JP2007096191A - Semiconductor device, and the same with radiating mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device in which excess heat conductive grease is extruded efficiently from between a base board and a radiating fin to reduce the thickness of a heat conductive grease film to offer improved heat radiation efficiency. <P>SOLUTION: The semiconductor device connected to the radiating fin via the heat conductive grease includes the base board having a front surface and a back surface, an insulating board placed on the front surface of the base board, and a semiconductor element placed on the insulating board. Recessions are formed on the back surface of the base board, where part of the heat conductive grease is extruded into the recessions when the semiconductor device is connected to the radiating fin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power semiconductor device and a semiconductor device with a heat dissipation mechanism including a heat dissipation fin.

In a power semiconductor device, a semiconductor element such as an IGBT is attached on an insulating substrate having a metal wiring pattern on the front and back surfaces. The insulating substrate is fixed on a base plate made of, for example, copper, and the base plate is further fixed with bolts or the like so as to be pressed onto the radiation fins. Thermal conductive grease such as silicone grease is applied between the base plate and the heat radiating fins so as to improve thermal conductivity (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-23280

  The thermal conductive grease is applied on the heat radiation fin with a certain thickness so that voids such as bubbles do not appear in the heat conductive grease, and then the base plate is pressed against the heat radiation fin to push out the excess heat conductive grease. And thin. By reducing the thickness of the thermally conductive grease, the thermal conductivity is improved.

  However, in the conventional semiconductor device, excess thermal conductive grease is pushed out only from the periphery of the base plate, so it is necessary to press the base plate against the radiating fin with a large force to reduce the film thickness. There was a certain limit to the thinning of conductive grease.

  Accordingly, an object of the present invention is to provide a semiconductor device in which excess thermal conductive grease is efficiently extruded from between a base plate and a radiating fin to reduce the thickness of the thermal conductive grease.

  The present invention is a semiconductor device connected to a heat radiation fin via a thermally conductive grease, a base plate having a front surface and a back surface, an insulating substrate disposed on the surface of the base plate, and an insulating substrate The semiconductor device is disposed on the back surface of the base plate, and when the semiconductor device is connected to the heat radiating fin, a recess is provided in which a part of the heat conductive grease is pushed out. It is a semiconductor device.

  As described above, in the semiconductor device according to the present invention, the thermally conductive grease between the base plate and the heat radiating fin can be thinned, and a semiconductor device with high heat dissipation efficiency can be provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, “top”, “bottom”, “left”, “right” and names including these terms are used as appropriate, but these directions make it easy to understand the invention with reference to the drawings. Therefore, a mode in which the embodiment is inverted upside down or rotated in an arbitrary direction is naturally included in the technical scope of the present invention.

  FIG. 1 is a cross-sectional view of a semiconductor device according to an embodiment of the present invention, indicated as a whole by 100. FIG. 2 is a back view of a base plate included in the semiconductor device.

  The semiconductor device 100 includes an insulating substrate 1. The insulating substrate 1 has a structure having copper wiring patterns on both surfaces of an alumina substrate, for example. On the insulating substrate 1, a semiconductor element 2 such as an IGBT or a free wheel diode is fixed. The semiconductor element 2 and the wiring pattern of the insulating substrate 1 are electrically connected by a bonding wire or the like (not shown).

  The insulating substrate 1 is attached on a base plate 6 made of, for example, copper. Furthermore, the base plate 6 is attached to a heat radiating member, for example, a heat radiating fin 8 made of aluminum via a heat conductive grease 9. The base plate 6 is fixed so as to be pressed against the radiating fins 8 by, for example, bolts and nuts (not shown). For example, silicone grease is used as the thermally conductive grease 9.

  On the base plate 6, a case portion 3 provided along the periphery and a lid portion 4 that closes the case portion 3 at the top are provided. The case portion 3 is filled with silicon gel 5 so as to cover the semiconductor element 2.

  Further, the base plate 6 is provided with a recess 7 as shown in FIG. In FIG. 1, the recess 7 is arranged in a direction perpendicular to the paper surface and has open ends on both sides of the base plate 6.

  The heat conductive grease 9 is applied thickly on the heat radiation fin 8 so that voids such as bubbles cannot be formed in the heat conductive grease 9. Subsequently, as described above, the base plate 6 is fixed so as to be pressed against the heat radiating fins 8, so that excess heat conductive grease 9 protrudes from between the heat radiating fins 8 and the base plate 6. 9 is thinned.

In the semiconductor device 100, since the concave portion 7 is provided on the back surface of the base plate 6, excess heat conductive grease 9 is pushed out not only around the base plate 6 but also into the concave portion 7. That is, by providing the recess 7 on the back surface of the base plate 6, when the base plate 6 is pressed against the radiating fins 8 with a predetermined force, it is possible to push out a larger amount of excess thermal conductive grease 9.
As a result, the thermal conductive grease 9 between the radiation fins 8 and the base plate 6 is made thinner, and the thermal conductivity between the radiation fins 8 and the base plate 6 is improved.

  In addition, the position of the recess 7 formed on the back surface of the base plate 6 is at least below the insulating substrate 1 (indicated by the broken line 1 in FIG. 2) (a region facing the insulating substrate 1 with the base plate 6 in between). It is necessary to provide as follows. Further, it is preferable to avoid the region directly below the semiconductor element 2 (indicated by the broken line 2 in FIG. 2) mounted on the insulating substrate 1 and to provide it in the vicinity or in the vicinity thereof. This is because the thermal conductive grease 9 is thinned in the region immediately below the semiconductor element 2 (for example, when the thickness at the time of application is 200 μm, the thickness is reduced to 50 to 100 μm or less by bonding by pressing. This is to improve the heat dissipation efficiency.

Therefore, for example, as shown in FIG. 2, when a plurality of semiconductor elements 2 are arranged on the insulating substrate 1, below the region sandwiched between the semiconductor elements 2 (semiconductor elements sandwiching the base plate 6). 2 and a region sandwiched between the semiconductor elements 2 are preferably provided with a recess 7 below a region on the opposite side of the semiconductor element 2.
As shown in FIG. 2, the recess 7 is preferably a substantially linear groove having open end portions on both sides of the base plate 6. This is because the recess 7 can be easily manufactured and the cost can be reduced.

FIG. 3 is a cross-sectional view of FIG. 2 when viewed in the AA direction. As shown in FIG. 3, the recess 7 is composed of a substantially straight groove having opening ends on both side surfaces of the base plate 6, and the depth of the groove is shallowest in the vicinity of the center of the two opening ends. It gradually becomes deeper toward the end.
By having such a concave portion 7, when the base plate 6 is pressed against the heat radiating fin 8, air is quickly discharged from the concave portion 7, so that the work efficiency of attaching the base plate 6 to the radiating fin 8 is improved. Can be made.

  FIG. 4 is a back view of another base plate 6 included in the semiconductor device 100 according to the present embodiment. The base plate 6 shown in FIG. 4 has a recess 17 in the same direction as the base plate 6 shown in FIG.

  FIG. 5 is a back view of another base plate 6 included in the semiconductor device 100 according to the present embodiment. In the base plate 6 of FIG. 5, a recess 27 is provided along the periphery of the base plate 6.

  In addition, the recessed part provided in the back surface of the base board 6 is not limited to the structure shown in FIGS. 2-5, If it is the structure which can escape an excess thermal conductive grease, it is another shape. It doesn't matter.

  In addition, the recess 7 can be provided in the heat radiating fin 8, but it is provided in the base plate 6 in order to accurately place the recess 7 below the insulating substrate 1 or below the region sandwiched between the plurality of semiconductor elements 2. Is preferred.

  Note that the semiconductor device 100 is subject to transaction in both the state where the heat radiating phone 8 is not attached and the state where it is attached, and is sold.

It is sectional drawing of the semiconductor device concerning embodiment of this invention. It is a reverse view of the base board contained in the semiconductor device concerning embodiment of this invention. It is sectional drawing of the base board contained in the semiconductor device concerning embodiment of this invention. It is a reverse view of the other base board contained in the semiconductor device concerning embodiment of this invention. It is a reverse view of the other base board contained in the semiconductor device concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation substrate, 2 Semiconductor element, 3 Case part, 4 Cover part, 5 Silicon gel, 6 Base plate, 7 Recessed part, 8 Radiation fin, 9 Thermally conductive grease, 100 Semiconductor device.

Claims (6)

A semiconductor device connected to a heat dissipation fin via a thermal conductive grease,
A base plate having a front surface and a back surface;
An insulating substrate disposed on the surface of the base plate;
A semiconductor element disposed on the insulating substrate,
A semiconductor device characterized in that a recess is provided on the back surface of the base plate to allow a part of the thermally conductive grease to be pushed into the semiconductor device when the semiconductor device is connected to the radiating fin.   The semiconductor device according to claim 1, wherein the recess is provided at a position facing the insulating substrate across the base plate.   2. The semiconductor device according to claim 1, wherein the recess is provided at a position facing the insulating substrate excluding a region where the semiconductor element is disposed across the base plate.   The semiconductor device according to claim 1, wherein the concave portion is formed by a substantially linear groove having open end portions on opposite side surfaces of the base plate.   The semiconductor device according to claim 4, wherein the recess gradually becomes deeper from a substantially center of the two opening end portions toward the opening end portion. A semiconductor device according to any one of claims 1 to 5;
A heat dissipating fin connected to the back surface of the base plate included in the semiconductor device via a heat conductive grease;
A semiconductor device with a heat dissipation mechanism, wherein the thermally conductive grease is extruded into the recess from between the base plate and the heat dissipation fin.

Images