JP2012154622A - Thin heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elliptical heat pipe having an excellent capillary force without blocking a vapor channel.SOLUTION: A shaft 12 which is provided with a notch 15 of a predetermined shape is longitudinally inserted into a tubular container 10, metal powder is filled into a space formed of the notch 15 and the inner wall of the tubular container 10, and the metal powder is heated to form a sintered metal. Then, the shaft 12 is pulled out, and elliptically processing is performed so that the sintered metal is positioned at the center of the tubular container 10.

Description

  The present invention relates to a heat pipe for cooling a cooled object such as a CPU housed in a personal computer, an electronic device or the like, for example, a heating element, a heat transfer body, etc., and a thin heat pipe having a large heat transport amount.

  In recent years, electrical devices such as personal computers have been remarkably reduced in size and performance, and there has been a strong demand for downsizing and space saving of a cooling mechanism for cooling a heat-generating component such as an MPU mounted thereon. The MPU has an extremely high degree of integration and performs processing such as calculation and control at a high speed, and thus releases a large amount of heat. Various cooling systems have been proposed to cool chips and the like, which are high-speed, high-output, highly integrated parts. One typical cooling system is a heat pipe.

  The heat pipe has an apparent thermal conductivity that is several times to several tens of times higher than that of a metal such as copper or aluminum, and is therefore used in various heat-related devices as a cooling element.

  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. With the downsizing and space saving of the cooling mechanism, in the case of a cooling mechanism using a heat pipe, it is also required to make the heat pipe thinner.

  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 heat is moved by the phase change or movement of the working fluid accommodated in the space such as evaporation and condensation. The details of the operation of the heat pipe having a sealed cavity and in which heat is transferred by 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.

  In the conventional thin heat pipe processing technology, additional processing is performed after heat pipe processing is performed with a combination of groove tube, bare tube and mesh, bare tube and braided wire, bare tube and sintered metal, bare tube and Fine Fiber Wicks, etc. As a result, flattening (for example, a thickness of about 2.0 mm to 4.0 mm in the case of a heat pipe of φ3 to φ6) has been performed.

JP 2004-198096 A

  As described above, the conventional heat pipe (2.0 mm to 4.0 mm) flattened after heat pipe processing cannot withstand the recent high heat generation of CPUs and the like. This is due to the lack of capillarity of the internal wick and the blockage of the steam flow path due to flattening.

  When the groove tube is flattened, the flow area in the tube is reduced, and the capillary force is reduced, so that the maximum heat transport amount is also reduced. There are two types of clogging of the steam flow path, one is a decrease in internal volume due to flattening as a whole, and the other is flattening when the amount of flattening increases (the heat pipe becomes thinner). This is a phenomenon in which the central portion of the heat pipe is recessed and the steam flow path is blocked.

  Thus, in the heat pipe in which the center part is dented, the adhesion degree of the joint part to the CPU and the heat radiating part is deteriorated, resulting in a large thermal resistance and a poor cooling effect. In addition, in the internal structure of the heat pipe, the space through which the working fluid flows becomes narrower than the intended space, so that a desired cooling effect cannot be obtained.

  Accordingly, an object of the present invention is to solve the conventional problems and provide a flat heat pipe having an excellent capillary force without blocking the steam flow path.

The present inventor has intensively studied to solve the conventional problems described above. As a result, first, a core rod having one notch part having a predetermined shape is inserted into the tubular container along the long axis, and a metal is formed in the space formed by the notch part and the inner wall of the container. Fill powder and heat to form sintered metal. After that, when the core rod is pulled out and flattened so that the sintered metal is positioned at the center of the container, the sintered metal is in thermal contact with the flat portion inside the container, and the curved portions on both sides of the container It has been found that a flat heat pipe having an excellent capillary force can be obtained without clogging the steam flow path because the gap is provided in the tube.

Furthermore, when a core rod having a pair of notches symmetrical along the long axis is inserted into a tubular container, it is heated to form a sintered metal, and the core rod is drawn and fired. When flattening is performed so that the sintered metal is located on the curved portions on both sides of the container, the sintered metal is packed in the curved portions on both sides of the container, and a gap is provided in the flat portion of the container, so securing a steam flow path, In addition to excellent capillary force, it has been found that buckling does not occur when bending is performed.

The present invention has been made based on the above research results, and a first aspect of the thin heat pipe of the present invention includes a sealed flat container,
A sintered metal formed on a part of the inner wall of the container;
A working fluid enclosed in the container;
Is a thin heat pipe .

According to a second aspect of the thin heat pipe of the present invention, in the first aspect of the thin heat pipe, the sintered metal is disposed on a flat portion of the container in contact with upper and lower inner walls. It is a thin heat pipe characterized by

A third aspect of the thin heat pipe of the present invention is the thin heat pipe according to the first aspect of the thin heat pipe, wherein the sintered metal is disposed in curved portions on both sides of the container. It is a pipe .

According to a fourth aspect of the thin heat pipe of the present invention, in any one of the first to third aspects of the thin heat pipe, the sintered metal has a rectangular or trapezoidal cross section. It is a thin heat pipe .

According to a fifth aspect of the thin heat pipe of the present invention, in any one of the first to fourth aspects of the thin heat pipe, the sintered metal is formed by heating metal powder in the container. It is a thin heat pipe characterized by being a thing .

According to one aspect of the present invention, since the wick formed of sintered metal on the flat portion portion of the inner wall of the flat processed container in contact with the heat source is in thermal contact with the heat density becomes small, efficient Heat transfer. Bend portion of the container sides not in contact with the heat source becomes a void portion, the steam flow path can be secured sufficiently.
Furthermore, according to another aspect of the present invention, the curved portions on both sides of the flattened container are filled with wicks made of sintered metal, so that a steam flow path is ensured in the central portion, and an excellent capillary tube In addition to providing a force, it is resistant to bending and can be prevented from buckling when it is bent.

FIG. 1 is a schematic view for explaining a method for manufacturing a thin heat pipe according to the present invention. FIG. 1A is a perspective view showing a tube-shaped container. FIG.1 (b) is a perspective view which shows the core rod provided with the notch part. FIG. 2 is a cross-sectional view illustrating a state in which a core rod having a notch is inserted into a tubular container. FIG. 3A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. FIG. 3B is a schematic cross-sectional view for explaining a state in which the container in which the sintered metal is formed is flattened. FIG. 4 is a schematic diagram for explaining a method for manufacturing a thin heat pipe according to the present invention. FIG. 4A is a perspective view showing a tubular container. FIG.4 (b) is a perspective view which shows the core bar provided with the notch part. FIG. 5 is a cross-sectional view illustrating a state in which a core bar having a pair of symmetrical notches is inserted into a tubular container. FIG. 6A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. FIG. 6B is a schematic cross-sectional view illustrating a state in which flattening is performed on a container in which a pair of symmetrical sintered metals are formed inside. FIG. 7 is a cross-sectional view illustrating a container having a groove structure on the inner wall. FIG. 8A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. FIG. 8B is a schematic cross-sectional view illustrating a state in which a container in which a pair of sintered metals symmetrical in the vertical direction is formed is flattened from the vertical direction.

The thin heat pipe of the present invention and the manufacturing method thereof will be described in detail with reference to the drawings.
One method of manufacturing the thin heat pipe of this invention is to prepare a tube-shaped container,
Insert a core rod having a notch of a predetermined shape along the long axis direction into the container,
Filling the space formed by the notch and the inner wall of the container with metal powder,
Heating the container with the metal powder and the core rod inserted, and sintering the metal powder to form a sintered metal;
Pull out the core rod from the container,
The container is flattened,
It is a manufacturing method of a thin heat pipe which manufactures by enclosing a working fluid in the container.

  FIG. 1 is a schematic view for explaining a method for manufacturing a thin heat pipe according to the present invention. FIG. 1A is a perspective view showing a tube-shaped container. FIG.1 (b) is a perspective view which shows the core rod provided with the notch part. As shown in FIG. 1A, a tube-shaped container 10 having a substantially cylindrical shape is prepared. As shown in FIG. 1B, a bottom surface 13 and both side surfaces 14 along a major axis are formed on a part of a cylindrical core rod 12 which can be inserted into an inner wall 11 of a tube-shaped container 10 with almost no gap. The notch part 15 provided with is formed. The core rod 12 with the notch formed in this way is inserted into the tube-shaped container 10. At this time, as described above, the outer peripheral surface 16 of the core rod 12 and the inner peripheral surface 11 of the container 10 are in contact with each other with almost no gap, and the core rod 12 is inserted into the container 10.

  As described above, when the core rod is inserted into the container, the cross section is substantially rectangular or trapezoidal depending on the bottom surface and both side surfaces formed on the core rod and the inner wall of the container along the long axis direction of the container. The so-called saddle-shaped one long and narrow space is formed.

  FIG. 2 is a cross-sectional view illustrating a state in which a core rod having a notch is inserted into a tubular container. As shown in FIG. 2, a cylindrical core rod 12 having a notch 15 is inserted in a state where there is almost no gap between the inner wall 11 of the cylindrical container 10. The notch 15 is formed of a recess having, for example, a bottom surface 13 and a side surface 14, and a substantially trapezoidal space section is formed by the inner wall 11 of the cylindrical container 10 and the notch 15. . As described above, the space portion of this aspect is composed of one long and narrow space portion having a substantially rectangular or trapezoidal cross section.

  As described above, a metal powder is filled in a long and narrow space portion formed by inserting a cylindrical core rod having a notch into a cylindrical container. The material of the metal powder is, for example, bronze, stainless steel, etc., and the shape of the material is spherical powder or irregular shaped powder. By adjusting the size of the metal powder, the voids of the sintered metal described later Can be adjusted.

  In a state in which the cross-section is substantially rectangular or substantially trapezoidal in the shape of a bowl-shaped elongated space filled with metal powder, it is heated at a predetermined temperature, that is, a temperature before and after the melting point of the metal powder, A sintered metal is formed. Sintered metal is formed in a state where metal powders are connected to each other. Since the sintered metal is formed in a state where the metal powders are connected to each other as described above, an acute angle portion having a strong capillary force is formed throughout, thereby facilitating the movement of the working fluid.

Next, the core rod is pulled out from the inside of the container. FIG. 3A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. As shown in FIG. 3 (a), when the withdrawal of the mandrel from the container, sintered metal 17 formed in a space portion formed by the notches and the container inner wall of the core rod, the inner wall of the container 10 11 is left in contact. That is, along the longitudinal direction of the container, a saddle-like elongated sintered metal having a substantially rectangular or substantially trapezoidal cross section is formed in contact with the inner wall of the cylindrical container.

FIG. 3B is a schematic cross-sectional view for explaining a state in which the container in which the sintered metal is formed is flattened. As shown in FIG. 3A, along the longitudinal direction, a container in which a saddle-like elongated sintered metal having a substantially rectangular or trapezoidal cross section is in contact with the inner wall of a cylindrical container. When a force is applied as shown by an arrow f1 and the container is flattened, as shown in FIG. 3B, the sintered metal 17 is positioned on the horizontal portion 19 of the container 10, and the curves on both sides of the container 10 are curved. Each of the portions 18 is opened as a gap and secured as a vapor flow path for the working fluid. A thin fluid pipe is formed by enclosing a working fluid in the flat container thus formed.

The flat portion 19 at the center of the flattened container is required to have flatness in order to be thermally connected to a heat source.
In the thin heat pipe of this aspect, since the wick formed of the sintered metal 17 is in thermal contact with the entire flat portion 19 of the inner wall of the flattened container that is in contact with the heat source, the heat density is reduced. In addition, the sintered metal 17 has a large number of acute angle portions throughout, and has a strong capillary force, facilitates the movement of the working fluid, and enables efficient heat transfer. Furthermore, as described above, the curved portions 18 on both sides of the container not in contact with the heat source become a gap portion in the entire length direction, and a sufficient steam flow path can be secured.

  One aspect of the thin heat pipe of the present invention is a thin heat pipe manufactured by one aspect of the thin heat pipe manufacturing method of the present invention described above. This will be described with reference to FIG. That is, in one aspect of the thin heat pipe of the present invention, an airtight flat container 10 formed by pressing and deforming a tubular molded product and a core rod having a notch portion having a predetermined shape are inserted into the tubular molded product. The space formed by the notch and the inner wall of the tubular molded product is filled with metal powder, the tubular molded product is heated with the metal powder and the core rod inserted, and the core rod is pulled out from the tubular molded product. It is a thin heat pipe provided with the sintered metal 17 formed and disposed in contact with the inner wall of the flat container by pressing deformation, and the working fluid sealed in the flat container 10. Sintered metal 17 is disposed in a flat portion 19 at the center of the container in contact with the upper and lower inner walls, and voids are formed in the curved portions 18 on both sides of the container.

Another method of manufacturing the thin heat pipe of the present invention differs from the method described with reference to FIGS. 1 to 3 in the following features. That is, the space part formed by the above-mentioned notch part and the inner wall of a container consists of a symmetrical pair of ridge shape provided with the bottom face and both sides | surfaces formed along the major axis direction of the cylindrical core rod. ing. Further, the flattening of the container is performed so that the sintered metal is located at the curved portions on both sides of the container.

FIG. 4 is a schematic diagram for explaining a method for manufacturing a thin heat pipe according to the present invention.
FIG. 4A is a perspective view showing a tubular container. FIG.4 (b) is a perspective view which shows the core bar provided with the notch part. As shown in FIG. 4A, a tube-shaped container 20 having a substantially cylindrical shape is prepared. As shown in FIG. 4B, a bottom surface 23 and both side surfaces 24 along the long axis are formed on a part of a cylindrical core rod 22 that can be inserted into the inner wall 21 of the tubular container 20 with almost no gap. A pair of symmetrical notches 25 is formed. The core rod 22 formed with the pair of symmetrical notches 25 is inserted into the tubular container 20. At this time, as described above, the outer peripheral surface 26 of the core rod 22 and the inner peripheral surface 21 of the container 20 are in contact with each other with almost no gap, and the core rod 22 is inserted into the container 20.

  As described above, when the core rod is inserted into the container, a pair of symmetrical cross-sections are formed by the bottom surface and both side surfaces formed on the core rod and the inner wall of the container along the major axis direction of the container. A long and narrow space having a substantially rectangular or substantially trapezoidal bowl shape is formed.

  FIG. 5 is a cross-sectional view illustrating a state in which a core bar having a pair of symmetrical notches is inserted into a tubular container. As shown in FIG. 5, a cylindrical core rod 22 having a pair of symmetrical notches 25 is inserted in a state where there is almost no gap between the inner wall 21 of the cylindrical container 20. The pair of symmetrical cutouts 25 are each formed of a recess having, for example, a bottom surface 23 and a side surface 24, and the cross section is substantially trapezoidal due to the inner wall 21 of the cylindrical container 20 and the cutout portion 25. A space is formed. As described above, the space portion in this aspect is composed of a pair of symmetrical long and narrow space portions.

  As described above, each of the elongate and narrow space portions formed by inserting a cylindrical core rod having a notch into a cylindrical container is filled with metal powder. The material of the metal powder is, for example, bronze, stainless steel, or the like, as described with reference to FIGS. 1 to 3, and the shape of the material is spherical powder or deformed powder. It is possible to adjust the voids of the sintered metal, which will be described later, by adjusting the size of.

  Heating at a predetermined temperature, that is, a temperature around the melting point of the metal powder, in a state where each of the elongate space portions having a substantially rectangular or trapezoidal cross section is filled with the metal powder, is in contact with a part of the inner wall of the container. To form a sintered metal. Sintered metal is formed in a state where the contact points of metal powders are connected. Since the sintered metal is formed in a state in which the contact points of the metal powders are connected as described above, an acute angle portion having a strong capillary force is formed throughout, thereby facilitating movement of the working fluid.

  Next, the core rod is pulled out from the inside of the container. FIG. 6A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. As shown in FIG. 6A, when the core rod is pulled out from the container, the sintered metal 27 formed in a pair of symmetrical spaces formed by the notch portion of the core rod and the inner wall of the container The container 20 is left in contact with the inner wall 21 of the container 20. That is, along the longitudinal direction of the container, a pair of symmetrical saddle-shaped elongated sintered metals are formed in contact with the inner wall of the cylindrical container.

FIG. 6B is a schematic cross-sectional view illustrating a state in which flattening is performed on a container in which a pair of symmetrical sintered metals are formed inside. As shown in FIG. 6 (a), an arrow f2 is formed on the container formed with the saddle-like elongated sintered metal in contact with the inner walls of both ends in the horizontal direction of the cylindrical container along the longitudinal direction. When a force is applied as shown in FIG. 6 to flatten the container, as shown in FIG. 6B, the sintered metal 27 is positioned on the curved portions on both sides of the container 20, and the horizontal portion 29 of the container 20 is It is opened as a gap and secured as a vapor flow path for the working fluid. A thin fluid pipe is formed by enclosing a working fluid in the flat container thus formed.

  Further, in another aspect, a cylindrical core rod having a notch portion at the top and the bottom is inserted, and a metal powder is filled in each of the elongated space portions of the notch portion. It is heated at a temperature around the melting point to contact a part of the inner wall of the container to form a sintered metal (although not shown, it is generally the same as described with reference to FIGS. 2 and 5). Next, the core rod is pulled out from the inside of the container. In this way, the space formed by the notch and the inner wall of the container is formed as a pair of space portions that are substantially symmetrical with respect to the long axis of the core rod. FIG. 8A is a schematic cross-sectional view illustrating a state in which the core rod is pulled out from the inside of the container and a sintered metal is formed inside. As shown in FIG. 8 (a), when the core rod is pulled out from the container, the sintered metal is formed in a pair of symmetrical spaces formed by the upper and lower cutout portions of the core rod and the inner wall of the container. 47 is left in contact with the inner wall 41 of the container 40. That is, along the longitudinal direction of the container, a so-called bowl-shaped elongated sintered metal having a pair of symmetrical cross sections that are substantially rectangular or substantially trapezoidal is formed in contact with the inner wall of the cylindrical container.

  FIG. 8B is a schematic cross-sectional view illustrating a state in which a container in which a pair of sintered metals symmetrical in the vertical direction is formed is flattened from the vertical direction. As shown in FIG. 8 (a), an arrow f4 is formed on the container formed with the saddle-like elongated sintered metal in contact with the inner walls of both ends in the vertical direction of the cylindrical container along the longitudinal direction. As shown in FIG. 8, when the container is flattened by applying force, the sintered metal 47 is integrated and positioned at the center of the container 40 as shown in FIG. The curved portion 48 is opened as a gap portion, and is secured as a vapor flow path for the working fluid. A thin fluid pipe is formed by enclosing a working fluid in the flat container thus formed.

In the embodiment of the thin heat pipe of the present invention described with reference to FIGS. 1 to 3 and FIGS. 4 to 6, a cylindrical tube having no undulations is used as a container, but a capillary structure such as a groove is formed on the inner wall. A provided tube may be used. FIG. 7 is a cross-sectional view illustrating a container having a groove structure on the inner wall. As shown in FIG. 7, many fine grooves are formed on the inner wall portion of the container 30. Even if the cylindrical pipe having the capillary structure 31 such as the groove is provided on the inner wall as described above, the thin heat pipe of the present invention described with reference to FIGS. 1 to 3 and FIGS. 4 to 6 can be manufactured. Good. As a result, the capillary force of the container can be further improved.

  As described above, according to the present invention, it is possible to secure a wick portion having an excellent capillary force that moves the liquid phase and a sufficient gap serving as a steam flow path, and the heat absorbing portion is above the heat radiating portion. Even in some cases, a thin heat pipe having a large amount of heat transport can be obtained.

10, 20, 30, 40 Container 11, 21, 41 Container inner wall 12, 22 Core rod 13, 23 Bottom surface 14, 24 Side surface 15, 25 Notch 16, 26 Outer surface 17, 27, 47 Sintered metal 18, 28, 48 Curved portion 19, 29, 49 Flat portion 31 of container Capillary structure

Claims (5)

A sealed flat container,
A sintered metal formed on a part of the inner wall of the container;
A working fluid enclosed in the container;
Thin heat pipe with The thin heat pipe according to claim 1, wherein the sintered metal is disposed on a flat portion of the container so as to be in contact with upper and lower inner walls . The thin heat pipe according to claim 1, wherein the sintered metal is disposed in curved portions on both sides of the container . The thin heat pipe according to any one of claims 1 to 3, wherein the sintered metal has a rectangular or trapezoidal cross section . The thin heat pipe according to any one of claims 1 to 4, wherein the sintered metal is formed by heating metal powder in the container .

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