JPH1187586A - Cooling structure for multi-chip module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cooling performance, by constituting a structure where a heat-generating part is in direct contact with a working medium. SOLUTION: Heat generated by operation of a semiconductor device 1 is transmitted to a surface of an LSI case 1. Since a liquid-like working medium 8 is led by a pillar wick 10 onto the surface of the LSI case 2, the heat vaporizes the liquid-like working medium 8 and dissipate it as latent heat into a sealed space. The vaporized working medium 8 comes into contact with a heat dissipation block 5 while moving in the sealed space. Since the heat dissipation block 5 has been cooled by cooling liquid 7, vapor of the working medium 8 is liquefied to transmit the latent heat to the heat dissipation block 5. The heat is led through the heat dissipation block 5 and transmitted to the cooling liquid 7 and dissipated outside. The working medium 8 liquefied on the surface of the heat dissipation block 5 is absorbed in a tabular wick 9, moves from the tabular wick 9 by a capillary phenomenon to each pillar wick 10, is led to the surface of each LSI case 1, and re-absorbs heat to be vaporized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cooling structure for a multi-chip module, and more particularly to a cooling structure for a multi-chip module utilizing the principle of a heat pipe.

[0002]

2. Description of the Related Art A conventional cooling structure of a multichip module will be described in detail with reference to the drawings.

FIG. 3 is a perspective view showing an example of the related art. In the cooling structure of the multi-chip module shown in FIG. 3, a planar heat pipe 102 is attached so as to be in contact with a plurality of heat-generating components 104 mounted on a plurality of printed circuit boards 101 arranged in parallel. The received heat is received and radiated from the heat radiating portions 107 on both sides. Cooling plate 110
Are attached to the heat radiating portions 107 on both sides of each heat pipe 102, and the liquid 109 is caused to flow through the flow path 108 inside the cooling plate 110 to cool the heat radiating portions 107 so that the heat pipes 102 function (for example, see Japanese Unexamined Patent Publication No. 172286
Reference).

FIGS. 4A and 4B are a top view and a side view showing an example of use of the cooling structure shown in FIG. The printed circuit board 101 includes a heating component 103 having a relatively small heating value and a small size and a heating component 1 having a large heating value and a large size.
The heat-generating component 104 is cooled by a planar heat pipe 102, and the heat-generating component 103 is cooled by a cooling fan 105 as necessary.

In order to cool the heat generating component 104 by the heat pipe 102, the heat receiving portion 10 of the planar heat pipe 102 is cooled.
6 is closely attached to the plurality of heat generating components 104 by means such as screwing. The heat pipe 102 is formed longer than the printed circuit board 101, and both sides thereof protrude from both ends of the printed circuit board 101, and serve as a heat radiating section 107 for dissipating the heat received by the heat receiving section 106. Heat pipe 1
If the heat-generating component 02 is attached in close contact with the heat-generating component 104, the short-shaped heat-generating component 103 cannot contact the heat pipe 102. Therefore, the gap formed between the printed board 101 and the heat pipe 102 is
Is blown from a cooling fan 105 provided at the end of the heat generating component 103 to cool the heat generating component 103.

FIGS. 5A to 5C are cross-sectional views showing the internal structure of the heat pipe shown in FIG. FIG. 5 (a)
A fibrous wick 111 for transporting the liquid 109 obtained by condensing the gas 109b evaporated from the liquid 109 in the heat generating unit 106 in the heat radiating unit 107 to the heat generating unit 106 by capillary action is attached.

FIG. 5B is a plan view showing a flat metal heat radiator 10.
A fine channel 111b having a triangular cross section is provided inside 2b, and the working medium is sealed therein. The working medium gathers at the corners of the flow path 111b due to surface tension and is distributed in the length direction due to capillary force. The flow path 111b
The central portion of the gas passage serves as a passage for the evaporated gas.

FIG. 5C shows a plate-shaped metal heat radiator 10.
A fine channel 111c having a rectangular cross section is provided inside 2c, and the working medium is sealed therein. The working medium gathers at the corners of the flow path 111c due to surface tension and is distributed in the length direction due to capillary force. The flow path 111c
The central portion of the gas passage serves as a passage for the evaporated gas. The flow path forming member has a height of 0.5 mm and a width of 0.1 mm, and water is used as a working medium (for example, see JP-A-8-21523).

[0009]

The above-described conventional cooling structure for a multi-chip module has the following problems.
There are factors such as variations in height when mounting a large number of heat-generating components, flatness of the contact surface between the heat pipe and the heat-generating component, and other factors that deteriorate the thermal conductivity from the heat-generating component to the heat pipe. Filling (applying) the above space with silicon grease or the like that has a higher thermal conductivity than air existing in
Even if each heat generating component is individually pressed by a spring or the like, there is a drawback that a desired thermal conductivity cannot be obtained.

[0010]

According to a first aspect of the present invention, there is provided a cooling structure for a multi-chip module, comprising: a multi-chip module comprising a wiring board on which at least one heat-generating component is mounted; A flange, a heat-dissipating block attached to the wiring board via the flange so as to cover the heat-generating component, and forming a sealed space including the heat-generating component together with the wiring board; and a flat wick provided on the heat-dissipating block. And a cooling medium that flows through the coolant channel and cools the heat radiation block, and a working medium sealed in the closed space.

[0011] A cooling structure for a multi-chip module according to a second invention is the LSI case according to the first invention, wherein the heat-generating product has a semiconductor element incorporated therein.

According to a third aspect of the present invention, in the cooling structure for a multi-chip module according to the first aspect, the heat-generating product is a semiconductor element.

According to a fourth aspect of the present invention, in the cooling structure for a multi-chip module according to the first aspect, the cooling block is air-cooled.

According to a fifth aspect of the present invention, in the cooling structure for a multi-chip module according to the first aspect, the flat wick is provided on a surface facing the heat-generating component, and the column wick is connected to the flat wick and each of the flat wicks. It is provided between the heat generating components.

In a sixth aspect of the present invention, in the cooling structure for a multi-chip module according to the first aspect, the working medium is a perfluorocarbon liquid whose boiling point is adjusted.

[0016]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention. The cooling structure of the multi-chip module shown in FIG. 1 includes a multi-chip module including a wiring board 3 on which a plurality of LSI cases 2 each containing a semiconductor element 1 are mounted, a flange 4 fixed to the wiring board, and an LSI case. A heat dissipating block 5 attached to the wiring board 3 via the flange 4 so as to cover the LSI case 2 and forming an enclosed space enclosing the LSI case 2 together with the wiring board 3, a working medium 8 sealed in the enclosed space, The radiating block 5 includes a working medium flow path composed of a flat wick 9 and a columnar wick 10 provided in the radiating block 5 and a cooling medium flow path 6.
And a working medium 8 sealed in the closed space.

The flat wick 9 is provided on the surface facing the LSI case 2, and the column wick 10 is
And each LSI case 2. The cross-sectional shape of the columnar wick 10 may be any shape such as a circle, a square, or a star, and may be a shape in which a portion in contact with the flat wick 9 or the LSI case 2 is expanded.

Since the working medium 8 is in direct contact with the wiring board 3 and the LSI case 2, it is required to have non-corrosive and insulating properties, and a perfluorocarbon liquid whose boiling point is adjusted is desirable.

A gasket, an O-ring, a sealing material or the like may be used between the flange 4 and the heat radiating block 5 in order to enhance the sealing performance.

Next, the operation will be described. Semiconductor element 1
The heat generated by the operation of the device is transmitted to the surface of the LSI case 2. The surface of the LSI case 2 is a columnar wick 10
As a result, the liquid working medium 8 is guided, and this heat vaporizes the liquid working medium 8 and dissipates it as latent heat to the closed space.

The working medium 8, which has become steam, contacts the heat radiating block 5 while moving in the closed space. Since the heat radiating block 5 is cooled by the cooling liquid 7, the vapor of the working medium 8 liquefies and transmits latent heat to the heat radiating block 5. Heat is transmitted to the coolant 7 through the heat dissipation block 5 and is radiated to the outside.

The working medium 8 liquefied on the surface of the heat radiating block 5 is absorbed by the flat wick 9, moves from the flat wick 9 to the respective column wicks 10 by capillary action of the wick, and moves to the surface of each LSI case 2. Be guided.
The working medium 8 absorbs heat again on the surface of the LSI case 2 and evaporates. Thus, the heat generated in the semiconductor element 1 is transmitted, and the semiconductor element 1 is cooled.

FIG. 2 is a sectional view showing a second embodiment of the present invention. The cooling structure of the multi-chip module shown in FIG. 2 is such that the semiconductor element 1 is directly mounted on the wiring board 3 in a bare chip state, the liquid working medium 8 is in direct contact with the semiconductor element 1 by the columnar wick 10, and the heat dissipation block 5
Is dissipated into the atmosphere by the radiating fins 11,
It is the same as FIG.

[0025]

According to the cooling structure of the multi-chip module of the present invention, since the heat generated by the heat-generating component is directly transmitted to the working medium, since the heat-generating component is in direct contact with the working medium, the solid-state material between Since it is not necessary to use an elastic material having poor thermal resistance or poor heat conduction due to contact, there is an effect that cooling performance can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of the related art.

FIGS. 4A and 4B are a top view and a side view showing an example of use of the cooling structure shown in FIG. 3;

5 (a) to 5 (c) are sectional views showing the internal structure of the heat pipe shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 LSI case 3 Wiring board 4 Flange 5 Heat dissipation block 6 Refrigerant flow path 7 Coolant 8 Working medium 9 Flat wick 10 Column wick

Claims (6)

[Claims] 1. A multi-chip module comprising a wiring board on which at least one heat-generating component is mounted, a flange fixed to the wiring board, and the wiring board via a flange so as to cover the heat-generating component. A heat radiation block attached to the wiring board and forming a sealed space that includes the heat generating component, a working medium flow path including a flat wick and a columnar wick provided in the heat radiation block, and a refrigerant flow path. A cooling structure for a multi-chip module, comprising: a cooling liquid for cooling the heat dissipation block; and a working medium sealed in the closed space. 2. An LS in which the heat-generating product includes a semiconductor element.
The cooling structure for a multi-chip module according to claim 1, which is an I case. 3. The heat-generating product is a pair chip.
The cooling structure of the described multi-chip module. 4. The cooling structure for a multi-chip module according to claim 1, wherein said heat radiation block is air-cooled. 5. The flat wick is provided on a surface facing the heat generating component, and the columnar wick is provided between the flat wick and each of the heat generating components.
The cooling structure of the described multi-chip module. 6. The cooling structure for a multi-chip module according to claim 1, wherein said working medium is a perfluorocarbon liquid whose boiling point has been adjusted.