JPH06112676A - Structure for attaching cooling fin - Google Patents

Abstract

PURPOSE:To provide a simple and reliable structure for attaching a cooling fin to a printed wiring board on which a surface-mounted-type electronic circuit element is mounted. CONSTITUTION:A structure for attaching a cooling fin comprises a radiating fin 2 having holes 3 at proper places, nut sections 5 formed in correspondence to the holes, and screws 4 which are driven into the nut sections through the holes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation fin mounting structure, and for example, in a printed wiring board having a surface mount type electronic circuit element mounted thereon, the radiation fin can be cooled more simply and surely. It relates to a mounting structure.

[0002]

2. Description of the Related Art In the conventional technique of this type, in order to obtain improved heat dissipation characteristics for a semiconductor circuit element mounted on a substrate such as a printed wiring board, a heat dissipation plate or a heat dissipation plate is provided through a heat conductive adhesive. It was done to fix the radiation fins. Further, in such a case, a required hole may be provided in both the substrate and the heat radiation fin, and a fixing operation may be performed using an appropriate screw and nut. FIG. 3 is a schematic configuration diagram of a conventional example according to the above technique. In FIG. 3A, the radiation fins 2 are mounted at appropriate places on the printed wiring board 1, and the holes 3 are provided so as to penetrate both of them. Then, the printed wiring board 1 and the radiation fins 2 are fixed to each other through the holes 3 with appropriate screws 4 and nuts 5. In FIG. 3B, the printed wiring board 1 and the heat radiation fins 2 are fixed to each other by six layers of required solder. In (C) of FIG. 3 which follows this, the surface mount type semiconductor circuit element 8 is mounted at an appropriate position on the printed wiring board 1, and the heat radiation fins 2 are mounted via an appropriate adhesive 7. .

By the way, the above-mentioned conventional technique has the following drawbacks. That is, when fixing the heat radiation fins to the printed wiring board with screws or nuts, it is necessary to provide holes in the heat radiation fins or the printed wiring board. For example, a multilayer printed wiring board was prepared. Even so, the degree of freedom of wiring is reduced due to the restriction of the position of the hole or the like. Further, when fixing the radiation fin to the printed wiring board using solder, it is difficult to heat the radiation fin itself, and therefore the soldering operation itself is difficult. Furthermore, when a radiation fin is fixed to the printed wiring board side by using a resin-based adhesive as the adhesive, the adhesive itself has poor thermal conductivity, and the adhesive is not directly attached to the semiconductor package. When doing so, too much cannot be expected due to the adhesive performance of the adhesive itself, the size of the parts to be incorporated together, and the like.

[0004]

As described above, in the above-mentioned prior art, when fixing the heat radiation fins to the printed wiring board by using screws or nuts, a multilayer printed wiring board is prepared. Even if you do so, the flexibility of wiring will decrease, and when fixing with solder, it will be difficult to heat the radiating fin itself and the soldering work itself will be difficult, and the resin-based adhesive When fixing using, there were some problems such that the thermal conductivity of the adhesive itself was poor and too much could not be expected.

The present invention has been made to solve the above-mentioned problems. For example, in a printed wiring board to which a surface-mounting type electronic circuit element is attached, reliable cooling can be achieved with a simple structure. It is an object of the present invention to provide a heat radiation fin attachment structure that is made possible.

[0006]

SUMMARY OF THE INVENTION A radiation fin mounting structure according to the present invention has a radiation fin 2 having a hole 3 in a proper position; a nut portion 5 provided on the printed wiring board 1 corresponding to the hole; And a screw 4 which penetrates to the nut portion through the hole portion.

[0007]

By adopting the above-mentioned means, according to the radiation fin mounting structure according to the present invention, the mounting on the printed wiring board is simplified and the degree of freedom of wiring of the printed wiring board itself is hindered. Does not occur. That is, in the radiating fin mounting structure according to the present invention, prior to mounting the radiating fins 2, the nut portion 5 for fixing the radiating fins 2 is mounted on the printed wiring board 1 together with other surface mounting components in advance. Therefore, unlike the conventional one, it is not necessary to separately provide a nut portion for fixing the heat radiation fin on the printed wiring board or the heat radiation target component. And since it is not necessary to provide a hole portion as a nut portion in the printed wiring board,
The wiring freedom of the printed wiring board is not impaired.
Similarly, it is not necessary to provide a hole as a nut for a heat radiation target component such as a QFP having a built-in heat radiation plate, and direct stress is applied to the heat radiation target component such as the QFP when fixing the heat radiation fin. Therefore, it is possible to maintain high reliability.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic explanatory view of an embodiment of a radiation fin mounting structure according to the present invention. Figure 1
In (A), the radiation fins 2 are mounted at appropriate places on the printed wiring board 1. The radiating fin 2 can be formed by extrusion molding of an aluminum alloy (aluminum copper alloy), for example. Further, a hole 3 is provided at an appropriate position of the heat radiation fin 2 by an appropriate means such as a drill. A semiconductor circuit element 8 is mounted at an appropriate position on the printed wiring board 1, and the hole portion 3 of the heat radiation fin 2 is provided.
The nut portion 5 is provided at a position corresponding to the above, and the printed wiring board 1 and the radiation fin 2 are fixed to each other through the hole portion 3 by an appropriate screw 4. The nut portion 5 is formed into a block shape based on a copper alloy or 4-2 alloy, and a required screw thread is cut by a drilling operation or the like. Then, nickel / tin / plating is applied to this portion to improve solderability and to improve its corrosion resistance. 1B and 1C each show a modified example of the nut portion. In FIG. 1B, a pair of pad-shaped nut portions 5B are provided as the nut portions. More specifically, the mounting nut portion is fixed to the pad-shaped portion by an appropriate operation such as soldering. Further, in FIG. 1C, a frame-shaped nut portion 5C is used and a hole portion provided at an appropriate position is used.

FIG. 2 is a schematic explanatory view of another embodiment of the radiation fin mounting structure according to the present invention. First, in FIG. 2A, a recess 2A is provided at the bottom of the heat dissipation fin 2, and an escape area for a semiconductor circuit component (not shown) is provided, for example. In FIG. 2B, the escape area as described above is not particularly provided. In both figures, part 2B
Can be used, for example, for reinforcement.

[0010]

As described in detail above, the printed wiring board according to the present invention does not need to be provided with a hole as a nut portion in the printed wiring board, so that the degree of freedom of wiring of the printed wiring board itself is high. In the same manner, since it is not necessary to provide a hole portion as a nut portion for a heat radiation target component such as a QFP having a heat radiation plate or the like built therein, the QFP or the like can be fixed when the heat radiation fin is fixed. There is an effect that stress is not directly applied to the heat radiation target component and the higher reliability can be maintained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of a radiation fin mounting structure according to the present invention.

FIG. 2 is a schematic explanatory view of another embodiment of the radiation fin mounting structure according to the present invention.

FIG. 3 is a schematic configuration diagram of a conventional example according to the above technique.

[Explanation of symbols]

 1: Printed wiring board; 2: Heat dissipation fin; 3: Hole portion; 4: Screw; 5: Nut portion; 8: Semiconductor circuit element;

Claims (1)

[Claims] 1. A radiating fin having a hole in a proper position; a nut portion provided on a printed wiring board corresponding to the hole; and a screw penetrating to the nut portion through the hole. A radiation fin mounting structure characterized in that