JPH05327250A - Heat radiating device for electronic equipment - Google Patents

Abstract

PURPOSE:To improve a heat radiating efficiency and assembly characteristics of a high heating element such as ICs and semiconductor devices, or the like, mounted on a printed board. CONSTITUTION:A hole is opened in a printed board 20 positioned below an electronic component 21, and a heat sink 24 is arranged to pass through the hole between the electronic component and a heat-conductive cover 23 below the board. This heat sink causes heat generated by the electronic component to be radiated from a lower part of the electronic component having a small heat resistance to the printed board and the heat-conductive cover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation device for cooling high heat generating elements such as ICs and semiconductor elements mounted on a printed circuit board.

[0002]

2. Description of the Related Art In recent years, as the speed and integration of semiconductor elements have increased, the power consumption of a single semiconductor element has increased, and the reliability of the semiconductor element has often decreased. Conventionally, in order to cool an electronic device including a high heat-generating element, it is necessary to use a heater as shown in FIG.
As shown in, the electronic component 1 is mounted with the cooling radiating fins 2 for use.

As a further advanced technique, for example, there is a heat dissipation device for electronic equipment disclosed in Japanese Utility Model Publication No. 2-5578. FIG. 6 is a front view thereof, and FIG. 7 is an enlarged side view of a main part. In the figure, 3 is a printed circuit board, 4 is an electronic component mounted on this printed circuit board 3, and 5 is a shield cover which covers the upper part of the printed circuit board 3. Further, 7 is a screw type heat sink for radiating heat of the electronic component, 8 is a fixing plate on the upper surface, 9 is a heat sink for fitting with the screw type heat sink 7 and radiating heat to the shield upper cover 5, 6 is a terminal of the electronic component 4. The lead pins are shown and each has thermal conductivity. 10 is a lock screw for preventing the screw type heat sink 7 from loosening, 11 is an electronic component 4 and the screw type heat sink 7.
It is a rubber with good heat conduction to increase the contact area with.

Next, the assembling operation of the heat dissipation device for electronic equipment will be described. First, the screw heat sink 7 is screwed into the screw portion of the heat sink 9 through the hole 5a in the upper portion of the upper shield cover 5, and the electronic component 4 is tightened. Next, the upper fixing plate 8 is placed on the shield upper cover 5, and the lock screw 10 is inserted into the hole 8a from above the upper fixing plate 8 and screwed into the female screw 7c to be fixed. In this way, the heat generated from the electronic component 4 is radiated from the upper portion of the electronic component 4 to the shield upper cover 5 by the screw heat sink 7 and the heat sink 9. The reason why the heat sink is screwed and fixed by the lock screw 10 is to adjust the height b between the electronic component 4 and the shield upper cover 5.

The conventional printed circuit board has a shield upper cover 13 and a shield lower cover 14 as shown in FIG.
The shield upper cover 13 and the shield lower cover 14 prevent electrostatic breakdown of the electronic component 15 caused by contact with the terminal lead pins 16 of the electronic component 15 on the lower side of the printed circuit board 12. It is installed for the purpose of blocking the generated radio waves.

[0006]

Since the conventional heat dissipation device for electronic equipment is configured as described above, the following can be said. First, FIG. 9 shows a cross-sectional view of an electronic component of a laminated ceramic package as an example of the electronic component. As can be seen from this figure, the upper portion 18 of the chip 17 is sealed with a vacuum and the lower portion of the chip 17 is lower. Since 19 is an alumina body, the thermal resistance inside the electronic component is chip 17
The lower portion 19 of the chip 17 is smaller than the upper portion 18 of the. Therefore, the conventional heat dissipation device for electronic devices has a problem that heat generated from electronic components cannot be sufficiently dissipated. Second, the package thickness a of the electronic component 4 shown in FIG.
Since it depends on the electronic component 4, it is necessary to adjust the height b of the electronic component 4 and the shield upper cover 5, and therefore the heat sink has a screw type structure. Therefore, special processing of the heat sink and fine adjustment of the height b are required. The work of adjustment is required and the cost becomes high. Thirdly, since the printed circuit board is covered by the shield upper cover and the shield lower cover,
There is a problem that heat is trapped inside the upper shield cover and the lower shield cover, the temperature of the internal air rises, and malfunctions and deterioration of electronic components are promoted.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a heat dissipation device for electronic equipment, which improves heat dissipation effect and facilitates assembly and adjustment.

[0008]

The heat dissipation device for electronic equipment according to the present invention allows heat to escape from the lower part of the electronic component having a small thermal resistance and facilitates height adjustment of the electronic component and the heat conductive cover. , A thermal bonding member (heat sink) having a certain thickness is contacted between the lower part of the electronic component and the printed circuit board, and a printed circuit board under the electronic component is provided with a hole. The heat generated from the electronic component is made to escape to the printed circuit board and the heat conductive cover by bringing the above-mentioned thermal bonding member into contact with the heat conductive cover covering the lower part.

[0009]

In the heat dissipation device for electronic equipment according to the present invention, the thermal bonding member is placed under the electronic component having a small internal thermal resistance, so that the heat from the lower portion of the electronic component is released to the external bonding member. By contacting the bonding member with the printed circuit board and the heat conductive cover, heat is radiated not only to the heat conductive cover but also to the printed circuit board, and it is possible to obtain a heat dissipation effect higher than conventional. In addition, the gap between the electronic component and the printed circuit board is almost the same regardless of the electronic component, and since the printed circuit board and the thermal conductive cover are also constant, the length between the electronic component and the printed circuit board and the printed circuit board A joining member having a fixed length between the conductive covers can be used, adjustment for contacting the joining member with the heat conductive cover is facilitated, and cost such as processing cost can be reduced.

[0010]

【Example】

Example 1. FIG. 1 is a front view showing an embodiment of the present invention. In the figure, 20 is a printed circuit board, 21 is an electronic component mounted on this printed circuit board 20, and 22 is a shield cover which covers the upper part of the printed circuit board 20. , 23 are shield lower covers that cover the lower part of the printed circuit board 20. 24
As will be described in detail later, a heat sink (joint member) for releasing heat generated from the electronic component 21, 25 is a terminal lead pin of the electronic component 21, and 26 is a fixing screw for fixing the heat sink 24, each having thermal conductivity. ing. 2 is an enlarged cross-sectional view of the main part of FIG. 1, and FIG. 3 is a perspective view of the heat sink 24.

The details of the structure will be described below. First, the length of the gap c between the electronic component 21 and the printed circuit board 20, and the gap d between the printed circuit board 20 and the shield lower cover 23.
The heat sink 24 having the female screw 28 is prepared according to the above. The heat sink 24 is connected to the printed circuit board 2
It is inserted into the hole 20a of 0 and the electronic component 21 is mounted from above. At this time, since the gap c between the electronic component 21 and the printed circuit board 20 is almost the same regardless of the electronic component 21,
The thickness of the heat sink 24 in contact with the electronic component 21 and the printed circuit board 20 can be fixed to c. Even if the gap between the electronic component 21 and the printed circuit board 20 is smaller than c, there is no problem because the length e of the terminal lead pin 25 of the electronic component 21 has a sufficient margin. By arranging the joining member under the electronic component in this manner, the height of the electronic component 4 and the shield cover 5 which is required because the thickness of the package is different for each electronic component 4 in FIG. 7 of the related art. The need for adjusting the heat sink 24, such as adjusting the height, is eliminated.
In addition, since the heat sink 24 is in contact with the lower portion of the electronic component 21 having a smaller internal thermal resistance than the upper portion of the electronic component 21, it is possible to expect a heat radiation effect higher than that of the conventional technique.
At this time, in order to increase the contact surface area between the heat sink 24 and the electronic component 21 to increase the number of contact points, the electronic component 2
A heat conductive rubber 27 may be inserted between the heat sink 24 and the heat sink 24, and since the heat sink 24 is brought into contact with the printed circuit board 20, heat conduction to the printed circuit board 20 is also increased. Further, as an example of a method of fixing the heat sink 24, there is the following method. The tip of the heat sink 24 is masked to prevent the solder from adhering, and the top of the electronic component 21 is pressed to flow into the solder flow.
1. A method of fixing the heat sink 24 by soldering. By fixing the heat sink 24 by soldering in this manner, the contact between the electronic component 21 and the printed circuit board 20 becomes reliable. Further, when attaching the upper shield cover 22 and the lower shield cover 23, by fixing the heat sink 24 with the fixing screw 26 from the hole 23a of the lower shield cover 23, the heat sink 24 is surely brought into contact with the lower shield cover 23, and the lower shield cover 23 is secured. Improves heat conduction to the cover 23.

Example 2. 4A and 4B are perspective views showing the shield upper cover 29 and the shield lower cover 30. The shield upper cover 22 and the shield lower cover 23 shown in the first embodiment are formed into a stitch shape as shown in FIG. With this configuration, the internal air permeability is improved, the temperature rise inside these shield covers can be suppressed, and the heat dissipation effect of electronic components can be improved.

[0013]

As described above, according to the present invention, the heat radiation effect can be improved by letting the heat escape from the lower part of the electronic component having a smaller thermal resistance than the upper part of the electronic component through the heat sink, and the heat sink can be further provided. Since the printed circuit board is also in contact with the printed circuit board, heat can be dissipated not only to the heat conductive cover but also to the printed circuit board, and a higher heat dissipation effect can be obtained. In addition, by arranging a heat sink between the lower part of the electronic component and the printed circuit board, the height adjustment between the electronic component and the thermal conductive cover, which was required in the prior art due to the different thickness of the package for each electronic component, is eliminated. Also, there is an effect that the cost such as the processing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing a heat dissipation device of an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

3 is a perspective view showing the heat sink of FIG. 1. FIG.

FIG. 4 is a perspective view of a shield upper cover a and a shield lower cover b according to another embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a conventional heat dissipation device.

FIG. 6 is a front view showing another example of a conventional heat dissipation device.

7 is a cross-sectional view showing a main part of the heat dissipation device of FIG.

FIG. 8 is a front view showing an example of a conventional heat dissipation device.

FIG. 9 is a cross-sectional view showing an example of an electronic component.

[Explanation of symbols]

 20 Printed Circuit Board 21 Electronic Component 24 Heat Sink 26 Fixing Screw 22,29 Shield Upper Cover 23,30 Shield Lower Cover

Claims (2)

[Claims] 1. A semiconductor device comprising a printed circuit board, an electronic component mounted on the circuit board, and a heat conductive cover covering the upper and lower parts of the circuit board, the electronic device passing through a hole provided in the circuit board. A heat sink disposed between the component and the lower thermal conductive cover is provided, and heat generated in the electronic component is radiated from the lower portion of the electronic component to the printed circuit board and the thermal conductive cover via the heat sink. Characteristic heat dissipation device for electronic equipment. 2. The heat dissipation device for electronic equipment according to claim 1, wherein the heat conductive cover for covering the substrate is formed in a stitch shape.