JPH073844B2 - Heat transfer device - Google Patents

Description

The present invention relates to a heat transfer device suitable for cooling a high heat density member such as an integrated circuit for an electronic computer.

[Conventional technology]

Immersing the integrated circuit chip in a coolant with a low boiling point,
A method is known in which the cooling liquid is boiled by the heat generated from the chips to cool the chips. As a method to promote this boiling cooling, the length of one side is 0.2 to 2
Small tunnel-shaped cavities of about mm are formed in multiple layers by crossing each other vertically and horizontally, and a large number of cavities arranged in a certain layer and cavities adjacent to the cavities are provided at intersections of the cavities. A heat transfer device provided with a porous heat transfer body connected to each other by openings is described by W. Nakayama. Heat sink studd hubbing enhanced boiling surface for cooling of microelectronic components (W.Nakayama, et al. “Hea
t SinkStuds Having Enhanced Boiling Surfaces for c
ooling of Microelectronic components ").

Since this heat transfer device has a very high boiling heat transfer coefficient, it is suitable for cooling a high heat density member such as an integrated circuit chip. However, when a plurality of chips mounted on a substrate are fitted with heat transfer devices of the same shape, no consideration has been given to a method of keeping the temperatures of the chips having different heat generation amounts uniform.

In addition, one of the boiling cooling devices for integrated circuit chips that has been conventionally proposed is to immerse a wiring board on which a large number of chips are mounted in an insulating liquid, and the heat generated from the chips causes vapor bubbles generated from the liquid to rise. Then, it reaches the condenser provided on the upper part of the wiring board, is condensed by this condenser and is reduced to the liquid in the lower part. However, in this method, when the heat values of the chips are different from each other, or even if the heat values are the same, the vapor bubbles generated from the chips mounted on the lower part of the wiring board affect the foaming from the chips mounted on the upper part. It was not possible to make the temperature of the chips uniform by changing the heat transfer performance. Examples of devices related to this type of device include Japanese Patent Publication No. 52-15358.

[Problems to be solved by the invention]

The above-mentioned prior art does not consider a method of keeping the temperature of a large number of chips mounted on a wiring board uniform regardless of the heat generation amount of each chip. Therefore, the temperature of each chip varies depending on the amount of heat generation, and the operating speed of the element cannot be made uniform. Therefore, in order to keep the temperature of each chip uniform,
Shape of heat transfer member attached to each chip (heat transfer function)
Had to be changed according to the calorific value.

The object of the present invention is to control the heat transfer performance of each chip without changing the shape of the heat transfer device, regardless of the heat generation amount of each heat generating element, and to set the temperature of each heat generating element to an optimum temperature which is set in advance. To hold in.

[Means for solving problems]

The above-mentioned purpose is to form a heat transfer element joined to a plurality of heat generating elements in the same shape, and cover the heat transfer surface with a covering member having an area corresponding to the heat generation amount of each heat generating element. Is achieved according to the amount of heat generation.

[Operation] Each heat transfer element joined to each heat generating element is changed in accordance with the amount of heat generation of the heat transfer area of each heat generating element so that each heat transfer element has the cooling capacity required for the set cooling temperature. Because it was formed into
The temperature of each heating element can be cooled to the set temperature regardless of the amount of heat generated by each heating element.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. In FIG. 2, reference numeral 1 is a wiring board on which an integrated circuit is assembled. On this board 1, a large number of semiconductor chips for integrated circuits are assembled as heating elements 2. A heat transfer member 3 for cooling the chip is attached to the back surface of the chip 2. The heat transfer body 3 is formed by laminating a plurality of fine tunnel members 31 each having a tunnel-shaped fine passage, which will be described later, and a cap 4 is placed on the tip of the heat transfer body 3.

The fine tunnel member 31 is shown in FIG. The fine fins 32, 33 of the fine tunnel member 31 are formed by providing grooves 34, 35 on both sides of the heat conductive thin plate in a direction intersecting with each other. The sum of the depths of the grooves 34, 35 is formed to be larger than the thickness of the thin plate, and therefore, at the intersection of the grooves 34, 35,
Cross openings 36 are formed to connect the grooves. The groove shape may be any shape such as a square, a circle, and a triangle. Further, the material is preferably a highly heat conductive material such as copper or aluminum. The fine tunnel member 31 is laminated in a plurality of layers and joined together and covered with a cap.
Shown in the figure. The grooves 34 and 35 shown in FIG. 3 form a tunnel-shaped cavity to form a vertical tunnel 41 and a horizontal tunnel 42, respectively, and the tunnels 41 and 42 are communicated with each other by a cross opening 36. 4 shows a cap.

FIG. 1 shows the entire structure of a heat transfer device for cooling a wiring board having a large number of mounted semiconductor chips 2 in the heat transfer body 3 having the above structure.

A large number of semiconductor chips 2 to which the heat transfer bodies 3 are attached are assembled to the wiring board 1. A plurality of substrates 1 on which the semiconductor chips are mounted are dipped and housed in a cooling liquid 6 filled in a container 5 side by side at appropriate intervals in the vertical direction. The cooling liquid 6 is an insulating liquid having a low boiling point. This liquid causes boiling at a relatively low temperature, and the semiconductor chip 2
If the heat flow from the is low, a temperature below the boiling point of the liquid is generated and normal convection occurs. A nuclear boiling point occurs when the heat flow reaches a temperature above the boiling point of the liquid. The bubbles evaporated on the fine tunnel wall of the fine tunnel member 31 (see FIG. 4) of the heat transfer body 3 escape to the outside through the vertical tunnel 41 in the vertical direction. Following the above action, the fine tunnel member 31
Liquid enters the tunnel member from the tunnel inlet opening on the outer surface of the
It is taken into 31. The liquid is supplied to the entire area inside the fine tunnel member 31 through the horizontal tunnel 42 that faces the horizontal direction and the opening 36 that connects the crossing tunnel. In addition, the horizontal tunnel 42 can hold some of the vapor generated at the wall, which acts as a nucleus for the next bubbling, causing bubbling to continue. Here, the relationship between the heat transfer body height, which is the total number of tunnels, that is, the number of stacked fine tunnel members 31, and the heat generation amount of the chip is as shown in FIG.
Experiments and calculations have shown that when the chip temperature is kept the same, the higher the height of the heat transfer body, that is, the larger the tunnel structure portion that contributes to heat transfer, the larger the amount of heat generation. Therefore, as shown in FIG. 2, even if the number of stacked layers is constant, by covering a part of the heat transfer body 3 with the cap 4, the vapor escape and the liquid introduction action described above are prevented, The same effect as when the number is small can be obtained. Also, the heat transfer performance can be arbitrarily controlled by changing the length lc of the cap 4 and adjusting the portion covering the heat transfer body.

All the heat transfer members 3 attached to the chip 2 have the same shape, and the cap 4 placed on the tip has a length corresponding to the amount of heat generated by the semiconductor chip 2.

Since the effective heat transfer area of the heat transfer body 3 is partially reduced by the cap 4, the heat transfer performance is changed depending on the size of the covering area, and the set temperature can be maintained even if the heat generation amount of the semiconductor chip 3 is different. it can. Therefore, according to the present embodiment, when chips having different heat generation amounts are mixed on the wiring board 1, a cap having a large length lc is attached to a heat transfer body of a chip having a small heat generation amount, and a cap of a chip having a large heat generation amount is transferred. By covering the heat element with a cap with a small length lc, the heat transfer performance can be controlled without changing the shape and dimensions of the microstructure of the heat transfer element.
The temperature of each chip can be cooled to the set optimum temperature, and the temperature of each chip can be kept substantially uniform. Furthermore, when manufacturing the heat transfer body, even if the heat transfer performance varies due to the dispersion of the performance of each heat transfer body itself and the interference of foam bubbles between the electric heat bodies related to the chip mounting position on the wiring board, It is possible to absorb the variation of. As the material of the cap 4, a material such as resin that is inexpensive and easy to process can be used as long as it is a material that is not attacked by the insulating liquid 6 in the container 5.

FIG. 6 shows another embodiment of the present invention. In this embodiment, the tape 14 is wound around a part of the heat transfer body 3 to reduce the function of the heat transfer body 3 and obtain the same effect as that of the above embodiment.

The heat transfer performance can be controlled by changing the width lt of the tape 14 according to the amount of heat generation. That is, the heat transfer performance can be controlled by wrapping a tape having a large width lt around the heat transfer body of the chip having a small heat generation amount and a tape having a small width lt around the heat transfer body of the chip having a large heat generation amount. . The tape does not necessarily have to be wrapped around the entire circumference of the heat transfer body 3, but by sticking it on a small part of the coated surface,
The heat transfer performance can be finely controlled. As shown in the figure, the winding position of the tape 14 on the heat transfer body 3 is changed by the adjacent heat transfer body, that is, as shown in the drawing, the winding position of the tape 14 is alternately arranged with the tip and the root. By doing so, the influence of foam bubbles at the tunnel entrance of the outer surface of the heat transfer body is not directly affected, and the bubbles discharged from the heat transfer body 3 do not directly enter the tunnel flow path of the heat transfer body 3 in the upper stage. West,
It is possible to average the mixing of the bubbles and the liquid in the rising bubble channel, and suppress the performance variation of the heat transfer body due to the influence of the rising bubbles. The tape 14 may be made of any material as long as it is not attacked by the insulating liquid.

Further, the coating of the heat transfer body 3 is not limited to the tape, but may be formed by filling the tunnel flow path with solder brazing, adhesive or the like so as to reduce the heat transfer action of the heat transfer surface. According to the present embodiment, in order to secure the heat transfer area corresponding to the heat generation amount of the semiconductor and the chip, as described above, the temperature of each semiconductor chip is made uniform by the extremely simple structure of the tape, the soldering solder, the adhesive and the like. Can be held at.

FIG. 7 shows still another embodiment. In this embodiment, the semiconductor chip is cooled by air cooling.

A fin member 23 is fixed to the upper wall surface of a large number of semiconductor chips 2 assembled on the substrate 1. Depending on the heat generation temperature of the chip 2, by covering a part between the fins of the fin member 23 with a cap 24 or a tape 25 as shown in FIG.
It blocks the flow path of the air that flows between the fins. The heat transfer performance can be controlled by changing the area that closes the fins with the cap 24 or the tape 25 according to the heat generation amount of the chip 2, and the temperature of the chip 2 can be kept uniform.
As a method of attaching the cap or tape to the fin member 23, a method of completely covering a part of the fin as shown in FIG. 7 and a method of covering a part of the fin member 23 as a whole as shown in FIG. Etc. can be taken.

〔The invention's effect〕

According to the present invention, even if heat generating elements having different heat generation amounts are mixedly mounted on the substrate, each heat transfer element joined to each heat generating element can perform heat transfer performance without changing its shape, dimensions, or the like. Can be made variable, and the cooling capacity can be controlled according to the amount of heat generation of each, so that the temperature of each heating element can be uniformly maintained at the set temperature.

[Brief description of drawings]

FIG. 1 is an overall side view of a heat transfer device showing an embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a perspective view of a fine tunnel member forming a heat transfer body. FIG. 4 is a partially enlarged perspective view of the heat transfer device of FIG. 1, FIG. 5 is a diagram showing the relationship between the height of the heat transfer body and the heat value of the chip, and FIG. 6 is another embodiment. FIG. 7 is an overall perspective view of a heat transfer device, FIG. 7 is a front view of a heat transfer device showing still another embodiment, and FIG. 8 is a front view of a heat transfer device showing yet another embodiment. 1 ... Substrate, 2 ... Heating element (semiconductor chip), 3 ... Heat transfer element,
4 ... Covering member (cap), 5 ... Container, 6 ... Coolant, 14
... covering member (tape), 23 ... fin member, 24 ... cap, 25 ... tape.

Claims (6)

[Claims] 1. A plurality of heating elements are mounted on a substrate, and a heat transfer element is attached to the heating element, and the heat transfer element is provided with intersecting fine tunnel channels or a large number of fins.
In a heat transfer device that cools a heating element by immersing each member in a cooling liquid or cooling air, the heating elements are formed in the same shape, and the heat transfer surface is covered with an area corresponding to the heating value of each heating element. A heat transfer device, characterized in that it is covered with a member, the heat transfer area of the heat transfer body is changed according to the amount of heat generation, and the temperature of each heat transfer body is cooled to a set temperature. 2. The heat transfer device according to claim 1, wherein the heat transfer body is formed by stacking a plurality of unit heat transfer bodies in a multi-layered manner and is juxtaposed in the vertical direction or the horizontal direction together with the heating element. 3. The heat transfer device according to claim 2, wherein the coating member is a cap-shaped coating. 4. The heat transfer device according to claim 2, wherein the covering member is a tape-like covering. 5. The heat transfer device according to claim 2, wherein the coating is solder braze or an adhesive, and the coating member fills the flow path of the heat transfer body. 6. The heat transfer device according to claim 4, wherein the coating portions of the heat transfer body are alternately arranged at the tip and the root of each heat transfer body.