Power conversion device

Abstract

To suppress pump-out of a heat dissipation member while reducing bending stress on an insulating substrate.SOLUTION: A power conversion device includes a semiconductor module having a heat dissipation surface on at least one surface thereof and including a semiconductor element in a sealing resin, a cooling member having a cooling surface opposed to the heat dissipation surface, and an insulating substrate disposed between the heat dissipation surface and the cooling surface. The sealing resin has a pair of protruding portions that protrude beyond the thickness of the insulating substrate at both ends in the short length direction of the insulating substrate, and have ends in contact with the cooling member directly or via a buffer member. The protruding portions form a holding portion which is a space for holding the insulating substrate between the heat dissipation surface and the cooling surface via a heat dissipation member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] Power conversion devices that convert DC power and AC power are used in various devices, and are required to be small and have high power conversion efficiency. In addition, power conversion devices inevitably generate heat according to the amount of power converted, and measures to dissipate heat are also required. Patent Document 1 discloses a power module that includes a first insulating substrate having a first conductive layer on its surface, a first semiconductor device arranged on the first conductive layer and having a first electrode connected to the first conductive layer, a first signal wiring formed on the surface of the first insulating substrate and connected to a second electrode of the first semiconductor device, a second signal wiring formed on the surface side of the first insulating substrate and connected to a third electrode of the first semiconductor device, and an insulating layer arranged on the first insulating substrate, and the first signal wiring and the second signal wiring are arranged with the insulating layer sandwiched between them. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 043535 Summary of the Invention [Problem to be solved by the invention]

[0004] The invention described in Patent Document 1 leaves room for improvement in dealing with pump-out, in which the heat dissipating member is pushed out to the outside. [Means for solving the problem]

[0005] A power conversion device according to a first aspect of the present invention comprises a semiconductor module having a heat dissipation surface on at least one side and having a semiconductor element embedded in sealing resin, a cooling member having a cooling surface opposite the heat dissipation surface, and an insulating substrate arranged between the heat dissipation surface and the cooling surface, wherein the sealing resin has a pair of convex portions that protrude beyond the thickness of the insulating substrate at both ends in the short direction of the insulating substrate and contact the cooling member at their tips directly or via a buffer member, and the convex portions form a holding portion, which is a space between the heat dissipation surface and the cooling surface that holds the insulating substrate via the heat dissipation member. Effect of the Invention

[0006] According to the present invention, it is possible to reduce bending stress on an insulating substrate and suppress pump-out of a heat dissipation member. [Brief description of the drawings]

[0007] [Figure 1] Cross-sectional view of power conversion device 1 [Diagram 2] Cross-sectional view of Fig. 1 along line II-II [Diagram 3] Cross-sectional view of the power conversion device 1 in a first modified example. [Figure 4] FIG. 13D is a diagram illustrating a step portion 13D. [Diagram 5] Cross-sectional view of the power conversion device 1 in a modified example 2. [Figure 6] FIG. 13 is a diagram showing a shape of a sealing resin 13 in a third modified example. [Figure 7] 11 is a cross-sectional view of the power converter 1 at the position of a heat dissipation surface 12H in a fourth modified example. [Figure 8] 1 is a cross-sectional view of another embodiment of the power converter 1 at the position of the heat dissipation surface 12H. [Figure 9] 1 is a cross-sectional view of the power converter 1 in another embodiment at the position of the heat dissipation surface 12H. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] --Embodiment-- Hereinafter, an embodiment of a power conversion device will be described with reference to Figures 1 and 2. In this embodiment, common XYZ axes are defined to clearly show the correlation between the drawings.

[0009] Fig. 1 is a cross-sectional view of a power conversion device 1. In Fig. 1, the top of the figure is the positive side of the Z axis, the right side of the figure is the X axis, and the depth direction of the figure is the positive side of the Y axis. The power conversion device 1 includes a semiconductor element 11, a conductor 12, a sealing resin 13, and a cooling member 17.

[0010] The semiconductor element 11 is one or more power semiconductor elements that generate heat during operation. The conductor 12 is connected to the semiconductor element 11 and serves as a path for power input to and output from the semiconductor element 11. The conductor 12 also functions as a heat exhaust path for heat generated by the semiconductor element 11. In the following, the end of the conductor 12 on the positive side of the Z axis is referred to as the heat dissipation surface 12H. The entire semiconductor element 11 and part of the conductor 12 are sealed with sealing resin 13. The heat dissipation surface 12H, which is the end of the conductor 12 on the positive side of the Z axis, is exposed from the sealing resin 13, and the heat generated by the semiconductor element 11 is released from the heat dissipation surface 12H to the outside of the sealing resin 13.

[0011] The sealing resin 13 has a protrusion 13P that protrudes toward the positive side of the Z axis. The protrusions 13P are a pair, i.e., two rows of protrusions, and form a groove whose cross section in the XZ plane is U-shaped. The space formed inside this U-shaped groove is called a holding portion 14. A heat dissipation member 15 and an insulating substrate 16 are disposed in the holding portion 14. Although the reference numeral for the holding portion 14 is not shown in FIG. 1, the combined area of ​​the heat dissipation member 15 and the insulating substrate 16 is the area of ​​the holding portion 14.

[0012] The heat dissipation member 15 is a thermal interface material, such as thermally conductive grease or gap filler. The insulating substrate 16 is a ceramic white board or a ceramic substrate having circuit wiring. The insulating substrate 16 spreads in the XY plane and has a flat plate shape with a thickness in the Z-axis direction. The insulating substrate 16 has a short side direction in the X-axis direction and a long side direction in the Y-axis direction. The gaps on the positive and negative sides of the Z-axis of the insulating substrate 16 placed in the holding portion 14 are filled with the heat dissipation member 15. Therefore, the heat of the semiconductor element 11 and the heat of the insulating substrate 16 can be discharged to the cooling member 17.

[0013] A cooling member 17 is disposed on the upper part of the sealing resin 13, and cools the semiconductor element 11 and the insulating substrate 16. The cooling member 17 has a flow path through which a refrigerant flows, and the cooling member 17 is cooled by the refrigerant flowing through the flow path by a configuration not shown. The end surface of the cooling member 17 on the negative side of the Z axis is called a cooling surface 17S. The insulating substrate 16 is disposed between the heat dissipation surface 12H and the cooling surface 17S. The heat dissipation member 15 disposed on the holding part 14 contacts the cooling surface 17S directly, and the convex part 13P contacts the cooling surface 17S via the buffer member 18. When the sealing resin 13 was formed, the mold was in contact with the part corresponding to the convex part 13P. In other words, the convex part 13P is a mold release surface, and therefore has high dimensional accuracy. The buffer member 18 may be the same material as the heat dissipation member 15, or may be a different material.

[0014] An enlarged view of the vicinity of insulating substrate 16 is shown at the bottom of Fig. 1. The side surface of protrusion 13P in this embodiment is linear, and the width of holding portion 14 in the X-axis direction narrows toward the negative side of the Z-axis. Insulating substrate 16 contacts protrusion 13P at a position in the Z-axis direction where the widths in the X-axis direction match. In the following, semiconductor element 11, conductor 12, and sealing resin 13 are collectively referred to as semiconductor module 30.

[0015] Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 2, the power conversion device 1 has many semiconductor elements 11 in the Y-axis direction, and the multiple semiconductor elements 11 are cooled by one cooling member 17. Furthermore, even if the Z-axis coordinate positions of the heat dissipation surfaces 12H in the respective semiconductor modules 30 are different, the insulating substrate 16 can be held horizontally.

[0016] According to the above-described embodiment, the following advantageous effects can be obtained. (1) The power converter 1 includes a semiconductor module 30 having a heat dissipation surface 12H on at least one side thereof and a semiconductor element 11 built in a sealing resin 13, a cooling member 17 having a cooling surface 17S facing the heat dissipation surface 12H, and an insulating substrate 16 disposed between the heat dissipation surface 12H and the cooling surface 17S. The sealing resin 13 has a pair of protruding portions 13P that protrude beyond the thickness of the insulating substrate 16 at both ends of the short side direction of the insulating substrate 16, i.e., the X-axis, and contacts the cooling member 17 at its tip via a buffer member 18. The protruding portions 13P form a holding portion 14, which is a space that holds the insulating substrate 16 via the heat dissipation member 15, between the heat dissipation surface 12H and the cooling surface 17S. Therefore, the cooling member 17 is mainly supported by the protruding portions 13P, so that the force applied to the insulating substrate 16 is reduced, and furthermore, the pair of protruding portions 13P can suppress pump-out of the heat dissipation member 15.

[0017] (2) A plurality of semiconductor modules 30 are arranged in the longitudinal direction of insulating substrate 16. Cooling member 17 is arranged along the longitudinal direction of insulating substrate 16. Therefore, a plurality of semiconductor modules 30 can be cooled by one cooling member 17, which reduces costs and prevents insulating substrate 16 from tilting.

[0018] (Variation 1) FIG. 3 is a cross-sectional view of the power converter 1 in the first modification. The difference from the embodiment is that the protrusion 13P has a step 13D. The step 13D is a plane extending in the XY direction substantially parallel to the heat dissipation surface 12H and the cooling surface 17S. An insulating substrate 16 is disposed on the step 13D. The step 13D has high dimensional accuracy because it is formed as a mold release surface. In this modification, the region on the most negative side of the Z axis in the holder 14 is called the holder bottom 14B.

[0019] Fig. 4 is a diagram for explaining the step portion 13D. Fig. 4 illustrates an XY plane, with the positive side of the Z axis facing the viewer. The lattice-like hatching in the center of Fig. 4 indicates the holding bottom portion 14B, the diagonal lattice-like hatching indicates the step portion 13D, and the dashed line indicates the insulating substrate 16. However, the insulating substrate 16 may coincide with the outer periphery of the step portion 13D.

[0020] According to the first modification, the following advantageous effects can be obtained. (3) The protruding portion 13P has a step portion 13D that supports the insulating substrate 16. Therefore, the insulating substrate 16 can be easily positioned and the insulating substrate 16 can be stably supported horizontally.

[0021] (Variation 2) 5 is a cross-sectional view of the power conversion device 1 in the modified example 2. The difference from the modified example 1 is that the insulating substrate 16 and the step portion 13D are fixed by an adhesive member 20. In this modified example, the insulating substrate 16 can be reliably fixed by the adhesive member 20. In addition, since the adhesive member 20 has insulating properties, it is possible to prevent creeping discharge from the heat dissipation surface 12H to the cooling member 17 via the protrusion 13P.

[0022] According to the second modification, the following advantageous effects can be obtained. (4) The insulating substrate 16 is fixed to the stepped portion 13D via the adhesive member 20. This prevents the insulating substrate 16 from shifting in position, and also prevents creeping discharge.

[0023] (Variation 3) In the embodiment described above, the shape of the sealing resin 13 at both ends in the Y-axis direction is not specified. However, as described below, the sealing resin 13 may be configured to surround the holding portion 14 from all sides.

[0024] FIG. 6 is a diagram showing the shape of the sealing resin 13 in the third modified example. FIG. 6 shows the XY plane, with the positive side of the Z axis facing the viewer. The cooling member 17 and the buffer member 18 are not shown in FIG. 6. The position of the convex portion 13P is the same as in the embodiment. The sealing resin 13 in this modified example has a second convex portion 13Q. The holding portion 14 is sandwiched between the convex portions 13P at both ends in the X-axis direction, and between the second convex portions 13Q at both ends in the Y-axis direction. That is, the holding portion 14 is surrounded on all four sides by the sealing resin 13, so that the heat dissipation member 15 is even less likely to be pumped out than in the embodiment.

[0025] According to the third modification, the following advantageous effects can be obtained. (5) Protrusions 13P are provided along the longitudinal direction of insulating substrate 16. Sealing resin 13 has a pair of second protrusions 13Q that protrude beyond the thickness of insulating substrate 16 at both ends of insulating substrate 16 in the lateral direction along the lateral direction of insulating substrate 16 and contact cooling member 17 at their tips via buffer member 18. Therefore, holding portion 14 is surrounded on all four sides by sealing resin 13, making heat dissipation member 15 even less likely to pump out than in the embodiment.

[0026] (Variation 4) In the above-described embodiment, the shape of the convex portion 13P at the height of the heat dissipation surface 12H is not specified. However, a space may be provided between the heat dissipation surface 12H and the convex portion 13P. This space may be formed by forming a space formed by the convex portion 13P in an XY plane where the Z-axis position is the heat dissipation surface 12H in a similar shape to, but slightly larger than, the heat dissipation surface 12H. Furthermore, as described below, this space may have an uneven shape.

[0027] FIG. 7 is a cross-sectional view of the power converter 1 at the position of the heat dissipation surface 12H in the fourth modification. The outer periphery of FIG. 7 is the convex portion 13P, and the central rectangle is the heat dissipation surface 12H. The area indicated by hatching with dots between the heat dissipation surface 12H and the convex portion 13P is the evacuation space 25. As shown in the lower part of FIG. 7, the evacuation space 25 is formed by moving a part of the linear convex portion 13P in the opposite direction to the heat dissipation surface 12H. Note that the movement of the part of the convex portion 13P is not limited to a parallel movement, and may be an oblique movement as shown in FIG. 8.

[0028] Fig. 9 is a cross-sectional view of power conversion device 1 in yet another embodiment at the position of heat dissipation surface 12H. The difference from Fig. 7 is that sealing resin 13 includes second protrusion 13Q as in modification 3, and part of second protrusion 13Q, which is linear, moves in the opposite direction to heat dissipation surface 12H, thereby further expanding evacuation space 25.

[0029] According to the fourth modification, the following advantageous effects can be obtained. (6) The projection 13P has a space between it and the heat dissipation surface 12H, which is the evacuation space 25. Therefore, the excess heat dissipation material 15 applied to the heat dissipation surface 12H can be evacuated to the evacuation space 25, thereby improving productivity and reliability.

[0030] (7) The escape space 25 is formed by moving a part of the linear protrusion 13P in the opposite direction to the heat dissipation surface 12H. Therefore, the escape space 25 for evacuating the heat dissipation member 15 can be formed as a narrow area.

[0031] (Variation 5) In the above-described embodiment, the protrusions 13P come into contact with the cooling member 17 via the buffer members 18. However, the protrusions 13P may come into contact with the cooling member 17 directly, that is, without the buffer members 18 therebetween.

[0032] (Variation 6) In the above-described embodiment, the power conversion device 1 includes a plurality of semiconductor modules 30. However, the power conversion device 1 may include only one semiconductor module 30.

[0033] The above-mentioned embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other aspects that are conceivable within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention. [Explanation of symbols]

[0034] 1: Power conversion device 11: Semiconductor elements 12: Conductor 12H: Heat dissipation surface 13: Sealing resin 13D: Step 13P: Convex 13Q: Second protrusion 14: Holding part 14B: Retention bottom 15: Heat dissipation material 16: Insulating substrate 17: Cooling material 17S: Cooling surface 18: Cushioning material 20: Adhesive material 25: Evacuation space 30: Semiconductor module

Claims

1. a semiconductor module having a heat dissipation surface on at least one side thereof and having a semiconductor element embedded in a sealing resin; a cooling member having a cooling surface facing the heat dissipation surface; an insulating substrate disposed between the heat dissipation surface and the cooling surface; the sealing resin has a pair of protruding portions that protrude beyond a thickness of the insulating substrate at both ends in a short side direction of the insulating substrate and that contact the cooling member directly or via a buffer member at their tips; The convex portion forms a holding portion, which is a space between the heat dissipation surface and the cooling surface and holds the insulating substrate via a heat dissipation member, in a power conversion device.

2. 2. The power conversion device according to claim 1, The protrusion has a step portion that supports the insulating substrate.

3. 3. The power conversion device according to claim 2, The insulating substrate is fixed to the step portion via an adhesive member.

4. 2. The power conversion device according to claim 1, The semiconductor modules are arranged in a plurality of positions in a longitudinal direction of the insulating substrate, The cooling member is disposed along the longitudinal direction of the insulating substrate.

5. The power conversion device according to claim 4, The protrusion is provided along the longitudinal direction of the insulating substrate, the sealing resin further has a pair of second convex portions that protrude beyond the thickness of the insulating substrate at both ends of the insulating substrate in the short direction of the insulating substrate and that contact the cooling member at their tips directly or via the buffer member.

6. 2. The power conversion device according to claim 1, The convex portion has a retreat space between the heat dissipation surface and the convex portion.

7. 7. The power conversion device according to claim 6, The power conversion device, wherein the evacuation space is formed by moving a part of the linear protrusion in a direction opposite to the heat dissipation surface.

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