JPH10253274A - Sheet-type heat pipe and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an efficient sheet-type heat pipe where the move of a heat due to an operation fluid has a directivity by providing a wire or a wire mesh at least at one portion of a plurality of through holes that communicate one another at both edge parts in the sheet-type heat pipe for releasing heat being generated by an electronic part. SOLUTION: Approximately ten through holes 11 are provided in a row at a container 10 of a sheet-type heat pipe 1, the through holes 11 are connected at both edge parts of the sheet-type heat pipe 1, and at the same time a wire 12 or a wire mesh is provided in the through hole 11. The wire 12 can maintain a certain degree of reflux operation of the operation fluid even in the case of a top mode where a heat-absorption part is located at the upper part from the cooling part due to capillary force cause by a narrow gap being formed at an area to the inner wall of the through holes 11, thus maintaining a certain degree of heat transfer performance even in the top heat mode. The wire 12 preferably occupies 5-40 % of the sectional area of the through holes 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sheet-type heat pipe and a method for manufacturing the same.

[0002]

2. Description of the Related Art Electronic components such as semiconductor elements mounted on various devices such as personal computers and electric and electronic devices such as electric power equipment are inevitable to generate a certain amount of heat by their use. It is becoming a technical issue. As a method of cooling an electric component requiring cooling (hereinafter, referred to as a cooled component), for example, a method of attaching a fan to the device to lower the temperature of air in the device housing, or a method of attaching a cooling body to the component to be cooled, A method of particularly cooling the cooled component is typically known.

As a cooling body attached to a component to be cooled, a plate made of a material having excellent heat conductivity, such as a copper material or an aluminum material, is used. It is more effective to attach a radiating fin to such a plate material or to use a plate material and a fin integrally formed (by casting, forging, or the like). This type of cooling body is sometimes called a heat sink or the like.

In recent years, as a cooling body to be attached to a component to be cooled, a heat pipe is attached to a cooling body having a heat pipe structure or a plate having excellent heat conductivity, such as a copper material or an aluminum material, instead of a mere heat conductive metal material. Is proposed and put to practical use. When a cooling body having a heat pipe structure is used, a flat heat pipe is often preferred because it is attached to a component to be cooled.

[0005] As its name implies, a heat pipe is typically a round pipe, but a flat (flat) heat pipe is also known as a heat pipe. In any case,
A space serving as a flow path for the working fluid is provided therein, and the working fluid contained in the space undergoes a phase change such as evaporation and condensation or moves, so that heat is transferred. The working fluid is sometimes referred to as a working fluid, but is also in a vapor state, and is hereinafter referred to as a working fluid.

[0006] The heat pipe has a sealed cavity, and heat is transferred by phase transformation and movement of the working fluid contained in the cavity. Of course, some heat is transferred by conducting heat through a container (container) constituting the heat pipe. However, the heat pipe is a heat transfer device mainly intended to perform a heat transfer operation by a working fluid.

[0007] The working fluid in the heat pipe is usually
Water, an aqueous solution, alcohol, and other organic solvents are used. As a special application, mercury may be used as a working fluid. As described above, since the heat pipe utilizes the action such as phase transformation of the working fluid inside, the heat pipe is manufactured so as to minimize mixing of gases and the like other than the working fluid into the sealed interior. . Such contaminants are usually air (air) mixed during the production or carbon dioxide dissolved in the working fluid.

What is usually called a heat pipe is as follows:
Many have a round pipe shape. However, in recent years, application of a planar heat pipe as a cooling device suitable particularly for cooling electronic components related to power electronics has been regarded as promising. The planar heat pipe is not necessarily a flat plate, but may have a curved plane as appropriate. In this specification, such a heat pipe is referred to as a sheet-type heat pipe.

Since the sheet-type heat pipe has a flat plate shape, it has an advantage that it can be easily thermally connected to the cooled component in an application for cooling an electronic component (cooled component) such as an IC element. Also, when the radiation fins are attached to the sheet-type heat pipe, there is an advantage that the connection can be made in a wide area. For this reason, sheet-type heat pipes are promising in recent years.

The operation of the heat pipe is briefly described as follows. That is, on the heat absorbing side of the heat pipe, the working fluid evaporates due to heat transmitted through the material of the container (container) constituting the heat pipe, and the vapor moves to the heat radiation side of the heat pipe. On the heat radiation side, the vapor of the working fluid is cooled and returns to the liquid state again. Then, the working fluid that has returned to the liquid phase moves (recirculates) to the heat absorbing side again. Heat is transferred by such phase transformation and movement of the working fluid.

In the case of a gravity-type heat pipe, the working fluid that has been brought into a liquid phase by phase transformation moves (refluxes) to the heat-absorbing side by gravity or capillary action. In this case, the heat absorption side may be disposed below the heat radiation side.

[0012]

It is known that a sheet-type heat pipe has an advantage that its shape makes it easy to come into contact with a component to be cooled such as an electronic component over a large area. Therefore, as such a sheet-type heat pipe, two flat plates joined by welding or the like so that a cavity is formed between them, or two flat plates partially coated with a release agent are swelled. A device having a hollow portion formed has been proposed.

However, the above-mentioned sheet type heat pipe is
Although it has a planar cavity inside it, in such a form, the moving direction of the working fluid is multidirectional, and it can be said that the heat transfer from the heat absorbing portion to the heat radiating portion is not necessarily efficient. Absent.

When a heat pipe is applied to a cooling mechanism of an electronic component, the heat pipe is arranged so that the heat absorbing side is located below the heat radiating side (this type of operation of the heat pipe is called a bottom heat mode). By doing so, it is possible to expect the working fluid to return by gravity. Therefore, when cooling the electronic components in the apparatus which is installed in a state where it does not substantially move, the heat absorbing side may always be arranged below the heat radiating side. However, such convenience in arrangement means that the degree of freedom of design is limited as much as a cooling mechanism using a sheet-type heat pipe.

In the case of a mobile device, a portable electric device, or an electric control device attached to an overhead electric wire, it is expected that the vertical positional relationship between the heat-absorbing side and the heat-dissipating side may fluctuate during use (operation). You. When the heat absorbing side is located above the heat radiating side (such an operation form of the heat pipe is called a top heat mode), the working fluid cannot be recirculated by gravity, so that the working fluid is insufficient in the heat absorbing portion. May be in the state of empty firing.

Even in the top heat mode, if the height difference between the heat radiating side and the heat absorbing side or the distance between them is small, the above-described problem of the empty heating is less likely to occur. However, since the heat pipe is originally used for transporting heat, the distance between the heat radiation side and the heat absorption side is often required to some extent. In addition, the restriction that the height difference between the heat radiation side and the heat absorption side or the distance between them is reduced imposes a corresponding restriction on the use (operation) of various devices provided with the cooling mechanism.

Under such circumstances, it has been desired to develop an efficient sheet-type heat pipe that achieves excellent performance even in the state of the top heat mode and has a direction in the transfer of heat by the working fluid.

[0018]

The invention proposed in the present invention has a plurality of through-holes communicating at both ends, and at least a part of the through-holes is provided with a wire or a wire mesh. It is a pipe. Preferably, the wire or wire mesh extends to both ends of each hole. When the wire or wire mesh is made of a wire having a substantially polygonal cross section, or when the wire or wire mesh is made of a wire having a groove formed on the surface, the wire or the wire mesh is further twisted. It may be constituted by a wire of the form. Further, such a wire or a wire mesh may be spirally inserted into the hole. The wire or wire mesh may occupy 5 to 40% of the cross-sectional area of the through hole provided.

As a method for manufacturing the sheet-type heat pipe of the present invention, a multi-hole pipe is prepared, and near the end of the multi-hole pipe, a partition separating each hole is partially removed to close the end. It is preferable to use a method of forming a sheet-type heat pipe container with the above method. Further, a method of forming a container of a sheet-type heat pipe connected to the multi-hole pipe by joining a cap member to an end of the multi-hole pipe may be used.

[0020]

FIG. 1 is a cross-sectional view of a sheet-type heat pipe according to the present invention. The container 10 is provided with ten through-holes 11 in a row, and these through-holes 11 communicate with both ends of the sheet-type heat pipe 1, and a wire 12 is provided in the through-hole 11. I have. Note that a wire mesh may be provided in the through hole 11 instead of the wire 12.

Although not shown in the drawing, a predetermined amount of working fluid is stored in the through hole 11 or in a portion communicating with both ends. When this sheet-type heat pipe 1 is used, it is preferable to arrange the heat absorbing portion and the heat radiating portion so that the heat transfer by the working fluid is performed along the length direction of the through hole.
By doing so, a more efficient cooling mechanism is realized.

In the sheet type heat pipe 1 shown in FIG.
Although an example in which ten through holes 11 are provided is given, the number is arbitrary. In this example, the wire 12 is provided in all of the through holes 11, but the wire 12 is
1 may be provided at least in part.

The wire 12 forms a narrow gap with the inner wall of the through hole 11 so as to generate a strong capillary force.
Due to the capillary force generated by the gap, a certain degree of recirculation of the working fluid can be maintained even in the case of the top heat mode in which the heat absorbing section is located above the heat radiating section. Therefore, a certain degree of heat transfer performance can be maintained even in the top heat mode.

The wire 12 has a sectional area of 5 to 5
It is good to occupy 40%. Not much wire 12
When the cross-sectional area occupied by the hydraulic fluid becomes large, the passage of the working fluid which has turned into a vapor becomes narrow, and the movement resistance thereof is undesirably increased. In addition, the wire 1 is inserted into at least a part of the through hole 11.
As described above, it is only necessary to provide the through holes 2. However, if the wires 12 are provided in all the through holes 11, the total volume of the passage of the working fluid that has turned into a vapor decreases. Therefore, the number of through holes 11 in which the wires 12 are provided may be appropriately selected according to the required performance and the like.

In these sheet-type heat pipes, a sheet-type heat pipe is prepared by preparing a multi-hole pipe, partially removing a partition separating each hole near the end of the multi-hole pipe, and closing the end. Forming a pipe container is desirable in terms of manufacturing costs and other aspects. Further, a container of a sheet-type heat pipe may be formed by joining a cap member to an end of the multi-hole tube.

[0026]

【Example】

Example 1 Sheet type heat pipe 1 having a cross section as shown in FIG.
Was prepared. This sheet-type heat pipe 1 is manufactured by a multi-hole extrusion process to produce a multi-hole pipe having 10 through holes each having a thickness of 2 mm, a width of 60 mm, and a cross-sectional size of 4.45 mm × 1 mm. It was manufactured by attaching cap members to both end portions of each to allow all the through holes 11 to communicate with each other. A pure Al-based material was used for the multi-hole tube and the cap member.

The inside of the cavity formed by the multi-hole tube and the cap member is evacuated by vacuum, and HCFC is used as a working fluid.
Was accommodated. The wires 12 (made of pure Al) having a diameter of 0.8 mm and a length of 300 mm are inserted into the through holes 11 one by one. The overall length of the sheet heat pipe 1 thus manufactured was about 500 mm.

FIG. 2 is a diagram for explaining the performance evaluation of the sheet type heat pipe 1. As shown in FIG. FIG. 2A is a plan view showing a state in which parts to be cooled 30 and 31 (size: 30 mm × 30 mm) are mounted near one end of the sheet-type heat pipe 1 and radiation fins 2 are mounted near the other end. is there. Although not shown, the wire 12 is disposed so as to be located substantially at the center with respect to the length direction (left-right direction in the drawing) of the sheet-type heat pipe 1. FIG. 2A is a side view, and the inclination angle α indicates the rising angle (°) of the sheet-type heat pipe 1 from the horizontal.

The components to be cooled 30, 31 (both 2 W in heat generation) were operated to generate heat. And the tilt angle α
, The difference between the average of the temperature of the portion of the sheet-type heat pipe 1 to which the parts to be cooled 30 and 31 were attached and the average of the temperature of the portion to which the radiation fins 2 were attached was examined. . Table 1 shows the results. Note that α
In FIG. 2 (a), the notation "+" is used when the sheet-type heat pipe 1 is inclined leftward and the notation "-" is used when the sheet heat pipe 1 is inclined rightward.

For comparison, a sheet-type heat pipe having one hollow portion without a partition wall 110 separating the through holes 11 of FIG. 1 was prepared. The hollow portion is provided with 225 6 mm columns at substantially equal intervals from the viewpoint of improving the pressure resistance. No wire or wire mesh was provided in the sheet heat pipe of this comparative example. In addition, the working fluid and the like are the same as those of the sheet-type heat pipe 1 of the present invention. The characteristic evaluation as shown in FIG. 2 was also performed on the sheet heat pipe of this comparative example. In the comparative example,
When the inclination angle α was −10 or more, the sheet-type heat pipe 1 was in an empty firing state. The results are also shown in Table 1.

[0031]

[Table 1]

As can be seen from Table 1, the sheet-type heat pipe 1 of the present invention has the following characteristics when the inclination angle α is negative.
That is, even in the case of the top heat mode in which the parts 30 and 31 to be cooled are located above the radiating fins 2, an excellent heat transfer performance with a small temperature difference has been realized. On the other hand, in the sheet heat pipe of the comparative example, the heat transfer performance was significantly reduced in the top heat mode.

Example 2 Sheet type heat pipe 4 having a cross section as shown in FIG.
Was prepared. As a method for manufacturing the sheet-type heat pipe 4, a thickness of 1.9 mm, a width of 50 mm, and a size of the through holes 41 (20 pieces) is 2.0 mm by a multi-hole extrusion process.
A method of manufacturing a multi-hole tube of × 0.9 mm and attaching cap members to both ends of the multi-hole tube to allow all the through holes 41 to communicate with each other was adopted. A pure Al-based material was used for the multi-hole tube and the cap member.

The inside of the cavity formed by the multi-hole tube and the cap member is evacuated to vacuum, and HCFC is used as a working fluid.
Was accommodated. In the through hole 41, a wire (material: pure Al) having a diameter of 0.5 mm and a length of 410 mm is inserted one by one. The total length of the sheet heat pipe 4 thus manufactured was about 450 mm.

FIG. 4 is a diagram for explaining the performance evaluation of the sheet type heat pipe 4. As shown in FIG. FIG. 4A shows an electric power in which the vicinity of one end of the sheet-type heat pipe 4 is brought close to the parts to be cooled 60 to 63 (size: 20 mm × 30 mm), and the vicinity of the other end is the space where the parts to be cooled 60 to 63 are housed. It is a top view explaining the state where it was thermally connected to case 5 of the device. In the vicinity of one end of the sheet-type heat pipe 4, the parts to be cooled 60 to 6 are provided.
Heat is transmitted by the radiant heat from 3 and heat transfer through the surrounding air.

FIG. 4A is a side view, but the sheet-type heat pipe 4 is bent near the middle as shown. The inclination angle α (°) indicates the inclination of the sheet heat pipe 4 from the horizontal.

Now, the components to be cooled 60 to 63 (both having a heating value of 2.5 W) are operated to generate heat, and the components to be cooled of the sheet-type heat pipe 4 after the lapse of a predetermined time at α shown in Table 2. The average of the temperature of the portion adjacent to 60 to 63;
The difference from the average of the temperature of the part attached to the housing 5 of the electric device was examined. Table 2 shows the results.

For comparison, a sheet-type heat pipe having no wire mesh 42 shown in FIG. 3 was prepared.
For this, the same performance evaluation as that of the example of the present invention was performed. The results are also shown in Table 2. As in the case of the first embodiment, α is represented by + notation when the sheet-type heat pipe 4 is inclined leftward in FIG. 4A, and is indicated by-notation when the sheet heat pipe 4 is inclined rightward. . In the comparative example, the inclination angle α
When the angle was −10 or more, the sheet-type heat pipe 1 was in an empty firing state.

[0039]

[Table 2]

As can be seen from Table 2, the sheet-type heat pipe 4 of the present invention has the following characteristics when the inclination angle α is minus.
That is, even in the case of the top heat mode in which the portion close to the components to be cooled 60 to 63 is located above the portion where the electrical device is attached to the housing 5, excellent heat transfer performance with a small temperature difference has been realized. On the other hand, in the sheet heat pipe of the comparative example, the heat transfer performance was significantly reduced in the top heat mode.

[0041]

As described above in detail, the sheet-type heat pipe and the method for manufacturing the same according to the present invention realize excellent heat transfer performance with a small temperature difference even in the top heat mode. Therefore, the use of the sheet-type heat pipe of the present invention realizes an excellent cooling mechanism that can cope with various forms.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of a sheet-type heat pipe according to the present invention.

FIG. 2 is an explanatory diagram showing a method for measuring the heat transfer performance of a sheet-type heat pipe in an example.

FIG. 3 is a cross-sectional view of another example of the sheet heat pipe according to the present invention.

FIG. 4 is an explanatory diagram showing a method for measuring the heat transfer performance of a sheet-type heat pipe in an example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet type heat pipe 10 container 11 through hole 12 wire 110 partition 2 radiating fin 30 cooled part 31 cooled part 4 sheet type heat pipe 40 container 41 through hole 42 wire 5 electrical equipment housing 60 cooled part 61 cooled Component 62 Component to be cooled 63 Component to be cooled

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jun Sakagawa 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Hisao Enomoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Within Furukawa Electric Co., Ltd. (72) Inventor Yasushi Kojima 4-1-1 Umedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Within Fujitsu Co., Ltd. (72) Inventor Yama ▲ Saki ▼ Naoya 4 Ueodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa 1-1 Inside Fujitsu Limited (72) Inventor Masahiro Mogi 2-3-9 Shin-Yokohama, Kohoku-ku, Yokohama, Kanagawa Prefecture Within Fujitsu Digital Technology Limited

Claims (8)

[Claims] A plurality of through holes communicating at both ends;
A sheet-type heat pipe, wherein at least a part of the through hole is provided with a wire or a wire mesh. 2. A wire according to claim 1, wherein said wire or wire mesh is made of a wire having a substantially polygonal cross section.
The sheet heat pipe as described. 3. The sheet-type heat pipe according to claim 1, wherein the wire or the wire mesh is formed of a wire having a groove formed on a surface thereof. 4. The wire or wire mesh according to claim 1, wherein the wire or wire mesh is formed of a stranded wire.
4. The sheet-type heat pipe according to any one of items 1 to 3. 5. The sheet-type heat pipe according to claim 1, wherein said wire or wire mesh is spirally inserted into said hole. 6. The sheet type heat pipe according to claim 1, wherein the wire or the wire mesh occupies 5 to 40% of a cross-sectional area of a through hole provided therein. 7. A sheet-type heat pipe container is formed by partially removing a partition wall separating each hole in the vicinity of an end of the multi-hole tube and closing the end. 3. The method for producing a sheet-type heat pipe according to item 1. 8. A sheet-type heat pipe according to claim 1, wherein a cap member is joined to an end of the multi-hole pipe to connect the multi-hole pipe to form a container for a sheet-type heat pipe. Pipe manufacturing method.