JPH04262563A - Heat dissipating structure for semiconductor device - Google Patents

Abstract

PURPOSE:To provide a heat dissipating structure of a semiconductor device having a high mounting height and excellent cooling performance in the structure of the device such as an LSI, etc., and particularly in a natural air cooling type heat dissipating structure. CONSTITUTION:A radiator 5 already provided in a semiconductor device 2 having fins 7 in multiple stages, a heat dissipating plate 20 in which a plurality of holes 21 are opened at positions corresponding to edges of the fins 7 and made of a metal plate sufficiently larger than the device 2 as seen in its planar shape, a pressing plate 31 pressurized on the upper surface of the plate 20, a plurality of legs 32 inserted into the holes 21 formed in an inverted L shape at the periphery of the plate 31, and clamping fittings 30 having pawls 33 to be engaged with the fins 7 of the radiator 5 formed at the lower parts of the legs 32, are provided. The plate 20 is placed on the upper surface of the fin 7 of the uppermost stage of the radiator 5, and the plate 20 is secured to the radiator 5 via the fittings 30.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation structure for semiconductor devices such as LSIs, and more particularly to a heat dissipation structure for natural air cooling.

As the speed of functions of semiconductor devices such as LSI increases, power consumption increases, and as a result, the amount of heat generated increases. Such semiconductor devices need to be cooled by dissipating the heat generated.

For this purpose, as shown in FIG. 4, a heat sink 5 is fixed in advance to the upper part of the package 3 of the semiconductor device 2, and the leads 4 are inserted into the through holes and soldered, or the leads 4 are placed on the mounting surface. A semiconductor device 2 is mounted on a printed wiring board 1 by soldering to pads.

The existing heat dissipation body 5 is made of a lightweight metal with high thermal conductivity such as aluminum, and has a plurality of disc-shaped fins 7 integrated with the support 6 at predetermined intervals in multiple stages. The lower surface of the fin is fixed to the upper surface of the package 3 of the semiconductor device 2.

A semiconductor device to which a heat radiator having a relatively small heat radiating area is fixed as described above has a heat radiating effect when applied to forced air cooling type electronic equipment.

[0006]

[Prior Art] The semiconductor device with the above-mentioned heat sink fixed to it is
As mentioned above, it is provided for forced cooling, so if it is applied to electronic equipment using a natural air cooling method, the heat dissipation capacity will be insufficient due to the small number of fins, and it will not be possible to sufficiently cool the semiconductor device. , the performance of the semiconductor device is not fully demonstrated.

Therefore, conventionally, as shown in FIG. 5, an auxiliary heat radiator 10 is mounted on the existing heat radiator 5 to cope with natural air cooling type electronic equipment. The auxiliary heat radiator 10 is
It has the same structure as the heat dissipation body 5 already installed in the semiconductor device 2, and is made of a lightweight metal with high thermal conductivity such as aluminum, and a plurality of disc-shaped fins 12 are installed at predetermined intervals on the supports 11.
This is a multi-stage integrated structure.

The auxiliary heat radiator 10 is constructed by placing the lower surface of the lowermost fin 12 on the upper surface of the uppermost fin 7 of the heat radiating element 5, and then inserting the elastic U-shaped connecting fitting 15 from the radial direction to ensure a tight fit. By fixing both fins together,
It is attached to the semiconductor device 2.

[0009]

However, when the auxiliary heat radiator is mounted on top of the existing heat radiator as described above, the mounting height becomes higher than that of other electrical components mounted on the printed wiring board.

[0010] As a result, it is necessary to increase the distance between printed wiring boards arranged in parallel, or to increase the distance from other parts installed in electronic devices, which impedes miniaturization of electronic devices. There was a problem.

The present invention was created in view of the above points, and an object of the present invention is to provide a heat dissipation structure for a semiconductor device that has a low mounting height and has excellent cooling performance.

0012

[Means for Solving the Problems] In order to achieve the above object, the present invention, as illustrated in FIG. A heat dissipation plate 20 made of a metal plate having holes 21 and sufficiently larger than the shape of the semiconductor device 2 in plan view is provided.

On the other hand, the heat dissipation plate 2 is made of an elastic metal plate.
0, and holes 21 of each heat dissipation plate 20 formed in an inverted L shape around the press plate part 31.
A fixing metal fitting 30 is provided, which has a plurality of legs 32 inserted into the radiator 5 and a claw 33 formed at the lower part of the leg 32 and hooked to the fin 7 of the existing heat sink 5.

Then, the heat sink 20 is placed on the upper surface of the uppermost fin 7 of the existing heat sink 5, and the heat sink 20 is fixed to the heat sink 5 by pressure using the fixing fittings 30. Moreover, as illustrated in FIG. 2, the lower surface of one heat sink 20-2 is
The structure is such that the fixing fittings 30 are used to press-bond each of the upper surfaces of the heat sinks 5 of the plurality of semiconductor devices 2 .

Alternatively, the shape of the heat sink 20-2 is made substantially equal to the shape of the printed wiring board 1 on which the semiconductor device 2 is mounted in plan view. Furthermore, as illustrated in FIG.
shall be fixed at

[0016]

According to the present invention, a heat radiating plate having a sufficiently large heat radiating area is in close contact with the upper surface of the existing heat radiating body. therefore,
Although the mounting height of the semiconductor device including the heat dissipation part is low, the heat dissipation capacity is increased and the semiconductor device can be sufficiently cooled when applied to electronic equipment using a natural air cooling method. Furthermore, since the mounting height is low, it does not become an obstacle to miniaturization of electronic devices.

Note that by making the shape of the heat dissipation plate almost equal to the plan view shape of the printed wiring board on which the semiconductor device is mounted and covering the entire surface of the printed wiring board, the heat dissipation area can be maximized. The heat sink also functions as a shield plate, and when applied to a device in which many printed wiring boards are arranged vertically in parallel on a shelf, the heat sink also functions to rectify the air rising between the printed wiring boards. .

Furthermore, by fixing the four corners of the heat sink to the printed wiring board via spacer posts, not only does the reliability of the adhesion with the existing heat sink become high, but also the parts mounted on the printed wiring board Also serves as a protective plate.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings. Note that the same reference numerals indicate the same objects throughout the figures.

FIG. 1 is a diagram of an embodiment of the present invention, (A) is a side sectional view, (B) is a plan view, FIG. 2 is a sectional view of another embodiment of the present invention, and FIG. 3 is a cross-sectional view of another embodiment of the present invention. FIG. 7 is a sectional view of still another embodiment. In FIG. 1, a heat sink 5 is fixed in advance to the upper part of a package 3 of a semiconductor device 2, and the leads 4 are inserted into through holes and soldered, or the leads 4 are soldered to pads on the mounting surface. 2 is mounted on the printed wiring board 1.

The existing heat radiator 5 is made of a lightweight metal with high thermal conductivity such as aluminum, and has a plurality of disk-shaped fins 7 integrated with the support 6 at predetermined intervals in multiple stages. The lower surface of the fin is fixed to the upper surface of the package 3 of the semiconductor device 2.

Reference numeral 20 denotes a thin rectangular heat dissipation plate made of a metal plate having high thermal conductivity and light weight, such as an aluminum plate, and its shape is sufficiently larger than the shape of the package 3 of the semiconductor device 2 in plan view. A plurality of (three in the figure) holes 21 are bored in the center of the heat sink 20 at positions corresponding to the edges of the fins 7 of the heat sink 5.

On the other hand, the reference numeral 30 denotes a fixing fitting formed by pressing an elastic metal plate, such as a thin stainless steel plate, into an inverted U shape when viewed from the side. The fixing fitting 30 has a disk-shaped pressing plate portion 3 smaller than the shape of the fin 7 in plan view which is crimped onto the upper surface of the heat dissipation plate 20.
1, and a plurality of (three in the figure) legs extending radially from the periphery of the pressing plate portion 31 and bent downward in an inverted L shape so as to be inserted into each hole 21 of the heat sink 20. 32
and the fins 7 of the existing heat sink 5 formed at the bottom of the legs 32.
It is comprised of a claw 33 which is dogleg-shaped in side view and which is engaged with.

To fix the heat sink 20 to the heat sink 5, the heat sink 20 is placed on the upper surface of the uppermost fin 7 of the existing heat sink 5. Then, attach the legs 32 of the fixing fittings 30 to the heat sink 20.
into the corresponding hole 21, and press the corner of the leg 32 with your hand as shown by arrow A to push the fixing metal fitting 30 downward. As a result, the claws 33 of each leg 32 engage with the lower surface of the edge of the fin of the heat sink 5 due to the elasticity of the leg.

Since the fixing fittings 30 are attached to the heat sink 5 as described above, the lower surface of the press plate portion 31 presses the upper surface of the heat sink 20 due to the repulsive force of the bent portion of the leg 32, and the heat sink 2
The heat sink 20 is fixed to the heat sink 5 with the lower surface of the heat sink 20 in close contact with the upper surface of the uppermost fin 7 of the heat sink 5.

Therefore, although the mounting height of the semiconductor device including the heat dissipation section is low, the heat dissipation capacity is increased and the semiconductor device 2 can be sufficiently cooled when applied to natural air cooling type electronic equipment. Further, the actual mounting height of the semiconductor device 2 is
Since the mounting height is almost equal to the height of the existing heat sink, it does not become an obstacle to miniaturization of electronic devices.

In FIG. 2, 20-2 is the semiconductor device 2.
It is a thin square plate-shaped heat dissipation plate that is approximately the same shape in plan view as the printed wiring board 1 on which is mounted. On the other hand, two semiconductor devices 2 are mounted on the printed wiring board 1, and a heat sink 5 is fixed to each of the semiconductor devices 2. The heights of the top surfaces of the uppermost fins 7 of these two heat sinks 5 are approximately equal.

The heat dissipation plate 20-2 is provided with holes into which fixing fittings 30 are inserted, corresponding to the respective semiconductor devices 2. Then, the heat sink plate 20 - 2 is fixed to the heat sink 5 of each semiconductor device 2 using the fixing fittings 30 with the lower surface of the heat sink 20 - 2 in contact with the top surface of the fins of the heat sink 5 .

As described above, since the heat sink 20-2 has a shape that is almost the same as that of the printed wiring board 1 in plan view, the heat sink area is maximized and not only the cooling capacity is large, but also the heat sink 20-2
0-2 also serves as a shield plate. Further, when applied to a device in which a large number of printed wiring boards are arranged vertically and parallel to each other on a shelf, the heat sink 20-2 also has the function of rectifying air rising between the printed wiring boards.

On the other hand, since the heat sink is flat, the shape of the fixing fittings is relatively simple, and one heat sink can be shared by a plurality of semiconductor devices, the cost is low.

In FIG. 3, the lower surface of a thin square plate-shaped heat sink 20-2, which is approximately the same shape in plan view as the printed wiring board 1 on which the semiconductor device 2 is mounted, is attached to a heat sink 5 by a fixing fitting 30.
is crimped onto the top surface of the fin.

Then, place the lower surfaces of the four corners of the heat sink 20-2 on the upper end surfaces of the spacing posts 40 set up at the four corners of the printed wiring board 1, and insert machine screws 41 into the heat sink from above the heat sink 20-2. 20-
It is inserted into the hole 2 and screwed into the screw hole of the spacing column 40.

As described above, by fixing the four corners of the printed wiring board 1 and the four corners of the heat sink 20-2 through the spacer posts 40, the heat sink can be easily fixed even if the heat sink 20-2 has a large shape. It never tilts. Therefore, the function of the fixing metal fittings 30 that press the heat sink 20-2 to the heat sink 5 can be ensured. Even if another object collides with the heat sink 20-2, the heat sink 20-2 will not come off or tilt, so the printed wiring board 1
It will also serve as a protection plate for the components mounted on the board.

[0034]

[Effects of the Invention] As explained above, the present invention provides the following excellent effects by attaching and detaching a heat sink with a large surface area to the top surface of a heat sink already installed in a semiconductor device. have

A semiconductor device for forced air cooling can be used for natural air cooling without modification, and the semiconductor device can be sufficiently cooled. Furthermore, since the mounting height of the semiconductor device including the heat dissipation section is low, it does not become an obstacle to miniaturization of electronic devices.

The heat sink has a flat plate shape, and the shape of the fixing metal fittings is also relatively simple and easy to attach and detach, and one heat sink can be used in common for a plurality of semiconductor devices. Therefore, the heat dissipation structure of the present invention is low cost.

On the other hand, by making the shape of the heat sink almost equal to the shape of the printed wiring board, not only the heat dissipation performance is further improved, but also the heat sink serves as a shield plate and the space between the printed wiring boards is increased. It has the function of rectifying the air, and also functions as a protection plate for components mounted on printed wiring boards.

[Brief explanation of the drawing]

[Figure 1] Diagram of an embodiment of the present invention (A) is a side sectional view (B) is a plan view

[Figure 2] Cross-sectional view of another embodiment of the present invention

[Figure 3]
A sectional view of still another embodiment of the present invention

[Figure 4] Side view of semiconductor device

[Figure 5] Side view of conventional example

[Explanation of symbols]

1 printed wiring board,
2 semiconductor device, 3 package, 5 heat sink, 6, 11 pillar,
7,12
Fin, 10 Auxiliary heat sink,
20, 20-2 Heat sink, 21 Hole, 30 Fixing fitting, 31
Pressing plate portion, 32
Legs, 40 spaced columns,

Claims (4)

[Claims] 1. A heat dissipation body (5) that is already installed in a semiconductor device 2 having multiple fins (7), and a metal plate that is sufficiently larger than the shape of the semiconductor device (2) in plan view; 7) a heat dissipation plate (20) with a plurality of holes (21) drilled at positions corresponding to the edges of the heat dissipation plate (20); and a press plate part (31) made of an elastic metal plate and press-fitted to the upper surface of the heat dissipation plate (20). , a plurality of legs (32) formed in an inverted L shape around the periphery of the pressing plate part (31) and inserted into each of the holes (21), and the heat sink formed at the lower part of the legs (32). (5) a fixing metal fitting (30) having a claw (33) that engages with the fin (7) of the heat sink (5); , and fix the heat sink (20) to the heat sink (
5) A heat dissipation structure for a semiconductor device, characterized in that it is configured to be crimped and fixed to. [Claim 2] The lower surface of one heat sink (20-2) is
The heat dissipation structure for a semiconductor device according to claim 1, wherein the heat dissipation structure for a semiconductor device is crimped to each of the upper surfaces of the heat dissipation bodies (5) of the plurality of semiconductor devices (2) by means of fixing fittings (30). 3. The shape of the heat sink (20-2) is substantially the same as the shape of the printed wiring board (1) on which the semiconductor device (2) is mounted in plan view. Heat dissipation structure of the semiconductor device described. [Claim 4] The heat sink (20-2) according to claim 3.
The four corners of the printed wiring board (1) are connected to the printed wiring board (1) via the spacing posts (40).
A heat dissipation structure for a semiconductor device, characterized in that the heat dissipation structure is fixed to a semiconductor device.