JP2004296976A - Mounting method of semiconductor power module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting method of a semiconductor power module by which the semiconductor power module of a noninsulation type is easily mounted to a heat sink. <P>SOLUTION: An insulating sheet 21 is first bonded to an upper face of the heat sink 13, then a silicon-based adhesive agent 12 of thermal conductivity and an insulation property is applied to an inner peripheral face surrounded by the insulating sheet 21. The power module 11 is put on the adhesive agent 12 and is heated in an atmosphere of about 140°C to cure the adhesive agent 12, by which the power module 11 and the heat sink 13 are fixed by the adhesive agent 12 with these components kept at a certain interval. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for attaching a semiconductor power module to a heat sink.
[0002]
[Prior art]
As a method of fixing a non-insulated semiconductor power module (hereinafter, referred to as a power module) to a heat sink, a mounting method as shown in FIG. 4 has been conventionally used.
[0003]
On the left and right sides of the case of the power module 41 shown in FIG. 4, step portions 41a having holes for attaching screws 42 are provided.
When fixing the power module 41 to the heat sink 43, the power module 41 is fixed to the heat sink 43 using screws 42 with an insulating sheet having good thermal conductivity interposed between the upper surface of the heat sink 43 and the bottom surface of the power module 41.
[0004]
This mounting method requires an operation of fixing the power module 41 to the heat sink 43 with the screws 42 and a step 41a for screwing the power module 41 to the power module 41 side. However, there was a problem that the size became large.
[0005]
Japanese Patent Application Laid-Open No. 2002-325467 (Patent Document 1) discloses a power supply that eliminates the need to apply an insulating sheet and silicon grease, and ensures insulation between external electrode terminals of a power module and cooling fins (heat sinks). A mounting structure for a module is disclosed.
[0006]
In the invention described in Patent Document 1, a plurality of power modules are surrounded by an outer wall, a gap is provided between a cooling fin and a mounting surface of the power module, and silicon gel is filled in the outer wall, so that an external electrode of the power module is provided. The insulation distance between the terminal and the cooling fin is ensured.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-325467 (FIGS. 1 and 2; summary solution, paragraph 0018)
[0008]
[Patent Document 2]
JP 2003-23280 A (FIG. 6)
[0009]
[Problems to be solved by the invention]
However, the invention described in Patent Document 1 relates to an insulation type power module in which a semiconductor switching element built in the power module is insulated from a mounting surface of the power module.
[0010]
In the invention described in Patent Document 1, it is necessary to provide a gap between the mounting surface of the power module and the cooling fins. This is caused by a slightly protruding structure (paragraph 0011 of Patent Document 1). That is, this mounting method cannot be applied unless the power module is an insulated power module in which a part of the mounting surface of the power module is insulated.
[0011]
An object of the present invention is to simplify the work of attaching a non-insulated semiconductor power module to a heat sink.
[0012]
[Means for Solving the Problems]
A method for mounting a semiconductor power module according to the present invention includes the steps of: applying a heat conductive and insulating adhesive to an upper surface of the heat sink while placing a member having a predetermined thickness on the upper surface of the heat sink; A semiconductor power module is placed on the heat sink, and the adhesive is cured to fix the semiconductor power module to the heat sink while maintaining a predetermined interval.
[0013]
According to the present invention, the semiconductor power module can be attached to the heat sink without using screws, so that the number of assembling operations can be reduced. Further, since it is not necessary to provide a portion for screwing the semiconductor power module, the semiconductor power module can be downsized.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a mounting structure of a power module according to an embodiment of the present invention.
The power module 11 incorporates one or a plurality of semiconductor elements, and is bonded on a finned heat sink 13 with a silicon-based adhesive 12 having thermal conductivity and insulating properties. The thickness of the silicon-based adhesive 12 is set such that an insulation distance with respect to a voltage applied to the drain (or collector) electrode of the power module 11 can be secured.
[0015]
Next, an operation procedure for fixing the power module 11 to the heat sink 13 using the adhesive 12 will be described.
FIG. 2 is an explanatory diagram of the first embodiment of the present invention in which the adhesive 12 is applied using the insulating sheet 21.
[0016]
In the first embodiment, an insulating sheet 21 as shown in FIG. 2B is used as a member for securing the thickness of the silicon-based adhesive 12.
The insulating sheet 21 has a thickness (for example, t = 0.1 to 0.3 mm) enough to secure an insulating distance with respect to a voltage applied to the power module 11, and an adhesive is applied to one or both surfaces. Have been.
[0017]
First, the insulating sheet 21 is attached to the upper surface of the heat sink 13. Next, a silicon adhesive 12 having thermal conductivity and insulating properties is applied to the inner peripheral surface surrounded by the insulating sheet 21.
As shown in FIG. 2 (B), the insulating sheet 21 has a mouth-like shape with a size corresponding to the external dimensions of the power module 11, so that the insulating sheet 21 has an area slightly inside the external dimensions of the power module 11. Can be applied with an adhesive 12.
[0018]
Next, the power module 11 is placed on the adhesive 12 and is heated in an atmosphere of about 140 degrees to cure the adhesive 12.
FIG. 2A is a side view showing a state in which an adhesive 12 is applied to the inner peripheral portion of the insulating sheet 21 and the power module 11 is placed thereon and bonded.
[0019]
According to the mounting method of the first embodiment, the weight of the power module 11 (by using a weight jig separately) is applied by applying the silicon-based adhesive 12 to the inner peripheral portion of the insulating sheet 21. The thickness of the adhesive in the process of compressing the adhesive 21 and curing the adhesive 21, that is, the heat radiation surface of the power module 11 (the lower surface of the power module 11 in FIG. 2A) and the upper surface of the heat sink 13 Can be prevented from becoming smaller than the desired insulation distance. In addition, since the power module can be fixed to the heat sink 13 by the adhesive 12, the screwing operation is not required. Further, since it is not necessary to provide a portion for fixing the power module 11 with screws, the external dimensions can be reduced.
[0020]
Next, FIG. 3 is an explanatory view of a mounting method according to the second embodiment in which a silicon-based adhesive 12 is applied using a spacer.
In the second embodiment, four spacers 31 as shown in FIG. 3B are used as members for securing the thickness of the adhesive 12.
[0021]
The spacer 31 has a thickness (for example, t = 0.1 to 0.3 mm) that can ensure insulation between the power module 11 and the heat sink 13.
First, the spacers 31 are placed near the four corners of the heat sink 13 where the power module 11 is to be arranged.
[0022]
Next, a silicon-based adhesive 12 is applied to a region surrounded by the four spacers 31.
Next, the power module 11 is placed on the adhesive 12 and heated in an atmosphere of about 140 degrees to cure the adhesive 12.
[0023]
According to the mounting method of the second embodiment, the adhesive 12 is cured while the spacer 31 is sandwiched between the power module 11 and the heat sink 13, so that the weight of the adhesive 21 Is compressed and the thickness of the adhesive becomes thinner in the process of curing the adhesive 21, and the distance between the heat radiation surface of the power module 11 (the lower surface of the power module 11 in FIG. 2A) and the upper surface of the heat sink 13 Can be prevented from becoming smaller than a desired insulation distance. As long as the spacer 31 can be removed, a non-insulating material may be used.
[0024]
The present invention is not limited to the insulating sheet 21 and the spacer 31 described above, but includes a jig capable of maintaining a constant distance between the power module 11 and the heat sink 13 until the adhesive 12 is applied and the adhesive is cured. Alternatively, the jig may be removed after the bonding operation is performed and the bonding is cured.
[0025]
【The invention's effect】
According to the present invention, the semiconductor power module can be attached to the heat sink without using screws, so that the assembling operation is simplified. Further, since it is not necessary to provide a portion for screwing the semiconductor power module, the semiconductor power module can be downsized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a mounting structure of a power module according to an embodiment.
FIG. 2 is an explanatory diagram of a method of attaching the power module according to the first embodiment.
FIG. 3 is an explanatory diagram of a method of attaching a power module according to a second embodiment.
FIG. 4 is a diagram showing a conventional power module mounting structure.
[Explanation of symbols]
11 Power module 12 Adhesive 13 Heat sink 21 Insulating sheet 31 Spacer

Claims (1)

In a state where a member having a predetermined thickness is placed on the upper surface of the heat sink, an adhesive having thermal conductivity and insulation is applied to the upper surface of the heat sink and an inner peripheral surface surrounded by the member,
A method for mounting a semiconductor power module, comprising: mounting a semiconductor power module on the adhesive, curing the adhesive, and fixing the semiconductor power module to the heat sink while maintaining a predetermined interval.

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