Circuit body, power conversion device, and method for manufacturing circuit body

Abstract

A circuit body is provided with: a semiconductor module in which a semiconductor element is sealed with a sealing material, and which has, on at least one surface, a heat dissipation surface that dissipates heat generated by the semiconductor element; a cooling member that is disposed facing the heat dissipation surface of the semiconductor module and that cools heat generated by the semiconductor element; and a fixing member which is embedded in the sealing material of the semiconductor module and restricts movement of the cooling member in a direction away from the semiconductor module, the fixing member being configured from an embedded portion embedded in the sealing material and a fixing portion inserted into the cooling member and fixing the cooling member. At the boundary between the buried portion and the fixed portion, the buried portion has a blank portion that surrounds the outer periphery of the fixed portion and is exposed from the surface of the sealing material.

Description

Technical Field

[0001] The present invention relates to a circuit body, a power conversion device, and a method for manufacturing the circuit body. Background Art

[0002] Power conversion devices, which convert DC power into AC power through the switching action of semiconductor elements, are widely used in residential, automotive, railway, and substation applications due to their high conversion efficiency. These semiconductor elements generate heat during switching. Therefore, in semiconductor modules incorporating these elements, a cooling member is positioned opposite the semiconductor module and secured to the module via a fixing member to cool the heat generated by the semiconductor elements.

[0003] The semiconductor device disclosed in Patent Document 1 comprises: a packaging substrate on which a semiconductor chip is mounted; a sealing resin layer formed on the packaging substrate to seal the periphery of the semiconductor chip; and a fixing member, one end of which is embedded in the sealing resin layer and is used to fix other components on the side of the packaging substrate on which the semiconductor chip is mounted by clamping the semiconductor chip. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-109794 Summary of the Invention Problems to be solved by the invention

[0005] As in the device described in Patent Document 1, the fixing member embedded in the sealing material of the semiconductor module needs to be provided so as to protrude from the semiconductor module. However, in this case, there is a problem in that the sealing material overflows near the fixing member. Technical means to solve the problem

[0006] The circuit body of the present invention comprises: a semiconductor module, which seals a semiconductor element with a sealing material and has a heat dissipation surface on at least one surface, and the heat dissipation surface dissipates heat generated by the semiconductor element; a cooling member, which is arranged opposite to the heat dissipation surface of the semiconductor module and cools the heat generated by the semiconductor element; and a fixing member, which is embedded in the sealing material of the semiconductor module and limits the movement of the cooling member in a direction away from the semiconductor module, the fixing member being composed of a buried portion buried in the sealing material and a fixing portion inserted into the cooling member and fixing the cooling member, and at the boundary between the buried portion and the fixing portion, the buried portion has a blank portion surrounding the outer periphery of the fixing portion and exposed from the surface of the sealing material. In the manufacturing method of the circuit body of the present invention, the circuit body includes a semiconductor element, a cooling member for cooling the heat generated by the semiconductor element, and a fixing member for fixing the cooling member, and the semiconductor element and the fixing member are sealed with a sealing material, and the fixing member is composed of a buried portion buried in the sealing material and a fixing portion inserted into the cooling member and fixing the cooling member, and at the boundary between the buried portion and the fixing portion, the buried portion has a blank portion surrounding the outer periphery of the fixing portion and exposed from the surface of the sealing material. The manufacturing method includes: arranging the circuit body including the semiconductor element and the fixing member in a mold, after the mold is tightly attached to the blank portion of the fixing member, injecting the sealing material into the mold to manufacture a semiconductor module; and a process of fixing the cooling member to the semiconductor module by the fixing member after the sealing material is solidified. Effects of the Invention

[0007] According to the present invention, it is possible to prevent the sealing material from flowing out in the vicinity of the fixing member. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a top view of the circuit body. Figure 2 (a) and (b) are cross-sectional views of the circuit body. Figure 3 It is a perspective view of a cross section of the circuit body taken along line YY. Figure 4 It is a cross-sectional perspective view of the circuit body taken along line XX. Figure 5 This is a semi-perspective top view of a semiconductor module. Figure 6 This is a circuit diagram of a semiconductor module. Figure 7 (a) to (c) are diagrams showing the steps of manufacturing a semiconductor module. Figure 8 (a) to (c) are diagrams showing the steps of fixing the cooling member to the semiconductor module. Figure 9 It is a cross-sectional view explaining the method for manufacturing the circuit body according to Modification 1. Figure 10 It is a top view of the circuit body in the comparative example. Figure 11 This is a cross-sectional view of a circuit body according to Modification 2. Figure 12 (a) and (b) are diagrams showing the steps of manufacturing the semiconductor module according to the second modification. Figure 13 (a) to (c) are views showing the steps of fixing the cooling member to the semiconductor module according to the second modification. Figure 14 This is a cross-sectional view of a circuit body according to Modification 3. Figure 15 This is a cross-sectional view of a circuit body according to Modification 4. Figure 16 This is a cross-sectional view of a circuit body according to Modification 5. Figure 17 This is a semi-transparent plan view of a semiconductor module according to Modification 6. Figure 18 This is a circuit diagram of a power conversion device using a semiconductor module. Figure 19 This is a perspective view of the power conversion device. Figure 20 It is a perspective view of a cross section of the power conversion device taken along line XV-XV. DETAILED DESCRIPTION

[0009] The following describes embodiments of the present invention with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention and have been omitted or simplified as appropriate for clarity of description. The present invention may also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

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

[0011] When there are multiple identical or identical components or components having the same function, different subscripts may be added to the same reference numerals for description. However, when there is no need to distinguish these multiple components, the subscripts may be omitted for description.

[0012] Figure 1 4 is a top view of the circuit body 400 in the embodiment of the present invention. The circuit body 400 is composed of the semiconductor module 300, the cooling member 340, the fixing member 341, etc. Figure 1 In the example shown, the circuit body 400 includes three semiconductor modules 300 arranged in parallel.

[0013] The semiconductor module 300 is sealed with a sealing material 360 and contains semiconductor elements 155 and 157. The heat generated by the switching operation of the semiconductor elements 155 and 157 is dissipated from both sides of the semiconductor module 300. Furthermore, the terminals connecting the semiconductor module 300 and the semiconductor elements 155 and 157 are led out from the sealing material 360 on the side of the semiconductor module 300. These terminals are connected to the capacitor module 500 (see FIG. 5 ) of the DC circuit. Figure 18) connected to the positive terminal 325P and the negative terminal 325M, and the AC circuit motor generator 192, 194 (refer to Figure 18 ) is connected to the AC side terminal 325A, etc., a power terminal through which large current flows.

[0014] In addition, the terminals extending from the sealing material 360 on the side of the semiconductor module 300 are the lower arm gate terminal 325L, the collector detection terminal 325C, the emitter detection terminal 325E, and the upper arm gate terminal 325U. These terminals extending from the semiconductor module 300 are connected to wiring patterns such as the wiring pattern of the substrate (not shown). The circuit body 400 in which three semiconductor modules 300 are arranged in parallel serves as a power conversion device 200 (see FIG. 1 ) that converts DC power and AC power into each other through the switching action of the semiconductor elements 155 and 157. Figure 18 ) to function. In addition, the number of semiconductor modules 300 included in the circuit body 400 is not limited to three and can be arbitrarily set according to various aspects of the circuit body 400.

[0015] Cooling member 340 is positioned opposite semiconductor module 300 and cools the heat generated by the switching operation of semiconductor elements 155 and 157. Specifically, cooling member 340 has a flow path for refrigerant flow formed within it. The refrigerant flowing through the flow path cools the heat generated by semiconductor elements 155 and 157. Water or antifreeze solution containing ethylene glycol mixed with water is used as the refrigerant. Cooling member 340 is preferably made of aluminum, which has high thermal conductivity and is lightweight. It is manufactured through extrusion, forging, brazing, and other methods.

[0016] The fixing member 341 is embedded in the sealing material 360 provided in the semiconductor module 300, and restricts the movement of the cooling member 340 away from the semiconductor module 300. Figure 1 In the illustrated example, fixing members 341 are provided at four corners of each semiconductor module 300. The configuration of the fixing members 341 will be described later.

[0017] Figure 2 (a) Figure 2 (b) is a cross-sectional view of the circuit body 400 . Figure 2 (a) is Figure 1 The circuit body 400 is shown in a cross-sectional view along line XX. Figure 2 (b) is Figure 1 The circuit body 400 is shown in a cross-sectional view of a portion of the semiconductor module 300 taken along line YY. Figure 3 yes Figure 1 The circuit body 400 is shown in a perspective cross-sectional view along line YY. Figure 4 yes Figure 1The illustrated cross-sectional perspective view of the circuit body 400 taken along line XX shows the semiconductor module 300 without the cooling member 340 .

[0018] like Figure 2 As shown in (a), as the first semiconductor element forming the upper arm circuit of the power conversion device 200, an active element 155 and a diode 156 (see the following) are provided. Figure 5 、 Figure 6 As an active element, Si, SiC, GaN, GaO, C, etc. can be used. When the body diode of the active element 155 is used, the additional diode can be omitted. Figure 2 (b) Figure 3 As shown, a second conductor plate 431 is bonded to the collector side of the first semiconductor element 155. Solder or sintered metal may be used for this bonding. A first conductor plate 430 is bonded to the emitter side of the first semiconductor element 155.

[0019] like Figure 2 (b) Figure 3 As shown, as the second semiconductor element forming the lower arm circuit, an active element 157 and a diode 158 (see later described) are provided. Figure 5 、 Figure 6 The fourth conductor plate 433 is bonded to the collector side of the second semiconductor element 157. The third conductor plate 432 is bonded to the emitter side of the second semiconductor element 157.

[0020] Conductor plates 430, 431, 432, and 433 are not particularly limited as long as they are made of a material with high electrical and thermal conductivity. However, preferably, metal materials such as copper or aluminum materials, or composite materials of metal materials and high thermal conductivity materials such as diamond, carbon, or ceramics are used. These materials can be used alone, but may also be plated with Ni, Ag, or the like to improve bonding with solder or sintered metal.

[0021] like Figure 2 (a) Figure 2 (b) Figure 3 、 Figure 4 As shown, the conductor plates 430, 431, 432, and 433 not only conduct electricity but also function as heat transfer members, transferring heat generated by the semiconductor elements 155, 156, 157, and 158 to the cooling member 340. The surfaces opposite the surfaces bonded to the semiconductor elements 155, 156, 157, and 158 serve as the heat dissipation surfaces of the conductor plates 430, 431, 432, and 433. Because the potentials of the conductor plates 430, 431, 432, and 433 differ from those of the cooling member 340, an insulating sheet 440 is placed between the heat dissipation surfaces.

[0022] The insulating sheet 440 is constructed by laminating a resin insulating layer 443 and a surface conductor layer 444. The resin insulating layer 443 covers the conductor plates 430, 431, 432, 433 on one side and is bonded to the heat dissipation surface of the conductor plates 430, 431, 432, 433. The resin insulating layer 443 is not particularly limited as long as it is a resin insulating layer that has adhesion to the conductor plates 430, 431, 432, 433, but an epoxy resin-based resin insulating layer in which a powdered inorganic filler is dispersed is preferred. This is because the balance between adhesion and heat dissipation properties is good. 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 module 300, contacting the heat-conducting member 453 described later. The surface conductor layer 444 is, for example, a metal foil.

[0023] Insulating sheet 440 is cured simultaneously with sealing material 360 during the transfer molding process. During the transfer molding process, when insulating sheet 440 is placed in the mold, a release sheet or surface conductive layer 444 is provided on the contact surface between insulating sheet 440 and the mold to prevent adhesion. Due to its poor thermal conductivity, the release sheet must be removed after transfer molding. However, when using a surface conductive layer 444 such as metal foil, selecting a copper or aluminum-based metal with high thermal conductivity allows it to be used without removal after transfer molding.

[0024] Semiconductor elements 155, 156, 157, 158, and conductor plates 430, 431, 432, and 433 are sealed with a sealing material 360 by transfer molding, thereby forming a semiconductor module 300. Cooling members 340 are disposed on both sides of the semiconductor module 300 and fixed to the semiconductor module 300 by fixing members 341. In this embodiment and the modified examples described below, the circuit body 400 is described as having cooling members 340 disposed on both sides of the semiconductor module 300. However, the circuit body 400 may also be configured such that the cooling member 340 is disposed on only one side of the semiconductor module 300. In this case, a frame or mounting member is disposed on the other side of the semiconductor module 300, and the other side of the semiconductor module 300 is fixed to the frame or mounting member by fixing members 341.

[0025] The heat conducting member 453 is provided between the semiconductor module 300 and the cooling member 340 to reduce the contact thermal resistance. The heat conducting member 453 can be made of a heat conducting material that is fluid at room temperature or high temperature, such as grease, gel grease, or a phase change plate. However, to ensure operability and long-term reliability, a curing type heat conducting material that is fluid when uncured and has no fluidity after curing is preferred. The curing type heat conducting member 453 has the advantages of low viscosity during application, excellent operability, and improved mechanical properties through curing. Curing can be achieved by thermal curing, moisture curing, ultraviolet curing, etc., but thermal curing is preferred for deep curing.

[0026] The fixing member 341 is embedded in the sealing material 360 provided in the semiconductor module 300. Figure 2 As shown in (b), it is composed of a buried portion 344 buried in the sealing material 360, a blank portion 343 exposed on the surface of the sealing material 360, and a fixed portion 342 protruding from the sealing material 360. That is, the fixing member 341 passes through the semiconductor module 300 along the thickness direction of the semiconductor module 300, and a blank portion 343 is formed at both ends thereof. The details of the blank portion 343 will be described later. The fixing portion 342 of the fixing member 341 protruding from the sealing material 360 is inserted into the cooling member 340, and the cooling member 340 is fixed to the semiconductor module 300 by mechanical connection such as snap-fitting and screw fixing. Figure 2 (b) Figure 4 In the example shown, a cutout is provided on the fixing portion 342 of the fixing member 341, and a protrusion that engages with the cutout is provided on the cooling member 340. By moving the cooling member 340 parallel to the surface of the semiconductor module 300, the cutout of the fixing portion 342 of the fixing member 341 engages with the protrusion of the cooling member 340.

[0027] like Figure 2 (b) Figure 4 As shown, fixing members 341 are provided at the four corners of semiconductor module 300 and have margins 343 exposed flush with the surface 361 of the sealing material 360 of semiconductor module 300, and fixing portions 342 protruding from the surface 361 of the sealing material 360 of semiconductor module 300. Specifically, fixing member 341 is composed of a buried portion 344 embedded in the sealing material 360 and a fixing portion 342 inserted into and securing the cooling member 340. At the boundary between buried portion 344 and fixing portion 342, buried portion 344 has margins 343 surrounding the outer periphery of fixing portion 342 and protruding from the surface 361 of the sealing material 360. Furthermore, margins 343 and the surface 361 of the sealing material 360 of semiconductor module 300 are coplanar.

[0028] Figure 5 FIG. 3 is a semi-perspective top view of the semiconductor module 300 . Figure 6 is a circuit diagram of the semiconductor module 300 .

[0029] like Figure 5 、 Figure 6As shown, positive-side terminal 325P is output from the collector side of the upper arm circuit and connected to the positive side of a battery or capacitor. Upper-arm gate terminal 325U is output from the gate of active element 155 of the upper arm circuit. Negative-side terminal 325M is output from the emitter side of the lower arm circuit and connected to the negative side of a battery or capacitor or GND. Lower-arm gate terminal 325L is output from the gate of active element 157 of the lower arm circuit. AC-side terminal 325A is output from the collector side of the lower arm circuit and connected to the motor. In the case of grounded neutral point, the lower arm circuit is connected to the negative side of the capacitor instead of GND.

[0030] The emitter detection terminal 325E of the upper arm outputs a signal from the emitter of the active element 155 in the upper arm circuit, while the emitter detection terminal 325E of the lower arm outputs a signal from the emitter of the active element 157 in the lower arm circuit. The collector detection terminal 325C of the upper arm outputs a signal from the collector of the active element 155 in the upper arm circuit, while the collector detection terminal 325C of the lower arm outputs a signal from the collector of the active element 157 in the lower arm circuit.

[0031] Furthermore, 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 diode 156 of the 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 diode 158 of the semiconductor element (lower arm circuit).

[0032] The semiconductor module 300 of this embodiment has a 2-in-1 structure, integrating two arm circuits, an upper arm circuit and a lower arm circuit, into a single module. Alternatively, a structure can be used in which multiple upper arm circuits and lower arm circuits are integrated into a single module. In this case, the number of output terminals from the semiconductor module 300 can be reduced, achieving miniaturization.

[0033] Figure 7 (a)~(c) Figure 8 (a) to (c) are cross-sectional views illustrating steps in the method for manufacturing the circuit body 400. Figure 2 Similar to (b), a cross-sectional view of a portion of the semiconductor module 300 is shown along line YY.

[0034] Figure 7 (a) to (c) represent the process of placing the circuit body 310 including semiconductor elements 155 and 156 and the fixing member 341 in the mold 603, tightly attaching the mold 603 to the blank portion 343 of the fixing member 341, and then injecting the sealing material 360 into the mold 603 to manufacture the semiconductor module 300. Figure 8(a) to (c) show the steps of fixing the cooling member 340 to the semiconductor module 300 by the fixing member 341 after the sealing material 360 is cured.

[0035] Figure 7 (a) is a temporary fixing process. The collector side of the semiconductor element 155 and the cathode side of the semiconductor element 156 are connected to the second conductor plate 431, and the gate electrode, emitter detection electrode, and collector electrode of the semiconductor element 155 are connected to the upper arm gate terminal 325U, emitter detection terminal 325E, and collector detection terminal 325C, respectively, by wire bonding. Furthermore, the emitter side of the semiconductor element 155 and the anode side of the semiconductor element 156 are connected to the first conductor plate 430 to form the circuit body 310 on the upper arm side. Similarly, the collector side of the semiconductor element 157 and the cathode side of the semiconductor element 158 ​​are connected to the fourth conductor plate 433, and the gate electrode, emitter detection electrode, and collector electrode of the semiconductor element 157 are connected to the gate terminal 325L, emitter detection terminal 325E, and collector detection terminal 325C, respectively, of the lower arm by wire bonding.

[0036] Furthermore, the emitter side of semiconductor element 157 and the anode side of semiconductor element 158 ​​are connected to third conductor plate 432 to form circuit body 310 on the lower arm side. Next, insulating sheet 440 is temporarily fixed to conductor plates 430-433. Temporary fixing means temporarily attaching insulating sheet 440 using its adhesive strength, leaving room for curing and bonding during the subsequent transfer molding process.

[0037] Figure 7 (b)~ Figure 7 (c) is a transfer molding process. The transfer molding device 601 is equipped with a spring 602 in the mold 603. By using the spring 602, even if the height of the circuit body 310 deviates, excessive pressure will not be applied to the semiconductor elements 155 to 158, and the force of the spring 602 can be used to apply a prescribed load. In addition, the transfer molding device 601 has a vacuum degassing mechanism not shown in the figure. By performing vacuum degassing, even if the sealing material 360 composed of resin or the like is involved in the gap, the gap can be compressed to a smaller size, thereby improving the insulation. In addition, by covering the circuit body 310 with a release film not shown in the figure, it is possible to prevent resin burrs from invading the spring drive part, etc.

[0038] like Figure 7As shown in (b), the circuit body 310, with the insulating sheet 440 temporarily attached, and the fixing member 341 are placed in a mold 603 preheated to a constant temperature of 175°C. The mold 603 is formed with a recess 604 into which the fixing portion 342 of the fixing member 341 enters. At the boundary between the buried portion 344 of the fixing member 341 and the fixing portion 342, the recess 604 is larger than the outer perimeter of the fixing portion 342 and smaller than the outer perimeter of the blank portion 343.

[0039] Then, if Figure 7 As shown in (c), the upper and lower molds 603 are clamped. At this time, the insulating sheet 440 and the conductor plates 430 to 433 are pressurized and adhered to each other by the spring 602. At the same time, a pressure 348 is applied to the blank portion 343 of the fixing member 341 from the upper and lower molds 603, and the opening of the recessed portion 604 of the mold 603 is in close contact with the blank portion 343. In this state, the sealing material 360 is injected into the mold 603. Therefore, the sealing material 360 can be prevented from flowing out toward the fixing portion 342 near the fixing portion 342 of the fixing member 341, and the buried portion 344 of the fixing member 341 can be firmly sealed and fixed in the sealing material 360. In addition, since the sealing material 360 can be prevented from flowing out toward the fixing portion 342, there is no need for an additional process such as removing the sealing material 360 attached to the fixing portion 342 to expose the fixing portion 342.

[0040] Then, if Figure 8 As shown in (a), the semiconductor module 300 sealed with the sealing material 360 is taken out from the transfer molding device 601 and post-cured at 175° C. for more than 2 hours.

[0041] Then, if Figure 8 As shown in (b), after the sealing material 360 is cured, the cooling member 340 is mounted on the semiconductor module 300. Specifically, the heat conductive member 453 is applied to the cooling member 340, and after the cooling member 340 is clamped from both sides, the cooling member 340 is moved along the heat dissipation surface so that the protrusion provided on the cooling member 340 engages with the notch of the fixing portion 342 of the fixing member 341, and is then mounted on the fixing portion 342.

[0042] Then, if Figure 8 As shown in (c), the cooling member 340 is fixed to the semiconductor module 300. Thus, the cooling member 340 is firmly fixed to the semiconductor module 300 via the fixing member 341 via the heat conducting member 453, and integrally constitutes the circuit body 400. Although not shown, a member is attached to prevent the convex portion of the cooling member 340 from disengaging from the notch of the fixing portion 342 to prevent the cooling member 340 from moving along the heat dissipation surface.

[0043] Next, refer to Figure 2 (b) Figure 7 (b) and the like will now describe the fixing member 341. The fixing portion 342 of the fixing member 341 needs to mechanically fix the cooling member 340 and withstand stresses such as thermal stress and vibration. Therefore, the diameter Φ of the fixing portion 342 needs to be at least 2.5 mm. To provide a margin for reliability, the diameter Φ is preferably at least 4.5 mm. A larger fixing portion 342 would increase the size of the semiconductor module 300. Therefore, the diameter Φ of the fixing portion 342 is preferably 10 mm or less.

[0044] At the boundary between the buried portion 344 and the fixed portion 342 of the fixing member 341, in order to prevent the outflow of the sealing material 360, the relationship between the size of the outer periphery of the fixing portion 342 and the size of the outer periphery of the blank portion 343 is preferably the following interval. Here, the interval refers to the distance between the outer periphery of the fixing portion 342 and the outer periphery of the blank portion 343 at the closest point. If the interval is greater than 0.5 mm, the sealing material 360 can be prevented from flowing out to the fixing portion 342 during the transfer molding process, but resin burrs may sometimes be generated in the fixing portion 342. Therefore, the interval is preferably greater than 1 mm. On the other hand, if the blank portion 343 becomes larger, the size of the semiconductor module becomes larger, so the interval is preferably less than 10 mm.

[0045] Fixing member 341 can be made of metals such as copper and aluminum, fiber-reinforced plastics (FRP), or ceramics. When electrically connecting fixing member 341 to cooling member 340 and grounding the fixing member 341, it is preferably made of a conductive material. A cylindrical shape is preferred because it is not necessary to consider the orientation when inserting the fixing member 341 into the transfer molding die. However, a prismatic or other shape is also acceptable.

[0046] When the material of the blank portion 343 is lower in hardness than the material used in the mold 603, the blank portion 343 is easily deformed, thereby suppressing wear of the mold 603. Furthermore, when the material of the fixing portion 342 is higher in hardness than the blank portion 343, the mechanical strength of the fixing portion 342 is increased, thereby maintaining high reliability when fixing the cooling unit member 340 even when vibration, thermal stress, etc. are applied.

[0047] Figure 9 1 is a cross-sectional view illustrating a method for manufacturing the circuit body 400 according to Modification 1. Figure 7 The process of the semiconductor module 300 of (c) is the same as that of the semiconductor module 300, and a cross-sectional view of a portion of the semiconductor module 300 taken along line YY is shown. Figure 7 The same parts in (c) are marked with the same symbols and their descriptions are simplified.

[0048] In this modification 1, the fixing member 341 uses a member whose buried portion 344 is slightly longer than the space formed by the upper and lower molds 603. In addition, the material of the blank portion 343 is preferably lower in hardness than the material of the mold 603.

[0049] like Figure 9 As shown, the upper and lower molds 603 are clamped. At this time, the upper and lower molds 603 apply pressure 348 to the fixing member 341, causing the blank portion 343 to deform toward its outer periphery, forming a deformed portion 347. Thus, even if there are dimensional deviations in the length of the fixing member 341, the blank portion 343 and the mold 603 can be kept in close contact. In mass production processes, components with dimensional deviations are sometimes used, but by forming the deformed portion 347 on the outer periphery of the blank portion 343, the dimensional deviations can be absorbed and the sealing material 360 can be prevented from flowing toward the fixing portion 342.

[0050] Figure 10 4 is a top view of a circuit body 400' in a comparative example. This comparative example is a generally assumed example in which the semiconductor module 300 and the cooling member 340 are firmly fixed, without applying the present embodiment, for comparison with the present embodiment. Figure 1 The same parts are marked with the same symbols.

[0051] and Figure 1 Similarly, circuit body 400' has three semiconductor modules 300 arranged in parallel, and cooling members 340 are fixed to the semiconductor modules 300 by fixing members 341. Here, fixing members 341 are not embedded in sealing material 360 provided on each semiconductor module 300, but are provided between the semiconductor modules 300, sandwiching cooling members 340 on both sides.

[0052] Typically, the cooling member 340 is grounded via the fixing member 341, etc., and a potential is applied between the terminal derived from the semiconductor module 300 and the cooling member 340. In addition, the fixing portion 342 is preferably made of a metal material in terms of cost and mechanical strength, and has the same potential as the cooling member 340. Therefore, an insulation distance needs to be obtained between the terminal and the cooling member 340, and between the terminal and the fixing member 341. When the system voltage of the inverter composed of the semiconductor module 300 becomes a high voltage greater than the currently common 400V, for example, a high voltage greater than 800V, a greater insulation distance is required. In addition, the circuit body 400' needs to have increased strength against thermal stress and vibration, etc. Therefore, as Figure 10 As shown in the comparative example of FIG, between the semiconductor modules 300 and on the outside of each semiconductor module 300, fixing members 341 such as screws are used to firmly fix the cooling member 340 to each semiconductor module 300.

[0053] Furthermore, when the voltage reaches 800V or higher, the terminals connected to the semiconductor module 300 also require an insulation distance corresponding to the potential difference. Specifically, in inverters operating at 800V or higher, the distance between the terminals tends to be wider than in the currently common 400V class. In this case, the presence of a metallic fixing member 341 near the terminals limits the flexibility of terminal placement, and to ensure the insulation distance, the circuit body 400' becomes larger.

[0054] Compared to this comparative example, in this embodiment, the buried portion 344 of the fixing member 341 is embedded in the sealing material 360, and the fixing portion 342 of the fixing member 341 is exposed on the surface of the sealing material 360 to fix the cooling member 340. In this way, by burying the fixing member 341 in the sealing material 360, the insulation between the fixing member 341 and the terminal is enhanced, and as a result, the physical distance between the fixing member 341 and the terminal can be reduced. On this basis, the cooling member 340 can be firmly fixed using the fixing portion 342 of the fixing member 341 exposed on the surface of the sealing material 360. Therefore, even when the circuit body 400 is applied to a high-voltage inverter, the increase in the size of the inverter can be suppressed.

[0055] Figure 11 4 is a cross-sectional view of a circuit body 400 according to Modification 2. Figure 11 and Figure 2 (b) is the same as Figure 1 A cross-sectional view of a portion of the semiconductor module 300 taken along line YY of the circuit body 400 is shown. Figure 2 The same parts as in (b) are denoted by the same symbols and their descriptions are simplified.

[0056] like Figure 11 As shown, in Modification 2, a fixing member 341 extends through the semiconductor module 300 along its thickness direction and has blank portions 343 formed at both ends. The blank portions 343 are flush with the surface 361 of the sealing material 360 of the semiconductor module 300. Furthermore, a fixing portion 342 of the fixing member 341 extends through the cooling member 340 and is formed of a fastening member such as a screw. The fixing portion 342, formed of a fastening member such as a screw, engages with a receiving hole provided in the buried portion 344, clamping the cooling member 340, thereby fastening the cooling member 340 to the semiconductor module 300. Blank portions 343 are formed around the outer periphery of the receiving hole provided in the buried portion 344.

[0057] In this second modification, the sealing material 360 can also be prevented from flowing out toward the fixing portion 342 of the fixing member 341 near the fixing portion 342, and the buried portion 344 of the fixing member 341 can be securely sealed and fixed within the sealing material 360. Furthermore, by using the fixing member 341 formed of a fastening member such as a screw, even if there are dimensional variations in the cooling member 340, such as thickness, the cooling member 340 can be securely fixed to the semiconductor module 300 by fastening in accordance with the dimensional variations.

[0058] Figure 12 (a)~(b), Figure 13 (a) to (c) are cross-sectional views illustrating the steps in the method for manufacturing the circuit body 400 according to the second modification. Figure 2 Similar to (b), a cross-sectional view of a portion of the semiconductor module 300 is shown along line YY. Figure 12 (a) to (b) show the steps of manufacturing the semiconductor module 300. Figure 13 (a) to (c) show the steps of fixing the cooling member 340 to the semiconductor module 300 using the fixing member 341 .

[0059] like Figure 12 As shown in (a), in the temporary fixing step, the insulating sheet 440 is temporarily fixed to the conductor plates 430 to 433. Then, the fixing member 341 is prepared, and the insertion member 349 for positioning is installed in the receiving hole provided in the buried portion 344 of the fixing member 341.

[0060] like Figure 12 As shown in (b), during the transfer molding process, the circuit body 310, with the insulating sheet 440 temporarily fixed thereto, and the fixing member 341 are placed in a mold 603 preheated to a constant temperature of 175°C. Since an insert member 349 is attached to the fixing member 341, the insert member 349 enters the recess 604 formed in the mold 603, thereby holding the fixing member 341 in a predetermined position within the mold 603. A blank portion 343 is formed around the outer periphery of the receiving hole provided in the buried portion 344.

[0061] When the upper and lower molds 603 are clamped, pressure is applied from the upper and lower molds 603 to the margin portion 343 of the fixing member 341, and the periphery of the opening of the recessed portion 604 of the mold 603 comes into close contact with the margin portion 343. In this state, the sealing material 360 is injected into the mold 603. This prevents the sealing material 360 from flowing toward the fixing portion 342 of the fixing member 341 near the fixing portion 342, and furthermore, the buried portion 344 of the fixing member 341 can be securely sealed and fixed within the sealing material 360.

[0062] Then, if Figure 13 As shown in (a), the semiconductor module 300 sealed with the sealing material 360 is taken out from the transfer molding device 601, and the insert member 349 is removed. Figure 13 As shown in (b), post-curing is performed at 175° C. for 2 hours or more.

[0063] Then, if Figure 13 As shown in (c), after the sealing material 360 is cured, the cooling member 340 is mounted on the semiconductor module 300. Specifically, a heat conductive member 453 is applied to the cooling member 340, and a fixing portion 342 composed of a fastening member such as a screw is engaged with a receiving hole provided in the buried portion 344, thereby fastening the cooling member 340 to the semiconductor module 300.

[0064] Figure 14 4 is a cross-sectional view of a circuit body 400 according to Modification 3. Figure 14 and Figure 2 (b) is the same as Figure 1 A cross-sectional view of a portion of the semiconductor module 300 taken along line YY of the circuit body 400 is shown. Figure 2 The same parts as in (b) are denoted by the same symbols and their descriptions are simplified.

[0065] exist Figure 2 In (b), the fixing portion 342 of the fixing member 341 is provided with a cutout that engages with the convex portion provided on the cooling member 340 in a manner that does not penetrate the cooling member 340. In the modification 3, as Figure 14 As shown, the fixing portion 342 passes through the cooling member 340 and has a notch that engages with the cooling member 340. Since the entire thickness of the cooling member 340 is used for fixing, the cooling member 340 and the semiconductor module 300 are securely fixed. Furthermore, although not shown, a member is provided to prevent the cooling member 340 from moving along the heat dissipation surface to prevent the notch in the fixing portion 342 from disengaging from the cooling member 340.

[0066] Figure 15 4 is a cross-sectional view of a circuit body 400 according to Modification 4. Figure 15 and Figure 2 (b) is the same as Figure 1 A cross-sectional view of a portion of the semiconductor module 300 taken along line YY of the circuit body 400 is shown. Figure 2 The same parts as in (b) are denoted by the same symbols and their descriptions are simplified.

[0067] like Figure 15As shown, in Modification 4, the fixing portion 342 of the fixing member 341 penetrates the cooling member 340, and a nut is screwed into the threaded fixing portion 342 to secure the cooling member 340. Since the entire thickness of the cooling member 340 is used for fixation, the cooling member 340 and the semiconductor module 300 can be securely fixed. Furthermore, by using the fixing member 341 formed of a fastening member such as a screw, even if there are dimensional variations in the cooling member 340, the cooling member 340 can be securely fixed to the semiconductor module 300 by tightening according to these dimensional variations.

[0068] Figure 16 4 is a cross-sectional view of a circuit body 400 according to Modification 5. Figure 16 and Figure 2 (b) is the same as Figure 1 A cross-sectional view of a portion of the semiconductor module 300 taken along line YY of the circuit body 400 is shown. Figure 2 The same parts as in (b) are denoted by the same symbols and their descriptions are simplified.

[0069] In the fifth modification, the outer peripheral surface of the buried portion 344 of the fixing member 341 is subjected to a surface treatment for improving adhesion with the sealing material 360. Figure 16 In the example shown, the outer peripheral surface of the buried portion 344 is formed into a concavo-convex shape 345. Figure 16 In another example shown, the outer peripheral surface of the buried portion 344 is provided with a protrusion 346. Surface treatments such as roughening, dimple processing, and coating with a thickener may also be performed. The circuit body 400 may also have different surface treatments depending on the location of the fixing member 341.

[0070] The necessity of the surface treatment shown in Modification 5 is described below. In order to ensure the reliability of heat dissipation when fixing the cooling member 340 and the semiconductor module 300, for example, when fixing with a screw having a diameter φ of 4 mm of the fixing portion 342, an axial force of about 1200 N is applied to the sealing material 360, and when the diameter φ is 5 mm, a pressure of about 2000 N is applied. This is a large force. For example, by fixing the surface and back of the semiconductor module 300 with a fixing member 341, an axial force for fixing the surface of the semiconductor module 300 and an axial force for fixing the back of the semiconductor module 300 are applied to the fixing member 341, thereby suppressing excessive stress on the sealing material 360. However, during the installation process, force may sometimes be applied to the sealing material 360. In Modification 5, as described above, surface treatment for adhesion to the sealing material 360 is performed. This improves the adhesive force between the sealing material 360 and the buried portion 344 , and even when the cooling member 340 and the semiconductor module 300 are fixed with a strong force, high reliability can be maintained.

[0071] Figure 17 FIG. 1 is a semi-transparent top view of a semiconductor module 300 according to a sixth modification. Figure 5 The same parts are denoted by the same symbols and their descriptions are simplified.

[0072] exist Figure 5 , an example is shown in which fixing members 341 are provided at four corners of the semiconductor module 300. Figure 17 In the sixth variation shown, a fixing member 341 is also provided in the center of the semiconductor module 300. Specifically, the insulating sheets 440-1 and 440-2 are separated on the upper arm side and the lower arm side, and the fixing member 341 is also provided in the center. The reason for separating the insulating sheets 440-1 and 440-2 is to ensure that the blank portion 343 of the fixing member 341 provided in the center is in close contact with the periphery of the opening of the recess 604 of the mold 603 during the transfer molding process. In addition, an example in which one fixing member 341 is provided in the center of the semiconductor module 300 is described, but a plurality of fixing members 341 may be provided in the center, or they may be provided in other locations such as the center of the four sides of the semiconductor module 300.

[0073] According to the sixth modification, the cooling member 340 and the semiconductor module 300 can be fixed evenly with a strong force, thereby achieving an effect of excellent reliability.

[0074] Figure 18 2 is a circuit diagram of a power conversion device 200 using a semiconductor module 300 . Power conversion device 200 includes inverter circuit units 140 and 142, an auxiliary inverter circuit unit 43, and a capacitor module 500. Inverter circuit units 140 and 142 include multiple semiconductor modules 300, which are connected to form a three-phase bridge circuit. When the current capacity is large, semiconductor modules 300 are further connected in parallel. By performing these parallel connections corresponding to the phases of the three-phase inverter circuit, it is possible to cope with the increase in current capacity. Furthermore, by connecting active elements 155 and 157 and diodes 156 and 158, which are semiconductor elements built into semiconductor modules 300, in parallel, it is also possible to cope with the increase in current capacity.

[0075] The inverter circuit unit 140 and the inverter circuit unit 142 have the same basic circuit configuration, and their control methods and operations are also 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 thereof will be omitted here.

[0076] The upper arm circuit includes an upper arm active element 155 and an upper arm diode 156, which serve as switching semiconductor elements, and the lower arm circuit includes a lower arm active element 157 and a lower arm diode 158, which serve as switching semiconductor elements. Active elements 155 and 157 perform switching operations in response to drive signals output from one or the other of the two drive circuits constituting drive circuit 174, thereby converting DC power supplied from battery 136 into three-phase AC power.

[0077] The upper arm active element 155 and the lower arm active element 157 have a collector electrode, an emitter electrode, and a gate electrode. The upper arm diode 156 and the lower arm diode 158 have two electrodes, namely, a cathode electrode and an anode electrode. Figure 8 As shown, 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. This allows current to flow from the emitter electrodes of upper-arm active element 155 and lower-arm active element 157 to the collector electrodes in the forward direction. Active elements 155 and 157 are, for example, IGBTs.

[0078] Alternatively, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) may be used as the active element. In this case, the upper arm diode 156 and the lower arm diode 158 are unnecessary.

[0079] The positive-side terminal 325P and negative-side terminal 325M of each upper and lower arm series circuit are connected to the DC terminals for connecting capacitors of capacitor module 500. 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-side terminal 325A of each semiconductor module 300. The AC-side terminal 320B of each semiconductor module 300 of each phase is connected to the AC output terminals of power conversion device 200, and the generated AC power is supplied to the stator winding of motor generator 192 or 194.

[0080] The control circuit 172 generates a timing signal for controlling the switching timing of the upper arm active element 155 and the lower arm active element 157 based on input information from a vehicle-side control device or sensor (e.g., current sensor 180). The drive circuit 174 generates a drive signal for switching the upper arm active element 155 and the lower arm active element 157 based on the timing signal output from the control circuit 172. Reference numerals 181 and 188 denote connectors.

[0081] The upper and lower arm series circuits include temperature sensors (not shown). Temperature information from the upper and lower arm series circuits is input to a microcomputer. Furthermore, voltage information on the DC positive side of the upper and lower arm series circuits is input to the microcomputer. Based on this information, the microcomputer performs overtemperature and overvoltage detection. If overtemperature or overvoltage is detected, the microcomputer stops switching all upper and lower arm active elements 155 and 157, protecting the upper and lower arm series circuits from overtemperature or overvoltage.

[0082] Figure 19 yes Figure 18 The external perspective view of the power conversion device 200 is shown. Figure 20 yes Figure 19 The power conversion device 200 is shown in a perspective view in cross section along line XV-XV.

[0083] The power conversion device 200 includes a frame 12 formed of a lower shell 11 and an upper shell 10 and formed in a roughly rectangular parallelepiped shape. A circuit body 400, a capacitor module 500, etc. are housed inside the frame 12. The circuit body 400 has a cooling flow path that flows to the cooling member 340, and a refrigerant inlet pipe 13 and a refrigerant outlet pipe 14 connected to the cooling flow path protrude from one side of the frame 12. The upper side of the lower shell 11 is open, and the upper shell 10 blocks the opening of the lower shell 11 and is installed on the lower shell 11. The upper shell 10 and the lower shell 11 are formed of aluminum alloy or the like and are sealed and fixed relative to the outside. The upper shell 10 and the lower shell 11 can also be integrated to form a structure. By making the frame 12 into a simple rectangular parallelepiped shape, it is easy to install it on a vehicle or the like, and it is also easy to produce.

[0084] 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 the connector 17. A connector 21 is provided on the surface from which the refrigerant inlet pipe 13 and the refrigerant outlet pipe 14 are led out.

[0085] like Figure 20 As shown, a circuit body 400 is housed within the housing 12. The control circuit 172 and the drive circuit 174 are arranged on the circuit body 400, and a capacitor module 500 is housed on the DC terminal side of the circuit body 400. By placing the capacitor module at the same height as the circuit body 400, the power conversion device 200 can be made thinner, increasing the flexibility of its placement in the vehicle. The AC-side terminal 325A of the circuit body 400 passes through the current sensor 180 and is connected to the connector 188. Furthermore, the positive-side terminal 325P and the negative-side terminal 325M, which serve as the DC terminals of the semiconductor module 300, are connected to the positive and negative terminals 362A and 362B of the capacitor module 500, respectively.

[0086] According to the embodiment described above, the following effects can be obtained. (1) The circuit body 400 includes: a semiconductor module 300, which is formed by sealing semiconductor elements 155, 156, 157, and 158 with a sealing material 360, and has a heat dissipation surface on at least one surface for dissipating heat generated by the semiconductor elements 155, 156, 157, and 158; a cooling member 340, which is arranged opposite to the heat dissipation surface of the semiconductor module 300 and dissipates heat generated by the semiconductor elements 155, 156, 157, and 158; and a fixing member 341 The fixing member 341 is embedded in the sealing material 360 of the semiconductor module 300 to restrict the cooling member 340 from moving away from the semiconductor module 300. The fixing member 341 is composed of a buried portion 344 embedded in the sealing material 360 and a fixing portion 342 inserted into and fixing the cooling member 340. At the junction of the buried portion 344 and the fixing portion 342, the buried portion 344 has a blank portion 343 that surrounds the outer periphery of the fixing portion 342 and is exposed from the surface of the sealing material 360. This prevents the sealing material from flowing out near the fixing member.

[0087] (2) In the method for manufacturing a circuit body 400, the circuit body 400 includes semiconductor elements 155, 156, 157, 158, a cooling member 340 for cooling the heat generated by the semiconductor elements 155, 156, 157, 158, and a fixing member 341 for fixing the cooling member 340, and the semiconductor elements 155, 156, 157, 158 and the fixing member 341 are sealed with a sealing material 360, and the fixing member 341 is composed of a buried portion 344 buried in the sealing material 360 and a fixing portion 342 inserted into the cooling member 340 and fixing the cooling member 340, The buried portion 344 has a margin 343 that surrounds the outer periphery of the fixing portion 342 and is exposed from the surface of the sealing material 360. The manufacturing method includes the following steps: placing the circuit body 310 including the semiconductor elements 155, 156, 157, and 158 and the fixing member 341 in a mold 603; closely attaching the mold 603 to the margin 343 of the fixing member 341; and then injecting the sealing material 360 into the mold 603 to manufacture the semiconductor module 300; and after the sealing material 360 is cured, fixing the cooling member 340 to the semiconductor module 300 via the fixing member 341. This prevents the sealing material from flowing out near the fixing member.

[0088] The present invention is not limited to the above-described embodiment, and other aspects that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as the characteristics of the present invention are not impaired. Explanation of symbols

[0089] 10…Upper housing; 11…Lower housing; 13…Refrigerant inlet pipe; 14…Refrigerant outlet pipe; 17, 21, 181, 182, 188…Connectors; 18…AC terminal; 43, 140, 142…Inverter circuit; 155, 156, 157, 158…Semiconductor element; 172…Control circuit; 174…Drive circuit; 180…Current sensor; 192, 194…Electric generator; 200…Power converter; 300…Semiconductor module; 310…Circuit body; 325P…Positive terminal; 325M…Negative terminal; 325A…AC Side terminal; 325C…collector detection terminal; 325L…lower arm gate terminal; 325E…emitter detection terminal; 325U…upper arm gate terminal; 340…cooling member; 341…fixing member; 342…fixing portion; 343…blank portion; 344…buried portion; 360…sealing material; 400…circuit body; 430, 431, 432, 433…conductor plate; 440…insulating sheet; 443…resin insulating layer; 444…surface conductor layer; 453…heat conducting member; 500…capacitor module; 601…transfer molding device; 602…spring; 603…mold.

Claims

1. A circuit body, characterized in that: have: A semiconductor module, wherein a semiconductor element is sealed with a sealing material and has a heat dissipation surface on at least one surface for dissipating heat generated by the semiconductor element; a cooling member disposed opposite to the heat dissipation surface of the semiconductor module and cooling heat generated by the semiconductor element; as well as a fixing member embedded in the sealing material of the semiconductor module and restricting the cooling member from moving away from the semiconductor module; The fixing member is composed of a buried portion embedded in the sealing material and a fixing portion inserted into the cooling member and fixing the cooling member. At the boundary between the buried portion and the fixing portion, the buried portion has a blank portion surrounding the outer periphery of the fixing portion and exposed from the surface of the sealing material.

2. The circuit body according to claim 1, wherein: During the process of injecting the sealing material, the mold is placed in close contact with the blank portion. The blank portion is made of a material having a lower hardness than that of the mold.

3. The circuit body according to claim 1, wherein: The blank portion and a surface of the sealing material of the semiconductor module are on the same plane.

4. The circuit body according to claim 1, wherein: The fixing portion is made of a material having a higher hardness than that of the blank portion.

5. The circuit body according to claim 1, wherein: The periphery of the buried portion is subjected to a surface treatment for adhesion with the sealing material.

6. The circuit body according to claim 1, wherein: The fixing member penetrates the semiconductor module in the thickness direction, and forms the blank portions at both ends thereof.

7. The circuit body according to any one of claims 1 to 5, wherein: The semiconductor module has the heat dissipation surfaces formed on both sides corresponding to the two sides of the semiconductor element. The cooling member is arranged on both sides of the semiconductor module. The fixing member includes the margin portion that is disposed on the both surfaces and exposed from the surface of the sealing material relative to the cooling member.

8. A power conversion device, characterized in that: A circuit body according to any one of claims 1 to 5, Converts DC power to AC power and vice versa.

9. A method for manufacturing a circuit body, characterized in that: The circuit body includes a semiconductor element, a cooling member for cooling heat generated by the semiconductor element, and a fixing member for fixing the cooling member, wherein the semiconductor element and the fixing member are sealed with a sealing material, and the fixing member is composed of a buried portion buried in the sealing material and a fixing portion inserted into the cooling member and fixing the cooling member, and at a boundary between the buried portion and the fixing portion, the buried portion has a blank portion surrounding the outer periphery of the fixing portion and exposed from the surface of the sealing material. The manufacturing method comprises: a step of placing the circuit body including the semiconductor element and the fixing member in a mold, closely contacting the mold with the blank portion of the fixing member, and injecting the sealing material into the mold to manufacture a semiconductor module; and A step of fixing the cooling member to the semiconductor module by the fixing member after the sealing material is cured.

10. The method for manufacturing a circuit body according to claim 9, wherein: In the process of manufacturing the semiconductor module, the margin portion is deformed by being clamped by the mold.

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