JP2014044031A - Heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pipe which is formed by enclosing a working medium in a sealed pipe container and has a structure where a metal layer forming an inner layer of a side wall of the container and containing copper is not easily peeled during processing.SOLUTION: A heat pipe 100 is formed by a sealed pipe and includes: a container 101 having a first end part and a second end part; and a working medium 102 held in the container 101. The working medium 102 evaporated at the first end part 101a is condensed in the second end part 101b thereby transferring heat from the first end part 101a to the second end part 101b. An inner layer 104 of the side wall 103 of the container is formed by a first metal containing copper, and an outer layer 105 is formed by a second metal containing aluminum. A layer 106 formed by an intermetallic compound is provided between the inner layer 104 and the outer layer 105.

Description

  The present invention relates to a heat pipe that transports heat as latent heat of a working medium.

  The heat pipe is obtained by enclosing a working medium in a pipe-like container sealed by exhausting non-condensable gas such as air. Usually, a wick serving as a flow path for the working medium is provided on the inner surface of the container.

  The heat pipe container is formed using a material having high thermal conductivity such as aluminum. Moreover, as a working medium for heat pipes, for example, water having a large latent heat is used. It is known that the heat transport amount of the heat pipe is increased by such a configuration.

  In Patent Document 1, as shown in FIG. 8, a sealed aluminum container 205 in which a working medium 202 is enclosed, a copper coating layer 204 formed by sintering or spraying copper fine particles on the inner wall surface thereof, The heat pipe 200 comprised by this is disclosed. However, when the shape of the heat pipe 200 having such a configuration is processed in accordance with the application, the coating layer 204 may be peeled off. In this case, when the side wall of the container 205 exposed in the peeled portion is in contact with the working medium 202, a battery is formed between the metal elements contained in the container 205 and the coating layer 204, and the side wall of the container 205 is The heat pipe 200 may be broken due to corrosion.

Japanese Patent Laid-Open No. 11-304381

  The present invention has been made in consideration of the above points, and a metal layer containing copper, which is formed by enclosing a working medium in a sealed pipe-shaped container and constituting the inner layer of the side wall of the container, is provided. An object of the present invention is to provide a heat pipe having a structure that is difficult to peel off during processing.

  A heat pipe according to claim 1 of the present invention is a sealed pipe, and includes a container having a first end and a second end, and a working medium held in the container. The working medium evaporated at one end is condensed at the second end to transfer heat from the first end to the second end, and is an inner layer of the side wall of the container. Is constituted by a first metal containing copper, an outer layer is constituted by a second metal containing aluminum, and a layer constituted by an intermetallic compound is provided between the inner layer and the outer layer. To do.

  In the configuration of the heat pipe according to the first aspect, the copper contained in the first metal layer and the aluminum contained in the second metal layer are firmly bonded via the intermetallic compound. Therefore, when processing the shape of the heat pipe, the layer of the first metal containing copper is difficult to peel from the side wall of the container. Therefore, according to the configuration of the heat pipe according to claim 1, the second metal layer containing aluminum is exposed to the working medium as the first metal layer is peeled off, and is dissolved into the working medium. By generating hydrogen, it is possible to prevent the heat pipe from being broken.

  The heat pipe according to claim 2 of the present invention is characterized in that, in claim 1, the layer made of the intermetallic compound contains aluminum and copper.

  According to the structure of Claim 2, it becomes a structure where the continuity in the interface of a metal compound and a 1st metal and the interface of a metal compound and a 2nd metal is high, and the 1st metal and 2nd metal through an intermetallic compound Can be made stronger.

  The heat pipe according to claim 3 of the present invention is characterized in that in claim 1 or 2, the heat pipe further includes a wick made of a third metal containing copper inside the side wall.

  According to the configuration of claim 3, the surface area of the working medium in the container is increased by the amount in contact with the wick. For this reason, the surface tension of the working medium increases, and the reflux of the working medium to the heating unit can be promoted by the capillary action generated due to the surface tension.

  In the configuration of the heat pipe according to the present invention, copper contained in the first metal layer and aluminum contained in the second metal layer are firmly bonded via the intermetallic compound. Therefore, when processing the shape of the heat pipe, the layer of the first metal containing copper is difficult to peel from the side wall of the container. Therefore, according to the configuration of the heat pipe according to claim 1, the second metal layer containing aluminum is exposed to the working medium as the first metal layer is peeled off, and is dissolved into the working medium. By generating hydrogen, it is possible to prevent the heat pipe from being broken.

It is a figure which shows the structure of the heat pipe of this invention typically. It is a figure which shows the structure of the heat pipe of this invention typically. It is a process flow for manufacturing the heat pipe of the present invention. It is a figure which shows typically the structure of the heat pipe in a manufacturing process. It is a figure which shows typically the structure of the heat pipe in a manufacturing process. It is a figure which shows typically the structure of the heat pipe in a manufacturing process. It is a photograph which expands and shows the composition of the heat pipe of the present invention. It is a figure which shows the structure of the conventional heat pipe typically.

  Hereinafter, based on a preferred embodiment, the present invention will be described with reference to the drawings. The following embodiments are described by way of example in order to better understand the gist of the invention, and do not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, the main part may be enlarged for convenience, and the dimensional ratios of the respective components are the same as the actual ones. Not necessarily.

<First embodiment>
[Configuration of heat pipe]
The structure of the heat pipe 100 which concerns on 1st embodiment of this invention is demonstrated using Fig.1 (a)-(c). FIG. 1A is a perspective view showing an outline of the heat pipe 100. The heat pipe 100 is a sealed pipe, and includes a container (container) 101 having a first end portion 101a and a second end portion 101b, and a working medium (FIG. 1B, ( c). In the present embodiment, a cylindrical heat pipe will be described below as an example. However, the heat pipe may have any shape that can enclose a working medium, for example, a shape surrounded by a plane. It may be a (planar) heat pipe.

  FIG. 1B is a cross-sectional view of the heat pipe 100 cut along a diameter direction (short direction) S along the line AA in FIG. FIG. 1C is a cross-sectional view of the heat pipe 100 cut perpendicularly to the axial direction (longitudinal direction) L along the line BB in FIG. The heat pipe 100 has a function of performing heat transfer from the first end 101a to the second end 101b by condensing the working medium 102 evaporated at the first end 101a at the second end 101b.

  As shown in FIGS. 1B and 1C, the heat pipe 100 is a heat pipe in which a working medium 102 is sealed in a sealed container 101. Of the side wall 103 of the container 101, the inner layer 104 is made of a first metal containing copper (Cu), and the outer layer 105 is made of a second metal containing aluminum (Al). Between the outer layer 105 and the inner layer 104 constituting the side wall, a layer 106 made of an intermetallic compound is provided.

  The first metal contains copper at a ratio of 99.9 [%] or more. The second metal contains aluminum at a rate of 99 [%] or more. An intermetallic compound is a compound formed by metal bonding of a first metal and a second metal.

  The working medium (working fluid) 102 is for heat transporting the heat applied to the first end 101a of the heat pipe to the second end 101b. As the working medium 102, for example, pure water that has a large latent heat and is environmentally friendly can be used.

  As described above, in the configuration of the heat pipe according to the first embodiment, the copper contained in the first metal layer and the aluminum contained in the second metal layer are firmly bonded via the intermetallic compound. Has been. Therefore, when processing the shape of the heat pipe, the layer of the first metal containing copper is difficult to peel from the side wall of the container. Therefore, according to the configuration of the heat pipe according to the first embodiment, as the first metal layer is peeled off, the second metal layer containing aluminum is exposed to the working medium and melts into the working medium. By generating hydrogen, it is possible to prevent the heat pipe from being broken.

<Modification 1>
Modification 1 of the heat pipe 100 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically illustrating the configuration of the heat pipe 110 according to the first modification. As shown in FIG. 2, the heat pipe 110 includes a wick 117 made of a metal containing copper inside the side wall 113.

  Similarly to the heat pipe 100 shown in FIG. 1, the heat pipe 110 is a heat pipe in which a working medium 112 is sealed in a sealed container 111. Out of the side walls 113 of the container 111, the inner layer 114 is made of a first metal containing copper (Cu), and the outer layer 115 is made of a second metal containing aluminum (Al). Between the outer layer 115 and the inner layer 114 of the sidewall, a layer 116 made of an intermetallic compound is provided.

  According to the configuration of Modification 1 described above, the surface area of the working medium 112 in the container 111 is increased by the amount in contact with the wick 117. Therefore, the surface tension of the working medium 112 increases, and the reflux of the condensed working medium 112 to the heating part (first end 101a) can be promoted by the capillary action generated due to the surface tension.

[Method of manufacturing heat pipe]
FIG. 3 shows a flow of steps included in the method of manufacturing the heat pipe 100 shown in FIG. The manufacturing method of the heat pipe 100 will be described in detail along the process flow of FIG.

  First, as a first step, a pipe (first metal pipe) made of a first metal containing copper is inserted into one end of a pipe made of a second metal containing aluminum (second metal pipe). Then, as shown in FIG. 4, the outer wall surface 104 a of the first metal tube 104 and the inner wall surface 105 a of the second metal tube 105 overlap each other. As the first metal, a metal containing 99.9 [%] or more of copper is used. As the second metal, a material containing aluminum in a ratio of 99 [%] or more is used. For the first metal tube 104, for example, one having an outer diameter of 6.70 [mm] and an inner diameter of 6.60 [mm] is used. For the second metal tube 105, for example, one having an outer diameter of 10.00 [mm] and an inner diameter of 6.70 [mm] is used.

  Next, as a second step, the object 108 in a state where the outer wall surface 104a of the first metal tube and the inner wall surface 105a of the second metal tube overlap each other is drawn, and the first metal tube 104 and the first metal tube 104 The two-metal tube 105 is crimped. In this drawing process, as shown in FIG. 5, the workpiece 108 is inserted in the direction D from one end 12a to the other end 12b of the through-hole provided in the die 11, and the workpiece 108 is inserted from the other end 12b side. Pull it out.

  The opening surface at one end 12a of the through hole is formed wider than at least the cross section of the object to be processed 108 in the insertion direction D. The opening surface of the other end 12b of the through hole is formed to be narrower than the cross section of the object to be processed 108 at least perpendicular to the insertion direction D. As a drawing method, it is only necessary to be able to crimp two tubes in an overlapped state. For example, there are a ball drawing method, a drawing method using a floating plug, and a mandrel drawing method.

  Next, as a third step, heat treatment (annealing) is performed on the object to be processed 108 that has been drawn. Specifically, for example, during the third step, the temperature of the support base (support means) of the target object 108 is controlled to indirectly heat the target object 108. In the third step, the heating time is desirably 30 [min] or more and 90 [min] or less, and the heating temperature range is desirably 300 [° C.] or more and 450 [° C.] or less. When the heating time is less than 30 [minutes], and when the heating temperature is less than 300 [° C.], the workpiece 108 tends not to be normally annealed. When the heating time exceeds 90 [minutes], and the heating temperature exceeds 450 [° C.], the finally formed intermetallic compound layer tends to be too thick.

  Through the first to third steps described above, the first metal tube 104 and the second metal tube 105 are pressure-bonded as shown in FIG. A metal compound layer 106 formed by metal bonding to a metal can be formed.

  FIG. 7 is an enlarged photograph of the vicinity of the interface in the sample that has actually been processed in the first to third steps, using an optical microscope. An intermetallic compound layer 106 having a thickness of about 2 [μm] is formed between the first metal layer 104 and the second metal layer 105. The thickness of the intermetallic compound layer 106 is on the order of several μm regardless of the thicknesses of the first metal layer 104 and the second metal layer 105.

  After forming the metal compound layer 106, the working fluid is injected into the first metal tube 104, and both ends of the first metal tube 104 and the second metal tube 105 are sealed, whereby the heat shown in FIG. The pipe 100 can be formed.

  Injection of a working medium such as a working fluid and sealing of both ends of the metal tube can be performed using a vacuum degassing method, a heat purge method, or the like. In the vacuum degassing method, a working medium is injected into a pipe with one end sealed using a dropper or pipette, the inside of the pipe is depressurized and heated, and the working medium in the pipe is boiled to perform deaeration. This is a method of sealing the other end. In the heating and purging method, a working medium larger than the enclosed amount is injected into a pipe with one end sealed, and the pipe is heated to boil the working medium and deaerate, and then seal the other end. Is the method. Sealing at both ends of the metal tube is performed by pressure bonding or welding. The working medium is deaerated for the purpose of reducing the pressure inside the pipe after sealing.

  For a first metal tube having an outer diameter of 6.70 [mm] and an inner diameter of 6.60 [mm] and a second metal tube having an outer diameter of 10.00 [mm] and an inner diameter of 6.70 [mm], When the process described above is performed (FIG. 4), a heat pipe having an outer diameter of about 3.00 [mm] and an inner diameter of about 1.98 [mm] can be formed (FIG. 6). In addition, the dimension of each component shown to FIG. 4, 6 is an example, and can be adjusted suitably.

  In addition to the heat pipe manufacturing method described above, the heat pipe can also be manufactured by, for example, plating a metal constituting the first metal tube in the second metal tube and performing a heat treatment.

  As a first embodiment, a case where a cylindrical heat pipe is manufactured has been described as an example, but a planar heat pipe is obtained by further pressing a heat pipe that has undergone the third step described above. Can be manufactured.

  After the third step described above, as a fourth step, various wicks such as a metal mesh laminated wick made of a metal containing copper, a metal fiber wick, and a carbon fiber may be attached in the heat pipe.

  The metal mesh laminated wick can be attached, for example, by inserting a desired wick into the heat pipe (in the first metal pipe), fixing one end of the wick, and further pushing the bearing steel ball from the fixed end side. Can be carried out by pressing against the inner wall of the first metal tube.

  The wick of the carbon fiber or metal fiber can be attached by inserting the fiber bundle into the heat pipe (in the first metal tube) and further inserting a spring to press the wick against the inner wall of the first metal tube. .

  Hereinafter, the present invention will be described more specifically using Examples 1 and 2 corresponding to the first embodiment. However, examples to which the present invention can be applied are not limited to Examples 1 and 2. Absent.

[Example 1]
When the bending process is performed on the heat pipe 100 in FIG. 1, the layer made of the second metal (the second metal) with respect to the thickness of the first metal layer (the first metal layer) and the internal space of the heat pipe. An experiment was conducted to investigate the relationship between the exposure of the layer) and the presence or absence of exposure. The bending process was performed by deforming the heat pipe so as to form a fan-shaped arc having a radius of 20 [mm] and an angle of 90 [degrees]. The total thickness of the first metal layer and the second metal layer was adjusted to 500 [μm]. Samples 1, 2, and 3 in which the thickness of the first metal layer was 5, 10, and 20 [μm] were used as experimental samples.

  Table 1 summarizes the experimental results for Samples 1, 2, and 3. Regarding the presence / absence of the exposure of the second metal layer, the bent part is observed using a scanning microscope, and the case where the exposure is not confirmed is indicated by a circle, and the case where the exposure is confirmed is indicated by an x mark. . As shown in Table 1, the thickness of the first metal layer required to prevent the second metal layer from being exposed by bending is at least larger than 5 [μm], more preferably 10 [μm] or more. I found out.

[Example 2]
An experiment was conducted to investigate the relationship between the thickness of the second metal layer and whether or not the first metal layer was exposed to the external space of the heat pipe when the heat pipe 100 of FIG. 1 was bent. . The bending process was performed by deforming the heat pipe so as to form a fan-shaped arc having a radius of 20 [mm] and an angle of 90 [degrees]. The total thickness of the first metal layer and the second metal layer was adjusted to 500 [μm]. Samples 4, 5, and 6 in which the thickness of the second metal layer was 5, 10, and 20 [μm] were used as experimental samples.

  Table 2 summarizes the experimental results for samples 4, 5, and 6. Regarding the presence / absence of the exposure of the first metal layer, the bent part is observed using a scanning microscope, and the case where the exposure is not confirmed is shown as a circle, and the case where the exposure is confirmed is shown as an x mark. . As shown in Table 2, the thickness of the second metal layer required to prevent the exposure of the first metal layer by bending is at least greater than 5 [μm], more preferably 10 [μm] or more. I found out.

  The present invention can be widely applied to devices equipped with elements that require cooling, such as semiconductor packages.

100, 110, 200 ... heat pipe, 101, 111 ... container,
101a ... first end, 101b ... second end,
102, 202 ... working medium, 103, 113, 203 ... sidewalls,
104, 114, 204 ... inner layer, 104a ... outer wall surface,
105, 115, 205 ... outer layer, 105a ... inner wall surface,
106, 116 ... Metal compound layer, 117 ... Wick, 108 ... Object to be treated, 11 ... Dice, 12a ... One end, 12b ... Other end, D, L, S. ··direction.

Claims (3)

A container consisting of a sealed pipe and having a first end and a second end;
A working medium held in the container,
The working medium evaporated at the first end is condensed at the second end, and heat transfer is performed from the first end to the second end.
Of the side walls of the container, the inner layer is constituted by a first metal containing copper, and the outer layer is constituted by a second metal containing aluminum,
A heat pipe comprising a layer made of an intermetallic compound between the inner layer and the outer layer.   The heat pipe according to claim 1, wherein the layer formed of the intermetallic compound contains aluminum and copper.   The heat pipe according to claim 1 or 2, further comprising a wick made of a third metal containing copper inside the side wall.