Semiconductor device, power conversion device, and method of manufacturing semiconductor device

Abstract

To provide a semiconductor device, a power conversion device, and a method for manufacturing the semiconductor device that achieve both heat dissipation and reliability.SOLUTION: A semiconductor device 300 includes a first conductor plate 430 having semiconductor elements 155 and 156 bonded to one surface thereof, a heat-conducting sheet 440 made of thermosetting resin in close contact with the other surface of the first conductor plate 430, and a sealing material 360 that mold-seals the first conductor plate 430 and the heat-conducting sheet 440. The first conductor plate 430 has an inclined portion 461 at the outer peripheral end of the other surface of the first conductor plate 430, and the heat-conducting sheet 440 is in close contact with at least a part of the inclined portion 461, and the thickness of the heat-conducting sheet 440 is such that the sheet end portion facing the inclined portion 461 is thicker than the sheet central portion facing the portion on the other surface of the conductive plate 431 that is more inward than the inclined portion 461.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Power converters are widely used in consumer applications, in-vehicle applications, railway applications, substation facilities, and the like, due to their high power conversion efficiency achieved by switching power semiconductor elements. Such power semiconductor elements generate heat when current is applied, so high heat dissipation is required. For example, power converters for in-vehicle applications employ highly efficient water-cooled cooling systems to reduce size and weight. Regarding such heat dissipation structures, for example, Patent Document 1 listed below discloses a configuration in which insulating resin is filled in and around the heat dissipation surface of a semiconductor device in a power converter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 037072 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 can improve the heat dissipation of a semiconductor device, but at the same time, it is necessary to improve reliability. [Means for solving the problem]

[0005] The semiconductor device and power conversion device comprise a conductor plate having a semiconductor element bonded to one side thereof, a heat-conducting sheet of thermosetting resin adhered to the other side of the conductor plate, and a sealing material that mold-seals the conductor plate and the heat-conducting sheet, wherein the conductor plate has an inclined portion at the outer peripheral end of the other side thereof, the heat-conducting sheet adheres to at least a portion of the inclined portion, and the thickness of the heat-conducting sheet is thicker at the sheet end facing the inclined portion than at the sheet center facing the portion of the other side of the conductor plate that is more inward than the inclined portion. In addition, as a method for manufacturing the above-mentioned semiconductor device, a method is adopted in which the thermally conductive sheet containing a thermally conductive filler is compressed under pressure to make it semi-hardened, the semi-hardened thermally conductive sheet is placed on the other side of the conductor plate, and the conductor plate and the thermally conductive sheet are heated while being pressed in the thickness direction with a predetermined pressure. [Effects of the Invention]

[0006] It is possible to provide a semiconductor device, a power conversion device, and a method for manufacturing a semiconductor device that achieve both heat dissipation and reliability. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of an electric circuit body according to an embodiment of the present invention. [Figure 2] FIG. XX cross-sectional view according to one embodiment of the present invention. [Figure 3] FIG. 2 is a YY cross-sectional view according to one embodiment of the present invention. [Figure 4] 1 is a cross-sectional perspective view of a semiconductor device according to an embodiment of the present invention; [Figure 5] 1 is a semi-transparent plan view of a semiconductor device according to an embodiment of the present invention; [Figure 6] 1 is an example of a circuit of a semiconductor device according to an embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. [Figure 9]1 is a cross-sectional view illustrating the principle of the invention according to an embodiment of the present invention; [Figure 10] 1 is a method for manufacturing an insulating sheet according to one embodiment of the present invention. [Figure 11] 10A to 10C are diagrams illustrating the effects of the present invention. [Figure 12] 1 is a circuit diagram of a power conversion device according to an embodiment of the present invention. [Figure 13] 1 is an external perspective view showing an example of a power conversion device according to an embodiment of the present invention; [Figure 14] 1 is a cross-sectional perspective view of a power conversion device taken along line XV-XV according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (Figs. 1 to 6) The electric circuit body 400 has at least one semiconductor device 300 and a cooling member 340. The semiconductor device 300 converts DC current and AC current using multiple semiconductor elements. The electric circuit body 400 generates heat when current is applied, so it is cooled by a refrigerant flowing in the cooling member 340. The refrigerant flowing in the cooling member 340 can be water or an antifreeze solution made by mixing ethylene glycol with water.

[0011] The semiconductor device 300 has multiple power terminals through which large currents flow, such as a positive terminal 315B and a negative terminal 319B connected to a capacitor module 500 (see FIG. 12, etc.) in the DC circuit, and an AC terminal 320B connected to a motor generator 192 (see FIG. 12) in the AC circuit. The semiconductor device 300 also has signal terminals used to control the semiconductor device 300, such as a lower arm gate terminal 325L, an upper arm gate terminal 325U, a Miller emitter signal terminal 325M, and a Kelvin emitter signal terminal 325K. FIG. 6 illustrates the circuit configuration of the semiconductor device 300 per phase. In addition to the signal terminals described above, the semiconductor device 300 also has a positive terminal 315B and a negative terminal 319B of the upper and lower arm series circuits, and a voltage detection terminal 325C for detecting the voltages of the semiconductor elements in the upper and lower arms.

[0012] Electric circuit body 400 includes active element 155 and diode 156 as first power semiconductor elements that form an upper arm circuit. The active element may be made of Si, SiC, GaN, GaO, C, or the like. When a body diode of the active element is used, the separately provided diode may be omitted.

[0013] The collector sides of the active element 155 and the diode 156 are bonded to one surface of the second conductor plate 431. The emitter sides of the active element 155 and the diode 156 are bonded to the first conductor plate 430. Solder or sintered metal may be used for this bonding. The conductor plate may be made of any material with high electrical and thermal conductivity, but copper-based or aluminum-based materials are preferable. These may be used alone, or may be plated with Ni, Ag, or the like to improve bonding with the solder or sintered metal.

[0014] The electric circuit 400 includes an active element 157 and a diode 158 as second power semiconductor elements that form a lower arm circuit. The collector sides of the active element 157 and the diode 158 are bonded to one surface of the fourth conductor plate 433 (FIG. 3). The emitter sides of the active element 157 and the diode 158 are bonded to the third conductor plate 432 (FIG. 3).

[0015] Each conductor plate may be equipped with a substrate equipped with circuit components to add functions such as a current sensor or lifespan diagnosis. In addition to carrying current, each conductor plate also serves as a heat transfer section that transfers heat generated by each power semiconductor element to the cooling member 340. Because each conductor plate and the cooling member 340 have different potentials, a thermally conductive sheet 440 is disposed between each conductor plate and the cooling member 340. The thermally conductive sheet 440 is made of a thermosetting resin having a resin insulating layer 442 and a metal foil 444. The thermally conductive sheet 440 is in close contact with the other side of each conductor plate opposite to the side where the power semiconductor element is bonded. Furthermore, the side of the thermally conductive sheet 440 opposite to the side that is in close contact with the conductor plate is in contact with the cooling member 340.

[0016] Each conductive plate has an inclined portion 461 at the outer peripheral end on the other surface to which the thermally conductive sheet 440 is in close contact. Also, on the same other surface, a flat portion 460 is formed on the inner peripheral side of the inclined portion 461.

[0017] If the portion of the thermally conductive sheet 440 facing the flat portion 460 is the sheet center portion, and the portion of the thermally conductive sheet 440 facing the inclined portion 461 is the sheet end portion, the thermally conductive sheet 440 is in close contact with at least a part of the inclined portion 461. The thickness of the thermally conductive sheet 440 is formed so that the sheet end portion facing the inclined portion 461 is thicker than the sheet center portion.

[0018] A heat conducting member 453 is provided between heat conducting sheet 440 and cooling member 340 to reduce contact thermal resistance. A resin member (not shown) is provided between heat conducting member 453 and cooling member 340. Each power semiconductor element, each conductor plate, and heat conducting sheet 440 are mold-sealed with sealing material 360 by transfer molding.

[0019] The resin insulating layer 442 of the thermally conductive sheet 440 has adhesive properties with the conductor plate. There are no particular limitations on the resin insulating layer 442 as long as it contains a volume expansion material, but in consideration of the balance between adhesiveness and heat dissipation, an epoxy resin-based resin insulating layer in which a highly thermally conductive inorganic filler is dispersed is desirable. The thermally conductive sheet 440 may be composed of the resin insulating layer 442 alone, but it is desirable to provide a metal foil 444 on the side that comes into contact with the thermally conductive member 453.

[0020] The thermally conductive sheet 440 is formed from a volume expansion material. The volume expansion material is not particularly limited as long as it expands in volume when heated during the transfer molding process or releases a volume expansion component. Therefore, the volume expansion material can be a microcapsule containing a vaporizable component, or an organic or inorganic material that generates gas when heated. Furthermore, from the perspectives of heat dissipation and insulation, it is particularly desirable to use air bubbles contained in the resin insulation layer 442 as the volume expansion material, rather than an additive. This is because, since it is not an additive, it has little effect on heat dissipation, and by reducing the size of the air bubbles, the effect on insulation can also be reduced.

[0021] Each conductor plate is preferably made of a material with high electrical and thermal conductivity, and may be made of a metal material such as copper or aluminum, or a composite material of a metal material and a highly thermally conductive material such as diamond, carbon, or ceramic. The cooling member 340 is preferably made of an aluminum material, which has high thermal conductivity and is lightweight. The cooling member 340 is manufactured by extrusion molding, forging, brazing, or the like.

[0022] To ensure workability and long-term reliability, the thermal conductive material 453 is preferably a curable thermal conductive material that has fluidity when uncured but loses fluidity after curing. Curable thermal conductive material 453 has low viscosity when applied, making it easy to work with, while also having the advantage of being able to improve mechanical properties by curing it later. Curing can be done using heat curing, moisture curing, ultraviolet curing, etc., but heat curing is preferable for deep curing.

[0023] Because the thermal conductive member 453 is in close contact between the semiconductor device 300 and the cooling member 340, which have different thermal expansion coefficients, a Young's modulus of 50 MPa or less is desirable to reduce stress. This Young's modulus is a value measured in a dynamic viscoelasticity test in the tensile or compressive direction at a frequency of 10 Hz, a strain of 0.1%, and a temperature of 25°C. The thermal conductive member 453 is a material made by mixing a highly thermally conductive material such as metal, ceramic, or carbon-based material with a resin. Silicone resin is most desirable as the resin, as its elastic modulus changes little over a temperature change from around -40°C to around 200°C.

[0024] (Manufacturing method) (Fig. 7, Fig. 8) A method for manufacturing a semiconductor device according to the present invention will be described with reference to Figures 7(a) to 7(d) and Figures 8(a) and 8(b). Figure 7(a) shows a temporary attachment process in which the thermally conductive sheet 440 is attached to each conductor plate using its adhesive strength, leaving room for the thermally conductive sheet 440 to harden and adhere during the transfer molding process. First, the collector side of a power semiconductor element such as an active element or diode is connected to each conductor plate, the gate electrode of the active element is connected by wire bonding, and the emitter side of the power semiconductor element is connected to another conductor plate. This completes the electrical circuit body 400, after which the thermally conductive sheet 440 is temporarily attached to each conductor plate.

[0025] 7(b) to 7(d) show the transfer molding process. Transfer molding apparatus 601 is equipped with a spring 602 in its mold. By providing spring 602, even if there is variation in the height of the semiconductor devices 300 installed in transfer molding apparatus 601, a predetermined load can be applied by the spring force without excessive compression to each power semiconductor element. Transfer molding apparatus 601 also has a vacuum degassing mechanism (not shown), which can compress even voids to a small size by vacuum degassing, thereby improving insulation. Note that transfer molding apparatus 601 can use a release film (not shown), which can protect the drive part of spring 602 from resin burrs.

[0026] In FIG. 7(b), the semiconductor device 300 with the thermally conductive sheet 440 temporarily attached as shown in FIG. 7(a) is placed in a mold preheated to a constant temperature of 175°C. When the thermally conductive sheet 440 is placed in the mold, a release sheet or metal foil 444 is provided on the contact surface of the thermally conductive sheet 440 with the mold to prevent it from adhering to the mold. Release sheets have poor thermal conductivity and require a peeling process after transfer molding. However, the metal foil 444 has the advantage of eliminating the peeling process after transfer molding by selecting a copper-based or aluminum-based metal with high thermal conductivity. By transfer molding the semiconductor device 300 including the thermally conductive sheet 440, the edges of the thermally conductive sheet 440 are covered with a sealant 360, improving the reliability of the semiconductor device 300.

[0027] In Figure 7(c), the upper and lower molds of transfer molding device 601 are clamped. Molding sealant 360 is set in the injection port of transfer molding device 601. At this time, spring 602 presses flat portion 460 of each conductor plate toward thermally conductive sheet 440 in the thickness direction with a predetermined pressure, and thermally conductive sheet 440 is also pressed toward flat portion 460 of each conductor plate, thereby bringing them into close contact with each other. At this time, flat portion 460 of each conductor plate and thermally conductive sheet 440 are in close contact with each other, but there is a gap between inclined portion 461 at the outer peripheral end of flat portion 460 and thermally conductive sheet 440, and they are not in close contact with each other.

[0028] In this state, when the semiconductor device 300 and the thermally conductive sheet 440 are heated within the mold of the transfer molding device 601, the volume expansion material incorporated in the thermally conductive sheet 440 expands, and the thermally conductive sheet 440 expands in the thickness direction. In this way, the thermally conductive sheet 440 and a part of the inclined portion 461, which were not in contact before heating, come into close contact with each other due to the expansion of the volume expansion portion of the thermally conductive sheet 440. Meanwhile, because the flat portion 460 of the thermally conductive sheet 440 is pressurized, the expansion of the thermally conductive sheet 440 is suppressed.

[0029] 7(d), sealing material 360 is injected into the mold of transfer molding device 601, and electric circuit body 400 is pressurized by the molding pressure of sealing material 360. If the pressing force due to this molding pressure is higher than the pressing force generated on flat portion 460, expansion of thermally conductive sheet 440 relative to inclined portion 461 will be suppressed. For this reason, it is desirable that the molding pressure of sealing material 360 be lower than the pressing force applied to flat portion 460 of the conductor plate. The semiconductor device 300 to which thermally conductive sheet 440 is attached, which has been resin-sealed with sealing material 360 and expanded, is removed from transfer molding device 601 and post-cured at a temperature of 175°C for two hours or more.

[0030] 8(a), a resin member (not shown) is applied to the heat conductive member 453, and the cooling member 340 is brought into close contact with the semiconductor device 300 via the heat conductive member 453. By hardening the heat conductive member 453 and the resin member, the electric circuit body 400 shown in FIG.

[0031] (Expansion process of the thermal conductive sheet) (Figure 9) 9(a) to 9(c) will be used to explain the expansion process of the thermally conductive sheet 440 during heating in the transfer molding process. Note that Fig. 9(a) is an enlarged view of dashed line A in Fig. 7(c), and Fig. 9(c) is an enlarged view of dashed line B shown in Fig. 7(d).

[0032] The conductor plate is made of a metal material to increase productivity, but when it is produced by press working, the gap between the punch of the upper mold and the die of the lower mold during punching creates an inclined surface due to sagging on the punch surface and burrs on the die surface. If the conductor plate comes into contact with the thermally conductive sheet 440 with burrs, there is a risk of insulation deterioration, so it is desirable that the surface of the conductor plate that comes into close contact with the thermally conductive sheet 440 be the sagging side or the burr side with the burrs chamfered.

[0033] The outer peripheral edge of the conductive plate is formed with an inclined portion 461. Because a highly thermally conductive thermally conductive material has a high elastic modulus even before hardening, it is hardly compressed even when pressure is applied. Therefore, if pressure is applied in this state, the thermally conductive sheet 440 will not adhere to the inclined portion 461, resulting in a problem of reduced heat dissipation. Therefore, in the present invention, the thermally conductive sheet 440 is expanded to adhere to the inclined portion 461, thereby improving heat dissipation.

[0034] 9(a), as described above, in the transfer molding process, the upper and lower molds heated to 175°C are clamped together, and the thermally conductive sheet 440 and the flat portion 460 of the conductor plate are pressed by the spring 602 to adhere to each other. On the other hand, there is a gap between the inclined portion 461 of the conductor plate and the thermally conductive sheet, and they are not in close contact with each other.

[0035] 9(b), when the semiconductor device 300 is heated in the mold of the transfer molding device 601, the volume expansion material 346 embedded in the thermally conductive sheet 440 expands, and the thermally conductive sheet 440 expands in the thickness direction, thereby coming into close contact with a part of the inclined portion 461. On the other hand, since the flat portion 460 of the thermally conductive sheet 440 is pressurized, the expansion of the thermally conductive sheet 440 is suppressed.

[0036] Then, when sealing material 360 is injected into the mold, semiconductor device 300 is pressurized with molding pressure 347. When molding pressure 347 reaches a predetermined pressure level, it suppresses expansion force 348 of thermally conductive sheet 440, preventing thermally conductive sheet 440 from expanding. Therefore, molding pressure 347 needs to be smaller than the force that flat portion 460 applies to thermally conductive sheet 440. In other words, it is desirable that pressure force 349 applied by the conductor plate to thermally conductive sheet 440 be larger than molding pressure 347 applied by sealing material 360 to the conductor plate and thermally conductive sheet 440, respectively.

[0037] 9(c), unexpanded portion 346a of volumetric expansion material 346 embedded in resin insulating layer 442 hardly expands due to pressure force 349 in flat portion 460 of the conductive plate. On the other hand, in inclined portion 461 of the conductive plate and outside thereof, portion 346b of the volumetric expansion material facing inclined portion 461 expands, increasing the thickness of heat conduction sheet 440. Note that it is sufficient that at least a portion of inclined portion 461 is covered by expanded volumetric expansion material 346.

[0038] (Thermal conductive sheet manufacturing process) (Figure 10) The manufacturing process of the thermally conductive sheet 440 will be described using Figures 10(a) to 10(c). Figure 10(a) shows the state in which an unreacted resin insulating layer 442a before compression has been applied to the surface of a metal foil 444 and then dried. The resin insulating layer 442a is a foam material having voids (air bubbles) 350 and containing a thermally conductive filler. Note that by heating the resin insulating layer 442a when it is applied, the elastic modulus of the resin insulating layer 442a is made lower than that at room temperature.

[0039] 10(b), the thermally conductive sheet 440 is heated and pressurized by a pressure device 450. The heating temperature of the thermally conductive sheet 440 is desirably a temperature at which the Young's modulus is 1 / 100 or less of the Young's modulus of the thermally conductive sheet 440 after coating and drying in FIG. 10(a). This is because if the Young's modulus is more than 1 / 100, the voids are difficult to compress and the compressed state of the compressed voids is difficult to maintain.

[0040] Furthermore, during the pressurization process using pressurizing device 450, the temperature is preferably set at a temperature at which the thermosetting component, such as epoxy resin, incorporated in thermally conductive sheet 440 hardly reacts, and the pressurization temperature and pressurization time are preferably set so that the reaction rate of the thermosetting component is within 30% to prevent a decrease in adhesiveness. The reaction rate shown here is based on the peak area of ​​the curing reaction after coating and drying when the temperature is increased at a rate of 10°C / min using a differential scanning calorimeter, and is represented by the decrease in area. Furthermore, the pressure applied to thermally conductive sheet 400 by pressurizing device 450 is preferably greater than the pressure applied by spring 602 in the transfer molding process.

[0041] As shown in FIG. 10( c), by applying high pressure to the thermally conductive sheet 440 to cause volumetric contraction, the voids 350 are also compressed by high pressure and volumetric contraction, increasing the internal pressure of the compressed voids 350. By compressing the thermally conductive sheet 440 to a semi-cured state in this manner, the volumetric expansion force of the thermally conductive sheet 440 can be increased. The compressed thermally conductive sheet 440 is heated and pressurized for a predetermined time, and then cooled to room temperature while maintaining the pressurized state. This improves the Young's modulus of the thermally conductive sheet 440 while keeping the voids 350 compressed, allowing the compressed state of the voids 350 to be maintained. The compressed voids 350 function as volumetric expansion bodies in the thermally conductive sheet 440. When the thermally conductive sheet 440 is heated during transfer molding, the elastic modulus of the resin insulating layer 442 decreases, and the internal pressure of the voids 350 exceeds the reaction force due to the elastic modulus of the resin insulating layer 442, causing the voids 350 to expand in volume.

[0042] (Figure 11) The present invention and a comparative example will be examined. Fig. 11 shows the thermal resistance and the ratio of the gap to the thickness of the thermally conductive sheet 440. The graph indicated by black circles shows the case where the sealant 360 is filled in the gap between the conductive plate and the thermally conductive sheet 440, while the graph indicated by white circles shows the case of the present invention where the thermally conductive sheet 440 expands in volume and adheres closely to the conductive plate 360. The analysis was also performed assuming that the area affected by the gap was 10%, with 90% being the flat portion 460 of the conductive plate and 10% being a step simulating the inclined portion 461.

[0043] It can be seen that the thermal resistance increases as the ratio of gaps to the thickness of thermally conductive sheet 440 increases, since the thermal conductivity decreases as thermally conductive sheet 440 expands. It can be seen that the configuration of the present invention has lower thermal resistance and better heat dissipation than the comparative example.

[0044] (Figure 12) The power conversion device 200 includes inverter circuit units 140-142 and a capacitor module 500. The inverter circuit units 141 and 142 have the same basic circuit configuration, and also have the same control method and operation. The inverter circuit unit 140 is an inverter circuit for auxiliary equipment. The inverter circuit units 141 and 142 include multiple semiconductor devices 300, which are connected to each other to form a three-phase bridge circuit of U, V, and W phases. When the current capacity is large, the semiconductor devices 300 can be connected in parallel, and these parallel connections can be assigned to each phase of the three-phase inverter circuit to accommodate an increase in current capacity. In addition, the current capacity can also be increased by connecting active elements 155 and 157 and diodes 156 and 158 in parallel.

[0045] As described above, the upper arm circuit includes upper arm active element 155 and upper arm diode 156 as switching power semiconductor elements, and the lower arm circuit includes lower arm active element 157 and lower arm diode 158 as switching power semiconductor elements. Active elements 155 and 157 receive a drive signal output from one or the other of two driver circuits that make up driver circuit 174, perform a switching operation, and convert DC power supplied from battery 136 into three-phase AC power.

[0046] As described above, the upper arm active element 155 and the lower arm active element 157 each have a collector electrode, an emitter electrode, and a gate electrode. The upper arm diode 156 and the lower arm diode 158 each have two electrodes: a cathode electrode and an anode electrode. In the diodes 156 and 158, the cathode electrodes are electrically connected to the collector electrodes of the IGBTs 155 and 157, and the anode electrodes are electrically connected to the emitter electrodes of the active elements 155 and 157, respectively. As a result, the current flows in the forward direction from the emitter electrodes to the collector electrodes of the upper arm active element 155 and the lower arm active element 157.

[0047] It should be noted that a MOSFET (metal oxide semiconductor field effect transistor) may be used as the active element, in which case the upper arm diode 156 and the lower arm diode 158 are not required.

[0048] The positive terminal 315B and the negative terminal 319B of each upper and lower arm series circuit are respectively connected to DC terminals for connecting capacitors of the capacitor module 500. AC power is generated at the connection point between the upper arm circuit and the lower arm circuit, and the connection point between the upper arm circuit and the lower arm circuit of each upper and lower arm series circuit is connected to an AC side terminal 320B of each semiconductor device 300. The AC side terminal 320B of each phase is respectively connected to an AC output terminal of the power conversion device 200, and the generated AC power is supplied to the stator winding of the motor generator 192.

[0049] Control circuit 172 generates timing signals for controlling the switching timing of upper arm active element 155 and lower arm active element 157 based on input information from a vehicle-side control device, sensor (e.g., current sensor 180), etc. Driver circuit 174 generates drive signals for performing switching operations on upper arm active element 155 and lower arm active element 157 based on the timing signals output from control circuit 172. Connectors 181 are provided between each circuit component.

[0050] The upper and lower arm series circuits each include a temperature sensor (not shown), and temperature information about the upper and lower arm series circuits is input to the microcomputer. Voltage information about the DC positive side of the upper and lower arm series circuits is also input to the microcomputer. The microcomputer detects overtemperatures and overvoltages based on this information, and if an overtemperature or overvoltage is detected, the microcomputer stops the switching operations of all upper-arm active elements 155 and lower-arm active elements 157, thereby protecting the upper and lower arm series circuits from overtemperature or overvoltage.

[0051] (Fig. 13, Fig. 14) The power conversion device 200 is composed of circuit components, including an electric circuit body 400, housed in an upper case 10 and a lower case 11 that is open at the top. The upper case 10 closes the opening of the lower case 11, forming a housing formed in a rectangular parallelepiped shape. This makes it easier to install the power conversion device 200 in a vehicle or the like, and also improves productivity. The upper case 10 and the lower case 11 are made of an aluminum alloy or the like, and are fixed together while sealing the inside of the device. The housing formed by the upper case 10 and the lower case 11 may be integrated.

[0052] The housing of the power conversion device 200 contains an electric circuit body 400, a capacitor module 500, etc. A cooling water inlet pipe 13 and a cooling water outlet pipe 14, which communicate with the cooling flow path of the electric circuit body 400, protrude from the side of the housing to the outside.

[0053] A connector 18a is attached to one longitudinal side surface of the housing of the power conversion device 200, and an AC terminal is connected to this connector 18a. In addition, a connector 21 is provided on the surface from which the cooling water inlet pipe 13 and the cooling water outlet pipe 14 are led out.

[0054] A control circuit 172 and a driver circuit 174 are arranged above the electric circuit body 400 inside the housing of the power conversion device 200. A capacitor module 500 is housed on the DC terminal side of the electric circuit body 400. The capacitor module 500 is arranged at the same height as the electric circuit body 400 inside the housing, which allows the power conversion device 200 to be made thinner, thereby improving the flexibility of installation in a vehicle.

[0055] An AC side terminal 320B of the electric circuit body 400 is joined to the bus bar through the current sensor 180. In addition, a positive side terminal 315B and a negative side terminal 319B, which are DC terminals of the semiconductor device 300, are joined to the positive terminal and the negative terminal of the capacitor module 500, respectively.

[0056] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0057] (1) The semiconductor device 300 includes a conductive plate having a semiconductor element bonded to one side thereof, a heat-conducting sheet 440 made of thermosetting resin adhered to the other side of the conductive plate, and a sealing material 360 that mold-seals the conductive plate and the heat-conducting sheet 440, the conductive plate having an inclined portion 461 at the outer peripheral end of the other side thereof, the heat-conducting sheet 440 adhering to at least a portion of the inclined portion, and the thickness of the heat-conducting sheet 440 is thicker at the sheet end facing the inclined portion than at the sheet center facing the portion of the other side of the conductive plate that is more inward than the inclined portion. This makes it possible to provide a semiconductor device 300 that combines heat dissipation properties with reliability.

[0058] (2) The thermally conductive sheet has a volume expansion portion that expands when heated, allowing the expanded thermally conductive sheet 440 to be bonded to the inclined portion 461 of the conductive plate.

[0059] (3) The volume expansion portion is made of a foam material. This allows for a semi-hardened thermal conductive sheet 440 with voids 350 compressed, which contributes to adhesion to the inclined portion 461 of the conductive plate.

[0060] (4) The volume expansion portion has voids 350 that are shrunk in volume by pressure. This contributes to the volume expansion when the thermally conductive sheet 440 is heated, and contributes to the adhesion to the inclined portion 461 of the conductive plate.

[0061] (5) The pressure 349 that the conductor plate applies to the thermally conductive sheet 440 is greater than the molding pressure 347 that the sealing material 360 applies to the conductor plate and the thermally conductive sheet 440. This contributes to the adhesion of the thermally conductive sheet 440 to the inclined portion 461 of the conductor plate without suppressing the expansion of the thermally conductive sheet 440.

[0062] (6) In the heat conduction sheet 440, the surface opposite to the surface that is in close contact with the conductive plate is in contact with the cooling member 340. In this way, the semiconductor device 300 can be cooled.

[0063] (7) The power conversion device 200 includes the above-described semiconductor device 300. In this way, it is possible to provide the power conversion device 200 that achieves both heat dissipation and reliability.

[0064] (8) A method for manufacturing a semiconductor device 300 including a conductor plate having a semiconductor element bonded to one side thereof, a thermally conductive sheet 440 made of thermosetting resin adhered to the other side of the conductor plate, and a sealant for mold-sealing the conductor plate and the thermally conductive sheet 440, the conductor plate having an inclined portion at the outer peripheral edge of the other side, the method comprising compressing the thermally conductive sheet 440 containing a thermally conductive filler to a semi-hardened state, placing the semi-hardened thermally conductive sheet 440 on the other side of the conductor plate, and heating the conductor plate and the thermally conductive sheet 440 while applying pressure in the thickness direction with a predetermined pressure. This manufacturing method allows for the manufacture of a semiconductor device 300 that combines high heat dissipation performance and reliability.

[0065] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted. [Explanation of symbols]

[0066] 10 Upper Case 11 Lower case 13 Cooling water inlet pipe 14 Cooling water outflow pipe 18 Exchange Terminal 155 Upper arm circuit active element (first power semiconductor element) 156 Upper arm circuit diode (first power semiconductor element) 157 Lower arm circuit active element (second power semiconductor element) 158 Lower arm circuit diode (second power semiconductor element) 172 control circuit 174 Driver Circuit 180 Current Sensor 181 Connector 192 Motor Generator 200 Power conversion device 300 Semiconductor device 315B Positive side terminal 319B Negative terminal 320B AC side terminal 325 signal terminal 325C Voltage detection terminal 325K Kelvin emitter signal terminal 325L Lower arm gate signal terminal 325M Mirror emitter signal terminal 325U Upper arm gate signal terminal 340 Cooling Material 346 Volumetric expansion material 346a Unexpanded volumetric expansive material 346b Expanded volumetric expansive material 347 Molding pressure of sealing material 348 Expansion force of volumetric expansion materials 349 Pressure on flat part 350 Void 360 Encapsulating material 400 Electrical circuit body 420 Conductor Plate 430 First conductor plate (upper arm circuit emitter side) 431 Second conductor plate (upper arm circuit collector side) 432 Third conductor plate (lower arm circuit emitter side) 433 4th conductor plate (lower arm circuit collector side) 440 Insulation sheet (thermal conductive sheet) 442 Resin insulation layer 442a Resin insulation layer before compression 444 Metal foil 450 Pressure Device 453 Heat Conduction Materials 454 Resin parts 460 Flat area 461 Slope 500 Capacitor Module 601 Transfer molding equipment 602 Spring

Claims

1. a conductor plate having a semiconductor element bonded to one surface thereof; a thermally conductive sheet made of a thermosetting resin adhered to the other surface of the conductive plate; a sealing material that mold-seals the conductive plate and the thermally conductive sheet, the conductive plate has an inclined portion at an outer peripheral end of the other surface, the thermally conductive sheet is in close contact with at least a portion of the inclined portion; The thickness of the heat conductive sheet is such that the sheet end portion facing the inclined portion is thicker than the sheet center portion facing the portion on the other surface of the conductive plate that is more inward than the inclined portion. Semiconductor device.

2. 2. The semiconductor device according to claim 1, The thermally conductive sheet has a volume expansion portion that expands when heated. Semiconductor device.

3. 3. The semiconductor device according to claim 2, The volume expansion portion is made of a foam material. Semiconductor device.

4. 3. The semiconductor device according to claim 2, The volume expansion portion has a void that is shrunk in volume by pressure. Semiconductor device.

5. 2. The semiconductor device according to claim 1, The pressure applied by the conductive plate to the thermally conductive sheet is greater than the molding pressure applied by the sealing material to the conductive plate and the thermally conductive sheet. Semiconductor device.

6. 2. The semiconductor device according to claim 1, The surface of the heat conductive sheet opposite to the surface that is in close contact with the conductive plate is in contact with the cooling member. Semiconductor device.

7. A device comprising the semiconductor device according to any one of claims 1 to 6. Power conversion device.

8. A method for manufacturing a semiconductor device comprising: a conductor plate having a semiconductor element bonded to one surface thereof; a heat-conductive sheet made of a thermosetting resin in close contact with the other surface of the conductor plate; and a sealing material for molding and sealing the conductor plate and the heat-conductive sheet, wherein the conductor plate has an inclined portion at an outer peripheral end of the other surface thereof, The thermally conductive sheet containing the thermally conductive filler is compressed under pressure to be in a semi-hardened state, The semi-cured thermal conductive sheet is placed on the other surface of the conductive plate; The conductive plate and the thermally conductive sheet are heated while being pressed in the thickness direction with a predetermined pressure. A method for manufacturing a semiconductor device.

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