JP2001244668A - Heat sink fixing structure and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring a heat sink into contact with a radiating sheet disposed on an LSI, always in a fixed state. SOLUTION: A radiating sheet 6 is fixed on an LSI 4 mounted on a printed board 5. A positioning pin 8 of a flange 7 fixed to the printed board 5 is inserted in a pin hole 3, and a heat sink 1 is put on the LSI 4 via the radiating sheet 6. Height determining pins formed on both side surfaces of the heat sink 1 are made to engage with guide holes 11, and clamps 10 are fixed to the side surfaces of the flange 7 by using screws 12. Clearance 18 between both side surfaces of the heat sink 1 and the clamps 10 is made smaller than clearance 16 between the positioning pin 8 and the pin hole 3. Sufficient clearance 13 in the longitudinal direction is formed in a notch 17 through which the screw 12 of the clamp 10 is inserted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink fixing structure and method, and more particularly to an MCM (multi-ch).
The present invention relates to a structure and a method for fixing a heat sink that is in contact with a plurality of LSIs mounted on a printed circuit board of an IP module via a heat radiation sheet.

[0002]

2. Description of the Related Art Generally, in a heat dissipation structure of an MCM, LS is used.
Heat is radiated from I to the heat sink through the heat radiating sheet, but in order to keep the contact state between the heat sink and the heat radiating sheet constant, a spring is incorporated in the mounting portion of the MCM, and the heat sink is pressed against the LSI with a constant force by the spring. The compression strain of the heat radiating sheet was kept constant.

[0003]

However, the structure in which the heat sink is pressed against the LSI with a spring has the following problems.

[0004] The first problem is that a mechanical part for holding the spring is required in order to incorporate the spring, and the number of parts increases. Further, the structure becomes complicated, and miniaturization is difficult.

[0005] The second problem is that when vibration or impact is applied to the mounting portion of the MCM and a force exceeding the spring force is applied to the heat sink, the heat sink moves and the contact state between the heat sink and the heat radiation sheet changes. There was something to do.

The present invention provides an MCM that solves the above problems.
And the like.

[0007]

The heat sink fixing structure of the present invention comprises a substrate (5 in FIG. 1), an integrated circuit device (4 in FIG. 1) mounted on the substrate, and a flange fixed to the substrate. (7 in FIG. 1), a heat sink (1 in FIG. 1) in contact with the upper surface of the integrated circuit device via a heat dissipation sheet (6 in FIG. 1), and the substrate provided at a plurality of locations on the side surface of the heat sink. A plurality of height-determining pins (2 in FIG. 1) parallel to the guide holes (FIG. 1) into which the height-determining pins are fitted.
11), and a plurality of clamps (10 in FIG. 1) fixed to the side surface of the flange by fixing screws (12 in FIG. 1) screwed to the flange, wherein the height determining pin of the heat sink is provided. The length of the portion sandwiched between the two side surfaces provided with is smaller than the length between the side surfaces of the flange to which the corresponding clamp is fixed, and the opening through which the fixing screw of the clamp is inserted (17 in FIG. 1) ) Is characterized in that there is a margin in the direction perpendicular to the substrate with respect to the outer shape of the fixing screw.

The heat sink fixing structure of the present invention comprises a substrate (5 in FIG. 1), an integrated circuit device (4 in FIG. 1) mounted on the substrate, and a flange (FIG. 1) fixed to the substrate.
7) and a heat dissipation sheet (FIG. 1) on the upper surface of the integrated circuit device.
6) the heat sink (1 in FIG. 1) contacting via
A plurality of height determining pins (2 in FIG. 1) provided at a plurality of locations on the side surface of the heat sink and guide holes (11 in FIG. 1) into which the height determining pins are fitted are provided. A plurality of clamps (10 in FIG. 1) fixed to the side surface of the flange by fixing screws (12 in FIG. 1) screwed into the flange, and a pin hole (10 in FIG. 1) fixed to the flange and provided in the heat sink. A positioning pin (8 in FIG. 1) inserted in (1) 3) in a direction perpendicular to the substrate, wherein the side of the heat sink on which the height determining pin is provided is fixed to the clamp. The opening (17 in FIG. 1), which is located backward from the side surface of the flange and through which the fixing screw of the clamp is inserted, has a margin in the direction perpendicular to the substrate with respect to the outer shape of the fixing screw. .

In the above heat sink fixing structure, the substrate may be rectangular, the flange may be a frame shaped to cover only the peripheral edge of the substrate, and the heat sink may have a peripheral edge of a rectangular bottom face facing the flange. Two clamps are fixed to each of the opposite side surfaces of the flange, and two height determining pins are provided on two opposite side surfaces of the heat sink corresponding to the clamps. A plurality of circuit devices may be mounted.

According to the heat sink fixing method of the present invention, a heat radiation sheet (6 in FIG. 1) is placed on the upper surface of an integrated circuit device (4 in FIG. 1) mounted on a substrate (5 in FIG. 1). 1) is placed on the integrated circuit via the heat dissipation sheet, and a height determining pin (2 in FIG. 1) provided on the heat sink in a state where the heat sink is loaded so as to press the heat sink against the integrated circuit. 1) is fixed to a flange (7 in FIG. 1) having a guide hole (11 in FIG. 1) in which a guide hole (11 in FIG. 1) is provided.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG.
FIG. 3 is an exploded perspective view and an assembled perspective view of a heat sink fixing structure in the MCM according to the embodiment of the present invention. FIG. 3 is a sectional view taken along the line AA of FIG. 1, and FIG.
It is sectional drawing.

A heat radiation sheet 6 is mounted on the upper surface of the LSI 4 mounted on the printed circuit board 5. Metal flange 7 fixed to printed circuit board 5 with screws (not shown)
Two positioning pins 8 are planted on the upper surface of the heat sink 1, and the pins 8 are inserted through the pin holes 3 provided on the bottom surface of the heat sink 1, and the heat sink 1 is mounted on the LSI 4 via the heat radiation sheet 6.

The heat sink 1 has four horizontal height determining pins 2 on both sides, and the pins 2 are fitted into guide holes 11 of the clamp 10. The clamp 10 has two longitudinally long inverted U-shaped cuts 17 on the lower side in each case.
And is fixed to the side surface of the flange 7 by a screw 12 which is inserted through the cut 17 and is screwed into a tap 9 provided on the side surface of the flange 7. Accordingly, the heat sink 1 is held by the clamp 7 via the clamp 10 so that both sides do not move in the vertical direction.

As shown in FIG. 4, a clearance 16 is provided between the pin 8 and the pin hole 3. The width 14 between both side surfaces of the heat sink 1 is sufficiently shorter than the width 15 between both side surfaces of the flange 7, and the clearance 16 is smaller than the difference between the width 14 and the width 15. The position accuracy with respect to the heat sink 1 and the position accuracy of the pin holes 3 with respect to both sides of the heat sink 1 are sufficiently determined so that even when a dimensional tolerance at the time of manufacturing occurs in the width 14 of the heat sink 1 or the like, the clamp 10 can be used.
Is fixed to the flange 7, a clearance 18 is secured between the side surface of the clamp 10 and the side surface of the flange 7, that is, the clamp 10, so that the clamp 10 does not contact the side surface of the heat sink 1.

As shown in FIG. 4, a sufficient clearance 13 is provided in the notch 17 of the clamp 10 in the longitudinal direction with respect to the shaft diameter of the screw 12. Even if the thickness changes, the clamp 10 can be securely fixed to the flange 7 with the screw 12. The bottom surface of the heat sink 1 is flat, and the height of the flange 7 is set sufficiently lower than the height of the heat radiation sheet 6 placed on the upper surface of the LSI 4.

Next, the flow of heat from the LSI 4 as a heating element to the heat sink 1 will be described. The heat sink 1 is a metal material having good heat conduction efficiency, for example, Al. The heat radiating sheet 6 is a material having high heat conduction efficiency, and the heat generated in the LSI 4 is transmitted to the heat sink 1 through the heat radiating sheet 6 and is radiated to the outside air by a plurality of fins of the heat sink 1.

Next, a method of assembling the heat sink fixing structure according to the present embodiment will be described with reference to the drawings.

As shown in FIG. 1, an LS is
I4 is mounted, the flange 7 is fixed, and the heat sink 1 is mounted on the MCM on which the heat radiation sheet 6 is mounted on the LSI 4 by inserting the positioning pins 8 into the pin holes 3. With the bottom surface of the heat sink 1 in contact with the heat radiating sheet 6, a constant load is applied to the heat sink 1 so as to press the heat sink 1 toward the LSI 4 so that the contact between the heat sink 1 and the LSI 4 and the heat radiating sheet 6 is constant. And then
The clamp 10 is fixed to the side surface of the flange 7 with the screw 12 by fitting the height determining pin 2 into the guide hole 11. The height determining pin 2 is freely slidable in the guide hole 11, and even if the screw 12 is tightened, the clearance 18 is secured between the clamp 10 and the heat sink 1. And the heat sink 1 is not distorted.

After the clamp 10 is fixed by the screw 12, the heat sink 1 is fixed to the flange 7 in the height direction because the pin 2 is fitted into the guide hole 11, and the contact state between the heat sink 1 and the heat radiation sheet 6 is maintained. It does not change.

The portion of the clamp 10 through which the screw 12 is inserted may be a slot instead of a cut.

The bottom surface of the heat sink 1 is
If a step is provided so that the contact portion with the heat radiating sheet 6 projects downward from the contact portion with the heat radiating sheet 6, the heat radiating sheet 6
There is no need to be higher.

[0022]

The first effect is that the structure is simple and the work of fixing the heat sink on the integrated circuit device is easy. For this reason, the assembling work does not require skill, and the assembling can be performed in a short time.

The second effect is that even when vibration or shock occurs, the distance between the heat sink and the integrated circuit device is reduced.
That is to ensure that it is kept constant. Therefore, the contact state between the heat sink and the integrated circuit device and the heat radiation sheet is always kept constant.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a heat sink fixing structure according to an embodiment of the present invention.

FIG. 2 is a perspective view of the heat sink fixing structure shown in FIG. 1 after assembly.

FIG. 3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along the line BB of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat sink 2 Height determining pin 3 Pin hole 4 LSI 5 Printed circuit board 6 Heat dissipation sheet 7 Flange 8 Positioning pin 9 Tap 10 Clamp 11 Guide hole 17 Notch

Claims (6)

[Claims] 1. A substrate, an integrated circuit device mounted on the substrate, a flange fixed to the substrate, a heat sink in contact with an upper surface of the integrated circuit device via a heat radiation sheet, and a side surface of the heat sink. A plurality of height determining pins provided at a plurality of locations parallel to the substrate, and guide holes into which the height determining pins are fitted are provided, and are fixed to side surfaces of the flange by fixing screws screwed to the flange. A plurality of clamps, wherein the length of the portion of the heat sink sandwiched between the two side surfaces provided with the height determining pin is smaller than the length between the side surfaces of the flange to which the corresponding clamp is fixed, A heat sink fixing structure, wherein an opening of the clamp through which the fixing screw is inserted has a margin in a direction perpendicular to the substrate with respect to an outer shape of the fixing screw. 2. A substrate, an integrated circuit device mounted on the substrate, a flange fixed to the substrate, a heat sink in contact with an upper surface of the integrated circuit device via a heat dissipation sheet, and a side surface of the heat sink. A plurality of height determining pins provided at a plurality of locations parallel to the substrate, and guide holes into which the height determining pins are fitted are provided, and are fixed to side surfaces of the flange by fixing screws screwed to the flange. Including a plurality of clamps and positioning pins fixed to the flange and inserted in pin holes provided in the heat sink in a direction perpendicular to the substrate, the side surfaces of the heat sink on which the height determining pins are provided correspond. The clamp is retracted from a side surface of the flange to which the clamp is fixed, and an opening of the clamp through which the fixing screw is inserted corresponds to an outer shape of the fixing screw. A heat sink fixing structure characterized by having a margin in a direction perpendicular to the substrate. 3. The substrate according to claim 1, wherein the substrate has a rectangular shape, the flange has a frame shape covering only a peripheral edge of the substrate, and the heat sink has a peripheral edge of a rectangular bottom face facing the flange. 3. The heat sink fixing structure according to 2. 4. The apparatus according to claim 1, wherein two of the clamps are fixed to each of the opposite side surfaces of the flange, and two of the height determining pins are provided on the opposite side surfaces of the heat sink corresponding to the clamps. The heat sink fixing structure according to claim 3, wherein 5. The heat sink fixing structure according to claim 1, wherein a plurality of said integrated circuit devices are mounted on said substrate. 6. A heat radiation sheet is placed on an upper surface of an integrated circuit device mounted on a substrate, a heat sink is placed on the integrated circuit via the heat radiation sheet, and the heat sink is loaded so as to be pressed against the integrated circuit. A heat sink fixing method, comprising: fixing a clamp provided with a guide hole provided on the heat sink, the guide hole being fitted with a height determining pin parallel to the substrate, to a flange fixed to the substrate.