JP2020181912A - Semiconductor device - Google Patents

Abstract

To downsize a power substrate.SOLUTION: A semiconductor device 10 comprises a heat sink 11, a power substrate 20, a control substrate, and a capacitor substrate 50. The semiconductor device 10 also comprises a plurality of power elements. The plurality of power elements are separated into six power element groups and arranged. In each power element group, each power element comes into line. Each power element group is arranged at intervals. The semiconductor device 10 further comprises a spacer 40 electrically connecting the power substrate 20 and the capacitor substrate 50. The spacer 40 comprises a main body 41 and a heat transfer unit 42. The heat transfer unit 42 is located outside the power element group in a power element arrangement direction, and arranged in a position in which it does not overlap the capacitor 54 when viewed from a plate thickness direction of the capacitor substrate 50. The heat transfer unit 42 comprises a notch C. In the power substrate 20, a circuit element 38A is mounted in a position facing the notch C.SELECTED DRAWING: Figure 9

Description

The present invention relates to a semiconductor device.

As described in Patent Document 1, a semiconductor device that converts DC power into AC power and outputs it includes a power substrate on which a power element is mounted. In addition to the power element, a circuit element such as a chip capacitor is mounted on the power board.

JP-A-2018-38145

In semiconductor devices, miniaturization of power substrates may be required for the purpose of reducing costs, reducing restrictions on arrangement, and the like.
An object of the present invention is to provide a semiconductor device capable of miniaturizing a power substrate.

A semiconductor device that solves the above problems includes a power substrate in which a plurality of power element groups in which a plurality of power elements are arranged are arranged at intervals, and the power substrate is arranged at intervals in the plate thickness direction of the power substrate. A control board on which electronic components for controlling the power element are mounted, a capacitor board on which a plurality of capacitors are mounted, and a power board which are arranged between the power board and the control board. The spacer is provided with a heat sink to which the power substrate is fixed and a spacer for electrically connecting the power substrate and the capacitor substrate. The spacer is a main body arranged between adjacent power element groups and the spacer. A tubular heat transfer unit provided at a position outside the power element group in the direction in which the power elements are lined up and at a position not overlapping the capacitor when viewed from the plate thickness direction of the capacitor substrate is provided. The heat transfer portion is recessed from the first contact surface in contact with the power substrate, the second contact surface in contact with the capacitor substrate, and the second contact surface from the first contact surface. A notch for communicating the inside and outside of the heat transfer portion is provided, and a circuit element is mounted on the power board at a position facing the notch.

Circuit elements are mounted on the power board. By providing the heat transfer portion with the notch portion, the insulation distance from the circuit element arranged at the position facing the notch portion to the spacer can be lengthened as compared with the case where the notch portion is not provided. When the cutout portion is not provided, it is necessary to increase the separation distance between the heat transfer portion and the circuit element in order to secure the insulation distance from the heat transfer portion. That is, the area on which the circuit element can be mounted on the power board is reduced. The power substrate can be miniaturized by providing a notch so that the circuit element can be arranged near the heat transfer portion.

With respect to the semiconductor device, assuming that the direction orthogonal to the axial direction of the heat transfer portion is the thickness direction of the heat transfer portion, the heat transfer portion has a dimension in the thickness direction rather than a dimension in the thickness direction of the notch portion. It may have a long thick portion.

According to this, the strength of the heat transfer portion can be improved by the thick portion.
Regarding the semiconductor device, the thick portion may be provided on the side opposite to the power element group side in the direction in which the power elements are arranged.

At the location where the thick portion is provided, the distance between the circuit element and the heat transfer portion becomes close, and it may be necessary to separate the circuit elements in order to secure the insulation distance. While the circuit elements are arranged on the power element group side in the direction in which the power elements are arranged, it is difficult to arrange the circuit elements on the opposite side of the power element group side in the direction in which the power elements are arranged. By providing a thick portion on the side opposite to the power element group in the direction in which the power elements are lined up, it is less likely that the circuit element needs to be separated from the heat transfer portion.

According to the present invention, the power substrate can be miniaturized.

An exploded perspective view of a semiconductor device. Top view of the power board. The figure which shows a part of a power board enlarged. Perspective view of the spacer. Perspective view of the spacer. The plan view of the spacer which shows the heat transfer part enlarged. Top view of the capacitor board. The perspective view of the semiconductor device in the state where the control board is omitted. 9-9 cross-sectional view of FIG.

Hereinafter, an embodiment of the semiconductor device will be described. The semiconductor device of this embodiment is an inverter mounted on an industrial vehicle such as a forklift. The inverter converts the DC power input from the battery into AC power and outputs it to the three-phase motor. As a result, the three-phase motor is driven. Industrial vehicles run by driving a three-phase motor.

As shown in FIG. 1, the semiconductor device 10 includes a heat sink 11, a power substrate 20, a control substrate 60, and a capacitor substrate 50. The heat sink 11 is made of a metal such as aluminum-based metal or copper. The heat sink 11 includes a plate-shaped mounting portion 12 and fins 13 protruding from one surface of the mounting portion 12 in the plate thickness direction.

The control board 60 is arranged at a distance from the power board 20 in the thickness direction of the power board 20. The capacitor board 50 is arranged between the power board 20 and the control board 60. The thickness direction of the power board 20, the thickness direction of the control board 60, and the thickness direction of the capacitor board 50 are the same. It can be said that the heat sink 11, the power board 20, the capacitor board 50, and the control board 60 are arranged in layers.

As shown in FIGS. 1 and 2, the semiconductor device 10 includes a plurality of power elements 24, two input terminals 25, three output terminals 35, a circuit element 38, and two spacers 40. The power element 24, the input terminal 25, the output terminal 35, the spacer 40, and the circuit element 38 are mounted on the power board 20. The power element 24 of this embodiment is a MOSFET. As the power element 24, for example, an insulated gate bipolar transistor or the like can be used. The plurality of power elements 24 are divided into six power element groups G1, G2, G3, G4, G5, and G6. In the power element groups G1 to G6, the power elements 24 are arranged in a row. Hereinafter, the direction in which the power elements 24 constituting the power element groups G1 to G6 are arranged is defined as the first direction.

The power element groups G1 to G6 are arranged at intervals. More specifically, the power element groups G1 to G6 are arranged in a direction intersecting the first direction among the directions along the surface of the power substrate 20 in the plate thickness direction. Hereinafter, the arrangement direction of each power element group G1 to G6 is referred to as the second direction. Each power element group G1 to G6 constitutes a three-phase upper / lower arm in the inverter.

The power substrate 20 is fixed to the opposite surface of the mounting portion 12 on both sides in the plate thickness direction where the fins 13 are provided. The power substrate 20 of the present embodiment is an insulating metal substrate, and is provided with an insulating layer on a metal base.

As shown in FIGS. 2 and 3, the power substrate 20 includes a plurality of conductor patterns 21, 22, and 23 exposed from the insulating layer. The power element 24 and the circuit element 38 are electrically connected to the conductor patterns 21, 22, and 23. The conductor patterns 21, 22, and 23 are arranged side by side in the second direction at intervals from each other. The conductor patterns 21, 22, and 23 include two conductor patterns 21 connected to the input terminal 25, three conductor patterns 22 connected to the output terminal 35, and two conductor patterns 23 connected to the spacer 40. The circuit element 38 includes various components such as a resistance element, a chip capacitor, a coil, and a diode.

The conductor pattern 21 is arranged so as to sandwich the power element groups G1 to G6. The conductor pattern 22 and the conductor pattern 23 are arranged between adjacent power element groups G1 to G6. The conductor pattern 22 and the conductor pattern 23 are arranged alternately.

The conductor pattern 23 has a first portion 23A extending in the first direction between adjacent power element groups G1 to G6 and a second portion 23B protruding in the first direction from the two adjacent power element groups G1 to G6. And. The second portion 23B is provided outside the power element groups G1 to G6 in the first direction.

The power substrate 20 includes a first through hole forming surface A1 forming the first through hole H1 and a second through hole forming surface A2 forming the second through hole H2. The first through hole H1 and the second through hole H2 penetrate the power substrate 20 in the plate thickness direction. A plurality of first through holes H1 and a plurality of second through holes H2 are provided. The first through hole forming surface A1 is an annular surface surrounding the first through hole H1. The second through hole forming surface A2 is an annular surface surrounding the second through hole H2. The first through hole H1 is provided in a portion of the power substrate 20 in which the conductor patterns 21, 22, and 23 are arranged. Two first through holes H1 are provided in each of the portion where the conductor pattern 21 is arranged and the portion where the conductor pattern 22 is arranged. Two first through holes H1 are provided in the portion where the first portion 23A is arranged, and one is provided in the portion where the second portion 23B is arranged.

As shown in FIG. 1, the two input terminals 25 and the three output terminals 35 are arranged at intervals in the second direction. The two input terminals 25 are arranged so as to sandwich the power element groups G1 to G6. That is, the input terminal 25 is arranged closer to the outer edge of the power substrate 20 than the power element groups G1 to G6 in the second direction. The three output terminals 35 are arranged between the two input terminals 25. The input terminal 25 includes a base portion 26, a columnar portion 27 projecting from the base portion 26, and a pedestal portion 28 projecting from the peripheral surface of the columnar portion 27. The output terminal 35 includes a base portion 36 and a columnar portion 37 protruding from the base portion 36. The input terminal 25 and the output terminal 35 are made of a metal such as aluminum-based metal or copper. The positive electrode of the battery is connected to one of the two input terminals 25, and the negative electrode of the battery is connected to the other of the two input terminals 25. A three-phase motor is connected to the output terminal 35.

The two spacers 40 are arranged at intervals in the second direction. Each spacer 40 is arranged between the output terminals 35. The spacer 40 is made of a metal such as aluminum-based metal or copper.

As shown in FIGS. 4 and 5, the spacer 40 includes a rectangular plate-shaped main body 41 and a tubular heat transfer portion 42 provided at one end of the main body 41 in the longitudinal direction. The main body 41 includes a base 45 and two contact portions 43 projecting from the base 45. The two contact portions 43 project in the plate thickness direction of the main body 41. The two contact portions 43 and the heat transfer portion 42 are arranged side by side in the longitudinal direction of the main body 41. The spacer 40 includes a spacer hole forming surface 46 that forms a spacer hole 44 that penetrates the spacer 40 in the plate thickness direction of the main body 41. The spacer holes 44 are provided in the portion of the main body 41 provided with each contact portion 43 and in the heat transfer portion 42.

The main body 41 includes a contact surface 47A that contacts the power substrate 20 and a contact surface 48A that contacts the capacitor substrate 50. Of both sides of the main body 41 in the plate thickness direction, the opposite surface to which each contact portion 43 is provided is a contact surface 47A that contacts the power substrate 20, and the tip surface of each contact portion 43 is a contact that contacts the capacitor substrate 50. The surface is 48A. The heat transfer unit 42 includes a first contact surface 47B that contacts the power substrate 20 and a second contact surface 48B that contacts the capacitor substrate 50. Each contact surface 47A, 47B, 48A, 48B is smoothed by cutting.

The direction orthogonal to the axial direction of the heat transfer portion 42 is defined as the thickness direction of the heat transfer portion 42. As shown in FIG. 6, the heat transfer portion 42 includes a thick portion 49 whose dimensions in the thickness direction are longer than those of other portions. The thick portion 49 is provided on the edge of the heat transfer portion 42 opposite to the main body 41. The heat transfer portion 42 is recessed from the first contact surface 47B toward the second contact surface 48B, and includes a notch portion C that communicates the inside and outside of the heat transfer portion 42. Notches C are provided at two locations facing the lateral side of the main body 41. The dimension d1 of the notch portion C with respect to the thickness direction of the heat transfer portion 42 is shorter than the dimension d2 of the thick portion 49 with respect to the thickness direction of the heat transfer portion 42. In other words, the thickness direction dimension d2 of the thick portion 49 is longer than the thickness direction dimension d1 of the notch portion C.

As shown in FIGS. 2 and 3, the main body 41 of the spacer 40 overlaps the first portion 23A of the conductor pattern 23. The heat transfer portion 42 of the spacer 40 overlaps the second portion 23B of the conductor pattern 23. As a result, the contact surfaces 47A and 47B are electrically connected to the conductor pattern 23 of the power substrate 20. The spacer 40 is arranged so that the notch C faces in the second direction. Since the two notches C are arranged so as to face each other, the notches C are arranged so as to open on both sides in the second direction. Some of the circuit elements 38A among the plurality of circuit elements 38 arranged on the power board 20 face the notch C.

The main body 41 of the spacer 40 is arranged between the power element groups G1 to G6. The heat transfer portion 42 of the spacer 40 is arranged outside the power element groups G1 to G6 in the first direction, which is the direction in which the power elements 24 are arranged.

As shown in FIGS. 7 and 8, the semiconductor device 10 includes a plurality of capacitors 54 mounted on the capacitor substrate 50, and a resin portion 59. In the capacitor substrate 50, a plurality of capacitors 54 are arranged along one of the edges 55 and 56 in the first direction. The capacitors 54 are arranged closer to the edge 55 than the center C1 of the capacitor substrate 50 in the first direction. When the capacitor board 50 is divided into two by the center C1 in the first direction of the capacitor board 50, the capacitor 54 is arranged in one area and the capacitor 54 is not arranged in the other area. The capacitor substrate 50 includes a non-arranged region 57 in which the capacitor 54 is not provided in a part of the portion along the edge 55. The capacitor 54 has a columnar shape, and is arranged so that the axial direction and the thickness direction of the capacitor substrate 50 coincide with each other. It can be said that the capacitor 54 is erected on the capacitor substrate 50.

As shown in FIGS. 1 and 7, the capacitor substrate 50 forms a resist 51, a pattern 52 exposed from the resist 51, an output hole forming surface A3 forming the output hole 53, and a third through hole H3. 3 A through-hole forming surface A4 is provided. The pattern 52 is provided along the capacitor 54. The columnar portion 37 of the output terminal 35 is inserted through the output hole 53. The third through holes H3 are provided at a plurality of locations including the non-arranged region 57. The same number of third through holes H3 as the first through holes H1 are provided. The distance between the third through holes H3 is the same as the distance between the first through holes H1. The third through hole H3 and the first through hole H1 are arranged so as to face each other in the plate thickness direction of the capacitor substrate 50. The resin portion 59 is provided in each pattern 52. The resin portion 59 is a resin potted so as to come into contact with both the pattern 52 and the capacitor 54. As the resin portion 59, for example, a resin containing a thermally conductive filler is used.

As shown in FIGS. 1, 8 and 9, the capacitor substrate 50 is arranged so as to overlap the base 26 of the input terminal 25, the base 36 of the output terminal 35, and the spacer 40. The capacitor substrate 50 is arranged so that the non-arranged region 57 and the heat transfer portion 42 of the spacer 40 face each other. It can be said that the heat transfer portion 42 is arranged at a position that does not overlap with the capacitor 54 when viewed from the thickness direction of the capacitor substrate 50. The contact surfaces 48A and 48B of the spacer 40 are in contact with the capacitor substrate 50. The capacitor substrate 50 and the power substrate 20 are electrically connected to each other via the base 26 of the input terminal 25, the base 36 of the output terminal 35, and the spacer 40.

As shown in FIG. 1, the control board 60 includes an output hole forming surface A5 that forms an output hole 61 penetrating in the plate thickness direction. The columnar portion 37 of the output terminal 35 is inserted through the output hole 61. The control board 60 is fixed by a board support member (not shown) while maintaining a distance from the capacitor board 50.

The semiconductor device 10 includes a plurality of electronic components 63 mounted on the control board 60. The electronic component 63 constitutes a control circuit that controls each of the power element groups G1 to G6. Power conversion is performed by controlling each power element group G1 to G6 by the control circuit.

The semiconductor device 10 includes a plurality of screws S1 for fixing the power substrate 20 and the capacitor substrate 50 to the heat sink 11, and an insulating insulator I.
The plurality of screws S1 are fastened to the mounting portion 12 of the heat sink 11 by inserting the third through hole H3 of the capacitor substrate 50 and the first through hole H1 of the power substrate 20 together with the insulator I. As a result, the screw S1 fastens the power board 20 and the capacitor board 50 together. Further, some of the plurality of screws S1 have the spacer hole 44 of the spacer 40 inserted together with the third through hole H3 and the first through hole H1. As a result, the spacer 40 is mounted on the power board 20.

Next, the operation of the semiconductor device 10 will be described.
When the semiconductor device 10 is driven, a member through which an electric current flows, such as a power element 24 and an electronic component 63, generates heat. The heat generated by the power element 24 and the power substrate 20 is conducted from the power substrate 20 to the heat sink 11.

The heat generated by the capacitor 54 and the capacitor board 50 is conducted to the power board 20 via the input terminal 25, the output terminal 35, and the spacer 40. The heat conducted on the power substrate 20 is conducted on the heat sink 11. The heat of the capacitor substrate 50 can be conducted to the heat sink 11 via the power substrate 20. Since the spacer 40 of the present embodiment includes the main body 41 and the heat transfer portion 42, heat is conducted from the capacitor substrate 50 to the power substrate 20 using both the main body 41 and the heat transfer portion 42 as heat transfer paths. If the spacer 40 does not include the heat transfer portion 42, the heat transfer path for conducting the heat of the capacitor substrate 50 to the power substrate 20 is only the main body 41. When the heat transfer path of the spacer 40 is only the main body 41, the contact area of the spacer 40 with the capacitor substrate 50 and the power substrate 20 is small, and the heat capacity of the spacer 40 is also small. Therefore, the amount of heat conducted to the power substrate 20 via the spacer 40 is small.

In the semiconductor device 10 of the embodiment, the capacitors 54 are integrated on the edge 55 side of the capacitor substrate 50. When the capacitor 54 is arranged in this way, the load is concentrated on the edge 55 side of the capacitor board 50 due to the weight of the capacitor 54, and the position of the center of gravity is closer to the edge 55 side than the center C1 of the capacitor board 50. Then, the edge 55 side of the capacitor substrate 50 is easily bent due to vibration or shock, and the capacitor 54 is easily dropped off.

By arranging the heat transfer portion 42 between the power substrate 20 and the edge 55 side of the capacitor substrate 50 as in the present embodiment, the capacitor substrate 50 is supported by the heat transfer portion 42, and the capacitor substrate 50 is supported. Bending can be suppressed.

Further, by providing the resin portion 59, the heat generated by the capacitor 54 is transferred to the pattern 52 via the resin portion 59. By providing the resin portion 59, the heat transfer path from the capacitor 54 to the capacitor substrate 50 can be increased, and the heat dissipation of the capacitor 54 can be improved. Further, the base of the capacitor 54 is reinforced by the resin portion 59, so that the capacitor 54 is further suppressed from falling off.

As described above, by providing the heat transfer portion 42, effects such as improvement of heat dissipation of the capacitor substrate 50 by increasing the heat transfer path and suppression of bending of the capacitor substrate 50 can be obtained. On the other hand, if the heat transfer unit 42 is provided, it is necessary to arrange the circuit element 38 while ensuring an insulation distance from the heat transfer unit 42 when mounting the circuit element 38. Therefore, when the heat transfer unit 42 is provided, the area on which the circuit element 38 can be mounted on the power board 20 is reduced, which causes the power board 20 to become large.

In the present embodiment, by providing the heat transfer portion 42 with the notch portion C, the insulation distance from the circuit element 38A arranged at the position facing the notch portion C to the spacer 40 can be increased as compared with the case where the notch portion C is not provided. Can be lengthened. The circuit element 38A can be arranged closer to the heat transfer portion 42 as compared with the case where the notch portion C is not provided.

The effect of this embodiment will be described.
(1) A notch C is provided in the heat transfer portion 42 of the spacer, and the circuit element 38A is arranged so as to face the notch C. The circuit element 38A can be arranged closer to the heat transfer portion 42 as compared with the case where the notch portion C is not provided. By increasing the area on which the circuit element 38 can be mounted as compared with the case where the notch portion C is not provided, it is possible to suppress the increase in size of the power substrate 20 due to the provision of the heat transfer portion 42.

(2) The heat transfer section 42 includes a thick section 49. The strength of the heat transfer portion 42 can be improved by the thick portion 49. By providing the notch portion C, the strength of the heat transfer portion 42 is reduced. By providing the thick portion 49 so as to compensate for the strength reduced by providing the notch portion C, it is possible to prevent the heat transfer portion 42 from breaking due to stress or the like when the screw S1 is fastened. Further, by providing the thick portion 49, the areas of the first contact surface 47B and the second contact surface 48B can be increased, and the heat capacity of the heat transfer portion 42 is increased. Therefore, heat can be easily conducted from the capacitor board 50 to the power board 20.

(3) The thick portion 49 is provided on the side opposite to the power element groups G1 to G6 in the first direction. At the location where the thick portion 49 is provided, the distance between the circuit element 38 and the heat transfer portion 42 becomes close, and it may be necessary to separate the circuit element 38 in order to secure the insulation distance. In the first direction, the circuit element 38 is arranged on the power element group G1 to G6 side, while in the first direction, the circuit element 38 is difficult to be arranged on the opposite side of the power element group G1 to G6 side. By providing the thick portion 49 in the first direction on the side opposite to the power element groups G1 to G6, it is less likely that the circuit element 38 needs to be separated from the heat transfer portion 42.

The embodiment may be changed as follows.
The thick portion 49 may be provided at any position in the first direction, such as on the power element groups G1 to G6 side. In this case, it is preferable to provide the thick portion 49 at a position where the insulation distance from the circuit element 38 mounted on the power board 20 can be secured.

○ A thick portion may be provided on the entire heat transfer portion 42. In this case, the thickness direction of the end portion on the capacitor board 50 side of both ends in the axial direction of the heat transfer portion 42 is the thickness of the end portion on the power substrate 20 side of both ends in the axial direction of the heat transfer portion 42. Make it longer than the directional dimension. That is, the dimension in the thickness direction of the heat transfer portion 42 is shortened on the first contact surface 47B side where it is necessary to secure the insulation distance from the circuit element 38, and the thickness direction of the heat transfer portion 42 on the second contact surface 48B side. Increase the dimensions.

○ The heat transfer portion 42 does not have to include the thick portion 49.
○ The number and position of the notches C provided in the spacer 40 may be changed as appropriate. The number and position of the notch portions C can be appropriately changed depending on the arrangement position of the circuit element 38 and the like.

○ The spacer 40 may be fixed by a screw other than the screw S1. For example, the spacer 40 may be fixed to the power substrate 20 and the capacitor substrate 50 by a bonding material such as solder.

○ The capacitor 54 does not have to be concentrated on the edge 55 side of the center C1. That is, the capacitors 54 may be arranged on both sides of the center C1 of the capacitor substrate 50. In this case, the number of capacitors 54 arranged on one side of the center C1 and the number of capacitors 54 arranged on the other side may be the same or different. When the number of capacitors 54 is different, the heat transfer portion 42 may be provided in the direction in which the position of the center of gravity is biased in the first direction. That is, the heat transfer portion 42 may be provided at a position where the capacitor substrate 50 is easily bent.

○ The heat transfer portions 42 of the spacer 40 may be provided at both ends of the main body 41 in the longitudinal direction. In this case, each heat transfer unit 42 is arranged outside the power element groups G1 to G6 in the first direction.

○ The heat sink 11 may be a heat radiating plate or the like that does not have fins 13. The heat sink may be cooled by a gaseous refrigerant or may be cooled by a liquid refrigerant.

○ The semiconductor device 10 does not have to include the resin portion 59. In this case, the pattern 52 does not have to be exposed from the resist 51.
○ The semiconductor device 10 may be other than an inverter. For example, the semiconductor device 10 may be a power conversion device other than an inverter, such as a converter. Further, the power element 24 may be, for example, a semiconductor device 10 using a diode or the like.

○ The semiconductor device 10 does not have to be mounted on an industrial vehicle.

C ... Notch, G1 to G6 ... Power element group, 10 ... Semiconductor device, 11 ... Heat sink, 20 ... Power board, 24 ... Power element, 38, 38A ... Circuit element, 40 ... Spacer, 41 ... Main body, 42 ... Transmission Heat part, 47B ... 1st contact surface, 48B ... 2nd contact surface, 49 ... Thick part, 50 ... Capacitor board, 54 ... Capacitor, 60 ... Control board, 63 ... Electronic component.

Claims (3)

A power board in which a plurality of power element groups in which a plurality of power elements are arranged are arranged at intervals, and
A control board which is arranged at a distance from the power board in the thickness direction of the power board and on which electronic components for controlling the power element are mounted.
A capacitor board arranged between the power board and the control board and on which a plurality of capacitors are mounted,
With the heat sink to which the power board is fixed,
A spacer that electrically connects the power board and the capacitor board is provided.
The spacer is
The main body arranged between the adjacent power element groups and
A tubular heat transfer portion provided at a position outside the power element group in the direction in which the power elements are lined up and at a position not overlapping the capacitor when viewed from the thickness direction of the capacitor substrate. Prepare,
The heat transfer unit
The first contact surface in contact with the power substrate and
The second contact surface in contact with the capacitor substrate and
It is provided with a notch portion that is recessed from the first contact surface toward the second contact surface and communicates the inside and outside of the heat transfer portion.
A semiconductor device in which a circuit element is mounted on the power board at a position facing the notch. Assuming that the direction orthogonal to the axial direction of the heat transfer portion is the thickness direction of the heat transfer portion,
The semiconductor device according to claim 1, wherein the heat transfer portion includes a thick portion having a thickness direction longer than the thickness direction dimension of the notch portion. The semiconductor device according to claim 2, wherein the thick portion is provided on the side opposite to the power element group side in the direction in which the power elements are arranged.