JPS63228650A - Cooling device for heating element - Google Patents

Abstract

PURPOSE:To make it possible to perform parallel cooling and to make an LSI package thin and compact, by conducting heat from heat generating elements to low-melting-point alloy through substrates, fusing the low-melting-point alloy, keeping the temperature of the low-melting-point alloy at a constant temperature as a whole, and effectively radiating the heat through heat radiating fins. CONSTITUTION:A plurality of LSI chips 3, which are heat generating elements, are mounted on one surface of each of two substrates 1. A space 7 is formed at each outer end of a heat conducting container 5. Indium alloy 9 is sealed in the container as low-melting-point alloy. Heat radiating fins 11 are attached to the outer surface of each end part 5a of the heat conducting container 5 by bonding and the like. The heat radiating fins 11 are arranged in parallel so that they are laterally deviated from a plurality of the LSI chips 3 in this constitution. The heat from the LSI chips 3 is laterally conducted through the liquified indium alloy 9 with less thermal resistance. The heat is efficiently radiated through the heat radiating fins 11, which are arranged in parallel with respect to the LSI chips 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) The present invention relates to a cooling device for a heat generating element used for cooling a package of a large computer, for example.

(Prior art) As a conventional cooling device for a heat generating element of this type, for example, a fourth cooling device is used.
There are some as shown in Fig. 5.

FIGS. 4 and 5 show, for example, the LS of a large computer.
This is an example of application to an I package, and in the one shown in FIG. 5, a fin 105 is attached to an LSI chip 103 as a heating element mounted on a substrate 101 via an adhesive. Furthermore, in the one shown in FIG. 6, a plurality of LSI chips 103 are mounted on one side of a base plate 101, and a fin 105 is attached to the other side with an adhesive.

By the way, the heat dissipation characteristics of such a cooling device are as follows:
It is no exaggeration to say that it is determined by the heat dissipation area of 5.
In order to effectively utilize the heat dissipation surface of the fins 105, it is important to reduce the thermal resistance from the heat generation surface to the heat dissipation surface.

However, as described above, in the structure in which the fins 105 are attached via an adhesive, some distortion of the surface of the substrate 101 or the LSI chip 103 due to the adhesion of the fins 105 must be taken into account, and the adhesive may be slightly removed. It is meant to be applied to the eyes.

For this reason, the thermal resistance in the lateral direction along the surface of the substrate 101 increases, so the fins 105 must be arranged vertically with respect to the LSI chip 103 as shown in FIGS. It has become impossible to perform parallel cooling by shifting or extending the positions, making it impossible to reduce the thickness and size of LSI packages.

(Problems to be Solved by the Invention) As described above, in the conventional device, since the fins are attached via an adhesive, parallel cooling is not possible.

Therefore, an object of the present invention is to provide a cooling device for heat generating elements that can perform parallel cooling.

[Structure of the Invention (Means for Solving the Problems)] In order to solve the above problems, the present invention forms a heat conductive container in which a heating element is mounted on one side and a low melting point alloy is sealed on the other side of the substrate. , this heat conductive container is provided with radiation fins.

(Function) Heat from the heating element is transferred directly or indirectly to the low melting point alloy through the substrate. The temperature of the substrate is increased to the melting point of the low melting point alloy, and at the melting point the temperature is held constant for a period of time until the low melting point alloy becomes completely liquid. After that, the temperature of the low melting point alloy increases further and is maintained at a constant temperature overall,
Heat is effectively radiated from the heat radiation fins.

(Example) This invention will be described in detail below.

FIG. 1 is a sectional view of an embodiment of the present invention. 2
A plurality of LSI chips 3, which are heating elements, are mounted on one surface of the substrate 1. This LSI chip 3 is configured as a high-speed switching element, etc., and generates heat from electrons with transient characteristics.

A heat conductive container 5 is formed between the other surfaces of each of the substrates 1 . The heat conductive container 5 is formed of a metal plate and is thin, with an end portion 5a protruding further than the substrate 1 in the lateral direction. Furthermore, a space 7 is formed at the outer end of the heat conductive container 5, and an indium alloy 9 as a low melting point alloy is sealed inside. The low melting point alloy can also be a bismuth alloy or the like.

A radiation fin 11 is provided on the outer surface of the end portion 5a of the heat conductive container 5.
are attached by adhesive or the like, and the heat dissipation fins 11 are arranged in parallel with the plurality of LSI chips 3 with offsets in the lateral direction.

Furthermore, a plurality of through holes 13 are provided in the heat conductive container 5 at locations facing the substrate 1 and the heat radiation fins 11, so that a portion of the substrate 1 and the heat radiation fins 11 also serves as a part of the heat conductive container 5. ing. The through hole 13 facing the substrate 1 is
Furthermore, it corresponds to the position of the LSI chip 3.

Next, the effect will be explained.

Heat generated by the LSI chip 3 is transmitted from the substrate 1 to the indium alloy 9 via the heat conductive container 5. When the substrate 1 reaches the melting point of the indium alloy 9, the indium alloy 9 changes from solid to liquid. During the phase change of the indium alloy 9 from solid to liquid, the temperature is maintained at a constant temperature for a certain period of time as shown in FIG. 2, and when the indium alloy 9 becomes completely liquid, the temperature further increases.

In addition, indium alloy 9 becomes somewhat 11 when it changes from fixed to liquid.
! ! l1ffl, but this expansion is absorbed by the space 7 formed at the outer end of the heat conductive container 5.

In this way, the heat generated by the SI chip 3 is transferred laterally through the liquid indium alloy 9 with low thermal resistance, and from the heat dissipation fins 11 arranged in parallel to the LSI chip 3. Heat is dissipated efficiently. Furthermore, heat from the LSI chip 3 is emitted unsteadily, but since the heat is temporarily stored in the indium alloy 9, sudden and local temperature rises can be avoided, steady heat dissipation can be expected, and the substrate The temperature distribution also becomes uniform.

Furthermore, in this embodiment, since the through hole 13 is provided in the heat conductive container 5, even if the contact surfaces of the substrate 1 and the radiation fins 11 are distorted, the indium alloy 9 that has become a liquid can come into direct contact with it, which is different from the conventional method. Thermal resistance is significantly lower than when the heat dissipation fins are bonded using grease.

FIG. 3 shows a third embodiment of the present invention, in which a through hole 13 in a heat conductive container 15 in FIG.
This is done so that no .

In this embodiment, the indium alloy 9 cannot be in direct contact with the substrate 1 or the radiation fins 11, but the LSI deep 3
As in the embodiment shown in FIG. 1, the heat generated is transferred laterally through the indium alloy 9 with a small thermal resistance, and is efficiently radiated from the radiation fins 11.

(Effects of the Invention) As is clear from the above, according to the configuration of the present invention, the heat generated by the heating element melts the low melting point alloy, the temperature of the low melting point alloy is kept constant throughout, and the heat is radiated from the heat radiating fins. be carried out efficiently. Therefore, the heat dissipation fins can be arranged in parallel to the heat generating element, and cooling can be performed in parallel, allowing the device to be made smaller and thinner.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of one embodiment of the present invention, Fig. 2 is an explanatory diagram of phase change of an indium alloy, Fig. 3 is a cross-sectional view of another embodiment, and Figs. 4 and 5 are conventional examples. FIG. 1...Substrate 3...LSr chip (heating element)
5.15...Heat conductive container 9...Indium alloy (low melting point alloy) 11...Radiating fin

Claims (3)

[Claims] (1) A cooling device for a heat-generating element, characterized in that a heat-generating element is mounted on one side of a substrate, a heat-conductive container filled with a low-melting-point alloy is formed on the other side, and a heat-radiating fin is provided on the heat-conductive container. (2) A cooling device for a heat generating element according to claim 10, wherein a part of the substrate also serves as a part of the heat conductive container. (3) A portion of the fin also serves as a portion of the heat conductive container.
A cooling device for a heat generating element as described in 2.