plurality of wires 41. Therefore, the plurality of switching elements 31 are completely covered by the moisture-resistant layer 51. However, since the first bonding portion 411 is not completely covered by the moisture-resistant layer 51, the upper end of the first bonding portion 411 is exposed from the moisture-resistant layer 51. That is, the thickness of the moisture-resistant layer 51 covering the main surface 31A of the switching element 31 is smaller than the diameter of the wire 41.

[0156] As shown in Figures 38, 39, 41, and 42, the moisture-resistant layer 51 covers the entire surface of the protective element 32 corresponding to the switching element 31. However, the second bonding portions 412 of the multiple wires 41 are not completely covered by the moisture-resistant layer 51, so the upper ends of the second bonding portions 412 are exposed from the moisture-resistant layer 51. That is, the thickness of the moisture-resistant layer 51 covering the main surface 32A of the protective element 32 is less than the diameter of the wires 41.

[0157] Next, an example of a method for forming the moisture-resistant layer 51 of the semiconductor device A14 will be described. A synthetic resin material containing polyimide, silicone gel, and a solvent, and having fluidity, is prepared. The solvent is volatile. Then, after electrically connecting the multiple switching elements 31 and multiple protective elements 32 to the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) on which they are mounted, etc., by a wire bonding process, the synthetic resin material is dropped onto the upper surfaces of the switching elements 31 and protective elements 32 using a dispenser. Because the synthetic resin is fluid, it spreads over the entire upper surface of the switching element 31, including the main surface electrode 311, gate electrode 313, and insulating film 314, and also spreads from the side surface 31C of the switching element 31 to the mounting layer. Similarly, the entire surface of the protective element 32 is covered with the synthetic resin material. As a result, the entire surface of the switching element 31 is covered with the synthetic resin material. Due to the surface tension of the synthetic resin material, the thickness of the synthetic resin material on the upper surface of the switching element 31 becomes substantially uniform. Finally, the moisture-resistant layer 51 is formed by heat curing the synthetic resin material. At this time, the solvent evaporates. This formation method makes it easy to construct the moisture-resistant layer 51 that covers the switching element 31 and the protective element 32.

[0158] Next, we will explain the effects and benefits of semiconductor device A14.

[0159] According to the configuration of semiconductor device A14, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 spans between the mounting layers and the side surface 31C in the thickness direction z. Therefore, semiconductor device A14 can also exhibit more stable performance under high temperature and high humidity conditions.

[0160] In each of the multiple switching elements 31, the moisture-resistant layer 51 is in contact with both the side surface 31C and the insulating film 314. Furthermore, the moisture-resistant layer 51 is also in contact with the main surface electrode 311 and at least a portion of the first bonding portion 411 of the multiple wires 41. As a result, the entire switching element 31 is covered with the moisture-resistant layer 51, which suppresses moisture that has penetrated the sealing resin 52 from reaching the surface of the switching element 31. Therefore, dielectric breakdown of the multiple switching elements 31 caused by the leakage current Lc shown in Figure 22 due to the influence of moisture can be prevented more effectively. In addition, since the moisture-resistant layer 51 covers the insulating film 314, the insulating film 314 can be protected from external factors.

[0161] In each of the multiple switching elements 31, a pair of outer wires 41B having connecting portions 411C of a first bonding portion 411 that protrudes in the thickness direction z are arranged on both sides of a pair of inner wires 41A in the second direction x2. This allows the synthetic resin material for forming the moisture-resistant layer 51 to be dropped from above the main surface 31A of the switching element 31 without interfering with the connecting portions 411C. As shown in Figure 38, in the semiconductor device A14, the connecting portions 411C are provided only on the first bonding portions 411 of the pair of outer wires 41B. It is also conceivable to provide the connecting portions 411C not only on the first bonding portions 411 of the pair of outer wires 41B but also on the first bonding portions 411 of the pair of inner wires 41A. However, in this case, the two adjacent connecting portions 411C are closer together, making it difficult to drop the synthetic resin material for forming the moisture-resistant layer 51 onto the switching element 31. Furthermore, when the synthetic resin material is dropped onto the switching element 31, there is a risk that the synthetic resin material may creep up to the upper end of the connecting portion 411C. In this state, because the Young's modulus of the moisture-resistant layer 51 is relatively high, a large shear stress acts on the connecting portion 411C due to the heat emitted from the switching element 31. As a result, there is a risk that the first connection portion 411A and the second connection portion 411B of the first bonding portion 411 will peel off from the main surface electrode 311 of the switching element 31. Therefore, from the viewpoint of the reliability of the semiconductor device A14, it is preferable to ensure a longer distance between two adjacent connecting portions 411C in the second direction x2.

[0162] The moisture-resistant layer 51 also covers the entire protective element 32 corresponding to the switching element 31 it covers. This allows for more effective protection of multiple protective elements 32 from external factors. However, since the first bonding portion 411 is not completely covered by the moisture-resistant layer 51, the upper end of the first bonding portion 411 is exposed from the moisture-resistant layer 51. That is, the thickness of the moisture-resistant layer 51 covering the main surface 31A of the switching element 31 is smaller than the diameter of the wire 41. This prevents the shear stress acting on the first bonding portion 411 from becoming excessively large compared to the case where the first bonding portion 411 is completely covered by the moisture-resistant layer 51. Therefore, the reliability of the semiconductor device A14 is improved because the delamination of the first bonding portion 411 from the main surface electrode 311 of the switching element 31 can be suppressed.

[0163] Next, based on Figure 50, the preferred thickness of the moisture-resistant layer 51 in semiconductor device A14 will be described. Figure 50 shows the H3TRB test results and ΔT based on the difference in the thickness of the moisture-resistant layer 51 in semiconductor device A14. j The power cycle test results are shown. The thickness of the moisture-resistant layer 51 shown in Figure 50 refers to the thickness of the moisture-resistant layer 51 at the corners of the insulating film 314 of the switching element 31 (the portion connected to both the peripheral edge 314A and the side surface 31C). In the H3TRB test, the semiconductor device A14 was subjected to a temperature cycle of -40 to 125°C before the test was performed. The number of temperature cycles was 300. The DC voltage used to drive the semiconductor device A14 in the H3TRB test was 1,360V, as described later. ΔT j In power cycle testing, the temperature ΔT of the first bonding layer 391 for electrically bonding multiple switching elements 31 to the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) is measured. j This is set to 100℃. As a result, ΔT j The temperature cycle range in power cycle testing is 50 to 150°C.

[0164] The vertical axis on the left side of FIG. 50 indicates the endurance time of the semiconductor device A14 in the H3TRB test. The endurance time is the time from the start of the test until at least one of the switching elements 31 of the semiconductor device A14 reaches dielectric breakdown. The vertical axis on the right side of FIG. 50 is the number of temperature cycles (ΔT j when the first bonding portion 411 of the wire 41 connected to the main surface electrode 311 of the switching element 31 is peeled off from the main surface electrode 311 by a power cycle test (ΔT j power cycle). The required number of such temperature cycles (ΔT j standard value of the power cycle shown in FIG. 50) is 15,000 times. The horizontal axis of FIG. 50 is the thickness of the moisture-proof layer 51.

[0165] As shown in FIG. 50, when the thickness of the moisture-proof layer 51 exceeds 10 μm, the endurance time of the semiconductor device A14 rapidly increases. This indicates that the greater the thickness of the moisture-proof layer 51, the higher the breakdown resistance (moisture absorption reliability) of the switching element 31 due to the ingress of moisture. On the other hand, when the thickness of the moisture-proof layer 51 is gradually increased, ΔT j the power cycle gradually decreases. This indicates that the greater the thickness of the moisture-proof layer 51, the easier it is for the first bonding portion 411 of the wire 41 to peel off from the main surface electrode 311 of the switching element 31, or the easier it is for the second bonding portion 412 of the wire 41 to peel off from the anode electrode 321 of the protection element 32. Based on these test results, the thickness of the moisture-proof layer 51 is preferably 40 μm or more and 200 μm or less. More preferably, the thickness of the moisture-proof layer 51 is 50 μm or more and 100 μm or less. It has been experimentally confirmed that the thickness of the moisture-proof layer 51 on the upper surface of the switching element 31 is 1.2 times the thickness at the corner of the moisture-proof layer 51. Therefore, the thickness of the moisture-proof layer 51 on the upper surface of the switching element 31 is preferably 48 μm or more and 240 μm or less, and more preferably 60 μm or more and 120 μm or less.

[0166] Figure 51 shows the test results (in hours) of the H3TRB test performed on semiconductor device A14 and comparative example B10, which does not have the moisture-resistant layer 51 shown in Figure 23. As mentioned above, semiconductor devices that pass the H3TRB test (device endurance time of 1,000 hours or more) are expected to exhibit more stable performance under high temperature and high humidity conditions. When performing the H3TRB test with a rated voltage of 1,700V, the DC voltage used to drive both semiconductor device A14 and comparative example B10 in the test is set to 1,360V (80% of the rated voltage). Based on this DC voltage, the H3TRB test results showed that the device endurance time of semiconductor device A14 was 1,000 hours or more, thus passing the test. Therefore, semiconductor device A14 is expected to exhibit more stable performance under high temperature and high humidity conditions. On the other hand, the device endurance time of comparative example B10 was 10 to 500 hours, which is a failure. Therefore, in terms of exhibiting more stable performance under high temperature and high humidity conditions, comparative example B10 can be said to be inferior to semiconductor device A14.

[0167] As shown in Figure 51, the reduction in insulation resistance (in %) of the sealing resin 52 when the H3TRB test was performed was 20% for semiconductor device A14 and 84% for comparative example B10. Even if moisture penetrates the sealing resin 52 under high temperature and high humidity conditions, the moisture-resistant layer 51 makes it difficult for the leakage current Lc shown in Figure 22 to flow along the side surfaces 31C of the multiple switching elements 31, which is why the reduction in insulation resistance of the sealing resin 52 is as shown in Figure 51.

[0168] (Fifth variation) Based on Figures 44 to 49, a semiconductor device A15, which is a fifth modified example of semiconductor device A10, will be described. Semiconductor device A15 is an example in which the thickness of the moisture-resistant layer 51 on the upper surface of the switching element 31 is greater than the thickness of the aforementioned semiconductor device A14.

[0169] As shown in Figures 44 to 49, in the case of multiple switching elements 31, the moisture-resistant layer 51 covers both the multiple switching elements 31 and the first bonding portion 411 of the multiple wires 41.

[0170] As shown in Figures 44, 45, 47, and 48, the moisture-resistant layer 51 covers the entire surface of the protective element 32 corresponding to the switching element 31 and the second bonding portion 412 of the multiple wires 41 connected to the anode electrode 321 of the protective element 32.

[0171] Next, we will explain the effects and benefits of semiconductor device A15.

[0172] According to the configuration of semiconductor device A15, the moisture-resistant layer 51 is in contact with both the mounting layers (first mounting layer 211, second mounting layer 221, and third mounting layer 231) and the side surface 31C of at least one of the switching elements 31. The moisture-resistant layer 51 spans between the mounting layers and the side surface 31C in the thickness direction z. Therefore, semiconductor device A15 can also exhibit more stable performance under high temperature and high humidity conditions.

[0173] In the switching element 31, the moisture-resistant layer 51 covers both the switching element 31 and the first bonding portion 411 of the multiple wires 41. As a result, the entire switching element 31 is covered by the moisture-resistant layer 51, which suppresses moisture that has penetrated the sealing resin 52 from reaching the main surface 31A of the switching element 31. Therefore, dielectric breakdown of the multiple switching elements 31 caused by the leakage current Lc shown in Figure 22 due to the influence of moisture can be prevented more effectively. In addition, since the moisture-resistant layer 51 covers the insulating film 314, the insulating film 314 can be protected from external factors. In the semiconductor device A15 as well, it is preferable that the thickness of the moisture-resistant layer 51 on the upper surface of the switching element 31 be 48 μm or more and 240 μm or less.

[0174] [Second Embodiment] A semiconductor device A20 according to a second embodiment of the present invention will be described based on Figures 52 to 57. In these figures, elements that are the same as or similar to those in the semiconductor device A10 described above are denoted by the same reference numerals, and redundant explanations are omitted.

[0175] The semiconductor device A20 differs from the aforementioned semiconductor device A10 in that it has multiple clips 47 instead of multiple wires 41.

[0176] As shown in Figures 52 to 54, the multiple clips 47 are electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and to one of the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B. As shown in Figures 55 to 57, the multiple clips 47 are electrically connected to the main surface electrodes 311 of the multiple switching elements 31 and to one of the first conductive layer 212, the second conductive layer 222, and the third conductive layer 232. The multiple clips 47 are made by bending thin metal sheets such as copper. As shown in Figures 52 and 55, the multiple clips 47 are strip-shaped, extending in a first direction x1 when viewed from the thickness direction z. As shown in Figures 53 and 56, the multiple clips 47 are hook-shaped when viewed from a second direction x2. Furthermore, as shown in Figures 53 and 56, a clip bonding layer 49 is used to electrically connect the clip 47 to an object such as the main surface electrode 311. The clip bonding layer 49 is conductive. The constituent material of the clip bonding layer 49 is, for example, lead-free solder mainly composed of tin. When the clip bonding layer 49 is used, a plating layer of nickel or gold is applied to the surface of the main surface electrode 311. In the semiconductor device A20, if the main surface electrode 311 is covered with a moisture-resistant layer 51, the clip bonding layer 49 and the plating layer are also covered with the moisture-resistant layer 51.

[0177] As shown in Figures 52 to 54, in the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the first lower arm mounting layer 211B. As shown in Figures 55 to 57, in the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the first conductive layer 212. As a result, the main surface electrodes 311 of the multiple switching elements 31 electrically connected to the first mounting layer 211 are conductive to either the first lower arm mounting layer 211B or the first conductive layer 212.

[0178] As shown in Figures 52 to 54, in the multiple switching elements 31 electrically connected to the second upper arm mounting layer 221A, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the second lower arm mounting layer 221B. As shown in Figures 55 to 57, in the multiple switching elements 31 electrically connected to the second lower arm mounting layer 221B, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the second conductive layer 222. As a result, the main surface electrodes 311 of the switching elements 31 electrically connected to the second mounting layer 221 are conductive to either the second lower arm mounting layer 221B or the second conductive layer 222.

[0179] As shown in Figures 52 to 54, in the multiple switching elements 31 electrically connected to the third upper arm mounting layer 231A, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the third lower arm mounting layer 231B. As shown in Figures 55 to 57, in the multiple switching elements 31 electrically connected to the third lower arm mounting layer 231B, the multiple clips 47 are electrically connected to the multiple main surface electrodes 311 and the third conductive layer 232. As a result, the main surface electrodes 311 of the switching elements 31 electrically connected to the third mounting layer 231 are electrically connected to either the third lower arm mounting layer 231B or the third conductive layer 232.

[0180] Based on Figures 52 and 53, the configuration of the clips 47 in each of the multiple switching elements 31 electrically connected to the first upper arm mounting layer 211A, the second upper arm mounting layer 221A, and the third upper arm mounting layer 231A will be described. As shown in Figure 53, the clips 47 are also electrically connected to the anode electrode 321 of the protective element 32 corresponding to the switching element 31 using a clip connection layer 49. As a result, the anode electrode 321 of the protective element 32 electrically connected to the first upper arm mounting layer 211A is conductive to both the main surface electrode 311 of the corresponding switching element 31 and the first lower arm mounting layer 211B. The anode electrode 321 of the protective element 32 electrically connected to the second upper arm mounting layer 221A is conductive to both the main surface electrode 311 of the corresponding switching element 31 and the second lower arm mounting layer 221B. Furthermore, the anode electrode 321 of the protective element 32, which is electrically connected to the third upper arm mounting layer 231A, is electrically connected to both the main surface electrode 311 of the corresponding switching element 31 and the third lower arm mounting layer 231B.

[0181] As shown in Figures 52 and 53, each of the multiple clips 47 has an opening 471 that penetrates in the thickness direction z. The opening 471 is located between the main surface electrode 311 of the switching element 31 and the anode electrode 321 of the protective element 32 in the first direction x1. Viewed from the thickness direction z, the periphery 314A of the insulating film 314 of the switching element 31 is visible through the opening 471. When the multiple clips 47 are electrically joined to the main surface electrodes 311 of the multiple switching elements 31, a large portion of the switching elements 31 is covered by the clips 47. Therefore, by providing an opening 471 in each of the multiple clips 47 at a position that overlaps with the switching element 31 when viewed from the thickness direction z, the synthetic resin material for forming the moisture-resistant layer 51 can be dripped even below the clips 47. This allows the synthetic resin material to be dripped evenly over the entire switching element 31. In semiconductor device A20, the configuration shown includes an opening 471 in the clip 47. However, instead of the opening 471, a notch that penetrates the clip 47 in the thickness direction z may be provided at a position that overlaps with the switching element 31 when viewed from the thickness direction z.

[0182] Based on Figures 55 and 56, the configuration of the clips 47 in each of the multiple switching elements 31 electrically connected to the first lower arm mounting layer 211B, the second lower arm mounting layer 221B, and the third lower arm mounting layer 231B will be described. As shown in Figure 56, the clips 47 are also electrically connected to the anode electrode 321 of the protective element 32 corresponding to the switching element 31 using a clip connection layer 49. As a result, the anode electrode 321 of the protective element 32 electrically connected to the first lower arm mounting layer 211B is conductive to both the main surface electrode 311 of the corresponding switching element 31 and the first conductive layer 212. The anode electrode 321 of the protective element 32 electrically connected to the second lower arm mounting layer 221B is conductive to both the main surface electrode 311 of the corresponding switching element 31 and the second conductive layer 222. Furthermore, the anode electrode 321 of the protective element 32, which is electrically connected to the third lower arm mounting layer 231B, is electrically connected to both the main surface electrode 311 of the corresponding switching element 31 and the third conductive layer 232. Since the clip 47 is electrically connected to the anode electrode 321, the pair of auxiliary wires 46 shown in Figure 18 are not connected to the anode electrode 321 in the semiconductor device A20.

[0183] As shown in Figures 55 and 56, each of the multiple clips 47 has a pair of openings 471 that penetrate in the thickness direction z. The pair of openings 471 are located on both sides of the main surface electrode 311 of the switching element 31 in a first direction x1. Viewed from the thickness direction z, the periphery 314A of the insulating film 314 of the switching element 31 is visible through the pair of openings 471.

[0184] Next, we will explain the effects and benefits of semiconductor device A20.

[0185] In the configuration of semiconductor device A20, the moisture-resistant layer 51 is in contact with both one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231, and the side surfaces 31C of the multiple switching elements 31. The moisture-resistant layer 51 spans between one of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 and the side surfaces 31C in the thickness direction z. Therefore, semiconductor device A20 can also exhibit more stable performance under high temperature and high humidity conditions.

[0186] In semiconductor device A20, the configuration of the moisture-resistant layer 51 is the same as that in semiconductor device A10. However, in semiconductor device A20 as well, the configuration of the moisture-resistant layer 51 may be the same as those shown in semiconductor devices A11 to A15 described above.

[0187] The semiconductor device A20 includes multiple clips 47 that replace multiple wires 41. The cross-sectional area of ​​the clips 47 (cross-sectional area along the second direction x2) is larger than the cross-sectional area of ​​the multiple wires 41. As a result, the electrical resistance of the clips 47 is lower than that of the multiple wires 41. Therefore, the parasitic resistance of the semiconductor device A20 is lower than that of the semiconductor device A10, and thus the power loss of the semiconductor device A20 can be suppressed more than that of the semiconductor device A10.

[0188] Since the cross-sectional area of ​​the clip 47 is larger than the cross-sectional area of ​​the multiple wires 41, heat is more easily conducted in the first direction x1 by the clip 47 than by the multiple wires 41. This allows the heat generated from the multiple switching elements 31 to be diffused more efficiently. For example, in the first substrate 11A, heat generated from the multiple switching elements 31 tends to accumulate in the first upper arm mounting layer 211A, which constitutes the upper arm circuit 81 shown in Figure 21. Therefore, the multiple clips 47 can efficiently diffuse the heat accumulated in the first upper arm mounting layer 211A to the first lower arm mounting layer 211B and the first conductive layer 212.

[0189] The number of switching elements 31 electrically connected to each of the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 can be freely set according to the required power conversion. Furthermore, as mentioned above, the first mounting layer 211, the second mounting layer 221, and the third mounting layer 231 are examples of the "mounting layers" described in the claims of the present invention, but the number of regions of the "mounting layers" is not limited to six as in the present invention, and can be freely set.

[0190] In the description of the embodiments above, an example was shown in which the switching element 31 and the protective element 32 connected in antiparallel to the switching element 31 are covered with a moisture-resistant layer 51. However, in a semiconductor device that uses the switching element 31 alone without using the protective element 32 (a configuration that does not use an external freewheeling diode), the switching element 31 may be covered with the moisture-resistant layer 51. Furthermore, the present invention is applicable not only to switching elements but also to rectifier elements. For example, the present invention can be applied to a semiconductor device that includes multiple Schottky barrier diodes. In this case, the material, thickness, and formation area of ​​the moisture-resistant layer 51 are the same as in the embodiments above.

[0191] Furthermore, in the description of the embodiments described above, a semiconductor device is given as an example, comprising a substrate 11 on which a conductor (mounting layer and conductive layer) made of a thin metal film is arranged, and a plurality of switching elements 31 are electrically bonded to the conductor. The present invention is not limited to this example, but can also be applied to a resin package type semiconductor device that comprises a lead frame, to which switching elements or rectifier elements are electrically bonded and molded. In such a semiconductor device as well, since there is a risk of moisture entering through the sealing resin, the same effect can be obtained by covering the entire surface or sides of the switching elements or rectifier elements with the moisture-resistant layer according to the present invention. In addition, even in a resin package type semiconductor device, a connection structure by wire bonding composed of wires 41, as in semiconductor device A10, or a connection structure by thin metal plates composed of clips 47, as in semiconductor device A20, can be applied.

[0192] The present invention is not limited to the embodiments described above. The specific configuration of each part of the present invention can be modified in various ways.

[0193] In addition to the configuration described in the claims, the present invention includes at least the configurations described below. [Note 1] The first conductive layer and A second conductive layer spaced apart from the first conductive layer, A semiconductor element having a semiconductor layer, a main surface electrode provided on the upper surface of the semiconductor layer, and a back surface electrode provided on the lower surface of the semiconductor layer, and mounted on the first conductive layer, wherein the back surface electrode is electrically connected to the first conductive layer, A connection structure electrically connected to the main surface electrode and the second conductive layer, A first insulating layer covering at least the side surface of the semiconductor element, The invention comprises a second insulating layer covering the first insulating layer, A semiconductor device characterized in that the first insulating layer is made of a material with lower moisture permeability than the second insulating layer. The first insulating layer also functions as a barrier film that prevents moisture from entering. [Note 2] The semiconductor device described in Appendix 1, wherein the first insulating layer covers the entire semiconductor element. [Note 3] The connection structure has a connection portion that contacts the main surface electrode, The semiconductor device according to Appendix 1, wherein the first insulating layer covers the entire semiconductor element excluding the connection portion. [Note 4] The thickness of the first insulating layer at the corner located between the upper surface and the side surface of the semiconductor element is 40 μm or more and 200 μm or less. The semiconductor device according to Appendix 1, wherein the thickness of the first insulating layer on the upper surface of the semiconductor element is 48 μm or more and 240 μm or less. [Note 5] The thickness of the first insulating layer at the corner located between the upper surface and the side surface of the semiconductor element is 50 μm or more and 100 μm or less. The semiconductor device according to Appendix 4, wherein the thickness of the first insulating layer on the upper surface of the semiconductor element is 60 μm or more and 120 μm or less. [Note 6] The aforementioned connection structure includes a connection structure using wires. The semiconductor device according to Appendix 1, wherein the thickness of the first insulating layer on the upper surface of the semiconductor element is smaller than the diameter of the wire. [Note 7] The wire has a connecting portion that contacts the main surface electrode, The semiconductor device according to Appendix 6, wherein the thickness of the first insulating layer on the upper surface of the semiconductor element is less than the height of the connection portion (the distance from the surface of the main surface electrode to the top of the connection portion). That is, the top of the connection portion is exposed from the first insulating layer. Note that the height of the connection portion is less than the diameter of the wire because the connection portion is crushed by a wedge tool during bonding. [Note 8] The semiconductor device described in Appendix 1, wherein the thickness of the semiconductor layer is 400 μm or less. [Note 9] The semiconductor device described in Appendix 8, wherein the thickness of the semiconductor layer is 150 μm or less. [Note 10] The semiconductor device described in Appendix 1 further comprises a breakdown structure having an insulating layer that covers the upper surface of the semiconductor layer and surrounds the periphery of the main surface electrode, wherein the first insulating layer covers the breakdown structure. In the breakdown structure, an oxide film or a nitride film is formed on the semiconductor layer, and a layer such as a polyimide layer or a polybenzoxazole is formed thereon as the insulating layer. [Note 11] The semiconductor device according to Appendix 1, wherein the first insulating layer comprises a synthetic resin which is either polyimide or polybenzoxazole. [Note 12] The semiconductor device according to Appendix 11, wherein the first insulating layer comprises a silicone gel. [Note 13] The semiconductor device according to Appendix 12, wherein in the configuration of the first insulating layer, the synthetic resin and the silicone gel are uniformly dispersed. [Note 14] The semiconductor device according to Appendix 12 or 13, wherein, in the configuration of the first insulating layer, the weight content ratio of the synthetic resin to the silicone gel is such that the synthetic resin is greater. [Note 15] The semiconductor device according to Appendix 14, wherein, in the configuration of the first insulating layer, the weight content ratio of the synthetic resin to the silicone gel is 1.5 to 7.0 for the synthetic resin, with the silicone gel being 1. [Note 16] The semiconductor device described in Appendix 1, wherein the connection structure includes a wire connection structure and a thin metal plate connection structure. [Note 17] The semiconductor device described in Appendix 1, wherein the semiconductor layer is composed of a semiconductor material mainly consisting of silicon carbide. [Note 18] The semiconductor device described in Appendix 17 includes a MOSFET or a Schottky barrier diode. [Note 19] The semiconductor device described in Appendix 1, wherein the breakdown voltage of the semiconductor element is 1,200V or higher. [Note 20] The first conductive layer and the second conductive layer are composed of a lead frame. The semiconductor device according to Appendix 1, wherein the second insulating layer includes a package resin that seals the first conductive layer, the second conductive layer, the semiconductor element, and the connection structure. [Note 21] The first conductive layer and the second conductive layer are metal layers disposed on an insulating substrate. The semiconductor device according to Appendix 1, wherein the second insulating layer includes a sealing resin that seals the insulating substrate, the first conductive layer, the second conductive layer, the semiconductor element, and the connection structure. The sealing resin includes silicone gel. [Note 22] The semiconductor device described in Appendix 1, wherein the surface of the second insulating layer is exposed to the outside air (atmosphere). [Note 23] A method for manufacturing a semiconductor device as described in any of Appendix 1 to 22, A step of preparing a synthetic resin material containing a material or its precursor that has lower moisture permeability than the material constituting the second insulating layer, and a volatile solvent, A step of electrically connecting the back electrode to the first conductive layer, A step of covering the semiconductor element with the synthetic resin material by dropping the synthetic resin material onto the upper surface of the semiconductor element, A method for manufacturing a semiconductor device, comprising the steps of: covering the semiconductor element with the synthetic resin material and then thermally curing the synthetic resin material. This forms the first insulating layer. Note that, prior to the step of thermally curing the synthetic resin material, the synthetic resin material does not need to have the function of the first insulating layer; it is sufficient that it has the function of the first insulating layer after thermal curing. For example, polyimide is dissolved in the solvent in a precursor state, and after thermal curing, it becomes polyimide through imidation, and then exhibits the function of the first insulating layer. [Note 24] The method for manufacturing a semiconductor device according to Appendix 23, further comprising the step of connecting the connection structure to the main surface electrode and the second conductive layer before the step of covering the semiconductor element with the synthetic resin material. [Explanation of symbols]

[0194] A10, A20: Semiconductor equipment 11: Circuit board 11A: First board 11B: 2nd board 11C: 3rd board 111: Main surface 112: Back side 211: First layer 211A: First upper arm mounting layer 211B: Layer with first lower arm 211C: First power pad 212: First conductive layer 212A: Second power pad 213: First Gate Layer 213A: First upper arm gate layer 213B: First lower arm gate layer 214: First detection layer 214A: First upper arm detection layer 214B: First lower arm detection layer 215: Thermistor-equipped layer 221: Second layer 221A: Second upper arm mounting layer 221B: Second lower arm mounting layer 221C: Output Pad 222: Second conductive layer 223: Second Gate Layer 223A: Second upper arm gate layer 223B: Second lower arm gate layer 224: Second detection layer 224A: Second upper arm detection layer 224B: Second lower arm detection layer 231: Third layer 231A: Third upper arm mounting layer 231B: Third lower arm mounting layer 232: Third conductive layer 233: Third Gate Layer 233A: Third upper arm gate layer 233B: Third Lower Arm Gate Layer 234: Third detection layer 234A: Third upper arm detection layer 234B: Third lower arm detection layer 24: Power terminal 24A: 1st power supply terminal 24B: 2nd power supply terminal 241: Connection port 242: Connecting member 25: Output terminal 25A: First output terminal 25B: Second output terminal 251: Connection hole 252: Connecting member 261: Intermediate conductive member 261A: First component 261B: Second component 261C: Third member 262: First conductive member 263: Second conductive member 27: Gate terminal 27A: First gate terminal 27B: Second gate terminal 281: Element current detection terminal 281A: First detection terminal 281B: Second detection terminal 282: Power supply current detection terminal 29: Thermistor terminal 31: Switching element 31A: Main surface 31B: Back side 31C: Side 311: Main surface electrode 311A: First pad section 311B: Second pad section 312: Back surface electrode 313: Grid gate 314: Insulating film 314A: Periphery 32: Protective element 32A: Main surface 32B: Back side 32C: Side 321: Anode electrode 322: Cathode electrode 323: Insulating film 33: Thermistor 391: 1st bonding layer 392:Second bonding layer 41: Wire 41A: Internal wire 41B: Outer wire 411: Bonding Section 1 411A: First connection section 411B: Second connection section 411C: Connection part 412: Bonding Section 2 421: First gate wire 422: Second gate wire 431: First detection wire 432: Second detection wire 44: Power supply current detection wire 45: Thermistor wire 46: Auxiliary wire 47: Clip 471: Opening 49: Clip bonding layer 51: Moisture-resistant layer 52: Sealing resin 61: Heat sink 611: Support hole 62: Heat transfer layer 69: Substrate bonding layer 70: Case 71: Side wall 72: Terminal pedestal 73: Mounting part 731: Mounting hole 74: Power supply terminal block 741: First terminal block 742: Second terminal block 743: Nut 75: Output terminal block 751: First terminal block 752: Second terminal block 753: Nut 79: Top plate 81: Upper arm circuit 82: Lower arm circuit z: Thickness direction x1: First direction x2: Second direction

Claims

1. A first conductive layer having a main surface facing one side in the thickness direction, A first bonding layer, which is a conductor and is placed on the main surface, A first element having a first surface facing the same side as the main surface in the thickness direction, a second surface facing the opposite side from the first surface in the thickness direction, and a third surface connected to each of the first and second surfaces, wherein the second surface is bonded to the main surface via the first bonding layer, A conductive member electrically connected to the first surface, A first insulating layer covering at least the first and third surfaces, The first bonding layer extends from the main surface to the second surface and has sides that define the outer shape of the first bonding layer. The first insulating layer is in contact with the main surface and the side surface, A semiconductor device in which, in a cross-section with the thickness direction as the in-plane direction, the first insulating layer straddles the boundary between the main surface and the side surface.

2. The semiconductor device according to claim 1, wherein the first insulating layer comprises a silicone gel.

3. The semiconductor device according to claim 2, wherein the first insulating layer comprises a synthetic resin which is either polyimide or polybenzoxazole.

4. The semiconductor device according to claim 3, wherein, in the configuration of the first insulating layer, the weight of the synthetic resin is greater than the weight of the silicone gel.

5. The semiconductor device according to claim 4, wherein, in the configuration of the first insulating layer, the weight content ratio of the synthetic resin to the silicone gel is 1.5 to 7.0 for the synthetic resin, with the silicone gel being 1.

6. The semiconductor device according to any one of claims 1 to 5, wherein the first insulating layer covers the entirety of the elements that define the outer shape of the first element, excluding the second surface.

7. The semiconductor device according to claim 6, wherein the conductive member includes a portion covered by the first insulating layer.

8. The semiconductor device according to claim 6 or 7, wherein, in a cross-section with the thickness direction as the in-plane direction, the dimensions of the first insulating layer in a direction perpendicular to the thickness direction gradually decrease from the second surface to the first surface.

9. The semiconductor device according to any one of claims 1 to 8, wherein the conductive member is a wire.

10. The semiconductor device according to any one of claims 1 to 9, wherein the first element is composed of a semiconductor material mainly composed of silicon carbide.

11. A semiconductor device according to any one of claims 1 to 10, further comprising a sealing resin covering at least the first insulating layer among the first element and the first insulating layer and the conductive member.

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