JPH04186752A - Mounting structure of heat sink in electronic device - Google Patents

Abstract

PURPOSE:To enable dimensional error and thermal deformation to be absorbed by providing a penetration hole in a heat sink, passing a guide pin which is mounted to a reinforcement bar on a mother board through it, and then passing a coaxial spring through the guide pin and mounting a latch plate constraining an amount of contraction of a spring to the guide pin edge part. CONSTITUTION:By providing a proper clearance of a penetration hole which is provided at a guide pin 6 and a heat sink 4, a positional deviation in plane direction and thermal deformation can be released. Also, with a spring 7 which is mounted coaxially to the guide pin 6, the amount of contraction is confirmed by dimensions between the heat sink 4 and the latch plate 8 and a free length of the spring itself, and thus a proper spring force is generated and a heat sink 7 is pressed against a semiconductor package 3. Since the amount of thermal deformation is small enough as compared with an amount of contraction of the spring 7, this spring also absorbs thermal deformation in up and down directions, thus preventing damage. Also, when the spring 7 is installed in a penetration screw hole which is provided in the heat sink 4 and then it is rotated, a tip of the spring 7 projects from a bottom surface of the heat sink 4 and contacts a reinforcement structure 2 of a mother board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for mounting a heat sink such as a heat dissipation fin for cooling a heat generating element or the like of an electronic device.

[Conventional technology]

In the conventional device, as described in Japanese Utility Model Application Publication No. 63-64097, a heat conductive member is screwed to a plate through which a refrigerant passes, a concave surface is formed on the other surface of the heat conductive member, and a hardening heat conductive agent is applied thereto. It was characterized by being attached to a transformer etc. after filling.

Incidentally, related devices of this type include, for example, US Pat. No. 3,481,393.

[Problems to be solved by the invention]

The above conventional technology does not take into consideration the fixing of the plate through which the refrigerant passes, and therefore, due to the dimensional accuracy and installation error of the heat generating element (in this case the transformer), it is necessary to provide a wide space between the heat generating element and the heat conduction member. There were other problems, such as the risk of damaging the heating element etc. due to thermal deformation after installation. An object of the present invention is to provide a method for attaching a heat sink that absorbs these dimensional errors and thermal deformations.

Further, in the above-mentioned prior art, a plate for passing a refrigerant is further fixed to a component soldered to a printed circuit board, and there is also a problem in replacing one component.

Another object of the present invention is to improve the ease of replacing parts by making it possible to easily remove the heat sink.

[Means to solve the problem]

In order to absorb the above-mentioned dimensional errors and thermal deformation, a through hole is provided in the heat sink, a guide pin attached to a reinforcing rod on the motherboard is passed through this hole, and a coaxial spring is passed through the guide pin to reduce the amount of contraction of the spring. By attaching a stop plate that restrains the heat sink to the end of the guide pin, the heat sink is pressed against the semiconductor package by a spring force.

Also, for the purpose of easily removing the seat sink mentioned above,
A through-screw hole was provided in the heat sink.

[Effect]

The guide pin has the function of aligning the heat sink when attaching it to the semiconductor package, but by appropriately providing clearance between the guide pin and the through hole provided in the heat sink, it is possible to release misalignment in the plane direction and thermal deformation. Become. Further, the amount of contraction of the spring coaxially attached to the guide pin is determined by the dimension between the heat sink and the stop plate and the free length of the spring itself, thereby generating an appropriate spring force to press the heat sink against the semiconductor package.

The amount of thermal deformation is sufficiently small compared to the amount of spring contraction, so
This spring also absorbs thermal deformation in the vertical direction and prevents damage.

Furthermore, when a screw is attached to the through-screw hole provided in the heat sink and turned, the tip of the screw protrudes from the bottom of the heat sink and comes into contact with the reinforcement structure of the motherboard. When the screw is further turned, the contact point becomes a fulcrum, lifts the heat sink, and eventually overcomes the adhesive force of the thermally conductive grease between the semiconductor package and the heat sink, and the heat sink is peeled off from the semiconductor package.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

As shown in FIG. 1, a reinforcing structure 2 is attached on top of a motherboard 1, and a semiconductor package 3 is mounted thereon with the reinforcing structure 2 on both sides. A heat dissipation fin 4 serving as a heat sink is attached to the semiconductor package. FIG. 2 shows the cross section AA in FIG. 1. The semiconductor package 3 has I/O pins 31 and is electrically connected to a connector 11 attached to the motherboard. The heat dissipation fin 4 has a flat surface, and is attached to the flat surface of the semiconductor package 3 via thermally conductive grease 5 so as to be in close thermal contact therewith. However, since the thermally conductive grease is not an adhesive, although it makes it possible to later remove the heat dissipation fins 4, if no other pressing force is present, the effective adhesion of the heat dissipation fins 4 will be lost, and in the worst case In this case, it may fall off. One to several guide pins 6 are attached to the reinforcing structure on one side, and are passed through through holes 41 provided in the heat dissipation fins 4. A spring 7 having the same axis is passed through the guide pin 6, and the spring 7 is held down after restricting the amount of contraction by a flange 8. The flange 8 is attached to the guide pin 6 with screws 9. By providing a similar mechanism to all the guide pins attached to the reinforcing structure, the heat dissipation fins 4 are evenly pressed against the semiconductor package 3. Here, when attaching the guide pin 6 to the reinforcing structure 2, a threaded part was formed at the tip of the guide pin 6, and it was screwed into the inner thread formed on the reinforcing structure 2, but there is no particular need to separate these two parts. Therefore, fastening methods such as rivets and caulking may be used.

Next, a method for removing the heat radiation fins will be explained with reference to FIGS. 3 and 4.

FIG. 3 shows the state in which the flange 8 has been removed from the guide pin 6 and the spring 7 has been pulled out. In this state, the heat dissipating fins 4 appear to be adsorbed by the thermally conductive grease 5 and cannot be easily removed.

4th ri! I is the cross section BB in FIG. 1, and as shown, a female threaded hole 42 is provided near the midpoint of both sides of the heat dissipation fin. By screwing in the screw 10 here, the heat dissipation fin 4 is lifted from the point where its tip hits the reinforcing structure 2, eventually overcoming the adsorption force of the thermally conductive grease 5 and separating the semiconductor package 3 and the heat dissipation fin 4. 4 is separated.

〔Effect of the invention〕

According to the present invention, a heat sink for heat dissipation can be easily attached to a semiconductor package while ensuring good thermal adhesion using a flat surface and thermally conductive grease, and the heat sink for heat dissipation can be attached and detached without destroying the semiconductor package. Therefore, it is particularly effective for the mounting structure of a semiconductor package having an expensive multi-chip module structure including a plurality of semiconductors.

[Brief explanation of the drawing]

Fig. 1 is an overall view showing the semiconductor package and its surrounding motherboard, etc., Fig. 2 is a view showing section 8-A in Fig. 1,
3 is a section AA in FIG. 1 with the spring removed, and FIG. 4 is a section BB in FIG. 1 with the heat sink removed. 1...Motherboard, 11...Connector,
2... Reinforcement\Structure, 3... Semiconductor package, 3.
...I/O pin, 4.. Heat dissipation fin, 5.. Thermal conductive grease, 6.. Guide pin, 7.. Spring, 8.. Flange, 9.. Screw, 10.. Screw. Inferior I figure, □-, 2 Hayabusa 2 figure

Claims (3)

[Claims] 1. In a mounting structure in which a semiconductor package mounting one or more heat-generating semiconductors is mounted on a motherboard having a reinforcing structure, guide pins are placed on the reinforcing structure on the motherboard to attach the heat sink to the semiconductor package. By passing the provided through hole through the guide pin, passing the spring coaxially through the guide pin, and attaching a flange to the end of the guide pin to restrict the amount of contraction of the spring, the spring force of the spring can be used to A structure for mounting a heat sink in an electronic device, characterized in that the heat sink is brought into close contact with the semiconductor package. 2. In the structure, thermally conductive grease is applied between the heat sink and the semiconductor package, and the two are brought into close contact.
When a through-screw hole is provided in the Heat Mink and a screw is installed there, the tip of the screw will come into contact with the reinforcing structure on the motherboard, and as the screw is further screwed in, the point of contact between the reinforcing structure and the tip of the screw will be A heat sink mounting structure characterized in that the heat sink is removed from the semiconductor package by using it as a fulcrum and lifting the heat sink. 3. In claim 2, when a screw is attached to a through screw hole provided in the heat sink, the tip of the screw comes into contact with the semiconductor package, and as the screw is further screwed in, the point of contact between the semiconductor package and the tip of the screw is used as a fulcrum, A heat sink mounting structure characterized in that the heat sink can be removed from the semiconductor package by lifting it.