JP3564350B2 - Heat sink fixing structure and method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat sink fixing structure and method, and more particularly to a structure and method for fixing a heat sink that is in contact with a plurality of LSIs mounted on a multi-chip module (MCM) printed circuit board via a heat dissipation sheet.
[0002]
[Prior art]
Generally, in the heat dissipating structure of the MCM, heat is dissipated from the LSI to the heat sink through the heat dissipating sheet. It was pressed against the LSI with force to keep the compression strain of the heat dissipation sheet constant.
[0003]
[Problems to be solved by the invention]
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 component for holding the spring is required to incorporate the spring, and the number of components increases. Further, the structure becomes complicated, and miniaturization is difficult.
[0005]
The second problem is that when vibrations and shocks are 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 were.
[0006]
The present invention provides a heat sink fixing structure in an MCM or the like that solves the above problems.
[0007]
[Means for Solving the Problems]
The heat sink fixing structure of the present invention includes a substrate (5 in FIG. 1), an integrated circuit device (4 in FIG. 1) mounted on the substrate, a flange (7 in FIG. 1) fixed to the substrate, A heat sink (1 in FIG. 1) that is in contact with the upper surface of the integrated circuit device via a heat radiation sheet (6 in FIG. 1); and a plurality of height determining pins provided at a plurality of locations on the side surface of the heat sink and parallel to the substrate. (2 in FIG. 1) and a guide hole (11 in FIG. 1) into which the height determining pin is fitted, and is fixed to the side surface of the flange by a fixing screw (12 in FIG. 1) screwed to the flange. And a plurality of clamps (10 in FIG. 1) of the heat sink, wherein the length of the portion of the heat sink between the two side surfaces on which the height determining pins are provided corresponds to the length of the flange to which the clamps are fixed. Less than the length between the sides, the clamp The opening fixing screw is inserted (17 in FIG. 1) is characterized in that there is room in the substrate and the direction perpendicular to the outer shape of the fixing screw.
[0008]
The heat sink fixing structure of the present invention includes a substrate (5 in FIG. 1), an integrated circuit device (4 in FIG. 1) mounted on the substrate, a flange (7 in FIG. 1) fixed to the substrate, A heat sink (1 in FIG. 1) that is in contact with the upper surface of the integrated circuit device via a heat radiation sheet (6 in FIG. 1); and a plurality of height determining pins provided at a plurality of locations on the side surface of the heat sink and parallel to the substrate. (2 in FIG. 1) and a guide hole (11 in FIG. 1) into which the height determining pin is fitted, and is fixed to the side surface of the flange by a fixing screw (12 in FIG. 1) screwed to the flange. A plurality of clamps (10 in FIG. 1) and positioning pins (8 in FIG. 1) fixed to the flange and inserted into pin holes (3 in FIG. 1) provided in the heat sink and perpendicular to the substrate. And determining the height of the heat sink. The side on which the clamp is provided is located retreated from the side of the flange to which the corresponding clamp is fixed, and the opening (17 in FIG. 1) of the clamp through which the fixing screw is inserted is formed in the outer shape of the fixing screw. On the other hand, there is a margin in a direction perpendicular to the substrate.
[0009]
In the above-described heat sink fixing structure, the substrate is rectangular, the flange is a frame-shaped frame that covers only the peripheral edge of the substrate, the heat sink causes the peripheral edge of the rectangular bottom surface to face the flange, and the clamp is Two of each of the height determining pins 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, and the integrated circuit device is provided on the substrate. A plurality may be mounted.
[0010]
According to the heat sink fixing method of the present invention, in the heat sink fixing structure described above, the heat radiation sheet (6 in FIG. 1) is provided on the upper surface of the integrated circuit device (4 in FIG. 1) mounted on the substrate (5 in FIG. 1). After placing the heat sink (1 in FIG. 1) on the integrated circuit through the heat dissipation sheet, the height determining pin (1) is inserted into the guide hole in a state where the heat sink is loaded so as to be pressed against the integrated circuit. The clamp (10 in FIG. 1) is fixed to the flange (7 in FIG. 1) by the fixing screw by fitting 2) in FIG.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 are an exploded perspective view and an assembled perspective view, respectively, of a heat sink fixing structure in an MCM according to an embodiment of the present invention. 3 is a sectional view taken along the line AA of FIG. 1, and FIG. 4 is a sectional view taken along the line BB of FIG.
[0012]
A heat radiation sheet 6 is attached to the upper surface of the LSI 4 mounted on the printed circuit board 5. Two positioning pins 8 are planted on the upper surface of a metal flange 7 fixed to the printed circuit board 5 with screws (not shown), and the pins 8 are inserted into the pin holes 3 provided on the bottom surface of the heat sink 1. Then, the heat sink 1 is placed on the LSI 4 via the heat radiation sheet 6.
[0013]
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 thereof, and the cuts 17 are inserted through the cuts 17 and screwed into the taps 9 provided on the side surfaces of the flanges 7. It is fixed to the side of. Therefore, the heat sink 1 is held by the flange 7 via the clamp 10 so that both sides do not move in the vertical direction.
[0014]
As shown in FIG. 4, a clearance 16 is provided between the pin 8 and the pin hole 3. The width 14 between both sides of the heat sink 1 is sufficiently shorter than the width 15 between both sides of the flange 7, and the clearance 16 is smaller than the difference between the width 14 and the width 15. The clamp 10 is fixed to the flange 7 even when a dimensional tolerance at the time of manufacture occurs in the width 14 of the heat sink 1 or the like by sufficiently obtaining the positional accuracy with respect to the heat sink 1 and the positional accuracy with respect to the both sides of the heat sink 1. Then, a clearance 18 is secured between the side surface of the clamp 10 and the side surface of the flange 7, that is, between the clamp 10, and the side surface of the clamp 10 and the side surface of the heat sink 1 do not come into contact with each other.
[0015]
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, and a load 16 is applied to the heat sink 1 to reduce the thickness of the heat radiation sheet 6. Even if it has changed, 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 sufficiently lower than the height of the heat radiation sheet 6 placed on the upper surface of the LSI 4.
[0016]
Next, the flow of heat from the LSI 4 serving 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 heat generated in the LSI 4 is transmitted to the heat sink 1 via the heat radiating sheet 6 and is radiated to the outside air by a plurality of fins of the heat sink 1.
[0017]
Next, a method of assembling the heat sink fixing structure according to the present embodiment will be described with reference to the drawings.
[0018]
As shown in FIG. 1, the LSI 4 is mounted on the printed circuit board 5, the flange 7 is fixed, and the positioning pin 8 is inserted into the pin hole 3 on the MCM on which the heat radiation sheet 6 is mounted on the LSI 4, and the heat sink 1 is mounted. Put on. 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 toward the LSI 4 so that the heat sink 1 and the LSI 4 and the heat radiating sheet 6 are brought into a constant state. 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, a clearance 18 is secured between the clamp 10 and the heat sink 1. And the heat sink 1 is not distorted.
[0019]
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 changes. There is no.
[0020]
The portion of the clamp 10 through which the screw 12 is inserted may be a slot instead of a cut.
[0021]
Further, if a step is provided so that the bottom surface of the heat sink 1 projects downward from the contact portion with the heat radiation sheet 6 from the contact portion with the flange 7, it is not necessary to make the heat radiation sheet 6 higher than the flange 7.
[0022]
【The invention's effect】
The first effect is that the structure is simple and the operation 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.
[0023]
A second effect is that the distance between the heat sink and the integrated circuit device is reliably kept constant even when vibration or impact occurs. For this reason, the contact state between the heat sink and the integrated circuit device and the heat dissipation 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]
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 Cut

Claims (6)

A substrate, an integrated circuit device mounted on the substrate, a flange fixed to the substrate, a heat sink in contact with a top surface of the integrated circuit device via a heat dissipation sheet, and a plurality of side surfaces of the heat sink. A plurality of height determining pins parallel to the substrate, and a plurality of clamps which are provided with guide holes into which the height determining pins are fitted and which are fixed to the side surfaces of the flange by fixing screws screwed to the flange. Wherein the length of the portion of the heat sink sandwiched between the two side surfaces on which the height determining pins are provided is smaller than the length between the side surfaces of the flange to which the corresponding clamp is fixed, and the fixing screw of the clamp is provided. A heat sink fixing structure, characterized in that an opening portion through which there is provided an allowance in a direction perpendicular to the substrate with respect to an outer shape of the fixing screw. A substrate, an integrated circuit device mounted on the substrate, a flange fixed to the substrate, a heat sink in contact with a top surface of the integrated circuit device via a heat dissipation sheet, and a plurality of side surfaces of the heat sink. A plurality of height determining pins parallel to the substrate, and a plurality of clamps which are provided on a guide hole into which the height determining pins are fitted and which are fixed to side surfaces of the flange by fixing screws screwed to the flange, A positioning pin that is fixed to the flange and is inserted into a pin hole provided in the heat sink and that is positioned perpendicular to the substrate, and the side of the heat sink on which the height determining pin is provided has the corresponding clamp fixed thereto. The clamp is set back from the side surface of the flange, and the opening through which the fixing screw of the clamp is inserted is formed with the substrate with respect to the outer shape of the fixing screw. Heatsink fixing structure, characterized in that there is a margin in a straight direction. 3. The heat sink according to claim 1, wherein the substrate is rectangular, the flange is a frame-shaped frame that covers only a peripheral edge of the substrate, and the heat sink has a peripheral edge of a rectangular bottom face facing the flange. 4. Fixed structure. 4. The clamp according to claim 3, 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. 3. The heat sink fixing structure according to 1. The heat sink fixing structure according to claim 1, wherein a plurality of the integrated circuit devices are mounted on the substrate. 6. The heat sink fixing structure according to claim 1, wherein the heat radiating sheet is mounted on an upper surface of the integrated circuit device mounted on the substrate, and the heat sink is mounted on the integrated circuit via the heat radiating sheet. Then, in a state where the heat sink is loaded so as to press the heat sink against the integrated circuit, the height positioning pin is fitted into the guide hole, and the clamp is fixed to the flange by the fixing screw. Fixed structure.

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