Semiconductor module

Abstract

In a semiconductor module, heat dissipation performance is ensured, and damage to a wiring board caused by deformation during fastening of a heat dissipation base is prevented. The plurality of wiring boards on which the semiconductor elements are mounted and the heat dissipation base are bonded by a first bonding material. The heat dissipation base is warped so that a second surface, which is located on the opposite side from the first surface to which the plurality of wiring boards are joined, becomes a convex curved surface. Fastening holes are provided in at least a plurality of corners of the heat dissipation base. A bonding surface of each of the plurality of wiring boards facing the heat dissipation base includes: a first corner portion bonded to the heat dissipation base by a first bonding material; and a second corner part which is not bonded to the heat dissipation base by the first bonding material. The first bonding material bonds the plurality of wiring boards and the heat dissipation base such that the second corner portions of the wiring boards are located at four corners of a wiring board region including the entirety of the plurality of wiring boards.

Description

Technical Field

[0001] The present invention relates to a semiconductor module including a plurality of wiring boards on which semiconductor elements are mounted and a heat dissipation base to which the plurality of wiring boards are bonded. Background Art

[0002] As a semiconductor module used in a power conversion device such as an inverter device, there is a semiconductor module in which a heat sink base joined to a wiring board is mounted on a cooler (for example, refer to Patent Documents 1 to 7). Among the heat sink bases used in such semiconductor modules, there is a heat sink base formed in such a way that the second surface opposite to the first surface joined to the wiring board and facing the cooler is a convex curved surface.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-141023

[0006] Patent Document 2: Japanese Patent Application Publication No. 2015-72958

[0007] Patent Document 3: Japanese Patent Application Publication No. 2015-72957

[0008] Patent Document 4: Japanese Patent Application Publication No. 2004-134746

[0009] Patent Document 5: Japanese Patent Application Publication No. 2021-90030

[0010] Patent Document 6: Japanese Patent Application Publication No. 2017-79217

[0011] Patent Document 7: Japanese Patent Application Publication No. 2017-120888 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] The wiring board is bonded to the first surface of the heat dissipation base by bonding material. When the heat dissipation base having a convex curved surface on the second surface is mounted on the cooler, the second surface is deformed in the direction of changing from the convex curved surface to the flat surface. With the deformation of the heat dissipation base, stress is concentrated on the wiring board, and the wiring board may be damaged. In order to relieve the stress of the wiring board, it is also considered to reduce the bonding area of ​​the bonding material, but in this case, the heat dissipation is deteriorated.

[0014] In one aspect, an object of the present invention is to provide a semiconductor module capable of preventing damage to a wiring board caused by deformation during fastening of a heat dissipation base while ensuring heat dissipation performance.

[0015] Solutions for solving problems

[0016] 19. The semiconductor module of a technical solution comprises: a plurality of wiring boards on which semiconductor elements are mounted; a heat sink having a first surface to which the plurality of wiring boards are bonded and a second surface located on the opposite side to the first surface; and a first bonding material that bonds the plurality of wiring boards to the heat sink, the heat sink being warped in such a manner that the second surface becomes a convex curved surface, fastening holes being provided at at least a plurality of corners of the heat sink, the bonding surfaces of each of the plurality of wiring boards that are opposite to the heat sink comprising: a first corner portion that is bonded to the heat sink using the first bonding material; and a second corner portion that is not bonded to the heat sink using the first bonding material, the first bonding material bonding the plurality of wiring boards to the heat sink in such a manner that the second corner portions of the wiring boards are located at four corners of a wiring board region that includes the entirety of the plurality of wiring boards.

[0017] Effects of the Invention

[0018] According to the above-described configuration, it is possible to prevent damage to the wiring board caused by deformation during fastening of the heat dissipation base while ensuring heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a plan view showing the semiconductor module according to the first embodiment.

[0020] Figure 2 yes Figure 1 II-II sectional view.

[0021] Figure 3 This is an explanatory diagram for explaining the warping shape of the second surface (lower surface) of the heat dissipation base in the first embodiment.

[0022] Figure 4 This is an explanatory diagram for explaining a partial convex portion of the second surface of the heat dissipation base in the first embodiment.

[0023] Figure 5 This is an example circuit diagram of a semiconductor module according to the first embodiment (part 1).

[0024] Figure 6 This is an example circuit diagram of the semiconductor module according to the first embodiment (part 2).

[0025] Fig. 7A is a semiconductor module in a comparative example. Figure 1 The sectional view (one of them) corresponds to the II-II sectional view.

[0026] Figure 7B is a semiconductor module in a comparative example, and Figure 1The sectional view (part 2) corresponding to the II-II sectional view.

[0027] Figure 7C is a semiconductor module in a comparative example, and Figure 1 The sectional view (part 3) corresponding to the sectional view II-II.

[0028] Figure 8 It is a plan view showing a semiconductor module according to a modification of the first embodiment.

[0029] Fig. 9 It is a plan view transparently showing a first bonding material of a wiring board in a modified example of the first embodiment.

[0030] Fig. 10A A semiconductor module according to a second embodiment of the present invention is shown. Figure 1 The sectional view (one of them) corresponds to the II-II sectional view.

[0031] Fig. 10B A semiconductor module according to a second embodiment of the present invention is shown. Figure 1 The sectional view (part 2) corresponding to the II-II sectional view.

[0032] Fig.11A A semiconductor module according to a third embodiment of the present invention is shown. Figure 1 The sectional view (one of them) corresponds to the II-II sectional view.

[0033] Fig. 11B A semiconductor module according to a third embodiment of the present invention is shown. Figure 1 The sectional view (part 2) corresponding to the II-II sectional view.

[0034] Fig. 12A A semiconductor module according to a fourth embodiment of the present invention is shown. Figure 1 The sectional view (one of them) corresponds to the II-II sectional view.

[0035] Fig. 12B A semiconductor module according to a fourth embodiment of the present invention is shown. Figure 1 The sectional view (part 2) corresponding to the II-II sectional view.

[0036] Description of Reference Numerals

[0037] 1, 1A, 2, 2, 3, 4, semiconductor module; 10, wiring board; 11, first conductor layer; 12, second conductor layer; 13, insulating layer; 13a, stress concentration portion; 14, 15, semiconductor element; 16, joint surface; 16a, first corner; 16b, second corner; 20, heat sink; 21, first surface; 22, second surface; 23, fastening hole; 50, wiring board; 52, second conductor layer; 52a, solder resist; 60, heat sink; 61, first surface; 61a, solder resist; 70, wiring board; 72 , the second conductor layer; 72a, solder resist; 80, heat sink; 81, the first surface; 81a, solder resist; 100, energy conversion device; 110, cooler; 120, screw; A, wiring board area; A1, four corners; D, diagonal line; C, thermal conductive material; P1, P2, reference position; P3, central position; P4, local protrusion; S, bonding material; S1 (S1A, S11, S21, S31, S41), the first bonding material; S2, the second bonding material; W1, main current wiring; W2, control wiring. DETAILED DESCRIPTION

[0038] Hereinafter, the semiconductor modules of the first to fourth embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the X, Y, and Z axes in the referenced figures are shown for the purpose of defining the directions and faces in the illustrated semiconductor modules, etc. The X, Y, and Z axes are orthogonal to each other and form a right-hand system. In the following description, the Z direction is sometimes referred to as the up-down direction. In addition, the surface including the X axis and the Y axis is sometimes referred to as the upper surface or the lower surface. These directions and surfaces are terms used for the convenience of description, and the corresponding relationship with the XYZ directions may sometimes change depending on the installation posture of the semiconductor module, etc. For example, in this specification, the surface facing the positive side (+Z direction) of the member constituting the semiconductor module is referred to as the upper surface, and the surface facing the negative side (-Z direction) of the Z direction is referred to as the lower surface, but the surface facing the negative side of the Z direction may also be referred to as the upper surface, and the surface facing the positive side of the Z direction may be referred to as the lower surface. In addition, in this specification, the top view refers to the situation where the upper surface (XY surface) of the semiconductor module, etc. is observed from the positive side of the Z direction to the negative side of the Z direction.

[0039] The aspect ratios and the size relationships of the components in the drawings are only schematic representations and may not be consistent with the relationships in the semiconductor modules actually manufactured. For the sake of convenience, the size relationships of the components are sometimes exaggerated. In addition, the shapes of the same components may also be different between different drawings.

[0040] In the following description, as examples of the semiconductor module of the embodiment and the energy conversion device having the semiconductor module, a device applied to an inverter device of an industrial or vehicle-mounted motor or other power conversion device is listed. Therefore, in the following description, detailed descriptions of the structure, function, operation, assembly method, etc. that are the same as or similar to the known semiconductor module and energy conversion device are omitted.

[0041] <First Embodiment>

[0042] Figure 1 It is a plan view showing the semiconductor module 1 . Figure 2 yes Figure 1 II-II sectional view. Figure 3 This is an explanatory diagram for explaining the warping shape of the second surface (lower surface) 22 of the heat dissipation base 20 . Figure 4 This is an explanatory diagram for explaining the local protrusion P4 of the second surface 22 . Figure 5 and Figure 6 is a circuit diagram example of the semiconductor module 1. Figure 1 and Figure 3 In FIG. 1 , the first bonding material S1 is indicated by a dotted line (hidden line), and the wiring board region A is indicated by a two-dot chain line (imaginary line).

[0043] Figure 1 and Figure 2 The semiconductor module 1 shown includes a plurality of wiring boards 10 , a heat dissipation base 20 , and a first bonding material S1 . Figure 2 The energy conversion device 100 shown includes a semiconductor module 1 , a cooler 110 , and a plurality of screws 120 .

[0044] like Figure 2 As shown, the semiconductor module 1 is mounted on the cooler 110 using a screw member 120 that penetrates the fastening hole 23 of the heat dissipation base 20. The screw member 120 has an external thread that is threadedly engaged with the threaded hole (internal thread) of the cooler 110. The cooler 110 is, for example, a water-cooling jacket integrated type with a heat sink, a water-cooling jacket, etc., or an open heat sink type in which the heat sink is exposed to the outside. The heat dissipation base 20 of the semiconductor module 1 is connected to the cooler 110 via a heat conductive material C such as thermal grease or a heat conductive compound.

[0045] A plurality of (e.g., four) wiring boards 10 are bonded to a first surface 21 (upper surface) of a common single heat dissipation base 20 at a bonding surface 16 as a lower surface. The wiring board 10 includes a first conductor layer 11, a second conductor layer 12, and an insulating layer 13. The wiring board 10 can be, for example, a DCB (Direct Copper Bonding) substrate or an AMB (Active Metal Brazing) substrate. The wiring board 10 can also be called a laminated substrate, an insulating circuit substrate, an insulating heat dissipation circuit substrate, etc.

[0046] The insulating layer 13 is, for example, a ceramic substrate. The insulating layer 13 is not limited to a specific substrate, and may be, for example, a ceramic substrate formed of a ceramic material such as aluminum nitride (AlN), aluminum oxide (Al2O3), silicon nitride (Si3N4), and a composite material of aluminum oxide (Al2O3) and zirconium oxide (ZrO2). The insulating layer 13 may also be, for example, a substrate formed by molding an insulating resin such as epoxy resin, a substrate formed by impregnating an insulating resin into a base material such as glass fiber, a substrate formed by coating the surface of a flat metal core with an insulating resin, etc.

[0047] The second conductor layer 12 is a member that functions as a heat conducting member that conducts heat generated by the inverter circuit to the heat dissipation base 20, and is formed of, for example, a metal plate or metal foil such as copper or aluminum. The second conductor layer 12 (wiring board 10) is bonded to the heat dissipation base 20 using a first bonding material S1 such as solder. The second conductor layer 12 may also be referred to as a heat dissipation layer, a heat dissipation plate, a heat dissipation pattern, a conductor pattern, etc.

[0048] The first conductor layer 11 functions as a wiring member in the inverter circuit and is formed of a metal plate or metal foil such as copper or aluminum. The first conductor layer 11 may also be called a conductor plate, a conductor pattern, a conductive layer, a wiring pattern, or the like.

[0049] As an example, Figure 1 As shown, the first conductor layer 11 is bonded with a bonding material S such as solder (see Figure 2 ) Four semiconductor elements 14 and four semiconductor elements 15 are mounted in a manner that four are arranged in the X direction.

[0050] The semiconductor element 14 is, for example, an IGBT (Insulated Gate Bipolar Transistor) as a switching element, and the semiconductor element 15 is, for example, a FWD (Free Wheeling Diode) element as a diode element. As the semiconductor element 14 and the semiconductor element 15, other semiconductor elements such as an RC (Reverse Conducting)-IGBT element in which a switching element and a diode element connected in reverse parallel to the switching element are integrated can also be configured. The switching element and the diode element in the semiconductor elements 14 and 15 are not limited to Si substrates, and can be formed, for example, as a semiconductor substrate using wide bandgap semiconductors such as SiC (silicon carbide) and GaN (gallium nitride). In addition, the switching element of the semiconductor element 14 can also be composed of, for example, SiC-MOSFET (Metal Oxide Semiconductor Field Effect Transistor), BJT (Bipolar Junction Transistor), etc. The diode element of the semiconductor element 15 may be formed of, for example, a SiC-SBD (Schottky Barrier Diode), a JBS (Junction Barrier Schottky) diode, an MPS (Merged PN Schottky) diode, a PN diode, or the like.

[0051] The four wiring boards 10 can be identical wiring boards 10 or symmetrically shaped wiring boards 10. For example, Figure 1 The wiring board 10 on the upper left (positive side in the Y direction and negative side in the X direction) is preferably the same shape as the wiring board 10 on the upper right (positive side in the Y direction and positive side in the X direction) or has a symmetrical shape. Figure 1 The wiring board 10 on the upper left in the figure can be set to Figure 1 The wiring board 10 at the lower left (negative side in the Y direction and negative side in the X direction) in FIG. Figure 1 The wiring board 10 in the lower right (negative side in the Y direction and positive side in the X direction) in FIG. 1 is the same as or a wiring board with a bilaterally symmetrical shape rotated 180 degrees in a plan view.

[0052] The main electrode provided on the upper surface of the semiconductor element 14, 15 is connected to other semiconductor elements 14, 15, the first conductor layer 11 or an input terminal not shown in the figure by the main current wiring W1. For example, the semiconductor module 1 has two first input terminals (E terminals), two second input terminals (C terminals), and auxiliary input terminals (C terminals, E terminals). These terminals can be Figure 5 As shown in the circuit diagram, the terminals (C, E) function as a set of common circuits, and can also be as shown in Figure 6 The input terminals and control terminals are preferably fixed integrally to a housing (not shown) that covers the periphery of the four wiring boards 10, for example. In addition, as shown in the circuit diagram of FIG. 1 , the control electrodes (e.g., gate electrodes) provided on the upper surfaces of the semiconductor elements 14 and 15 are indirectly or directly connected to the control terminals (G) not shown in the figure by means of the control wiring W2 via the first conductor layer 11. Figure 1 As shown in FIG. 1 , at four corners A1 of a wiring board region A (i.e., the smallest rectangular region surrounding all wiring boards 10 in a plan view) including the entirety of four wiring boards 10 formed of four wiring boards 10, the first conductor layer 11 (connected to the control terminal) is connected only to the control wiring W2 of the main current wiring W1 and the control wiring W2. Therefore, the main current does not flow in the first conductor layer 11 at the four corners A1.

[0053] like Figure 1 As shown, the shape of the heat dissipation base 20 when viewed from above is rectangular, and fastening holes 23 for inserting screws 120 are provided at 4 locations at the four corners and 2 locations at the center of the X direction at both ends in the Y direction, a total of 6 locations. The corners of the heat dissipation base 20 when viewed from above are preferably rounded. In addition, the corners of the wiring board 10 when viewed from above are preferably chamfered.

[0054] The heat dissipation base 20 is a member that functions as a heat conduction member that conducts the heat generated by the semiconductor elements 14 and 15 to the cooler 110, and is formed of a metal plate such as a copper plate or an aluminum plate. The heat dissipation base 20 is formed by, for example, using a press process to warp the second surface 22 of the flat metal plate so that it becomes a convex curved surface. Figure 2 The distance between the heat dissipation base 20 and the cooler 110 in the vertical direction is shown, in particular, before the heat dissipation base 20 is mounted on the cooler 110 by the screw 120, the distance G2 of the peripheral portion when viewed from above is greater than the distance G1 of the central portion when viewed from above. In addition, the above-mentioned thermal conductive material C is interposed between the heat dissipation base 20 and the cooler 110.

[0055] The shape, number of configurations, and configuration locations of the wiring board 10 of the semiconductor elements 14, 15, etc. in the semiconductor module 1 can be appropriately changed. For example, the number of wiring boards 10 is not limited to four, and can be set to any number of two or more. In addition, a plurality of wiring boards 10 can also be arranged in only one direction (X direction or Y direction). In addition, the layout of the first conductor layer 11 as a wiring member provided on the upper surface side of the wiring board 10 is changed according to the type, shape, number of configurations, and configuration location of the semiconductor elements 14, 15 mounted thereon. In addition, the main current wiring W1 and the control wiring W2 in the above-mentioned semiconductor module 1 are, for example, metallic bonding wires, but part or all of them can also be replaced by leads formed by processing a metal plate such as a copper plate, for example.

[0056] Here, refer to Figure 7A to Figure 7C , a semiconductor module according to a comparative example in which wiring board 10 is damaged when heat dissipation base 20 is mounted on cooler 110 is described. Figure 7A to Figure 7C For Figure 1 The II-II sectional view corresponds to the sectional view at the position.

[0057] In order to improve the closeness between the heat dissipation base 20 and the cooler 110 by using a heat conductive material C such as thermal grease, for example, Fig. 7A As shown, a plurality of thermally conductive materials C are arranged in a dotted pattern on the second surface 22 of the heat dissipation base 20 before being attached to the cooler 110. Before the heat dissipation base 20 is attached to the cooler 110, the four wiring boards 10 are sealed with a sealing resin (gel) not shown.

[0058] The second surface 22 of the heat dissipation base 20 extends in a convex curved surface, that is, in a vertical direction, the position is higher at the periphery and lower at the center. Therefore, when the heat dissipation base 20 is arranged on the cooler 110, the heat conductive material C arranged at the center of the second surface 22 of the heat dissipation base 20 first contacts the upper surface of the cooler 110. Then, when the heat dissipation base 20 is pressed against the cooler 110 when the screw 120 is tightened, Figure 7B As shown, the thermal conductive material C is radially extended from the center of the second surface 22 of the heat dissipation base 20 and integrated with the upper surface of the cooler 110. At this time, by pre-setting the second surface 22 of the heat dissipation base 20 as a convex curved surface, the thermal conductive material C is easy to radially extend from the center of the second surface 22 of the heat dissipation base 20, and it is not easy to generate gaps in the integrated thermal conductive material C.

[0059] When the heat dissipation base 20 is mounted on the cooler 110, a plurality of wiring boards 10 are joined to the heat dissipation base 20. When the heat dissipation base 20 is mounted on the cooler 110, after the heat conductive material C is extended between the heat dissipation base 20 and the cooler 110 as described above, the heat dissipation base 20 is fixed to the cooler 110 using the screws 120.

[0060] Therefore, the heat sink 20 is deformed in such a way that the convex curved surface of the second surface 22 becomes a nearly flat curved surface. That is, when the heat sink 20 is mounted on the cooler 110 using the screw 120, the heat sink 20 is deformed in a direction in which the warping becomes smaller than before the mounting. If the heat sink 20 is deformed in a direction in which the warping becomes smaller, deformation stress is applied to the wiring board 10 bonded to the first surface 21 of the heat sink 20. For example, stress is concentrated in the slit between the first conductor layers 11 near the screw 120 (or the periphery of the first conductor layer 11) ( Figure 7C The stress concentration portion 13a shown in the figure causes damage to the wiring board 10 such as cracking of the insulating layer 13.

[0061] In the comparative example described above, the bonding surface 16 of the wiring board 10 to the heat sink 20 has only the first corner 16a bonded to the heat sink 20 by the first bonding material S11. That is, all four corners of the bonding surface 16 are the first corners 16a bonded to the heat sink 20.

[0062] In contrast, in the first embodiment, Figure 1 As shown by the dotted line, the first bonding material S1 does not reach the four corners A1 of the wiring board area A, and the bonding surface 16 of the wiring board 10 has only the second corners 16b at the four corners A1 of the wiring board area A that are not bonded to the heat sink 20 by the first bonding material S1. Figure 2 The second corner 16b shown is not only lacking in the first bonding material S1, but also lacking in the second conductor layer 12. The above-mentioned sealing resin of the sealed wiring board 10 enters the lacking portion. The lacking portion of the second conductor layer 12 can be formed, for example, by etching. It is preferred that the remaining three corners of the bonding surface 16 of the wiring board 10 are the first corners 16a bonded to the heat dissipation base 20 using the first bonding material S1. In addition, at the corners of the bonding surface 16, if the area not bonded to the heat dissipation base 20 has a relative size, the wider corner of the unbonded area can also be regarded as the second corner 16b, and the narrower corner of the unbonded area can be regarded as the first corner 16a. In addition, the second corners 16b may not be provided at all four corners A1 of the wiring board area A, as long as one or more second corners 16b of the wiring board 10 are arranged at the four corners A1.

[0063] Here, the local convex portion (local convex shape position) P4 of the second surface 22 of the heat dissipation base 20 is described. Figure 3 As shown, in the lower surface of the heat dissipation base 20, that is, the second surface 22, the positions where the diagonal line D connecting the fastening hole 23 (the center of the fastening hole 23) and the two ends of the area corresponding to the wiring board area A (the area at the same position as the wiring board area A when viewed from above) intersect are set as reference positions P1 and P2. In addition, the middle position of the two reference positions P1 and P2 on the second surface 22 is set as the central position P3. In addition, since the second surface 22 of the heat dissipation base 20 extends in a manner that becomes a convex curved surface, the diagonal line D can be said to be a line along the curved surface. In addition, the reference positions P1 and P2 can also be referred to as positions where the distance L from the center of the fastening hole 23 is a specified distance.

[0064] Figure 4 The black solid line in FIG. 1 shows the warping shape of the second surface 22 (lower surface) of the heat dissipation base 20 along the diagonal line D. With the position in the up-down direction (convex-concave) of the reference position P1 (P2) as the origin, Figure 4 The upper part of the figure has a larger protrusion (convex), while the lower part has a smaller protrusion (concave).

[0065] Then, draw an auxiliary line (gray dotted line) connecting the position of the warped shape at the center position P3 with the reference positions P1 and P2. In addition, the difference between the warped shape and the auxiliary line is set as an auxiliary height curve (gray solid line). The position on the diagonal line D where the protrusion of the auxiliary height curve is the largest (peak position) is set as the local protrusion P4. In addition, the local protrusion P4 can also be obtained by using another diagonal line intersecting with the diagonal line D, and both can be set as the local protrusion P4, or only the one with a larger protrusion can be set as the local protrusion P4. Figure 1 In the figure, the local convex portion P4 is shown in Figure 1 The first bonding material S1 is preferably located at a position closer to the central position P3 than the local protrusion P4. That is, the first bonding material S1 is preferably located at a position spaced apart from the local protrusion P4 of the heat dissipation base 20 toward the central position P3. The closer the local protrusion P4 is to the slit between the first conductor layers 11 near the screw 120 where stress is easily concentrated (or the periphery of the first conductor layer 11), the stronger the stress applied to the slit.

[0066] In the first embodiment described above, the semiconductor module 1 includes a plurality of wiring boards 10 on which semiconductor elements 14 and 15 are mounted, a heat sink 20, and a first bonding material S1. The heat sink 20 has a first surface 21 to which the plurality of wiring boards 10 are bonded, and a second surface 22 located on the opposite side of the first surface 21. The first bonding material S1 bonds the plurality of wiring boards 10 to the heat sink 20. The heat sink 20 is warped in such a manner that the second surface 22 becomes a convex curved surface. Fastening holes 23 are provided at at least a plurality of corners of the heat sink 20. The bonding surface 16 of each of the plurality of wiring boards 10, which faces the heat sink 20, includes a first corner 16a bonded to the heat sink 20 by the first bonding material S1 and a second corner 16b not bonded to the heat sink 20 by the first bonding material S1. The first bonding material S1 bonds the plurality of wiring boards 10 to the heat dissipation base 20 such that the second corner portions 16 b of the wiring boards 10 are located at the four corners A1 of the wiring board region A including the entirety of the plurality of wiring boards 10 .

[0067] Thus, when the heat sink 20 is mounted on the cooler 110 or the like, even if the second surface 22 of the heat sink 20 is deformed in the direction of changing from a convex curved surface to a flat surface, since the wiring board 10 is not joined to the heat sink 20 at the second corners 16b of the four corners A1 of the wiring board area A, the wiring board 10 does not follow the deformation of the heat sink 20 in the vicinity of the fastening holes 23, and stress concentration on the wiring board 10 can be suppressed. In addition, compared with a configuration in which the wiring board 10 has the second corners 16b at all corners other than the four corners A1 of the wiring board area A, heat dissipation from the wiring board 10 to the heat sink 20 can be ensured at the first corners 16a. Therefore, according to the first embodiment, while ensuring heat dissipation, damage to the wiring board 10 caused by deformation during fastening of the heat sink 20 can be prevented. In addition, when all the corners of the joint surface 16 of the wiring board 10 are set as the first corners 16a, when the heat dissipation base 20 is installed (fastened) to the cooler 110, there is a 5% chance that horizontal cracks will be generated in the insulating layer 13 of the wiring board 10 along the direction intersecting the diagonal line D, and the wiring board 10 will fail (be damaged). However, by providing the second corners 16b only at the four corners A1 of the wiring board area A as in the first embodiment, the failure rate of the semiconductor module 1 is reduced to 0%.

[0068] In the first embodiment, the wiring board 10 includes the insulating layer 13, the first conductor layer 11 provided on the surface of the insulating layer 13 on the semiconductor elements 14 and 15 side, and the second conductor layer 12 provided on the surface of the insulating layer 13 on the heat sink 20 side. The second conductor layer 12 is missing at the second corner 16b.

[0069] Thus, even if the first bonding material S1 overflows to the second corner portion 16b, it will not bond to the insulating layer 13, and it is possible to more reliably prevent damage to the wiring board 10. In addition, the amount of material used in the second conductor layer 12 can be reduced.

[0070] In the first embodiment, the semiconductor module 1 includes the main current wiring W1 and the control wiring W2 , and the first conductor layer 11 is connected only to the control wiring W2 at the four corners A1 of the wiring board area A, and the main current does not flow.

[0071] Thus, the wiring board 10 does not reach a high temperature at the second corners 16 b (four corners A1 of the wiring board region A) of the bonding surface 16 where the wiring board 10 and the heat dissipation base 20 are not bonded, and it is possible to avoid loss of heat dissipation.

[0072] Furthermore, in the first embodiment, when the positions where the diagonal line D connecting the fastening holes 23 intersects with the two ends of the area corresponding to the wiring board area A are set as the reference positions P1 and P2, and the middle position between the two reference positions P1 and P2 is set as the central position P3, the heat dissipation base 20 has a local protrusion P4 on the second surface (lower surface) 22, which is a position where the protrusion amount of the convex curved surface relative to the auxiliary line connecting the two reference positions P1 and P2 and the central position P3 is the largest. The first bonding material S1 is located at a position spaced apart from the local protrusion P4 of the heat dissipation base 20 toward the central position P3.

[0073] Thus, in the local protrusions ( P4 ) where stress is likely to concentrate in the wiring board 10 , the wiring board 10 does not follow the deformation of the heat dissipation base 20 , so that the stress concentration on the wiring board 10 can be more reliably suppressed.

[0074] <Modification of the First Embodiment>

[0075] Figure 8 It is a plan view showing a semiconductor module 1A according to a modification of the first embodiment. Fig. 9 It is a plan view transparently showing the first bonding material S1A of the wiring board 10 .

[0076] In the semiconductor module 1A of this modified example, the second corners 16b where the wiring board 10 and the heat dissipation base 20 are not bonded by the first bonding material S1A are provided not only at the four corners A1 of the wiring board region A but also near the two fastening holes 23 at the center in the X direction. Other matters can be the same as the above description, so the description is omitted.

[0077] like Figure 8 and Fig. 9As shown, the bonding surface 16 of the wiring board 10 has second corners 16b (see FIG. 1 ) where the wiring board 10 and the heat sink 20 are not bonded at the four corners A1 of the wiring board region A. Fig. 9 ). In addition, the bonding surface 16 also has a second corner portion 16b at one corner portion adjacent to (adjacent to across one side) the second corner portion 16b of the four corners A1 of the wiring board area A. On the other hand, the bonding surface 16 has a first corner portion 16a at which the wiring board 10 and the heat dissipation base 20 are bonded at the remaining two adjacent corner portions.

[0078] The second corner 16b at a position different from the four corners A1 of the wiring board area A is preferably provided at a corner near the two fastening holes 23 at the center in the X direction. In addition, in the second corner 16b of this modification, it is also preferred that not only the first bonding material S1A but also the second conductor layer 12 is lacking. In addition, the first bonding material S1A is located at a position farther from the local protrusion P4 toward the central position P3 (refer to Figure 3 ) side with a distance therebetween.

[0079] The first bonding material S1A has a symmetrical shape at the two second corners 16b (at Figure 8 It is better that the four wiring boards 10 are all symmetrical. Fig. 9 In the example of FIG. 1 , the first bonding material S1A is provided with a symmetrically shaped defect with respect to a center line (one-dot chain line) extending in the Y direction at the center in the X direction.

[0080] In the modification of the first embodiment described above, the same effects as those of the first embodiment can be obtained, namely, damage to the wiring board 10 caused by deformation of the heat dissipation base 20 during fastening can be prevented while ensuring heat dissipation.

[0081] In the present variation, bonding surface 16 of each of the plurality of wiring boards 10 includes two adjacent first corners 16a and two adjacent second corners 16b, and first bonding material S1A is symmetrically absent at the two second corners 16b.

[0082] Thus, for example, when four (or more) wiring boards 10 are of the same shape, when each wiring board 10 is of a symmetrical shape, etc., not only can the wiring boards 10 be made of the same shape or a symmetrical shape, but also the first bonding material S1A can be made of the same shape or a symmetrical shape. In addition, compared with a configuration in which the first bonding material S1A is lacking in an asymmetrical shape at the two second corners 16b, the configuration of the first bonding material S1A becomes easier.

[0083] <Second Embodiment>

[0084] Fig. 10A and Fig. 10BThe semiconductor module 2 according to the second embodiment is shown in FIG. Figure 1 The II-II sectional view corresponds to the sectional view at the position.

[0085] In the semiconductor module 2 of the second embodiment, the second conductor layer 52 of the wiring board 50 has a solder resist 52a provided at the second corner portion 16b. Other matters can be the same as those of the first embodiment described above, so the reference numerals other than the wiring board 50, the second conductor layer 52, the solder resist 52a and the first bonding material S21 are shown in the figure. Fig. 10A and Fig. 10B The same reference numerals as those in the above-mentioned first embodiment are given and the description thereof will be omitted.

[0086] like Fig. 10A As shown, the second conductor layer 52 has a solder resist 52a at the second corner 16b where the wiring board 50 and the heat dissipation base 20 are not bonded by the first bonding material S21. The solder resist 52a is an example of a non-bonding processed portion applied to the second conductor layer 52. The non-bonding processed portion may be any processed portion that allows the second conductor layer 52 (wiring board 50) and the heat dissipation base 20 to be bonded without using the first bonding material S21, and is not limited to the solder resist 52a.

[0087] The solder resist 52a has a property that it does not adhere to the first bonding material S21 even if it contacts the first bonding material S21, and therefore does not bond to the heat dissipation base 20. Fig. 10B As shown, when the heat dissipation base 20 is mounted on the cooler 110 using the screw 120, even if the second surface 22 of the heat dissipation base 20 is deformed in the direction of changing from a convex curved surface to a flat surface, the wiring board 50 does not follow the deformation of the heat dissipation base 20 at the second corner 16b near the fastening hole 23. Therefore, a gap in the vertical direction is generated between the solder resist 52a and the first bonding material S21.

[0088] In addition, in the second embodiment, similar to the modified example of the first embodiment, the bonding surface 16 of each wiring board 50 of the plurality of wiring boards 50 may include two first corner portions 16a adjacent to each other and two second corner portions 16b adjacent to each other, and the first bonding material S21 may be missing in a symmetrical shape at the two second corner portions 16b.

[0089] In the second embodiment described above, the same effects as those of the first embodiment can be obtained with regard to the same matters as those of the first embodiment, namely, the effects of preventing damage to the wiring board 50 caused by deformation of the heat dissipation base 20 during fastening while ensuring heat dissipation properties.

[0090] In the second embodiment, the second conductor layer 52 of the wiring board 50 has a solder resist 52a (an example of a non-joining processed portion) applied to the second corner portion 16b not joined to the heat dissipation base 20 by the first joining material S21.

[0091] Thus, at the location of the wiring board 50 Figure 1 In the second corner 16b of the four corners A1 of the wiring board area A shown, the solder resist 52a (wiring board 50) is not bonded to the heat sink 20, so the wiring board 50 does not follow the deformation of the heat sink 20 near the fastening hole 23. Therefore, at the second corner 16b, the second conductor layer 52 does not need to be missing, but by a simple process using the solder resist 52a, even if the first bonding material S21 is located at the second corner 16b, the wiring board 50 and the heat sink 20 will not be bonded, and damage to the wiring board 50 can be more reliably prevented.

[0092] In addition, the solder resist 52a may be arranged on the entire surface of the portion without the second conductor layer 52 on the back side of the wiring board 50 in a manner that surrounds the second conductor layer 52. In this case, the portion joined to the first bonding material S21 can be reliably controlled. In particular, when the solder resist 52a is arranged only at the boundary between the second corner 16b and the region joined to the first bonding material S21, the first bonding material S21 may also go over the solder resist 52a and be arranged at the second corner 16b, causing the second corner 16b to be joined to the heat dissipation base 20. It is desirable to cover the entire vicinity of the second corner 16b with the solder resist 52a to prevent the first bonding material S21 from going over the solder resist 52a and coming to the vicinity of the second corner 16b.

[0093] <Third Embodiment>

[0094] Fig.11A and Fig. 11B The semiconductor module 3 according to the third embodiment is shown. Figure 1 The II-II sectional view corresponds to the sectional view at the position.

[0095] In the semiconductor module 3 of the third embodiment, the heat dissipation base 60 has a solder resist 61a in the region of the first surface 61 that faces the second corner portion 16b. Other matters are the same as those of the first embodiment described above, so reference numerals other than the heat dissipation base 60, the first surface 61, the solder resist 61a, and the first bonding material S31 are shown in the figure. Fig.11A and Fig. 11B The same reference numerals as those in the above-mentioned first embodiment are given and the description thereof will be omitted.

[0096] like Fig.11AAs shown, the first surface 61 has a solder resist 61a in an area opposite to the second corner 16b where the wiring board 10 and the heat sink 60 are not bonded by the first bonding material S31. The solder resist 61a is an example of a non-bonding processed portion applied to the first surface 61 of the heat sink 60. The non-bonding processed portion may be any processed portion that does not bond the heat sink 60 and the heat sink 20 by the first bonding material S31, and is not limited to the solder resist 61a. For example, since it is difficult for the first bonding material S31 to enter the portion of the first surface 61 of the heat sink 60 that is smeared with a pencil, if the smearing process is performed with a pencil to prevent the first bonding material S31 from entering the second corner 16b, the processed portion functions as a non-bonding processed portion.

[0097] Even if the solder resist 61a contacts the first bonding material S31, it will not bond to the wiring board 10. Fig. 11B As shown, when the heat sink base 20 is installed on the cooler 110 using the screw 120, even if the second surface 22 of the heat sink base 60 is deformed in the direction changing from a convex curved surface to a flat surface, at the second corner 16b near the fastening hole 23, the wiring board 10 will not follow the deformation of the heat sink base 60, and a gap in the up and down directions will be generated between the solder resist 61a and the wiring board 10.

[0098] In addition, in the third embodiment, similarly to the modified example of the first embodiment, the bonding surface 16 of each wiring board 10 of the plurality of wiring boards 10 may include two first corners 16a adjacent to each other and two second corners 16b adjacent to each other, and the first bonding material S31 may be symmetrically missing at the two second corners 16b. In addition, in the third embodiment, similarly to the second embodiment, a non-bonding processed portion ( Fig. 10A and Fig. 10B The solder resist 52a of the second conductor layer 52 is shown.

[0099] In the third embodiment described above, the same effects as those of the first embodiment can be obtained with regard to the same matters as those of the first embodiment, namely, the effects of preventing damage to the wiring board 10 caused by deformation of the heat dissipation base 60 during fastening while ensuring heat dissipation properties.

[0100] In the third embodiment, the heat dissipation base 60 has the solder resist 61 a (an example of a non-joining processed portion) applied to the region of the first surface 61 that faces the second corner portion 16 b .

[0101] Thus, at the location of the wiring board 10 Figure 1In the second corner 16b of the four corners A1 of the wiring board area A shown, the solder resist 61a (heat sink 60) does not bond with the wiring board 10, so the wiring board 10 does not follow the deformation of the heat sink 60 near the fastening hole 23. Therefore, at the second corner 16b, the second conductor layer 12 does not need to be missing, but by a simple process using the solder resist 61a, the wiring board 10 and the heat sink 60 will not bond, even if the first bonding material S31 is located at the second corner 16b, and damage to the wiring board 10 can be more reliably prevented.

[0102] Similarly, the solder resist 61a may be arranged in a manner to surround the second conductor layer 12 at a portion of the heat dissipation base 60 that is opposite to the portion of the back side of the wiring board 10 where the second conductor layer 12 is not present. In this case, the portion to be joined with the first bonding material S31 can be reliably controlled. In particular, when the solder resist 61a is arranged only at the boundary between the second corner 16b and the region to be joined with the first bonding material S31, the first bonding material S31 may also go over the solder resist 61a and be arranged at the second corner 16b, causing the second corner 16b to be joined with the heat dissipation base 60. It is desirable to cover the entire vicinity of the second corner 16b with the solder resist 61a to prevent the first bonding material S31 from going over the solder resist 61a and coming to the vicinity of the second corner 16b. The smearing (coating of graphite) performed with a pencil is also the same as the solder resist 61a.

[0103] <Fourth Implementation Method>

[0104] Fig. 12A and Fig. 12B The semiconductor module 4 according to the fourth embodiment is shown. Figure 1 The II-II sectional view corresponds to the sectional view at the position.

[0105] In the semiconductor module 4 of the present fourth embodiment, at the second corner 16b where the wiring board 70 and the heat sink 80 are not joined by the first joining material S41, a plurality of wiring boards 70 and the heat sink 80 are joined by the second joining material S2 having more elasticity than the first joining material S41. The other matters are the same as those of the first embodiment described above, so the reference numerals other than the wiring board 70, the second conductor layer 72, the solder resist 72a, the heat sink 80, the first surface 81, the solder resist 81a and the first joining material S41 are shown in the figure. Fig. 12A and Fig. 12B The same reference numerals as those in the above-mentioned first embodiment are given and the description thereof will be omitted.

[0106] like Fig. 12AAs shown, at the second corner 16b where the wiring board 70 and the heat sink 80 are not joined by the first joining material S41, as an example of a non-joined processed portion, solder resists 72a and 81a are provided on the second conductor layer 72 and the first surface 81 of the heat sink 80, respectively. Furthermore, the second joining material S2 is arranged between these solder resists 72a and 81a.

[0107] The solder resist 72a and 81a will not be bonded to the first bonding material S41, and the first bonding material S41 is difficult to enter between the solder resist 72a and 81a. Therefore, after the first bonding material S41 is arranged and before the sealing resin is injected, it is preferable to insert the second bonding material S2 between the solder resist 72a and 81a. The second bonding material S2 has elasticity compared to the first bonding material S41 to prevent the wiring board 70 from following the deformation of the heat dissipation base 80. In addition, the second bonding material S2 preferably has a higher thermal conductivity than the sealing resin.

[0108] like Fig. 12B As shown, when the heat dissipation base 80 is installed on the cooler 110 using the screw 120, even if the second surface 22 of the heat dissipation base 80 is deformed in the direction changing from a convex curved surface to a flat surface, the second bonding material S2 is stretched at the second corner 16b, and the wiring board 70 is not easy to follow the deformation of the heat dissipation base 80 near the fastening hole 23.

[0109] In addition, in the fourth embodiment, similarly to the modified example of the first embodiment, the bonding surface 16 of each wiring board 70 of the plurality of wiring boards 70 may include two first corners 16a adjacent to each other and two second corners 16b adjacent to each other, and the first bonding material S41 may be symmetrically missing at the two second corners 16b. In this case, it is preferred that the second bonding material S2 is provided at least at the second corners 16b of the four corners A1 of the wiring board region A. In addition, in the fourth embodiment, solder resists 72a and 81a are provided on the wiring board 70 and the heat dissipation base 80, but if the first bonding material S41 can be arranged in a manner that does not enter the second corner 16b, the solder resists 72a and 81a can be omitted.

[0110] In the fourth embodiment described above, the same effects as those of the first embodiment can be obtained, namely, the effects of preventing damage to the wiring board 70 caused by deformation of the heat dissipation base 80 during fastening while ensuring heat dissipation properties.

[0111] In the fourth embodiment, the semiconductor module 4 further includes a second bonding material S2 that bonds the plurality of wiring boards 70 and the heat dissipation base 80 at the second corner portion 16 b and has greater elasticity than the first bonding material S41 .

[0112] Thus, at the location of the wiring board 70 Figure 1 At the second corners 16b near the fastening holes 23 at the four corners A1 of the wiring board region A shown in the figure, the wiring board 70 is less likely to follow the deformation of the heat dissipation base 80. Therefore, it is possible to prevent damage to the wiring board 70 with a simple structure without cutting off the second conductor layer 12. In addition, if the second bonding material S2 has a higher thermal conductivity than the sealing resin, the heat dissipation from the wiring board 70 to the heat dissipation base 80 can be improved at the second corners 16b.

[0113] The semiconductor modules 1 to 4 of the first to fourth embodiments described above are not limited to the above descriptions, and various changes, substitutions, and deformations can be made within the scope of the main idea of ​​the technology. Moreover, if the technology can be realized in other ways due to technological progress or other derived technologies, the method can also be used for implementation. Therefore, the claims cover all embodiments that can be included in the scope of the technology.

[0114] Hereinafter, a part of the invention described in the specification and drawings of this application will be supplemented.

[0115] <Additional Note 1>

[0116] A semiconductor module, characterized in that:

[0117] The semiconductor module has:

[0118] a plurality of wiring boards on which semiconductor elements are mounted;

[0119] a heat dissipation base having a first surface to which the plurality of wiring boards are bonded and a second surface located on a side opposite to the first surface; and

[0120] a first bonding material for bonding the plurality of wiring boards to the heat dissipation base,

[0121] The heat dissipation base is warped so that the second surface becomes a convex curved surface.

[0122] At least a plurality of corners of the heat dissipation base are provided with fastening holes,

[0123] The bonding surface of each of the plurality of wiring boards facing the heat dissipation base includes: a first corner portion, which is bonded to the heat dissipation base using the first bonding material; and a second corner portion, which is not bonded to the heat dissipation base using the first bonding material.

[0124] The first bonding material bonds the plurality of wiring boards to the heat dissipation base such that the second corners of the wiring boards are located at four corners of a wiring board region including the entirety of the plurality of wiring boards.

[0125] <Note 2>

[0126] The semiconductor module according to Supplementary Note 1 is characterized in that

[0127] The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side.

[0128] The second conductor layer is missing at the second corner.

[0129] <Addendum 3>

[0130] The semiconductor module according to Supplementary Note 2 is characterized in that

[0131] The bonding surface of each of the plurality of wiring boards includes two first corner portions adjacent to each other and two second corner portions adjacent to each other,

[0132] The first bonding material is symmetrically missing at the two second corners.

[0133] <Addendum 4>

[0134] The semiconductor module according to Supplementary Note 1 is characterized in that

[0135] The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side.

[0136] The second conductor layer has a non-bonding processed portion applied to the second corner portion.

[0137] <Addendum 5>

[0138] The semiconductor module according to Supplement 1 or 4, characterized in that

[0139] The heat dissipation base has a non-bonding processed portion in a region of the first surface that faces the second corner portion.

[0140] <Addendum 6>

[0141] The semiconductor module according to any one of Supplementary Notes 1 to 5, characterized in that:

[0142] The semiconductor module further includes a second bonding material that bonds the plurality of wiring boards to the heat dissipation base at the second corner and has greater elasticity than the first bonding material.

[0143] <Addendum 7>

[0144] The semiconductor module according to any one of Supplementary Notes 1 to 6, characterized in that:

[0145] The semiconductor module further includes a main current wiring and a control wiring,

[0146] The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side.

[0147] The first conductor layer is connected only to the control wiring among the main current wiring and the control wiring at the four corners of the wiring board region, and the main current does not flow.

[0148] <Addendum 8>

[0149] The semiconductor module according to any one of Supplementary Notes 1 to 7, characterized in that:

[0150] The heat dissipation base has a local protrusion on the second surface, and when the position where the diagonal line connecting the fastening holes intersects with the two ends of the area corresponding to the wiring board area is set as the reference position, and the middle position between the two reference positions is set as the central position, the local protrusion is the position of the convex curved surface with the largest protrusion relative to the auxiliary line connecting the two reference positions and the central position.

[0151] The first bonding material is located at a position spaced apart from the local protrusion of the heat dissipation base toward the central position.

[0152] Industrial Applicability

[0153] As described above, the present invention has the effect of preventing damage to the wiring board due to deformation during fastening of the heat dissipation base while ensuring heat dissipation performance, and is particularly useful for industrial or electrical inverter devices.

Claims

1. A semiconductor module, characterized in that: The semiconductor module has: a plurality of wiring boards on which semiconductor elements are mounted; a heat dissipation base having a first surface to which the plurality of wiring boards are bonded and a second surface located on a side opposite to the first surface; and a first bonding material for bonding the plurality of wiring boards to the heat dissipation base, The heat dissipation base is warped so that the second surface becomes a convex curved surface. At least a plurality of corners of the heat dissipation base are provided with fastening holes, The bonding surface of each of the plurality of wiring boards facing the heat dissipation base includes: a first corner portion, which is bonded to the heat dissipation base using the first bonding material; and a second corner portion, which is not bonded to the heat dissipation base using the first bonding material. The first bonding material bonds the plurality of wiring boards to the heat dissipation base such that the second corners of the wiring boards are located at four corners of a wiring board region including the entirety of the plurality of wiring boards.

2. The semiconductor module according to claim 1, characterized in that The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side. The second conductor layer is missing at the second corner.

3. The semiconductor module according to claim 2, characterized in that The bonding surface of each of the plurality of wiring boards includes two first corner portions adjacent to each other and two second corner portions adjacent to each other, The first bonding material is symmetrically missing at the two second corners.

4. The semiconductor module according to claim 1, characterized in that The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side. The second conductor layer has a non-bonding processed portion applied to the second corner portion.

5. The semiconductor module according to claim 1, characterized in that The heat dissipation base has a non-bonding processed portion in a region of the first surface that faces the second corner portion.

6. The semiconductor module according to claim 1, characterized in that The semiconductor module further includes a second bonding material that bonds the plurality of wiring boards to the heat dissipation base at the second corner and has greater elasticity than the first bonding material.

7. The semiconductor module according to claim 1, characterized in that The semiconductor module further includes a main current wiring and a control wiring, The wiring board includes an insulating layer, a first conductor layer provided on a surface of the insulating layer on the semiconductor element side, and a second conductor layer provided on a surface of the insulating layer on the heat sink side. The first conductor layer is connected only to the control wiring among the main current wiring and the control wiring at the four corners of the wiring board region, and the main current does not flow.

8. The semiconductor module according to claim 1, characterized in that The heat dissipation base has a local protrusion on the second surface, and when the position where the diagonal line connecting the fastening holes intersects with the two ends of the area corresponding to the wiring board area is set as the reference position, and the middle position between the two reference positions is set as the central position, the local protrusion is the position of the convex curved surface with the largest protrusion relative to the auxiliary line connecting the two reference positions and the central position. The first bonding material is located at a position spaced apart from the local protrusion of the heat dissipation base toward the central position.

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