JP4469101B2 - Electronic circuit device having heat dissipation structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat dissipation structure of an electronic circuit device in which, for example, an amplifier, an oscillator, a modulator, or the like used in a transmission unit of a communication device is mounted. In particular, the present invention relates to a transistor, a field effect transistor (hereinafter referred to as FET), The present invention relates to an improvement in a heat radiation cooling structure of an electronic circuit device such as a power amplifier or a modulator in which a power semiconductor active element is mounted on a printed board.
[0002]
[Prior art]
FIG. 3 is a perspective view showing an example of a heat dissipation structure of a conventional electronic circuit device with a part broken away, and FIG. 4 is a cross-sectional view illustrating the heat dissipation action of the same conventional example. In these drawings, 1 is a printed circuit board, 2 is a high-power active element serving as a heat source, for example, a flat package type active element in which a semiconductor element is accommodated in a resin mold or a ceramic package, and 3 is an active element 2 A heat dissipating base plate attached to the back surface, 4 is a metal heat dissipating member having a number of fin-shaped heat dissipating fins on the bottom surface, and 5 is a shield case.
[0003]
The printed circuit board 1 is fixed to the upper surface of the radiator 4 together with the shield case 5 with a small screw. The printed circuit board 1 is provided with a square hole slightly larger than the outer dimensions of the package of the active element 2 and the base plate to be mounted, and the package and base plate portion of the active element 2 are loosely fitted (slowly passed) into the square hole. In such a state, the terminals protruding on both sides of the active element 2 are connected to lands (not shown) on the upper surface of the printed circuit board 1. In this state, the bottom surface of the base plate 3 of the active element 2 protrudes downward from the bottom surface of the printed circuit board 1 and becomes convex.
[0004]
A recess having a size into which the base plate 3 is fitted is provided on the upper surface of the heat dissipating member 4 that comes into contact with the base plate 3 protruding below the active element 2 so that the protruding height of the base plate 3 is equal to the depth of the recess of the heat dissipating member 4. Thus, the base plate 3 and the concave portion on the upper surface of the radiator 4 are arranged in close contact with each other without applying unnecessary stress to the terminals of the active element 2.
Depending on the thickness of the base plate 3 of the element 2 and the thickness of the printed circuit board 1, the concave portion on the upper surface of the heat radiator 4 may be flat or convex. At both the above positions, both ends of the base plate 3 are fixed to the radiator 4 with small screws so that the printed circuit board 1 and the base plate 3 are both in close contact with the radiator 4.
[0005]
The upper surface of the printed circuit board 1 is surrounded by a shield case 5 and covered with a cover.
[0006]
In such a conventional configuration, since the space above the active element 2 having the base plate 3 is covered with the shield case 5 and the cover, the heat generated by the active element 2 is not dissipated upward, and the dotted line in FIG. As indicated by the arrows, the heat conduction from the base plate 3 to the heat radiating body 4 is dissipated from the heat radiating fins on the lower side of the heat radiating body 4 to the outside air. That is, as shown in FIG. 4, the heat generation by the active element 2 is a heat dissipation structure that dissipates only in the lower direction by heat conduction.
[0007]
[Problems to be solved by the invention]
However, in the above conventional heat dissipation structure, there is only a heat conduction path for releasing the heat generated by the active element 2 through the printed circuit board 1 and the base plate 3 to the heat dissipating fins of the lower heat dissipating element 4, so that a higher output active element is mounted. In this case, there is a problem in that the amount of heat radiation is insufficient and the temperature rise cannot be suppressed, and it is necessary to increase the area of the heat dissipating body, which limits the downsizing of the device.
[0008]
In order to solve the above-described conventional problems, the present invention increases the heat dissipation path from the active element and enhances the cooling effect, thereby reducing the size and increasing the output of the active element mounting device such as an amplifier. It is an object of the present invention to provide an electronic circuit device having:
[0009]
[Means for Solving the Problems]
The present invention provides a heat dissipation structure for an electronic circuit device such as an amplifier in which high-power active elements such as transistors and FETs are mounted on a printed circuit board. In addition to the conventional heat dissipation structure by heat conduction, the printed circuit board 1 and the heat radiator 4 Between the two, a gap serving as a cooling ventilation path is provided, and a heat dissipation structure by convection is added.
[0010]
Specifically, an electronic circuit device having a heat dissipation structure according to the present invention includes a heat radiator having a plurality of fin-shaped heat radiation fins provided on the back surface and an active element having a heat dissipation base plate mounted on the back surface. A printed circuit board fixed to the upper surface of the substrate, and a shield cover covering the printed circuit board,
The terminal of the active element is connected to the printed circuit board, and the base plate is screwed to the upper surface of the heat dissipating member through the hole of the printed circuit board, so that conduction heat from the base plate due to heat generation of the active element is generated. An electronic circuit device having a heat dissipation structure that dissipates into the outside air through the heat radiator,
The printed circuit board is fixed by a substrate mounting portion having a predetermined height provided on the upper surface of the heat radiating body, and is formed around the base plate screwed to the heat radiating body, and the heat radiating body. The heat generation of the active element is dissipated by convection from the base plate to the outside air on the side surface through a gap between the base plate and the outside air.
Furthermore, the heat dissipating body is characterized in that a plurality of fin-shaped heat dissipating fins are provided on the upper surface facing the gap.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an embodiment of the present invention with a part thereof broken, and FIG. 2 is a cross-sectional view for explaining the heat radiation action of the present invention. In FIG. 1, the same parts as those in the conventional example of FIGS. 6 is a fin-like heat dissipating fin provided on the upper surface of the heat dissipating body 4, 7 is a board mounting portion, and 8 is a gap. The active element 2 is loosely fitted into the square hole of the printed circuit board 1 (is loosely passed), and only its terminal is connected to the land on the back surface of the printed circuit board 1. In this state, the bottom surface of the base plate 3 of the active element 2 is convex downward from the bottom surface of the printed circuit board 1 as in the conventional configuration.
[0012]
Substrate attachment portions 7 provided at a plurality of positions on the upper surface of the heat radiating body 4 in order to fix the printed circuit board 1 to the heat radiating body 4 are cylindrical and have a height that is the same as the protruding height of the base plate 3 downward. When the printed board 1 is attached to the board attaching portion 7 of the radiator 4, a gap 8 having the height of the board attaching portion 7 is formed between the printed board 1 and the radiator 4. In this state, the bottom surface of the base plate 3 is in close contact with the radiator 4 and is fixed to the radiator 4 without applying unnecessary stress to the terminals of the element 2. In this case, a recess for fitting the base plate 3 on the upper surface of the radiator 4 becomes unnecessary.
[0013]
However, depending on the thickness of the base plate 3 of the active element 2 and the thickness of the printed circuit board 1, the gap 8 may be provided by making the base plate contact portion of the radiator 4 flat or convex.
[0014]
In addition to the above heat dissipation structure, as shown in FIGS. 1 and 2, a heat dissipating fin 6 having a height substantially the same as the height of the board mounting portion 7 is provided on the side of the upper surface of the heat dissipating body 4 facing the gap 8. Can further improve the heat dissipation and cooling effect.
[0015]
With the above configuration, the base plate 3 that is at the highest temperature due to heat generated by the active element 2 and the vicinity of the contact portion between the radiator 4 and the base plate 3 are opened to the outside air on the side surface by the air gap 8. As shown by the arrows, a heat dissipation structure is realized by convection in the front, rear, left, right, and horizontal directions. Furthermore, it is more effective to provide the radiation fins 6 on the active element 2 side of the upper surface of the radiator 4.
Note that the heat radiation structure in the lower direction for conducting heat from the base plate 3 to the heat radiating body 4 and escaping to the outside air from the heat radiating fins on the lower surface of the heat radiating body 4 is the same as the conventional one.
[0016]
【The invention's effect】
As described above in detail, by implementing the present invention, a high-power semiconductor active element 2 such as a transistor or FET is mounted on the printed circuit board 1, and the base plate 3 of the active element 2 is mounted under the printed circuit board 1. In the cooling structure of an electronic circuit mounting apparatus such as an amplifier that radiates heat while being fixed to the radiator 4, since a heat dissipation structure that releases heat by convection from the vicinity of the base plate 3 of the active element 2 having the highest temperature is added, an even higher cooling effect is obtained. It is done.
As a result, an extremely excellent effect in practical use can be obtained in that downsizing and high output of a high-power electronic circuit mounting device such as a power amplifier are promoted.
[Brief description of the drawings]
FIG. 1 is a partially broken perspective view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating the heat dissipation action of the present invention.
FIG. 3 is a partially broken perspective view showing a conventional example.
FIG. 4 is a cross-sectional view for explaining the heat radiation action of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Element 3 Base plate 4 Radiator 5 Shield case 6 Radiation fin 7 Printed circuit board attachment part 8 Air gap

Claims (1)

A heat sink provided with a plurality of fin-like heat dissipating fins on the back surface, a printed circuit board on which an active element having a base plate for heat dissipation is mounted on the back surface and fixed on the upper surface of the heat dissipator, and covers the printed circuit board With a shield cover,
The terminal of the active element is connected to the printed circuit board, and the base plate is screwed onto the upper surface of the heat radiating body without applying unnecessary stress to the terminal of the active element by loosely fitting into the hole of the printed circuit board. , An electronic circuit device having a heat dissipation structure that dissipates conduction heat from the base plate due to heat generation of the active element to the outside air through the heat dissipation body,
The printed circuit board is fixed by a substrate mounting portion having a predetermined height provided on the upper surface of the heat radiating body, and is formed around the base plate screwed to the heat radiating body, and the heat radiating body. An electronic circuit device having a heat dissipation structure characterized in that heat generated by the active element is dissipated by convection from the base plate to the outside air on the side surface by using a gap as a ventilation path.

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