JPH07161886A - Structure for mounting heat sink of flat plate type semiconductor package - Google Patents

Abstract

PURPOSE:To reliably and replaceably mount a heat sink on a flat plate type semiconductor package to be surface-mounted on printed wiring board. CONSTITUTION:A flat plate type semiconductor package 2 is mounted on a printed wiring board 1, and rod-shaped spacers 4 are arranged. The height (length) of this spacer 4 is determined so that it is lower than the upper surface of the mounted semiconductor package 2. A heat sink 3 has a shape and dimension that project from the upper surface of the semiconductor package, and four countersunk holes 3a are drilled in that projecting section, corresponding to the arranged position. To fix the heat sink 3 to the upper surface of the semiconductor package 2 by contacting it, the heat sink 3 is placed on the upper surface of the semiconductor package 2 and screw-tightened against the spacer 4 with a countersunk heat screw 5. This structure makes it possible to cope with the situation where the printed wiring board 1 and the semiconductor package 2 are not accurately parallel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink for a flat plate type semiconductor package, in which a heat sink is attached to a flat plate type semiconductor package mounted on a printed wiring board by a fixing method which is more reliable, easier and replaceable than an adhesive method. Regarding mounting structure.

[0002]

2. Description of the Related Art A conventional example will be described with reference to the side view of FIG. In FIG. 5, the printed wiring board 1
In order to dissipate the heat generated by the semiconductor package 2 when the heat-generating flat-plate semiconductor package 2 is mounted, a large number of round bar-shaped projections are erected and distributed substantially on the surface of the material with a large heat transfer coefficient. A radiator (generally called a heat sink) 11 having a large surface area is fixed by an adhesive 12 or a double-sided adhesive tape (not shown).

[0003]

In the conventional example, (1) the workability of the adhesive or the double-sided pressure-sensitive adhesive tape is poor, and it takes several hours to surely harden, (2) the ambient temperature is relatively high. When used continuously for a long time under the conditions, as shown in FIG. 6, in particular, the printed wiring board 1 and the semiconductor package 2 are
When the is installed vertically, the adhesive part 12 or the adhesive part may loosen, causing the radiator 11 to slip off. (3) When it becomes necessary to replace the semiconductor package, remove the radiator for replacement. There are drawbacks such as difficult to do.

The problem to be solved by the present invention is to solve the above problems of the prior art, and to replace the heat sink securely, easily and with respect to the flat plate type semiconductor package surface-mounted on the printed wiring board. (EN) It is possible to provide a radiator mounting structure for a flat plate type semiconductor package that can be mounted.

[0005]

According to a first aspect of the present invention, there is provided a heat sink mounting structure for a flat plate semiconductor package, wherein the heat sink is mounted on a flat plate semiconductor package mounted on a printed wiring board. A spacer standing upright and having a length shorter than the surface distance between the surface of the printed wiring board and the surface on which the radiator of the mounted semiconductor package is to be mounted; Heat radiation mounted on the surface of the semiconductor package so as to protrude therefrom. And a fastener for removably fixing the container to the spacer.

According to a second aspect of the present invention, there is provided a heat sink mounting structure for a flat-plate semiconductor package, wherein the heat sink is mounted on a flat-plate semiconductor package mounted on a printed wiring board. A pedestal that receives on the surface opposite to the surface to be mounted, and the surface on which the radiator of the mounted semiconductor package at that time should be attached protrudes upward; heat dissipation that is mounted on the surface of the semiconductor package so that it protrudes A fastener for detachably fixing the container to the pedestal.

[0007]

In the radiator mounting structure for a flat-plate semiconductor package according to claim 1, the length of the spacers provided upright on the printed wiring board is such that the surface of the mounted semiconductor package on which the radiator is mounted and the printed wiring board are mounted. Shorter than face-to-face distance. Therefore, when the radiator is mounted on the surface of the semiconductor package so as to protrude therefrom, a gap is created between the lower surface of the radiator and the upper surface of the spacer. Therefore, in this state, when the radiator is fixed to the spacer with a detachable fastener such as a screw, the surface contact between the radiator and the semiconductor package is surely made.

In the radiator mounting structure of the flat-plate semiconductor package according to the second aspect, when the semiconductor package is received by the pedestal, the surface of the semiconductor package on which the radiator is to be mounted is located above the upper surface of the pedestal. It becomes a protruding shape. Therefore, when the radiator is mounted on the surface of the semiconductor package so as to protrude from the surface of the semiconductor package, a gap is created between the lower surface of the radiator and the upper surface of the pedestal. Therefore, in this state, when the radiator is fixed to the pedestal with a detachable fastener, for example, a screw, surface contact between the radiator and the semiconductor package is surely performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of a radiator mounting structure for a flat plate type semiconductor package according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view of the first embodiment, and FIG.
Is also a plan view thereof. In FIG. 1, a flat plate type semiconductor package 2 is mounted on a printed wiring board 1. On the other hand, the printed wiring board 1 is provided with four rod-shaped spacers 4 by means of small screws from the rear side thereof, which are not labeled.
Is erected. The height (length) of the spacer 4 is determined so as to be lower than the upper surface of the mounted semiconductor package 2. In other words, there is a gap between the upper surface of the spacer 4 and the upper surface of the mounted semiconductor package 2.
The radiator 3 has a shape and a size protruding from the surface of the semiconductor package 2, and four plate chamfered holes 3a are formed in the protruding portion so as to correspond to the standing positions of the spacers 4.

Now, in order to contact the heat sink 3 to the upper surface of the semiconductor package 2 and fix it, the heat sink 3 is placed on the upper surface of the semiconductor package 2, and the heat is dissipated by using the countersunk screw 5 which is a fastener in the invention. The container 3 is screwed to the spacer 4. In order to deal with the case where the parallelism between the printed wiring board 1 and the semiconductor package 2 is not accurate, as described above, a gap is provided between the upper surface of the spacer 4 and the upper surface of the mounted semiconductor package 2. The heat sink 3 is provided with a countersink hole 3a, and a countersunk machine screw 5 is used.
That is, although the dish portion of the dish machine screw 5 and the dish portion of the dish burr hole 3a are slightly biased, this bias can absorb an error in parallelism. The first embodiment can completely eliminate the drawbacks of the conventional example.

FIG. 3 is a side view of the second embodiment. The second embodiment is a system in which even when the parallelism between the printed wiring board 1 and the mounted semiconductor package 2 is not accurately obtained, it is possible to completely deal with the problem. A plate-shaped pedestal 7 is provided below the semiconductor package 2 to receive it. Cradle 7
As shown in the side sectional view of FIG. 4 (a) and the plan view of FIG. 4 (b), is a rectangular ring-shaped plate member, through which the lead of the semiconductor package 2 penetrates the central hollow portion. Then, the receiving surface 7a that receives the semiconductor package 2 at its peripheral portion is formed in a spot facing shape. At this time, the height dimension of the pedestal 7 is determined so that the upper surface of the semiconductor package 2 projects from the upper surface of the pedestal 7. The radiator 6 is the same as the radiator 3 except that the four fixing holes are counterbored holes 6a.

To contact the heat sink 6 to the upper surface of the semiconductor package 2 and fix the heat sink 6, the heat sink 6 is placed on the upper surface of the semiconductor package 2, and the heat sink 6 is supported by a pan head screw 8. Fasten with screws. As mentioned earlier,
In the second embodiment, there is no problem even if the parallelism between the printed wiring board 1 and the mounted semiconductor package 2 is not always accurate. The reason is that the fastening is performed between the pedestal 7 and the radiator 6, and there is a gap between the upper surface of the pedestal 7 and the upper surface of the semiconductor package 2, that is, the lower surface of the radiator 6. . Therefore, as the fastener, the pan head machine screw 8 is used in place of the countersunk machine screw 5 in the first embodiment, and the radiator 6 is correspondingly provided with the counterbore hole 6a.

[0013]

According to the radiator mounting structure of the flat type semiconductor package according to the first or second aspect of the invention, the radiator is fixed to the spacer or the pedestal with a fastener such as a screw. The surface contact between the semiconductor package and the semiconductor package is ensured. As a result, the fastening work can be performed easily and quickly, and even if the radiator and the semiconductor package are used at a relatively high temperature for a long time, the fixing between the radiator and the semiconductor package is reliably maintained, and the heat dissipation is also favorably maintained. Further, the semiconductor package can be easily replaced.

[Brief description of drawings]

FIG. 1 is a side view of a first embodiment according to the present invention.

FIG. 2 is a plan view of the first embodiment.

FIG. 3 is a side view of a second embodiment according to the present invention.

FIG. 4 is a side sectional view of the pedestal of the second embodiment, and FIG.

FIG. 5 is a side view of a conventional example.

FIG. 6 is a side view of a conventional example when mounted vertically.

[Explanation of symbols]

 1 printed wiring board 2 semiconductor package 3 radiator 3a countersunk hole 4 spacer 5 countersunk screw 6 radiator 6a counterbore hole 7 pedestal 7a receiving surface 8 pan head screw

Claims (2)

[Claims] 1. A structure in which a radiator is attached to a flat plate type semiconductor package mounted on a printed wiring board, the radiator being provided upright on the printed wiring board, and the surface of the printed wiring board and the radiator of the mounted semiconductor package being attached. A spacer having a length shorter than the surface distance from the surface to be formed; and a fastener for removably fixing the radiator mounted on the surface of the semiconductor package so as to protrude therefrom. Characteristic plate semiconductor package radiator mounting structure. 2. A structure in which a radiator is mounted on a flat plate type semiconductor package mounted on a printed wiring board, wherein the mounted semiconductor package is received on a surface opposite to the surface on which the radiator is to be mounted, and at that time. A pedestal whose surface on which the radiator of the mounted semiconductor package is to be attached protrudes upward; and a fastening for removably fixing the radiator mounted on the surface of the semiconductor package so as to protrude from the pedestal A radiator mounting structure for a flat plate type semiconductor package, characterized by comprising: