GB2167550A

GB2167550A - Cooling apparatus for semiconductor device

Info

Publication number: GB2167550A
Application number: GB8527627A
Authority: GB
Inventors: Mitsuru Fukushima; Nobuyuki Yamashita
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1984-11-08
Filing date: 1985-11-08
Publication date: 1986-05-29
Also published as: JPS61113265A; GB8527627D0

Abstract

A cooling apparatus for a semiconductor device 1 comprising a metallic block 2 to which the semiconductor device is attached, which can serve as a heat sink for the semiconductor device and which has at least one coolant receptacle 3A formed therein, at least one pipe 45 which is mounted on said metallic block and which has a space portion communicating with said coolant receptacle thereby forming a heat pipe, and means for cooling said pipe. <IMAGE>

Description

SPECIFICATION Cooling apparatus for semiconductor device or the like Background of the invention This invention relates to improvements in a cooling apparatus for a semiconductor device or the like.

Figs. 4 and 5 show the prior-art arrangement of an apparatus of this type which is illustrated in, for example, 'Meiden Johe' (published February 1984, p. 36). Fig. 4 is a front sectional view, while Fig. 5 is a side sectional view.

Referring to these figures, numeral 1 designates a semiconductor device such as thyristor or transistor, which has terminal portions 1A and 1B. Numeral 2 designates a metallic block which is disposed in close contact with the terminal portion 1B, and which is made of a metal of high thermal conductivity such as copper or aluminum in order to derive heat generated by the semiconductor element 1.

Symbols 3A, 3B and 3C denote a plurality of trenches which are formed in the block 2. Symbols 4A, 4B and 4C denote heat pipe devices for leading out the generated heat of the semiconductor device. Each heat pipe device has a well-known construction in which a liquid coolant 41 is contained within a sealed pipe 40. The coolant 41 is normally received on one end side 42 of the pipe 40, and this end side is inserted in the corresponding trench 3A, 3B or 3C of the block 2.

It is needless to say that, in this case, the outside diameter of the pipes 40 is set at a value close to the inside diameter of the trenches 3A, 3B and 3C.

In addition, radiating fins 44 are provided on the other end side 43 of each pipe 40. Numeral 5 indicates an air duct which is disposed so as to surround the other end portions 43 of the heat pipes 40, and numeral 6 a fan which feeds the air duct 5 with cold air. In such an arrangement, the heat generated by the semiconductor device 1 is transferred to the metallic block 2. Further, it is transferred via the walls of the trenches 3A, 3B and 3C to the one-end sides 42 of the heat pipes 40 and then to the coolant 41 contained therein.

As a result, the coolant 41 is boiled or vaporized into a gas, which moves upwardly as seen in Figs.

4 and 5, namely, to the other-end sides 43 of the pipes 40. Since the walls of the other-end sides 43 are cooled by the cooling air from the fan 6, the gaseous coolant having thus risen from below is subjected to heat exchange by the walls of the other end portions thereby to be condensed into a liquid, which flows back to the one-end sides 42 again along the walls of the pipes 40. In this case, the cooling effect can be increased further by forming the inner surfaces of the pipes 40 into roughened surfaces on both the one-end sides and the other-end sides. Although the cooling of the other-end sides 43 has been explained as the type employing the fan 6, cooling based on natural convection or radiation can be similarly utilized.

In the above manner, the heat exchange is effectuated to cool the semiconductor device 1. In the prior-art apparatus, however, the bore of the trench 3A, 3B or 3C of the metallic block 2 cannot be brought into perfect agreement with the outside diameter of the pipe 40, where the former is made larger than the latter, so that an air layer arises between the trench and the pipe. Due to an interior thermal conductivity, this air layer has exerted a very bad influence on the cooling characteristic of the semiconductor device. To the end of removing the air layer to improve the cooling characteristic, it has been tried to pour a material of high thermal conductivity such as solder into the space between the wall of the trench 3A, 3B or 3C and the oneend side 42 of the pipe 40.The trial, however, has not been practical because it is difficult to check if the solder is deposited on the whole surface of the one-end side 42 of the pipe 40.

Summary of the invention This invention has been made in order to cope with such problems, and has for its object to exclude the setup in which one end of a pipe is inserted in the trench of a block.

This invention consists in that each pipe is fixed to an outer surface of a metallic block, and that a sealed vessel as a heat pipe is constructed of the pipe and the trench of the block communicating therewith. A coolant (41) is received directly in the trenches (3A, 3B and 3C) of the metallic block, and the outer surfaces of the pipes are formed with fins for heat exchange.

Although the function of heat exchange is similar to that in the prior art, heat produced from a semiconductor device is transferred to the coolant directly from the metallic block in this invention, so that the cooling efficiency is remarkably enhanced.

Brief description of the drawings Figure 1 and 2 show an embodiment of this invention, in which Fig. 1 is a front sectional view and Fig. 2 is a side sectional view; Figure 3 is a front sectional view showing another embodiment of this invention; and Figures 4 and 5 show a prior-art apparatus, in which Fig. 4 is a front sectional view and Fig. 5 is a side sectional view.

In the drawings, the same symbols indicate identical or corresponding portions.

Preferred embodiments of the invention Now, an embodiment of this invention illustrated in Figs. 1 and 2 will be described. Fig. 1 shows a front sectional view, and Fig. 2 a side sectional view. Referring to these figures, symbols 3A, 3B and 3C denote trenches which are formed in a metallic block 2 and which form parts of sealed vessels as heat pipes. Numerals 45 designate pipes which form the other parts of the heat pipes. Each pipe 45 has its end part 45A remote from the metallic block 2 closed to define a space portion 45B, the outer surface of which is provided with a large number of fins 44. Shown at numerals 7 are joint adaptors which connect the pipes 45 with the trenches 3A, 3B and 3C.The upper ends of the joint adaptors 7 as viewed in the figures are equalized in diameter to the pipes 45, while the lower ends thereof are equalized in diameter to the trenches 3A, 3B and 3C. More specifically, in a case where the pipes 45 and the trenches 3A, 3B and 3C have equal diameters, they may be directly connected and fixed without interposing such joint adaptors. In contrast, in a case where they have unequal diameters as illustrated in the figures, they can be efficiently connected using the joint adaptors. As a result, it becomes possible to set the heat fluxes of a boiling section and a condensing section at will. Numeral 41 indicates a coolant which is received directly in the trenches 3A, 3B and 3C. The remaining construction is the same as in the prior-art apparatus, and shall not be repeatedly explained.

Heat generated by the semiconductor device 1 is transterred via the metallic block 2 and from the walls of the trenches 3A, 3B and 3C to the coolant 41, to boil or vaporize the coolant 41. Since the subsequent operations are similar to those of the prior art, they shall be omitted from the description.

Fig. 3 shows another embodiment of this invention. Wicks 8 having the capillary action are respectively stuck on the wall of the trench 3A of the metallic block 2 and the inner wall of the pipe 45.

A material having pores at a proper proportion, such as wire gauze or a sintered metal piece, is suitable as the wick.

Owing to the provision of such wicks, the rate of heat transfer in the boiling section can be further enhanced. Besides, since the coolant condensed and liquified in the space portions 45B of the pipes 45 are held in the wicks, the back flow of the liquid coolant into the boiling section is facilitated by the capillary pressures of the wicks.

While any of various materials such as water, ammonia, floriuato, fleon (trade name for gaseous fluorocarbon, manufactured by Daikin Industries), Dowtherm and alcohol is usable as the coolant, water is best from the point of the heat transport ability thereof. Since this invention is constructed as described above, it can perform cooling very efficiently. It should be noted that the object to be cooled is not restricted to the semiconductor device, but the invention is applicable to various electronic components and elements.

Claims

1. A cooling apparatus comprising a metallic block having a coolant receptacle formed therein and to which an article to be cooled is attached, a coolant contained in said coolant receptacle for absorbing heat generated from said article, a pipe having an interior portion in communication with said coolant receptacle, and connected with said metallic block so as to form with the said receptacle of the metallic block a heat pipe, and means for cooling said pipe.

2. A cooling apparatus comprising a metallic block having a coolant receiving section formed therein and to which an electric element of an article to be cooled is attached on the surface thereof, a coolant contained in said coolant receiving section for absorbing heat generated from said electric element, a pipe having a space portion communication with said coolant receiving section, and connected with said metallic block for forming a heat pipe together with the metallic block, and means for cooling said pipe.

3. A cooling apparatus as defined in claim 2, wherein said electric element is a semiconductor element.

4. A cooling apparatus as defined in claim 2 or 3 wherein wicks having proper pores are stuck to inner surfaces of said space portion of said pipe and said coolant receiving section of said metallic block.

5. A cooling apparatus as defined in claim 2, 3 or 4 wherein inner surfaces of said coolant receiving section and said pipe are rough so as to enhance the heat transfer efficiency thereof.

6. A cooling apparatus as defined in any preceding claim, wherein said means for cooling said pipe comprises fan.

7. A cooling apparatus as defined in any preceding claim wherein said means for cooling said pipe comprises fins formed on outer surfaces thereof.

8. A cooling apparatus as defined in any preceding claim, wherein said pipe is mounted on said metallic block through a joint adaptor, and said joint adaptor is in the shape of a tube one end of which is equal in diameter to said pipe and the other end of which is equal in diameter to said coolant receiving section.

9. Cooling apparatus substantially as herein described with reference to Figures 1 and 2 or Figure or Figure 3 of the accompanying drawings.