JPS62105496A - Heat transmission apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a heat transfer device suitable for boiling cooling of high heat generation density members such as computer integrated circuits, power semiconductors such as citristors, and electromotive density coils. There is a particular thing.

[Background of the invention]

US Pat. No. 3,706,127 describes a method for promoting evaporative cooling of integrated circuit chips. In this example, a large number of needle-shaped metals (dendrites) are formed by a metallurgical process on the back surface of a chip mounted on a wiring board. When an integrated circuit chip is immersed in a non-conducting liquid, dendrite aggregation can occur due to the heat generated by the integrated circuit chip.
．． ! It contains a large number of bubble-generating nuclei necessary to generate vapor bubbles of non-conductive fluid. Therefore, the heat generated by the integrated circuit chip can be quickly removed by boiling, and an increase in the temperature of the chip can be suppressed. However, since this surface structure is fine, it is effective when the heat negative 1r is small, but when the heat flux of the heating surface becomes large, steam generation becomes too active and the surface is covered with a vapor film. It has the disadvantage that it is prone to the so-called burnout phenomenon in which the surface temperature rises rapidly, and that the allowable amount of heat generation is small.

As another example, it is known that a plate piece having a tunnel-like cavity passing through the heating element is attached to the heat generating element as in Japanese Patent Application Laid-Open No. 55-12798, and is immersed in a medium liquid, and the plate piece is immersed in the medium liquid. The liquid is sucked in from below by the pumping action accompanying the bubble separation, so even if the amount of heat generated is considerably large, the entire heat transfer surface is not covered with a vapor film, thus improving the burnout heat load. However, this method has the disadvantage of poor performance at low heat loads because there is almost no place to hold steam within the cavity. Furthermore, the difference in thermal expansion between the element and the plate piece may cause stress to be applied to the element, reducing the reliability of the element. Furthermore, silicon, molybdenum, or the like can be used as the material of the plate piece in order to relieve stress, but there is a drawback that processing is not easy.

[Purpose of the invention]

The object of the present invention is to provide a heat transfer device that keeps the temperature difference required to transfer generated heat to a boiling medium small, regardless of the amount of heat generated, in cooling integrated circuit chips and other heat generating elements with high heat generation density. It is about providing.

[Summary of the invention]

The present invention provides heat transfer to a heat conductive member having a structure in which a large number of cavities and openings 1-1 are provided for absorbing liquid and escaping steam generated inside the tank, and cavities for stably holding a steam generation core. It is characterized by the provision of a liquid introduction part to improve performance.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1A and 1B, a heat transfer body] is attached to the back surface of the integrated circuit chip 5. As shown in FIGS. The heat transfer body 1 is composed of a microstructure member 2 in which a group of tunnels are formed, and a heat conduction member 3 that transmits heat generated from the integrated circuit to the microstructure, and between the integrated circuit 4 chip 5 and the microstructure member 2. The heat conductive member 3 is sandwiched between the two. The area for attaching the heat conductive member 3 to the microstructure is smaller than the bottom projected area of the microstructure member 2, and therefore the heat transfer member 1 is attached to the integrated circuit chip 5 after the heat transfer body bottom surface liquid introduction section 4. A gap is formed. A cooling system for an integrated circuit chip with a heat transfer body attached in this manner is shown in FIG. A wiring board 6 on which a large number of integrated circuit chips 5 to which a heat transfer body 1 is attached is mounted.
is vertically attached to the backboard 7, and the airtight container 8
incorporated within. The wiring board 6 is immersed in a non-conductive liquid 9, and the non-conductive liquid 9 boils and foams due to the heat generated by the integrated circuit chip 5. The vapor of the boiled non-conductive liquid 9 is condensed and liquefied in a condenser 11 provided at the top of the container 8, and then returned to the liquid section at the bottom of the container.

The fine structure of the heat transfer body 1 is made by laminating a plurality of fine fin perforated plates 31 shown in FIG.

The fine fins 32 and 33 of the perforated plate with fine fins form grooves 34- in the direction crossing each other from both the front and back sides of the thermally conductive thin plate.
, 35. The sum of the depths of the grooves 34, 35 is greater than the wall thickness of the sheet, so that at the intersection of each groove there is an opening 3 that communicates the respective grooves.
G is formed.

Although the shape of the thin plate is circular in FIG. 1, it may be rectangular. Also, the groove shape is square.

It may be of any shape such as circular or triangular.

Further, the material is preferably a highly thermally conductive material such as copper aluminum. FIG. 4 shows a structure in which a plurality of perforated plates 31 with fine fins are stacked one on top of the other and a heat conductive member 3 is bonded to each other. Grooves 34 and 35 shown in FIG. 3 form tunnel-like cavities 41 and 42, each of which is communicated by an aperture 36. As shown in FIG. The thermally conductive member 3 is not provided with any particular fine structure.

The material of the thermally conductive member 3 has excellent thermal conductivity and has a coefficient of thermal expansion comparable to that of silicon, which is the material of the integrated circuit chip.

Molybdenum is suitable. Note that the fine structure may be made of different materials. In addition, the number of layers and the size of the grooves of the perforated plate with fine fins in the microstructure, the size and thickness of the mounting area of the heat conductive member, the amount of heat generated by the integrated circuit chip, the material of the nonconductive liquid, etc. It is desirable that an optimum value exists depending on the value, and that processing is performed to that value.

The function of the heat transfer body in this example will be explained using FIG. 5. Fig. 5(a) shows the case where the heat transfer body 1 is attached to the integrated circuit chip 5 mounted vertically, and Fig. 5(b) shows the case where the heat transfer body 1 is attached to the integrated circuit chip 5 mounted horizontally. The figures show the respective cases in which they are installed. Figure 5(a), (
In b), solid arrows indicate the movement of liquid, and dashed arrows indicate the direction in which vapor escapes. In FIG. 5(,), steam evaporated on the tunnel wall escapes to the outside through vertically oriented tunnels 1 to 41. And the liquid is
A tunnel 42 and a tunnel 4J that are introduced into the heat transfer body from the bottom surface of the heat transfer body through the tunnel entrance connected to the outer surface of the heat transfer body and through the liquid introduction part 4 provided at the joint with the integrated circuit chip, and are oriented in the horizontal direction. It is supplied to the entire interior area of the heat transfer body through the opening 36 that connects the tunnel 42 with the heat exchanger. Additionally, the horizontal channels 42 can retain some of the steam generated at the walls, which acts as a nucleus for subsequent foaming, causing foaming to occur continuously. In FIG. 5(b), the openings 36 that connect the tunnels are continuous in the vertical direction, and play the role of the vertical tunnel described in (a) above. What previously functioned as a vertical tunnel now functions as a horizontal tunnel, and functions as a heat transfer body in exactly the same way.

By providing the liquid introduction part 4 at the joint between the integrated circuit chip and the heat transfer body, firstly, regardless of the orientation of the heat transfer body, liquid can be supplied to the center of the root, where liquid has not been sufficiently supplied in the past. It is possible to supply a sufficient amount of liquid, making it possible to smoothly supply the liquid over the entire area of the heat transfer body, and the openings that connect each tunnel in the vertical and horizontal directions to work efficiently. Second, it is possible to suppress the deterioration of heat transfer performance due to dryness of the center near the base of the heat transfer body, which is a problem during high heat generation. In other words, during high heat generation, the temperature of the heat transfer body is highest at the center near the base of the heat transfer body;
If the amount of liquid supplied does not match the amount of evaporation, and the heat transfer body is covered with steam, bar-out is likely to occur.

However, by providing the liquid introduction part in the part that dries most easily, the liquid is supplied sufficiently, and furthermore, the liquid flow in this area is directed from the introduction part, around the base of the heat transfer body, to the center. This occurs due to the inertial force, which makes it difficult for the vicinity of the base of the heat transfer body to be covered with steam. Due to the above effects, boiling of the liquid occurs extremely stably, a high heat transfer coefficient is obtained due to the intense movement and evaporation of the liquid within one hemnel, and burnout is difficult to occur.

FIG. 6 shows another embodiment of the invention. A heat conductive member 3 for forming a liquid introduction part 4 at the bottom of the heat transfer body 1 reaches inside the heat transfer body microstructure member 2. Although the structure of the tunnel group forming the microstructure has high cooling performance, since there are few solid parts, heat conduction is not sufficient from the surface of the heating element to the tip of the heat transfer element. In addition, liquid is not actively supplied to the periphery of the microstructured core. Therefore, the above drawbacks can be solved by extending the heat conducting member 3 so as to reach the central portion of this fine structure.

Furthermore, if a material with a coefficient of thermal expansion similar to that of silicon, which is the material of the integrated circuit chip 5, is selected as the material of the heat conduction member 3, it is possible to prevent the temperature of the integrated circuit chip 5 and the heat conduction member 3 from increasing as the temperature of the integrated circuit chip increases. No stress is generated between them due to the difference in thermal expansion. On the other hand, even if a material with a thermal expansion coefficient different from that of the thermally conductive member 3 is selected as the material for the microstructure member 2, stress due to the difference in thermal expansion will be absorbed by the portion of the thermally conductive member that reaches into the microstructure. Therefore, the reliability of the joint between the heat conductive member and the microstructure member can be improved. Therefore, the material of the microstructured member that is complicated to process can be arbitrarily selected from any material that is easy to process as long as it has high thermal conductivity. In addition, even if the number of solid parts is increased by using a heat conduction member, the heat conduction member is light because it is a material with a coefficient of thermal expansion similar to that of silicon, so the overall weight of the heat transfer body is reduced, and the integrated circuit chip and wiring board This reduces the load on the solder joints. The ratio of the heat conduction member to the microstructure, the iron base to the heat conduction member's microstructure, and the shape of the heat conduction member can be selected depending on the amount of heat generated and the physical properties of the liquid. .

FIG. 7 shows another embodiment of the present invention. In the embodiment shown in FIG. 6, a liquid introduction part 4-b is provided in the center of the microstructure as well as in the base of the heat transfer body. In this case, the liquid is supplied to the region 2-b of the fine structure part away from the heating element surface, and the vapor is smoothly deviated from the fine structure part. moreover,
Region 2a near the heating element surface of the fine structure where the temperature increases
The liquid is supplied to the two liquid introduction parts 4-a and 4. - A sufficient amount is made from both sides of b. Therefore, a high heat transfer coefficient can be obtained, and the burnout heat flux can be increased.

Note that the liquid introduction part provided in the microstructure may be provided in any part. Also, a plurality of them may be provided.

FIG. 8 shows another embodiment of the present invention. In this embodiment, the heat transfer body microstructure is formed by stacking and joining a thermally conductive thin plate 8 having grooves 82 on only one side so that the grooves of each thin plate are alternately orthogonal to each other. The grooves have a structure in which they communicate with each other through holes 83 formed at the bottom of the grooves.

〔Effect of the invention〕

According to the present invention, in the heat transfer body that removes heat generation by boiling the liquid and maintains the temperature Jα of the heating element below a limit value, the liquid is smoothly supplied into the heat transfer body, The temperature at the base of the heating element can be kept low by lowering the operating efficiency of the heat transfer element and by making it difficult to burn out.

[Brief explanation of drawings]

Figure 1A is a longitudinal cross-sectional view of the heat transfer body, and Figure 18 is A of Figure 1A.
-A-line cross-sectional view, Figure 2 is a perspective sectional view of an integrated circuit cooling system to which the present invention is applied, Figure 3 is a perspective sectional view of elements constituting the heat transfer body, and Figure 4 is a detail of the heat transfer body. A perspective sectional view showing the structure; FIGS. 5(a) and 5(b) are views for explaining the function of the heat transfer body; FIG. 6 is a sectional view of another embodiment of the present invention
FIG. 7 is a sectional view of another embodiment of the present invention, and FIG. 8 is a sectional view of another embodiment constituting a fine structure section. DESCRIPTION OF SYMBOLS 1... Heat transfer body, 2... Heat transfer body fine structure part, 3...
Heat conductive member, 4...Liquid introduction part, 5...Integrated circuit chip, 10...Boiling bubble, 31...Perforated plate with fine fins, 36...Opening hole, 41.42... ·tunnel. Y I Figure A Figure IF3 Figure A-A Axis ○ Not shown Z Figure 3 Figure 4 Figure - (7- Figure 5 Cb) Figure B Figure 7 Figure 4-H d-b

Claims (1)

[Claims] 1. A heat transfer body having a structure in which a plurality of elongated, parallel-extending cavities communicating with the outside are formed in a three-dimensional shape within the heat transfer body, and the first cavity groups communicate with each other is attached to a heat generating body. In the apparatus for cooling a heating element, the heating element and the first heat transfer element are connected by a heat conductive member having a cross-sectional area smaller than the heat transfer element, and a space is formed between the heating element and the heat transfer element, A heat transfer device characterized in that a group of cavities formed within the heat transfer body communicate with the space. 2. A heat transfer device according to claim 1, characterized in that a heat conductive member is embedded inside the heat transfer body. 3. The heat transfer device according to claim 1 or 2, characterized in that the heat transfer body is divided into a plurality of parts to form a space, and the cavity group and the divided space are communicated with each other. Device.