Electrical circuit bodies and power converters

Abstract

To improve the insulation reliability of an insulation sheet.SOLUTION: An electric circuit body comprises: a semiconductor device formed by integrally sealing a semiconductor element, a conductor plate to which the semiconductor device is bonded, an insulation sheet which is adhered to a heat radiation surface of the conductor plate using a sealant; a cooling member which is arranged so as to be opposite to the semiconductor device, and cools heat generated by the semiconductor device; and a heat conduction member which is arranged between the insulation sheet and the cooling member. The insulation sheet includes: a resin insulation layer which covers the conductor plate on one surface, and is bonded to the heat radiation surface of the conductor plate; and a front surface conductive layer that is exposed to a front surface of the semiconductor device while being bonded to the other surface of the resin insulation layer. In a region on an outer peripheral side of an adhesive region of the conductor plate and the resin insulation layer in a projection region of the front surface conductive layer, a conductive connection part which electrically connects the front surface conductive layer and the cooling member with each other is formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Power conversion devices that utilize the switching operation of semiconductor elements are widely used in consumer electronics, automotive, railway, and substation equipment due to their high conversion efficiency. Semiconductor elements generate heat when energized. Therefore, cooling elements are provided to cool the semiconductor elements, and an insulating sheet is placed between the semiconductor device containing the semiconductor elements and the cooling element positioned opposite it. Cooling of semiconductor devices requires high reliability to maintain heat dissipation, especially in automotive applications.

[0003] Patent Document 1 discloses a semiconductor device in which a terminal member is provided, one end of which is electrically connected to a conductor layer inside the molded resin, and the other end of which protrudes from the molded resin and is electrically connected to a cooling means, and the conductor layer and the cooling means are electrically connected via this terminal member. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-033872 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The semiconductor device described in Patent Document 1 suffers from reduced insulation reliability of the insulating sheet. [Means for solving the problem]

[0006] The electrical circuit body according to the present invention comprises a semiconductor device formed by integrally sealing a semiconductor element, a conductor plate to which the semiconductor element is joined, and an insulating sheet adhered to the heat dissipation surface of the conductor plate with a sealing material; a cooling member disposed opposite the semiconductor device for cooling the heat generated by the semiconductor element; and a heat conductive member disposed between the insulating sheet and the cooling member. The insulating sheet has a resin insulating layer that covers the conductor plate on one side and is adhered to the heat dissipation surface of the conductor plate, and a surface conductor layer that is adhered to the other side of the resin insulating layer and is exposed on the surface of the semiconductor device. A conductive connection portion is formed in the projection region of the surface conductor layer and in the region on the outer periphery side of the adhesion region between the conductor plate and the resin insulating layer, electrically connecting the surface conductor layer and the cooling member to each other. [Effects of the Invention]

[0007] According to the present invention, the insulation reliability of an insulating sheet can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view of an electrical circuit according to an embodiment. [Figure 2] This is a cross-sectional view of the electrical circuit body along line XX. [Figure 3] This is a cross-sectional perspective view of the electrical circuit along the YY line. [Figure 4] This is a cross-sectional perspective view of an electrical circuit along line XX. [Figure 5] This is a semi-transparent plan view of a semiconductor device. [Figure 6] This is a circuit diagram of a semiconductor device. [Figure 7] (a) to (d) are cross-sectional views illustrating the manufacturing process of semiconductor devices. [Figure 8] (a)(b) These are cross-sectional views illustrating the manufacturing process of an electrical circuit. [Figure 9] (a)(b) These are enlarged cross-sectional views of the main parts of Comparative Example 1 and Comparative Example 2. [Figure 10] (a)(b) These are cross-sectional views of the XX and YY lines of Modified Example 1. [Figure 11] (a) and (b) are cross-sectional views of the X-X and Y-Y lines of Modification 2. [Figure 12] (a) to (d) are semi-transparent plan views of Modifications 3 to 6. [Figure 13] It is a circuit diagram of a power conversion device. [Figure 14] It is an external perspective view of a power conversion device. [Figure 15] It is a cross-sectional perspective view of the XV-XV line of a power conversion device.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments 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 for the sake of clarity of explanation, appropriate omissions and simplifications are made. The present invention can also be implemented in various other forms. Unless otherwise particularly limited, each component may be singular or plural.

[0010] The positions, sizes, shapes, ranges, etc. of each component shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0011] FIG. 1 is a plan view of an electric circuit body 400 according to an embodiment. The electric circuit body 400 is composed of a semiconductor device 300 and a cooling member 340. In the example shown in FIG. 1, the electric circuit body 400 is provided with three semiconductor devices 300 in parallel.

[0012] The semiconductor device 300 contains semiconductor elements 155 and 157, described later, which are sealed with a encapsulating material 360. Both sides of the semiconductor device 300 dissipate heat generated by the switching operation of the semiconductor elements 155 and 157. Furthermore, terminals connected to the semiconductor elements 155 and 157 are led out from the encapsulating material 360 on the sides of the semiconductor device 300. These terminals are power terminals through which large currents flow, such as the positive terminal 315B and negative terminal 319B connected to the capacitor module 500 (see Figure 13) of the DC circuit, and the AC terminal 320B connected to the motor generators 192 and 194 (see Figure 13) of the AC circuit. In addition, terminals led out from the encapsulating material 360 on the sides of the semiconductor device 300 include the lower arm gate terminal 325L, the collector sense terminal 325C, the emitter sense terminal 325E, and the upper arm gate terminal 325U. An electrical circuit 400, comprising three semiconductor devices 300 arranged in parallel, functions as a power converter 200 that converts DC current and AC current through the switching operation of semiconductor elements 155 and 157. The number of semiconductor devices 300 in the electrical circuit 400 is not limited to three, but can be arbitrarily set to suit various configurations of the electrical circuit 400.

[0013] The cooling member 340 is positioned opposite the semiconductor device 300 and cools the heat generated by the switching operation of the semiconductor elements 155 and 157. Specifically, the cooling member 340 has a flow channel through which a refrigerant flows, and the refrigerant flowing through the channel cools the heat generated from the semiconductor device 300. The refrigerant used is water or an antifreeze solution made by mixing ethylene glycol with water. The cooling member 340 is preferably made of lightweight aluminum with high thermal conductivity. It is manufactured by extrusion molding, forging, brazing, etc.

[0014] Figure 2 is a cross-sectional view of the electrical circuit body 400 shown in Figure 1 along line XX, and Figure 3 is a cross-sectional perspective view of the electrical circuit body 400 shown in Figure 1 along line YY. Figure 4 is a cross-sectional perspective view of the electrical circuit body 400 shown in Figure 1 along line XX, but shows the semiconductor device 300 with the cooling member 340 and heat conductive member 453 removed from the electrical circuit body 400.

[0015] As shown in Figure 2, the electrical circuit body 400 is equipped with a pressurizing mechanism 341 that pressurizes the cooling members 340 provided on both sides of the semiconductor device 300 by sandwiching them from both sides. The pressurizing mechanism 341, although simplified in the illustration, is a mechanism that, for example, connects the cooling members 340 on both sides to each other with screws or the like and applies pressure to the semiconductor device 300 side.

[0016] As shown in Figure 2, the first semiconductor element forming the upper arm circuit of the power converter includes an active element 155 and a diode 156 (see Figures 5 and 6 described later). Si, SiC, GaN, GaO, C, etc., can be used as the active element. If the body diode of the active element 155 is used, the separate diode may be omitted. The collector side of the first semiconductor element 155 is joined to the second conductor plate 431. Solder or sintered metal may be used for this joining. The emitter side of the first semiconductor element 155 is joined to the first conductor plate 430.

[0017] As shown in Figure 3, the lower arm circuit is formed by a second semiconductor element comprising an active element 157 and a diode 158 (see Figures 5 and 6 described later). As shown in Figure 3, the collector side of the second semiconductor element 157 is bonded to the fourth conductor plate 433. The emitter side of the second semiconductor element 157 is bonded to the third conductor plate 432.

[0018] The conductive plates 430, 431, 432, and 433 are not particularly limited as long as they are made of materials with high electrical and thermal conductivity, but it is desirable to use metallic materials such as copper-based or aluminum-based materials, or composite materials such as diamond, carbon, or ceramics with high thermal conductivity. These may be used alone, but they may also be plated with Ni or Ag to improve bonding with solder or sintered metals.

[0019] As shown in Figures 2, 3, and 4, the conductor plates 430, 431, 432, and 433 not only conduct electric current but also act as heat transfer members, transferring heat generated by the semiconductor elements 155, 156, 157, and 158 to the cooling member 340. The sides of the conductor plates 430, 431, 432, and 433 opposite to the sides joined to the semiconductor elements 155, 156, 157, and 158 become the heat dissipation surfaces. Since the conductor plates 430, 431, 432, and 433 and the cooling member 340 have different potentials, insulating sheets 440 and 441 are used between them and the heat dissipation surfaces.

[0020] The insulating sheets 440 and 441 are constructed by laminating a resin insulating layer 443, a surface conductor layer 444, and an intermediate conductor layer 445. The resin insulating layer 443 covers the conductor plates 430, 431, 432, and 433 on one side and is bonded to the heat dissipation surfaces of the conductor plates 430, 431, 432, and 433. The surface conductor layer 444 is bonded to the other side of the resin insulating layer 443 and is exposed on the surface of the semiconductor device 300. The intermediate conductor layer 445 is made of a conductive material and is embedded in the resin insulating layer 443 at approximately the middle of its thickness.

[0021] The resin insulating layer 443 of the insulating sheets 440 and 441 is not particularly limited as long as it has adhesive properties with respect to the conductor plates 430, 431, 432, and 433, but an epoxy resin-based insulating layer with dispersed powdered inorganic filler is preferable. This is because it offers a good balance between adhesion and heat dissipation. The insulating sheets 440 and 441 are provided with a surface conductive layer 444, such as metal foil, on the side that contacts the heat conductive member 453 described later. Furthermore, the planar size of the intermediate conductive layer 445 embedded in the resin insulating layer 443 of the insulating sheets 440 and 441 is equal to or slightly larger than the projected position of the conductor plates 430, 431, 432, and 433. When the intermediate conductive layer 445 is embedded in the resin insulating layer 443, the insulating sheets 440 and 441 can be made to withstand higher voltages by utilizing voltage sharing. The intermediate conductive layer 445 is provided as appropriate depending on the degree and necessity of increasing the withstand voltage.

[0022] The insulating sheets 440 and 441 are cured simultaneously with the sealant 360 during the transfer molding process. When the insulating sheets 440 and 441 are mounted on the mold during the transfer molding process, a release sheet or a surface conductive layer 444 is provided on the contact surface between the insulating sheets 440 and 441 and the mold to prevent adhesion to the mold. Release sheets have poor thermal conductivity and therefore require a peeling process after transfer molding. However, if a surface conductive layer 444 such as metal foil is used, it can be used without peeling after transfer molding by selecting a metal with high thermal conductivity, such as copper or aluminum.

[0023] Furthermore, in the transfer molding process, the uncured sealant 360 is injected into the mold at a predetermined pressure. This molding pressure causes the insulating sheets 440 and 441 to deform and conform to the recesses provided in the mold, forming protrusions toward the cooling member 340. These protrusions become conductive connection parts 460 that electrically connect the surface conductive layer 444 of the insulating sheets 440 and 441 to the cooling member 340. Details of the conductive connection parts 460 will be described later.

[0024] The semiconductor elements 155, 156, 157, 158, the conductor plates 430, 431, 432, 433, and the insulating sheets 440, 441 are sealed with a sealing material 360 by transfer molding to constitute the semiconductor device 300.

[0025] The heat conduction member 453 is placed between the semiconductor device 300 and the cooling member 340 to reduce contact thermal resistance. The heat conduction member 453 can be a material that is fluid at room temperature or high temperature, such as grease, gel grease, or phase change sheet. However, to ensure workability and long-term reliability, a curable heat conduction material that is fluid before curing and loses its fluidity after curing is preferable. The curable heat conduction member 453 has the advantage of low viscosity and excellent workability when applied, and can improve mechanical properties after curing. Curing can be performed by heat curing, moisture curing, or UV curing, but heat curing is preferable for curing to deep layers.

[0026] The heat conductive member 453 is a material obtained by mixing a highly thermally conductive material such as metal, ceramics, or carbon-based material with a resin. The most desirable resin is silicone resin, which exhibits little change in elastic modulus from around -40°C to around 200°C. Furthermore, an insulating material is preferred for the heat conductive member 453. This is to prevent a decrease in insulation properties due to the heat conductive member 453 material adhering to the vicinity of the terminals.

[0027] When the heat conduction member 453 is made of an insulating material, the potential difference between the conductive plates 430, 431, 432, and 433 and the cooling member 340 is shared not only by the insulating sheets 440 and 441 but also by the heat conduction member 453. The insulating sheets 440 and 441 are manufactured using a vacuum process to prevent the inclusion of air layers such as voids, but the heat conduction member 453 is applied at atmospheric pressure. This is because applying the heat conduction member 453 using a vacuum process would require large equipment. When the heat conduction member 453 is applied at atmospheric pressure, it is more likely to contain air layers such as voids compared to the insulating sheets 440 and 441. When a high voltage is applied to the heat conduction member 440 and 441 containing air layers, partial discharge may occur in the air layers such as voids. When partial discharge occurs, noise is generated and the insulation reliability of the insulating sheets 440 and 441 is reduced. Details will be described later with reference to Figure 9(a).

[0028] The conductive connection portion 460 electrically connects the surface conductor layer 444 of the insulating sheets 440 and 441 of the semiconductor device 300 to the cooling member 340, thereby pre-setting the surface conductor layer 444 and the cooling member 340 to the same potential. This prevents partial discharge of the heat conductive member 453 and prevents potential fluctuations caused by dielectric breakdown of a portion of the heat conductive member 453. Furthermore, by using insulating sheets 440 and 441 with an embedded intermediate conductor layer 445, noise generation can be suppressed and the insulation reliability of the insulating sheets 440 and 441 can be maintained even when the voltage is increased by voltage sharing.

[0029] As shown in Figure 2, the conductive connection portion 460 electrically connects the surface conductor layer 444 and the cooling member 340 within the projection region 462 of the surface conductor layer 444, and in the outer peripheral region of the projection region 461 of the adhesive portion between the conductor plates 430, 431, 432, 433 and the resin insulating layer 443. The heat conductive member 453 is positioned between the surface conductor layer 444 and the cooling member 340 in a region that covers at least the projection region 461 of the adhesive portion of the resin insulating layer 443.

[0030] By positioning the conductive connection portion 460 outside the projection area 461 of the adhesive portion, a decrease in the insulating properties of the insulating sheet 440 due to peeling of the insulating sheet 440 is prevented. Details will be described later with reference to Figure 9(b). Furthermore, since the conductive connection portion 460 is positioned outside the projection area 461 of the adhesive portion, even if the resin insulating layer 443 in the conductive connection portion 460 deteriorates, it does not affect the insulating properties or heat dissipation. In addition, by providing the conductive connection portion 460 in the projection area 462 of the surface conductor layer 444, there is no need to provide separate terminals or the like to connect to the cooling member 340, which has the advantage of excellent productivity of the device.

[0031] The adhesive portions of the conductive plates 430, 431, 432, 433 and the resin insulating layer 443 are the portions where the conductive plates 430, 431, 432, 433, which are joined directly above or below the semiconductor elements 155, 156, 157, 158, are bonded to the insulating sheets 440, 441, and are responsible for both heat dissipation from the semiconductor elements 155, 156, 157, 158 and insulation. The adhesive portions of the conductive plates 430, 431, 432, 433, which are provided as dummy portions not joined directly above or below the semiconductor elements 155, 156, 157, 158, and the insulating sheets 440, 441 do not correspond to the projection region 461 of this embodiment. Therefore, a conductive connection portion 460 may be provided in the region of the adhesive portion corresponding to the dummy portion, within the projection region 462 of the surface conductive layer 444 and on the outer peripheral side of the projection region 461 of the adhesive portion of the resin insulating layer 443.

[0032] The conductive connection portion 460 is located between the semiconductor device 300 and the cooling member 340, and is positioned symmetrically on the emitter side and collector side in the stacking direction of the semiconductor device 300 and the cooling member 340. In other words, the conductive connection portion 460 located on the emitter side and the conductive connection portion 460 located on the collector side are in overlapping positions in the stacking direction of the semiconductor device 300 and the cooling member 340. As a result, when pressure is applied by the pressurizing mechanism 341, force is applied evenly to the conductive connection portion 460 from both sides, and warping due to bending stress in the insulating sheets 440 and 441 can be prevented compared to the case where the conductive connection portion 460 is located in a position where it does not overlap on the emitter side and collector side.

[0033] Figure 5 is a semi-transparent plan view of the semiconductor device 300. Figure 6 is a circuit diagram of the semiconductor device 300. As shown in Figures 5 and 6, the positive terminal 315B outputs from the collector side of the upper arm circuit and is connected to the positive side of the battery or capacitor. The upper arm gate terminal 325U outputs from the gate of the active element 155 of the upper arm circuit. The negative terminal 319B outputs from the emitter side of the lower arm circuit and is connected to the negative side of the battery or capacitor, or to GND. The lower arm gate terminal 325L outputs from the gate of the active element 157 of the lower arm circuit. The AC terminal 320B outputs from the collector side of the lower arm circuit and is connected to the motor. When neutral point grounding is performed, the lower arm circuit is connected to the negative side of the capacitor, not to GND.

[0034] The emitter sense terminal 325E of the upper arm is output from the emitter of the active element 155 of the upper arm circuit, and the emitter sense terminal 325E of the lower arm is output from the emitter of the active element 157 of the lower arm circuit. The collector sense terminal 325C of the upper arm is output from the collector of the active element 155 of the upper arm circuit, and the collector sense terminal 325C of the lower arm is output from the collector of the active element 157 of the lower arm circuit.

[0035] Furthermore, a conductive plate (upper arm circuit emitter side) 430 and a conductive plate (upper arm circuit collector side) 431 are arranged above and below the active element 155 and diode 156 of the semiconductor element (upper arm circuit). A conductive plate (lower arm circuit emitter side) 432 and a conductive plate (lower arm circuit collector side) 433 are arranged above and below the active element 157 and diode 158 of the semiconductor element (lower arm circuit).

[0036] In the example shown in Figure 5, the projection region 461 of the adhesive portion of the resin insulating layer 443 corresponding to the active element 155 and diode 156 of the semiconductor element (upper arm circuit), and the projection region 461 of the adhesive portion of the resin insulating layer 443 corresponding to the active element 157 and diode 158 of the semiconductor element (lower arm circuit), are covered by a single insulating sheet. Conductive connection portions 460, which are protrusions, are formed on the semiconductor device 300. In this example, four conductive connection portions 460 are provided within the projection region 462 of the surface conductor layer 444, which is covered by a single insulating sheet, and in the region on the outer periphery of the projection region 461 of the adhesive portion of the resin insulating layer 443. Each conductive connection portion 460 is positioned symmetrically across the projection region 461 of the adhesive portion of the resin insulating layer 443 in a planar direction intersecting the stacking direction of the semiconductor device 300 and the cooling member 240. As a result, when pressure is applied by the pressurizing mechanism 341, force is applied evenly to the conductive connection parts 460 which are arranged symmetrically in the planar direction, and it is possible to prevent the insulating sheets 440 and 441 from warping due to bending stress compared to when the conductive connection parts 460 are not arranged symmetrically in the planar direction.

[0037] The semiconductor device 300 in 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 a single module. Alternatively, a structure in which multiple upper arm circuits and lower arm circuits are integrated into a single module may be used. In this case, the number of output terminals from the semiconductor device 300 can be reduced, making it smaller.

[0038] Figures 7(a), 7(b), 7(c), and 7(d) are cross-sectional views illustrating the manufacturing process of the semiconductor device 300. Similar to Figure 2, they are shown as cross-sectional views of XX lines for one module.

[0039] Figure 7(a) shows the temporary bonding process. The collector side of semiconductor element 155 and the cathode side of semiconductor element 156 are connected to the second conductor board 431, and the gate electrode, emitter sense electrode, and collector electrode of semiconductor element 155 are connected to the gate terminal 325U, emitter sense terminal 325E, and collector sense terminal 325C of the upper arm, respectively, by wire bonding. Furthermore, the emitter side of semiconductor element 155 and the anode side of semiconductor element 156 are connected to the first conductor board 430 to fabricate the circuit body 310 on the upper arm side. Similarly, the collector side of semiconductor element 157 and the cathode side of semiconductor element 158 ​​are connected to the fourth conductor board 433, and the gate electrode, emitter sense electrode, and collector electrode of semiconductor element 157 are connected to the gate terminal 325L, emitter sense terminal 325E, and collector sense terminal 325C of the lower arm, respectively, by wire bonding.

[0040] Furthermore, the emitter side of semiconductor element 157 and the anode side of semiconductor element 158 ​​are connected to the third conductor plate 432 to fabricate the lower arm circuit body 310. However, in Figure 7(a), only the upper arm circuit body 310 is shown, and the lower arm circuit body 310 is not shown. After that, insulating sheets 440 and 441 are temporarily attached to the conductor plates 430 to 433. Temporary attachment means that the insulating sheets 440 and 441 are temporarily attached using their adhesive strength, leaving room for them to harden and bond during the subsequent transfer molding process.

[0041] Figures 7(b) to 7(d) show the transfer molding process. The transfer molding apparatus 601 is equipped with a spring 602 in the mold 603. This spring 602 allows a predetermined load to be applied to the semiconductor elements 155 to 158 without applying excessive pressure, even if the height of the circuit body 310 varies. The transfer molding apparatus 601 is also equipped with a vacuum degassing mechanism (not shown). Vacuum degassing compresses voids even if the sealing material 360 made of resin or the like encases them, thereby improving insulation. Furthermore, covering the circuit body 310 with a release film (not shown) protects against resin burrs entering the spring drive unit and the like.

[0042] As shown in Figure 7(b), the circuit body 310 with insulating sheets 440 and 441 temporarily attached is set in a mold 603 that has been preheated to a constant temperature of 175°C. The mold 603 is provided with a recess 604. This recess 604 is for forming a projection that will become a conductive connection part 460. Next, as shown in Figure 7(c), the upper and lower molds 603 are clamped together. At this time, the insulating sheets 440 and 441 and the conductive plates 430 to 433 are pressed together by the spring 602.

[0043] Next, as shown in Figure 7(d), the sealing material 360 is injected into the mold 603. The molding pressure 456 applied by the injection of the sealing material 360 causes the insulating sheets 440 and 441 to deform and conform to the recesses 604 provided in the mold 603, forming protrusions on the insulating sheets 440 and 441 that will become conductive connection parts 460. In this way, by providing recesses 604 in the transfer mold, protrusions that will become conductive connection parts 460 can be easily formed on the sealing material 360. After that, the resin-sealed semiconductor device 300 is removed from the transfer mold 601 and post-curing is performed at 175°C for 2 hours or more.

[0044] Figures 8(a) and 8(b) are cross-sectional views illustrating the manufacturing process of the electrical circuit body 400. This process is carried out using the semiconductor device 300 manufactured by the process shown in Figure 7(d). Figure 8(a) shows the coating process. The heat conductive member 453 is applied to the cooling member 340. The application position of the heat conductive member 453 is set so as not to overlap with the conductive connection portion 460, preventing the heat conductive member 453 from covering the conductive connection portion 460 when it spreads wet.

[0045] Figure 8(b) shows the adhesion and curing process. The cooling member 340 coated with the heat conductive member 453 is brought into close contact with the semiconductor device 300 by the pressurizing mechanism 341. As a result, the conductive connection portion 460 comes into contact with the cooling member 340, and the surface conductive layer 444 of the insulating sheets 440 and 441 and the cooling member 340 are electrically connected to each other. Then, the electrical circuit body 400 is fabricated by curing the heat conductive member 453.

[0046] Figure 9(a) is Comparative Example 1, and Figure 9(b) is Comparative Example 2, both showing enlarged cross-sectional views of the main part of the electrical circuit body 400' along line XX. Comparative Examples 1 and 2 illustrate examples where the present invention is not applied, in order to understand the present invention.

[0047] In Comparative Example 1 shown in Figure 9(a), the conductive connection portion 460 is not provided, compared to the embodiment shown in Figure 2. The capacitance between the cooling member 340 and the surface conductor layer 444 is C tim The capacitance between the surface conductor layer 444 and the intermediate conductor layer 445 is C sheet1 The capacitance between the intermediate conductor layer 445 and the conductor plate 420 is C sheet2 The cooling member 340 is grounded, and a potential is applied between the cooling member 340 and the conductor plate 420, but this potential is V according to each capacitance. tim , V sheet1 , V sheet2 The potential is distributed among the elements.

[0048] If there is an air layer such as a void 457 in the heat conductive member 453, the potential V timWhen it is high, partial discharge may occur in void 457. Noise may be generated due to this partial discharge. Also, by repeating the partial discharge, a part of the heat conduction member 453 is damaged by dielectric breakdown, and a potential fluctuation occurs in which the cooling member 340 and the surface conductor layer 444 become the same potential. As a result, the insulation reliability of the insulating sheets 440 and 441 is reduced.

[0049] Furthermore, using the intermediate conductor layer 445, C sheet1 and C sheet2 are made equal, and the case where the potential V sheet1 and the potential V sheet2 are made equal and the withstand voltage is increased is considered. When partial discharge occurs in the void 457 in the heat conduction member 453, a part of the heat conduction member 453 is damaged by dielectric breakdown, and when the potential V tim applied to the heat conduction member 453 is short-circuited, an excessive voltage is temporarily applied to the potential V sheet1 between the surface conductor layer 444 and the intermediate conductor layer 445, reducing the insulation reliability of the insulating sheets 440 and 441. Also, by repeating the partial discharge, potential fluctuations occur, disturbing the voltage sharing between the cooling member 340, the surface conductor layer 444, and the intermediate conductor layer 445, thus reducing the insulation reliability of the insulating sheets 440 and 441.

[0050] On the other hand, according to the present embodiment, by providing the conductive connection portion 460 and making the surface conductor layer 444 and the cooling member 340 have the same potential in advance, partial discharge of the heat conduction member 453 can be prevented, generation of noise can be suppressed, and the insulation reliability of the insulating sheets 440 and 441 can be maintained.

[0051] In Comparative Example 2 shown in Fig. 9(b), an example is shown in which a convex portion 343 is provided on the cooling member 340 within the projection area 461 of the adhesion portion between the conductor plate 420 and the resin insulation layer 443 as compared with the present embodiment shown in Fig. 2.

[0052] As shown in Figure 9(b), the protrusion 343 on the cooling member 340 is electrically connected to the surface conductor layer 444 of the insulating sheet 440. However, since the protrusion 343 is located opposite the conductor plate 420 with the insulating sheet 440 in between, the pressing force of the pressing mechanism 341 is partially concentrated on the insulating sheet 440 via the protrusion 343 of the cooling member 340. The resin insulating layer 443 of the insulating sheet 440 is composed of a high thermal conductivity filler 447 and a resin binder 448, as shown in the partially enlarged cross-sectional view B of Figure 9(b). If excessive stress is partially applied to the resin insulating layer 443, delamination 448 occurs between the high thermal conductivity filler 447 and the resin binder 448. This delamination 448 reduces the insulating properties of the insulating sheet 440, which is essential for insulation from the conductor plate 420.

[0053] On the other hand, according to this embodiment, by arranging the conductive connection portion 460 outside the projection area 461 of the adhesive portion, the insulation reliability of the insulating sheets 440 and 441 can be maintained.

[0054] Figures 10(a) and 10(b) show a modified example of this embodiment, where Figure 10(a) is a cross-sectional view corresponding to line XX of the electrical circuit body 400 shown in Figure 1, and Figure 10(b) is a cross-sectional view corresponding to line YY of the electrical circuit body 400 shown in Figure 1.

[0055] As shown in Figures 10(a) and 10(b), the cooling member 340 has a protrusion facing the semiconductor device 300, formed within the projection region 462 of the surface conductor layer 444, in the outer peripheral region of the projection region 461 of the conductor plates 430, 431 and the resin insulating layer 443. The conductive connection portion 460 electrically connects the cooling member 340 to the surface conductor layer 444 of the insulating sheets 440, 441 via this protrusion.

[0056] In this modified example 1, partial discharge of the heat conductive member 453 is prevented, noise generation is suppressed, and the insulation reliability of the insulating sheets 440 and 441 is maintained. Even if the resin insulating layer 443 in the conductive connection part 460 deteriorates, it does not affect the insulation or heat dissipation.

[0057] Figures 11(a) and 11(b) show a second modification of this embodiment, where Figure 11(a) is a cross-sectional view corresponding to line XX of the electrical circuit body 400 shown in Figure 1, and Figure 11(b) is a cross-sectional view corresponding to line YY of the electrical circuit body 400 shown in Figure 1.

[0058] As shown in Figures 11(a) and 11(b), a conductive member is provided between the semiconductor device 300 and the cooling member 340, within the projection region 462 of the surface conductive layer 444, and in the outer peripheral region of the projection region 461 of the conductive plates 430, 431 and the resin insulating layer 443. The conductive connection portion 460 is configured by electrically connecting the cooling member 340 and the surface conductive layer 444 of the insulating sheets 440, 441 via this conductive member. The conductive member is, for example, a conductive adhesive containing materials such as aluminum, copper, or silver.

[0059] In this modified example 2, partial discharge of the heat conductive member 453 is prevented, noise generation is suppressed, and the insulation reliability of the insulating sheets 440 and 441 is maintained. Even if the resin insulating layer 443 in the conductive connection part 460 deteriorates, it does not affect the insulation or heat dissipation.

[0060] Figures 12(a), 12(b), 12(c), and 12(d) are semi-transparent plan views of the semiconductor device 300 showing modified examples 3 to 6 of this embodiment. Figure 12(a) shows modified example 3, Figure 12(b) shows modified example 4, Figure 12(c) shows modified example 5, and Figure 12(d) shows modified example 6. All of these are simplified versions of the semi-transparent plan view shown in Figure 5, and the same reference numerals are used for the same parts, and their explanations are simplified.

[0061] In the modified example 3 shown in Figure 12(a), five conductive connection parts 460 are provided. Four of the conductive connection parts 460 are provided within the projection area 462 of the surface conductor layer 444 covered by a single insulating sheet, as shown in Figure 5, and in the area on the outer periphery of the projection area 461 of the adhesive portion of the resin insulating layer 443. Here, the projection area 461 of the adhesive portion of the resin insulating layer 443 is shown with a dotted line, and the heat conductive member 453 is shown with a gray fill. The remaining conductive connection part 460 is located in the central part sandwiched between the projection areas 461 of the adhesive portion of the resin insulating layer 443, and is provided outside the projection area 461 of the adhesive portion of the resin insulating layer 443. The conductive connection parts 460 include the examples shown in Modified Example 1 and Modified Example 2.

[0062] In this modified example 3 as well, when pressure is applied by the pressurizing mechanism 341, force is applied evenly to the conductive connection part 460, preventing partial discharge of the heat conductive member 453, suppressing noise generation, and maintaining the insulation reliability of the insulating sheets 440 and 441. Even if the resin insulating layer 443 in the conductive connection part 460 deteriorates, it does not affect the insulation or heat dissipation.

[0063] In Modification 4 shown in Figure 12(b), terminals 325E and the like, which are connected to semiconductor elements, are led out from at least one side of the semiconductor device 300, but a heat conductive member 453 is provided on the shortest distance between the conductive connection part 460 and the terminal 325E. This heat conductive member 453 can be applied simultaneously in the coating process shown in Figure 8(a). In the conductive connection part 460, including the examples shown in Modification 1 and Modification 2, foreign matter (scraped powder) may be generated at the connection point due to friction caused by repeated thermal cycles. According to Modification 4, it is possible to prevent the generated foreign matter from adhering near the terminal and causing a short circuit.

[0064] In the modified example 5 shown in Figure 12(c), a resin member 454 is provided at the shortest distance between the conductive connection part 460 and the terminal 325E. The resin member 454 is made of a different resin material than the heat conductive member 453. In addition, a shielding member that shields the conductive connection part 460 and the terminal 325E may be used, not limited to a resin material. The material type of the shielding member is not specified. According to modified example 5, it is possible to prevent foreign matter generated at the connection point of the conductive connection part 460 from adhering to the vicinity of the terminal and causing a short circuit. In the modified example 6 shown in Figure 12(d), the heat conductive member 453 is provided in a region excluding the conductive connection portion 460, including the region along the shortest distance between the conductive connection portion 460 and the terminal 325E. In the coating process shown in Figure 8(a), the heat conductive member 453 is not applied near the conductive connection portion 460 to prevent it from adhering to the conductive connection portion 460. According to modified example 6, it is possible to prevent foreign matter from adhering near the terminal and causing a short circuit.

[0065] Figure 13 is a circuit diagram of a power converter 200 using a semiconductor device 300. The power converter 200 comprises inverter circuit sections 140 and 142, an auxiliary inverter circuit section 43, and a capacitor module 500. The inverter circuit sections 140 and 142 each contain multiple semiconductor devices 300, which are connected to form a three-phase bridge circuit. When the current capacity is large, the semiconductor devices 300 can be further connected in parallel, and these parallel connections can be made corresponding to each phase of the three-phase inverter circuit to accommodate the increased current capacity. In addition, the current capacity can be increased by connecting in parallel the semiconductor elements 155 and 157 and diodes 156 and 158, which are semiconductor elements built into the semiconductor devices 300.

[0066] Inverter circuit section 140 and inverter circuit section 142 have the same basic circuit configuration, and their control methods and operations are also basically the same. Since the general outline of the circuit operation of inverter circuit section 140, etc., is well known, a detailed explanation will be omitted here.

[0067] The upper arm circuit includes an active element 155 and an upper arm diode 156 as switching semiconductor elements, while the lower arm circuit includes an active element 157 and a lower arm diode 158 as switching semiconductor elements. The active elements 155 and 157 receive drive signals output from one or the other of the two driver circuits constituting the driver circuit 174 and perform switching operations to convert the DC power supplied from the battery 136 into three-phase AC power.

[0068] The active element 155 for the upper arm and the active element 157 for the lower arm are equipped with a collector electrode, an emitter electrode, and a gate electrode. The diode 156 for the upper arm and the diode 158 for the lower arm are equipped with two electrodes: a cathode electrode and an anode electrode. As shown in Figure 6, the cathode electrodes of diodes 156 and 158 are electrically connected to the collector electrodes of active elements 155 and 157, and the anode electrodes are electrically connected to the emitter electrodes of active elements 155 and 157. As a result, the current flow from the emitter electrode to the collector electrode of the active element 155 for the upper arm and the active element 157 for the lower arm is in the forward direction. The active elements 155 and 157 are, for example, IGBTs.

[0069] Alternatively, a MOSFET (metal oxide semiconductor field-effect transistor) may be used as the active element; in this case, the diode 156 for the upper arm and the diode 158 for the lower arm are not required.

[0070] The positive terminal 315B and negative terminal 319B of each upper and lower arm series circuit are connected to the DC terminals for capacitor connection of the capacitor module 500, respectively. AC power is generated at the connection points of the upper and lower arm circuits, and the connection points of the upper and lower arm circuits of each upper and lower arm series circuit are connected to the AC terminals 320B of each semiconductor device 300. The AC terminals 320B of each semiconductor device 300 for each phase are connected to the AC output terminals of the power converter 200, and the generated AC power is supplied to the stator windings of the motor generator 192 or 194.

[0071] The control circuit 172 generates timing signals to control the switching timing of the active element 155 for the upper arm and the active element 157 for the lower arm based on input information from the vehicle's control device and sensors (e.g., current sensor 180). The driver circuit 174 generates drive signals to switch the active element 155 for the upper arm and the active element 157 for the lower arm based on the timing signals output from the control circuit 172. Note that 181, 182, and 188 are connectors.

[0072] The upper and lower arm series circuit includes a temperature sensor (not shown), and temperature information from the upper and lower arm series circuit is input to the microcontroller. The microcontroller is also input voltage information from the DC positive terminal side of the upper and lower arm series circuit. Based on this information, the microcontroller performs over-temperature detection and over-voltage detection. If over-temperature or over-voltage is detected, the microcontroller stops the switching operation of all active elements 155 for the upper arm and 157 for the lower arm, protecting the upper and lower arm series circuit from over-temperature or over-voltage.

[0073] Figure 14 is an external perspective view of the power converter 200 shown in Figure 13, and Figure 15 is a cross-sectional perspective view of the power converter 200 shown in Figure 14 along the line XV-XV.

[0074] The power converter 200 is comprised of a lower case 11 and an upper case 10, and has a housing 12 formed in a substantially rectangular parallelepiped shape. Inside the housing 12 are an electrical circuit 400, a capacitor module 500, and the like. The electrical circuit 400 has a cooling channel through which water flows to a cooling member 340, and a cooling water inlet pipe 13 and a cooling water outlet pipe 14, which communicate with the cooling channel, protrude from one side of the housing 12. The upper side of the lower case 11 is open, 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 from an aluminum alloy or the like and are sealed and fixed to the outside. The upper case 10 and the lower case 11 may be configured as a single unit. The housing 12 has a simple rectangular parallelepiped shape, which makes it easy to attach to vehicles and the like, and also makes it easier to manufacture.

[0075] A connector 17 is attached to one longitudinal side of the housing 12, and an AC terminal 18 is connected to this connector 17. In addition, a connector 21 is provided on the side from which the cooling water inlet pipe 13 and cooling water outlet pipe 14 are routed.

[0076] As shown in Figure 15, an electrical circuit 400 is housed inside the housing 12. A control circuit 172 and a driver circuit 174 are located above the electrical circuit 400, and a capacitor module 500 is housed on the DC terminal side of the electrical circuit 400. By positioning the capacitor module at the same height as the electrical circuit 400, the power converter 200 can be made thinner, improving the flexibility of installation in the vehicle. The AC terminal 320B of the electrical circuit 400 is connected to the connector 188, passing through the current sensor 180. In addition, the DC terminals of the semiconductor device 300, the positive terminal 315B and the negative terminal 319B, are connected to the positive and negative terminals 362A and 362B of the capacitor module 500, respectively.

[0077] According to the embodiments described above, the following effects and advantages can be obtained. (1) The electrical circuit body 400 comprises a semiconductor device 300 formed by integrally sealing semiconductor elements 155, 156, 157, 158, conductor plates 430, 431, 432, 433 to which the semiconductor elements 155, 156, 157, 158 are joined, and insulating sheets 440, 441 adhered to the heat dissipation surfaces of the conductor plates 430, 431, 432, 433 with a sealing material 360; a cooling member 340 positioned opposite the semiconductor device 300 to cool the heat generated by the semiconductor elements 155, 156, 157, 158; and a heat conductive member 453 positioned between the insulating sheets 440, 441 and the cooling member 340. The insulating sheets 40 and 441 are provided with a resin insulating layer 443 that covers the conductor plates 430, 431, 432, and 433 on one side and is bonded to the heat dissipation surface of the conductor plates 430, 431, 432, and 433, and a surface conductor layer 444 that is bonded to the other side of the resin insulating layer 443 and is exposed on the surface of the semiconductor device 300. A conductive connection portion 460 is formed in the projection area of ​​the surface conductor layer 444 and in the area on the outer periphery side of the bonding area 461 between the conductor plates 430, 431, 432, and 433 and the resin insulating layer 443, electrically connecting the surface conductor layer 444 and the cooling member 340 to each other. This improves the insulating reliability of the insulating sheet.

[0078] The present invention is not limited to the embodiments described above, and other forms 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 features of the present invention. Furthermore, the above embodiments may be combined with multiple modifications. [Explanation of symbols]

[0079] 10...Upper case, 11...Lower case, 13...Cooling water inlet pipe, 14...Cooling water outlet pipe, 17...Connector, 18...AC terminal, 43, 140, 142...Inverter circuit, 155, 156, 157, 158...Semiconductor element, 172...Control circuit, 174...Driver circuit, 180...Current sensor, 21, 181, 182, 188...Connector, 192, 194...Motor generator, 200...Power converter, 300...Semiconductor device, 315B...Positive terminal, 319B...Negative terminal, 320B...AC terminal, 325U...Upper arm gate terminal 325U, 325L...Lower arm gate terminal, 325E ...Emitter sense terminal, 325C...Collector sense terminal, 340...Cooling material, 341...Pressurizing mechanism, 360...Sealing material, 400...Electrical circuit body, 420, 430, 431, 432, 433...Conducting plate, 440, 441...Insulating sheet, 443...Resin insulating layer, 444...Surface conductor layer, 445...Intermediate conductor layer, 453...Heat conductive material, 454...Resin material, 457...Void, 460...Conductive connection part, 461...Projection area of ​​adhesive part of resin insulating layer, 462...Projection area of ​​surface conductor layer, 447...High thermal conductivity filler, 500...Capacitor module, 601...Transfer molding device, 602...Spring.

Claims

1. A semiconductor device comprising a semiconductor element, a conductive plate to which the semiconductor element is bonded, and an insulating sheet adhered to the heat dissipation surface of the conductive plate, all integrally sealed with a sealing material, A cooling member is positioned opposite the semiconductor device and cools the heat generated by the semiconductor element, The system comprises a heat conductive member disposed between the insulating sheet and the cooling member, The insulating sheet has a resin insulating layer that covers the conductor plate on one side and is adhered to the heat dissipation surface of the conductor plate, and a surface conductor layer that is adhered to the other side of the resin insulating layer and is exposed on the surface of the semiconductor device, and a conductive connection portion is formed in the projection region of the surface conductor layer and the region on the outer periphery of the adhesion region between the conductor plate and the resin insulating layer, electrically connecting the surface conductor layer and the cooling member to each other.

2. In the electrical circuit described in claim 1, The conductive connection portion is an electrical circuit body in which a protrusion facing the cooling member is provided on the sealing material, and the surface conductor layer of the insulating sheet is connected to the cooling member by the protrusion.

3. In the electrical circuit described in claim 1, The conductive connection portion is an electrical circuit body in which a protrusion facing the semiconductor device is provided on the cooling member, and the cooling member is connected to the surface conductor layer of the insulating sheet by the protrusion.

4. In the electrical circuit described in claim 1, The conductive connection portion is an electrical circuit body configured by providing a conductive member between the semiconductor device and the cooling member, and connecting the cooling member and the surface conductor layer of the insulating sheet via the conductive member.

5. In the electrical circuit described in claim 1, The insulating sheet is an electrical circuit body having a conductive intermediate conductor layer embedded in the resin insulating layer.

6. In the electrical circuit described in claim 1, The conductive connection portion is an electrical circuit body that is arranged symmetrically on either side of the adhesive region of the resin insulating layer in a planar direction intersecting the stacking direction of the semiconductor device and the cooling member.

7. In the electrical circuit body according to any one of claims 1 to 6, A terminal connected to the semiconductor element is derived from at least one side of the semiconductor device. An electrical circuit body in which a blocking member is provided at the shortest distance between the conductive connection portion and the terminal.

8. In the electrical circuit body according to any one of claims 1 to 6, The semiconductor device has the conductive plate and the insulating sheet formed on both sides of the semiconductor element. The cooling member is arranged on both sides of the semiconductor device via the heat conductive member. The conductive connection portion is an electrical circuit body located on both sides between the semiconductor device and the cooling member, and is arranged symmetrically in the stacking direction of the semiconductor device and the cooling member.

9. A power conversion device comprising an electrical circuit body according to any one of claims 1 to 6, which converts DC power to AC power.

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