JP2007183021A - Sheet-shaped heat pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin and flexible sheet-shaped heat pipe having stable cooling performance. <P>SOLUTION: This sheet-shaped heat pipe comprises a sheet-shaped container constituted by sticking sheets 1, 4 opposite to each other by an adhesive film 2 at their peripheral portions and sealing them, metallic layers 7, 8 as wick layers formed on a container inner wall surface and provided with grooves 5 exerting capillary force, a plurality of spacers 3 fixedly arranged to prescribed positions of the metallic layer 8 of the sheet 4 so that cut faces of approximately-cylindrical small pieces obtained by cutting a metallic wire rod are placed vertically to the container inner wall face, and working fluid sealed inside of the sheet-shaped container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet-like heat pipe that cools an electronic component that generates a large amount of heat.

  Conventionally, notebook computers, PDAs, mobile phones, video cameras, and other electronic devices that have been noticeably smaller, thinner, lighter, and densely packed, have a large amount of heat generated from heat generation from electronic components and drive units. This is one of the causes of shortening the product life and requires cooling. However, there are many cases where it is not possible to secure a space for installing a heat sink or a heat fan in the heat generating part in a small and thin case. In such a case, the heat of the heat generating part is transferred to the case by a sheet heat pipe. Further, a method of dissipating heat by moving to a heat dissipating plate or a heat dissipating fan provided in a housing has been adopted.

  For example, in (Patent Document 1), a working liquid is sealed in a vacuum-sealed film-like container, and a steam channel and a wick for refluxing the working liquid are formed inside the container. Heat pipes have been proposed.

In addition, (Patent Document 2) proposes a sheet-like heat pipe that includes a working fluid and a spacer that exhibits capillary force in a foil-like container and is housed in a movable state with a flow path. Yes.
JP 2001-165854 A JP 2004-28557 A

  As described above, the sheet-shaped heat pipe of (Patent Document 1) has a structure in which a plurality of metal core wires serving as spacers are arranged at intervals, so that the distance between the spacers is made constant as the total product length increases. It was difficult to stick while maintaining, and the cooling performance of the heat pipe might become unstable.

  Moreover, in the sheet-like heat pipe of (Patent Document 2), the slit provided in the spacer serves as a flow path for the working fluid and the steam flow path, so that a part of the steam flow path is narrowed by the working fluid. It is easy to block, and the cooling performance of the heat pipe may be lowered. Moreover, since the spacer provided with the slit is in the form of a sheet, there is a problem that the spacer becomes thicker as the height of the steam flow path increases, and the flexibility decreases.

  In view of the above problems, an object of the present invention is to provide a sheet-like heat pipe that is thin, flexible, and has stable cooling performance.

  In order to solve the above problems, the present invention provides a container in which a plurality of metal wires are cut into a fixed position in a predetermined position in a container that is manufactured by sealing sheets with the sheets facing each other and sealing the periphery. The spacer layer, the working fluid, and the wick layer that exerts capillary force are provided.

  With this configuration, a constant steam flow path is stably secured around the spacer portion even if it is bent inside the container, and each spacer has a substantially cylindrical cut wire piece dispersedly arranged. Flexibility is maintained even when it grows larger. Also, by fixing the spacer to the inner wall surface of the container by soldering, there is no outgassing from the joint, and since the spacer is a substantially cylindrical small piece cut from a metal wire, the variation in wire diameter is small and the periphery of the spacer Thus, the height of the steam flow path can be kept uniform, and stable cooling performance can be obtained.

  The sheet-like heat pipe according to claim 1 of the present invention is a sheet-like container in which sheet-like members are opposed to each other and sealed by adhering the peripheral part, and a wick layer that exhibits a capillary force formed on the inner wall surface of the container. A plurality of spacers fixedly arranged at predetermined positions on the wick layer so that the cut surface of the substantially cylindrical small piece obtained by cutting the metal wire is perpendicular to the inner wall surface of the container, a working fluid sealed inside the container, It is equipped with. This configuration has a high flexibility, and has an effect that a steam flow path that can secure a stable heat transport amount can be formed.

  According to the sheet-shaped heat pipe of the first aspect of the present invention, the substantially cylindrical small pieces obtained by cutting the metal wire are used as spacers so that the cut surfaces are perpendicular to the inner wall surface of the container. In addition, it is possible to provide a sheet heat pipe having a large amount of heat transport and a high degree of freedom in designing the outer shape.

  The sheet-like heat pipe according to claim 2 of the present invention is a composite material in which the sheet member is a soft metal member or at least a metal layer. As a result, the inner wall surface of the container becomes a metal layer, so that a wick layer that easily exhibits capillary force can be formed.

  According to the sheet-like heat pipe of claim 2, the sheet-like member is a soft metal member or a composite material having at least a metal layer, so that the inner wall surface of the container becomes a metal layer, and the wick layer and the spacer Has an effect that can be firmly soldered.

  The sheet-like heat pipe according to claim 3 of the present invention is a stranded wire in which the metal wire is a thin metal wire. Thus, by using a spacer formed by twisting a plurality of fine metal wires, the spacer itself has an action of exerting a capillary force.

  According to the sheet-like heat pipe of the third aspect of the present invention, since the metal wire is a stranded wire made of a fine metal wire, the spacer itself has a capillary force, so that there is an effect that a high heat transport amount can be obtained.

  In the sheet-like heat pipe according to claim 4 of the present invention, the wire diameter of the spacer made of a substantially cylindrical piece obtained by cutting a metal wire is smaller than the spacer length. As a result, the arrangement in which the central axes of all the spacers are made parallel to the sheet is facilitated, and the gap amount in the container can be unified with the spacer wire diameter, so that the variation in performance is reduced.

  According to the sheet-shaped heat pipe of claim 4 of the present invention, the spacer wire diameter is smaller than the spacer length, so that a predetermined arrangement can be easily and stably performed using a template or the like, and stable cooling performance is obtained. There is an effect that it is.

  In the sheet-like heat pipe according to claim 5 of the present invention, the surface of the metal wire is covered with a solder alloy, and is fixed on the wick layer by solder bonding. As a result, in addition to high bonding strength, no outgas is generated from the bonded portion, so that the state in the container can be stably maintained for a long time.

  According to the sheet-like heat pipe of the fifth aspect of the present invention, since the spacer is fixed on the wick layer by solder bonding, there is an effect that stable cooling performance can be obtained.

  The sheet-like heat pipe according to claim 6 of the present invention has a groove shape in which the wick layer is formed on the inner wall surface. Thereby, the capillary force is exhibited along the groove, and the working fluid can be efficiently moved from the heat radiating portion to the heat receiving portion.

  According to the sheet-like heat pipe of claim 6 of the present invention, since the wick layer is a groove formed by pattern-etching the inner wall surface of the sheet, it is excellent in flexibility because a wick layer is unnecessary. effective.

  The sheet-like heat pipe according to claim 7 of the present invention is a roughened surface layer in which the wick layer is formed by roughening the inner wall surface. Thereby, a capillary force is exhibited along the roughened surface, and the working fluid can be efficiently moved from the heat radiating portion to the heat receiving portion.

  According to the sheet-like heat pipe of claim 7 of the present invention, since the wick layer is a roughened surface obtained by roughening the inner wall surface of the sheet, the effect that the wick layer is unnecessary and the flexibility is excellent. is there.

  The sheet-like heat pipe according to claim 8 of the present invention has a mesh shape in which a wick layer is formed on the inner wall surface. Thereby, the capillary force is exhibited along the mesh, and the working fluid can be efficiently moved from the heat radiating portion to the heat receiving portion.

  According to the sheet-like heat pipe of claim 8 of the present invention, since the wick layer is a mesh material formed on the inner wall surface of the sheet, there is an effect that stable cooling performance can be obtained.

  The sheet-like heat pipe according to claim 9 of the present invention is a metal mesh layer in which a wick layer is formed on the inner wall surface. Thereby, a capillary force is exhibited along the metal mesh layer, and the working fluid can be efficiently moved from the heat radiating portion to the heat receiving portion.

  According to the sheet-like heat pipe of claim 9 of the present invention, since the wick layer is a metal mesh layer formed on the inner wall surface of the sheet, there is an effect that stable cooling performance can be obtained.

(Embodiment 1)
First, in Embodiments 1 and 2, the sheet-like heat pipe structure will be described, and structural examples in the container of the sheet-like heat pipe will be described in Embodiments 3 to 6.

  FIG. 1 is a diagram showing a sheet-like heat pipe according to Embodiment 1 of the present invention. FIG. 1A and FIG. 1B are exploded perspective views, and are composed of a sheet 1, an adhesive film 2, a spacer 3, a sheet 4, and a groove 5. 1C is a cross-sectional view taken along the line AA ′ of FIG. 1A. The sheet 1 includes a resin layer 6 and a metal layer 7, and the sheet 4 includes a metal layer 8 and a resin layer 9. A steam channel 11 is formed by a gap between the metal layers 7 and 8 due to the above.

  As shown in FIG. 1A and FIG. 1B, a spacer 3 made of a substantially cylindrical piece obtained by cutting a metal wire is fixed to the groove 5 surface side of the sheet 4, and the groove 5 of the sheet 4 and the sheet 1 The groove | channel 5 is made to oppose and it bonds together with the adhesive film 2, and forms a sheet-like container. An appropriate amount of working fluid is sealed in the sheet container. The adhesive film 2 used for the bonding is preferably one that does not generate outgas. In addition to the adhesive film, the periphery of the sheet 1 and the sheet 4 such as solder bonding, silver solder bonding, and ultrasonic bonding can be bonded and sealed. Other methods may be used as long as they are methods.

  A plurality of grooves 5 through which the working fluid moves are arranged, and the pattern shape of the grooves 5 may be any pattern shape as long as the capillary force can be efficiently exhibited. Since the spacers 3 made of substantially cylindrical small pieces obtained by cutting the metal wire are distributed on the sheet 4 and a space is generated between the spacers 3, the reduction in flexibility of the sheet 1 and the sheet 4 is minimized. The steam channel 11 can be secured.

  As shown in FIG. 1C, a joint 10 is provided between the surface of the metal layer 8 and the spacer 3. The joining portion 10 is solder joining. As a joining method, the spacer 3 whose surface is coated with a solder alloy is disposed at a predetermined position on the metal layer 8, and the metal layer 8 and the spacer 3 are melted at the solder alloy melting temperature. The spacer 3 is soldered on the metal layer 8 by being heated and melted until it is cooled. Alternatively, the solder paste may be screen-printed at a predetermined position on the metal layer 8, the spacer 3 may be disposed on the solder paste, and the solder paste may be melted and cooled to be joined. As a method other than solder bonding, a low outgas adhesive, ultrasonic bonding, or the like may be used.

  A groove 5 is formed by a method such as pattern etching on the surface side of the metal layers 7 and 8 which is inside the sheet-like container, and has a function as a wick layer. Since the internal pressure of the container is set to be equal to or lower than the atmospheric pressure, if the metal layers 7 and 8 become too thin, the metal layers 7 and 8 are greatly deformed and the space for the vapor channel 11 cannot be secured. For this reason, the resin layers 6 and 9 are provided on the sheet 1 and the sheet 4, respectively, in order to increase the rigidity. However, if the space of the steam channel 11 can be sufficiently maintained by the rigidity of the metal layers 7 and 8, the sheet 1 And the resin layers 6 and 9 of the sheet 4 may be eliminated.

  The cross-sectional shape of the groove 5 is desirably 15 μm or more in depth and 100 μm or more in width. The spacer 3 preferably has a wire diameter of 0.4 mm or more and a length of 5 mm or less. Accordingly, the working fluid vaporized in the heat receiving part is moved to the heat radiating part (not shown) through the steam channel 11 without reducing the flexibility of the seat 1 and the sheet 4, and the working fluid liquefied in the heat radiating part is The movement to the heat receiving portion (not shown) by the groove 5 can be performed efficiently and stably.

  In the first embodiment, it is necessary to regularly arrange the spacers 3 at predetermined positions. However, by making the axial length of the spacers 3 larger than the wire diameter of the spacers 3, batch arrangement can be performed using a template or the like. Is possible. Further, the number of the spacers 3 is not limited depending on the size of the housing, but is about several tens to several hundreds if the spacers 3 are arranged at equal intervals. As a result, it is possible to provide a sheet-like heat pipe having a high heat transport capability and a stable cooling performance without impairing flexibility.

(Embodiment 2)
FIG. 2 is a diagram showing a sheet-like heat pipe according to Embodiment 2 of the present invention. FIG. 2A and FIG. 2B are exploded perspective views, which are composed of a sheet 1, an adhesive film 2, a spacer 3, a sheet 4, and a groove 5. 2C is a cross-sectional view taken along the line BB ′ of FIG. 2A. The sheet 1 includes a resin layer 6 and a metal layer 7, and the sheet 4 includes a metal layer 8 and a resin layer 9. The difference between the second embodiment and the first embodiment is the arrangement position and number of spacers 3, and the arrangement position and number of spacers 3 are free according to the outer shape, thickness and heat transport capacity of the sheet-like heat pipe. Can be set. However, if the number of the spacers 3 is too large or the arrangement positions are irregular, the flexibility of the sheets 1 and 4 may be reduced and the steam flow path 11 may be blocked. It is necessary to arrange according to the specifications.

(Embodiment 3)
FIG. 3 is a cross-sectional view of the sheet-like heat pipe according to the third embodiment of the present invention, in which the surfaces of the metal layers 7 and 8 are roughened instead of the grooves 5 of the first and second embodiments, It has become. By this roughening, a capillary force is exerted on the surfaces of the metal layers 7 and 8, and the working fluid can be moved from the heat radiating portion to the heat receiving portion. Surface roughening is performed by physical treatment such as sandblasting or chemical treatment such as chemical polishing, and the surface roughness Ra value is desirably Ra = 0.2 to 1 μm. Further, the resin layers 6 and 9 may be eliminated, and only the metal layers 7 and 8 may be used.

(Embodiment 4)
FIG. 4 is a cross-sectional view of the sheet-like heat pipe according to Embodiment 4 of the present invention. Instead of the groove 5 of Embodiments 1 and 2, the sheet-like metal mesh layer 14 as a wick layer exerts capillary force. It is provided for. The metal mesh layer 14 is provided between the metal layer 7 and the spacer 3 and is fixed to the metal layer 7 by soldering or the like. When the capillary force is exerted on the metal mesh layer 14, the working fluid can be moved from the heat radiating portion to the heat receiving portion. Further, the resin layers 6 and 9 may be eliminated, and only the metal layers 7 and 8 may be used. When this sheet-like heat pipe is attached, it is installed so that the resin layer 6 or the metal layer 7 is in contact with the heat receiving portion and the heat radiating portion.

(Embodiment 5)
FIG. 5 is a cross-sectional view of the sheet-like heat pipe according to the fifth embodiment of the present invention, and the sheet-like metal mesh layer 13 as a wick layer exerts a capillary force instead of the groove 5 of the first and second embodiments. It is provided for. The spacer 3 is arranged and fixed on one side of the metal mesh layer 13. When the capillary force is exerted on the metal mesh layer 13, the working fluid can be moved from the heat radiating portion to the heat receiving portion. Further, the resin layers 6 and 9 may be eliminated, and only the metal layers 7 and 8 may be used. When this sheet-like heat pipe is attached, it is installed so that the resin layer 9 or the metal layer 8 is in contact with the heat receiving portion and the heat radiating portion.

(Embodiment 6)
FIG. 6 is a cross-sectional view of the sheet-like heat pipe according to the sixth embodiment of the present invention. Instead of the grooves 5 of the first and second embodiments, the sheet-like metal mesh layers 13 and 14 as the wick layer have a capillary force. In order to exhibit it, it is provided on the surface of the metal layers 8 and 7, respectively. The spacer 3 is disposed and fixed on one side of the sheet-like metal mesh layer 13, and a sheet-like metal mesh layer 14 is provided with the spacer 3 interposed therebetween. When the capillary force is exerted on the metal mesh layers 13 and 14, the working fluid can be moved from the heat radiating portion to the heat receiving portion. Further, the resin layers 6 and 9 may be eliminated, and only the metal layers 7 and 8 may be used. When this sheet-like heat pipe is attached, the metal mesh layers 13 and 14 are provided opposite to each other with the spacer 3 interposed therebetween, so the surface to be attached may be either.

  Since the sheet-like heat pipe of the present invention can provide stable and high cooling performance without impairing flexibility, the sheet-like heat pipe can be used for cooling electronic devices in which a space for installing a heat radiating plate or a heat radiating fan cannot be secured in the heat generating portion.

It is a figure which shows the sheet-like heat pipe in Embodiment 1 of this invention, (a), (b) exploded perspective view, (c) A-A 'line sectional drawing of (a). It is a figure which shows the sheet-like heat pipe in Embodiment 2 of this invention, (a), (b) exploded perspective view, (c) B-B 'sectional view taken on the line of (a) Sectional drawing of the sheet-like heat pipe in Embodiment 3 of this invention Sectional drawing of the sheet-like heat pipe in Embodiment 4 of this invention Sectional drawing of the sheet-like heat pipe in Embodiment 5 of this invention Sectional drawing of the sheet-like heat pipe in Embodiment 6 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet 2 Adhesive film 3 Spacer 4 Sheet 5 Groove 6 Resin layer 7 Metal layer 8 Metal layer 9 Resin layer 10 Joint part 11 Steam flow path 12 Roughening surface 13 Metal mesh layer 14 Metal mesh layer

Claims (9)

A sheet-like container sealed with a sheet-like member facing and bonded together with a peripheral part, a wick layer that exerts a capillary force formed on the inner wall surface of the container, and a cut surface of a substantially cylindrical small piece cut from a metal wire A sheet-like heat pipe comprising: a plurality of spacers fixedly arranged at predetermined positions on the wick layer so as to be perpendicular to the inner wall surface of the container; and a working fluid sealed inside the container. . The sheet-like heat pipe according to claim 1, wherein the sheet-like member is a soft metal member or a composite material having at least a metal layer. The sheet-like heat pipe according to claim 1, wherein the metal wire is a stranded wire made of a fine metal wire. The sheet-like heat pipe according to any one of claims 1 to 3, wherein a diameter of the substantially cylindrical small piece is smaller than an axial length. The sheet-like heat pipe according to any one of claims 1 to 4, wherein the surface of the metal wire is covered with a solder alloy and fixed on the wick layer by solder bonding. The sheet-like heat pipe according to any one of claims 1 to 5, wherein the wick layer has a groove shape formed on the inner wall surface. The sheet-like heat pipe according to any one of claims 1 to 5, wherein the wick layer is a roughened surface layer formed by roughening the inner wall surface. The sheet-like heat pipe according to any one of claims 1 to 5, wherein the wick layer has a mesh shape formed on the inner wall surface. The sheet-like heat pipe according to any one of claims 1 to 5, wherein the wick layer is a metal mesh layer formed on the inner wall surface.

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