JP3956778B2 - Thin heat pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet-type heat pipe for efficiently cooling a highly heat-generating component such as a semiconductor, and particularly for efficiently cooling a semiconductor or the like mounted in a very thin casing.
[0002]
[Prior art]
In recent years, electronic devices have built-in high-power, highly-integrated parts such as microprocessors. Microprocessors have a very high degree of integration and perform processing such as calculation and control of information at high speed, so that a large amount of heat is released. Various cooling systems have been proposed for cooling chips and the like, which are high output and highly integrated parts. One typical cooling system is a heat pipe.
The heat pipe includes a round pipe-shaped heat pipe and a planar heat pipe. For cooling a component to be cooled of an electronic device such as a CPU, a flat heat pipe is preferably used because it can be easily attached to the component to be cooled and a wide contact surface can be obtained.
[0003]
Furthermore, the heat pipe is divided into a top heat mode in which the part to be cooled is located at the upper part and a bottom heat mode in which the part to be cooled is located in the lower part at the attachment position of the part to be cooled. In the bottom heat mode, the liquid recirculates due to gravity, but in the top heat mode, the liquid must be recirculated against gravity, and normally a capillary phenomenon due to wicking is used.
A space serving as a flow path for the working fluid is provided inside the heat pipe, and the working fluid accommodated in the space undergoes a phase change or movement such as evaporation or condensation, thereby transferring heat.
[0004]
The details of the heat pipe including a sealed cavity and in which heat is transferred by the phase transformation and movement of the working fluid contained in the cavity are as follows.
On the heat absorption side of the heat pipe, the heat generated by the part to be cooled that has been conducted through the material of the container that constitutes the heat pipe is absorbed as latent heat, the working fluid evaporates, and the vapor is dissipated from the heat pipe. Move to the side. On the heat radiating side, the working fluid vapor condenses to release latent heat and returns to the liquid phase. The working fluid that has returned to the liquid phase in this way moves (refluxs) again to the heat absorption side. Heat is transferred by such phase transformation and movement of the working fluid.
In a gravity heat pipe, the working fluid that has become a liquid phase by phase transformation moves (refluxs) to the heat absorption side by gravity.
[0005]
In recent years, housings on which the above-described chips and the like are mounted are becoming thinner and heat pipes are becoming thinner accordingly.
In a flat thin heat pipe, it is desirable to ensure a steam flow path linearly along the direction in which heat is to be transmitted, for example, along the longitudinal direction. However, when a container is formed using a metal foil that is thin enough to be easily deformed, the container is crushed from the outside by atmospheric pressure. FIG. 5 is a diagram showing a conventional mesh. In this mesh, the diameters and tensions of the vertical line 106 and the horizontal line 107 are equal, and the hole area ratio as viewed from the normal direction to the mesh surface is generally large. Simply inserting a mesh formed in this way into a container formed from a thin metal foil or the like that is easily deformed will cause crushing by atmospheric pressure, resulting in a very small gap, Steam flow path is not secured. Further, since the vertical gap and horizontal line are alternately in contact with the inner wall of the container in the remaining gap, a straight gap is not secured along the line, and the flow resistance of the steam is large.
[0006]
Therefore, when a thin metal foil is used as a container, a spacer is required as a support for maintaining the shape. Examples of conventional spacers include spot welding and embossing. However, these technologies require the rigidity of the container itself, and are not suitable for containers made of thin and soft metal foil. It was. In addition, if a spacer with a certain degree of rigidity is inserted into the container separately, the spacer may bend or the steam flow path may be blocked when the container is bent. Could not be requested.
Japanese Patent Application Laid-Open No. 2001-165854 discloses a sheet-like heat pipe (hereinafter referred to as “prior art”). In the prior art, a plurality of columnar spacers joined to a container are used.
[0007]
[Problems to be solved by the invention]
However, the prior art sheet heat pipe has the following problems.
In other words, the intervals between the columnar spacers are not uniform, and there may be variations in performance, resulting in poor reliability. Furthermore, since the columnar spacers are joined to the container by an adhesive or the like, non-condensable gas is generated inside the container, which may impair long-term reliability. Further, if the container body is bent, the joined columnar spacers may be peeled off from the container, and the performance may be deteriorated. Furthermore, individual differences for each product may increase. Furthermore, there is a problem that the number of members and the number of processes increase.
[0008]
Accordingly, an object of the present invention is to provide a thin heat pipe that can be used for efficiently cooling a heat generating electronic component such as a CPU mounted in a very thin casing.
[0009]
[Means for Solving the Problems]
The present inventor has intensively studied to solve the conventional problems described above. As a result, in a sealed container formed by joining the peripheral parts of two foil-like sheets, a mesh formed by vertical and horizontal lines of different diameters so as to increase the capillary force in a predetermined direction It has been found that by accommodating the slidable state in a movable state, it can be bent, a steam flow path in a predetermined direction can be secured without being crushed by the atmosphere, and the mesh can function as both a spacer and a wick. .
[0010]
Furthermore, in a sealed container formed by joining the peripheral portions of two foil-like sheets, it consists of vertical lines and horizontal lines having different diameters composed of stranded wires formed by a plurality of strands. By accommodating the mesh in a movable state, it is possible to bend, to easily secure a steam flow path along the heat transfer direction without being crushed by the atmosphere, and to obtain a capillary force inside the vertical line. It was found that the mesh can function as both a spacer and a wick.
[0011]
In addition, in a sealed container formed by joining the periphery of two foil-like sheets, a mesh with a high density of small diameter lines consisting of vertical and horizontal lines with different diameters is accommodated in a movable state. By doing so, it is possible to bend, and it is possible to easily secure a steam flow path along the heat transfer direction without being crushed by the atmosphere, and further increase the contact area between the container wall surface and the mesh to increase the capillary force It turns out that you can.
[0012]
The present invention has been made based on the above research results, and the first aspect of the thin heat pipe of the present invention is a hermetically sealed structure formed by joining the peripheral portions of the laminated foil-like sheets. container and is housed in a movable state within the container, vertical lines of different diameters and the mesh formed by the horizontal lines, and a working fluid sealed within the container, the diameter of the mesh is larger A thin heat pipe characterized by increasing the capillary force of the working fluid along a vertical line or a horizontal line .
[0013]
A second aspect of the thin heat pipe of the present invention is a thin heat pipe in which the mesh is made of a plain woven mesh having a vertical line diameter larger than a horizontal line diameter.
[0014]
According to a third aspect of the thin heat pipe of the present invention, there are a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets, and a plurality of containers accommodated in a movable state in the container. A thin heat pipe provided with a mesh composed of vertical lines and horizontal lines having different diameters formed of strands of wire and a working fluid sealed in the container.
[0015]
In a fourth aspect of the thin heat pipe of the present invention, the mesh is made of a woven mesh in which the diameter of the vertical line is larger than the diameter of the horizontal line, and the number of strands of the vertical line is larger than the number of strands of the horizontal line. Many thin heat pipes.
[0016]
The fifth aspect of the thin heat pipe of the present invention is a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets, and different diameters accommodated in the container in a movable state. The thin heat pipe is provided with a mesh composed of vertical lines and horizontal lines and having a high density of small diameter lines, and a working fluid sealed in the container.
[0017]
A sixth aspect of the thin heat pipe of the present invention is a thin heat pipe, wherein the mesh is a tatami woven mesh in which the diameter of the vertical line is larger than the diameter of the horizontal line and the density of the horizontal line is higher than the density of the vertical line. is there.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The aspect of the thin heat pipe of this invention is demonstrated in detail, referring drawings.
The thin heat pipe according to the present invention enhances the capillary force in a predetermined direction, which is enclosed in a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets and is movably accommodated in the container. A thin heat pipe including a mesh formed by vertical and horizontal lines having different diameters and a working fluid sealed in a container. The mesh mentioned above consists of a plain woven mesh in which the diameter of the vertical line is larger than the diameter of the horizontal line.
[0019]
In the thin heat pipe of the present invention, two foil-like sheets are overlapped, and the peripheral part is joined by a method such as seam welding or brazing to form a container. In the container, a mesh formed by vertical lines and horizontal lines having different diameters is accommodated in a movable state so as to increase the capillary force in a predetermined direction.
[0020]
FIG. 1 is a view for explaining a mesh used in the thin heat pipe of the present invention. As shown in FIG. 1, the mesh 5 of the present invention is a plain weave mesh using vertical lines 6 and horizontal lines 7 having different diameters. That is, the diameter of the vertical line is larger than the diameter of the horizontal line. The vertical line and the horizontal line are each composed of one wire. A mesh is formed by braiding a vertical line composed of a plurality of wires having a diameter of a predetermined size arranged in parallel so as to be wound in a wavy manner by a horizontal line having a diameter considerably smaller than the diameter of the vertical line. By increasing the difference between the diameter of the vertical line 6 and the diameter of the horizontal line 7, the vertical line 6 is not bent and maintains the original linear form, and the horizontal line 7 having a small diameter has a plurality of parallel vertical lines. A wire is wound around the line. As a result, as shown by the arrows in the drawing, it is possible to ensure a steam flow path in the direction along the axial direction of the vertical line.
[0021]
When the mesh formed in this way is accommodated in the above-described container in a movable state, even if the container is formed by a sheet of metal foil that is thin enough to be easily deformed,
The steam flow path is easily secured by a plurality of parallelly arranged vertical lines arranged in the longitudinal direction of the container without being blocked by the atmospheric pressure. Further, since the mesh described above is accommodated in the container in a movable state, even if the container is bent, no buckling occurs, and the heat pipe has flexibility.
[0022]
Even if the container is formed of a thin and soft foil-like sheet by appropriately adjusting the interval between the vertical lines arranged in parallel, the gap is linearly formed along the vertical line without being crushed by atmospheric pressure. Can be secured.
As described above, by using a mesh formed by combining two types of wires having different diameters, it is possible to secure a steam flow path and obtain excellent heat transport characteristics as an extremely thin heat pipe.
[0023]
As described above, the container is formed of a metal foil or the like that is thin enough to be bent in order to obtain flexibility. A container in which metal foils are joined by a method such as seam welding or brazing has high long-term reliability. In general, resins have been believed to have low reliability in terms of permeability, gas generation, and the like, but resin / clay at the nanocomposite level or composite materials such as resin / metal are conventional resins. There are examples in which the characteristics are drastically improved compared to the above, and these composite materials can also be used.
[0024]
Furthermore, the thin heat pipe of the present invention includes a hermetically sealed container formed by joining the peripheral portions of the overlapped foil-like sheets, and a plurality of strands that are housed in a movable state in the container. A thin heat pipe provided with a mesh composed of vertical lines and horizontal lines each having a different diameter formed of a stranded wire and a working fluid sealed in the container.
[0025]
In the thin heat pipe of the present invention, two foil-like sheets are overlapped, and the peripheral part is joined by a method such as seam welding or brazing to form a container. In the container, a mesh composed of vertical lines and horizontal lines having different diameters made of stranded wires formed by a plurality of strands is accommodated in a movable state. In other words, the mesh described above is a woven mesh in which the diameter of the vertical line is larger than the diameter of the horizontal line, and the number of strands of the vertical line is larger than the number of strands of the horizontal line.
[0026]
FIG. 2 is a view for explaining another embodiment of the mesh used in the thin heat pipe of the present invention. As shown in FIG. 2, the mesh 15 of the present invention is a mesh composed of vertical lines 16 and horizontal lines 17 having different diameters made of stranded wires formed by a plurality of strands. That is, the diameter of the vertical line 16 is larger than the diameter of the horizontal line 17. Note that the same wire is used for the vertical line and the horizontal line, and the diameter varies depending on the number of the wires. A mesh is formed by braiding a twisted wire formed of a plurality of strands around a vertical line arranged in parallel so as to be wound in a wavy manner by a horizontal line having a diameter considerably smaller than the diameter of the vertical line. For example, as shown in FIG. 2B, the vertical line 16 is made of a stranded wire formed by four strands 18, and the horizontal line is made of a stranded wire formed by two strands. . By increasing the difference between the diameter of the vertical line 16 and the diameter of the horizontal line 17, the vertical line 16 is not bent and maintains the original linear form, and the horizontal line 17 having a small diameter has a plurality of parallel vertical lines. A wire is wound around the line. As a result, as shown by the arrows in the drawing, it is possible to ensure a steam flow path in the direction along the axial direction of the vertical line.
In addition, according to this aspect, as shown in FIG.2 (b), capillary force can be acquired also inside a vertical line with the twisted wire which consists of a some strand.
[0027]
When the mesh formed in this way is accommodated in the above-described container in a movable state, even if the container is formed by a sheet of metal foil that is thin enough to be easily deformed,
The steam channel is not blocked by the atmospheric pressure, and the steam channel is easily formed by a plurality of parallelly arranged vertical lines (twisted strands) arranged in the longitudinal direction of the container. Secured. Furthermore, a capillary force can be obtained even inside the vertical line by a stranded wire composed of a plurality of strands. Further, since the mesh described above is accommodated in the container in a movable state, even if the container is bent, no buckling occurs, and the heat pipe has flexibility.
[0028]
In addition, even if the container is formed of a thin and soft foil-like sheet by appropriately adjusting the interval between the vertical lines arranged in parallel, the vertical lines (consisting of a plurality of strands are not crushed by the atmospheric pressure. The gap can be ensured linearly along the stranded wire.
As described above, by using a mesh composed of vertical wires 16 and horizontal wires 17 having different diameters composed of stranded wires formed by a plurality of strands, a steam flow path is secured and excellent as an extremely thin heat pipe. Heat transport properties can be obtained.
[0029]
Furthermore, the thin heat pipe of the present invention includes a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets, and vertical lines of different diameters that are movably accommodated in the container. It is a thin heat pipe provided with a mesh composed of horizontal lines and a high density of small diameter lines and a working fluid sealed in a container. The mesh described above is a tatami mesh.
[0030]
FIG. 3 is a diagram for explaining another embodiment of the mesh used in the thin heat pipe of the present invention. As shown in FIG. 3, the mesh 25 of the present invention is a tatami mesh using vertical lines 26 and horizontal lines 27 having different diameters. That is, the difference between the diameters of the vertical line and the horizontal line is small, and the diameter of the vertical line is slightly larger than the diameter of the horizontal line. The vertical line and the horizontal line are each composed of one wire. A mesh is formed by weaving around a vertical line composed of a plurality of wires having a diameter of a predetermined size arranged in parallel so as to be wound in a wave shape by a horizontal line having a diameter slightly smaller than the diameter of the vertical line. . In this embodiment, the density of horizontal lines is high and the flow of steam in the horizontal direction is also strong. Therefore, a steam flow path can be secured along the direction of the vertical line and the direction of the horizontal line.
According to the tatami mesh formed in this way, the capillary force can be increased by increasing the contact area between the wall surface of the container and the mesh.
[0031]
When the mesh formed in this way is accommodated in the above-described container in a movable state, even if the container is formed by a sheet of metal foil that is thin enough to be easily deformed,
The steam flow path is easily secured along the vertical line arranged in the longitudinal direction of the container and the horizontal line arranged in the width direction of the container without being blocked by the atmospheric pressure. Further, since the mesh described above is accommodated in the container in a movable state, even if the container is bent, no buckling occurs, and the heat pipe has flexibility.
[0032]
As mentioned above, by using a mesh formed by combining vertical and horizontal lines with slightly different diameters and increasing the density of the horizontal lines, a steam flow path is secured and excellent heat as an extremely thin heat pipe. Transport properties can be obtained.
FIG. 4 is a diagram for explaining a state in which the mesh of the aspect shown in FIG. 1 is accommodated in a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets. As shown in FIG. 4, in the sealed container formed by joining the peripheral portions 4 of the two foil-like sheets 2 and 3 overlapped by seam welding or ultrasonic welding, the longitudinal direction of the container The mesh 5 formed by the large-diameter vertical line 6 and the small-diameter horizontal line 7 is accommodated in a movable state so as to increase the capillary force.
[0033]
As a material for the container of the planar heat pipe, a metal having good heat conduction such as copper (C1020, C1100, C1200), aluminum (A1010 A1100 A5000 series, A6000 series, A7000 series) is used. When the clad material is used, a dissimilar metal such as aluminum / copper or copper / ceramics (alumina, beryllia, aluminum nitride, copper tungsten) can be used. The shape of the planar heat pipe can be various shapes such as a circular cross section, an elliptical shape, and a rectangular shape.
As the working fluid sealed in the sealed cavity, water, alternative chlorofluorocarbon, florina, cyclopentane, or the like is used according to the compatibility with the container material.
[0034]
As described above, in the thin heat pipe of the present invention, from a plain woven mesh formed by vertical lines and horizontal lines having different diameters so as to increase the capillary force in a predetermined direction, from a stranded wire formed by a plurality of strands. A woven mesh composed of vertical and horizontal lines of different diameters, and a tatami mesh formed by vertical and horizontal lines where the vertical line diameter is larger than the horizontal line diameter and the horizontal line density is higher than the vertical line density. Only by inserting it into the container, a steam flow path along the heat transfer direction can be easily secured without using other spacers. Furthermore, after deaeration, the container is pressed against the mesh by atmospheric pressure, so that the mesh is fixed in the container and the adhesion between the mesh and the inner wall of the container is good, and as a result, a high capillary force is obtained.
[0035]
【The invention's effect】
As described above, according to the present invention, without using a spacer, it is prevented from being collapsed by atmospheric pressure, has a good capillary force, is thin, flexible, has a large amount of heat transport, and has a thin high performance. A sheet-like heat pipe can be provided.
Furthermore, it is possible to provide a thin heat pipe that can be used to efficiently cool a heat generating electronic component such as a CPU mounted in an extremely thin casing.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a mesh used in a thin heat pipe of the present invention.
[Fig. 2] Fig. 2 is a diagram for explaining another embodiment of the mesh used in the thin heat pipe of the present invention.
[Fig. 3] Fig. 3 is a diagram for explaining a mesh of another aspect used in the thin heat pipe of the present invention.
4 is a view for explaining a state in which the mesh of the aspect shown in FIG. 1 is housed in a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets. FIG.
FIG. 5 is a diagram showing a conventional mesh.
[Explanation of symbols]
1. 1. Thin heat pipe 2. Foil-like sheet 3. Foil-like sheet 4. Peripheral part Mesh 6. 6. Plain weave vertical line 15. Plain weave horizontal line Mesh 16. 18. Vertical line made of stranded wire Horizontal wire made of stranded wire 18. Wire 25. Mesh 26. Tatami vertical line 27. Tatami weave horizontal line

Claims (6)

And superimposed foil-like sheet sealed container formed by joining the peripheral portion of the are housed in a movable state in the front container, main formed by the horizontal and vertical lines of different diameters Mesh And a working fluid sealed in the container, and the capillary force of the working fluid is increased along the vertical line or horizontal line where the diameter of the mesh is large . The thin heat pipe according to claim 1, wherein the mesh is a plain woven mesh having a vertical line diameter larger than a horizontal line diameter. Different diameters consisting of a sealed container formed by joining the peripheral portions of the overlapped foil-like sheets and a stranded wire formed by a plurality of strands housed in the container in a movable state A thin heat pipe provided with a mesh composed of vertical and horizontal lines and a working fluid sealed in the container. The thin heat pipe according to claim 3, wherein the mesh is made of a woven mesh in which the diameter of the vertical line is larger than the diameter of the horizontal line, and the number of strands of the vertical line is larger than the number of strands of the horizontal line. The density of a small diameter line consisting of a sealed container formed by joining the peripheral parts of the overlapped foil-like sheets, and vertical and horizontal lines of different diameters accommodated in a movable state in the container. A thin heat pipe comprising a high mesh and a working fluid sealed in the container. The thin heat pipe according to claim 5, wherein the mesh is made of a tatami woven mesh having a vertical line diameter larger than a horizontal line diameter and a horizontal line density higher than the vertical line density.

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