JPH06342992A - Radiating type circuit board - Google Patents

Abstract

PURPOSE:To enable monitoring of components on both faces and to make a printed circuit board excellent in heat radiation property by sandwiching and piling up radiation fins between two metal plates with printed circuit boards bonded on the outer faces and by inserting heat pipes into a part of holes of radiation fins. CONSTITUTION:Printed circuit boards 2A, 2B are bonded on the outer faces of metal plates 11A, 11B via adhesive layers 19, respectively. Radiation fins 13A, 13B are soldered to the inner faces of the metal plates 11A, 11B, respectively, and both radiation fins 13A, 13B are soldered on contact faces. Heat pipes 17 are inserted by contact with radiation fins into a part of holes 15 out of many ones 15 of of the radiation fins 13A, 13B, thereby making the other holes 15 serve as air vents. Therefore, heat of mounted heat generating components is absorbed by the metal plates 11A, 11B and transmitted to the radiation fins 13A, 13B and the heat pipes 17, so that heat is transported from high temperature zone to low temperature zone by the heat pipes 17 and radiated by air circulating through the holes 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiation type circuit board on which heat generating components are mounted.

[0002]

2. Description of the Related Art A conventional heat radiation type circuit board is generally a printed circuit board on one side of which a metal plate such as an aluminum plate is joined as a heat sink. However, since this type of heat dissipation type circuit board can mount components only on one side, it is difficult to increase the component mounting density.

As a modification of this, a heat dissipation type circuit board has been proposed in which a heat pipe is embedded in a metal plate and a printed circuit board is bonded to both surfaces of the metal plate so that components can be mounted on both surfaces. (Japanese Utility Model Publication No. 3-63964).

[0004]

However, in the structure in which the heat pipe is embedded in the metal plate and the printed circuit boards are joined to both surfaces of the metal plate, heat radiation from the plate surface of the metal plate is blocked by the printed circuit board. , I have to rely only on the heat pipe for heat dissipation,
It is difficult to improve heat dissipation efficiency. Also, because the heat pipe is bonded to the metal plate via an adhesive,
There is also a problem that the heat resistance until the heat absorbed by the metal plate is transferred to the working fluid in the heat pipe is large, and the function of the heat pipe cannot be fully exhibited.

An object of the present invention is to provide a heat dissipation type circuit board in which components can be mounted on both sides and which is excellent in heat dissipation, in view of the problems of the prior art.

[0006]

In order to achieve this object, a heat dissipation type circuit board according to claim 1 of the present invention comprises two metal plates having a printed circuit board bonded to the outer surface thereof, and a metal plate between the inner surfaces thereof. The heat radiation fins that are formed so that a large number of straight holes are formed when viewed in the direction parallel to the plate surface of the plate are laminated and integrated, and some of the many holes formed by the heat radiation fins have heat radiation fins. The heat pipe is inserted in close contact with and the other holes are used as air circulation holes.

According to a second aspect of the present invention, there is provided a heat dissipation type circuit board in which a printed circuit board is joined to both surfaces of a metal plate having a large number of straight holes in a direction parallel to the plate surface, and a part of the holes in the metal plate. A heat pipe is formed by adding a working fluid for a heat pipe to the both ends and sealing both ends of the hole, and the other holes are used as air circulation holes.

[0008]

According to the structure of claim 1, the heat absorbed from the heat generating component to the metal plate is transmitted from the metal plate to the radiation fin and the heat pipe, and is efficiently transported and dispersed from the high temperature portion to the low temperature portion by the heat pipe. At the same time, the heat is radiated by the air flowing through the large number of holes formed by the heat radiation fins.

According to the second aspect of the present invention, the heat absorbed from the heat-generating component to the metal plate is efficiently transported and dispersed from the high temperature portion to the low temperature portion by the heat pipe formed in the metal plate. Heat is radiated by the air flowing through the holes in the metal plate. Particularly, in the structure of claim 2, the heat absorbed by the metal plate directly heats the working fluid of the heat pipe, so that the heat transfer efficiency is high.

Therefore, even in the form in which the printed circuit boards are joined to both outer surfaces of the metal plate, it is possible to efficiently dissipate heat from the inner surface or the inside of the metal plate. It is desirable that the heat dissipation type circuit board of the present invention be used by forcibly circulating air through the air circulation holes or by arranging so that at least the air circulation holes are oriented vertically.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 show an embodiment (corresponding to claim 1) of the present invention. In the figure, 11A and 11B are two metal plates arranged opposite to each other, 13A is a heat radiation fin brazed to the inner surface of one metal plate 11A, and 13B is a heat radiation fin brazed to the inner surface of the other metal plate 11B. Is. The radiation fins 13A and 13B are also brazed to each other at their contact surfaces.

The metal plates 11A and 11B have a thickness of 1 mm, for example.
It is made of aluminum plate. The radiating fins 13A and 13B are, for example, aluminum plates having a thickness of about 0.3 mm formed into offset waveforms as shown in FIG. Such a radiation fin is manufactured by forming a dashed line slit in an aluminum plate and then pressing. This type of heat dissipation fin 13
When viewed in the direction of arrow R in FIG. 3, A and 13B have a large number of straight holes 15 as shown in FIG.

A heat pipe 17 is inserted in a part of the many holes 15 of the radiation fins 13A and 13B. When the heat pipe 17 is inserted into the hole 15, the heat radiation fin 13A,
It is made close to 13B so that there is no play.
FIG. 2 shows a state in which the heat pipe 17 is inserted into the holes 15 of the heat radiation fins 13A and 13B when viewed from a direction perpendicular to the plate surface. Since the holes 15 are not continuous, the heat pipe 17 is intermittently held by the radiation fins 13A and 13B. Radiating fins 13A, 13B and heat pipe 17
Are brazed as needed. The other hole 15 into which the heat pipe 17 is not inserted becomes an air circulation hole for cooling.

Printed circuit boards 21A and 21B are bonded to the outer surfaces of the metal plates 11A and 11B via an adhesive layer 19, respectively. The printed circuit boards 21A and 21B are ordinary ones, and have a structure in which copper foil circuit patterns 25 are formed on both surfaces of the insulating board 23 (in the case of a multilayer, also inside).

Since this heat dissipation type circuit board can mount electronic parts on the printed circuit boards 21A and 21B on both sides, it can be used for high density mounting. The printed circuit boards 21A and 21B have holes (not shown) at mounting positions of the heat generating components, and the packages of the heat generating components are directly fixed to the metal plates 11A and 11B. The heat pipe 17 can be inserted into the holes 15 of the radiating fins 13A and 13B after the components are mounted in order to avoid the influence of heat when the components are mounted.

The heat radiation type circuit board on which the components are mounted is set in the housing of the device or the like so that the holes 15 are oriented in the vertical direction.
The heat of the heat-generating component is absorbed by the metal plates 11A and 11B, transmitted to the heat radiation fins 13A and 13B and the heat pipe 17,
Heat is transferred from the high temperature portion to the low temperature portion by the heat pipe 17, and heat is radiated by the air flowing through the holes 15 in the heat radiation fins 13A and 13B. Therefore, even if the printed circuit boards 21A and 21B are arranged on both sides, heat can be efficiently dissipated. The holes for the heat radiation fins 13A and 13B
It is desirable to force the air into the 15 by a fan.

Next, another embodiment of the present invention (corresponding to claim 1) will be described with reference to FIG. 4, the same parts as those in FIG. 1 are designated by the same reference numerals. The major difference of this heat dissipation type circuit board from that of the above embodiment is that the printed circuit boards 21A and 21B on both sides are connected by a flexible portion 21C on one side of the metal plates 11A and 11B.

Such a heat dissipation type circuit board is made from the development board shown in FIG. That is, in the development board of FIG. 5, the radiation fins 13A and 13B are fixed to one surface of the metal plates 11A and 11B in the same manner as in the above embodiment, the heat pipe 17 is inserted, and the flexible portion 21C is provided on the other surface. The printed circuit boards 21A and 21B connected to each other are adhered via an adhesive layer 19. By bending the flexible portion 21C of the expanded board and overlapping the heat radiation fins 13A and 13B, a heat radiation type circuit board having printed circuit boards 21A and 21B on both sides as shown in FIG. 4 is obtained.

The advantage of the heat dissipation type circuit board of this embodiment is shown in FIG.
Since the components can be mounted in the state of the expanded substrate, the component mounting process (component mounting, reflow soldering) can be performed only once. The heat pipe 17 may be inserted after component mounting. After mounting the components, the flexible portion 21C is bent to be in the state of FIG. 4, but the radiating fins 13A and 13B which are overlapped may be partially joined by a brazing material or an adhesive material, or opened in a used state. If there is no fear, it is not necessary to join them.

In the above embodiment, the radiation fins 13A,
Although the offset waveform as shown in FIG. 3 was used as 13B, the shape of the radiation fin is not limited to this,
For example, it is also possible to use a straight corrugated mountain and valley. The point is that a straight hole can be formed in which the heat pipe can be inserted while being fixed to the metal plate.

Next, still another embodiment of the present invention (corresponding to claim 2) will be described with reference to FIGS. 6 and 7. This heat dissipation type circuit board uses a metal plate 27 in which a large number of holes 29 are formed in parallel. Such a metal plate 27 is manufactured as an integral body from the beginning by extrusion molding of aluminum, or is manufactured by laminating a plurality of aluminum plates having parallel holes and integrating them by brazing or the like.

Some of the plurality of holes 29 have sealing members 31A at both ends with the working liquid for the heat pipe filled therein.
The heat pipe 33 is sealed by 31B.
One sealing member 31A is fixed to one end side of the hole 29 by welding and completely seals one end side of the hole 29 from the beginning, while the other sealing member 31B is the other end side of the hole 29. When it is fixed by welding, it has a through hole, the inside of the hole 29 is decompressed through the through hole, the working fluid is injected, and then the structure is sealed by crushing or the like. The holes 29 other than the holes forming the heat pipe 33 are open at both ends and serve as air circulation holes for cooling.

Printed circuit boards 21A and 21B are bonded to both surfaces of the metal plate 27 with an adhesive layer 19 interposed therebetween.
The printed circuit boards 21A and 21B are the same as those in the above embodiment in that they are composed of an insulating board 23 and a copper foil circuit pattern 25.

This heat dissipation type circuit board is also used with heat generating components mounted on both sides as in the embodiment of FIG. In the case of this heat dissipation type circuit board, instead of inserting another heat pipe into the metal plate 27, the heat pipe 33 is integrally built in, so that the heat absorbed by the metal plate 27 from the heat generating component is generated. The working fluid in the heat pipe 33 is efficiently heated. Therefore, the efficiency of the heat pipe 33 is extremely high, and the heat dissipation is improved. The point that air is circulated through the holes 29 other than the holes constituting the heat pipe 33 to enhance the heat dissipation is the same as the above-mentioned embodiment.

[0025]

As described above, according to the present invention, even if the printed circuit boards are bonded to both outer surfaces of the metal plate, the heat pipe and the air circulation hole are formed inside or inside the metal plate. Therefore, good heat dissipation performance can be obtained by heat transfer by a heat pipe and cooling by air circulation. Therefore, heat generating components can be mounted on both surfaces, and a circuit board having excellent heat dissipation can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a heat dissipation type circuit board according to the present invention.

FIG. 2 is a sectional view taken along line P-P in FIG.

FIG. 3 is a perspective view of a heat dissipation fin used in the heat dissipation type circuit board of FIG.

FIG. 4 is a cross-sectional view showing another embodiment of the heat dissipation type circuit board according to the present invention.

5 is a transverse cross-sectional view showing a development board before the heat dissipation type circuit board of FIG. 4 is produced.

FIG. 6 is a vertical sectional view showing still another embodiment of the heat dissipation type circuit board according to the present invention.

7 is a transverse sectional view taken along the line QQ of FIG.

[Explanation of symbols]

 11A, 11B: Metal plates 13A, 13B: Radiating fins 15: Hole 17: Heat pipe 19: Adhesive layer 21A, 21B: Printed circuit board 27: Metal plate 29: Hole 31A, 31B: Sealing member 33: Heat pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H05K 1/02 F 8824-4E (72) Inventor Suemi Tanaka 2-6 Marunouchi, Chiyoda-ku, Tokyo No. 1 Inside Furukawa Electric Co., Ltd. (72) Inventor Kazuyuki Yamamori 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd.

Claims (2)

[Claims] 1. A radiating fin formed so that two metal plates having a printed circuit board bonded to the outer surface have a large number of straight holes between the inner surfaces when viewed from a direction parallel to the plate surfaces of the metal plates. Characterized in that the heat pipe is inserted in close contact with the radiating fins in a part of a large number of holes formed by the radiating fins, and the other holes are used as air circulation holes. Heat dissipation type circuit board. 2. A printed circuit board is bonded to both surfaces of a metal plate having a large number of straight holes in a direction parallel to the plate surface, and a working liquid for a heat pipe is put in some holes in the metal plate. A heat dissipation type circuit board, characterized in that a heat pipe is formed by sealing both ends of the hole, and the other holes are used as air circulation holes.