JP2008108781A - Cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system capable of cooling a local heat-generating section in a semiconductor chip. <P>SOLUTION: The cooling system has a heat treatment section 1 and a thermoelectric cooling element 20. The heat treatment section 1 has a heat-conducting plate 10, arranged on a conductor chip 40 and absorbs heat generated in the semiconductor chip 40; a heat radiation means 12 for radiating the heat absorbed by the heat-conducting plate 10; and a heat transfer device 14 for connecting the heat-conducting plate 10 to the heat radiation means 12 and transfers the heat. The thermoelectric cooling element 20 is embedded in a place that is a surface side in contact with the semiconductor chip 40 of the heat-conducting plate 10 and corresponds to the local heat generation section of the semiconductor chip 40 for installation, and is formed by a Peltier junction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cooling system, and more particularly to a cooling system for cooling a semiconductor chip.

  In recent years, electronic devices have built-in high-output, highly-integrated semiconductor chips such as a central processing unit (CPU) and a microprocessor (MPU). Semiconductor chips such as CPUs and MPUs have a very high degree of integration and perform processing such as calculation and control at high speed, so that a large amount of heat is released. A semiconductor chip that generates heat due to a large amount of heat is cooled by a cooling system using a thermoelectric cooling element (TEC), a heat pipe (HP), a vapor chamber (VC), a loop heat pipe (LHP), etc. Reference 1).

However, it is common for semiconductor chips to generate heat locally, and even if the entire surface of the semiconductor chip is cooled as in a conventional cooling system, sufficient heat removal is performed from local heat generation. I can't. For this reason, the temperature of the semiconductor chip may rise despite the low amount of input heat.
JP-A-8-70068

  An object of this invention is to provide the cooling system which can cool the local heat-emitting part of a semiconductor chip.

  According to one aspect of the present invention, a heat conduction plate that is disposed on a semiconductor chip and absorbs heat generated by the semiconductor chip, a heat release unit that dissipates heat absorbed by the heat conduction plate, and a heat conduction plate and heat release A heat treatment part having a heat transport device that connects means and transports heat, and a Peltier effect that is embedded in a portion corresponding to the local heating part of the semiconductor chip on the surface side of the heat conducting plate that contacts the semiconductor chip. The gist of the present invention is a cooling system including a thermoelectric cooling element.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling system which can cool the local heat generating part of a semiconductor chip can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  As shown in FIGS. 1A and 1B, the cooling system according to the embodiment of the present invention includes a heat conductive plate 10 that is disposed on a semiconductor chip 40 and absorbs heat generated by the semiconductor chip 40. A heat-dissipating means 12 for dissipating heat absorbed by the conductive plate 10; a heat treatment unit 1 having a heat-transporting device 14 for connecting the heat-conducting plate 10 and the heat-dissipating means 12 and transporting the heat; A thermoelectric cooling element 20 having a Peltier effect is provided on the surface side in contact with the chip 40 so as to be embedded in a portion corresponding to the local heating portion of the semiconductor chip 40.

  A recess for embedding and arranging the thermoelectric cooling element 20 is formed in the heat conductive plate 10 by an etching technique, a drill, or the like. The concave portion of the heat conducting plate 10 is formed at a location directly above the local heat generating portion of the semiconductor chip 40 when arranged on the semiconductor chip 40 such as a CPU and MPU. The heat conductive plate 10 can be made of a metal material having a high thermal conductivity such as copper (Cu) or aluminum (Al). The thickness of the heat conductive plate 10 is preferably 3 to 5 mm.

  The heat release means 12 is a fin or the like shaped so as to have a large surface area so that heat can be easily diffused. If the cooling capacity (heat diffusing capacity) is insufficient by natural cooling alone, the heat releasing means 12 can expand the cooling capacity even if it is the same size by installing a fan and forcibly increasing the amount of air movement. .

  The heat transport device 14 is a device that transports the heat absorbed by the heat conducting plate 10 to the heat release means 12. The heat transport device 14 is, for example, a heat pipe, a vapor chamber, a loop heat pipe, or the like that puts a refrigerant therein and exhausts heat by using latent heat of liquid evaporation and condensation.

  As shown in FIGS. 1 (a) and 1 (b), a "heat pipe" is a closed-loop electrothermal element that uses the latent heat of evaporation and condensation of a working fluid, which is a liquid. Make it possible. The heat pipe is made of a circular pipe and can be bent or flattened into a required shape when it is attached.

  The “vapor chamber” is a planar heat pipe as shown in FIG. The inside of the vapor chamber basically has a wick structure that promotes the circulation of the steam flow path and the working fluid, like the heat pipe. The vapor chamber, which is the heat transport device 14 vapor chamber, generates heat from the semiconductor chip 40 and receives heat absorbed by the heat conducting plate 10, whereby the working fluid takes away latent heat and evaporates. And since the vapor | steam of the working fluid flows toward the heat | fever discharge | release means 12 with low temperature, the heat | fever which generate | occur | produced with the semiconductor chip 40 spread | diffused, As a result, the semiconductor chip 40 is cooled.

  As shown in FIG. 4, the “loop heat pipe” is a heat release means 12 that radiates and condenses the working fluid from the evaporation portion 14 a disposed on the heat conduction plate 10 that receives heat from the semiconductor chip 40 and condenses. The heat transfer device (liquid flow tube) 14b in which the working fluid in the liquid phase circulates toward the evaporation portion 14a and the heat transport device (vapor flow tube in which the working fluid vapor flows) ) 14c and connected in a circular shape (loop shape). In the loop heat pipe, the working fluid is heated and evaporated by the heat generated by the semiconductor chip 40 transmitted to the evaporation unit 14a, and the vapor is sent out from the evaporation unit 14a via the heat transport device (vapor flow tube) 14c. It is. On the other hand, the liquid-phase working fluid is supplied from the heat transport device (liquid flow tube) 14b to the porous ceramic, that is, the wick, and the wick is in contact with the inner circumferential surface of the evaporation section 14a. Capillary pressure is generated, and as a result, the liquid-phase working fluid is supplied to the outer peripheral surface of the wick, that is, the inner peripheral surface of the evaporation section 14a. Since the liquid-phase working fluid is heated and evaporated and flows to the condensing unit 12a through the heat transport device (steam flow tube) 14c, heat can be transported as latent heat of the working fluid. Therefore, the heat generated by the semiconductor chip 40 is transported, and as a result, the semiconductor chip 40 is cooled. With the structure of the loop heat pipe as shown in FIG. 4, since the liquid phase working fluid and the working fluid vapor do not flow through the same location, there is no restriction on the heat transport capability due to the scattering limit.

  The thermoelectric cooling element 20 is a Vertier element that consists of two conductors made of different materials and operates as a heat pump that cools or heats both surfaces of the element when a direct current (DC) is passed through the two conductors. As shown in FIG. 5, the basic configuration of the thermoelectric cooling element 20 is such that P-type and N-type semiconductor elements are alternately arranged between two insulating heat transfer plates such as ceramics, and are electrically connected in series. In addition, they are thermally connected in parallel. As shown in FIG. 5, when a direct current is passed from the lead wire 22, the current flows in the direction of the arrow, and the upper surface becomes a heat absorption (cooling) surface and the lower surface becomes a heat generation (heating) surface.

  The operation of the thermoelectric cooling element 20 will be described in detail. As shown in FIG. 6, when the thermoelectric cooling element 20 is connected to a direct current power source, current flows from the lower side of the N-type semiconductor to the lower side of the P-type semiconductor through the upper electrode. At that time, the energy moves in the direction opposite to the current along with the electrons. In the N-type semiconductor, energy for electrons to move from the upper electrode to the N-type semiconductor and energy for moving the inside of the N-type semiconductor to the lower electrode are obtained from the upper electrode side. Energy is insufficient on the electrode side and the temperature is lowered. On the other hand, on the lower electrode side, the energy taken by the electrons is released and the temperature rises. On the other hand, in a P-type semiconductor, holes function similarly. As a result, the total amount of heat absorbed by the cooling surface is added to the amount of heat corresponding to the total supply power and released to the heat dissipation side. Heat absorption (cooling effect) is proportional to the current and the number of semiconductor elements to be installed.

  The thermoelectric cooling element 20 is installed so as to be embedded in a recess formed in the heat conducting plate 10. The thermoelectric cooling element 20 is installed through an insulating layer made of ceramic or the like so as not to be electrically connected to the heat conducting plate 10. As shown in FIG. 2, the lead wire 22 that supplies electric power to the thermoelectric cooling element 20 forms a hole in the heat conductive plate 10 and is wired through the heat conductive plate 10. The lead wire 22 is connected to a voltage control circuit (not shown) that controls the voltage supplied to the thermoelectric cooling element 20.

  The thermoelectric cooling element 20 is preferably embedded and installed so as to be substantially flush with the surface of the heat conducting plate 10. “Same surface” as used herein means that the surface of the heat conducting plate 10 and the surface of the thermoelectric cooling element 20 are in the same plane with no step. When the thermoelectric cooling element 20 is embedded and installed in the heat conductive plate 10, it is fixed with a heat conductive adhesive. In addition, since heat conduction deteriorates at the interface between the thermoelectric cooling element 20 and the semiconductor chip 40 to be cooled, thermal grease or the like having good thermal conductivity is used so that air does not enter. It is preferable.

  The installation position of the thermoelectric cooling element 20 is a location corresponding to the local heating part of the semiconductor chip 40. The local heat generating part of the semiconductor chip 40 can be specified by creating and analyzing a surface temperature distribution diagram with a thermograph. When there are a plurality of local heating portions of the semiconductor chip 40 based on the analysis result of the thermograph, it is possible to arrange a plurality of thermoelectric cooling elements 20.

  According to the cooling system according to the embodiment of the present invention, it is possible to cool the local heat generating portion of the semiconductor chip 40 by arranging the thermoelectric cooling element 20 at a location corresponding to the local heat generating portion of the semiconductor chip 40. The cooling performance can be improved. In other words, the temperature gradient on the surface of the semiconductor chip 40 can be made gentle by diffusing the heat generated in the local area of the semiconductor chip 40 to the heat conducting plate 10 using the thermoelectric cooling element 20. Cooling performance is improved.

  Further, according to the cooling system according to the embodiment, the heat absorbed by the heat conduction plate 10 is transported by the heat transport device 14 and the heat is released by the heat release means 12, so that the heat generated by the semiconductor chip 40 is heat. As a result, the semiconductor chip 40 is cooled as a result.

  Furthermore, according to the cooling system according to the embodiment, when the thermoelectric cooling element 20 is embedded and installed so as to be substantially flush with the surface of the heat conducting plate 10, there is no step, and the thermoelectric cooling element 20 and Since the area where the heat conductive plate 10 contacts the semiconductor chip 40 is increased, cooling can be efficiently performed.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques should be apparent to those skilled in the art.

  For example, in the embodiment, it has been described that a heat conductive adhesive is used as a method of bonding the thermoelectric cooling element 20 to the heat conductive plate 10, but it is also possible to bond with a solder. By joining the thermoelectric cooling element 20 and the heat conducting plate 10 with solder, it becomes possible to join with high thermal conductivity.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

FIG. 1A is a schematic plan view of a cooling system according to the embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of the cooling system according to the embodiment of the present invention. It is a typical perspective view of the cooling system which concerns on embodiment of this invention. It is FIG. (1) for demonstrating the heat transport device of the cooling system which concerns on embodiment of this invention. It is FIG. (2) for demonstrating the heat transport device of the cooling system which concerns on embodiment of this invention. It is FIG. (1) for demonstrating the thermoelectric cooling element of the cooling system which concerns on embodiment of this invention. It is FIG. (2) for demonstrating the thermoelectric cooling element of the cooling system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat processing part 10 ... Heat conduction board 12 ... Heat release means 12a ... Condensing part 14 ... Heat transport device 14a ... Evaporating part 20 ... Thermoelectric cooling element 22 ... Lead wire 40 ... Semiconductor chip

Claims (8)

A heat conductive plate disposed on the semiconductor chip for absorbing heat generated by the semiconductor chip; heat release means for radiating heat absorbed by the heat conductive plate; and connecting the heat conductive plate and the heat release means. A heat treatment section having a heat transport device for transporting heat;
A cooling system comprising: a thermoelectric cooling element having a Peltier effect, embedded in a portion corresponding to a local heat generating portion of the semiconductor chip, on a surface side of the heat conducting plate in contact with the semiconductor chip.   The cooling system according to claim 1, wherein the thermoelectric cooling element is installed so as to be substantially flush with a surface of the heat conducting plate.   The cooling system according to claim 1, wherein the thermoelectric cooling element is plural.   The cooling system according to claim 1, wherein the heat transport device is a heat pipe.   The cooling system according to claim 1, wherein the heat transport device is a vapor chamber.   The cooling system according to claim 1, wherein the heat transport device is a loop heat pipe.   The cooling system according to claim 1, wherein the heat release means is a fin.   The cooling system according to claim 7, wherein the heat release unit further includes a fan.

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