Semiconductor module and method for manufacturing the same
Patent Information
- Application Number
- JP2024534281
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-06-15
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2043-06-15
AI Technical Summary
Conventional semiconductor modules suffer from the issue of pump-out of thermal grease due to warping of the heat-radiating plate, leading to reduced heat radiation performance and potential electrical discharge.
A semiconductor module design that includes a flexible sheet sandwiched between the heat sink and a frame-shaped case, ensuring a sealed contact area to prevent the pump-out of heat dissipation members and maintain efficient heat dissipation.
The design effectively suppresses the occurrence of pump-out and partial discharge, maintaining high heat dissipation performance even under varying environmental conditions.
Smart Images
Figure 00000009_0000 
Figure 00000009_0001 
Figure 00000009_0002
Abstract
Description
[Technical field]
[0001] The present disclosure relates to a semiconductor module and a method for manufacturing a semiconductor module. [Background technology]
[0002] Semiconductor modules such as semiconductor power modules are used as power conversion devices. In a semiconductor module equipped with a semiconductor device, since a semiconductor chip (IGBT: Insulated Gate Bipolar Transistor, MOSFET: Metal-Oxide-Semiconductor Field Effect Transistor) equipped in the semiconductor device generates heat during operation, a heat sink for cooling the semiconductor device is provided to efficiently dissipate heat. The semiconductor device is equipped with, for example, a metal heat sink, and dissipates heat by contacting the heat sink with the heat sink. If the mounting surface of the heat sink and the heat sink is not flat or has irregularities, the contact area becomes small and the heat dissipation performance is reduced. Therefore, heat dissipation performance is improved by sandwiching heat dissipation grease between the heat sink and the heat sink and deforming it to fit the shape of the mounting surface.
[0003] However, when a semiconductor module is used for a long period of time, the heat sink warps and deforms due to temperature changes, which can cause a pump-out phenomenon in which the heat dissipation grease is gradually discharged. In such a case, if a space is created between the heat sink and the heat sink, discharge may occur. As a countermeasure, it has been proposed to prevent discharge by connecting the heat sink and the heat sink with a conductive material (see, for example, Patent Document 1). [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Patent Publication No. 2022-048552 Summary of the Invention [Problem to be solved by the invention]
[0005] Conventional semiconductor modules do not suppress the pump-out of the heat dissipation grease, which is a heat dissipation material, and therefore have a problem in that the heat dissipation material may pump out, resulting in a decrease in heat dissipation performance.
[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a semiconductor module and a method for manufacturing the semiconductor module that suppresses the occurrence of pump-out of a heat dissipation member. [Means for solving the problem]
[0007] A semiconductor module according to the present disclosure includes a semiconductor device including a heat sink, an insulating layer disposed on an upper surface of the heat sink, circuit electrodes disposed on the upper surface of the insulating layer, a semiconductor chip disposed on the upper surface of the circuit electrodes, and a case formed in a frame shape surrounding the periphery of the heat sink with the lower surface of the heat sink exposed and in contact with the peripheral portion of the upper surface of the insulating layer so as to surround the semiconductor chip, a heat sink fastened to the case, a heat dissipation member sandwiched between the upper surface of the heat sink and the lower surface of the heat sink, and a semiconductor chip disposed on the periphery of the heat dissipation member. Contact The heat sink is formed in a surrounding frame shape and is characterized in that it comprises a flexible sheet sandwiched between the upper surface of the heat sink and the bottom surface of the case, and the heat sink is fastened to the case via the flexible sheet. Effect of the Invention
[0008] A semiconductor module according to the present disclosure includes a semiconductor device including a heat sink, an insulating layer disposed on an upper surface of the heat sink, circuit electrodes disposed on the upper surface of the insulating layer, a semiconductor chip disposed on the upper surface of the circuit electrodes, and a case formed in a frame shape surrounding the periphery of the heat sink with the lower surface of the heat sink exposed and in contact with the peripheral portion of the upper surface of the insulating layer so as to surround the semiconductor chip, a heat sink fastened to the case, a heat dissipation member sandwiched between the upper surface of the heat sink and the lower surface of the heat sink, and a semiconductor chip disposed on the periphery of the heat dissipation member. ContactThe heat sink is formed in a surrounding frame shape and is provided with a flexible sheet sandwiched between the upper surface of the heat sink and the bottom surface of the case, and the heat sink is fastened to the case via the flexible sheet, thereby suppressing the occurrence of pump-out of the heat dissipation member. [Brief description of the drawings]
[0009] [Figure 1] 1 is a schematic cross-sectional view of a semiconductor device in a first embodiment. [Diagram 2] 2 is a bottom view of the semiconductor device in the first embodiment. FIG. [Diagram 3] 1 is a schematic cross-sectional view of a semiconductor module of a first comparative example. [Figure 4] 1 is a schematic cross-sectional view of a semiconductor module according to a first embodiment. [Diagram 5] 2 is a bottom view of the flexible sheet and the semiconductor device in the first embodiment. FIG. [Figure 6] 4 is a bottom view of the semiconductor device after a flexible sheet is provided in the first embodiment. FIG. [Figure 7] 3A to 3C are process diagrams of a method for manufacturing a semiconductor module according to the first embodiment. [Figure 8] 1A to 1C are diagrams showing the semiconductor module according to the first embodiment in the process of being manufactured; [Figure 9] 1A to 1C are diagrams showing the semiconductor module according to the first embodiment in the process of being manufactured; [Figure 10] 13A and 13B are diagrams illustrating a semiconductor module of a second comparative example in the process of being manufactured. [Figure 11] 13 is a diagram showing the semiconductor module according to the first embodiment after a third process. FIG. [Figure 12] FIG. 13 is a diagram showing a semiconductor module according to the second embodiment in the process of being manufactured. [Figure 13] FIG. 11 is a diagram showing the semiconductor module according to the second embodiment after a third process. [Figure 14] FIG. 13 is a diagram showing a semiconductor module according to the third embodiment in the process of being manufactured. [Figure 15]FIG. 13 is a diagram showing a semiconductor module according to the third embodiment in the process of being manufactured. [Figure 16] FIG. 11 is a diagram showing the semiconductor module according to the third embodiment after a third process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] Hereinafter, a semiconductor module and a method for manufacturing the semiconductor module according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in each drawing indicate the same or corresponding parts.
[0011] Embodiment 1 FIG. 1 is a schematic cross-sectional view of a semiconductor device 1 according to a first embodiment. An insulating layer 3 is disposed on the upper surface, which is the front surface, of a metal heat sink 2, a circuit electrode 4 is disposed on the upper surface of the insulating layer 3, and a semiconductor chip 5 is disposed on the upper surface of the circuit electrode 4. The semiconductor chip 5 is connected to a terminal 7 through the circuit electrode 4 and a wire 6. The semiconductor chip 5 is surrounded by a case 8, and the inside of the case 8 is filled with an insulating sealant 9 for insulation. The insulating sealant 9 is filled in a space surrounded by the case 8, the insulating layer 3, the circuit electrode 4, the semiconductor chip 5, and the terminal 7. The case 8 is formed in a frame shape surrounding the periphery of the heat sink 2 with the lower surface, which is the rear surface of the heat sink 2, exposed, and is in contact with the peripheral portion of the upper surface of the insulating layer 3 so as to surround the semiconductor chip 5. FIG. 2 is a bottom view of the semiconductor device 1 according to the first embodiment when viewed from the lower surface, which is the rear surface. The case 8 has through holes 10a for screw fixing at the four corners.
[0012] FIG. 3 is a schematic cross-sectional view of a semiconductor module according to a first comparative example. When the semiconductor device 1 is in operation, heat generated from the semiconductor chip 5 is transferred to the heat sink 2. In order to dissipate heat from the heat sink 2, the case 8 and the heat sink 12 are fastened together by screws 13. When fastening the case 8 and the heat sink 12, if the contact surface between the heat sink 2 and the heat sink 12 is uneven and the contact area is small, the heat dissipation efficiency decreases. Therefore, by sandwiching the heat dissipation member 14 between the upper surface of the heat sink 12 and the lower surface of the heat sink 2, the contact area can be increased and the heat dissipation efficiency can be improved. The heat dissipation member 14 is, for example, heat dissipation grease, for example, silicone mixed with a filler of a material with high thermal conductivity. The heat dissipation member 14 is, for example, a heat dissipation sheet, for example, resin mixed with a filler of high thermal conductivity. However, since the heat dissipation sheet may not be able to follow the warping of the heat sink 2 due to temperature changes, it is preferable to use heat dissipation grease for the heat dissipation member 14.
[0013] Since heat is generated during operation of the semiconductor device 1, the difference in thermal expansion coefficient causes warping of the heat sink 2, and in the semiconductor module of the first comparative example shown in Fig. 3, repeated deformation causes pump-out, in which the heat dissipation grease serving as the heat dissipation member 14 leaks out. When the amount of heat dissipation grease serving as the heat dissipation member 14 between the heat sink 2 and the heat sink 12 decreases, a space is created where the heat dissipation member 14 is no longer present, which causes a decrease in heat dissipation performance.
[0014] In addition, in the semiconductor module of the first comparative example shown in FIG. 3, partial discharge may occur in the gap 11 between the side surface of the heat sink 2 and the case 8 due to an electric field generated between a high-voltage portion such as the terminal 7 and the end of the heat sink 2. For example, even if partial discharge does not occur at the operating voltage in a ground environment, the air pressure decreases in a high-altitude environment (a mountaintop, inside an airplane in flight), making discharge more likely to occur, and the possibility of partial discharge occurring in the semiconductor module of the first comparative example increases. Partial discharge is a factor in insulation deterioration or a noise source, so it is necessary to suppress it. As a method for suppressing discharge in the gap 11 between the side surface of the heat sink 2 and the case 8, there is a method of filling the gap 11 with an insulating material, but this requires a process of filling the insulating material without leaving voids, which increases costs.
[0015] Fig. 4 is a schematic cross-sectional view of the semiconductor module according to the first embodiment. The semiconductor module according to the first embodiment shown in Fig. 4 is different from the semiconductor module according to the first comparative example shown in Fig. 3 in that a flexible sheet 15 is added. The flexible sheet 15 is formed in a frame shape surrounding the periphery of the heat dissipation member 14, and is sandwiched between the upper surface of the heat sink 12 and the bottom surface of the case 8 when the case 8 and the heat sink 12 are fastened together. The flexible sheet 15 may surround the periphery of the heat dissipation member 14 without any gaps. The flexible sheet 15 is made of, for example, silicone rubber and is elastic.
[0016] FIG. 5 is a bottom view showing the flexible sheet 15 and the semiconductor device 1 before the flexible sheet 15 is installed on the semiconductor device 1. The lower view of FIG. 5 is a bottom view of the semiconductor device 1 as viewed from the bottom of the heat sink 2, and the upper view of FIG. 5 is a bottom view of the semiconductor device 1 as viewed from the bottom, which is the back surface of the flexible sheet 15. FIG. 6 is a bottom view of the flexible sheet 15 after it is installed on the semiconductor device 1, showing the semiconductor device 1 with the flexible sheet 15 installed as viewed from the bottom of the heat sink 2. In FIG. 6, the heat sink 12 and the heat dissipation member 14 are not shown. The flexible sheet 15 is formed in a frame shape having a through hole 16 in a portion overlapping with the heat sink 2. The size of the through hole 16 of the flexible sheet 15 is larger than the size of the heat sink 2 and smaller than the size of the outer periphery of the case 8. For example, the inner peripheral edge of the flexible sheet 15 when viewed from the bottom surface of the heat sink 2 is located outside the outer peripheral edge of the heat sink 2 when viewed from the bottom surface of the heat sink 2. The flexible sheet 15 has a through hole 10b at a position corresponding to the through hole 10a of the case 8, and when the flexible sheet 15 is superimposed on the case 8, the through hole 10a and the through hole 10b become one through hole, and the case 8 and the heat sink 12 are fastened via the flexible sheet 15 by the screw 13. In the semiconductor module in which the case 8 and the heat sink 12 are fastened, the heat dissipation member 14 is sandwiched between the upper surface of the heat sink 12 and the lower surface of the heat sink 2 at the position of the through hole 16 of the flexible sheet 15. As a result, the entire lower surface of the heat sink 2 comes into contact with the heat dissipation member 14, and a high heat dissipation effect can be obtained.
[0017] The flexible sheet 15 is deformed when the case 8 and the heat sink 12 are fastened by the screws 13, and the flexible sheet 15 and the case 8 are brought into close contact with each other, and the flexible sheet 15 and the heat sink 12 are brought into close contact with each other. Since the peripheral portion of the upper surface of the insulating layer 3 is in close contact with the case 8, the space surrounded by the heat sink 12, the flexible sheet 15, the case 8, the heat sink 2, and the insulating layer 3 is sealed, and the heat sink 14 is surrounded by the flexible sheet 15 in the sealed space. As a result, even when heat is generated during operation of the semiconductor device 1 and the heat sink 2 is warped, the heat sink 14 does not leak out of the sealed space, and the outflow of the heat sink 14 due to pump-out is suppressed. Furthermore, since the gap 11 is a space sealed from the outside of the semiconductor module, the air pressure in the gap 11 does not decrease even in a low-air pressure environment such as a high-altitude environment, and the occurrence of partial discharge in the gap 11 is suppressed.
[0018] A method for manufacturing a semiconductor module according to the first embodiment will be described. FIG. 7 is a process diagram of the method for manufacturing a semiconductor module according to the first embodiment, and shows a method for manufacturing a semiconductor module from the semiconductor device 1 shown in FIG. 1, the heat dissipation member 14, the flexible sheet 15, and the heat sink 12. In a first step of step S1, the flexible sheet 15 is placed on the upper surface of the heat sink 12, and the process proceeds to a second step of step S2. In a second step of step S2, the heat dissipation member 14 is placed on the upper surface of the heat sink 12 inside the inner periphery of the flexible sheet 15 so that the heat dissipation member 14 is surrounded by the flexible sheet 15, and the process proceeds to a third step of step S3. In a third step of step S3, the heat dissipation member 14 is sandwiched between the heat sink 12 and the heat sink 2, and the case 8 and the heat sink 12 are fastened together via the flexible sheet 15.
[0019] Figs. 8 and 9 are diagrams showing the semiconductor module according to Embodiment 1 during manufacturing. Fig. 8 is a diagram showing the state before the heat sink 2 and the heat dissipation member 14 come into contact before the third step, and Fig. 9 is a diagram showing the state when the heat sink 2 and the heat dissipation member 14 come into contact before the case 8 and the heat sink 12 are fastened. Before the case 8 and the heat sink 12 are fastened, let the difference in the vertical height between the bottom surface of the heat sink 2 and the bottom surface of the case 8 be t1, the vertical thickness of the heat dissipation member 14 be t2, and the vertical thickness of the flexible sheet 15 be t3. When the heat dissipation member 14 is heat dissipation grease, let the thickness of the application of the heat dissipation grease be t2. At this time, as shown in Fig. 9, before the case 8 and the heat sink 12 are fastened by the screw 13, it is made such that t1 + t2 > t3. That is, before the case 8 and the heat sink 12 are fastened, the value obtained by adding the thickness of the heat dissipation member 14 to the difference in height between the bottom surface of the heat sink 2 and the bottom surface of the case 8 is made larger than the thickness of the flexible sheet 15.
[0020] Fig. 10 is a diagram showing the semiconductor module of the second comparative example during manufacturing. As in the semiconductor module of the second comparative example shown in Fig. 10, if t1 + t2 < t3 before the case 8 and the heat sink 12 are fastened, air remains between the heat sink 2 and the heat dissipation member 14. In the semiconductor module of the second comparative example, even if the thickness of the flexible sheet 15 becomes smaller when the case 8 and the heat sink 12 are fastened by the screw 13 in the third step, since the space surrounded by the heat sink 12, the flexible sheet 15, the case 8, the heat sink 2, and the insulating layer 3 is sealed, air does not leak out, and there is a high possibility that air remains between the heat sink 2 and the heat dissipation member 14, which becomes a factor for lowering the heat dissipation performance. Therefore, in the method for manufacturing the semiconductor module according to Embodiment 1, as shown in Fig. 9, before the case 8 and the heat sink 12 are fastened by the screw 13, it is made such that t1 + t2 > t3.
[0021] 11 is a diagram showing the semiconductor module according to the first embodiment after the third step. In the third step, the case 8 and the heat sink 12 are fastened together by the screws 13, so that the thickness of the heat dissipation member 14 is reduced while spreading laterally, the bottom surface of the case 8 and the flexible sheet 15 come into contact with each other, and the thickness of the flexible sheet 15 is then slightly compressed, sealing the space surrounded by the heat sink 12, the flexible sheet 15, the case 8, the heat sink 2, and the insulating layer 3. After the case 8 and the heat sink 12 are fastened together by the screws 13 in the third step, if the thickness of the heat dissipation member 14 in the vertical direction is t21 and the thickness of the flexible sheet 15 in the vertical direction is t31, then t1+t21=t31 as shown in FIG.
[0022] When the case 8 and the heat sink 12 are fastened by the screws 13 in the third step, the heat dissipation member 14 becomes thinner and spreads laterally, and comes into contact with the flexible sheet 15 as shown in FIG. 11. Therefore, when the heat dissipation member 14 is installed on the upper surface of the heat sink 12 inside the frame of the flexible sheet 15 in the second step, it is preferable to provide a space between the heat dissipation member 14 and the flexible sheet 15 as shown in FIG. 8. When the case 8 and the heat sink 12 are fastened by the screws 13 in the third step, the heat dissipation member 14 becomes thinner and spreads laterally, and when the heat dissipation member 14 comes into contact with the flexible sheet 15 and can no longer spread laterally, the screws 13 cannot be tightened any further. If an excessive force is applied to the flexible sheet 15 due to the force tightening the screws 13 being too strong, a creep phenomenon may occur over the long term, and the sealing performance of the space surrounded by the heat sink 12, the flexible sheet 15, the case 8, the heat dissipation plate 2, and the insulating layer 3 may be reduced. However, in the semiconductor module according to embodiment 1, the thickness t31 of flexible sheet 15 shown in FIG. 11 does not fall below t1+t21, so by setting the thickness t3 of flexible sheet 15 before deformation and the thickness t2 of heat dissipation member 14 before deformation based on the thickness t31 of flexible sheet 15 after deformation and the thickness t21 of heat dissipation member 14 after deformation, it is possible to prevent excessive force from being applied to flexible sheet 15 and to suppress the occurrence of the creep phenomenon.
[0023] As described above, the semiconductor module according to the first embodiment includes a semiconductor device 1 including a heat sink 2, an insulating layer 3 arranged on the upper surface of the heat sink 2, a circuit electrode 4 arranged on the upper surface of the insulating layer 3, a semiconductor chip 5 arranged on the upper surface of the circuit electrode 4, and a case 8 formed in a frame shape surrounding the periphery of the heat sink 2 with the lower surface of the heat sink 2 exposed and in contact with the peripheral portion of the upper surface of the insulating layer 3 so as to surround the semiconductor chip 5, a heat sink 12 fastened to the case 8, a heat dissipation member 14 sandwiched between the upper surface of the heat sink 12 and the lower surface of the heat sink 2, and a flexible sheet 15 formed in a frame shape surrounding the periphery of the heat dissipation member 14 and sandwiched between the upper surface of the heat sink 12 and the bottom surface of the case 8, and since the heat sink 12 is fastened to the case 8 via the flexible sheet 15, the occurrence of pump-out of the heat dissipation member 14 is suppressed.
[0024] Embodiment 2 In the semiconductor module according to the first embodiment, the width of the through hole 16 of the flexible sheet 15 is made larger than the width of the heat sink 2, that is, the inner peripheral edge of the flexible sheet 15 when viewed from the bottom surface of the heat sink 2 is located outside the outer peripheral edge of the heat sink 2 when viewed from the bottom surface of the heat sink 2. In this structure, if there is a narrow portion on the bottom surface of the case 8 (for example, a narrow portion on the upper or lower side of the case 8 in FIG. 5 in FIG. 5), the narrow portion on the bottom surface of the case 8 may enter the through hole 16 of the flexible sheet 15 if the positional accuracy when attaching the case 8 to the flexible sheet 15 is low. If the narrow portion on the bottom surface of the case 8 enters the through hole 16 of the flexible sheet 15, the space surrounded by the heat sink 12, the flexible sheet 15, the case 8, the heat sink 2, and the insulating layer 3 in the semiconductor module is not sealed, and the effect of the semiconductor module according to the first embodiment is not obtained. In the semiconductor module according to embodiment 2, the width of through hole 16 in flexible sheet 15 is made smaller than the width of heat sink 2, thereby preventing the narrow portion of the bottom surface of case 8 from entering through hole 16 in flexible sheet 15.
[0025] FIG. 12 is a diagram showing a semiconductor module according to the second embodiment in the middle of manufacture, showing the semiconductor device 1, the heat sink 12, the flexible sheet 15, and the heat dissipation member 14 after the first and second steps and before the third step in FIG. 7. The steps of the method for manufacturing the semiconductor module according to the second embodiment are the same as the steps of the method for manufacturing the semiconductor module according to the first embodiment shown in FIG. 7. In the semiconductor module according to the second embodiment, the width of the through hole 16 in the flexible sheet 15 is smaller than the width of the heat sink 2, and a part of the flexible sheet 15 overlaps with the end of the heat sink 2. For example, the inner peripheral end of the flexible sheet 15 when viewed from the bottom of the heat sink 2 is located inside the outer peripheral end of the heat sink 2 when viewed from the bottom of the heat sink 2. Note that in order to fasten the case 8 and the heat sink 12 via the flexible sheet 15, the outer peripheral end of the flexible sheet 15 when viewed from the bottom of the heat sink 2 is located outside the outer peripheral end of the heat sink 2 when viewed from the bottom of the heat sink 2. A portion of flexible sheet 15 near the inner circumferential edge overlaps with an edge of heat sink 2. This allows case 8 to be easily placed on flexible sheet 15 even when the positional accuracy when attaching case 8 to flexible sheet 15 is low.
[0026] In the semiconductor module according to the second embodiment, if the vertical thickness t2 of the heat dissipation member 14 is smaller than the vertical thickness t3 of the flexible sheet 15 before the case 8 and the heat sink 12 are fastened together, air will remain between the heat sink 2 and the heat dissipation member 14 in the semiconductor module after the third step. Therefore, as shown in Fig. 12, the vertical thickness t2 of the heat dissipation member 14 is made larger than the vertical thickness t3 of the flexible sheet 15 before the case 8 and the heat sink 12 are fastened together by the screws 13. In addition, since the heat dissipation member 14 spreads laterally when the case 8 and the heat sink 12 are fastened together by the screws 13 in the third step, a space is provided between the heat dissipation member 14 and the flexible sheet 15 before the case 8 and the heat sink 12 are fastened together.
[0027] 13 is a diagram showing the semiconductor module according to the second embodiment after the third process. By fastening the case 8 and the heat sink 12 with the screws 13, the vertical thickness of the flexible sheet 15 at the position in contact with the heat sink 2 becomes smaller than the vertical thickness of the flexible sheet 15 at the position not in contact with the heat sink 2. That is, the flexible sheet 15 of the semiconductor module according to the second embodiment has a smaller thickness at a position inside the outer circumferential edge of the heat sink 2 than the thickness at a position outside the outer circumferential edge of the heat sink 2. As a result, the vertical thickness of the flexible sheet 15 at the position in contact with the heat sink 2 becomes smaller than the vertical thickness at the position in contact with the case 8. As a result, in the semiconductor module according to the second embodiment, the volume of the heat dissipation member 14 can be made smaller than that of the semiconductor module according to the first embodiment. Also in the semiconductor module according to embodiment 2, the space surrounded by the heat sink 12, flexible sheet 15, case 8, heat sink 2 and insulating layer 3 is sealed, suppressing the occurrence of pump-out of the heat dissipation member 14 and suppressing the occurrence of partial discharge in the gap 11 even in a low-pressure environment such as a high-altitude environment.
[0028] Embodiment 3 In the semiconductor module according to the second embodiment, the thickness t2 of heat dissipation member 14 is determined in accordance with the thickness t3 of flexible sheet 15. Therefore, when it is desired to reduce the thickness t2 of heat dissipation member 14, it is necessary to reduce the thickness t3 of flexible sheet 15; however, if the thickness t3 of flexible sheet 15 is made too small, it becomes impossible to maintain the airtightness between the bottom surface of case 8 and the upper surface of flexible sheet 15, and between the lower surface of flexible sheet 15 and the upper surface of heat sink 12.
[0029] 14 and 15 are diagrams showing the semiconductor module according to the third embodiment in the middle of manufacture. FIG. 14 is a diagram showing the state before the heat sink 2 and the heat dissipation member 14 come into contact with each other before the third step, and FIG. 15 is a diagram showing the state when the heat sink 2 and the heat dissipation member 14 come into contact with each other before the case 8 and the heat sink 12 are fastened. The steps of the method for manufacturing the semiconductor module according to the third embodiment are the same as the steps of the method for manufacturing the semiconductor module according to the first embodiment shown in FIG. 7. The inner peripheral end of the flexible sheet 15 when viewed from the bottom surface of the heat sink 2 is located inside the outer peripheral end of the heat sink 2 when viewed from the bottom surface of the heat sink 2, and the outer peripheral end of the flexible sheet 15 when viewed from the bottom surface of the heat sink 2 is located outside the outer peripheral end of the heat sink 2 when viewed from the bottom surface of the heat sink 2, as in the semiconductor module according to the second embodiment. In the semiconductor module according to embodiment 3, before the case 8 and the heat sink 12 are fastened together, the vertical thickness of flexible sheet 15 at a position where it overlaps with heat sink 2 when viewed from the underside of heat sink 2 after the case 8 and the heat sink 12 are fastened together is made smaller than the vertical thickness of flexible sheet 15 at a position where it contacts the bottom surface of case 8 after the case 8 and the heat sink 12 are fastened together, and the vertical thickness of heat dissipation member 14 is made larger than the vertical thickness of flexible sheet 15 at a position where it overlaps with heat sink 2 when viewed from the underside of heat sink 2 after the case 8 and the heat sink 12 are fastened together. For example, before the case 8 and the heat sink 12 are fastened together, the vertical thickness of the flexible sheet 15 at the position where it will come into contact with the heat sink 2 after the case 8 and the heat sink 12 are fastened together is made smaller than the vertical thickness of the flexible sheet 15 at the position where it will come into contact with the bottom surface of the case 8 after the case 8 and the heat sink 12 are fastened together, and the vertical thickness of the heat dissipation member 14 is made larger than the vertical thickness of the flexible sheet 15 at the position where it will come into contact with the heat sink 2 after the case 8 and the heat sink 12 are fastened together.Flexible sheet 15 of the semiconductor module according to embodiment 3 has, for example, a stepped cross section, and when the vertical thickness of step portion 151, which is at a position that overlaps with heat sink 2 after case 8 and heat sink 12 are fastened, is t4, then "t2>t4" and "t1+t2>t3" are satisfied before case 8 and heat sink 12 are fastened together.
[0030] 16 is a diagram showing the semiconductor module according to the third embodiment after the third step. As with the flexible sheet 15 of the semiconductor module according to the second embodiment, the flexible sheet 15 of the semiconductor module according to the third embodiment has a smaller thickness in the vertical direction at the position where it contacts the heat sink 2 than at the position where it contacts the case 8. After the case 8 and the heat sink 12 are fastened by the screws 13 in the third step, if the vertical thickness of the heat sink member 14 is t21, the vertical thickness of the flexible sheet 15 at the portion sandwiched between the case 8 and the heat sink 12 is t31, and the vertical thickness of the step portion 151 at the portion sandwiched between the heat sink 2 and the heat sink 12 is t41, then t21=t41, and t1+t21=t31, as shown in FIG. 16. In the semiconductor module according to the third embodiment, the thickness of the heat sink member 14 can be reduced while maintaining the thickness of the flexible sheet 15 required for fastening. That is, the space surrounded by heat sink 12, flexible sheet 15, case 8, heat sink 2, and insulating layer 3 is sealed, and the thickness of heat sink member 14 can be made smaller than that of the semiconductor module according to embodiment 2. Also, for example, by aligning the position of step portion 151 of flexible sheet 15 with the position of the outer circumferential edge of heat sink 2, it is possible to suppress misalignment of the installation in the third step.
[0031] While the present disclosure describes various exemplary embodiments, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are assumed within the scope of the technology of the present disclosure, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment. [Explanation of symbols]
[0032] 1 semiconductor device, 2 heat sink, 3 insulating layer, 4 circuit electrode, 5 semiconductor chip, 6 wire, 7 terminal, 8 case, 9 insulating sealing material, 10a, 10b through hole, 11 gap, 12 heat sink, 13 screw, 14 heat dissipation member, 15 flexible sheet, 16 through hole, 151 step portion.
Claims
1. A heat sink, an insulating layer disposed on the upper surface of the heat sink, a circuit electrode disposed on the upper surface of the insulating layer, a semiconductor chip disposed on the upper surface of the circuit electrode, a semiconductor device including a case formed in a frame shape surrounding the periphery of the heat sink with the lower surface of the heat sink exposed, and contacting the peripheral portion of the upper surface of the insulating layer so as to surround the semiconductor chip, a heat sink fastened to the case, a heat dissipation member sandwiched between the upper surface of the heat sink and the lower surface of the heat sink, a flexible sheet formed in a frame shape surrounding and contacting the periphery of the heat dissipation member, and sandwiched between the upper surface of the heat sink and the bottom surface of the case, The heat sink is fastened to the case via the flexible sheet, and a semiconductor module characterized by this.
2. The semiconductor module according to claim 1, wherein the inner peripheral end of the flexible sheet is located outside the outer peripheral end of the heat sink.
3. The semiconductor module according to claim 1, wherein the inner peripheral end of the flexible sheet is located inside the outer peripheral end of the heat sink.
4. The semiconductor module according to claim 3, wherein the thickness of the flexible sheet at the position where it contacts the heat sink is smaller than the thickness at the position where it contacts the case.
5. A semiconductor module manufacturing method comprising a heat sink, an insulating layer disposed on the upper surface of the heat sink, a circuit electrode disposed on the upper surface of the insulating layer, a semiconductor chip disposed on the upper surface of the circuit electrode, and a case formed in a frame shape surrounding the periphery of the heat sink with the lower surface of the heat sink exposed, and contacting the peripheral portion of the upper surface of the insulating layer so as to surround the semiconductor chip, a heat dissipation member, a flexible sheet formed in a frame shape, and a heat sink, the method including: a first step of installing the flexible sheet on the upper surface of the heat sink; a second step of installing the heat dissipation member on the upper surface of the heat sink so as to be surrounded by the flexible sheet inside the inner periphery of the flexible sheet; a third step of sandwiching the heat dissipation member between the heat sink and the heat sink, and fastening the case and the heat sink via the flexible sheet so that the flexible sheet contacts and surrounds the periphery of the heat dissipation member.
6. A method for manufacturing a semiconductor module in which an inner peripheral end of the flexible sheet is located outside an outer peripheral end of the heat dissipation plate, before the case and the heat sink are fastened, The method for manufacturing a semiconductor module according to claim 5, wherein a value obtained by adding the thickness of the heat dissipation member to a height difference between a bottom surface of the heat dissipation plate and a bottom surface of the case is larger than the thickness of the flexible sheet.
7. A method for manufacturing a semiconductor module in which an inner peripheral end of the flexible sheet is located inside an outer peripheral end of the heat dissipation plate, before the case and the heat sink are fastened, The method for manufacturing a semiconductor module according to claim 5, wherein the thickness of the heat dissipation member is larger than the thickness of the flexible sheet.
8. A method for manufacturing a semiconductor module in which an inner peripheral end of the flexible sheet is located inside an outer peripheral end of the heat dissipation plate, before the case and the heat sink are fastened, The method for manufacturing a semiconductor module according to claim 5, wherein the thickness of the flexible sheet at a position overlapping the heat dissipation plate after the case and the heat sink are fastened is smaller than the thickness of the flexible sheet at a position contacting the bottom surface of the case after the case and the heat sink are fastened, and the thickness of the heat dissipation member is larger than the thickness of the flexible sheet at a position overlapping the heat dissipation plate after the case and the heat sink are fastened.