Semiconductor device and power conversion device

Abstract

To solve the problem of insulation property by an insulation sheet.SOLUTION: A semiconductor device includes a plurality of semiconductor elements, a conductor plate to which the plurality of semiconductor elements are joined, an insulation sheet bonded to a surface opposite to the side of the plurality of semiconductor elements in the conductor plate, and a resin member for sealing the plurality of semiconductor elements, the insulation sheet and the conductor plate, wherein the conductor plate has a plurality of element bonding regions where each of the plurality of semiconductor elements are bonded to each other, and a connection region provided between the plurality of element bonding regions, the surface on the side of the insulation sheet in the element bonding region of the conductor plate projects from the surface on the side of the insulation sheet of the connection region and is bonded to the insulation sheet, and a space between the surface on the side of the insulation sheet in the connection region and the insulation sheet is filled with the resin member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a semiconductor device and a power conversion device. [Background technology]

[0002] Power conversion devices that use switching of semiconductor elements have high conversion efficiency and are therefore widely used in consumer, in-vehicle, railway, substation equipment, etc. This power conversion device is composed of a semiconductor device. The semiconductor device includes a semiconductor element, a conductor plate to which the semiconductor element is bonded, and an insulating sheet adhered to the surface of the conductor plate opposite the semiconductor element side, and these are sealed with a resin member. In particular, for in-vehicle applications, high reliability is required of the semiconductor device.

[0003] Patent Document 1 discloses an electric circuit body in which a sheet-like member (insulating sheet) having a resin insulating layer, a conductive plate, and a semiconductor element are covered with a sealing resin by transfer molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-048255 Summary of the Invention [Problem to be solved by the invention]

[0005] The semiconductor device described in Patent Document 1 has a problem with the insulation provided by the insulating sheet. [Means for solving the problem]

[0006] A semiconductor device according to the present invention comprises a plurality of semiconductor elements, a conductor plate to which the plurality of semiconductor elements are bonded, an insulating sheet adhered to the side of the conductor plate opposite the plurality of semiconductor elements, and a resin member that seals the plurality of semiconductor elements, the insulating sheet, and the conductor plate, wherein the conductor plate has a plurality of element bonding regions to which each of the plurality of semiconductor elements is bonded, and a connecting region provided between the plurality of element bonding regions, and the insulating sheet side surface of the conductor plate in the element bonding region protrudes beyond the insulating sheet side surface of the connecting region and is bonded to the insulating sheet, and the resin member is filled between the insulating sheet side surface of the conductor plate in the connecting region and the insulating sheet. Effect of the Invention

[0007] According to the present invention, it is possible to provide a highly reliable semiconductor device in which the insulating properties of the insulating sheet are improved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view of one embodiment of an electrical circuit body. [Diagram 2] FIG. 2 is a cross-sectional view of the electric circuit body taken along line XX. [Diagram 3] 4 is a cross-sectional view of the electric circuit body taken along line YY. FIG. [Figure 4] FIG. 1 is a cross-sectional perspective view of a semiconductor device. [Diagram 5] FIG. 2 is a semi-transparent plan view of the semiconductor device. [Figure 6] FIG. 1 is a circuit diagram of a semiconductor device. [Figure 7] 1(a) to 1(d) are cross-sectional views illustrating a manufacturing process of a semiconductor device. [Figure 8] 3(a) to 3(c) are cross-sectional views illustrating the principle of improved insulation. [Figure 9] 1A to 1C are cross-sectional views showing a schematic diagram of the principle by which insulation is improved during the injection of a resin member. [Figure 10] 1(a) to 1(c) are cross-sectional views showing schematic diagrams of comparative examples. [Figure 11]11A and 11B are cross-sectional views each showing a comparative example during an injection process of a resin member. [Figure 12] 13A and 13B are a semi-transparent plan view and a cross-sectional view of a semiconductor device according to a modified example. [Figure 13] FIG. 11 is a diagram showing the relationship between the amount of shrinkage of a resin member and temperature. [Figure 14] 1 is a circuit diagram of a power conversion device using a semiconductor device. [Figure 15] FIG. 2 is an external perspective view of the power conversion device. [Figure 16] 1 is a cross-sectional perspective view of the power conversion device taken along line XV-XV. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] FIG. 1 is a plan view of an electrical circuit body 400. FIG. The electric circuit body 400 comprises three semiconductor devices 300 and a cooling member 340 for cooling the semiconductor devices 300 .

[0012] The semiconductor device 300, the details of which will be described later, comprises a semiconductor element, a conductor plate to which the semiconductor element is bonded, and an insulating sheet adhered to the surface of the conductor plate opposite the semiconductor element side, and these are sealed with a resin member 360. The semiconductor device 300 converts DC power to AC power and vice versa using a semiconductor element. The semiconductor device 300 generates heat when electricity is passed through the semiconductor element, and this heat is cooled by a cooling member 340. A coolant flows inside the cooling member 340, and the coolant used is an antifreeze liquid such as water or water mixed with ethylene glycol.

[0013] The semiconductor device 300 includes power terminals through which a large current flows, such as a positive terminal 315B and a negative terminal 319B connected to a capacitor module 500 (see FIG. 14) of a DC circuit, and an AC terminal 320B connected to motor generators 192, 194 (see FIG. 14) of an AC circuit. The semiconductor device 300 also includes a lower arm gate terminal 325L, a mirror emitter signal terminal 325M, and a Kelvin emitter signal terminal 325K corresponding to the semiconductor elements of the lower arm. The semiconductor device 300 also includes signal terminals used to control the semiconductor device, such as an upper arm gate terminal 325U, a mirror emitter signal terminal 325M, and a Kelvin emitter signal terminal 325K corresponding to the semiconductor elements of the upper arm.

[0014] Fig. 2 is a cross-sectional view of the electric circuit body 400 taken along line XX in Fig. 1. Fig. 3 is a cross-sectional view of the electric circuit body 400 taken along line YY in Fig. 1. The first power semiconductor elements 155 and 156 forming the upper arm circuit include an active element 155 and a diode 156. The active element 155 may be made of Si, SiC, GaN, GaO, C, or the like. When a body diode of the active element 155 is used, a separate diode may be omitted. The collector sides of the first power semiconductor elements 155 and 156 are joined to a second conductor plate 431. For this joining, solder or sintered metal may be used. The first conductor plate 430 is joined to the emitter sides of the first power semiconductor elements 155 and 156. The second power semiconductor elements 157 and 158 forming the lower arm circuit include an active element 157 and a diode 158. The collector sides of the second power semiconductor elements 157 and 158 are joined to a fourth conductor plate 433. The third conductor plate 432 is joined to the emitter sides of the second power semiconductor elements 157 and 158.

[0015] The conductive plates 430, 431, 432, and 433 are not particularly limited as long as they are made of a material having high electrical conductivity and thermal conductivity, but are preferably made of a copper- or aluminum-based material. These may be used alone, or may be plated with Ni, Ag, or the like to improve bonding with solder or sintered metal.

[0016] The conductor plates 430, 431, 432, and 433, in addition to carrying electric current, also serve as heat transfer members that transfer heat generated by the power semiconductor elements 155, 156, 157, and 158 to the cooling member 340. Since the conductor plates 430, 431, 432, and 433 and the cooling member 340 have different electric potentials, insulating sheets 440 and 441 are placed between them. A heat conductive member 453 is placed between the insulating sheets 440 and 441 and the cooling member 340 to reduce contact thermal resistance. The power semiconductor elements 155, 156, 157, and 158, the conductor plates 430, 431, 432, and 433, and the insulating sheets 440 and 441 are sealed with the resin member 360 by transfer molding.

[0017] The insulating sheet 440 will be described as having a laminated structure of a resin insulating layer 442 and a metal foil 444, and the insulating sheet 441 will be described as having a laminated structure of a resin insulating layer 443 and a metal foil 444, but the insulating sheets 440 and 441 may each be a single resin insulating layer 442 or 443. When the insulating sheets 440 and 441 are a laminated structure of the resin insulating layers 442 and 443 and the metal foil 444, the metal foil 444 is disposed on the side in contact with the heat conductive member 453. The resin insulating layers 442 and 443 of the insulating sheets 440 and 441 are not particularly limited as long as they have adhesive properties with the conductive plates 430, 431, 432, and 433, but the resin insulating layers 442 and 443 of an epoxy resin system in which a powdered inorganic filler is dispersed are preferable. This is because they have a good balance between adhesiveness and heat dissipation. In the transfer molding process, when the insulating sheets 440 and 441 are mounted on a metal mold, metal foil 444 is provided on the contact surface between the insulating sheets 440 and 441 and the metal mold to prevent adhesion to the metal mold. If a release sheet is used to prevent adhesion to the metal mold, a peeling process is required after transfer molding because the release sheet has poor thermal conductivity. However, in the case of metal foil 444, by selecting a copper-based or aluminum-based metal with high thermal conductivity, the peeling process after transfer molding is not required. By performing transfer molding including the insulating sheets 440 and 441, the ends of the insulating sheets 440 and 441 are covered with the resin member 360, which has the effect of improving reliability.

[0018] As shown in FIG. 2, the conductive plates 430, 431, 432, 433 have element bonding regions 462 which bond the power semiconductor elements 155, 156, 157, 158, and connecting regions 463 which connect the element bonding regions 462, and also have a protrusion 461 directly above the element bonding region 462.

[0019] The protruding portion 461 is bonded to the insulating sheet 440 at the adhesion region 464. In addition, the connecting region 463 forms a resin-filled space 460 between the insulating sheet 440 and the first conductive plate 430. The resin-filled space 460 is filled with the resin member 360 in a transfer molding process described later, and is connected to the resin member 360 that seals the power semiconductor elements 155, 156, 157, and 158, the insulating sheet 440, and the conductive plates 430, 431, 432, and 433. Since the resin insulating layer 442 of the insulating sheet 440 and the resin member 360 are cured simultaneously in the transfer molding process, the resin components of the resin insulating layer 442 and the resin member 360 penetrate each other, and the resin insulating layer 442 and the resin member 360 have higher adhesion than when the resin insulating layer 442 and the resin member 360 are bonded after curing. It is desirable that the resin-filled space 460 has a thickness of 300 μm or more so that the resin member 360 can be sufficiently filled. From the viewpoint of insulation, it is preferable that the thickness of the insulating sheet 440 is thicker than that of the resin insulating layer 442 .

[0020] The conductor plates 430, 431, 432, and 433 are desirably made of a material having high electrical conductivity and high thermal conductivity, and may be made of a metal material such as copper or aluminum, or a composite material of a metal material and a high thermal conductivity material such as diamond, carbon, or ceramic. The connection region 463 of the conductor plates 430, 431, 432, and 433 is made by making a depression by press processing, cutting by machining or laser processing, connecting low-rigidity members, or the like.

[0021] The cooling member 340 is preferably made of aluminum, which has high thermal conductivity and is lightweight, and is manufactured by extrusion molding, forging, brazing, or the like. Although there are no particular limitations on the material for heat conductive member 453 as long as it is a material with high thermal conductivity, it is preferable to use a highly heat conductive material such as a metal, ceramic, or carbon-based material in combination with a resin material. This is because the resin material fills in the gaps between the highly heat conductive materials, between the highly heat conductive material and cooling member 340, and between the highly heat conductive member and insulating sheets 440 and 441, thereby reducing contact thermal resistance.

[0022] FIG. 4 is a cross-sectional perspective view of the semiconductor device 300. As shown in FIG. Conductive plate 430 has protruding portion 461 bonded to insulating sheet 440 at contact region 464. Resin filling space 460 is formed between insulating sheet 440 and first conductive plate 430, and resin filling space 460 is filled with resin member 360.

[0023] Fig. 5 is a semi-transparent plan view of the semiconductor device 300. Fig. 6 is a circuit diagram of the semiconductor device 300. As shown in FIG. 5 and FIG. 6, the positive terminal 315B is output from the collector side of the upper arm circuit and is connected to the positive side of a battery or a capacitor. The upper arm gate terminal 325U is output from the gate of the active element 155 of the upper arm circuit, and the upper arm Kelvin emitter signal terminal 325K is output from the emitter sense of the active element 155 of the upper arm circuit. The negative terminal 319B is output from the emitter side of the lower arm circuit and is connected to the negative side of a battery or a capacitor, or GND. The lower arm gate terminal 325L is output from the gate of the active element 157 of the lower arm circuit, and the lower arm Kelvin emitter signal terminal 325K is output from the emitter sense of the active element 157 of the lower arm circuit. The AC side terminal 320B is output from the collector side of the lower arm circuit and is connected to a motor. When the neutral point is grounded, the lower arm circuit is connected to the negative side of a capacitor instead of GND.

[0024] Moreover, conductor plates (upper arm circuit emitter side) 430 and conductor plates (upper arm circuit collector side) 431 are arranged above and below active element 155 and diode 156 of the power semiconductor element (upper arm circuit). Conductor plates (lower arm circuit emitter side) 432 and conductor plates (lower arm circuit collector side) 433 are arranged above and below active element 157 and diode 158 of the power semiconductor element (lower arm circuit).

[0025] The semiconductor device 300 of this embodiment has a 2-in-1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into one module. Alternatively, a structure in which a plurality of upper arm circuits and lower arm circuits are integrated into one module may be used. In this case, the number of output terminals from the semiconductor device 300 can be reduced, resulting in a smaller size.

[0026] 7(a) to 7(d) are cross-sectional views for explaining the manufacturing process of the semiconductor device 300. As in FIG. 2, they are cross-sectional views taken along the line XX for one module.

[0027] 7(a) shows a temporary attachment process. The collector sides of the power semiconductor elements 155, 156 are connected to the conductor plates 430, 431, and the gate electrodes of the power semiconductor elements 155, 156 are connected by wire bonding. Furthermore, the emitter sides of the power semiconductor elements 155, 156 are connected to the conductor plates 430, 431 to fabricate the circuit body 310. Thereafter, the insulating sheets 440, 441 are temporarily attached to the conductor plates 430, 431. Temporary attachment refers to temporarily attaching the insulating sheets 440, 441 by using their adhesive strength under conditions that leave room for the insulating sheets 440, 441 to harden and adhere in the subsequent transfer molding process.

[0028] 7(b) to 7(d) show the transfer molding process. A transfer molding device 601 has a spring 602 in a mold 603. This spring 602 allows a predetermined load to be applied by the force of the spring 602 without applying excessive pressure to the power semiconductor elements 155 and 156 even if the height of the circuit body 310 varies. The transfer molding device 601 also has a vacuum degassing mechanism (not shown). By performing vacuum degassing, even if voids are involved in the resin member 360 or the like, the voids can be compressed to a small size, improving insulation. Furthermore, by covering the circuit body 310 with a release film (not shown), it is possible to prevent resin burrs from entering the spring drive unit or the like.

[0029] As shown in FIG. 7(b), the circuit body 310 to which the insulating sheets 440 and 441 are temporarily attached is set in a mold 603 that has been heated to a constant temperature of 175° C. in advance. Next, as shown in FIG. 7(c), the upper and lower molds 603 are clamped. At this time, the insulating sheets 440 and 441 and the conductor plates 430 and 431 are pressed by the spring 602 and are in close contact with each other. The conductor plate 431 located on the collector side is pressed toward the lower mold 603 when the terminal portion on the outer periphery of the conductor plate 431 is clamped by the mold, and is pressed against the insulating sheet 441 with a stronger force than the conductor plate 430 located on the emitter side because it is added to the force of the spring 602. The conductor plate 430 located on the emitter side is pressed against the insulating sheet 440 by the force of the spring 602, but the force of the spring 602 is also applied to the power semiconductor elements 155 and 156. For this reason, if strong pressure is applied to improve the insulation, excessive pressure is applied to the power semiconductor elements 155, 156. In this embodiment, the insulation provided by the insulating sheets 440, 441 is improved without applying excessive pressure to the power semiconductor elements 155, 156 by providing a resin-filled space 460, which will be described in detail later.

[0030] 7(d), resin member 360 is injected into mold 603. Then, resin-sealed semiconductor device 300 is removed from transfer molding device 601 and post-cured at 175° C. for 2 hours or more. Next, cooling member 340 is joined via thermal conductive member 452 to prepare electric circuit body 400.

[0031] Figures 8(a) to 8(c) are cross-sectional views that typically show the principle of how insulation is improved in the transfer molding process shown in Figures 7(b) to 7(d). In Figures 8(a) to 8(c), for ease of understanding, the thickness of insulating sheet 440 is enlarged relative to the thickness of conductive plate 430, and insulating sheet 440 and conductive plate 430 are partially shown.

[0032] In the resin insulating layer 442 of the insulating sheet 440, a large amount of filler (not shown) is filled in the resin component such as epoxy resin for high thermal conductivity. Therefore, as shown in FIG. 8(a), there may be a minute void 465 near the interface between the resin component and the filler. Such a void 465 causes a decrease in the insulation of the insulating sheet 440. As shown in FIG. 8(b), when the transfer molding device 601 clamps the insulating sheet 440 and the force P of the spring 602 acts, the load spreads from the element bonding region 462 at an angle of about 45 degrees to the thickness direction of the conductive plate 430. Outside this 45-degree line M, the load due to the force P of the spring 602 is greatly attenuated. By placing the contact region 464 between the conductive plate 430 and the insulating sheet 440 inside the line where the load spreads from the element bonding region 462 at an angle of about 45 degrees to the thickness of the conductive plate 430, the load due to the force P of the spring 602 can be efficiently applied to the contact region 464. A load is also efficiently applied to the inside of the same 45-degree line M on resin insulation layer 442 in contact with adhesion region 464. This load compresses voids 465 in resin insulation layer 442 of insulation sheet 440, reducing the size of voids 465 and improving the insulation of insulation sheet 440. Outside this 45-degree line M, voids 465 in resin insulation layer 442 remain uncompressed, but voids 465 directly above adhesion region 464, where the electric field strength is high, are compressed, improving the insulation of insulation sheet 440.

[0033] Also, as shown in FIG. 8(c), by making the thickness L2 of the resin filled space 460 equal to or greater than the thickness L1 of the resin insulating layer 442, the resin member 360 filled in the resin filled space 460 acts as an insulating layer, and insulation can be ensured even if the voids 465 remain in the resin insulating layer 442 facing the resin filled space 460 without being compressed. Note that in FIG. 8(c), the thickness of the insulating sheet 440 is illustrated enlarged relative to the thickness of the conductive plate 430, so that the thickness L2 of the resin filled space 460 is illustrated as being thinner than the thickness L1 of the resin insulating layer 442. However, in reality, as described above, the thickness L2 of the resin filled space 460 is equal to or greater than the thickness L1 of the resin insulating layer 442. Also, when the insulating sheet 440 is composed of the resin insulating layer 442 alone, the thickness L2 of the resin filled space 460 is equal to or greater than the thickness L1 of the insulating sheet 440.

[0034] Fig. 9 is a cross-sectional view showing the principle of the improvement in insulation during the injection of the resin member in the transfer molding process shown in Fig. 7(d). As in Figs. 8(a) to 8(c), for ease of understanding, the thickness of the insulating sheet 440 is enlarged compared to the thickness of the conductive plate 430, and the insulating sheet 440 and the conductive plate 430 are partially shown.

[0035] When resin member 360 is injected in the transfer molding process, molding pressure acts in all directions as hydrostatic pressure while resin member 360 is in a liquid state. Of these hydrostatic pressures, the force acting upward in FIG. 9 is indicated by a black arrow as molding pressure P1. In FIG. 9, the force acting downward is indicated by a white arrow as molding pressure P2. In resin filling space 460, molding pressure P1 acts in a direction that compresses insulating sheet 440. Focusing on conductive plate 430, molding pressure P1 applied upward from below to conductive plate 430 is cancelled out by molding pressure P2 by resin member 360 that has entered resin filling space 460, thereby reducing the force pushing up conductive plate 430. When a force in the peeling direction is applied to the element bonding region 462 that bonds the power semiconductor elements 155 and 156, there is a concern that the bonding material such as solder that bonds the element bonding region 462 may peel off, so it is necessary to strengthen the force P of the spring 602 to face the molding pressure P1 that is applied upward from the bottom to the conductor plate 430. In this way, by providing the resin filling space 460, the force that pushes the conductor plate 430 upward by the molding pressure P1 is reduced, so there is an effect that the force P of the spring 602 can be reduced. By reducing the force P of the spring 602, there is an effect that the cost of the transfer molding device 601 is reduced by simplifying the mold structure, and the cost of the spring 602 is reduced. In addition, since the power semiconductor elements 155 and 156 are not excessively pressurized, there is an effect that the yield of the semiconductor device 300 is excellent.

[0036] 10(a) to 10(c) are cross-sectional views that show a comparative example in the transfer molding process. In this comparative example, a resin filling space 460 is not provided, and an example is shown in which this embodiment is not applied. As in FIGS. 8(a) to 8(c), for ease of understanding, the thickness of the insulating sheet 440 is enlarged compared to the thickness of the conductive plate 430, and the insulating sheet 440 and the conductive plate 430 are partially shown.

[0037] In the insulating sheet 440, a resin component such as epoxy resin is filled with a large amount of filler (not shown) in order to increase thermal conductivity. Therefore, as shown in FIG. 10(a), minute voids 465 may exist near the interface between the resin component and the filler. Such voids 465 cause a decrease in insulation. When the sheet is clamped by the transfer molding device 601 and the force P of the spring 602 acts, as shown in FIG. 10(b), the load spreads from the element bonding region 462 at an angle of about 45 degrees to the plate thickness direction of the conductor plate 430. Outside this 45-degree line M, the load due to the force P of the spring 602 is greatly attenuated. A load is also applied to the resin insulating layer 442 of the insulating sheet 440 on the inside of the 45-degree line M. This load compresses the voids 465 in the resin insulating layer 442.

[0038] On the other hand, outside the 45-degree line M, the voids 465 in the resin insulating layer 442 remain uncompressed. In this comparative example, since the resin filling space 460 is not provided, the adhesion region 464 is also located outside the 45-degree line M from the element bonding region 462. Therefore, there is a region where the voids are not compressed directly above the adhesion region 464 where the electric field strength is high, and the insulation is reduced. Also, as shown in FIG. 10(c), since the resin filling space 460 is not provided, only the thickness L1 of the resin insulating layer 442 functions as an insulating layer. Therefore, if the thickness L1 of the resin insulating layer 442 is increased to improve the insulation, the thermal resistance from the conductor plate 430 through the insulating sheet 440 to the cooling member 340 increases, and the heat dissipation of the semiconductor device 300 is reduced.

[0039] Fig. 11 is a cross-sectional view showing the principle of insulation in a comparative example during the injection of the resin member in the transfer molding process shown in Fig. 7(d). This comparative example shows an example in which the resin filling space 460 is not provided and the present embodiment is not applied. As in Figs. 8(a) to 8(c), for ease of understanding, the thickness of the insulating sheet 440 is enlarged compared to the thickness of the conductive plate 430, and the insulating sheet 440 and the conductive plate 430 are partially shown.

[0040] When the resin member 360 is injected in the transfer molding process, while the resin member 360 is in a liquid state, molding pressure acts in all directions as hydrostatic pressure. Of these hydrostatic pressures, the force acting upward in FIG. 11 is indicated by a black arrow as molding pressure P1. Focusing on the conductor plate 430, the conductor plate 430 is pushed up by the molding pressure P1. If a force in the peeling direction is applied to the element bonding region 462 that bonds the power semiconductor elements 155 and 156, there is a concern that the bonding material such as solder that bonds the element bonding region 462 may peel off, so it is necessary to increase the force P of the spring 602 to counter this molding pressure P1. If the force P of the spring 602 is increased, the cost of the transfer molding device 601 will increase, and the power semiconductor elements 155 and 156 will be excessively pressurized, which will deteriorate the yield of the semiconductor device 300. For this reason, it is necessary to keep molding pressure P1 low. However, a reduction in molding pressure P1 leads to insufficient compression of voids 465, and as a result, the insulating properties of insulating sheet 440 deteriorates.

[0041] 12A is a semi-transparent plan view of a semiconductor device 300' according to a modified example, which corresponds to the semi-transparent plan view of the semiconductor device 300 shown in FIG. As shown in FIG. 12(a), the power semiconductor elements 155 forming the upper arm circuit are arranged in two rows, five in each row, on the second conductor plate 431. Similarly, the power semiconductor elements 157 forming the lower arm circuit are arranged in two rows, five in each row, on the fourth conductor plate 433. Between the power semiconductor elements 155 and 157 arranged in parallel, a wiring board 372 is provided on the conductor plates 431 and 433. Signal wiring is provided on the wiring board 372 to connect the power semiconductor elements 155 and 157 to signal terminals such as the lower arm gate terminal 325L, the lower arm Kelvin emitter signal terminal 325K, the mirror emitter sense signal terminal 325M, and the upper arm gate terminal 325U. Chip resistors are provided on the signal wiring connected to the gates of the power semiconductor elements 155 and 157.

[0042] When the power conversion device 200 is configured using the semiconductor device 300', the power conversion device 200 may be required to have high output corresponding to a large current and high functionality such as fault diagnosis. However, since the power semiconductor elements 155 and 157 have a limit to the current that can be passed through them, it is effective to use the power semiconductor elements 155 and 157 in multiple parallel connections as shown in FIG. 12(a) in order to increase the output. When using multiple parallel connections, the number of gate wirings for switching the power semiconductor elements 155 and 157 increases by the number of chips, and complex wiring is required. For this reason, by using a wiring board 372 that can be multilayered compared to a lead frame and is compatible with fine wiring, it is possible to alleviate the congestion of wiring when the power semiconductor elements 155 and 157 are arranged in multiple parallel connections.

[0043] Also, the gate wiring requires a gate resistor to add a charge required for driving to the gates of the power semiconductor elements 155 and 157. Such a gate drive circuit is usually mounted on a wiring board provided outside the semiconductor device, but when the power semiconductor elements 155 and 157 are used in multiple parallel configuration, it is desirable to provide a gate resistor for each element to prevent malfunction. For this reason, a wiring board 372 on which a gate resistor is mounted as a chip resistor is built into the semiconductor device 300'. When such a wiring board 372 is mounted, the total area of ​​the contact area between the conductor plates 430 and 431 and the insulating sheets 440 and 441 becomes larger than the total area of ​​the element bonding area 462 of the power semiconductor elements 155 and 157, and the pressure applied to the contact area between the conductor plates 430 and 431 and the insulating sheets 440 and 441 is significantly reduced. Therefore, by providing the above-mentioned resin filling space 460, the total area of ​​the contact area is reduced, which is effective in improving insulation.

[0044] Fig. 12(b) is a cross-sectional view of the semiconductor device 300 in the modified example. Fig. 12(b) is a cross-sectional view of the line BB shown in Fig. 12(a). Note that the cross-sectional view shows a state in which the first conductor plate (upper arm circuit emitter side) 430, the first sheet member (emitter side) 440, and the cooling member 340, which are removed in Fig. 12(a), are provided.

[0045] In Figure 12(b), as explained with reference to Figure 2, the emitter-side conductor plate 430 has an element junction region 462 to which the power semiconductor element 155 is bonded, and a connection region 463 to which the element junction regions 462 are connected, and also has a protrusion 461 directly above the element junction region 462.

[0046] The protruding portion 461 is bonded to the insulating sheet 440 in the contact region 464. In the connecting region 463, a resin filling space 460 is formed between the insulating sheet 440 and the first conductive plate 430, and the resin filling space 460 is filled with the resin member 360 in the transfer molding process.

[0047] Like the emitter-side conductor plate 430, the collector-side conductor plate 441 is also formed with a protrusion 461 and a resin-filled space 460. By providing the resin-filled space 460 on the collector side as well, the design constraint of pressing and pressurizing the collector-side conductor plate against the insulating sheet 441 is eliminated by clamping the terminal with a mold in the transfer molding process, and the design freedom is improved.

[0048] 13 is a diagram showing the relationship between the amount of shrinkage and temperature of the resin member 360. The horizontal axis represents temperature, and the vertical axis represents the amount of shrinkage. The resin members α and γ shown in FIG. 13 shrink by a large amount up to the glass transition temperatures αt and γt when the glass transition temperatures αt and γt are lower than Tmold, respectively, and shrink by a smaller amount when the temperature becomes lower than the glass transition temperatures αt and γt. The resin member β shrinks by a constant amount when the glass transition temperature is lower than Tmold. T1 is the minimum value of the use environment temperature of the semiconductor device 300', and T2 is the maximum value of the use environment temperature, for example, T1 is -40°C and T2 is 125°C. Tmold is, for example, 175°C. In this temperature range, when the shrinkage amount is larger than copper Cu, that is, when the shrinkage amount of the resin member 360 is within the hatched area H shown in FIG. 13, a convex portion 466 facing the resin filling space 460 can be provided on the insulating sheets 440 and 441 in the use temperature range T1-T2 as described below.

[0049] The principle of forming the convex portion 466 on the insulating sheets 440, 441 by the protruding portion 461 and the resin filling space 460 will be described with reference to FIG. 13. For example, the resin member 360 is injected into the transfer mold die at a Tmold temperature of 175°C. The shrinkage in the Z-axis direction of the components of the semiconductor device 300' is focused on based on the dimensions immediately after injection. Looking at the components from the emitter side to the collector side, they are the insulating sheet 440, the conductor plate 430, the solder, the power semiconductor element 155, the solder, the conductor plate 431, and the insulating sheet 441. The insulating sheets 440, 441 are composed of the resin insulating layers 442, 443 having a thickness of 100 μm to 500 μm and the metal foil 444 having a thickness of 30 μm to 200 μm. The conductor plates 430, 431 are composed of a copper-based material having a thickness of 1 mm to 5 mm. The solder is composed of a tin-based material having a thickness of 50 μm to 200 μm. The power semiconductor element 155 is made of a silicon-based material with a thickness of 80 μm to 200 μm. Although it is made of various materials, in this embodiment, the amount of shrinkage of each of these components in the Z-axis direction is described by approximating the amount of thermal shrinkage of pure copper (Cu), which represents the copper-based material that is the thickest component material.

[0050] After the resin member 360 is injected into the transfer mold, it hardens and shrinks as the hardening reaction progresses. The amount of hardening shrinkage varies depending on the composition of the resin member 360. It varies depending on the ratio of the epoxy resin component that hardens and the ratio of other fillers that do not harden, and the greater the ratio of the epoxy resin component, the greater the amount of hardening shrinkage. Even if the ratio of the epoxy resin component is the same, the greater the ratio of the epoxy group, which is a reactive component in the epoxy resin component, the greater the amount of hardening shrinkage. The semiconductor device 300' taken out of the transfer mold is cooled to room temperature. If the glass transition temperature is lower than Tmold, it shrinks at a large shrinkage rate up to the glass transition temperature, and if it becomes lower than the glass transition temperature, it shrinks at a smaller shrinkage rate. If the glass transition temperature is higher than Tmold, it shrinks at a constant shrinkage rate. T1 is the minimum value of the operating environment temperature of the semiconductor device 300', and T2 is the maximum value of the operating environment temperature. For example, T1 is -40°C and T2 is 125°C. In this temperature range, when the amount of shrinkage is greater than Cu, that is, when the amount of shrinkage of resin member 360 is within hatched area H, resin member 360 shrinks more than Cu in the operating temperature range, and thus protrusions 466 are formed on insulating sheets 440, 441. In a modification of this embodiment, by using resin members β and γ shown in FIG. 13 as resin member 360, protrusions 466 can be formed on insulating sheets 440, 441.

[0051] By providing the protrusions 466 on the insulating sheets 440 and 441, the protrusions 461, which are the main heat dissipation parts, can easily come into contact with the cooling member 340 via the heat conductive member 453 and the insulating sheets 440 and 441, improving the cooling performance. Furthermore, the presence of the protrusions 466 allows the heat conductive member 453 to be locally thickened in the area where the protrusions 466 are formed, and when an adhesive type heat conductive member 453 is used, the stress is reduced and adhesion can be maintained for a long period of time, resulting in an effect of high reliability. Furthermore, when a non-adhesive type heat conductive member 453 is used, the presence of the protrusions 466 holds the heat conductive member 453 and suppresses a decrease in thermal resistance due to pump-out, resulting in an effect of high reliability.

[0052] FIG. 14 is a circuit diagram of a power conversion device 200 using the semiconductor devices 300 and 300'. The power conversion device 200 includes inverter circuits 140 and 142, an inverter circuit 43 for auxiliary equipment, and a capacitor module 500. The inverter circuits 140 and 142 include a plurality of semiconductor devices 300 and 300', which are connected to form a three-phase bridge circuit. When the current capacity is large, the semiconductor devices 300 and 300' are further connected in parallel, and these parallel connections are made corresponding to each phase of the three-phase inverter circuit, thereby making it possible to handle an increase in the current capacity. In addition, the active elements 155 and 157 and the diodes 156 and 158, which are power semiconductor elements built into the semiconductor devices 300 and 300', are also connected in parallel to handle an increase in the current capacity.

[0053] The inverter circuit 140 and the inverter circuit 142 have the same basic circuit configuration, and the control method and operation are also basically the same. Since the outline of the circuit operation of the inverter circuit 140 and the like is well known, a detailed description thereof will be omitted here.

[0054] The upper arm circuits of the inverter circuits 140, 142 include an upper arm active element 155 and an upper arm diode 156 as switching power semiconductor elements, and the lower arm circuits include a lower arm active element 157 and a lower arm diode 158 as switching power semiconductor elements. The active elements 155, 157 perform switching operation upon receiving a drive signal output from one or the other of the two driver circuits constituting the driver circuit 174, and convert the DC power supplied from the battery 136 into three-phase AC power.

[0055] Active element 155 of the upper arm circuit and active element 157 of the lower arm circuit each have a collector electrode, an emitter electrode, and a gate electrode. Diode 156 of the upper arm circuit and diode 158 of the lower arm circuit each have two electrodes, a cathode electrode and an anode electrode. As shown in Fig. 6, the cathode electrodes of diodes 156 and 158 are electrically connected to the collector electrodes of IGBTs 155 and 157, and the anode electrodes are electrically connected to the emitter electrodes of active elements 155 and 157, respectively. As a result, the current flows in the forward direction from the emitter electrode to the collector electrode of active element 155 for the upper arm and active element 157 for the lower arm. It should be noted that a MOSFET (metal oxide semiconductor field effect transistor) may be used as the active element, in which case the upper arm diode 156 and the lower arm diode 158 are not necessary.

[0056] Positive terminal 315B and negative terminal 319B of each upper and lower arm series circuit are respectively connected to DC terminals for connecting capacitors of capacitor module 500. AC power is generated at the connection part between the upper arm circuit and the lower arm circuit, and this connection part is connected to AC side terminals 320B of semiconductor devices 300, 300'. AC side terminals 320B of semiconductor devices 300, 300' of each phase are respectively connected to AC output terminals of power conversion device 200, and the generated AC power is supplied to the stator windings of motor generator 192 or 194.

[0057] The control circuit 172 generates a timing signal for controlling the switching timing of the upper arm active element 155 and the lower arm active element 157 based on input information from a vehicle-side control device and a sensor (e.g., a current sensor 180). The driver circuit 174 generates a drive signal for performing a switching operation on the upper arm active element 155 and the lower arm active element 157 based on the timing signal output from the control circuit 172. Reference numeral 181 denotes a connector.

[0058] The upper and lower arm series circuits include a temperature sensor (not shown), and temperature information about the upper and lower arm series circuits is input to control circuit 172. In addition, voltage information about the DC positive side of the upper and lower arm series circuits is input to control circuit 172. Based on this information, control circuit 172 performs over-temperature detection and over-voltage detection, and if over-temperature or over-voltage is detected, control circuit 172 stops the switching operation of all upper arm active elements 155 and lower arm active elements 157, thereby protecting the upper and lower arm series circuits from over-temperature or over-voltage.

[0059] FIG. 15 is an external perspective view of the power conversion device 200 shown in FIG. 14, and FIG. 16 is a cross-sectional view of the power conversion device 200 shown in FIG. 15 taken along line XV-XV.

[0060] The power converter 200 includes a housing 12 that is formed of a lower case 11 and an upper case 10 and is formed in a substantially rectangular parallelepiped shape. An electric circuit body 400, a capacitor module 500, and the like are housed inside the housing 12. The electric circuit body 400 has a cooling flow path, and a cooling water inlet pipe 13 and a cooling water outlet pipe 14 that communicate with the cooling flow path protrude from one side of the housing 12. As shown in FIG. 16, the lower case 11 has an opening on the upper side (Z direction), and the upper case 10 is attached to the lower case 11 by closing the opening of the lower case 11. The upper case 10 and the lower case 11 are formed of an aluminum alloy or the like, and are fixed in a sealed manner from the outside. The upper case 10 and the lower case 11 may be integrally configured. The housing 12 is formed in a simple rectangular parallelepiped shape, which makes it easy to attach to a vehicle or the like and also easy to produce.

[0061] A connector 17 is attached to one side surface in the longitudinal direction of the housing 12, and an AC terminal 18 is connected to this connector 17. In addition, a connector 21 is provided on the surface from which the cooling water inlet pipe 13 and the cooling water outlet pipe 14 are led out.

[0062] As shown in FIG. 16, an electric circuit body 400 is accommodated in the housing 12. A control circuit 172 and a driver circuit 174 are arranged above the electric circuit body 400, and a capacitor module 500 is accommodated on the DC terminal side of the electric circuit body 400. By arranging the capacitor module 500 at the same height as the electric circuit body 400, the power conversion device 200 can be made thinner, improving the degree of freedom of installation in a vehicle. An AC side terminal 320B of the electric circuit body 400 is connected to a bus bar 361 through a current sensor 180. In addition, a positive side terminal 315B and a negative side terminal 319B, which are DC terminals of the semiconductor device 300, 300', are respectively connected to positive and negative terminals 362A, 362B of the capacitor module 500.

[0063] According to the embodiment described above, the following advantageous effects can be obtained. (1) The semiconductor device 300, 300' includes a plurality of power semiconductor elements 155, 156, 157, 158, conductive plates 430, 431, 432, 433 to which the plurality of power semiconductor elements 155, 156, 157, 158 are joined, insulating sheets 440, 441 bonded to the surfaces of the conductive plates 430, 431, 432, 433 opposite to the surface on which the plurality of semiconductor elements are joined, and a resin member 360 that seals the plurality of power semiconductor elements 155, 156, 157, 158, the insulating sheets 440, 441, and the conductive plates 430, 431, 432, 433. 32, 433 have a plurality of element bonding regions 462 to which the plurality of power semiconductor elements 155, 156, 157, 158 are bonded, and a connection region 463 provided between the plurality of element bonding regions 462, and the insulating sheet side surfaces of the element bonding regions 462 of the conductor plates 430, 431, 432, 433 protrude from the insulating sheet side surfaces of the connection regions 463 and are bonded to the insulating sheets 440, 441, and a resin member 360 is filled between the insulating sheet side surfaces of the connection regions 463 of the conductor plates 430, 431, 432, 433 and the insulating sheets 440, 441. This makes it possible to provide highly reliable semiconductor devices 300, 300' with improved insulation by the insulating sheets 440, 441.

[0064] The present invention is not limited to the above-described embodiment, and other embodiments that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. In addition, the above-described embodiment may be combined with a modified example. [Explanation of symbols]

[0065] 10 upper case, 11 lower case, 12 housing, 13 cooling water inlet pipe, 14 cooling water outlet pipe, 17, 21 connector, 18 AC terminal, 43, 140, 142 inverter circuit, 155 first power semiconductor element (upper arm circuit active element), 156 first power semiconductor element (upper arm circuit diode), 157 second power semiconductor element (lower arm circuit active element), 158 second power semiconductor element (lower arm circuit diode), 172 control circuit, 174 driver circuit, 180 current sensor, 181 connector motor generator, 192, 194, motor generator, 200, power converter, 300, 300', semiconductor device, 315B, positive electrode side terminal, 319B, negative electrode side terminal, 320B, AC side terminal, 325, signal terminal, 325K, Kelvin emitter signal terminal, 325L, lower arm gate terminal, 325M, mirror emitter signal terminal, 325U, upper arm gate terminal, 340, cooling section material, 360...resin member, 372...wiring board, 400...electric circuit body, 430...first conductor plate (upper arm circuit emitter side), 431...second conductor plate (upper arm circuit collector side), 432...third conductor plate (lower arm circuit emitter side), 433...fourth conductor plate (lower arm circuit collector side), 440...first insulating sheet (emitter side), 441...second insulating sheet (collector side), 442...first insulating sheet (emitter side), First resin insulating layer (emitter side), 443...second resin insulating layer (collector side), 444...metal foil, 453...thermal conductive member, 460...resin filled space, 461...protrusion, 462...element bonding region, 463...connecting region, 464...adhesion region, 465...void, convex portion...466, 500...capacitor module, 601...transfer molding device, 602...spring.

Claims

1. a plurality of semiconductor elements; a conductor plate to which the plurality of semiconductor elements are bonded; an insulating sheet adhered to a surface of the conductor plate opposite to the surface of the plurality of semiconductor elements; and a resin member that seals the plurality of semiconductor elements, the insulating sheet, and the conductor plate; The conductor plate has a plurality of element bonding regions to which each of the plurality of semiconductor elements is bonded, and a connection region provided between the plurality of element bonding regions, the insulating sheet side surface of the conductor plate in the element bonding regions protruding beyond the insulating sheet side surface of the connection regions and adhered to the insulating sheet, and the resin member is filled between the insulating sheet side surface of the conductor plate in the connection regions and the insulating sheet.

2. 2. The semiconductor device according to claim 1, The insulating sheet includes a resin insulating layer, and the resin insulating layer and the resin member are in close contact with each other through the penetration of resin components therebetween.

3. 2. The semiconductor device according to claim 1, A resin-filled space into which the resin member is filled is formed between the insulating sheet side surface of the connection region and the insulating sheet, and the resin member in the resin-filled space is connected to a resin member that seals the multiple semiconductor elements, the insulating sheet, and the conductor plate.

4. 4. The semiconductor device according to claim 3, The thickness of the resin-filled space is equal to or greater than the thickness of the insulating sheet.

5. 5. The semiconductor device according to claim 4, The insulating sheet has a laminated structure of a resin insulating layer and a metal foil, The thickness of the resin filled space is equal to or greater than the thickness of the resin insulating layer.

6. 2. The semiconductor device according to claim 1, the conductive plate and the insulating sheet are disposed on both sides of the semiconductor elements, A semiconductor device in which a resin filling space into which the resin material is filled is formed between the conductor plate and the insulating sheet arranged on both sides, and between the insulating sheet side surface of the connecting region and the insulating sheet.

7. 7. The semiconductor device according to claim 6, The insulating sheet has a protrusion formed toward the resin filling space.

8. 8. A power conversion device comprising the semiconductor device according to claim 1, for converting DC power into AC power.

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