JP2000091482A - Cooler for semiconductor element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooler for semiconductor element having higher performance and using water which is gentle to the environment as a refrigerant. SOLUTION: Thin hollow flat plate 1 of copper having closed opposite ends comprises a boiling section 4, having outer wall being fixed with a semiconductor element 2 while encapsulating refrigerant, i.e., water, in the hollow section thereof, a condensing section 6 which is fixed with heat dissipating fins 5 to the outer wall thereof, and a coupling section 7 for separating the boiling section 4 from the condensing section 6. Heat generated from the semiconductor element 2 is dissipated through the evaporation of the refrigerant at the boiling section 4 and condensation of the refrigerant at the condensing section 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling portion in which a semiconductor element is mounted on an outer wall, a hollow inside is filled with a refrigerant, and the other end is closed by communicating with a hollow flow path of the boiling portion. The present invention relates to a semiconductor device cooler that includes a condensing section and radiates heat loss of a semiconductor element by boiling vaporization of refrigerant in a boiling section and condensing and liquefaction of refrigerant vapor in a condensing section, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Boiling coolers have conventionally been used as coolers for semiconductor devices. This boiling cooler is made of aluminum, and generally contains perfluorocarbon as a refrigerant inside.

With the recent increase in global environmental protection, perfluorocarbons, which are alternative fluorocarbons, have become substances subject to emission control.

[0004] Therefore, it is desired to use water having the same cooling performance as perfluorocarbon and no problem of environmental destruction as a refrigerant.

However, if water is used as a refrigerant for the boiling cooler, the water corrodes aluminum and generates hydrogen.
The cooling performance of the boiling cooler is significantly reduced. Therefore, water cannot be used as a refrigerant in the conventional boiling cooler.

A heat-bipe type cooler has been conventionally used as a cooler for semiconductor devices, like a boiling cooler. The heat pipe is made of copper and can use water as a refrigerant, but does not have high cooling performance as described below.

Hereinafter, the structure and operation of the conventional heat pipe type cooler will be described with reference to FIG. 11A is a front view, and FIG. 11B is a cross-sectional view taken along line AA of FIG. In FIGS. 11A and 11B, the heat pipe type cooler has a heat pipe 21 in which the inside is hollow and a small amount of water is sealed as a coolant 3 is embedded in a copper block 22. In addition, a large number of radiating fins 5 are attached to the upper part of the heat pipe 21 to enhance the radiating performance. The semiconductor element 2 is mounted on the outer wall surface of the copper block 22.

In the heat pipe type cooler thus configured, the heat loss of the semiconductor element 2 is conducted through the copper block and transmitted to the heat pipe. Under conditions that the temperature of the boiling heat transfer surface that is the inner wall surface of the heat pipe 21 and the temperature of the water that is in contact with the boiling surface are sufficient to form a vapor phase,
Bubble nuclei are generated from the bubbling point of the boiling heat transfer surface, grow into bubbles 9, separate from the boiling heat transfer surface 8, and move from the boiling heat transfer surface 12 to the refrigerant 3.
The heat loss is transmitted to the water.

The detached bubbles 9 rise to the liquid surface by buoyancy and turn into vapor to move to the condenser 6, and the heat loss is carried to the condenser 6. The heat loss transferred to the condenser 6 is
The heat is radiated by the cooling air 11 passing through the space.

On the other hand, the cycle in which the steam 10 is cooled and condensed and condensed on the condensing heat transfer surface to become the condensed liquid 13 and returns to the boiling section 4 is repeated. As described above, the semiconductor element 2 is cooled.

[0011]

In the conventional heat pipe type cooler described above, water can be used as the refrigerant 3, but it has the following problems.

1) Since the areas of the boiling heat transfer surface 8 and the condensation heat transfer surface are small, the boiling heat transfer surface 8 and the refrigerant 3 and the condensation heat transfer surface 12
The temperature difference between the steam and the steam 10 is large.

2) The vapor 10 and the condensate 13 interfere with each other in the boiling section 4 and the condensing section 6 to cause uneven return of the liquid.
Of the refrigerant 3 in the chamber. This results in low heat transport capability.

3) Since the boiling heat transfer surface 8 is a flat surface, the firing point density on the boiling heat transfer surface 8 is low, and the generation and stabilization of the bubbles 9 cannot be promoted and the boiling heat transfer coefficient is small.

Accordingly, the temperature difference between the outer wall surface of the heat pipe 21 and the cooling air 11 decreases as the temperature difference between the boiling heat transfer surface 8 and the refrigerant 3 and between the condensation heat transfer surface 12 and the steam 10 increases. In addition, the size of the radiation fins 5 increases, and the outer shape of the cooler also increases. Dry-out due to the depletion of the refrigerant occurs at a relatively low heat flux, the heat transport ability is small, and it is impossible to cope with an increase in heat loss of the semiconductor element 2. In addition, there is a problem that the temperature difference between the semiconductor wires 2 mounted on the upper and lower sides is large and the electrical characteristics between the elements 2 are different.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device cooler which uses environmentally friendly water as a refrigerant and has higher performance, and a method of manufacturing the same. Specifically, (1) A cooler using environmentally friendly water as a refrigerant is provided.

(2) The heat radiation fins are downsized to provide a smaller cooler.

(3) To provide a cooler capable of coping with an increase in heat loss of a semiconductor element, that is, a large capacity and a high speed.

(4) To provide a cooler capable of minimizing a temperature difference between semiconductor elements and minimizing a difference in electrical characteristics between the elements.

[0020]

According to a first aspect of the present invention, there is provided a cooler for a semiconductor device, comprising: a thin plate having a copper closed end at both ends and a hollow inside; The thin flat plate separates a boiling portion in which a semiconductor element is mounted on an outer wall and water is sealed in a hollow portion as a refrigerant, a condensing portion in which a radiation fin is mounted on the outer wall, and a boiling portion and a condensing portion. It is constituted by a connecting portion.

According to the first aspect of the present invention, not only water can be sealed as a refrigerant, but also the boiling heat transfer surface and the condensation heat transfer surface are large because the areas of the boiling heat transfer surface and the condensation heat transfer surface are large. Temperature difference between the steam and the steam can be reduced. Further, since water as a refrigerant is sealed up to an upper portion than a range where the semiconductor element is mounted, a temperature difference between the semiconductor elements mounted above and below is small, and a difference in electrical characteristics between the elements is reduced. .

In order to achieve the above object, the invention according to claim 2 provides a liquid return flow path for returning the refrigerant liquefied in the condensing section to the boiling section by a refrigerant flow path forming member in the boiling section. The condensing part is provided with a member for forming a vapor flow path for guiding the vapor generated by the vaporization of the refrigerant to the condensing part, and the connecting part is provided with a partitioning member 3 for separating the boiling part and the condensing part. In addition, the refrigerant flow path forming members are joined to each other so that the refrigerant is circulated in one direction using natural circulation.

According to the invention corresponding to claim 2, in addition to the effect of the invention corresponding to claim 1, there is no interference between bubbles and condensate in the boiling portion, and no interference between vapor and condensate in the condensation portion. The return is smooth, and the depletion of the refrigerant in the boiling portion can be prevented. Thereby, the heat transport capacity is improved.

According to a third aspect of the present invention, an air-cooled heat sink is attached to the outer wall of the first or second aspect by brazing.

According to the third aspect of the present invention, not only water can be sealed as the refrigerant, but also the boiling heat transfer surface and the condensation heat transfer surface have a large area. Temperature difference between the steam and the steam can be reduced. Further, since water as a refrigerant is sealed up to an upper portion than a range where the semiconductor element is mounted, a temperature difference between the semiconductor elements mounted above and below is small, and a difference in electrical characteristics between the elements is reduced. .

According to a fourth aspect of the present invention, at least one air-cooled heat sink is attached to the outer wall of the condensing section by screws.

According to the fourth aspect of the present invention, in addition to the above-described operation, when the radiation fin is attached to the condenser by screwing, the radiation fin is divided into a plurality of parts and attached, so that the radiation fin and the condenser are separated. The contact thermal resistance existing between the outer wall surfaces of the first and second substrates can be reduced.

According to a fifth aspect of the present invention, a fin having a pitch and a height of 1.0 mm to 0.1 mm is provided on an inner wall surface of a condensing portion excluding a steam flow path. The semiconductor device cooler according to any one of claims 1 to 4, wherein the cooler is provided in the direction of gravity.

According to the fifth aspect of the invention, in addition to the above-described operation, the area of the condensation heat transfer surface can be increased, and the temperature difference between the condensation heat transfer surface and the steam can be reduced. In order to achieve the above object, the invention according to claim 6 is directed to an inner wall surface of the boiling portion excluding a liquid return flow path, which has a pitch of 0.12 mm to 1.2 mm and a width of 0.06 mm to 0.2 mm.
The semiconductor device according to claim 1, wherein fins having a height of 6 mm and a height of 0.1 mm to 1.0 mm are provided in a direction of gravity of the inner wall surface and a direction perpendicular to the direction of gravity. It is a cooler for.

According to the sixth aspect of the present invention, in addition to the above-described functions, the firing point density on the boiling heat transfer surface can be increased, the generation of bubbles can be promoted and stabilized, and the boiling heat transfer coefficient can be reduced. Can improve the boiling heat transfer coefficient, can reduce the temperature difference between the boiling heat transfer surface and the refrigerant, and can further reduce the temperature difference between the vertically mounted semiconductor elements. In addition, the difference in electrical characteristics between the elements is further reduced.

In order to achieve the above object, the invention according to claim 7 uses an antifreeze liquid as the liquid sealed in the boiling portion.

According to the seventh aspect of the present invention, in addition to the above-described operation, when the cooler of the present invention is used in a cold region, it is possible to prevent freezing of water as a refrigerant.

In order to achieve the above object, an invention according to claim 8 is that, after processing fine fins on the inner wall surface of the boiling portion, the member for forming the refrigerant flow passage is brazed, and the steam flow is connected to the connecting portion. After brazing the road forming member, further brazing the partition member after processing fine fins on the inner wall surface of the condensing portion, brazing the boiling portion and the connecting portion, and further brazing the connecting portion to the connecting portion. This is a method for manufacturing a semiconductor device cooler in which a closed vessel is formed by brazing a condensing portion, and a refrigerant is injected and vacuum degassed.

According to the invention corresponding to claim 8, the cooler can be easily manufactured.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> A first embodiment of the present invention will be described with reference to FIG. 1 is an overall view of a cooler for a semiconductor element, (a) is a front view, (b) is a cross-sectional view taken along line AA of (a), and (c) is a BB line of (a).
It is sectional drawing.

In FIGS. 1 (a), 1 (b) and 1 (c), a semiconductor device cooler is a thin flat plate whose both ends are closed with copper and whose inside is hollow, and a street thin flat plate is an outer wall. A boiling part 4 in which a semiconductor element 2 is mounted on the inside and water 3 is sealed as a refrigerant in a hollow part, a condenser part 6 in which a radiation fin 5 is mounted on an outer wall, and the boiling part 4 and the condenser part 6 are separated. It is composed of a connecting portion 7.

The radiation fins 5 are extrusion fins made of aluminum comb and are attached to the condenser 6 by brazing.

Further, the water 3 as a refrigerant is filled up to an upper portion of a region where the semiconductor element 2 is mounted.

In the semiconductor element cooler configured as shown in FIG. 1, the heat loss of the semiconductor element 2 is caused by the heat conduction inside the wall of the boiling portion 4 and the boiling heat transfer on the inner wall surface inside the boiling portion 4. Face 8
Transmitted to.

Under the condition that the temperature of the boiling heat transfer surface 8 and the temperature of the water 3 which is in contact with the boiling heat transfer surface 8 are sufficient to form a vapor phase, bubble nuclei are generated from the bubbling point of the boiling heat transfer surface 8 and the bubbles 9 The heat generation loss is transferred from the boiling heat transfer surface 8 to the water 3 serving as the refrigerant.

The detached air bubbles 9 buoyant on the liquid surface due to buoyancy, become swallowing air, and move to the condenser 6, and the heat loss is carried to the condenser 6. The heat loss transferred to the condenser 6 is
The heat is radiated by the cooling air 11 passing through the space.

On the other hand, the steam 10 is cooled and condensed heat transfer surface 12
The liquid is condensed and liquefied to form a condensed liquid 13, and a cycle of returning to the boiling portion 4 is repeated. As described above, the semiconductor element 2 is cooled.

At this time, since the boiling portion 4, the connecting portion 7, and the condensing portion 6 are made of copper, not only water 3 can be sealed as a refrigerant, but also the area of the boiling heat transfer surface 8 and the condensation heat transfer surface 14 is large. , Boiling heat transfer surface 8 and refrigerant and condensation heat transfer surface 14
Temperature difference between the steam and the steam 10 can be reduced.

Further, water 3 as a coolant is
Is sealed up to the upper part of the range in which the semiconductor elements 2 are mounted, so that the temperature difference between the semiconductor elements 2 mounted above and below is small, and the difference in electrical characteristics between the elements 2 is reduced.

In the semiconductor device cooler configured as shown in FIG. 1, 1) eco-friendly water 3 can be used as a refrigerant.

2) Boiling heat transfer surface 8, refrigerant and condensation heat transfer surface 1
The temperature difference between the steam 2 and the steam 101 is reduced, and the temperature difference between the outer wall surface 14 of the condensing part and the cooling air 11 can be increased accordingly, so that the radiation fins 5 can be downsized and the cooler can be downsized.

3) The difference in electrical characteristics between the semiconductor elements 2 can be reduced.

<Second Embodiment> FIG. 2 is an overall view of a semiconductor device cooler according to a second embodiment of the present invention. (A)
Is a front view, (b) is an AA sectional view of (a), and (c) is a BB sectional view of (a).

The heat radiation fins 5 are pin fins made of aluminum, and are attached to the condenser 6 by brazing. Others are the same as FIG.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a front sectional view of the semiconductor device cooler.

In FIG. 3, a refrigerant return flow path for returning the refrigerant liquefied in the condensing section 6 to the boiling section 4 is provided by the refrigerant flow path forming member 16 in the boiling section 4. A steam flow path 17 for guiding the vaporized steam 10 to the condensing section 6 is provided by a steam flow path forming member 18, and a connecting member 7 for separating the boiling section 4 and the condensing section 6 is provided. 19 is provided, and the partitioning member 19 is joined from the refrigerant flow path forming member 16 to circulate the refrigerant in one direction using natural circulation.

As a result, interference between the bubbles 9 and the condensed liquid 13 in the boiling section 4 and interference between the vapor 10 and the condensed liquid 13 in the condensing section 6 are eliminated, and the liquid returns smoothly. The exhaustion of the refrigerant can be prevented. Thereby, the heat transport capacity is improved.

<Fourth Embodiment> A fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is an overall view of the cooler for a semiconductor element, (a) is a front view, and (b) is a right side view. When the heat dissipating fins 5 are applied to the condensing section 6 by applying heat conduction grease by screwing, if one large fin 5 is attached by screws 20 at four points around the periphery, the attaching force at the central portion becomes small, so that the central portion has a small attaching force. The contact thermal resistance increases. By dividing and attaching the radiation fin 5 to a plurality of parts, the contact thermal resistance existing between the radiation fin 5 and the outer wall surface of the condensing part 6 can be reduced.

<Fifth Embodiment> A fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 shows fine fins 5
It is a perspective view of A. By providing fine fins having a pitch and height of 1.0 mm or less in the direction of gravity on the inner wall surface of the condenser 6 excluding the vapor flow path, the condensation heat transfer surface 12
The area of the heat transfer surface 12 can be increased.
Temperature difference between the steam and the steam 10 can be reduced.

<Sixth Embodiment> A sixth embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a perspective view of a fine fin 5B according to the sixth embodiment of the present invention.
FIG. 8 is a heat flux characteristic diagram of the degree of superheat of the heat transfer surface (temperature difference between the boiling heat transfer surface and the refrigerant) according to the sixth embodiment. FIG. 9 is a fin pitch-heat transfer surface superheat degree characteristic diagram of the sixth embodiment. FIG. 10 is a graph showing a heat flux-to-element maximum temperature difference characteristic of the sixth embodiment.

On the inner wall surface of the boiling part 4 except for the liquid return flow path,
Pitch is 0.12mm ~ 1.2mm) width is 0.06mm
Fine fins 5B having a height of 0.1 mm to 1.0 mm are provided in the direction of gravity of the inner wall surface and in a direction perpendicular to the direction of gravity.

With this configuration, the firing point density on the boiling heat transfer surface 8 can be increased, the generation of bubbles 9 can be promoted and stabilized, and the boiling heat transfer coefficient can be improved. As shown in FIG. 8, the temperature difference between the boiling heat transfer surface 8 and the refrigerant can be smaller than when the boiling heat transfer surface 8 is a smooth surface.

Further, as shown in FIG. 10, the temperature difference between the vertically mounted semiconductor elements 2 can be further reduced, and the difference in the electrical characteristics between the elements 2 is further reduced.

The pitch as shown in FIG. 5 is 0.12 mm to 1.2 m on the inner wall surface of the boiling portion except for the liquid return flow path.
m, width 0.06mm ~ 0.6mm, height 0.1mm
A fine fin of ~ 1.0 mm is provided in the direction of gravity,
The pitch as shown in FIG. 7 is 0.12 mm to 1.2 mm,
0.06mm to 0.6mm width and 0.1mm height
Even if the fine fins 5C of 1.0 mm are provided in the direction orthogonal to the direction of gravity, the same effect as in the embodiment of FIG. 6 can be obtained.

<Seventh Embodiment> A seventh embodiment of the present invention will be described. For example, ethylene glycol or ethanol is mixed with water, which is a refrigerant to be sealed in the boiling portion 4, in such a concentration as to prevent freezing. Thereby, when the cooler is used in a cold region, it is possible to prevent freezing of water as a refrigerant, and to prevent breakage due to freezing of the cooler.

<Eighth Embodiment> An eighth embodiment of the present invention will be described. The method for manufacturing the above-described semiconductor device cooler is performed as follows. After processing the fine fins on the inner wall surface of the boiling portion 4 described above, the coolant flow path forming member 16 of FIG. 3 is brazed, and the steam flow path forming member 18 of the connecting portion 7 is brazed. After processing the fine fins on the inner wall surface of the condensing part 16 and brazing the partition member 19, the brazing part 4 and the connecting part 7 are brazed, and the condensing part 6 is further brazed to the connecting part 7 and hermetically sealed. This is a manufacturing method in which a container is formed, water 3 as a refrigerant is injected, and then vacuum degassing is performed.

According to such a manufacturing method, the cooler of the present invention can be easily manufactured.

[0065]

According to the present invention, it is possible to provide an even higher performance cooler for a semiconductor device using environmentally friendly water as a refrigerant and a method for producing the same.

[Brief description of the drawings]

FIG. 1 is an overall view for explaining a first embodiment of a semiconductor element cooler of the present invention.

FIG. 2 is an overall view for explaining a second embodiment of a semiconductor device cooler of the present invention.

FIG. 3 is an overall view for explaining a third embodiment of a semiconductor device cooler of the present invention.

FIG. 4 is an overall view for explaining a fourth embodiment of a semiconductor device cooler of the present invention.

FIG. 5 is a perspective view illustrating a fin according to a fifth embodiment of the semiconductor device cooler of the present invention.

FIG. 6 is a perspective view illustrating a fin according to a sixth embodiment of the semiconductor device cooler of the present invention.

FIG. 7 is a perspective view illustrating a fin of a semiconductor device cooler according to a seventh embodiment of the present invention.

FIG. 8 is a diagram showing a heat transfer surface superheat degree and a heat flux characteristic for explaining a sixth embodiment of the semiconductor device cooler of the present invention.

FIG. 9 is a fin pitch and heat transfer surface superheat degree characteristic diagram for explaining a sixth embodiment of the semiconductor device cooler of the present invention.

FIG. 10 is a maximum temperature characteristic diagram between heat flux elements for describing a sixth embodiment of the cooler for a semiconductor element of the present invention.

FIG. 11 is a view for explaining a conventional heat pipe type cooler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hollow thin flat plate 2 ... Semiconductor element 3 ... Refrigerant 4 ... Boiling part 5 ... Radiating fin 6 ... Condensing part 7 ... Connecting part 8 ... Boiling heat transfer plate 9 ... Bubbles 10 ... Steam 11 ... Cooling 12 ... Condensing heat transfer surface 13: Condensed liquid 14: Condensing part outer wall surface

Claims (8)

[Claims] 1. A boiling section in which a material is copper and both ends are closed, and a thin flat plate having a hollow inside is provided. A semiconductor element is mounted on an outer wall of the thin flat plate and water is sealed in a hollow portion as a refrigerant. A condensing section having a radiation fin mounted on an outer wall; and a connecting section separating the boiling section and the condensing section, wherein the heat loss of the semiconductor element is reduced by the vaporization of the refrigerant in the boiling section by the vaporization of the refrigerant. A cooler for a semiconductor device, which radiates heat by condensing and liquefying refrigerant vapor in a section. 2. A refrigerant return flow path for returning the refrigerant liquefied in the condensing section to the boiling section by the refrigerant flow path forming member, and the refrigerant is generated in the condensing section by vaporization of the refrigerant. A steam flow path for guiding steam to the condensing section is provided by the steam flow path forming member, and the connecting section is further provided with a partitioning member for separating the boiling section and the condensing section,
Joining the partition member from the refrigerant flow path forming member,
2. The cooler for a semiconductor device according to claim 1, wherein the refrigerant is circulated in one direction using natural circulation. 3. The semiconductor device cooler according to claim 1, wherein an air-cooled heat sink is attached to an outer wall of the condensing section by brazing. 4. The cooler for a semiconductor device according to claim 1, wherein a plurality of air-cooled heat sinks are attached to an outer wall of the condensing section by screws. 5. A fin having a pitch and a height of 1.0 mm to 0.1 mm is provided on an inner wall surface of the condensing section excluding the vapor flow path in a gravity direction of the inner wall surface. 5. The cooler for a semiconductor element according to any one of 1 to 4. 6. The inner wall surface of the boiling portion excluding the liquid return flow path has a pitch of 0.12 mm to 1.2 mm and a width of 0.1 mm to 0.2 mm.
06mm-0.6mm, height 0.1mm-1.0mm
6. The semiconductor device cooler according to claim 1, wherein the fins are provided in a direction of gravity of the inner wall surface and a direction perpendicular to the direction of gravity. 7. The semiconductor device cooler according to claim 1, wherein the refrigerant filled in the boiling portion is an antifreeze. 8. After processing fine fins on the inner wall surface of the boiling portion, the coolant channel forming member is brazed, and the steam channel forming member is brazed to the connecting portion. After processing the fine fins on the wall surface and brazing the partitioning member, brazing the boiling portion and the connecting portion, further brazing the condensing portion to the connecting portion to form a closed container, Of manufacturing a cooler for semiconductor devices, which is subjected to vacuum degassing after injecting the gas.