Semiconductor device and power conversion device

Abstract

To solve the problem in which: the reliability of a semiconductor device deteriorates due to displacement caused by vibration and a heat cycle.SOLUTION: A semiconductor device includes a plurality of electrical circuit bodies having semiconductor elements, a pair of heat radiating members sandwiching the plurality of electric circuit bodies from both sides thereof, a first thermally conductive member arranged between one of the heat radiating members and one of surfaces of the plurality of electric circuit bodies, and a second thermally conductive member arranged between the other of the heat radiating members and the other surfaces of the plurality of electric circuit bodies, and the elongation until peeling of the first thermally conductive member is greater than the elongation until peeling of the second thermally conductive member.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] A power conversion device that switches a power semiconductor element is widely used in consumer, in-vehicle, railway, and substation equipment because of its high conversion efficiency. Since this power semiconductor element generates heat when energized, a heat dissipation member is provided in a semiconductor device incorporating the power semiconductor element.

[0003] Patent Document 1 discloses a semiconductor device in which a heat dissipation material (heat conduction member) is provided between the semiconductor device and the heat dissipation member, and heat is conducted to the heat dissipation member through the heat dissipation material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology disclosed in Patent Document 1, there is a problem that the reliability of the semiconductor device decreases with respect to displacement caused by vibration or a thermal cycle.

Means for Solving the Problems

[0006] The semiconductor device according to the present invention includes a plurality of electric circuit bodies having semiconductor elements, a pair of heat dissipation members that sandwich the plurality of electric circuit bodies from both sides thereof, a first heat conduction member disposed between one of the heat dissipation members and one surface of the plurality of electric circuit bodies, and a second heat conduction member disposed between the other of the heat dissipation members and the other surface of the plurality of electric circuit bodies, and an elongation until peeling of the first heat conduction member has an elongation larger than an elongation until peeling of the second heat conduction member.

Advantages of the Invention

[0007] According to the present invention, the reliability of the semiconductor device is improved against displacements caused by vibrations and thermal cycles.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

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, omissions and simplifications are made as appropriate. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In the drawings, the positions, sizes, shapes, ranges, etc. of the respective components shown may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. For this reason, 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 the semiconductor device 400. The semiconductor device 400 includes a plurality of electric circuit bodies 300, a heat radiating member 340, and heat conduction members 453 and 454, which will be described later. In FIG. 1, as an example, a semiconductor device 400 including electric circuit bodies 300 for three modules is shown.

[0012] The electric circuit body 300 incorporates a power semiconductor element and switches the power semiconductor element to convert a direct current and an alternating current, but generates heat due to the switching operation. The heat radiating member 340 cools the heated electric circuit body 300, and a refrigerant is circulated inside the heat radiating member 340 for cooling. As the refrigerant, water or an antifreeze obtained by mixing ethylene glycol with water is used. Although the details of the heat conduction members 453 and 454 will be described later, the heat conduction members 453 and 454 are disposed between the heat radiating member 340 and the electric circuit body 300.

[0013] The semiconductor device 400 includes a pressing member 370 that presses the electric circuit bodies 300 for three modules from both sides. The pressing member 370 abuts on and sandwiches the outer surfaces of a pair of heat radiating members 340 and 350 (see FIG. 3) to press the heat conduction members 453 and 454. The pressing member 370 is, for example, a leaf spring or a clip formed in a U shape, and any member having a pressing elastic force in the sandwiching direction may be used.

[0014] The electric circuit body 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. 13) of a DC circuit, and an AC terminal 320B connected to motor generators 192 and 194 (see FIG. 13) of an AC circuit. Further, it includes signal terminals used for controlling a semiconductor device, such as a lower arm gate terminal 325L, a mirror emitter signal terminal 325M, a Kelvin emitter signal terminal 325K, an upper arm gate terminal 325U, a mirror emitter signal terminal 325M, and a Kelvin emitter signal terminal 325K, which are derived from a power semiconductor element.

[0015] FIG. 2 is a cross-sectional view taken along line X-X shown in FIG. 1 of the semiconductor device 400 shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line Y-Y shown in FIG. 1 of the semiconductor device 400 shown in FIG. 1.

[0016] As the first power semiconductor element forming the upper arm circuit, an active element 155 and a diode 156 are provided. As the active element, Si, SiC, GaN, GaO, C, etc. can be used. When using the body diode of the active element, a separately attached diode may be omitted. The collector sides of the first power semiconductor elements 155 and 156 are joined to the second conductor plate 431. For this joining, solder or sintered metal may be used. Also, the conductor plate is not particularly limited as long as it is a material with high electrical conductivity and high thermal conductivity, but a copper-based or aluminum-based material is desirable. These may be used alone, or may be plated with Ni, Ag, etc. to enhance the joinability with solder or sintered metal. The first conductor plate 430 is joined to the emitter sides of the first power semiconductor elements 155 and 156. The first conductor plate 430 has a recess on the outer periphery of the region connected to the power semiconductor element to ensure an insulation distance.

[0017] As the second power semiconductor element forming the lower arm circuit, an active element 157 and a diode 158 are provided. The collector sides of the second power semiconductor elements 157 and 158 are joined to the fourth conductor plate 433. The third conductor plate 432 is joined to the emitter sides of the second power semiconductor elements 157 and 158.

[0018] The conductor plates 430, 431, 432, and 433, in addition to serving to conduct current, also serve as heat transfer members that transfer the heat generated by the power semiconductor elements 155, 156, 157, and 158 to the heat dissipation member 340 on the emitter side and the heat dissipation member 350 on the collector side. Since the potential of the conductor plates 430, 431, 432, 433 and the heat dissipation members 340, 350 are different, the sheet-like members 440, 441 having resin insulating layers 442, 443 are interposed therebetween. Thermal conductive members 453, 454 are provided between the sheet-like members 440, 441 and the heat dissipation members 340, 350 to reduce the contact thermal resistance. The power semiconductor elements 155, 156, 157, 158, the conductor plates 430, 431, 432, 433, and the sheet-like members 440, 441 are encapsulated by the encapsulating member 360 by transfer molding.

[0019] The resin insulating layers 442, 443 of the sheet-like members 440, 441 are not particularly limited as long as they have adhesiveness to the conductor plates 430, 431, 432, 433, but an epoxy resin-based resin insulating layer in which a powdery inorganic filler is dispersed is desirable. This is because the balance between adhesiveness and heat dissipation is good. The sheet-like members 440, 441 may be a single resin insulating layer, but it is desirable to provide a metal foil 444 on the side in contact with the thermal conductive members 453, 454. When mounting the sheet-like members 440, 441 on the mold in the transfer molding process, in order to prevent adhesion to the mold, a release sheet or the metal foil 444 is provided on the contact surface of the sheet-like members 440, 441 with the mold. Since the release sheet has poor thermal conductivity, a step of peeling it off after transfer molding is required. In the case of the metal foil, by selecting a metal with high thermal conductivity such as copper-based or aluminum-based, it can be used without peeling off after transfer molding. By performing transfer molding including the sheet-like members 440, 441, the ends of the sheet-like members 440, 441 are covered by the encapsulating member 360, so there is an effect of improving reliability.

[0020] Figure 4 is a cross-sectional perspective view of the electric circuit body 300. A margin portion 451 that forms a step and protrudes is provided with respect to a buried portion 452 in which the ends of the sheet-like members 440 and 441 are covered by the sealing member 360. This has the effect of preventing the sealing member 360 and resin burrs made of the resin component of the sealing member 360 from flowing between the sheet-like members 440 and 441 and the mold. The sheet-like members 440 and 441 are vacuum-sucked to the transfer mold, but the suction force is much smaller than the molding pressure for injecting the transfer mold resin.

[0021] Also, when the inside of the cavity for injecting the sealing member 360 is evacuated for vacuum molding, the suction force becomes even weaker. For this reason, between the sheet-like members 440 and 441 and the transfer mold, the sealing member 360 and resin burrs made of the resin component in the sealing member 360 flow in from the outer peripheral portions of the sheet-like members 440 and 441. At this time, if the mold is processed so that a step is formed by the protruding margin portion 451 slightly inside the outer peripheral portions of the sheet-like members 440 and 441, the sealing member 360 and the resin burrs stop at this step.

[0022] Figs. 5(a) to 5(c) and Figs. 6(d) to 6(f) are cross-sectional views for explaining the manufacturing process of the semiconductor device 400. The X-X cross-section for one module is shown on the left side of each figure, and the Y-Y cross-section is shown on the right side.

[0023] Fig. 5(a) shows the soldering process and the wire bonding process. The collector sides of the power semiconductor elements 155, 156, 157, and 158 such as active elements and diodes are connected to the conductor plates 430, 431, 432, and 433, and the mirror emitter electrode of the active element is connected to the mirror emitter signal terminal 325M by wire bonding.

[0024] Figure 5(b) shows the transfer molding process. The transfer molding apparatus 601 includes a mechanism for vacuum-sucking the sheet-like members 440 and 441 onto the mold and a vacuum degassing mechanism. The sheet-like members 440 and 441 are placed in the mold that has been preheated to a constant temperature of 175°C in advance and held by vacuum suction. Then, the electric circuit body 300 that has been preheated to 175°C in advance is set in the mold while being separated from the sheet-like members 440 and 441. Next, at a position where the sheet-like members 440 and 441 do not contact the electric circuit body 300, the upper and lower molds are pressed so that only the packing installed in the upper and lower molds (not shown) comes into contact. Next, the inside of the mold cavity is evacuated. When the evacuation is completed so that the pressure becomes below a predetermined pressure, the packing is further crushed and the upper and lower molds are completely clamped. At this time, the sheet-like members 440 and 441 come into contact with the electric circuit body 300. In a vacuum state, since the sheet-like members 440 and 441 come into contact with the electric circuit body 300 and are adhered by the pressing force of the spring 602 of the transfer molding apparatus 601, they can be adhered without entrapping voids.

[0025] Figure 5(c) shows the encapsulation process. The encapsulating member 360 is injected into the mold cavity to encapsulate the electric circuit body 300. Figure 6(d) is a view showing the state where the encapsulated electric circuit body 300 is taken out. A step is formed between the buried portion 452 and the margin portion 451. No step is formed between the heat dissipation surface portion 450 and the margin portion 451.

[0026] Figure 6(e) shows the process of installing the heat conduction members 453 and 454 and the heat dissipation members 340 and 350 on the electric circuit body 300. The semiconductor device 400 is manufactured by pressing the heat dissipation members 340 and 350 against both sides of the electric circuit body 300 via the heat conduction members 453 and 454. Figure 6(f) is a cross-sectional view of the semiconductor device 400. It shows the semiconductor device 400 manufactured through the above processes.

[0027] Hereinafter, with reference to Figure 6(f), the heat conduction members 453 and 454 in the present embodiment will be described. First, it is desirable that the heat dissipation members 340 on the emitter side and 350 on the collector side be made of an aluminum-based material with high thermal conductivity and low weight. The heat dissipation members 340 and 350 are manufactured by extrusion molding, forging, brazing, or the like. Also, from the perspective of heat dissipation, it is desirable that the widths of the heat dissipation members 340 and 350 be wider than the widths of the sheet-like members 440 and 441.

[0028] The heat conduction members 453 and 454 are not particularly limited as long as they are made of a material with high thermal conductivity. However, it is preferable to use a combination of a high thermal conductivity material such as a metal, ceramics, or carbon-based material with a resin material. This is because the resin material fills the gaps between the high thermal conductivity materials, between the high thermal conductivity materials and the heat dissipation members 340 and 350, and between the high thermal conductivity members and the sheet-like members 440 and 441, reducing the contact thermal resistance. The resin material is not particularly limited. For example, a material with good electrical insulation properties mainly composed of a silicone-based resin is preferable.

[0029] The thermal conductivity of the heat conduction members 453 and 454 is about 5 to 8 W / m·K. The method for measuring the thermal conductivity is not particularly limited. For example, it can be obtained by measuring the density, specific gravity, and thermal diffusivity of the heat conduction member and multiplying them together (density × specific gravity × thermal diffusivity).

[0030] The elongation until peeling of the heat conduction member 453 on the emitter side is greater than the elongation until peeling of the heat conduction member 454 on the collector side. The elongation of the heat conduction member 453 on the emitter side is 10 to 20%, and the elongation of the heat conduction member 454 on the collector side is 1 to 5%. The elongation is represented by the following formula (1). Elongation = (L - L0) / L × 100% ···(1)

[0031] Here, L0 represents the sample length before the test, and L represents the sample length at the time of breakage. The method for measuring the elongation is not particularly limited. For example, in accordance with JIS-C-2151, using a tensile tester, pulling at a speed of 200 mm / min, the strength (the value obtained by dividing the tensile load value by the cross-sectional area of the test piece) and the elongation when the test piece is cut (broken) can be obtained. That is, the elongation is the value obtained by dividing the elongation amount L - L0 between the gauge points of the broken test piece by the gauge distance L and expressing it as a percentage.

[0032] The adhesive strength of the heat conduction member 454 on the collector side is greater than that of the heat conduction member 453 on the emitter side. The adhesive strength of the heat conduction member 454 on the emitter side is 0 to 0.05 MPa, and the adhesive strength of the heat conduction member 453 on the collector side is 0.2 to 20 MPa. The method for measuring the adhesive strength is not particularly limited. For example, in accordance with JIS K6852, a test piece with two adherends sandwiching a sample is made, and using a shear tester, the maximum load until the test piece breaks is recorded, and the adhesive strength (MPa) is obtained by dividing the maximum load by the shear cross-sectional area.

[0033] Here, the relationship between the elongation and the adhesive strength will be described. The heat conduction members 453 and 454 tend to have a lower adhesive strength as their elongation increases. In other words, the elongation decreases as the adhesive strength increases. Therefore, when the elongation of the heat conduction member 453 on the emitter side is made greater than that of the heat conduction member 454 on the collector side, inevitably, the adhesive strength of the heat conduction member 454 on the collector side will be greater than that of the heat conduction member 453 on the emitter side. In this embodiment, an example was described in which the heat conduction member 453 on the emitter side is made of a material with a greater elongation than that of the heat conduction member 454 on the collector side, and the adhesive strength of the heat conduction member 454 on the collector side is made of a material with a greater adhesive strength than that of the heat conduction member 453 on the emitter side. However, from the above-described relationship between the elongation and the adhesive strength, at least the heat conduction member 453 on the emitter side may be made of a material with a greater elongation than that of the heat conduction member 454 on the collector side.

[0034] Then, the heat conduction member 453 with a large elongation is arranged on the emitter side, and the heat conduction member 454 with a small elongation is arranged on the collector side. The second conductor plate 431 and the fourth conductor plate 433 on the collector side are made by processing flat plates, and the first conductor plate 430 and the third conductor plate 432 on the emitter side have recesses on the outer periphery of the region connected to the power semiconductor elements 155 and 156 to ensure an insulation distance. For this reason, the conductor plates 431 and 433 on the collector side have high flatness and are used as reference surfaces during transfer molding or when assembling with the heat dissipation member. When a plurality of electric circuit bodies 300 are sandwiched between a pair of heat dissipation members 340 and 350, the thickness variation of the electric circuit bodies 300 is concentrated on the emitter side. By arranging the heat conduction member 453 with a higher elongation on the emitter side, the thickness variation between the electric circuit bodies 300 can be absorbed, thereby ensuring reliability and heat dissipation performance.

[0035] The average thickness of the heat conduction member 453 on the emitter side is larger than the average thickness of the heat conduction member 454 on the collector side. When a plurality of electric circuit bodies 300 are sandwiched between a pair of heat dissipation members 340 and 350, the average thickness of the heat conduction member 453 on the emitter side is obtained by dividing the sum of the thicknesses of the heat conduction member 453 applied to the emitter side of the plurality of electric circuit bodies 300 by the number of the electric circuit bodies 300. Similarly, the average thickness of the heat conduction member 454 on the collector side is obtained by dividing the sum of the thicknesses of the heat conduction member 454 applied to the collector side of the plurality of electric circuit bodies 300 by the number of the electric circuit bodies 300. Note that the thicknesses of the heat conduction members 453 and 454 are the thicknesses of the portions where the heat conduction members 453 and 454 overlap with the conductor plates 430, 431, 432, and 433. In other words, the thickness of the heat conduction member 453 is the thickness of the heat conduction member 453 on the projection plane of the conductor plate 430, and the thickness of the heat conduction member 454 is the thickness of the heat conduction member 454 on the projection plane of the conductor plate 431.

[0036] The pressing member 370 (see FIG. 3) abuts on and sandwiches the outer surfaces of the pair of heat dissipation members 340 and 350, pressing the heat conduction members 453 and 454. Thereby, the heat conduction member 454 can be brought into close contact with the electric circuit body 300 and the heat dissipation member 340, having the effect of ensuring heat dissipation performance and reliability.

[0037] FIG. 7 is a cross-sectional view of the semiconductor device in Comparative Example 1. FIG. 8 is a cross-sectional view of the semiconductor device in Comparative Example 2. These Comparative Examples 1 and 2 are shown for comparing an example of the case where the present embodiment is not applied with the present embodiment.

[0038] Comparative Example 1 shown in FIG. 7 is an example in which heat conduction members 453 having a large elongation are disposed on both surfaces of the electric circuit body 300. In this case, when vibration is applied to the semiconductor device, since the elongation of the heat conduction members 453 disposed on both surfaces is large, it is difficult to fix the electric circuit body 300, and the electric circuit body 300 easily moves in the direction in which the electric circuit bodies 300 are arranged, and the reliability of the semiconductor device such as peeling of the heat conduction members 453 is lowered.

[0039] On the other hand, in the present embodiment, the heat conduction member 453 having a large elongation is disposed on the emitter side, and the heat conduction member 454 having a small elongation is disposed on the collector side. Thereby, the movement of the electric circuit body 300 can be moderately suppressed, and the reliability of the semiconductor device can be enhanced.

[0040] Comparative Example 2 shown in FIG. 8 is an example in which heat conduction members 454 having a large adhesive strength are disposed on both surfaces of the electric circuit body 300. In this case, due to the heat cycle applied by the electric circuit body 300, it is difficult for the heat conduction member 454 to follow the displacement caused by the thermal expansion and thermal contraction with the sheet-like members 440 and 441 having different coefficients of thermal expansion, and the reliability of the semiconductor device such as peeling of the heat conduction member 454 and the sheet-like members 440 and 441 is lowered.

[0041] On the other hand, in the present embodiment, the heat conduction member 454 having a large adhesive strength is disposed on the collector side, and the heat conduction member 454 having a small adhesive strength is disposed on the emitter side. Thereby, the heat conduction member 454 can moderately follow the displacement due to the heat cycle of the electric circuit body 300, and the reliability of the semiconductor device can be enhanced.

[0042] FIG. 9 is a cross-sectional view of Modification 1 of the semiconductor device 400. This figure represents a cross-sectional view similar to the X-X cross-section shown on the left side of FIG. 6(f).

[0043] As shown in FIG. 9, a recess 455 is formed in a sealing member 360 which is on the outer peripheral side of a sheet-like member 440 on the emitter side. A heat conductive member 453 is disposed on the emitter side of the electric circuit body 300, and a heat conductive member 454 is disposed on the collector side of the electric circuit body 300. During a heat cycle, since the heat conductive member 453 interposed between the electric circuit body 300 and the heat radiating member 340 on the emitter side has a large elongation, there is a concern that it may protrude to the outer peripheral side. For high heat dissipation, the heat conductive member 453 is often highly filled with conductive fillers such as metal and carbon. If it protrudes to the outer peripheral side and drips onto the terminals, there is a concern that the insulation with the conductor layer connected to the terminals may be deteriorated due to reactions such as migration. By forming the recess 455 in the sealing member 360, the recess 455 serves as a reservoir chamber for the heat conductive member 453, so that it is difficult for the heat conductive member 453 to protrude to the outer peripheral side, and there is an effect of excellent insulation.

[0044] The method of forming the recess 455 is not limited. For example, by providing a protrusion on the mold in the transfer molding process, the recess 455 is formed at the end of the sealing member 360. This recess 455 is formed along the outer edge of the sheet-like member 440. The sheet-like member 440 has a heat radiating surface portion 450 (see FIG. 4) overlapping the conductor plates 430 and 432, and conducts heat to the heat radiating member 340 through the heat conductive member 453. It is desirable that the shape of the recess 455 is such that the bottom width is shorter than the opening surface width. This is because it is easy to provide a protrusion with an inclined side surface on the mold, and no post-processing such as machining is required after forming by the mold. Also, it is desirable that the height of the recess 455 on the sheet-like member 440 side is higher than the height of the end portion side of the sealing member 360. This is because when the width of the heat radiating member 340 becomes long for heat dissipation or when the end portion of the sealing member 360 warps in the direction of the heat radiating member 340 during a heat cycle, the end portion of the sealing member 360 does not collide with the heat radiating member 340, resulting in a highly reliable structure.

[0045] FIG. 10 is a cross-sectional view of a modification 2 of the semiconductor device 400. This figure shows a cross-sectional view similar to the X-X cross-section shown on the left side of FIG. 6(f).

[0046] As shown in FIG. 10, in addition to the recess 455 being formed in the sealing member 360 on the outer peripheral side of the sheet-like member 440, a recess 456 is provided in the heat dissipation member 340 on the emitter side so as to face the recess 455. The recess 456 of the heat dissipation member 340 is outside the sheet-like member 440. Similar to Modification 1, when the heat conduction member 453 protrudes, the volume of the recess for receiving the heat conduction member 453 increases, and the effect of preventing protrusion is enhanced.

[0047] The method and shape for providing the recess 456 in the heat dissipation member 340 are not particularly limited. And the recess may be formed in at least one of the sealing member 360 and the heat dissipation member 340 corresponding to the end of the heat conduction member 453 on the emitter side.

[0048] FIG. 11 is a semi-transparent plan view of the semiconductor device 400. FIG. 12 is a circuit diagram of the semiconductor device 400.

[0049] As shown in FIGS. 11 and 12, 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 and emitter sense 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 GND. The lower arm gate terminal 325L outputs from the gate and emitter sense of the active element 157 of the lower arm circuit. The AC side 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 instead of GND.

[0050] Also, conductor plates (upper arm circuit emitter side) 430 and conductor plates (upper arm circuit collector side) 431 are arranged above and below the active element 155 and the 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 the active element 157 and the diode 158 of the power semiconductor element (lower arm circuit).

[0051] The semiconductor device 400 of this embodiment has a 2in1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into one module. In addition, 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 400 can be reduced and the size can be reduced.

[0052] FIG. 13 is a circuit diagram of the power conversion device 200 using the semiconductor device 400. The power conversion device 200 includes inverter circuit units 140 and 142, an inverter circuit unit 43 for auxiliary equipment, and a capacitor module 500. The inverter circuit units 140 and 142 are composed of the semiconductor device 400 including a plurality of electric circuit bodies 300, and a three-phase bridge circuit is formed by connecting them. That is, the power conversion device 200 includes the semiconductor device 400 and converts DC power into AC power. When the current capacity is large, the semiconductor devices 400 are further connected in parallel, and these parallel connections are performed corresponding to each phase of the three-phase inverter circuit, so that an increase in current capacity can be accommodated. Also, an increase in current capacity can be accommodated by connecting in parallel the active elements 155 and 157 and the diodes 156 and 158 which are power semiconductor elements built in the electric circuit body 300.

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

[0054] As described above, the upper arm circuit includes an active element 155 for the upper arm and a diode 156 for the upper arm as power semiconductor elements for switching, and the lower arm circuit includes an active element 157 for the lower arm and a diode 158 for the lower arm as power semiconductor elements for switching. The active elements 155 and 157 perform a switching operation in response to a drive signal output from one or the other of two driver circuits constituting the driver circuit 174, and convert the DC power supplied from the battery 136 into three-phase AC power.

[0055] As described above, the active element 155 for the upper arm and the active element 157 for the lower arm include 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 include two electrodes, a cathode electrode and an anode electrode. As shown in FIG. 3, the cathode electrodes of the diodes 156 and 158 are electrically connected to the collector electrodes of the IGBTs 155 and 157, respectively, and the anode electrodes are electrically connected to the emitter electrodes of the active elements 155 and 157. Thereby, the flow of current 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.

[0056] Note that a MOSFET (metal oxide semiconductor field effect transistor) may be used as the active element. In this case, the diodes 156 for the upper arm and 158 for the lower arm are not required.

[0057] The positive terminal 315B and the negative terminal 319B of each upper and lower arm series circuit are respectively connected to the DC terminals for capacitor connection of the capacitor module 500. AC power is generated at the connection part between the upper arm circuit and the lower arm circuit, and the connection part between the upper arm circuit and the lower arm circuit of each upper and lower arm series circuit is connected to the AC side terminal 320B of each electric circuit body 300. The AC side terminals 320B of each electric circuit body 300 of each phase are respectively connected to the AC output terminals of the power conversion device 200, and the generated AC power is supplied to the stator windings of the motor generator 192 or 194.

[0058] Based on the input information from vehicle-side control devices and sensors (such as current sensor 180), the control circuit 172 generates a timing signal for controlling the switching timing of the active element 155 for the upper arm and the active element 157 for the lower arm. Based on the timing signal output from the control circuit 172, the driver circuit 174 generates a drive signal for switching the active element 155 for the upper arm and the active element 157 for the lower arm. Note that 181, 182, and 188 are connectors.

[0059] The upper and lower arm series circuit includes a temperature sensor (not shown), and the temperature information of the upper and lower arm series circuit is input to the microcomputer. Also, the voltage information on the DC positive electrode side of the upper and lower arm series circuit is input to the microcomputer. The microcomputer performs over-temperature detection and over-voltage detection based on this information. When over-temperature or over-voltage is detected, it stops the switching operations of all the active elements 155 for the upper arm and the active elements 157 for the lower arm, protecting the upper and lower arm series circuit from over-temperature or over-voltage.

[0060] FIG. 14 is an external perspective view of the power conversion device 200, and FIG. 15 is a cross-sectional view taken along line XV-XV of the power conversion device shown in FIG. 14.

[0061] The power conversion device 200 is composed of a lower case 11 and an upper case 10, and includes a housing 12 formed in a substantially rectangular parallelepiped shape. Inside the housing 12, a semiconductor device 400, a capacitor module 500, etc. are accommodated. The semiconductor device 400 has a cooling flow path, and from one side surface of the housing 12, a cooling water inflow pipe 13 and a cooling water outflow pipe 14 communicating with the cooling flow path protrude. The upper case 10 and the lower case 11 are formed of 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 integrally configured. By making the housing 12 into a simple rectangular parallelepiped shape, it becomes easy to attach to a vehicle or the like, and it is also easy to produce.

[0062] 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. Further, a connector 21 is provided on the surface from which the cooling water inflow pipe 13 and the cooling water outflow pipe 14 are led out.

[0063] As shown in FIG. 15, a semiconductor device 400 is housed in the housing 12. Above the semiconductor device 400, a control circuit 172 and a driver circuit 174 are arranged, and a capacitor module 500 is housed on the DC terminal side of the semiconductor device 400. By arranging the capacitor module 500 at the same height as the semiconductor device 400, the power conversion device 200 can be made thinner, and the degree of freedom in installation on a vehicle is improved. The AC side terminal 320B of the semiconductor device 400 passes through the current sensor 180 and is joined to the bus bar 361. Further, the positive electrode side terminal 315B and the negative electrode side terminal 319B, which are the DC terminals of the semiconductor device 400, are joined to the positive and negative electrode terminals of the capacitor module 500, respectively.

[0064] According to the embodiment described above, the following operational effects can be obtained. (1) The semiconductor device 400 includes a plurality of electric circuit bodies 300 having power semiconductor elements 155, 156, 157, 158, a pair of heat dissipation members 340, 350 that sandwich the plurality of electric circuit bodies 300 from both sides, a first heat conduction member 453 disposed between one of the heat dissipation members 340, 350 and one surface of the plurality of electric circuit bodies 300, and a second heat conduction member 454 disposed between the other of the heat dissipation members 340, 350 and the other surface of the plurality of electric circuit bodies 300. The elongation until peeling of the first heat conduction member 453 has a greater elongation than the elongation until peeling of the second heat conduction member 454. Thereby, the reliability of the semiconductor device 400 is improved against displacements caused by vibration and thermal cycles.

[0065] The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the features of the present invention are not impaired. Also, a configuration combining the above-described embodiment and a plurality of modification examples may be used.

Description of Reference Numerals

[0066] 10 ··· upper case, 11 ··· lower case, 12 ··· housing, 13 ··· cooling water inlet pipe, 14 ··· cooling water outlet pipe, 17, 21, 181, 182, 188 ··· connectors, 18 ··· AC terminal, 43, 140, 142 ··· inverter circuit section, 155, 156, 157, 158 ··· power semiconductor elements, 172 ··· control circuit, 174 ··· driver circuit, 180 ··· current sensor, 192, 194 ··· motor generator, 200 ··· power conversion device, 300 ··· electric circuit body, 315B ··· positive terminal, 319B ··· negative 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, 350 ··· heat dissipation member, 360 ··· sealing member, 370 ··· pressurizing member, 400 ··· semiconductor device, 430, 431, 432, 433 ··· conductor plates, 440, 441 ··· sheet-like members, 442, 443 ··· resin insulation layers, 444 ··· metal foil, 450 ··· heat dissipation surface portion, 451 ··· margin portion, 452 ··· buried portion, 453, 454 ··· heat conduction members, 455 ··· recess of the sealing member, 456 ··· recess of the heat dissipation member, 500 ··· capacitor module, 601 ··· transfer molding device.

Claims

1. A semiconductor device comprising: a plurality of electric circuit bodies each having a semiconductor element; a pair of heat dissipation members sandwiching the plurality of electric circuit bodies from both sides thereof; a first heat conduction member disposed between one of the heat dissipation members and one surface of the plurality of electric circuit bodies; and a second heat conduction member disposed between the other of the heat dissipation members and the other surface of the plurality of electric circuit bodies, wherein the elongation of the first heat conduction member until peeling is larger than the elongation of the second heat conduction member until peeling.

2. The semiconductor device according to claim 1, wherein the adhesive strength of the second heat conduction member is larger than the adhesive strength of the first heat conduction member.

3. The semiconductor device according to claim 1, wherein the first heat conduction member is disposed on the emitter side of the semiconductor element, and the second heat conduction member is disposed on the collector side of the semiconductor element.

4. The semiconductor device according to claim 3, wherein the thickness of the first heat conduction member is larger than the thickness of the second heat conduction member.

5. The semiconductor device according to claim 1, wherein the elongation of the first heat conduction member is 10 to 20%, and the elongation of the second heat conduction member is 1 to 5%.

6. The semiconductor device according to claim 2, wherein the adhesive strength of the first heat conduction member is 0 to 0.05 MPa, and the adhesive strength of the second heat conduction member is 0.2 to 20 MPa.

7. The semiconductor device according to any one of claims 1 to 6, wherein the thermal conductivity of the first heat conduction member and the second heat conduction member is 5 to 8 W / m·K.

8. The semiconductor device according to any one of claims 1 to 6, wherein the electric circuit body is sealed with a sealing member, and a recess is formed in at least one of the sealing member and the heat dissipation member corresponding to an end portion of the first heat conduction member.

9. The semiconductor device according to any one of claims 1 to 6, further comprising a pressing member that sandwiches and presses the first heat conduction member and the second heat conduction member in contact with outer surfaces of the pair of heat dissipation members.

10. A power conversion device comprising the semiconductor device according to any one of claims 1 to 6, and converting DC power into AC power.

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