JPS6136958A - Cooling structure of integrated circuit - Google Patents

Abstract

PURPOSE:To discharge heat from a semiconductor chip efficiently to the outside of a device by fixing and shaping a sliding pair formed by the inner surface of the hole of a thermal conducting plate and the side surface of a thermal conducting bar by a fixing agent after adjusting a fine clearance. CONSTITUTION:One end surfaces of thermal conducting bars 5 face integrated circuits 1 such as semiconductor chips mounted to a substrate 2 while interposing fine clearances 4. Clearances among the side surfaces of the thermal conducting bars 5 and the inner surfaces of holes bored to a thermal conducting plate 7 are filled with solder or a fixing agent 6 such as adhesives, thus mutually fastening the thermal conducting bars 5 and the thermal conducting plate 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a cooling structure for integrated circuits, particularly an L-type cooling structure capable of efficiently discharging heat generated from semiconductor chips to the outside of the device.
This invention relates to a cooling structure for an SI package.

Conventionally, a fan was used as a means to cool an IC mounted on a printed wiring board or a ceramic substrate, etc. It is common practice to blow cold air or air whose temperature has been lowered by 1 (I' f) using a cooling device.
The heat generated from C was eliminated. However, air is not necessarily the best refrigerant for carrying the heat dissipated from the IC to the outside of the device. The first reason is that the thermal resistance between the solid IC case or the heat sink and the air is large, and the temperature difference between them becomes large. The temperature of the air used as a refrigerant must be lowered, and the equipment required for this purpose is difficult.Take information processing equipment (hereinafter referred to as equipment) as an example, the temperature of the room in which it is installed must be lowered. In order to lower the temperature of the air, air conditioning equipment is required.The second reason for the disadvantage of using air as a refrigerant is that air has a small heat capacity, and a small amount of heat can raise the air temperature. In order to carry out a large amount of heat from inside the device, a large amount of air must be pumped into the device trap.However, in recent years, high-performance information processing devices have become highly integrated to increase their processing speed. Efforts have been made to improve the operating speed of ICs by increasing the power consumption, or to shorten the signal propagation delay time by increasing the density of packaging, resulting in an increase in the amount of heat generated and the heat density. In order to cool by conventional means, the room where the above device is installed requires air conditioning equipment with high cooling capacity.
7. Inside the device, a blower with high air volume and high discharge pressure is required to compensate for the decrease in air passages within the device due to the increase in packaging density and to exhaust a large amount of heat to the outside of the device. shall be. This not only makes the air blowing noise generated from the device abnormally large, but also causes the temperature to rise due to insufficient cooling of the IC, since it is extremely difficult to evenly distribute a large volume and high speed air flow inside the device. There was a drawback that this caused an increase in the temperature and also reduced the reliability of the device.

In order to solve these drawbacks, a cooling structure using liquid as a refrigerant as shown in FIG. 2 has been proposed.

FIG. 2 is a longitudinal cross-sectional view of a liquid cooling structure for a semiconductor chip, in which a piston 23 is pressed against a semiconductor chip 21 mounted on a substrate 20 by a compression spring 25 housed in a heat conduction plate 2G. , the heat generated in the chip 21 is transmitted from the piston 23 to the heat conduction plate 26 through a small gap 24 between the piston and the heat conduction plate 26, and the heat conduction plate 26 is further transferred from the refrigerant intake port 28. Injected and discharged 1] 29
It is configured to be cooled by the liquid refrigerant 27 discharged from. 22 is a connecting solder for attaching the semiconductor chip 21 to the substrate 20.

However, the cooling structure using liquid means shown in FIG. 2 also has the following serious drawbacks. The first problem is that since the semiconductor chip 21 and the metal piston 23 are in mechanical contact, the refrigerant 27 and the chip 21 cannot be electrically insulated. The refrigerant 27 is connected to the ground of the compressor and refrigerant delivery pump (both not shown) through a heat exchanger, etc., but this ground is very noisy, and unless an insulator other than water is used for the refrigerant, it is connected to the ground of the compressor and refrigerant delivery pump (both not shown). This is a very dangerous situation for the chip. Second, @mentioned piston 23
is pushed by the elastic force of the spring 25, so the piston 23 and the spring 25 produce ω6 == s”k/m
This creates a vibration system that mechanically affects the chip 21.

Here, ω0 is the resonance angular frequency, and the spring constant of the spring 25 is 1
m is the mass of the piston 23. In other words, if an external force such as an impact containing a resonance frequency component is applied to the device, the piston 2
3 may vibrate and destroy the semiconductor chip 21 that is in contact with it. Furthermore, the third reason is that pressure is constantly applied to the solder 22 for connection to the substrate 20, which causes creep deformation. This is particularly noticeable when low temperature solder is used.

An object of the present invention is to efficiently discharge heat generated from a semiconductor chip to the outside of a device without bringing any solid object into contact with the chip itself or the case of the chip, and without intervening air, which is inefficient as a refrigerant. It is an object of the present invention to provide a cooling structure that is capable of cooling, has low thermal resistance, and eliminates all of the above-mentioned conventional drawbacks.

For this purpose, the cooling structure based on the trap of the present invention is such that the first end face of the heat conduction rod is opposed to the integrated circuit mounted on the board with a small gap in between, and The sliding pair formed by the inner surface of the hole in the heat conduction plate drilled in the direction and the second side surface of the heat conduction rod is fixed with a bonding agent after the minute gap adjustment described above. Preferably, the heat conductive plate is cooled with a liquid refrigerant.

Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. 1st
Referring to the figure, one end surface of a heat conduction rod 5 faces an integrated circuit 1 such as a semiconductor chip mounted on a substrate 2Vc with a minute gap 4 in between, and the side surface of the heat conduction rod 5 and a heat conduction plate 7 The gap between the drilled hole and the inner surface is filled with a fixing agent 6 such as solder or adhesive, thereby identifying the heat conductive rod 5 and the heat conductive plate 7 with each other. but,
Since the integrated circuit 1 is attached to the substrate 2 by the connecting solder 3, the thickness of the solder varies greatly, and the range is usually over 100 μm, so the position of the face of the integrated circuit 1 facing the heat conductive rod 5 is accurate. It is not determined. Therefore, in the present invention, after the integrated circuit 1 is soldered to the substrate 2, an extremely thin film is placed on one side of the integrated circuit 1, and the substrate frame 8 is
and the heat conduction plate 7 are fixed with screws 9, and the heat conduction rod 5 is inserted and pressed onto the ultra-thin film on the integrated circuit 1 with a tamper, and the heat conduction rod 5 and After fixing the heat conduction plate 7, remove the screws 9 and separate the heat conduction plate 7 and the board frame 8 (-1. By removing the ultra-thin film and reassembling it, the integrated circuit 1 has the same minute gap as the thickness of the ultra-thin film. and the heat conductive rod 5.

Furthermore, in this embodiment, after setting minute gaps 4 for all integrated circuits by the method described above, a water cooling jacket 1o is fixed 12 on the upper surface of the heat conduction plate 7, and water is drained from the water inlet 11 into the water cooling jacket. By flowing water 13 to the opening 12 and cooling it, the integrated circuit 1 (7) has an electrically insulated structure with a small gap 4 in between, and is mechanically safe because it includes a vibration system. It is possible to realize a cooling structure with a low thermal resistance.Furthermore, by filling the minute gap 4 with an electrically insulating and thermally conductive optical filler, it is also possible to realize a cooling structure with an even lower thermal resistance.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an integrated circuit cooling structure according to an embodiment of the invention, and FIG. 2 is a vertical cross-sectional view of a conventional liquid cooling structure. ]... Integrated circuit, 2... Board, 3... Solder for connection, 4... Minute gap, 5... Heat conductive rod, 6... Adhesive, 7... Heat conductive plate,
8... Board frame. 9... Fixed screw, 10... Water cooling jacket 5] 3... Water.

Claims (2)

[Claims] (1) a substrate, an integrated circuit mounted on the substrate,
a heat conductive rod having a first surface facing the integrated circuit with a small gap therebetween and a second surface serving as an element of a sliding pair capable of sliding in a direction perpendicular to the substrate; a cooling plate having a heat conduction rod insertion hole that accommodates the rod and forms a sliding pair with the second surface of the heat conductive rod; and a fixing agent that is filled in the sliding pair part and fixes the part. A cooling structure characterized by having. (2) The cooling structure according to claim 1, wherein the cooling plate is provided with a liquid refrigerant jacket and is cooled by the liquid refrigerant.