Power module, method for manufacturing power module, and power conversion device

Abstract

The purpose of the present invention is to provide technical features that make it possible to reduce stress that is applied to an interface between a main terminal and a mold portion in a heatsink-integrated power module when the main terminal is connected to a bus bar by means of a bolt and nut. The power module comprises a semiconductor chip, a lead frame, a module base, a main terminal, a mold portion, a base portion, a heatsink, a bus bar, and a terminal base. A recess in which a nut or the head of a bolt can be disposed is formed on the main terminal side of the terminal base. A bolt that threadably engages a nut disposed in the recess, or a nut that threadably engages a bolt disposed in the recess is disposed on the opposite side of the bus bar from the terminal base. A rotation inhibiting portion for inhibiting rotation of the nut or the head of the bolt disposed in the recess is provided on the inner surface of the recess.

Description

Power module, power module manufacturing method, and power conversion device

[0001] The present disclosure relates to a power module, a method for manufacturing a power module, and a power conversion device.

[0002] For example, Patent Document 1 discloses a heat sink-integrated power module having a power module section, a fin base, and heat dissipation fins. The power module section includes a module base, power semiconductor elements mounted on the module base, and a molded section that seals the power semiconductor elements. The fin base includes a heat dissipation diffusion section to which the heat dissipation fins are attached, and a base section formed on the heat dissipation diffusion section and to which the module base is joined. The module base is provided with a first concave-convex section, and the base section is provided with a second concave-convex section that fits with the first concave-convex section.

[0003] Patent No. 675904

[0004] When the current flowing through the power module increases, the current flowing through the main terminal also increases, causing a large temperature rise in the main terminal.To suppress the temperature rise in the main terminal, it is widely and commonly practiced to connect a bus bar (external terminal) to the main terminal.

[0005] However, when connecting the main terminal and the bus bar using bolts and nuts, stress is applied to the interface between the main terminal and the molded portion, which raises concerns about peeling and cracking at the interface.

[0006] Therefore, an object of the present disclosure is to provide a technology that can reduce the stress applied to the interface between a main terminal and a molded portion when connecting the main terminal and a bus bar using bolts and nuts in a heat sink-integrated power module.

[0007] The power module according to the present disclosure includes a semiconductor element, a frame having the semiconductor element mounted on one surface thereof, a module base having the frame disposed on one surface thereof, main terminals that are part of the frame, a molded portion that seals the semiconductor element, the frame, and the module base so that the main terminals are exposed, a base portion that is integrated with the other surface of the module base exposed from the molded portion, and a heat sink having a plurality of heat dissipation fins that protrude from the base portion on the side opposite to the module base, and a bolt fastened to a first main surface of the main terminal or a second main surface opposite to the first main surface. and a structural member fixed to the base portion of the heat sink and arranged between the main terminal or the external terminal and the base portion, wherein a recess is formed on the main terminal side of the structural member in which the head of the nut or bolt can be arranged, and on the opposite side of the structural member from the external terminal, the bolt that screws into the nut arranged in the recess or the nut that screws into the bolt arranged in the recess is arranged, and a rotation suppression portion is provided on the inner surface of the recess to suppress rotation of the head of the nut or bolt arranged in the recess.

[0008] According to the present disclosure, when a bolt or nut located on the opposite side of the structural member from the external terminal is tightened, the nut or bolt located in the recess can move toward the main terminal. Therefore, the main terminal is displaced until the bolt or nut located on the opposite side of the structural member from the external terminal comes into contact with the nut or bolt located in the recess. However, when the bolt or nut located on the opposite side of the structural member from the external terminal comes into contact with the nut or bolt located in the recess, the main terminal does not displace any further, and the nut or bolt located in the recess moves toward the main terminal. In other words, when the main terminal and external terminal are connected using the bolt and nut, the displacement applied to the main terminal is limited to the clearance between the bolt and nut.

[0009] This makes it possible to reduce the stress applied to the interface between the main terminal and the molded portion when connecting the main terminal and the external terminal using bolts and nuts in a heat sink-integrated power module.

[0010] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] 1 is a cross-sectional view of a power module according to a first embodiment; a top view of a power module according to a first embodiment; a top view of a power module according to a modification of the first embodiment; a cross-sectional view showing a connection between a main terminal and a bus bar provided in a power module according to a modification of the first embodiment; a top view of a power module according to a first embodiment; a cross-sectional view showing a connection by bolting between a main terminal and a bus bar provided in a power module according to a first embodiment; a top view showing a connection by bolting between a main terminal and a bus bar provided in a power module according to a first embodiment; a cross-sectional view showing a clearance between a main terminal provided in a power module according to a first embodiment and a terminal block; a cross-sectional view showing a connection by bolting between a main terminal and a bus bar when a clearance exists between a main terminal provided in a power module according to a first embodiment and a terminal block; a cross-sectional view showing a connection by bolting between a main terminal and a bus bar provided in a power module according to a modification of the first embodiment; a cross-sectional view showing a connection by bolting between a main terminal and a bus bar provided in a power module according to a modification of the first embodiment; FIG. 1 is a top view of a terminal block and a nut provided in a power module according to embodiment 1. FIG. 2 is a top view of a terminal block and a nut provided in a power module according to a modification of embodiment 1. FIG. 3 is a top view of a terminal block and a nut provided in a power module according to a modification of embodiment 1. FIG. 4 is a top view of a terminal block and a nut provided in a power module according to a modification of embodiment 1. FIG. 5 is a top view of a terminal block and a nut provided in a power module according to a modification of embodiment 1. FIG. 6 is a cross-sectional view showing a bolted connection between the terminal block and the heat sink provided in the power module according to embodiment 1. FIG. 7 is a top view showing a bolted connection between the terminal block and the heat sink provided in the power module according to embodiment 1. FIG. 8 is a cross-sectional view showing a soldered connection between the terminal block and the heat sink provided in the power module according to the modification of embodiment 1. FIG. 9 is a cross-sectional view showing a welded connection between the terminal block and the heat sink provided in the power module according to the modification of embodiment 1.FIG. 1 is a cross-sectional view showing a connection by crimping of a terminal block and a heat sink provided in a power module according to a modified example of embodiment 1. FIG. 2 is a cross-sectional view showing an arrangement of a terminal block having a positioning structure provided in a power module according to a modified example of embodiment 1. FIG. 3 is a cross-sectional view, a side view, and a top view showing an arrangement of a terminal block having a positioning structure provided in a power module according to a modified example of embodiment 1. FIG. 4 is a cross-sectional view of a power module according to a modified example of embodiment 1. FIG. 5 is a cross-sectional view of a power module according to a modified example of embodiment 1. FIG. 6 is a cross-sectional view of a power module according to a modified example of embodiment 1. FIG. 7 is a cross-sectional view of a power module according to a modified example of embodiment 1. FIG. 8 is a cross-sectional view of a power module according to a modified example of embodiment 2. FIG. 9 is a cross-sectional view showing a connection by bolt fastening of a main terminal and a bus bar provided in a power module according to embodiment 2. FIG. 10 is a top view of a terminal block, a nut, and a nut fall-off prevention member provided in a power module according to embodiment 2. FIG. 11 is a cross-sectional view showing a connection by bolt fastening of a main terminal and a bus bar provided in a power module according to a modified example of embodiment 2. FIG. 12 is a cross-sectional view of a power module according to embodiment 3. FIG. 13 is a cross-sectional view showing a state before bolt fastening of a main terminal and a bus bar provided in a power module according to embodiment 3. FIG. 14 is a cross-sectional view showing a connection by bolt fastening of a main terminal and a bus bar provided in a power module according to embodiment 3. Fig. 10 is a top view of a terminal block, a nut, and a nut fall-off prevention member provided in the power module according to embodiment 3. Fig. 11 is a cross-sectional view showing a state before bolt fastening between a main terminal and a bus bar provided in a power module according to a modified example of embodiment 3. Fig. 12 is a cross-sectional view showing a state before bolt fastening between a main terminal and a bus bar provided in a power module according to a modified example of embodiment 3. Fig. 13 is a block diagram showing the configuration of a power conversion system to which a power conversion device according to embodiment 4 is applied.

[0012] First Embodiment A first embodiment will be described below with reference to the drawings. Fig. 1 is a cross-sectional view of a power module 202 according to the first embodiment. Fig. 2 is a top view of the power module 202 according to the first embodiment.

[0013] 1 and 2, the power module 202 is a heat sink-integrated power module, and includes a power module section 9 and a heat sink 16. The power module section 9 includes a plurality of semiconductor chips 1 (semiconductor elements), a lead frame 3 (frame), an insulating sheet 4, a module base 5, a molded section 8, and a plurality of bus bars 10 (external terminals). A terminal block is disposed on the heat sink 16. The terminal block is characterized in that the nut is prevented from rotating and is mounted in a state in which it can move between the main terminal 7 side and the heat sink 16 side.

[0014] A plurality of semiconductor chips 1 are mounted on the upper surface (one surface) of a lead frame 3. The lead frame 3 is arranged via an insulating sheet 4 that is attached to the upper surface (one surface) of a module base 5. A molded portion 8 is made of a resin-based material, and seals the semiconductor chips 1, lead frame 3, insulating sheet 4, and module base 5 so that main terminals 7, which are part of the lead frame 3, and the lower surface (other surface) of the module base 5 are exposed.

[0015] The heat sink 16 has a base portion 14 integrated with the lower surface (other surface) of the module base 5, and a plurality of heat dissipation fins 15 protruding downward from the base portion 14 (opposite the module base 5). A plurality of concave mating portions 5a are provided on the lower surface (other surface) of the module base 5. Furthermore, a plurality of convex mated portions 14a that can be mated with the mating portions 5a are provided on the upper surface (the surface facing the module base 5) of the base portion 14. The module base 5 and the heat sink 16 are integrated by mating the mating portions 5a with the mated portions 14a. The mating portions 5a and the mated portions 14a may be provided continuously or intermittently in the depth direction of the module base 5 and the base portion 14, respectively. Furthermore, the unevenness of the mating portion 5a of the module base 5 and the mated portion 14a of the base portion 14 of the heat sink 16 is not limited to this, and the same effect can be achieved even if the mating portion 5a of the module base 5 is convex or the mated portion 14a of the base portion 14 of the heat sink 16 is concave.

[0016] The heat sink 16 is formed in a rectangular shape when viewed from above. Two terminal blocks 13 (structural members) are fixed to both ends of a base portion 14 of the heat sink 16. Each terminal block 13 is disposed between the main terminal 7 and the base portion 14.

[0017] After molding, molding is performed to form terminals, thereby forming the control terminals 6 and main terminals 7 that are part of the lead frame 3. However, molding to form the terminals is not essential and can be omitted.

[0018] Next, the main terminals 7 and the control terminals 6 will be described. The main terminals 7 and the control terminals 6 are part of the lead frame 3, and are connected to the semiconductor chip 1 inside the molded portion 8 by wiring members (not shown) such as aluminum wires. However, the wiring members do not necessarily have to be aluminum wires, and may be metal wires such as copper wires, or metal plates using joining members such as solder for electrical connection. The main terminals 7 and the control terminals 6 are integrated by molding while being exposed from the molded portion 8.

[0019] The multiple (four) main terminals 7 extend in the left-right direction (first direction) that is parallel to the base portion 14 of the heat sink 16, and are exposed from the molded portion 8. Specifically, two of the main terminals 7 are formed linearly so as to extend leftward from the left end of the molded portion 8, and the remaining two main terminals 7 are formed linearly so as to extend rightward from the right end of the molded portion 8. The lower surfaces (second main surfaces) of the main terminals 7 face the heat sink 16, and the upper surfaces (first main surfaces) of the main terminals 7 face upward (the side opposite to the heat sink 16).

[0020] Here, when a large current flows through the power module 202, the thickness of the lead frame 3 including the main terminals 7 and the control terminals 6 is often increased from the viewpoint of current density. Therefore, when a thick lead frame 3 is bent by terminal formation processing, the press tonnage increases, which raises concerns about an increase in the size of the equipment and a decrease in productivity.

[0021] In the first embodiment, as described above, the lower surface (second main surface) of the main terminal 7 faces the heat sink 16, and the upper surface (first main surface) of the main terminal 7 faces upward (the side opposite to the heat sink 16). In other words, the main terminal 7, which has a large terminal cross-sectional area, is formed to extend horizontally relative to the molded portion 8, thereby eliminating the need for terminal formation processing on the upper and lower surfaces of the main terminal 7. Since only the control terminal 6, which has a small terminal cross-sectional area, is formed and processed as needed, there is no need to increase the size of the equipment, improving productivity.

[0022] Furthermore, since the terminal forming process of the main terminals 7 is not required, there is no need to increase the length of the main terminals 7 for terminal formation, and the length can be shortened. The shorter length of the main terminals 7 allows the area of ​​the lead frame 3, including the main terminals 7, to be reduced accordingly. This makes it possible to cut out multiple shapes from one lead frame (multiple cutting), thereby improving productivity. Alternatively, the shorter length of the main terminals 7 allows the area of ​​the lead frame 3 in the power module 202 to be increased while keeping the area of ​​the lead frame 3, including the main terminals 7, unchanged. This allows for greater freedom in designing the layout of the semiconductor chip 1 and the electrical wiring, and improved heat dissipation.

[0023] 3( a ) and 3 ( b ) are top views of a power module 202 according to a modification of the first embodiment. As shown in FIG. 3( a ), the main terminal 7 may be L-shaped in top view, or as shown in FIG. 3( b ), the main terminal 7 may be U-shaped in top view. However, the shape of the main terminal 7 is not limited to this and can be freely designed. By using such a shape, it is possible to reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when the main terminal 7 is connected to the bus bar 10. Furthermore, it is also possible to reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when vibrations occur during product use, thereby improving the vibration resistance of the product.

[0024] 4 is a cross-sectional view showing a connection between a main terminal 7 and a bus bar 10 included in a power module 202 according to a modification of the first embodiment. As shown in FIG. 4 , the main terminal 7 may have a crank shape in cross section. Specifically, the main terminal 7 has a first parallel portion 7a exposed from the molded portion 8 in a first direction parallel to the base portion 14 of the heat sink 16, a first vertical portion 7b extending from the first parallel portion 7a in a second direction perpendicular to the first parallel portion 7a, and a second parallel portion 7c extending from the first vertical portion 7b in the first direction. The bus bar 10 is connected to a first main surface of the second parallel portion 7c of the main terminal 7.

[0025] As shown in Fig. 4 , by bending the main terminal 7 during terminal formation, the bent portion has elasticity, which can reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when the main terminal 7 is connected to the busbar 10. Similarly, it can also reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when vibrations occur during product use, improving the vibration resistance of the product. Note that although the shape of the main terminal 7 shown in Fig. 4 requires bending, the second parallel portion 7c extends horizontally, which makes it possible to stably connect, for example, one large-area busbar 10 to two main terminals 7.

[0026] Here, as shown in FIG. 2 , the power module 202 according to the first embodiment has a structure in which, in a top view, the main terminals 7 are arranged on two sides of the molded portion 8 and the control terminals 6 are arranged on the other two sides. However, the arrangement of the main terminals 7 and the control terminals 6 is not limited to this. FIGS. 5 and 6 are top views of the power module 202 according to a modification of the first embodiment. As shown in FIG. 5 , the main terminals 7 may be arranged on one side and the control terminals 6 on the other two sides, or as shown in FIG. 6 , the main terminals 7 and the control terminals 6 may be arranged together on one side, allowing for flexible design. In this way, arranging the main terminals 7 and the control terminals 6 on multiple sides of the power module 202 has the advantage of increasing the degree of freedom in designing the electrical wiring (e.g., aluminum wire) within the power module 202.

[0027] Fig. 7 is a cross-sectional view showing the bolted connection between the main terminal 7 and the bus bar 10 included in the power module 202 according to the first embodiment. Fig. 8 is a top view showing the bolted connection between the main terminal 7 and the bus bar 10 included in the power module 202 according to the first embodiment. Fig. 9 is a cross-sectional view showing the clearance 18 between the main terminal 7 and the terminal block 13 included in the power module 202 according to the first embodiment. Fig. 10 is a cross-sectional view showing the bolted connection between the main terminal 7 and the bus bar 10 when the clearance 18 exists between the main terminal 7 and the terminal block 13 included in the power module 202 according to the first embodiment.

[0028] As shown in Fig. 7, the easiest and most productive method for connecting the main terminal 7 and the bus bar 10 is to fasten them together using bolts 11 and nuts 12. The bolt fastening method will now be described.

[0029] A recess 17 is formed in the upper portion of each terminal block 13 (on the main terminal 7 side of each terminal block 13) in which the head of a nut 12 or a bolt 11 can be placed. The recess 17 has a first recess 17a and a second recess 17b. The first recess 17a constitutes the upper portion of the recess 17. The second recess 17b is formed below the first recess 17a (on the heat sink 16 side) and constitutes the lower portion of the recess 17. The first recess 17a and the second recess 17b are connected to each other, and the outline of the first recess 17a is larger than that of the second recess 17b when viewed from above (on the main terminal 7 side).

[0030] Specifically, first recess 17a is formed to a size that allows the placement of nut 12 and the head of bolt 11. Second recess 17b is formed to a size that allows the shank of bolt 11 that screws into nut 12 placed in first recess 17a to be accommodated. An inner surface of first recess 17a is provided with a rotation suppressing portion that suppresses rotation of the head of nut 12 or bolt 11 placed in first recess 17a.

[0031] 8 , a cutout 7d is formed in the main terminal 7, and a cutout 10a is formed in the bus bar 10 at a position corresponding to the cutout 7d. The main terminal 7 and the bus bar 10 are fastened together by fastening a nut 12 to the shank of the bolt 11 with the shank of the bolt 11 inserted through the cutout 10a and the cutout 7d.

[0032] Due to tolerances of each component and warping of the molded portion 8, the heightwise positional relationship between the main terminal 7 and the terminal block 13 does not necessarily result in a zero clearance 18, as shown in Fig. 9. In other words, as shown in Fig. 9, either a clearance 18 exists between the main terminal 7 and the terminal block 13, or the main terminal 7 and the terminal block 13 interfere with each other. If the clearance 18 between the main terminal 7 and the terminal block 13 is large, a large displacement is applied to the main terminal 7 and the bus bar 10 when connecting the main terminal 7 and the bus bar 10.

[0033] For this reason, there is a concern that a large stress will be applied to the interface between the molded portion 8 and the main terminal 7 when the bolt is tightened, causing separation and cracks at the interface, as shown in Fig. 10. However, in the first embodiment, rotation of the nut 12 is suppressed and the nut 12 is arranged in a state in which it can move toward the main terminal 7 and the heat sink 16, so that the nut 12 can move toward the main terminal 7 when the bolt is tightened, as shown in Fig. 7.

[0034] Therefore, when connecting the main terminal 7 and the bus bar 10 by fastening the bolts, the main terminal 7 is displaced until the bolt 11 contacts the nut 12, but once the bolt 11 contacts the nut 12, the displacement of the main terminal 7 does not change any further and the nut 12 moves toward the main terminal 7. In other words, when connecting the main terminal 7 and the bus bar 10 by fastening the bolts, the displacement applied to the main terminal 7 is limited to the clearance 18 between the bolt 11 and the nut 12, not the clearance 18 between the main terminal 7 and the terminal block 13. Therefore, in the first embodiment, the stress applied to the interface between the molded portion 8 and the main terminal 7 is reduced, and the main terminal 7 and the bus bar 10 can be connected with good productivity.

[0035] 11, 12(a), 12(b), and 13 are cross-sectional views showing the connection by bolt fastening between the main terminal 7 and the bus bar 10 provided in a power module 202 according to a modification of the first embodiment.

[0036] 7, the busbar 10 may be disposed above the main terminal 7 (opposite the heat sink 16), with the bolts 11 disposed above the busbar 10 and the terminal blocks 13 and nuts 12 disposed below the main terminal 7 (towards the heat sink 16), and the connection may be made by fastening the bolts. Alternatively, as shown in FIG. 11, the busbar 10 may be disposed below the main terminal 7, with the bolts 11 disposed above the main terminal 7 and the terminal blocks 13 and nuts 12 disposed below the busbar 10, and the connection may be made by fastening the bolts.

[0037] 12(a) and 12(b), it is also possible to interchange the bolt 11 and nut 12 in each arrangement, with the nut 12 on the upper side and the terminal block 13 and bolt 11 on the lower side, and connect them by fastening the bolt. When the terminal block 13 and bolt 11 are arranged on the lower side and fastened with the bolt, the bolt 11 is arranged on the terminal block 13 in a state where it can move toward the main terminal 7 and the heat sink 16, and the bolt 11 moves toward the main terminal 7 by rotating the nut 12. In this arrangement, the shaft of the bolt 11 can also serve to position the main terminal 7 and the bus bar 10.

[0038] In the structure shown in Fig. 7, the second recess 17b of the terminal block 13 functions as a recess for the bolt 11. However, as shown in Fig. 13, if the bolt 11 and the terminal block 13 do not interfere with each other, the second recess 17b functioning as a recess for the bolt 11 is unnecessary, and only the first recess 17a is required. Also, as shown in Figs. 12(a) and 12(b), the second recess 17b is unnecessary when the head of the bolt 11 is placed in the recess 17 of the terminal block 13.

[0039] Next, a description will be given of a rotation suppressing section that suppresses rotation of the head of the nut 12 or bolt 11 arranged in the recess 17. Fig. 14 is a top view of the terminal block 13 and the nut 12 provided in the power module 202 according to the first embodiment. Figs. 15 to 18 are top views of the terminal block 13 and the nut 12 provided in the power module 202 according to modifications of the first embodiment.

[0040] As shown in FIGS. 7 and 14 , the terminal block 13 has a recess 17 (specifically, a first recess 17a) that is hexagonal in top view (viewed from the main terminal 7 side). A nut 12 that is hexagonal in top view is disposed in the recess 17. The nut 12 is prevented from rotating and is movable toward the main terminal 7 side and the heat sink 16 side. To prevent rotation of the nut 12, the minimum width of the recess 17 must be smaller than the maximum width of the nut 12. Here, the minimum width of the recess 17 is the minimum distance between opposing sides of the hexagonal recess 17, i.e., the diameter of the inscribed circle of the hexagonal recess 17. The maximum width of the nut 12 is the maximum distance between opposing corners of the hexagonal nut 12, i.e., the diameter of the circumscribed circle of the hexagonal nut 12.

[0041] When the head of bolt 11 is placed in recess 17, the minimum width of recess 17 must be smaller than the maximum width of the head of bolt 11 in order to prevent rotation of bolt 11. Here, the rotation prevention portion that prevents rotation of the head of nut 12 or bolt 11 placed in recess 17 is configured based on the relationship between the minimum width of recess 17 and the maximum width of the head of nut 12 and bolt 11.

[0042] However, the structure of the terminal block 13 and the nut 12 is not limited to the structure shown in FIG. 14 . For example, as shown in FIGS. 15( a) and 15(b), at least one protrusion 19 protruding inward may be formed on the inner surface of the recess 17. In this structure, as shown in FIGS. 16(a) and 16(b), the tightening torque of the bolt 11 when connecting the bus bar damages at least one protrusion 19, eliminating the rotation suppressing effect of the nut 12 and allowing the nut 12 to move toward the main terminal 7 and the heat sink 16. With this structure, the nut 12 is placed in the recess 17 of the terminal block 13 during fabrication, and the terminal block 13 can be transported without the nut 12 falling off. This eliminates the need to place the nut 12 on the terminal block 13 during assembly of the power module 202, improving productivity.

[0043] The shape of the protrusion 19 does not have to be round as shown in Figures 15 and 16, and may be any shape, such as a square or triangle. Alternatively, as shown in Figure 17, a recess 17 may be formed to interfere with the nut 12, and the nut 12 may be press-fitted into the recess 17. In this structure, by adjusting the amount of interference between the recess 17 and the nut 12, the nut 12 will not fall off due to vibrations during transportation. Furthermore, the fastening torque of the bolt 11 when connecting the busbar allows the press-fitted nut 12 to come out of the recess 17 of the terminal block 13 and move toward the main terminal 7. In this case, the entire recess 17 may interfere with the nut 12, as shown in Figure 17, or only a portion of the recess 17 may interfere with the nut 12, as shown in Figures 18(a), 18(b), and 18(c).

[0044] Fig. 19 is a cross-sectional view showing the connection by bolt fastening between the terminal block 13 and the heat sink 16 included in the power module 202 according to the first embodiment. Fig. 20 is a top view showing the connection by bolt fastening between the terminal block 13 and the heat sink 16 included in the power module 202 according to the first embodiment. Fig. 21 is a cross-sectional view showing the connection by solder 2 between the terminal block 13 and the heat sink 16 included in the power module 202 according to a modification of the first embodiment. Fig. 22 is a cross-sectional view showing the connection by welding between the terminal block 13 and the heat sink 16 included in the power module 202 according to a modification of the first embodiment. Fig. 23 is a cross-sectional view showing the connection by crimping between the terminal block 13 and the heat sink 16 included in the power module 202 according to the modification of the first embodiment.

[0045] The connection between the terminal block 13 and the base portion 14 of the heat sink 16 may be made by any of the following connection methods: bolt fastening as shown in Figures 19 and 20, connection using a joining material such as solder 2 as shown in Figure 21, connection by welding as shown in Figure 22, or connection by crimping as shown in Figure 23. Note that reference numeral 20 in Figure 22 indicates a welded portion, and reference numeral 20a in Figure 23 indicates a crimped portion.

[0046] 19 to 23, the terminal block 13 is connected to the base portion 14 of the heat sink 16, but this is not limited thereto, and for example, as shown in Fig. 24, a positioning groove 22a may be provided in the base portion 14 of the heat sink 16, and a convex positioning portion 22 that can fit into the groove 22a may be provided on the terminal block 13, thereby fixing the terminal block 13 to the base portion 14 of the heat sink 16. In this way, the process of attaching the terminal block 13 can be simplified and productivity can be improved.

[0047] 25(a) and 25(b) are cross-sectional views showing the arrangement of terminal blocks 13 having a positioning structure provided in a power module 202 according to a modification of embodiment 1, while Fig. 25(c) is a side view. Also, Figs. 25(d) and 25(e) are top views showing the arrangement of terminal blocks 13 having a positioning structure provided in a power module 202 according to a modification of embodiment 1.

[0048] The positioning portion of the terminal block 13 is not limited to the structure shown in FIG. 24 . Any structure capable of determining the position of the terminal block 13 in at least one direction, such as those shown in FIGS. 25( a) to 25(e), may be used. Specifically, as shown in FIG. 25(a), a positioning groove 22a may be provided in the terminal block 13, and a T-shaped positioning portion 22 in cross section may be provided in the base portion 14. Alternatively, as shown in FIG. 25(b), the entire lower end of the terminal block 13 may be used as the positioning portion, and a groove 22a into which the positioning portion can fit may be provided in the base portion 14. Alternatively, as shown in FIG. 25(c), two convex positioning portions 22 may be provided in the base portion 14, and two grooves 22a may be provided in the terminal block 13. Alternatively, as shown in FIG. 25(d), the positioning portion 22 provided in the base portion 14 may have a shape similar to two connected crosses when viewed from above. 25( e), both of the positioning portions 22 provided on the base portion 14 may be cylindrical. Note that, with the terminal block 13 positioned by the positioning portions 22, it is also possible to fix the terminal block 13 to the heat sink 16 by a combination of methods, such as bolt fastening.

[0049] 26 to 28 are cross-sectional views of a power module 202 according to a modification of the first embodiment. FIG. 1 shows an example in which a crimped heat sink is used as the heat sink 16, in which a base portion 14 and a plurality of heat dissipation fins 15 are integrated by crimping. The base portion 14 is processed by machining, die-casting, forging, extrusion, or the like, and is made of aluminum or an aluminum alloy. By using a plate material such as aluminum or an aluminum alloy for the heat dissipation fins 15, it is possible to achieve both workability and heat dissipation properties.

[0050] However, the materials for the base 14 and the heat dissipation fins 15 are not limited to aluminum, and may be a combination of different materials. For example, from the viewpoint of heat dissipation capacity, using a copper-based plate material, which has a higher thermal conductivity than aluminum-based materials, for the heat dissipation fins 15 will further improve heat dissipation capacity compared to aluminum-based materials. Furthermore, the heat sink 16 is not limited to the crimped heat sink shown in Fig. 1, and may be an extruded heat sink manufactured by extrusion as shown in Fig. 26, a machined heat sink manufactured by cutting, or a forged heat sink manufactured by forging, or a die-cast heat sink manufactured by die-casting as shown in Fig. 27.

[0051] A mating portion 5a is provided on the lower surface (the other surface) of the module base 5, and a mated portion 14a that can be mated with the mating portion 5a is provided on the upper surface (the surface facing the module base 5) of the base portion 14 of the heat sink 16, and the module base 5 and the heat sink 16 are integrated by mating the mating portion 5a with the mated portion 14a. Therefore, the module base 5 and the heat sink 16 can be integrated in a room temperature process, and the equipment for integration does not become large and complicated, thereby improving productivity.

[0052] However, as shown in Figure 28, the module base 5 and heat sink 16 may be integrated using a bonding material such as solder 2. It is also possible to integrate the module base 5 and heat sink 16 using a combination of methods, such as using caulking and a bonding material. The module base 5 is processed by machining, die-casting, forging, extrusion, or the like, and is made of aluminum or an aluminum alloy. However, the material of the module base 5 is not limited to aluminum; using a copper-based plate material, which has a higher thermal conductivity than aluminum-based materials, will further improve heat dissipation capabilities compared to aluminum-based materials.

[0053] The semiconductor chip 1 may be made of silicon or a wide bandgap semiconductor such as silicon carbide or gallium nitride.

[0054] The lead frame 3 and the bus bar 10 are preferably made of a copper-based material or an aluminum-based material from the viewpoint of electrical resistivity and workability, but any metal material may be used.

[0055] The terminal block 13 is made of resin from the viewpoint of workability and insulation. However, the terminal block 13 does not necessarily have to be made of resin and may be made of a metal material. If it is necessary to ensure an insulation distance between the lead frame 3 and the heat sink 16 and between the lead frame 3 and the nut 12, the terminal block 13 may be made of a composite material in which a metal material is covered with a resin material.

[0056] <Effects> As described above, in the first embodiment and its modifications, the power module 202 includes: the semiconductor chip 1; the lead frame 3 having the semiconductor chip 1 mounted on one surface thereof; the module base 5 having the lead frame 3 arranged on one surface thereof; the main terminals 7 that are part of the lead frame 3; the molded portion 8 that seals the semiconductor chip 1, the lead frame 3, and the module base 5 so that the main terminals 7 are exposed; the base portion 14 that is integrated with the other surface of the module base 5 exposed from the molded portion 8; the heat sink 16 that has a plurality of heat dissipation fins 15 that protrude from the base portion 14 on the side opposite to the module base 5; the bus bar 10 that is connected by the bolts 11 and the nuts 12 to the first main surfaces of the main terminals 7 or the second main surfaces opposite to the first main surfaces; and the terminal block 13 that is fixed to the base portion 14 of the heat sink 16 and is arranged between the main terminals 7 or the bus bar 10 and the base portion 14. A recess 17 is formed on the main terminal 7 side of the terminal block 13, in which the head of a nut 12 or a bolt 11 can be placed, and on the opposite side of the terminal block 13 with respect to the bus bar 10, a bolt 11 that screws into the nut 12 placed in the recess 17, or a nut 12 that screws into the bolt 11 placed in the recess 17, is placed, and a rotation suppression portion is provided on the inner surface of the recess 17 to suppress rotation of the head of the nut 12 or bolt 11 placed in the recess 17.

[0057] Specifically, the recess 17, the nut 12, and the head of the bolt 11 are formed in a hexagonal shape when viewed from the main terminal 7 side, the minimum width of the recess 17 is smaller than the maximum width of the head of the nut 12 and the bolt 11, and the rotation suppression portion is configured based on the relationship between the minimum width of the recess 17 and the maximum width of the head of the nut 12 and the bolt 11.

[0058] The manufacturing method of the power module 202 also includes the steps of: (a) arranging the head of a nut 12 or a bolt 11 in the recess 17 with the busbar 10 placed on the first or second main surface of the main terminal 7; and (b) rotating the bolt 11 or nut 12 placed on the opposite side of the terminal block 13 with respect to the busbar 10 to screw into the nut 12 or the bolt 11 placed in the recess 17, thereby connecting the busbar 10 and the main terminal 7.

[0059] Therefore, when the bolt 11 or nut 12 arranged on the opposite side of the terminal block 13 with respect to the bus bar 10 is fastened, the nut 12 or bolt 11 arranged in the recess 17 can move toward the main terminal 7. For this reason, the main terminal 7 is displaced until the bolt 11 or nut 12 arranged on the opposite side of the terminal block 13 with respect to the bus bar 10 comes into contact with the nut 12 or bolt 11 arranged in the recess 17, but when the bolt 11 or nut 12 arranged on the opposite side of the terminal block 13 with respect to the bus bar 10 comes into contact with the nut 12 or bolt 11 arranged in the recess 17, the main terminal 7 does not displace any further, and the nut 12 or bolt 11 arranged in the recess 17 moves toward the main terminal 7. In other words, the displacement applied to the main terminal 7 when the main terminal 7 and the bus bar 10 are connected using the bolt 11 and nut 12 is limited to the clearance 18 between the bolt 11 and the nut 12.

[0060] This reduces the stress applied to the interface between the main terminal 7 and the molded portion 8 when connecting the main terminal 7 and the bus bar 10 using the bolt 11 and nut 12 in the heat sink-integrated power module 202.

[0061] In addition, the recess 17 has a first recess 17a and a second recess 17b formed closer to the heat sink 16 than the first recess 17a, the first recess 17a and the second recess 17b are connected, and the first recess 17a has a larger outline when viewed from the main terminal 7 side than the second recess 17b.

[0062] Therefore, the second recess 17b, which has a smaller outer size than the first recess 17a, functions as a recess for the shaft of the bolt 11, allowing the main terminal 7 and the bus bar 10 to be connected easily and with good productivity.

[0063] The main terminals 7 extend in a first direction parallel to the base portion 14 of the heat sink 16 and are exposed from the molded portion 8 .

[0064] Therefore, terminal formation processing of the main terminals 7 is not required, and productivity can be improved. Furthermore, because terminal formation processing of the main terminals 7 is not required, the main terminals 7 can be shortened. The area of ​​the lead frame 3 including the main terminals 7 can be reduced by the amount corresponding to the shortened length of the main terminals 7. Alternatively, the area of ​​the lead frame 3 including the main terminals 7 can be increased by the amount corresponding to the shortened length of the main terminals 7, while keeping the area of ​​the lead frame 3 including the main terminals 7 the same.

[0065] The main terminal 7 also has a first parallel portion 7a exposed from the molded portion 8 in a first direction that is parallel to the base portion 14 of the heat sink 16, a first vertical portion 7b extending from the first parallel portion 7a in a second direction that is vertical, and a second parallel portion 7c extending from the first vertical portion 7b in the first direction, and the bus bar 10 is connected to the second parallel portion 7c of the main terminal 7.

[0066] Therefore, it is possible to reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when connecting the main terminal 7 and the bus bar 10. Similarly, it is also possible to reduce the stress applied to the interface between the main terminal 7 and the molded portion 8 when vibrations occur during product use, thereby improving the vibration resistance of the product.

[0067] In addition, at least one protrusion 19 is formed on the inner surface of the recess 17. Therefore, the nut 12 is placed in the recess 17 of the terminal block 13 when the terminal block 13 is manufactured, and the terminal block 13 can be transported without the nut 12 falling off, eliminating the need to place the nut 12 in the recess 17 of the terminal block 13 when assembling the power module 202, thereby improving productivity.

[0068] In addition, a mating portion 5a is provided on the other side of the module base 5, and a mated portion 14a that can be mated with the mating portion 5a is provided on the surface of the base portion 14 of the heat sink 16 facing the module base 5, and the module base 5 and the heat sink 16 are integrated by mating the mating portion 5a with the mated portion 14a.

[0069] Therefore, integration can be achieved in a room temperature process, and the equipment does not become large and complicated, thereby improving productivity.

[0070] <Embodiment 2> Next, a power module 202 according to embodiment 2 will be described. Fig. 29 is a cross-sectional view of the power module 202 according to embodiment 2. Fig. 30 is a cross-sectional view showing the connection by bolt fastening between the main terminals 7 and the bus bars 10 provided in the power module 202 according to embodiment 2. Fig. 31 is a top view of the terminal block 13, the nuts 12, and the nut fall-off prevention members 25 provided in the power module 202 according to embodiment 2. Fig. 32 is a cross-sectional view showing the connection by bolt fastening between the main terminals 7 and the bus bars 10 provided in a power module 202 according to a modification of embodiment 2. Note that in embodiment 2, the same components as those described in embodiment 1 are designated by the same reference numerals, and description thereof will be omitted.

[0071] As shown in FIG. 29, in the second embodiment, the power module 202 further includes a nut fall-off prevention member 25 (second structural member) in addition to the components in the first embodiment.

[0072] 30 and 31 , the nut fall-off prevention member 25 is formed in a U-shape in cross section and is attached so as to be movable toward the main terminal 7 and the heat sink 16 relative to the terminal block 13 and not to fall off in either direction. Specifically, the nut fall-off prevention member 25 is disposed between the main terminal 7 and the nut 12 and is attached by engagement below the recess 17 inside the terminal block 13 (toward the heat sink 16). Both ends of the U-shape of the nut fall-off prevention member 25 face inward and face each other, and engage with an internal space 13b provided below the recess 17 inside the terminal block 13.

[0073] Here, the movable range of the nut fall-off prevention member 25 toward the main terminal 7 needs to be within a range that prevents the nut 12 from falling off. When the main terminal 7 and the bus bar 10 are connected by fastening a bolt, the nut 12 moves toward the main terminal 7. At that time, the nut 12 presses the nut fall-off prevention member 25, so that the nut fall-off prevention member 25 moves toward the main terminal 7 together with the nut 12.

[0074] The material of the nut fall-off prevention member 25 may be any material, such as resin or metal. The nut fall-off prevention member 25 is not limited to the structure shown in Fig. 30. For example, as shown in Fig. 32, the U-shaped ends of the nut fall-off prevention member 25 may face outward and upward so that they face in opposite directions. As such, any structure may be used as long as the nut fall-off prevention member 25 and the nut 12 do not fall off from the terminal block 13 and the nut fall-off prevention member 25 and the nut 12 can move toward the main terminal 7 and the heat sink 16.

[0075] <Effects> As described above, in the second embodiment and its modified example, the bus bar 10 is connected to the first main surface of the main terminal 7 by the bolt 11 and the nut 12, and the power module 202 is further provided with the nut fall-off prevention member 25 that is disposed between the main terminal 7 and the nut 12 and attached to the inside of the terminal block 13 closer to the heat sink 16 than the recess 17.

[0076] The manufacturing method of the power module 202 also includes the steps of: (a) arranging a busbar 10 on the first main surface of the main terminal 7, and then arranging a bolt 11 on the opposite side of the busbar 10 from the terminal block 13 to screw into a nut 12 previously placed in the recess 17; and (b) connecting the busbar 10 and the main terminal 7 by rotating the bolt 11 placed on the opposite side of the busbar 10 from the terminal block 13 to screw into the nut 12 placed in the recess 17.

[0077] Therefore, the nut anti-fall-off member 25 allows the terminal block 13 to be transported without the nut 12 falling off, eliminating the need to place the nut 12 on the terminal block 13 when assembling the power module 202, thereby improving productivity.

[0078] Third Embodiment Next, a power module 202 according to the third embodiment will be described. FIG. 33 is a cross-sectional view of the power module 202 according to the third embodiment. FIG. 34 is a cross-sectional view showing a state before the main terminals 7 and busbars 10 included in the power module 202 according to the third embodiment are fastened with bolts. FIG. 35 is a cross-sectional view showing the connection by bolt fastening of the main terminals 7 and busbars 10 included in the power module 202 according to the third embodiment. FIG. 36 is a top view of the terminal block 13, nuts 12, and nut fall-off prevention members 26 included in the power module 202 according to the third embodiment. FIG. 37 is a cross-sectional view showing a state before the main terminals 7 and busbars 10 included in the power module 202 according to the third embodiment are fastened with bolts. FIG. 38 is a cross-sectional view showing a state before the main terminals 7 and busbars 10 included in the power module 202 according to the third embodiment are fastened with bolts. In the third embodiment, the same components as those described in the first and second embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0079] As shown in FIG. 33, in the third embodiment, the power module 202 further includes a nut fall-off prevention member 26 (second structural member) in addition to the components in the first embodiment.

[0080] 33 to 36, the nut fall-off prevention member 26 is formed in an L-shape in cross section and is fixed to the terminal block 13. The nut fall-off prevention member 26 has less rigidity and is flexible than the main terminal 7. The nut fall-off prevention member 26 may be made of any metal as long as it is flexible. One end of the nut fall-off prevention member 26 is disposed between the main terminal 7 and the nut 12, and the other end of the nut fall-off prevention member 26 is fixed below the recess 17 inside the terminal block 13 (toward the heat sink 16).

[0081] With this structure, the nuts 12 can be placed when the terminal block 13 is manufactured and can be transported without falling off, eliminating the need to place the nuts 12 on the terminal block 13 when assembling the power module 202, improving productivity. Furthermore, when the bolts are fastened, the flexible nut fall-off prevention member 26 deforms, causing the nuts 12 to move toward the main terminals 7, as shown in Figure 35. Because the nut fall-off prevention member 26 fixed to the terminal block 13 is fastened with the bolts together with the bus bars 10 and the main terminals 7, the vibration resistance of the assembled product is improved.

[0082] The nut fall-prevention member 26 may be fixed to the terminal block 13 by any of the following methods: insert-molding the nut fall-prevention member 26 when molding the terminal block 13; press-fitting the nut fall-prevention member 26 after molding the terminal block 13; fixing the nut fall-prevention member 26 to the terminal block 13 using a bolt; or joining the nut fall-prevention member 26 to the terminal block 13 using a bonding material.

[0083] The nut fall-off prevention member 26 is not limited to the structure shown in Figures 34 and 35, i.e., a structure covering the outer surface of the nut 12, but may also be a structure covering other surfaces of the side of the nut 12, or a structure fixed to the outer surface of the terminal block 13 as shown in Figure 37.

[0084] 38, a U-shaped portion 27 may be provided at the bent portion of the nut fall-off prevention member 26, and the shape of the nut fall-off prevention member 26 can be designed freely. By shaping the nut fall-off prevention member 26 as shown in FIG. 38, it is possible to increase the flexibility of the nut fall-off prevention member 26. Also, in FIGS. 34 and 35, the nut fall-off prevention member 26 is fixed to the terminal block 13 at one point, but the nut fall-off prevention member 26 may be fixed to the terminal block 13 at two points as long as the nut fall-off prevention member 26 itself can stretch or the nut fall-off prevention member 26 is provided with a deforming portion such as a U-shaped structure, allowing the nut fall-off prevention member 26 to deform toward the main terminal 7.

[0085] <Effects> As described above, in the third embodiment and its modified example, the bus bar 10 is connected to the first main surface of the main terminal 7 by the bolt 11 and the nut 12, and the power module 202 is further provided with the nut fall-off prevention member 26 that is disposed between the main terminal 7 and the nut 12 and attached to the inside of the terminal block 13 closer to the heat sink 16 than the recess 17.

[0086] The manufacturing method of the power module 202 also includes the steps of: (a) arranging a busbar 10 on the first main surface of the main terminal 7, and then arranging a bolt 11 on the opposite side of the busbar 10 from the terminal block 13 to screw into a nut 12 previously placed in the recess 17; and (b) connecting the busbar 10 and the main terminal 7 by rotating the bolt 11 placed on the opposite side of the busbar 10 from the terminal block 13 to screw into the nut 12 placed in the recess 17.

[0087] Therefore, the nut anti-fall-off member 26 allows the terminal block 13 to be transported without the nut 12 falling off, eliminating the need to place the nut 12 on the terminal block 13 when assembling the power module 202, thereby improving productivity.

[0088] <Fourth Embodiment> In this embodiment, the power module 202 according to the above-described first to third embodiments is applied to a power conversion device. The application of the power module 202 according to the first to third embodiments is not limited to a specific power conversion device, but hereinafter, as the fourth embodiment, a case where the power module 202 according to the first to third embodiments is applied to a three-phase inverter will be described.

[0089] FIG. 39 is a block diagram showing the configuration of a power conversion system to which the power conversion device according to this embodiment is applied.

[0090] The power conversion system shown in Figure 39 is composed of a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power conversion device 200. The power supply 100 can be composed of various components, such as a DC system, a solar cell, or a storage battery, or it may be composed of a rectifier circuit connected to an AC system or an AC / DC converter. The power supply 100 may also be composed of a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0091] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, and converts DC power supplied from the power source 100 into AC power and supplies the AC power to the load 300. As shown in Figure 39, the power conversion device 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal to the main conversion circuit 201 to control the main conversion circuit 201.

[0092] The load 300 is a three-phase electric motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is an electric motor mounted on various electrical devices, and is used as an electric motor for, for example, a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device.

[0093] The power conversion device 200 will be described in detail below. The main conversion circuit 201 includes switching elements (not shown) and freewheeling diodes (not shown). The switching elements convert DC power supplied from the power source 100 into AC power, which is supplied to the load 300. While the main conversion circuit 201 can have a variety of specific circuit configurations, the main conversion circuit 201 according to this embodiment is a two-level, three-phase full-bridge circuit that can be configured with six switching elements and six freewheeling diodes connected in anti-parallel to each switching element. At least one of the switching elements and freewheeling diodes of the main conversion circuit 201 is configured with a power module 202 according to any one of the first to third embodiments. Two of the six switching elements are connected in series to form upper and lower arms, which constitute each phase (U phase, V phase, and W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0094] The main conversion circuit 201 also includes a drive circuit (not shown) that drives each switching element. The drive circuit may be built into the power module 202, or may be provided separately from the power module 202. The drive circuit generates drive signals that drive the switching elements of the main conversion circuit 201 and supplies them to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, in accordance with control signals from a control circuit 203 (described later), the drive circuit outputs to the control electrodes of each switching element a drive signal that turns the switching element on and a drive signal that turns the switching element off. When maintaining a switching element in the on state, the drive signal is a voltage signal (on signal) that is equal to or higher than the threshold voltage of the switching element, and when maintaining a switching element in the off state, the drive signal is a voltage signal (off signal) that is equal to or lower than the threshold voltage of the switching element.

[0095] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that the desired power is supplied to the load 300. Specifically, it calculates the time (on time) that each switching element of the main conversion circuit 201 should be in the on state based on the power to be supplied to the load 300. For example, the main conversion circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output. The control circuit 203 then outputs a control command (control signal) to a drive circuit included in the main conversion circuit 201 so that an on signal is output to a switching element that should be in the on state at each time point, and an off signal is output to a switching element that should be in the off state at each time point. In accordance with this control signal, the drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switching element.

[0096] In the power conversion device according to this embodiment, the power modules 202 according to the first to third embodiments are applied as the switching elements and free wheel diodes of the main conversion circuit 201, thereby achieving improved productivity.

[0097] In this embodiment, an example has been described in which the power module 202 according to the first to third embodiments is applied to a two-level three-phase inverter, but the application of the power module 202 according to the first to third embodiments is not limited to this and can be applied to various power conversion devices. In this embodiment, a two-level power conversion device is described, but a three-level or multi-level power conversion device may also be used, and when supplying power to a single-phase load, the power module 202 according to the first to third embodiments may be applied to a single-phase inverter. Furthermore, when supplying power to a DC load or the like, the power module 202 according to the first to third embodiments can also be applied to a DC / DC converter or an AC / DC converter.

[0098] Furthermore, the power conversion device to which the power module 202 according to the first to third embodiments is applied is not limited to the case where the load described above is an electric motor, but can also be used, for example, as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system, and can also be used as a power conditioner for a solar power generation system, a power storage system, etc.

[0099] Although this disclosure has been described in detail, the above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0100] It should be noted that the embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

[0101] Various aspects of the present disclosure are summarized below as appendices.

[0102] (Supplementary Note 1) A heat sink comprising: a semiconductor element; a frame having the semiconductor element mounted on one surface thereof; a module base having the frame disposed on one surface thereof; a main terminal that is a part of the frame; a molded portion that seals the semiconductor element, the frame, and the module base so that the main terminal is exposed; a base portion that is integrated with the other surface of the module base exposed from the molded portion; and a plurality of heat dissipation fins that protrude from the base portion on the opposite side to the module base; an external terminal connected by a bolt and a nut to a first main surface of the main terminal or a second main surface opposite to the first main surface; and a structural member fixed to the base portion of the heat sink and disposed between the main terminal or the external terminal and the base portion, wherein a recess is formed on the main terminal side of the structural member in which the nut or the head of the bolt can be disposed, and the bolt that screws into the nut disposed in the recess or the nut that screws into the bolt disposed in the recess is disposed on the opposite side of the structural member with respect to the external terminal, A power module, wherein an inner surface of the recess is provided with a rotation suppressing portion that suppresses rotation of the head of the nut or bolt placed in the recess.

[0103] (Supplementary Note 2) The power module according to Supplementary Note 1, wherein the recess has a first recess and a second recess formed closer to the heat sink than the first recess, the first recess and the second recess are connected to each other, and the first recess has a larger outline than the second recess when viewed from the main terminal side.

[0104] (Supplementary Note 3) The power module according to Supplementary Note 1 or Supplementary Note 2, wherein the main terminal extends in a first direction that is parallel to the base portion of the heat sink, and is exposed from the molded portion.

[0105] (Supplementary Note 4) The power module according to Supplementary Note 1 or Supplementary Note 2, wherein the main terminal has a first parallel portion exposed from the molded portion in a first direction that is parallel to the base portion of the heat sink, a first vertical portion extending from the first parallel portion in a second direction that is vertical, and a second parallel portion extending from the first vertical portion in the first direction, and the external terminal is connected to the second parallel portion of the main terminal.

[0106] (Appendix 5) A power module according to any one of Appendices 1 to 4, wherein the recess, the nut, and the head of the bolt are formed in a hexagonal shape when viewed from the main terminal side, the minimum width of the recess is smaller than the maximum width of the head of the nut and the bolt, and the rotation suppressing portion is configured based on the relationship between the minimum width of the recess and the maximum width of the head of the nut and the bolt.

[0107] (Supplementary Note 6) The power module according to any one of Supplementary Notes 1 to 5, wherein at least one protrusion is formed on an inner surface of the recess.

[0108] (Supplementary Note 7) The power module according to any one of Supplementary Note 1 to Supplementary Note 6, further comprising: a second structural member, the second structural member being attached to the heat sink side of the recess inside the structural member, the second structural member being connected to the first main surface of the main terminal by the bolt and the nut; and the second structural member being disposed between the main terminal and the nut and attached to the heat sink side of the recess inside the structural member.

[0109] (Supplementary Note 8) The power module according to Supplementary Note 7, wherein the second structural member is made of metal.

[0110] (Appendix 9) A power module described in any one of Appendices 1 to 8, wherein a mating portion is provided on the other surface of the module base, a mated portion that can be mated with the mating portion is provided on the surface of the base portion of the heat sink facing the module base, and the module base and the heat sink are integrated by mating the mating portion with the mated portion.

[0111] (Supplementary Note 10) A method for manufacturing the power module according to any one of Supplementary Note 1 to Supplementary Note 6, comprising: (a) a step of arranging the head of the nut or the bolt in the recess with the external terminal arranged on the first main surface or the second main surface of the main terminal, and arranging the bolt that screws into the nut arranged in the recess, or the nut that screws into the bolt arranged in the recess, on the opposite side of the structural member to the external terminal; and (b) a step of connecting the external terminal and the main terminal by rotating the bolt or the nut that is arranged on the opposite side of the structural member to the external terminal, and screwing it into the nut or the bolt arranged in the recess.

[0112] (Supplementary Note 11) A method for manufacturing the power module according to Supplementary Note 7 or Supplementary Note 8, comprising: (a) a step of arranging the bolt, which is to screw into the nut pre-placed in the recess, on the opposite side of the external terminal from the structural member, with the external terminal placed on the first main surface of the main terminal; and (b) a step of connecting the external terminal and the main terminal by rotating the bolt, which is placed on the opposite side of the structural member from the external terminal, to the nut placed in the recess.

[0113] (Supplementary Note 12) A power conversion device comprising: a main conversion circuit having the power module according to any one of Supplementary Note 1 to Supplementary Note 9, which converts input power and outputs the converted power; and a control circuit which outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

[0114] REFERENCE SIGNS LIST 1 semiconductor chip, 3 lead frame, 5 module base, 5a mating portion, 7 main terminal, 7a first parallel portion, 7b first vertical portion, 7c second parallel portion, 8 molded portion, 10 bus bar, 11 bolt, 12 nut, 13 terminal block, 14 base portion, 14a mating portion, 15 heat dissipation fin, 16 heat sink, 17 recess, 17a first recess, 17b second recess, 19 protrusion, 25, 26 nut fall-off prevention member, 200 power conversion device, 201 main conversion circuit, 202 power module, 203 control circuit.

Claims

1. A semiconductor element; a frame having the semiconductor element mounted on one surface thereof; a module base having the frame disposed on one surface thereof; A main terminal that is a part of the frame; a mold part that seals the semiconductor element, the frame, and the module base so that the main terminals are exposed; and a heat sink including a base portion integrated with the other surface of the module base exposed from the mold portion, and a plurality of heat dissipation fins protruding from the base portion on a side opposite to the module base; an external terminal connected by a bolt and a nut to a first main surface of the main terminal or a second main surface opposite to the first main surface; a structural member fixed to an outer periphery of a surface of the base portion of the heat sink facing the module base and disposed between the main terminal or the external terminal and the outer periphery of the surface of the base portion facing the module base, a recess in which a head of the nut or the bolt can be placed is formed on the main terminal side of the structural member, the bolt that screws into the nut disposed in the recess or the nut that screws into the bolt disposed in the recess is disposed on the opposite side of the structural member with respect to the external terminal, A power module, wherein an inner surface of the recess is provided with a rotation suppressing portion that suppresses rotation of the head of the nut or bolt placed in the recess.

2. A power module as described in claim 1, wherein the nut or bolt arranged in the recess is movable between the main terminal side and the heat sink side.

3. A power module as described in claim 1, having a space between a lower surface of the nut or bolt placed in the recess and an upper surface within the recess.

4. The recess includes a first recess and a second recess formed closer to the heat sink than the first recess, The first recess and the second recess are in communication with each other, The power module according to claim 1 , wherein the first recess has a larger contour than the second recess when viewed from the main terminal side.

5. 3 . The power module according to claim 1 , wherein the main terminal extends in a first direction that is parallel to the base portion of the heat sink, and is exposed from the molded portion. 4 .

6. the main terminal has a first parallel portion exposed from the molded portion in a first direction parallel to the base portion of the heat sink, a first vertical portion extending from the first parallel portion in a second direction vertical to the base portion of the heat sink, and a second parallel portion extending from the first vertical portion in the first direction; 3. The power module according to claim 1, wherein the external terminal is connected to the second parallel portion of the main terminal.

7. The recess, the nut, and the head of the bolt are formed in a hexagonal shape when viewed from the main terminal side, The minimum width of the recess is smaller than the maximum width of the head of the nut and the head of the bolt, 3. The power module according to claim 1, wherein the rotation suppressing portion is configured according to a relationship between a minimum width of the recess and a maximum width of the head portion of the nut and the bolt.

8. 3. The power module according to claim 1, wherein at least one protrusion is formed on an inner side surface of the recess.

9. the external terminal is connected to the first main surface of the main terminal by the bolt and the nut; 3. The power module according to claim 1, further comprising a second structural member disposed between the main terminal and the nut and attached to the heat sink side of the recess inside the structural member.

10. The power module according to claim 9 , wherein the second structural member is made of a metal.

11. a fitting portion is provided on the other surface of the module base, a mating portion that can be mated with the mating portion is provided on a surface of the base portion of the heat sink that faces the module base, 3. The power module according to claim 1, wherein the module base and the heat sink are integrated by fitting the fitting portion and the fitted portion together.

12. A method for manufacturing the power module according to claim 1 or 2, comprising the steps of: (a) placing the nut or the head of the bolt in the recess in a state in which the external terminal is placed on the first main surface or the second main surface of the main terminal, and placing the bolt that screws into the nut placed in the recess, or the nut that screws into the bolt placed in the recess, on the opposite side of the external terminal from the structural member; (b) rotating the bolt or the nut, which is arranged on the opposite side of the structural member from the external terminal, to screw it into the nut or the bolt, which is arranged in the recess, thereby connecting the external terminal and the main terminal.

13. A method for manufacturing the power module according to claim 9, comprising the steps of: (a) arranging the bolt, which is to be screwed into the nut, which is previously arranged in the recess, on an opposite side of the structural member to the external terminal, with the external terminal arranged on the first main surface of the main terminal; (b) rotating the bolt, which is arranged on the opposite side of the structural member from the external terminal, to screw the bolt into the nut, which is arranged in the recess, thereby connecting the external terminal and the main terminal.

14. A main conversion circuit having the power module according to claim 1 or 2, which converts input power and outputs the converted power; a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit; A power conversion device comprising: