JP2001257490A - Heat dissipating structure for electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat dissipating structure for an electronic apparatus exhibiting high heat dissipation without applying an unnecessary stress to the electronic apparatus. SOLUTION: Upper surface of an electronic component 3 mounted on the surface of a printed wiring board 2 is covered with a heat dissipating sheet 1. A heat dissipating plate 4 is disposed on the side of the printed wiring board 2 opposite to the mounting side of the electronic component 3 and the heat dissipating sheet 1 is secured to the printed wiring board 2 by means of two securing screws 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiating structure of an electronic device for radiating heat of an electronic component mounted on a printed wiring board.

[0002]

2. Description of the Related Art In recent years, with the development of electronic technology, miniaturization of electronic equipment has been progressing. Under such circumstances, a surface mounting technique for mounting electronic components such as semiconductor elements on the surface of a printed wiring board has become common.

Heretofore, electronic components that can be surface-mounted have mainly been small devices for small signals, but recently, surface-mountable power devices that handle large currents have appeared. Since a large current flows through a power element, the power element generates a large amount of heat, and some power elements reach several tens to several tens of watts.

However, in general, it is essential to suppress the maximum temperature of a semiconductor element made of a semiconductor such as silicon from 150.degree. C. to about 200.degree. Therefore, in order to use a power element having a large amount of heat for a long time, efficient heat radiation from the power element is required.

In a conventional board insertion type electronic component, it is easy to attach a radiator due to its structure. However, in a surface mount type electronic component, the electronic component is generally attached to a printed wiring board by soldering. Since it is attached, it is difficult to attach the radiator directly to the electronic component.

FIG. 4A is a perspective view showing a heat dissipation structure of a conventional electronic device, and FIG. 4B is a sectional view of the structure shown in FIG.

Reference numeral 12 denotes a printed wiring board; 13, a surface-mount type electronic component; 14, a heat sink made of a thick metal plate;
Is a fixing screw for the heat sink 14, and 17 is the printed wiring board 12.
Are fixed screw holes provided in the heat sink 14.

In this heat dissipation structure, as shown in FIG. 4, the printed wiring board 12 on the side opposite to the side on which the electronic component 13 is mounted is mounted.
In addition, the heat sink 14 is fixed by two fixing screws 15 through a fixing screw hole 17 provided in the printed wiring board 12 and a fixing screw hole 18 provided in the heat sink 14.

FIG. 5A is a perspective view showing a heat dissipation structure of another conventional electronic device, and FIG. 5B is a sectional view of the structure of FIG. The same reference numerals as those in FIG. 4 indicate the same components.

In this heat radiation structure, as shown in FIG. 5, a heat radiation plate 16 made of a thin metal plate is brought into direct contact with the upper surface of the surface-mounted electronic component 13, and this heat radiation plate 16 is thickly dissipated to the printed wiring board 12. The plate 14 is fixed by two fixing screws 15 through a fixing screw hole 17 provided in the printed wiring board 12 and a fixing screw hole 18 provided in the heat sink 14.

[0011]

Normally, the printed wiring board 12 has a low thermal conductivity.
Since the adhesion between the heat sink and the heat radiating plate 14 is low, the heat radiating effect was not so good in the structure shown in FIG.

Further, since the electronic component 13 is positioned and fixed by the solder reflow method, the height and the position of the electronic component 13 have relatively large variations, so that the adhesiveness between the electronic component 13 and the heat radiating plate 16 is low. Even in the structure shown, the heat radiation effect was not so good. Further, when the heat radiating plate 16 is brought into contact with the upper surface of the electronic component 13 and attached, the electronic component 13
Unnecessary stress is applied to the electronic component 13 and the electronic component 13 is damaged.
Not desirable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat dissipation structure for electronic equipment which has a large heat dissipation effect and does not apply unnecessary stress to electronic parts.

[0014]

According to an aspect of the present invention, there is provided a heat radiation structure for an electronic device, comprising: a printed wiring board; an electronic component mounted on the printed wiring board; and at least one electronic component. A heat radiation sheet that covers the upper surface of the electronic component, and a heat radiation plate disposed on the printed wiring board on the side opposite to the electronic component mounting side, wherein the heat radiation sheet is fixed to the heat radiation plate or the printed wiring board. And

According to the present invention, with the above configuration, heat generated from the electronic component can be efficiently conducted to the heat radiating plate via the heat radiating sheet, and the heat radiating effect is large. Further, since the heat dissipation sheet is flexible, unnecessary stress is not applied to the electronic components.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

Embodiment 1 FIG. 1A is a perspective view showing a heat radiation structure of an electronic device according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view of the structure of FIG.

Reference numeral 2 denotes a printed wiring board, 3 denotes a surface-mount type electronic component such as a power element, 1 denotes a heat radiating sheet, 4 denotes a heat radiating plate made of aluminum, copper, or the like, 5 denotes a fixing screw of the heat radiating plate 4, and 6 denotes a fixing screw. A fixing screw hole of the heat radiating sheet 1, a fixing screw hole 7 provided on the printed wiring board 2, and a fixing screw hole 8 provided on the heat radiating plate 4.

In the heat dissipation structure of the electronic device according to the present embodiment,
As shown in FIG. 1, the upper surface of the electronic component 3 mounted on the printed wiring board 2 is covered with a heat radiation sheet 1, and a heat radiation plate 4 is arranged on the printed wiring board 2 on the side opposite to the side on which the electronic component 3 is mounted. The sheet 1 is fixed to the printed wiring board 2 by two fixing screws 5 through fixing screw holes 7 provided in the printed wiring board 2 and fixing screw holes 8 provided in the heat sink 4. With this configuration, heat generated from the electronic component 3 such as a power element can be efficiently conducted to the heat radiating plate 4 via the heat radiating sheet 1, and a structure having a high heat radiating effect can be provided.

The heat radiation sheet 1 has a high thermal conductivity,
Use one with high flexibility. For example, the material of the heat radiation sheet 1 is, for example, graphite. This graphite heat dissipation sheet 1 is a soft material such as paper,
The thermal conductivity in the sheet surface direction is at least three times that of aluminum.

For example, the mounting position of the electronic component 3 as a power element has a mounting deviation of about 0.5 mm in the vertical and horizontal directions. Since the heat radiating sheet 1 has flexibility, the mounting deviation in the upper, lower, left and right directions can be set as the deviation in the sheet surface direction of the heat radiating sheet 1. Then, the diameter D of the fixing screw hole 6 for attaching the heat radiation sheet 1 to the printed wiring board 2 is described.
Is larger than the diameter d of the screw portion of the fixing screw 5 to absorb the mounting deviation of the electronic component 3 in the vertical and horizontal directions,
Sufficient adhesion between the electronic component 3 and the heat dissipation sheet 1 can be ensured without applying unnecessary stress to the electronic component 3.

As the heat radiation sheet 1, a ceramic sheet, a silicon sheet, or the like can be used in addition to the graphite sheet, and the same effect can be obtained.

Embodiment 2 FIG. 2A is a perspective view showing a heat radiation structure of an electronic device according to Embodiment 2 of the present invention, and FIG. 2B is a sectional view of the structure of FIG.

In the first embodiment, the printed wiring board 2 is interposed between the heat radiating sheet 1 and the heat radiating plate 4, and the heat radiating sheet 1 is fixed to the printed wiring board 2 and the heat radiating plate 4 with the fixing screw 5. In the present embodiment, as shown in FIG. 2, a mounting hole 9 for mounting the heat radiating sheet 1 is opened in the printed wiring board 2, and the heat radiating sheet 1 is provided on the heat radiating plate 4 with the fixing screw 5. It is directly fixed through the fixing screw hole 8.

Hereinafter, the heat radiation sheet 1 according to the present embodiment will be described.
The method of fixing the above will be described.

First, two mounting holes 9 for mounting the heat radiating sheet 1 to the heat radiating plate 4 are provided in the vicinity of the electronic component 3 on the printed wiring board 2. This mounting hole 9 is provided to be larger than the contact surface of the heat radiation sheet 1.

Next, the electronic component 3 is mounted on the surface of the printed wiring board 2 by soldering or the like.

Next, a heat radiating plate 4 is arranged on the printed wiring board 2 on the side opposite to the side where the electronic components 3 are mounted, and the heat radiating sheet 1 is fixed to the heat radiating plate 4 through the mounting holes 9 of the printed wiring board 2. It is attached to the hole 8 with two fixing screws 5. Thereby, the heat radiation sheet 1 is directly contacted with the heat radiation plate 4 and fixed.

Also in this embodiment, the diameter D of the fixing screw hole 6 for attaching the heat radiation sheet 1 to the heat radiation plate 4 is made larger than the diameter d of the screw portion of the fixing screw 5 (see FIG. 1).

In this embodiment, the same operation and effect as those in the first embodiment can be obtained. However, in this embodiment, since the heat radiation sheet 1 is attached in direct contact with the heat radiation plate 4,
In this embodiment, the heat radiation effect is greater than in the first embodiment in which the heat radiation sheet 1 is attached to the heat radiation plate 4 via the printed wiring board 2.

Third Embodiment FIG. 3A is a perspective view showing a heat radiation structure of an electronic device according to a third embodiment of the present invention, and FIG. 3B is a sectional view of the structure of FIG.

In the present embodiment, the upper surfaces of the two electronic components 3 are covered with the heat radiation sheet 1 in the second embodiment, and the other configuration is the same as that of the second embodiment. It is needless to say that the upper surfaces of the two electronic components 3 are not limited to being covered with the heat radiation sheet 1, and the upper surfaces of three or more electronic components 3 may be covered with the heat radiation sheet 1.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is.

[0034]

As described above, according to the present invention,
The heat radiation characteristics of the electronic component mounted on the printed wiring board can be improved with a simple configuration, and therefore, the reliability of the electronic component can be improved, the life can be extended, and the size and cost of the electronic device can be reduced.

[Brief description of the drawings]

FIG. 1A is a perspective view illustrating a heat radiation structure of an electronic device according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of the structure of FIG.

FIG. 2A is a perspective view showing a heat radiation structure of an electronic device according to a second embodiment of the present invention, and FIG. 2B is a cross-sectional view of the structure of FIG.

FIG. 3A is a perspective view showing a heat radiation structure of an electronic device according to a third embodiment of the present invention, and FIG. 3B is a cross-sectional view of the structure of FIG.

4A is a perspective view showing a heat dissipation structure of a conventional electronic device, and FIG. 4B is a cross-sectional view of the structure of FIG.

FIG. 5A is a perspective view showing a heat dissipation structure of another conventional electronic device, and FIG. 5B is a cross-sectional view of the structure of FIG.

[Description of Signs] 1 ... Heat radiation sheet, 2 ... Printed wiring board, 3 ... Electronic component, 4 ... Heat radiation plate, 5 ... Fixed screw, 6 ... Fixed screw hole of heat radiation sheet, 7 ... Fixed screw hole of printed wiring board, 8: fixing screw hole of heat sink, 9: mounting hole.

Claims (1)

[Claims] 1. A printed wiring board, an electronic component mounted on the printed wiring board, a heat dissipation sheet covering an upper surface of at least one electronic component, and a side of the printed wiring board opposite to a mounting side of the electronic component. Wherein the heat radiating sheet is fixed to the heat radiating plate or the printed wiring board.