Semiconductor device and heat sink

Abstract

To provide a semiconductor device that suppresses the generation of stress differences within heat dissipation material when fastening a semiconductor module to a heat sink using fastening members, thereby preventing stress-induced cracks in a semiconductor module's insulating substrate, etc.SOLUTION: A semiconductor device includes a semiconductor module having a heat dissipation plate, a heat sink having a mounting surface onto which the semiconductor module is mounted, and a heat dissipation material having flexibility interposed between the heat dissipation plate and the heat sink. The semiconductor module and the heat sink are fastened by fastening members. The semiconductor module and the heat sink each have a fastening portion to which the fastening members are attached. A spacer is provided between the semiconductor module and the heat sink at the fastening portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor device and a heat sink. [Background technology]

[0002] A conventional technique is known in which heat generated by a semiconductor module is dissipated by interposing a flexible heat dissipation material, such as a heat dissipation sheet or grease, between the heat sink and the semiconductor module. Another conventional technique is known in which the semiconductor module and the heat sink are fastened together with fastening members, such as screws.

[0003] The structure of a conventional semiconductor module and heat sink is described, for example, in Patent Document 1. Patent Document 1 discloses a power semiconductor module provided with a semiconductor module having a base plate and a heat sink having a mounting surface on which the semiconductor module is mounted. In addition, thermally conductive grease, which is a heat dissipation material, is interposed between the base plate provided on the underside of the semiconductor module and the heat sink, and the semiconductor module and the heat sink are fastened together with screws. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-129 Summary of the Invention [Problem to be solved by the invention]

[0005] In the power semiconductor module described in Patent Document 1, axial force is generated when the semiconductor module and the heat sink are fastened together with screws, and the axial force is concentrated at the fastening point. The concentration of axial force at the fastening point causes the fastening point of the semiconductor module to sink relative to the center of the semiconductor module, which is located away from the fastening point. This causes a stress difference to occur between the vicinity of the fastening point and the center, which is located away from the fastening point, inside the heat dissipation material interposed between the base plate provided on the underside of the semiconductor module and the heat sink. This stress difference inside the heat dissipation material poses a problem of cracks occurring in relatively inflexible components, such as insulating substrates, that make up the semiconductor module.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a semiconductor device that can suppress the occurrence of stress differences inside the heat dissipation material when a semiconductor module and a heat sink are fastened with a fastening member, and can suppress the occurrence of cracks due to stress in the insulating substrate of the semiconductor module, etc. [Means for solving the problem]

[0007] The semiconductor device according to the present disclosure comprises a semiconductor module having a heat sink, a heat sink having a mounting surface on which the semiconductor module is mounted, and a flexible heat dissipation material interposed between the heat sink and the heat sink, wherein the semiconductor module and the heat sink are fastened together by a fastening member, the semiconductor module and the heat sink each having a fastening portion to which the fastening member is attached, and a spacer between the semiconductor module and the heat sink at the fastening portion. [Effects of the Invention]

[0008] According to the semiconductor device of the present disclosure, when a semiconductor module and a heat sink are fastened together using a fastening member, the occurrence of stress differences within the heat dissipation material can be suppressed, and cracks due to stress can be suppressed from occurring in the insulating substrate of the semiconductor module, etc. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of a semiconductor device according to a first embodiment. [Figure 2] 1 is a schematic top view of a semiconductor device according to a first embodiment. [Figure 3] 1 is a schematic cross-sectional view of a semiconductor device according to a first embodiment. [Figure 4] FIG. 10 is a schematic cross-sectional view of a semiconductor device according to a second embodiment. [Figure 5] FIG. 10 is a schematic top view of a semiconductor device according to a second embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view of a semiconductor device according to a first modification of the second embodiment. [Figure 7] FIG. 10 is a schematic top view of a semiconductor device according to a first modification of the second embodiment. [Figure 8] FIG. 10 is a schematic cross-sectional view of a semiconductor device according to a second modification of the second embodiment. [Figure 9] FIG. 10 is a schematic top view of a semiconductor device according to a second modification of the second embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view of a semiconductor device according to a third modification of the second embodiment. [Figure 11] FIG. 10 is a schematic top view of a semiconductor device according to a third modification of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Introduction> One side in a direction parallel to the depth direction of a semiconductor device is referred to as "top" and the other side as "bottom." Of the two main surfaces of a substrate, layer, or other member, one surface is referred to as the top surface and the other surface is referred to as the bottom surface. The directions of "top" and "bottom" are not limited to the direction of gravity or the directions when the semiconductor device is mounted.

[0011] Furthermore, the drawings are schematic, and the relative sizes and positions of images shown in different drawings are not necessarily accurately depicted and may be changed as appropriate. In the following description, similar components are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions thereof may be omitted.

[0012] Embodiment 1 The first embodiment will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a semiconductor device 100 according to the first embodiment. FIG. 2 is a schematic top view of the semiconductor device 100 according to the first embodiment. FIG. 1 shows a cross section taken along the dashed-dotted line X-X in FIG. 2. For convenience of explanation, FIG. 1 also shows a fastening portion 6, a fastening member 7, and a spacer 22 in addition to the cross-sectional view taken along the dashed-dotted line X-X in FIG. 2. The spacer 22 is indicated by a dotted line in FIG. 2.

[0013] The configuration of a semiconductor device 100 will be described with reference to Figures 1 and 2. As shown in Figure 1, the semiconductor device 100 includes a semiconductor module 10, a heat sink 20 having a mounting surface 21 on which the semiconductor module 10 is mounted, and a heat dissipation material interposed between a heat sink 20 and a heat sink 1 of the semiconductor module 10. First, the detailed configuration of the semiconductor module 10 will be described with reference to Figure 1. The semiconductor module 10 includes a heat sink 1 and an insulating substrate 2.

[0014] The heat sink 1 is made of a material having electrical and thermal conductivity, such as a metal material such as copper or aluminum.

[0015] The insulating substrate 2 is provided on the upper surface of the heat sink 1. The insulating substrate 2 is mounted on the upper surface of the heat sink 1 by, for example, soldering. The insulating substrate 2 is made of an insulating resin, for example, ceramic.

[0016] 1, a metal pattern 3 may be provided on the upper surface of the insulating substrate 2. The metal pattern 3 is mounted on the upper surface of the insulating substrate 2 by, for example, soldering. The metal pattern 3 is made of a highly conductive metal such as copper.

[0017] As shown in FIG. 1, a semiconductor chip 4 is mounted on a metal pattern 3. The semiconductor chip 4 may be made of Si or a wide bandgap semiconductor such as SiC, GaN, or Ga2O3. The type of device of the semiconductor chip 4 is not particularly limited, but may be a switching element 4a such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and may also be a free wheel element 4b. For example, as shown in FIG. 2, the semiconductor chip 4 may be made of a plurality of switching elements 4a and a plurality of free wheel elements 4b. As shown in FIG. 2, the plurality of elements are arranged side by side and connected by wires (not shown). The plurality of switching elements 4a and the plurality of free wheel elements 4b are arranged one-to-one above and below. The plurality of free wheel elements 4b are connected in anti-parallel to the plurality of switching elements 4a, so that a uniform current flows through them.

[0018] 1, the semiconductor module 10 may have a case material on its outer periphery. The case material 5 is made of an insulating resin and is bonded to the heat sink 1. As shown in FIG. 2, the case material 5 may be provided so as to surround the outer periphery of the insulating substrate 2 and the like provided on the heat sink 1.

[0019] 1, the semiconductor module 10 is provided with fastening portions 6. The fastening portions 6 provided on the semiconductor module 10 side are first fastening portions 6a, and in this embodiment, as shown in FIG. 1, the first fastening portions 6a are provided on the case material 5. Fastening members 7 for fastening the semiconductor module 10 and the heat sink 20 are attached to the fastening portions 6. As shown in FIG. 2, the first fastening portions 6a are preferably provided at the four outer corners of the semiconductor module 10.

[0020] 1, the semiconductor module 10 may be sealed with a sealing material 8. As shown in FIG. 1, in this embodiment, the sealing material 8 is provided inside the case material 5. The sealing material 8 is made of, for example, an insulating gel or resin.

[0021] As described above, the semiconductor module 10 is configured. Note that the first fastening portion 6a on the semiconductor module 10 side may be provided on the heat sink 1, as shown in FIG.

[0022] Next, the heat dissipation material 30 will be described with reference to FIG. 1. As shown in FIG. 1, the heat dissipation material 30 is provided so as to be interposed between the heat sink 20 and the heat sink 1 of the semiconductor module 10. The heat dissipation material 30 is made of a flexible material with high thermal conductivity, such as thermal grease or a thermal sheet. The thickness of the heat dissipation material 30 is approximately 10 μm to 100 μm in the case of a thermal sheet, and the amount of application of thermal grease is approximately 50 μm to 100 μm. The heat dissipation material 30 only needs to be provided directly below the heat sink 1, and does not have to be provided directly below the case material 5.

[0023] Next, the heat sink 20 will be described in detail with reference to FIGS. 1 and 2. As shown in FIG. 1, the heat sink 20 has a mounting surface 21 on which a semiconductor module 10 is mounted via a flexible heat dissipation material 30. The heat sink 20 is made of a metal such as aluminum, which has high thermal conductivity. The heat sink 20 may also have fins formed on its underside. The heat sink 20 also has a fastening portion 6 to which a fastening member 7 is attached for fastening to the semiconductor module 10. The fastening portion 6 provided on the heat sink 20 side is referred to as a second fastening portion 6b. Furthermore, as shown in FIG. 1, a spacer 22 is provided between the semiconductor module 10 and the heat sink 20 in the fastening portion 6. As shown in FIG. 1, the spacer 22 is preferably provided on the second fastening portion 6b and in contact with the mounting surface 21 of the heat sink 20. Alternatively, the spacer 22 may be provided integrally with the heat sink 20. As shown in FIG. 2, the second fastening portion 6b and the spacer 22 are preferably provided at the four outer corners of the heat sink 20. Furthermore, before fastening the fastening member 7, the height of the spacer 22 is set to be equal to or less than the maximum thickness of the heat dissipation material 30. As described above, since the thickness of the heat dissipation material 30 is about several tens of micrometers, the height of the spacer 22 is also set to be equal to or less than the maximum thickness of the heat dissipation material 30, also about several tens of micrometers. This allows the heat dissipation material 30 to be in close contact with the mounting surface 21 of the heat sink 20 and the semiconductor module 10, ensuring heat dissipation. Note that, as shown in FIGS. 1 and 2, the shape of the spacer 22 may be a cube, and any shape is possible. Furthermore, as shown in FIGS. 1 and 2, it is preferable that the width of the spacer 22 be set to be wider than the width of the fastening member 7 with some margin.

[0024] Although the above describes the case where the spacer 22 is provided on the second fastening portion 6b of the heat sink 20, the spacer 22 may also be provided on the first fastening portion 6a of the semiconductor module 10. For example, the spacer 22 may be provided in contact with the lower surface of the case material 5, or may be provided integrally with the case material 5. However, when thermal grease, which is the heat dissipation material 30, is applied to the semiconductor module 10 side, it is preferable to provide the spacer 22 in contact with the mounting surface 21 of the heat sink 20, because this makes it easier to apply the thermal grease, which is the heat dissipation material 30, to the lower surface of the heat sink 1 of the semiconductor module 10.

[0025] As described above, the semiconductor module 10 and the heat sink 20 each have a fastening portion 6, and the same fastening member 7 is inserted into each fastening portion 6, and the semiconductor module 10 and the heat sink 20 are fastened together by the fastening member 7. The fastening portion 6 may be a screw hole, and the fastening member 7 may be a screw, a nut, or the like. As described above, it is preferable that each fastening portion 6 is provided at each of the four outer corners, but it is sufficient that they are provided in at least two or more locations, and this may be selected appropriately depending on the size of the semiconductor device, etc. The fastening member 7 may also be inserted from the underside of the heat sink 20.

[0026] The semiconductor device 100 of this embodiment is configured as described above. By providing the spacer 22 between the semiconductor module 10 and the heat sink 20 at the fastening portion 6, it is possible to suppress the occurrence of a stress difference inside the heat dissipation material 30 when the semiconductor module 10 and the heat sink 20 are fastened together with the fastening member 7, and to suppress the occurrence of cracks due to stress in the insulating substrate 2 of the semiconductor module 10, etc. The reason for this will be explained below.

[0027] In conventional semiconductor devices, the mounting surface 21 of the heat sink 20 is flat, so the fastening portion 6 of the semiconductor module 10 sinks into the center of the semiconductor module 10, which is distant from the fastening portion 6. This causes a stress difference to occur inside the heat dissipation material 30 between the vicinity of the fastening portion 6 and the center distant from the fastening portion 6. The stress difference generated inside the heat dissipation material 30 causes cracks to occur in relatively inflexible members such as the insulating substrate 2 that constitute the semiconductor module 10. For example, when the first fastening portion 6a is provided on the case material 5, cracks occur in the case material 5, and when the first fastening portion 6a is provided on the heat sink 1, cracks occur in the insulating substrate 2.

[0028] In the semiconductor device 100 of this embodiment, the spacers 22 are provided in the fastening portions 6, thereby preventing the fastening portions 6 of the semiconductor module 10 from sinking into the center of the semiconductor module 10 that is distant from the fastening portions 6 by the height of the spacers 22. Therefore, the difference in stress that occurs in the heat dissipation material 30 between the vicinity of the fastening portions 6 and the center that is distant from the fastening portions 6 can be alleviated, and therefore cracks can be prevented from occurring in relatively inflexible members that constitute the semiconductor module 10, such as the insulating substrate 2, and the reliability of the semiconductor device can be improved.

[0029] Next, a description will be given of a manufacturing method for the semiconductor device 100 of this embodiment. The manufacturing method for the semiconductor device 100 of this embodiment is basically the same as the manufacturing method for a conventional semiconductor device, except for the process of forming the spacers of the heat sink 20, and therefore the process of forming the semiconductor module 10 will be omitted from the description.

[0030] The method for manufacturing the semiconductor device 100 includes a spacer forming step, a heat dissipation material forming step, and a fastening step.

[0031] First, the spacer formation step will be described. As an example of a method for forming the spacer 22, a case in which the spacer 22 is provided integrally with the heat sink 20 will be described. In the heat sink 20 having a flat mounting surface 21, the mounting surface 21 except for the second fastening portion 6b is ground down using, for example, a micro grinder. In this way, the spacer 22 can be formed on the second fastening portion 6b.

[0032] When the spacer 22 is provided as a separate member from the heat sink 20, the spacer 22 may be formed by separately placing the spacer 22 on the second fastening portion 6b of the mounting surface 21 of the heat sink 20 having a flat mounting surface 21. When the spacer 22 is provided on the first fastening portion 6a of the semiconductor module 10, the spacer 22 may be formed on the first fastening portion 6a by molding the semiconductor module 10 side using the method described above.

[0033] Next, the heat dissipation material forming step will be described. A flexible heat dissipation material 30 is formed on at least the lower surface of the heat dissipation plate 1 of the semiconductor module 10. Thermal grease may be applied to the lower surface of the heat dissipation plate 1, or a thermal sheet may be attached to the lower surface of the heat dissipation plate 1.

[0034] Next, the fastening process will be described. First, the semiconductor module 10 is mounted on the heat sink 20 via the heat dissipation material 30. Next, fastening members 7 are inserted into fastening portions 6 provided on the semiconductor module 10 and the heat sink 20. Next, the heat sink 20 and the semiconductor module 10 are fastened together with the fastening members 7. This allows the semiconductor module 10 to be tightly attached to the heat sink 20 and the heat dissipation material 30.

[0035] The semiconductor device 100 is manufactured through the above-described steps. As described above, the manufacturing method for the semiconductor device 100 of this embodiment further includes a spacer formation step, in which the spacers 22 are formed in the fastening portions 6. By forming the spacers 22, it is possible to prevent the fastening portions 6 of the semiconductor module 10 from sinking into the center of the semiconductor module 10 that is distant from the fastening portions 6 by the height of the spacers 22 during the fastening step. Therefore, it is possible to alleviate the stress difference that occurs in the heat dissipation material 30 between the vicinity of the fastening portions 6 and the center that is distant from the fastening portions 6, thereby preventing cracks from occurring in relatively inflexible members that constitute the semiconductor module 10, such as the insulating substrate 2, and thus improving the reliability of the semiconductor device.

[0036] Embodiment 2 A semiconductor device 200 according to a second embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic cross-sectional view of the semiconductor device 200 according to the second embodiment. FIG. 5 is a schematic top view of the semiconductor device 200 according to the second embodiment. FIG. 4 shows a cross section taken along the dashed-dotted line X-X in FIG. 5. For ease of explanation, FIG. 4 shows a fastening portion 6, a fastening member 7, and a spacer 22 in addition to the cross-sectional view taken along the dashed-dotted line X-X in FIG. 5. The spacer 22 and the protrusion 23 are indicated by dotted lines in FIG. 5.

[0037] The semiconductor device 200 of the second embodiment further includes a protrusion 23 on the mounting surface 21 of the heat sink 20. As shown in FIGS. 4 and 5, the protrusion 23 is provided on the mounting surface 21 of the heat sink 20 at a position corresponding to the semiconductor chip 4. The height of the protrusion 23 is equal to or less than the height of the spacer 22. This embodiment differs from the first embodiment in that the protrusion 23 is further provided on the mounting surface 21 of the heat sink 20. The protrusion 23 only needs to be provided at a position on the mounting surface 21 of the heat sink 20 corresponding to at least the semiconductor chip 4. As shown in FIG. 5, the protrusion 23 may be provided only at a position on the mounting surface 21 of the heat sink 20 corresponding to the semiconductor chip 4. The reason for this will be described later. For example, as shown in FIG. 5, if one set consisting of a plurality of switching elements 4a and a plurality of reflux elements 4b of the semiconductor chip 4 is provided in two separate locations, the protrusion 23 may also be provided in two separate locations corresponding to one set consisting of a plurality of switching elements 4a and a plurality of reflux elements 4b of the semiconductor chip 4. 4 and 5, the shape of the protrusion 23 is preferably a rectangular parallelepiped to match the shape of the semiconductor chip 4, but the shape is arbitrary. Also, the protrusion 23 is preferably provided integrally with the heat sink 20. This ensures better thermal conductivity than if the protrusion 23 were provided separately on the heat sink 20, and improves heat dissipation.

[0038] As described above, the semiconductor device 200 of the second embodiment is configured. As in the first embodiment, by providing the spacer 22 between the semiconductor module 10 and the heat sink 20 at the fastening portion 6, it is possible to suppress the occurrence of a stress difference inside the heat dissipation material 30 when the semiconductor module 10 and the heat sink 20 are fastened together with the fastening member 7, and to suppress the occurrence of cracks due to stress in the insulating substrate 2 of the semiconductor module 10, etc.

[0039] Furthermore, by providing a protrusion 23 on the mounting surface 21 of the heat sink 20 at a position corresponding to the semiconductor chip 4, it is possible to improve the heat dissipation performance of the semiconductor module 10. The reason for this will be explained below.

[0040] The highest heat dissipation performance is required directly below the semiconductor chip 4, which is the heat source of the semiconductor module 10. In order to improve the heat dissipation performance, it is necessary to improve the contact between the heat sink 1 of the semiconductor module 10 and the heat dissipation material 30 and the heat sink 20 directly below the semiconductor chip 4.

[0041] In the semiconductor device 200 of the second embodiment, a protrusion 23 is provided on the mounting surface 21 of the heat sink 20 at a position corresponding to the semiconductor chip 4. This reduces the distance between the heat sink 1 and the heat sink 20 directly below the semiconductor chip 4, thereby increasing the compressibility of the heat dissipation material and improving contact. Because of the improved contact, it is possible to improve heat dissipation directly below the mounted semiconductor chip 4, which is the heat source of the semiconductor module 10.

[0042] Furthermore, the height of the protrusions 23 is set equal to or less than the height of the spacers 22. When the semiconductor module 10 is fastened to the heat sink 20 via the heat dissipation material 30, even if the spacers 22 are provided at the fastening portions 6, if the height of the protrusions 23 is greater than the height of the spacers 22, the fastening portions 6 of the semiconductor module 10 sink toward the center of the semiconductor module 10, which is farther from the fastening portions 6. As a result, a stress difference occurs inside the heat dissipation material between the protrusions 23 provided on the heat sink 20 and the spacers 22 provided on the fastening portions 6. This causes cracks to occur in the relatively inflexible case material 5 or insulating substrate 2, resulting in reduced reliability. Therefore, by setting the height of the protrusions 23 equal to or less than the height of the spacers 22, the stress difference between the protrusions 23 and the spacers 22 inside the heat dissipation material can be suppressed. This prevents cracks from occurring in the case material 5 or the insulating substrate 2, thereby maintaining reliability and ensuring heat dissipation.

[0043] Next, modifications of the second embodiment will be described with reference to FIGS. 6 to 11. First, modification 1 will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic cross-sectional view of a semiconductor device according to modification 1. FIG. 7 is a schematic top view of a semiconductor device according to modification 1. Note that FIG. 6 shows a cross section taken along dashed line X-X in FIG. 7. Note that FIG. 6 is a diagram in which fastening portion 6, fastening member 7, and spacer 22 are added to the cross-sectional view taken along dashed line X-X in FIG. 7 for ease of explanation. Spacer 22 and protrusion 23 are indicated by dotted lines in FIG. 7.

[0044] As shown in Fig. 6, the protrusions 23 may be provided so that they become higher as they move toward the center of the semiconductor module 10. The maximum height of the protrusions 23 is set lower than the height of the spacers 22. As shown in Fig. 6, the protrusions 23 may be provided in a stepped shape. As shown in Fig. 6, the starting point of each step of the stepped protrusions 23 may be provided on the side surface on the outer periphery of the corresponding semiconductor chip 4.

[0045] The multiple semiconductor chips 4 mounted on the semiconductor module 10 are each subject to thermal interference due to the heat generated by the other surrounding semiconductor chips 4. Therefore, the semiconductor chips 4 located closer to the center of the semiconductor module 10 have higher temperatures and therefore require higher heat dissipation capabilities.

[0046] In the semiconductor device of Modification 1, the protrusions 23 are provided so as to become higher toward the center of the semiconductor module 10, and therefore the contact between the heat sink 1 of the semiconductor module 10 and the heat dissipation material 30 and the heat sink 20 improves toward the center of the semiconductor module 10. Therefore, it is possible to selectively improve heat dissipation toward the center of the module where the temperature becomes high.

[0047] Next, Modification 2 will be described with reference to Figures 8 and 9. Figure 8 is a schematic cross-sectional view of a semiconductor device according to Modification 1. Figure 9 is a schematic top view of a semiconductor device according to Modification 1. Note that Figure 8 shows a cross section taken along dashed line X-X in Figure 9. Note that for ease of explanation, Figure 8 is a diagram in which fastening portion 6, fastening member 7, and spacer 22 are added to the cross-sectional view taken along dashed line X-X in Figure 9. Spacer 22 and protrusion 23 are indicated by dotted lines in Figure 9.

[0048] 8, in the semiconductor device of Modification 2, similar to Modification 1, the protrusions 23 are provided so that they become higher toward the center of the semiconductor module 10. Furthermore, as shown in Figures 8 and 9, in the semiconductor device of Modification 2, the protrusions 23 are provided only at positions corresponding to each of the multiple semiconductor chips 4. The maximum height of the protrusions 23 is set lower than the height of the spacers 22.

[0049] In the semiconductor device of Modification 2, similarly to the semiconductor device of Modification 1, the protrusions 23 are provided so as to become higher toward the center of the semiconductor module 10, and therefore the contact between the heat sink 1 of the semiconductor module 10 and the heat dissipation material 30 and the heat sink 20 improves toward the center of the semiconductor module 10. Therefore, it is possible to selectively improve heat dissipation toward the center of the module where the temperature becomes high.

[0050] Furthermore, in the semiconductor device of Modification 2, the protrusions 23 are provided only at positions corresponding to each of the multiple semiconductor chips 4. When the heat dissipation material 30 is fastened, it is further compressed at the locations where the protrusions 23 are provided. Therefore, the wider the area where the protrusions 23 are provided on the mounting surface 21 of the heat sink 20, the more the heat dissipation material 30 is compressed, and greater stress is generated inside the heat dissipation material 30. Therefore, by providing the protrusions 23 only at positions corresponding to each of the multiple semiconductor chips 4, it is possible to suppress the stress generated inside the heat dissipation material 30 compared to Modification 1, and it is also possible to maintain heat dissipation performance directly below the semiconductor chip 4.

[0051] Next, Modification 3 will be described with reference to Figures 10 and 11. Figure 10 is a schematic cross-sectional view of a semiconductor device according to Modification 3. Figure 11 is a schematic top view of a semiconductor device according to Modification 3. Note that Figure 10 shows a cross section taken along dashed line X-X in Figure 11. Note that for ease of explanation, Figure 10 is a diagram in which fastening portion 6, fastening member 7, and spacer 22 are added to the cross-sectional view taken along dashed line X-X in Figure 11. Spacer 22 and protrusion 23 are indicated by dotted lines in Figure 11.

[0052] 10 and 11, in the semiconductor device of Modification 3, similar to the semiconductor device of Modification 2, the protrusions 23 are provided so that they become higher toward the center of the semiconductor module 10, and are provided only at positions corresponding to each of the multiple semiconductor chips 4. Furthermore, in the semiconductor device of Modification 3, the size of the top surface of the protrusions 23 is set smaller than the size of the bottom surface of the semiconductor chip 4. The maximum height of the protrusions 23 is set smaller than the height of the spacers 22.

[0053] In the semiconductor device of Modification 3, similarly to the semiconductor devices of Modifications 1 and 2, the protrusions 23 are provided so as to become higher toward the center of the semiconductor module 10, and therefore the contact between the heat sink 1 of the semiconductor module 10 and the heat dissipation material 30 and the heat sink 20 improves toward the center of the semiconductor module 10. Therefore, it is possible to selectively improve heat dissipation toward the center of the module where the temperature becomes high.

[0054] Furthermore, in the semiconductor device of variant 3, like the semiconductor device of variant 2, the convex portions 23 are provided only at positions corresponding to each of the multiple semiconductor chips 4, so that stress generated inside the heat dissipation material 30 can be suppressed and heat dissipation properties can be maintained directly below the semiconductor chips 4.

[0055] Furthermore, in the semiconductor device of Modification 3, the size of the top surface of the protrusion 23 is set smaller than the size of the bottom surface of the semiconductor chip 4. This can further suppress stress generated inside the heat dissipation material 30. The size of the top surface of the protrusion 23 is preferably set smaller, with a lower limit of 80% of the size of the bottom surface of the semiconductor chip 4. If the size of the top surface of the protrusion 23 is made much smaller than the size of the bottom surface of the semiconductor chip 4, the contact area directly below the semiconductor chip 4 will decrease, thereby degrading heat dissipation. Therefore, by setting the size of the top surface of the protrusion 23 to a lower limit of 80% of the size of the bottom surface of the semiconductor chip 4, stress generated inside the heat dissipation material 30 can be further suppressed while maintaining heat dissipation performance. Furthermore, as shown in FIG. 11, the shape of the top surface of the protrusion 23 may be cross-shaped.

[0056] The configurations shown in the above embodiments are merely examples of the contents of the present disclosure and may be combined with other known technologies. Furthermore, it is also possible to combine the embodiments with each other and the modified examples with each other. Furthermore, it is also possible to omit or modify part of the configurations without departing from the scope of the present disclosure. [Explanation of symbols]

[0057] 1 heat sink, 2 insulating substrate, 3 metal pattern, 4 semiconductor chip, 5 case material, 6 fastening portion, 7 fastening member, 10 semiconductor module, 20 heat sink, 21 mounting surface, 22 spacer, 23 protrusion, 30 heat dissipation material, 100 200 semiconductor device

Claims

1. a semiconductor module having a heat sink; a heat sink having a mounting surface on which the semiconductor module is mounted; a flexible heat dissipation material interposed between the heat dissipation plate and the heat sink, the semiconductor module and the heat sink are fastened together by a fastening member; the semiconductor module and the heat sink each have a fastening portion to which the fastening member is attached, The semiconductor device further comprises a spacer between the semiconductor module and the heat sink at the fastening portion.

2. 2. The semiconductor device according to claim 1, wherein the height of the spacer is equal to or less than the maximum thickness of the heat dissipation material.

3. The semiconductor device according to claim 1 , wherein the spacer is provided in contact with the mounting surface of the heat sink.

4. 4. The semiconductor device according to claim 3, wherein the spacer is provided integrally with the heat sink.

5. the semiconductor module has a case material on its outer periphery, The semiconductor device according to claim 1 , wherein the fastening portion on the semiconductor module side is provided on the case material.

6. The semiconductor device according to claim 1 , wherein the fastening portion on the semiconductor module side is provided on the heat sink.

7. The semiconductor device according to claim 1 , wherein the fastening portions are provided in at least two places.

8. the semiconductor module has a semiconductor chip; the heat sink has a protrusion on the mounting surface at a position corresponding to the semiconductor chip, 2. The semiconductor device according to claim 1, wherein the height of the protrusion is equal to or less than the height of the spacer.

9. The semiconductor device according to claim 8 , wherein the protrusions are formed so as to become higher toward the center of the semiconductor module.

10. The semiconductor device according to claim 9 , wherein the protrusion is provided in a stepped shape.

11. 10. The semiconductor device according to claim 8, wherein the protrusion is provided only at a position corresponding to the semiconductor chip.

12. The semiconductor device according to claim 11 , wherein the size of the top surface of the convex portion is smaller than the size of the bottom surface of the semiconductor chip.

13. a mounting surface for mounting a semiconductor module via a flexible heat dissipation material; a fastening portion provided on the mounting surface to which a fastening member for fastening to the semiconductor module is attached; a spacer provided at the fastening portion.

14. The heat sink according to claim 13 , wherein the height of the spacer is equal to or less than the maximum thickness of the heat dissipation material before fastening.

15. The heat sink according to claim 13 , wherein the fastening portions are provided in at least two places.

16. the semiconductor module has a semiconductor chip; The heat sink according to claim 13 , further comprising a protrusion on the mounting surface at a position corresponding to the semiconductor chip, the protrusion having a height equal to or less than the height of the spacer.

17. The heat sink according to claim 16 , wherein the protrusions are formed so as to become higher toward the center of the semiconductor module.

18. The heat sink according to claim 17 , wherein the protrusions are provided in a stepped shape.

19. The heat sink according to claim 16 or 17, wherein the protrusions are provided only at positions corresponding to the semiconductor chips.

20. The heat sink according to claim 19 , wherein the size of the top surface of the protrusion is smaller than the size of the bottom surface of the semiconductor chip.

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