JPH06177297A - Cooling structure for electronic device - Google Patents

Abstract

PURPOSE:To provide a cooling structure for an electronic device, in which heat is dissipated away from the electronic device on a metal block to avoid adverse effects due to the vibrations and thermal stress on the dissipation side. CONSTITUTION:An electronic device 3 is attached to a metal block 4 that is connected with a heat-receiving part 12a of a heat pipe 12 through an elastic member 6 of good thermal conductor. The heat generated from the electronic device is transferred through the metal block 4 and elastic member 6 and dissipated by the heat pipe 12. Since the electric member absorbs the vibrations and thermal stress of the heat pipe, the electronic device on the metal block is not affected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for cooling electronic parts mounted on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, in this type of cooling structure, a heat sink is generally used to radiate heat. If the electronic component is small and its heat generation is relatively small, the area occupied by the heat sink on the printed circuit board is not so large, so the small heat sink is mounted on the printed circuit board in consideration of the cost reduction due to automatic mounting. Has been. On the other hand, in the case of a medium-sized electronic component, the amount of heat generated increases and the size of the heat sink also increases. Therefore, the heat sink is mounted outside the printed circuit board as much as possible in order to prevent the printed circuit board from increasing in size. In that case, if there is a margin in heat dissipation design, the heat sink is attached inside the component case, but if not, it is attached outside the component case.

Electronic parts may be directly attached to a heat sink outside the printed circuit board. In this case, electrical wiring, connectors, etc. for connecting the electronic components and the printed circuit board are required, and the number of components increases. Since this electric wiring generally carries a high current, it is necessary to minimize the wiring length depending on the system. Therefore, the distance between the printed circuit board and the electronic component cannot be increased, and the mounting place of the electronic component or the like is limited.

Therefore, a cooling structure is adopted in which electronic parts are mounted on the printed circuit board and a heat sink is mounted outside the printed circuit board. An example thereof is shown in JP-A-63-254754.

In the electronic component cooling structure according to the above publication, a mounting hole is formed in the metal block on which the electronic component is mounted, and the heat receiving portion of the heat pipe is directly mounted in the mounting hole.

[0006]

However, since the metal block and the heat receiving portion of the heat pipe are integrally and closely contacted with each other, vibration or thermal stress of a heat sink or the like connected to the heat pipe is mediated by the metal block. It adversely affects electronic parts.

It is an object of the present invention to improve the connecting means between the metal block and the heat receiving portion to prevent the transmission of vibrations and thermal stress to electronic parts as much as possible.

[0008]

In the electronic component cooling structure according to the present invention, an electronic component is mounted on a metal block, and the metal block and the heat receiving portion of the radiator are connected via an elastic body having excellent thermal conductivity. Are connected.

[0009]

The heat generated in the electronic component is transferred to the metal block and further transferred to the heat receiving portion via the elastic body. Then, the heat is transferred to the radiator to be radiated. Vibrations and thermal stress of the radiator are absorbed by the elastic body, and therefore do not reach the electronic components on the metal block.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an electronic component cooling structure according to a first embodiment of the present invention will be described with reference to FIG.

An electronic component 3 such as a power transistor is mounted on the printed circuit board 2 in the component case 1, and a metal block 4 made of copper or the like is attached to the printed circuit board 2. The electronic component 3 is attached to the metal block 4. It is worn. A mounting hole 5 is formed in the metal block 4, and an elastic body 6 having good thermal conductivity is embedded in the mounting hole 5.

In this embodiment, a Fluoriner liquid heat sink manufactured by Sumitomo 3M Limited is used as the elastic body 6. In this elastic body 6, a perfluorocarbon liquid 8 having excellent thermal conductivity is contained in a closed bag 7 made of a multilayer film having good thermal conductivity. Although not shown, the multilayer film has a thickness of about 0.18 mm and is composed of an outer soft-flammable layer, an inner seal layer and a barrier layer between them, and each layer is made of a soft-flammable adhesive. It is joined.

The heat sink 9 is installed on the outside of the component case 1, and a mounting hole 10 is formed at the base thereof. An elastic body 11 similar to the elastic body 6 is embedded in the mounting hole 10. The heat sink 9 is made of copper or aluminum.

The heat pipe 12 is a well-known radiator, and although not shown, water and fluorocarbon liquid are sealed in a vacuum tube, and when one end of the tube is heated, the liquid evaporates at a relatively low temperature, The vapor becomes a pressure liquid and moves to the other end of the tube at the speed of sound. Then, when the other end of the tube is cooled, this vapor condenses, releasing latent heat and liquefying. The condensate is quickly refluxed through one end of the tube on the heating side through a wick inside the tube.

As described above, heat can be efficiently transferred in the heat pipe 12 without external force. The outer wall of the heat pipe 12 is made of copper or the like. The heat receiving portion 12 a is inserted into the component case 1 on one end side of the heat pipe 12 and attached to the elastic body 6 in the metal block 4.
Therefore, the elastic body 6 is deformed into a bowl shape, and the inner surface of the mounting hole 5 of the metal block 4 and the outer surface of the heat receiving portion 12 a of the heat pipe 12 come into close contact with the sealing bag 7 of the elastic body 6. On the other hand, the heat radiating portion 12b, which is the other end of the heat pipe 12, has the heat sink 9
The elastic body 11 is inserted into the inner elastic body 11 and is deformed like a bowl like the elastic body 6. The inner surface of the mounting hole 10 of the heat sink 9 and the heat dissipation portion 12b of the heat pipe 12
The outer surface of the elastic body 11 is in close contact with the sealing bag 7 of the elastic body 11.

The heat generated in the electronic component 3 is generated by the metal block 4
To the heat receiving portion 12a of the heat pipe 12 via the sealing bag 7 of the elastic body 6 and the perfluorocarbon liquid 8.
Be transmitted to. Then, the heat is transferred from the heat radiating portion 12b of the heat pipe 12 to the heat sink 9 via the sealing bag 7 of the elastic body 11 and the perfluorocarbon liquid 8 and radiated.

In particular, the metal block 4 and the heat sink 9
And elastic body 6, 11 at the connecting portion between the heat pipe 12 and
The vibration of the heat sink 9 and the thermal stress of the heat pipe 12 are absorbed by these elastic bodies 6 and 11, and the adverse effect on the electronic component 3 on the metal block 4 is reduced.

By the way, in the above-mentioned prior art, when the material of the metal block and the material of the heat receiving portion of the heat pipe, and the material of the heat sink and the material of the heat radiating portion of the heat pipe are different from each other, depending on the external environment, the space between There is a risk of electrolytic corrosion due to the electrode potential difference at the contact part of
It was unreliable. If the metal block, the heat pipe, and the heat sink are made of the same material (usually copper) to avoid this electrolytic corrosion, the weight will be increased as compared with the case where the heat sink is made of aluminum. So, if you apply nickel plating etc. to those contact parts,
Although electrolytic corrosion can be avoided, it will increase costs.

However, in this embodiment, the metal block 4
Since the elastic bodies 6 and 11 (sealing bag 7 and perfluorocarbon liquid 8) are interposed between the heat sink 9 and the heat pipe 12, there is no risk of electrolytic corrosion even when the materials are different. Higher reliability.

On the other hand, if the elastic bodies 6 and 11 which are easily deformed are used, the heat pipe 12 can be easily attached and detached. Further, since the airtight bag 7 (multilayer film) of the elastic bodies 6 and 11 has an electrical insulating property, even if one heat sink 9 is shared by a plurality of systems, there is a risk of short circuit or electric noise intrusion. Not reliable.

In the second embodiment shown in FIG. 2, the elastic body 11 in the heat sink 9 has a cylindrical shape.
The heat radiating portion 12b of the heat pipe 12 inserted in the unit 1 can be moved along the axial direction A thereof. Further, in the third embodiment shown in FIG. 3, the elastic body 11 and the heat radiating portion 12b have a spherical bearing shape, and the heat radiating portion 12b is formed.
Are movable in the elastic body 11 in the circumferential direction B. Therefore, the degree of freedom between the heat sink 9 and the heat pipe 12 is increased, and the vibration of the heat sink 9 is more easily absorbed.

Although the heat pipe 12 is used in each of the above-described embodiments, it may be changed to another heat radiator having good heat conductivity. Further, in the above-described embodiment, the elastic body 6, 11 used is one in which the perfluorocarbon liquid 8 is housed in the closed bag 7, but it is not such a fluid, and the thermal conductivity is good and the electrical insulation is good. Certain elastic solids may be utilized. Further, the vehicle body may be used instead of the heat sink 9.

[0023]

According to the present invention, in the electronic component cooling structure of the type that radiates heat at a position separated from the electronic component on the metal block, the function of the elastic body having excellent thermal conductivity causes vibration and heat on the heat radiating side. Electronic components are less likely to be adversely affected by stress.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an electronic component cooling structure according to a first embodiment.

FIG. 2 is a schematic sectional view showing an electronic component cooling structure according to a second embodiment.

FIG. 3 is a schematic sectional view showing an electronic component cooling structure according to a third embodiment.

[Explanation of symbols]

2 printed circuit boards, 3 electronic components, 4 metal blocks,
5 mounting holes, 6 elastic body, 7 airtight bag, 8 perfluorocarbon liquid as fluid, 9 heat sink as radiator, 10 mounting hole, 11 elastic body, 12 heat pipe as radiator, 12a heat receiving part, 12b heat radiation Department.

Claims (1)

[Claims] 1. A metal block on which electronic components are mounted,
A cooling structure for an electronic component, comprising: a heat radiator having a heat receiving portion, wherein the metal block is connected to the heat receiving portion of the heat radiator via an elastic body having excellent thermal conductivity.