JPH064635Y2 - Heat sink mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field of the Invention> The present invention relates to a structure for firmly fixing a heat sink of a transistor to a circuit board.

<Prior Art> Since the circuit board is made of an insulating material such as synthetic resin or ceramic, it is not possible to form a screw on the circuit board itself, and the radiator of the transistor cannot be directly fixed to the circuit board. . Therefore, as shown in FIG. 3, the metal holding plate 4 having the mounting screw holes 3 is arranged in a portion facing the radiator 2 with the circuit board 1 interposed therebetween.
And the screw 6 through the screw hole 5 of the circuit board 1 to dissipate the radiator 2
It is screwed into the screw hole 7 of.

In this structure, the presser plate 4 is used to strengthen the screwing.
A thicker plate is used, the protrusions 8 are formed as shown in FIG. 4 (a), or the bent portions 9 are formed on both side edges as shown in FIG. 4 (b). It has a structure that uses deflection.

<Problems of Prior Art> In order to form the bent edge 8 or the projection 9 on the pressing plate, it is necessary to bend or press the pressing plate. Also, when mounting the radiator using the holding plate, you must pay attention to the front and back of the holding plate.

<Means for solving the problem> A solder buildup portion is formed on the mounting surface of the holding plate of the circuit board,
The pressing plate is brought into contact with the solder buildup portion so that the bending of the pressing plate can be used. Two or more solder build-up portions are formed at equal intervals around the periphery of the screws. Further, the solder build-up portion is formed at a position where it comes into contact with the outer periphery of the holding plate, and acts to prevent rotation of the holding plate when screwing.

<Advantage of the Invention> By forming a part of the wiring pattern on the surface of the circuit board also on the attachment surface of the holding plate, the solder build-up portion can be formed simultaneously with soldering the circuit board by the dipping method.

Since the holding plate can be lifted by the thickness of the solder rising portion due to the solder rising portion, the radiator can be firmly attached by utilizing the bending of the holding plate.

<Example> A wiring pattern 12 is formed on a circuit board 11 made of an insulating material by a printing method, and a land 13 for soldering is formed on a portion facing a mounting position of a radiator. The lands 13 are formed on both sides of the circuit board 11 with a little distance from the radiator mounting holes 19. Further, in order to prevent the pressing plate 17 from rotating, the land 13 is formed at a position in contact with the outer periphery of the pressing plate 17. After mounting the electronic components on the substrate 11, soldering is performed by a dipping method or another method. At this time, the solder raised portion 14 is formed on the land 13. Since the size and height of the solder raised portion are determined by the size of the land, the composition of the solder, the processing time of the solder, etc., it is designed in advance to a predetermined size. The anti-rotation solder build-up part is designed to be a little higher than the other solder build-up parts so as to come into contact with the side surface of the holding plate.

The radiator 16 of the transistor 15 and the holding plate 17 are aligned with each other, and then the screw 20 is passed through the screw hole 18 of the holding plate 17 and the hole 19 of the circuit board 11 and fixed to the screw hole 21 of the radiator 16. The pressing plate 17 is slightly lifted from the surface of the substrate 11 due to the solder build-up portion 14, and therefore the pressing plate is bent due to screwing, and the solder build-up portion 14 is deformed to be firmly fixed.

In order to prevent the pressing plate 17 from rotating due to vibration or shock during or after the mounting, one or more solder build-up portions 14 are formed on the outer periphery of the pressing plate 17. It is desirable that the anti-rotation solder build-up portion 14 be formed at a position as far as possible from the screw fastening position.

Although the above embodiment is attached by one screw, the present invention can be applied to a structure using two or more screws. Further, it is possible to implement the solder embossing section with two or more.

<Effects of the Invention> Since the present invention is mounted by using the solder build-up portion that is formed at the same time as the circuit board soldering process, a simple flat plate may be used as the holding plate, and thus the holding plate requires special processing. Not.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining the structure of an embodiment of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a sectional view showing a conventional structure, and FIG. 4 is a holding plate used in the conventional example. FIG. 11 ... Circuit board, 13 ... Land 14 ... Solder raised part, 16 ... Radiator 17 ... Press plate, 20 ... Screw

Claims (2)

[Scope of utility model registration request] 1. A circuit board, a radiator mounting hole formed at a predetermined position of the circuit board, and a surface on which a wiring pattern of the circuit board is formed apart from the hole and within a size of a holding plate. The solder build-up portion formed on the same surface, a holding plate arranged so as to abut the solder build-up portion, and a transistor and a radiator arranged on the back side of the circuit board, the holding plate, the circuit board, A radiator and mounting structure, characterized in that the transistor and the radiator are screwed with a screw penetrating the radiator mounting hole. 2. The radiator mounting structure according to claim 1, wherein a solder build-up portion is formed at a position in contact with the outer periphery of the holding plate.