JP2014013849A - Heat dissipation structure for electronic apparatus - Google Patents

Abstract

Disclosed is a heat dissipation structure for an electronic device that can easily cool a plurality of electronic components having different heights.
An electronic component that generates heat when energized is mounted on a substrate, and the plurality of electrons are mounted on a heat diffusion plate disposed so as to cover the upper surface side of the plurality of electronic components. A heat dissipation structure for an electronic device configured to transfer heat from the components 1 and 3, wherein the electronic components 1 and 3 include an electronic component 1 having a high height and a low electronic component 3 measured from the substrate 2. The heat transfer member 7 in which the working fluid 8 that is heated to evaporate and radiates and condenses is enclosed in the sealed container 7a, and the container 7a expands when the working fluid evaporates. However, it is interposed at least between the upper surface of the electronic component 3 having a low height and the lower surface of the heat diffusion plate 6.
[Selection] Figure 1

Description

  The present invention relates to a heat dissipation structure for cooling an electronic device by dissipating heat from an electronic component such as a central processing unit (CPU).

  Electronic parts such as CPUs of personal computers tend to increase in heat dissipation year by year as their speed and performance increase. However, on the contrary, the semiconductor chip size has become the same size or smaller than the conventional size due to the advancement of fine silicon circuit technology, and the heat flux per unit area is high. Therefore, in order to avoid problems caused by the temperature rise, it is required to effectively dissipate and cool electronic components. Therefore, the electronic component is provided with a heat dissipation structure including a heat pipe, a heat spreader (IHS), and the like. An apparatus having such a heat dissipation structure is described in Patent Document 1.

  The apparatus described in Patent Document 1 includes a printed circuit board having an aperture, a heating element mounted on the aperture on one side of the printed circuit board, and a plane mounted on the other side of the printed circuit board. The flat heat pipe has a convex part in the heat absorption part, and the convex part is inserted into the opening part and is mounted so as to be in thermal contact with the heating element. It has a heat dissipation structure.

JP 2000-156484 A

  By the way, when a heat spreader is attached to an electronic component to be cooled, heat is diffused to a heat spreader having a large heat radiation area, and then is radiated from a heat pipe or a heat sink attached to the heat spreader. The heat spreader is formed in a flat shape in order to maintain good thermal contact with the electronic component. However, the plurality of electronic components arranged on the substrate have different heights and arrangement locations. Therefore, when cooling a plurality of electronic components, it is necessary to attach a heat spreader to each electronic component, which causes a problem in terms of cost. In addition, when cooling a plurality of electronic components with a single heat spreader, it is necessary to form the heat spreader in consideration of the height and location of each electronic component. In such a structure, the structure of the heat spreader is complicated. At the same time, the state in which the plurality of electronic components are appropriately brought into contact with each other at the same time cannot be continued, and the heat of the electronic components may not be radiated well.

  The present invention has been made paying attention to the above technical problem, and an object thereof is to provide a heat dissipation structure for an electronic device that easily cools a plurality of electronic components having different heights.

  In order to achieve the above object, an invention according to claim 1 is directed to a heat diffusion plate in which an electronic component that generates heat when energized is mounted on a substrate and arranged to cover the upper surface side of the plurality of electronic components. In the heat dissipation structure for an electronic device configured to transmit heat from the plurality of electronic components, the electronic component includes an electronic component having a high height and a low electronic component measured from the substrate, and is sealed. A heat transfer member that heats and evaporates and heats to dissipate and condenses inside the container is enclosed, and the heat transfer member that expands the container by evaporating the working fluid is at least a low height of the electronic component Is interposed between the upper surface of the heat diffusion plate and the lower surface of the heat diffusion plate.

  According to a second aspect of the present invention, in the first aspect of the present invention, the first heat transfer surface that contacts the upper surface of the electronic component of the container and the second heat transfer surface that faces the lower surface of the heat diffusion plate are provided. A side wall portion formed on a flat surface and connecting the first heat transfer surface and the second heat transfer surface is configured to expand and contract in the vertical direction according to the pressure inside the container. This is a heat dissipation structure for an electronic device.

  The invention according to claim 3 is the heat dissipation structure for an electronic device according to claim 2, wherein the side wall portion is formed in a bellows shape.

  According to the present invention, the heat diffusion plate is disposed so as to cover the upper surface side of a plurality of electronic components having different heights from the substrate, and between the upper surface of the electronic component having a low height and the lower surface of the heat diffusion plate. A heat transfer member is interposed between the two. Therefore, when the heat diffusion plate is configured on a simple flat plate, the electronic component having a high height is in direct contact with the heat diffusion plate so that heat can be transferred, and the electronic component having a low height is diffused through the heat transfer member. It contacts the board so that heat can be transferred. In other words, even if the heights of the plurality of electronic components that transmit heat to the heat diffusion plate are different, the heat diffusion plate does not need to be bent according to the height difference, and is a simple flat plate. Can be configured in shape.

  Further, in the present invention, the heat transfer member encloses a working fluid that is heated and evaporated and radiates and condenses in the container, and the container expands when the working fluid is heated and evaporated. It is configured. Therefore, when the electronic component generates heat and the electronic component is to be cooled, the container of the heat transfer member expands to fill the gap between the upper surface of the electronic component and the lower surface of the heat diffusion plate. The heat resistance between the electronic component and the heat transfer material and between the heat transfer member and the heat diffusion plate can be automatically reduced. Furthermore, since the heat transfer member transfers heat from the lower surface side to the upper surface side as latent heat of the working fluid enclosed in the container, the heat transfer from the electronic component side to the heat diffusion plate side can be promoted, and as a result Thus, a heat dissipation structure with good heat dissipation characteristics or cooling efficiency of electronic components can be obtained.

It is sectional drawing which shows an example of the thermal radiation structure for electronic devices which concerns on this invention. It is sectional drawing for demonstrating the process in which the vapor chamber shrink | contracts. It is sectional drawing for demonstrating the process in which the vapor chamber expand | swells. It is sectional drawing which shows the other example of the thermal radiation structure for electronic devices which concerns on this invention.

  Next, the present invention will be described based on specific examples. The electronic component targeted by the present invention is an electronic component that generates heat during operation of an integrated circuit, a memory, or a CPU. The heat diffusion plate (also referred to as heat spreader or heat conduction plate) in the present invention is arranged so as to cover the upper surface side of a plurality of electronic components having different heights, and there is a gap between at least one electronic component. Existing. The heat transfer member according to the present invention is configured such that a condensable fluid is sealed as a working fluid in a sealed container, and heat is transferred in the form of latent heat of vaporization of the working fluid. The evaporation part that takes heat away from the heat and the condensation part that transmits the heat to the heat spreader are formed as a part of the container, and the part between the evaporation part and the condensation part or the evaporation part and the condensation part are connected. A side wall part is comprised so that it may expand-contract according to the pressure inside a container. That is, the heat transfer member employed in the present invention is constituted by a heat pipe or a vapor chamber. In a specific example described below, a thermosiphon vapor chamber configured to recirculate the working fluid by gravity is used. Further, the vapor chamber is interposed between the heat spreader and the electronic component, expands in accordance with the heat of the electronic component, fills the gap, and heat transports in the form of latent heat to transfer the heat of the electronic component to the heat spreader. Is configured to communicate.

  FIG. 1 shows an example of a heat dissipation structure for an electronic device according to the present invention. The CPU 1 as an example of an electronic component has a structure similar to that conventionally known, and is a member in which a circuit is formed on a silicon chip and a section having a thickness of about several millimeters has a rectangular shape. The CPU 1 is mounted on a substrate 2, and a memory 3 is mounted on the substrate 2 as another electronic component. The memory 3 has the same structure as that conventionally known, and is a member having a thickness of about several millimeters. The height from the substrate 2 is lower than that of the CPU 1. The substrate 2 is attached to the mother board 4 by a solder dump 5.

  A heat spreader 6 is disposed so as to cover the upper surfaces of the CPU 1 and the memory 3. The heat spreader 6 is for dissipating heat generated from the electronic component, and is formed of a material having high thermal conductivity such as copper or aluminum. As shown in FIG. 1, the heat spreader 6 includes a flat plate portion 6a covering the upper surface side of the CPU 1 and the memory 3, a leg portion 6b extending from the side edge portion of the flat plate portion 6a toward the substrate 2, and a lower end of the leg portion 6b. And a flange portion 6c formed on the portion, and is fixed to the substrate 2 by the flange portion 6c.

  The height of the flat plate portion 6a supported by the leg portion 6b is substantially equal to the CPU 1 having a high height from the substrate 2 of the CPU 1 and the memory 3, and therefore the upper surface of the CPU 1 and the lower surface of the heat spreader 6 are the same. (The lower surface of the flat plate portion 6a) are close to each other and face each other or are in close contact with each other. On the other hand, since the height of the memory 3 from the substrate 2 is lower than the height of the flat plate portion 6a, the upper surface of the memory 3 and the lower surface of the heat spreader 6 (the lower surface of the flat plate portion 6a) are greatly separated and a gap is left. Yes.

  In order to reduce the thermal resistance between the CPU 1 and the flat plate portion 6a, an organic or inorganic high thermal conductivity member (TIM: Thermal Interface Material) (not shown) is provided between the CPU 1 and the flat plate portion 6a. . The TIM transfers heat generated from the CPU 1 to the heat spreader 6 and is composed of thermal grease, a heat conductive sheet, or the like having high thermal conductivity. The CPU 1 and the heat spreader 6 can be joined to each other by soldering, brazing, or an adhesive.

  On the other hand, a heat transfer member is interposed in the gap between the upper surface of the memory 3 and the lower surface of the flat plate portion 6a so as to fill the gap. The heat transfer member is configured to transport heat in the form of latent heat of evaporation of the working fluid, such as a vapor chamber or a heat pipe. In the vapor chamber 7, as shown in FIG. 2, a condensable fluid is sealed as a working fluid 8 inside a sealed container 7 a, and the container 7 a is an evaporation that takes heat from the memory 3 that is an electronic component. Part 9, condensing part 10 that dissipates heat so as to transmit the heat to heat spreader 6, and side wall part 11 that connects evaporation part 9 and condensing part 10 and expands and contracts according to the internal pressure. .

  The working fluid 8 is a fluid that heats and evaporates, dissipates heat and condenses, thereby transporting heat in the form of latent heat, and is appropriately selected according to the temperature at which the vapor chamber 7 is used. The non-condensable gas is preferably a fluid that evaporates or boils at a low temperature of about 30 ° C. inside the container 7a from which the non-condensable gas is deaerated. For example, water, alcohol, or alternative chlorofluorocarbon is used as the working fluid 8. The working fluid 8 is sealed in the container 7a in a state where non-condensable gas such as air is degassed from the container 7a of the vapor chamber 7. The working fluid 8 is heated and evaporated to increase the internal pressure of the container 7a, and the vapor chamber 7 expands accordingly.

  The container 7a as a whole is formed of a metal material having high thermal conductivity such as copper and good wettability of the working fluid 8, and the evaporation portion 9 is a flat wall portion formed in a plate shape. The outer surface 9a is brought into close contact with and fixed to the memory 3 by a heat conductive epoxy resin or solder so as to absorb the heat generated in the memory 3. Then, due to the heat transferred to the evaporation unit 9, the liquid-phase working fluid 8 evaporates in the container 7 a in the evaporation unit 9. That is, heat is absorbed as latent heat.

  The condensing part 10 is another flat wall part formed in a plate shape and faces the evaporation part 9. Then, the working fluid 8 dissipates heat and condenses in the condensing unit 10. The circulating flow accompanied by the above-described evaporation and condensation of the working fluid 8 is generated, and heat is transferred (transported) from the memory 3 to the heat spreader 6. The liquid-phase working fluid 8 radiated and condensed by the condensing unit 10 is configured to drip from the condensing unit 10 or flow down through the side wall 11 and return to the evaporation unit 9.

  The side wall portion 11 is a portion that connects the end portions of the evaporation portion 9 and the condensation portion 10, and so that the interval between the evaporation portion 9 and the condensation portion 10 changes, that is, the condensation portion 10 moves up and down. Thus, it is formed in a curved shape. In addition, the side wall part 11 can be formed thinner than the thickness of the evaporation part 9 or the condensation part 10 so that it can expand and contract easily according to the change of the internal pressure of the container 7a. That is, when the internal pressure of the vapor chamber 7 rises due to the heating and evaporation of the liquid-phase working fluid 8, the side wall portion 11 extends in the axial direction as shown in FIG. 3 and the lower surface 6 d of the heat spreader 6. And the condensing unit 10 are in close contact with each other. Further, when the internal pressure of the vapor chamber 7 decreases, the side wall portion 11 is deformed so as to spread laterally as shown in FIG. 2, and the condensing unit 10 is separated from the lower surface 6 d of the heat spreader 6. . Note that the side wall portion 11 only needs to be configured to easily expand and contract in the axial direction, and may be formed of a plastic resin having elasticity.

  Therefore, in the heat dissipation structure for an electronic device according to the present invention, the heat generated by the CPU 1 is transmitted to the heat spreader 6 that is in contact therewith, and is further dissipated from the heat spreader 6 to the surrounding air. Alternatively, it is transmitted from the heat spreader 6 to a heat sink (not shown) to radiate heat to the outside air. Eventually, the heat of the CPU 1 is dissipated into the air and the CPU 1 is cooled.

  On the other hand, when the memory 3 is not operating and no heat is generated, the working fluid 8 does not evaporate, so that the vapor chamber 7 does not expand as shown in FIG. Further, when the memory 3 is operated and heat is generated, the heat is transmitted to the evaporation section 9 of the vapor chamber 7 that is in contact therewith. Since the working fluid 8 boils or evaporates at a low temperature, the working fluid 8 evaporates due to the heat, and the vapor flows to a portion where the temperature and pressure are low. That is, when the internal pressure of the container 7 a increases due to evaporation of the working fluid 8, the side wall 11 of the vapor chamber 7 extends and the condensing unit 10 contacts the lower surface 6 d of the heat spreader 6 as shown in FIG. 3. At this time, the condensing part 10 and the heat spreader 6 are in contact with each other because they are flat surfaces. That is, the vapor chamber 7 expands as the working fluid 8 evaporates due to the heat of the memory 3, and as a result, the vapor chamber 7 acts to fill the clearance between the heat spreader 6 and the memory 3.

  Thereafter, the vapor of the working fluid 8 dissipates heat and condenses, and the heat of the working fluid 8 is transmitted from the upper surface 10a side of the condensing unit 10 to the heat spreader 6 and further dissipated from the heat spreader 6 to the surrounding air. It is done. Alternatively, it is transmitted from the heat spreader 6 to a heat sink (not shown) to radiate heat to the outside air. When the vapor in the vapor chamber 7 is cooled by the condensing unit 10, the working liquid is refluxed to the evaporation unit 9 by gravity on the inner surface of the side wall 11. Eventually, the heat of the memory 3 is dissipated into the air, and the memory 3 can be cooled.

  Therefore, the heat generated in the CPU 1 is transmitted to the heat spreader 6 so that the CPU 1 can be cooled, and the vapor chamber 7 that expands as the working fluid 8 evaporates due to the heat of the memory 3 has the memory 3 and the heat spreader. 6, the heat of the memory 3 can be transmitted to the heat spreader 6 in the form of latent heat of the working fluid 8, and as a result, the heat spreader 6 having a simple shape in which the leg portion 6 b is provided on the flat plate portion 6 a. Even so, it is possible to easily dissipate heat from a plurality of electronic components having different heights to cool the electronic components.

  Note that the present invention is not limited to the specific example described above, and the vapor chamber has a condensable fluid sealed therein as a working fluid, an evaporation unit that takes heat away from the electronic component, and its heat As long as it is constituted by a condensing part that transmits the heat to the heat spreader, an evaporating part and the condensing part, and an expansion / contraction part that can contract and expand according to the heat of the electronic component, as shown in FIG. The side wall 13 of the vapor chamber 12 may be formed in a bellows shape that can be expanded and contracted. Further, in the present invention, it is only necessary that the above-described heat transfer member is interposed between the electronic component having a low height and the heat diffusing plate, and therefore, between all of the plurality of electronic components and the heat diffusing plate. A heat transfer member may be interposed. Furthermore, in the present invention, the TIM described above may be interposed between the heat transfer member and the heat diffusion plate.

  DESCRIPTION OF SYMBOLS 1 ... CPU (electronic component), 2 ... Board | substrate, 3 ... Memory (electronic component), 6 ... Heat spreader (thermal diffusion plate), 7 ... Vapor chamber (heat transfer member), 7a ... Container, 8 ... Working fluid, 9 ... Evaporating section, 10 ... condensing section, 11 ... side wall section.

Claims (3)

An electronic component that is mounted on a substrate to generate heat when energized and is configured to transfer heat from the plurality of electronic components to a heat diffusion plate disposed to cover the upper surface side of the plurality of electronic components. In the heat dissipation structure for equipment,
The electronic component includes an electronic component having a high height and a low electronic component measured from the substrate,
A working fluid that is heated to evaporate and radiates and condenses is enclosed inside the sealed container, and the heat transfer member that expands the container by evaporating the working fluid has at least a low height. A heat dissipation structure for an electronic device, which is interposed between an upper surface of an electronic component and a lower surface of the heat diffusion plate.   A first heat transfer surface contacting the upper surface of the electronic component of the container and a second heat transfer surface facing the lower surface of the heat diffusion plate are formed on a flat surface, and the first heat transfer surface and the second heat transfer surface are formed. 2. The heat dissipation structure for an electronic device according to claim 1, wherein a side wall portion connected to a hot surface is configured to expand and contract in a vertical direction according to a pressure inside the container.   The heat dissipation structure for an electronic device according to claim 2, wherein the side wall portion is formed in a bellows shape.

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