Power Module

Abstract

The present invention relates to a power module. The power module comprises: a power semiconductor element, a cooler for cooling the power semiconductor element, a housing fixed to the cooler and accommodating the power semiconductor element, and a sealing material for sealing the power semiconductor element, wherein the housing is provided with: a bonding groove formed on a surface bonded to the cooler and filled with the sealing material, and an inflow hole connected to the bonding groove and into which the sealing material flows.

Description

Technical Field

[0001] The present invention relates to a power module.

[0002] This application claims the benefit of priority based on Japanese Patent Application No. 2019-064549 filed in Japan on March 28, 2019, the contents of which are hereby incorporated by reference. Background Art

[0003] For example, Japanese Patent Application Laid-Open No. 2014-103846 discloses a power semiconductor device in which a housing (casing) is bonded to a heat sink (cooler).

[0004] In Japanese Patent Application Laid-Open No. 2014-103846, protrusions are provided on a bonding surface of a housing to be bonded to a heat sink, and an adhesive is filled in a gap between the heat sink and the housing caused by the protrusions, thereby bonding the heat sink and the housing.

[0005] However, in a power module, a gel-like sealing material is sometimes used to cover the power semiconductor element for the purpose of electrical insulation of the power semiconductor element. In this case, it is conceivable to bond the cooler to the housing as described above. The power semiconductor element reaches a high temperature when power is supplied. Therefore, when air remains in the gap (bonding groove) between the cooler and the housing, the heat of the power semiconductor element is transferred to the sealing material, the air expands due to the heat, and bubbles are generated around the mounting surface in the housing, and it may be impossible to achieve electrical insulation of the power semiconductor element. Summary of the invention

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to prevent bubbles from remaining in a sealing material filled in a case and to achieve electrical insulation of a power semiconductor element.

[0007] Solutions to Solve Problems

[0008] In order to achieve the above-mentioned purpose, in the present invention, as a first scheme, the following structure is adopted: a power module, comprising: a power semiconductor element, a cooler for cooling the power semiconductor element, a shell fixed to the cooler and accommodating the power semiconductor element, and a sealing material for sealing the power semiconductor element, wherein the shell is formed with: a bonding groove formed on a surface bonded to the cooler and filled with the sealing material, and an inflow hole connected to the bonding groove and for the sealing material to flow in.

[0009] As a second aspect, the following structure is adopted: in the above-mentioned first aspect, the inflow hole is an identification hole provided so as to penetrate the housing and used for wire bonding of the power semiconductor element.

[0010] As a third solution, the following structure is adopted: in the above-mentioned first or second solution, an air hole connected to the bonding groove is further formed in the housing.

[0011] As a fourth means, the following structure is adopted: in the third means, the air hole is provided to penetrate the housing and one opening end is exposed from the sealing material.

[0012] As a fifth means, in the third or fourth means, a configuration is adopted in which the opening end of the air hole on the side facing the bonding groove is enlarged in diameter.

[0013] Effects of the Invention

[0014] According to the above aspects of the present invention, the sealing material is filled into the bonding groove from the inlet hole connected to the bonding groove. Therefore, by eliminating the air remaining in the housing, bubbles are not generated at high temperatures of the power semiconductor element, thereby achieving electrical insulation of the power semiconductor element. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic cross-sectional view of a power module according to an embodiment of the present invention.

[0016] Figure 2 FIG. 1 is a schematic diagram showing the arrangement of bonding grooves, identification holes, and air holes in a case included in the power module of the present embodiment.

[0017] Figure 3A is a diagram showing this embodiment, Figure 2 AA section view.

[0018] Figure 3B is a diagram showing this embodiment, Figure 2 BB cross-sectional view.

[0019] Description of Reference Numerals

[0020] 1...Power module

[0021] 2……Housing

[0022] 2a…Identify the hole

[0023] 2b... Air holes

[0024] 2c... Adhesive groove

[0025] 3……Power semiconductor components

[0026] 5. Cooler

[0027] 6. Sealing materials

[0028] S... Adhesive DETAILED DESCRIPTION

[0029] Hereinafter, one embodiment of a power module according to the present invention will be described with reference to the drawings.

[0030] The power module 1 of this embodiment includes a power semiconductor element 3 for controlling the energization of a motor (load). Figure 1 As shown, such a power module 1 includes a case 2, a power semiconductor element 3, an electrode 4, a cooler 5, and a sealing material 6. Although not shown, the power module 1 includes an electrode connection terminal and a signal terminal.

[0031] The housing 2 is a rectangular resin case that surrounds the power semiconductor element 3 and the electrode 4 and forms a mounting surface on the cooler 5. In addition, the cooler 5 is provided on the lower surface of the housing 2. Figure 2 , Figure 3A as well as Figure 3B As shown, the housing 2 is formed with an identification hole 2a, an air hole 2b and an adhesive groove 2c. In addition, a signal terminal (not shown) is fixed to the housing 2.

[0032] like Figure 3A As shown, the identification hole 2a is a through hole formed in the housing 2 toward the surface in contact with the cooler 5, and is used as a positioning hole for the wire bonding device when the power semiconductor element 3 is connected to the signal terminal by wire bonding. The identification hole 2a is formed on the bonding groove 2c and penetrates the formation surface formed with the bonding groove 2c and the surface facing the above-mentioned formation surface.

[0033] like Figure 3B As shown, the air hole 2b is formed on the bonding groove 2c and is a through hole that penetrates the forming surface and the surface opposite to the forming surface, similarly to the identification hole 2a. In addition, the opening end side of the air hole 2b on the surface opposite to the forming surface is enlarged to form a structure that allows residual air to be easily discharged. It should be noted that the forming surface is formed with a bonding surface in the central part except near the peripheral edge, and an adhesive is provided on the above-mentioned bonding surface to be bonded to the cooler 5. In addition, the opening position of the air hole 2b on the surface opposite to the forming surface is formed at a position higher in the vertical direction than the identification hole 2a when the sealing material 6 is filled. As a result, when the sealing material 6 is formed on the air hole 2b, the opening position on the surface opposite to the forming surface becomes exposed to the outside.

[0034] The bonding groove 2c is formed on the surface in contact with the cooler 5. Figure 2 As shown in FIG. 2 , the groove is formed by bending in one direction within the range including the identification hole 2a and the air hole 2b. A part of the remaining adhesive S flows into the adhesive groove 2c, and the sealing material 6 flows into the adhesive groove 2c. In addition, in the adhesive groove 2c, as shown in FIG. Figure 3A as well as Figure 3BAs shown, the connection portion connected to the identification hole 2a and the air hole 2b is tapered. By tapering the bonding groove 2c, it is easy to balance the filling space of the sealing material 6 and the discharge of the residual air. It should be noted that the bonding groove 2c is formed to surround the mounting surface of the power semiconductor element 3.

[0035] The power module 1 is a power conversion circuit including a power semiconductor element 3. Such a power module 1 is electrically connected to a signal terminal (not shown) provided with the power semiconductor element 3 on the outer edge of the housing 2 by wire bonding (not shown). The power module 1 is connected to a higher-level control device such as a motor ECU, and controls a step-up / step-down converter, an inverter, etc. mounted on the vehicle based on a control command input from the higher-level control device.

[0036] The electrode 4 is fixedly mounted in the housing 2 in a state of being electrically connected to the power semiconductor element 3 by solder or the like. The electrode 4 is, for example, a DCB (Direct Copper Bonding) substrate composed of a ceramic layer and a copper layer. The battery (not shown) is connected to the motor via a lead frame, a bus bar, etc. (not shown).

[0037] The cooler 5 is formed in a flat container shape having a refrigerant inlet and a refrigerant outlet, and the refrigerant flows inside. The cooler 5 is fixed in a state of contact with the electrode 4 and the housing 2 on one surface. The cooler 5 transfers the heat generated in the power semiconductor element 3 and the like to the refrigerant, thereby cooling the power semiconductor element 3 and the like.

[0038] The sealing material 6 is a semi-transparent silicone soft layer (gel layer) provided so as to cover a part of the case 2 and the power semiconductor element 3 mounted in the case 2. The sealing material 6 is filled from the identification hole 2a into the bonding groove 2c.

[0039] In the power module 1 of the present embodiment, after the power semiconductor element 3 and the electrode 4 are mounted in the housing 2, the sealing material 6 is filled from the identification hole 2a. The sealing material 6 flowing from the identification hole 2a flows into the air hole 2b via the adhesive groove 2c. The sealing material 6 is cured in a state where the opening end on the surface opposite to the formation surface of the air hole 2b is exposed.

[0040] According to the power module 1 of this embodiment, the sealing material 6 is filled from the identification hole 2a to the bonding groove 2c. Thus, the gap between the housing 2 and the cooler 5 can be filled with the sealing material 6, and the air remaining in the housing 2 can be eliminated to prevent the generation of bubbles.

[0041] According to the power module 1 of this embodiment, the air hole 2b connected to the adhesive groove 2c is provided. Thus, the power module 1 can discharge the bubbles remaining in the sealing material 6 flowing into the adhesive groove 2c from the air hole 2b to the outside. Therefore, bubbles can be prevented from remaining in the adhesive groove 2c when the sealing material 6 is filled.

[0042] In addition, according to the power module 1 of the present embodiment, the open end of the air hole 2b on the surface opposite to the formation surface is exposed from the sealing material 6. That is, when the sealing material 6 is filled, the sealing material 6 does not flow in from the air hole 2b, but flows in from the identification hole 2a. Therefore, bubbles are easily discharged from the air hole 2b.

[0043] Furthermore, according to the power module 1 of the present embodiment, the diameter of the opening end side of the air hole 2b on the surface facing the formation surface is enlarged, thereby facilitating the discharge of bubbles from the air hole 2b.

[0044] In the power module 1 of the present embodiment, the connection portion of the adhesive groove 2c with the identification hole 2a and the air hole 2b is tapered, thereby reducing the resistance of the sealing material 6 when it flows from the identification hole 2a into the adhesive groove 2c, making it easier for the sealing material 6 to flow from the identification hole 2a.

[0045] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. The shapes and combinations of the various structural components shown in the above embodiments are examples, and various changes can be made based on design requirements, etc. without departing from the scope of the present invention.

[0046] In the above embodiment, the air hole 2b is formed in addition to the identification hole 2a, but the present invention is not limited to this structure. For example, the identification hole 2a may be connected to the bonding groove 2c. In this case, the bubbles remaining in the bonding groove 2c are discharged from the identification hole 2a to the outside.

[0047] In addition, in the present embodiment, the sealing material 6 is filled from the identification hole 2a to the bonding groove 2c, but the present invention is not limited to this structure. For example, it is also possible to form a through hole (inflow hole) connected to the bonding groove 2c in addition to the identification hole 2a, so that the sealing material 6 flows into the bonding groove 2c.

[0048] In the above embodiment, although not shown for simplicity, a plurality of identification holes 2a are formed in the housing 2. Only a part of the plurality of identification holes 2a may be connected to the adhesive groove 2c.

[0049] Industrial Applicability

[0050] According to the above aspect of the present invention, the sealing material is filled into the bonding groove from the inlet hole connected to the bonding groove. Therefore, by eliminating the air remaining in the housing, bubbles are not generated at high temperatures of the power semiconductor element, thereby achieving electrical insulation of the power semiconductor element.

Claims

1. A power module, characterized in that: have: Power semiconductor components; A cooler for cooling the power semiconductor element; A housing fixed to the cooler and accommodating the power semiconductor element; as well as a sealing material for sealing the power semiconductor element, The housing is provided with: a bonding groove formed on a surface bonded to the cooler and filled with the sealing material, and an inflow hole connected to the bonding groove and into which the sealing material flows. The shell further includes an air hole connected to the bonding groove, the air hole being arranged to penetrate the shell and having one opening end exposed from the sealing material, and the opening position of the air hole on the surface of the shell opposite to the surface bonded to the cooler is higher in the vertical direction than the opening position of the inlet hole. The bonding groove is tapered toward a portion connected to the air hole and tapered toward a portion connected to the inflow hole.

2. The power module according to claim 1, characterized in that: The inflow hole is an identification hole provided so as to penetrate the housing and used for wire bonding of the power semiconductor element.

3. The power module according to claim 1, characterized in that: The opening end of the air hole on the side facing the bonding groove is enlarged in diameter.

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