KR20040019150A - flat type heat pipe and heat sink - Google Patents

Abstract

PURPOSE: A flat type heat pipe and a heatsink are provided to increase a heat radiation effect and reduce a heat resistance by installing a wick having parallel channels in the inside of the flat type heat pipe. CONSTITUTION: A flat type heat pipe includes a flat pipe(15) and a wick(17). The working fluid is injected into the flat pipe(15). The flat pipe(15) is sealed after the working fluid is injected into the flat pipe(15). The wick(17) is formed in the inside of the flat pipe in order to vaporize the working fluid, transport the vapor, condense the vapor to the longitudinal direction of the flat pipe. A plurality of channels(19) are formed in the wick(17) in order to guide the movement of vapor. The channels(19) are arranged in parallel to the lateral direction of the flat pipe(15).

Description

Flat type heat pipe and heat sink

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat heat pipe provided with a wick having a plurality of channels, which are vapor passages, and a heat sink having the flat heat pipe.

As known in the art, the heat pipe seals a working fluid inside a sealed container, and has excellent characteristics such as a simple structure, a large amount of heat transportation, and no need for external power. Therefore, conventional heat pipes are used for heat transfer, heating, cooling, and the like. In particular, electronic components of computers, such as semiconductors, have tended to become more integrated, higher capacity, and higher speed in recent years. In accordance with this tendency, the density of heat generated in the device is also increasing, so the use of heat pipes for effectively cooling these heats is being expanded.

In addition, the trend toward miniaturization of computers is focusing on the thickness of heat sinks, particularly the bases, on which these heat pipes are installed. That is, minimizing the thickness of the base has a linkage with the heat pipe, and it is preferable to be embedded in the base while maintaining the same amount of heat transportation in terms of structural and assembly properties.

Thus, as shown in Figs. 6 to 8 as a conventional heat pipe in which a heat pipe is embedded in the base. As is well known, the heat pipe 230 shown in FIGS. 7 and 8 includes a circular pipe 231 in which a phase change working fluid is vacuum-injected and a wick wick formed on the inner surface of the pipe 231. It consists of. The wick 232 is configured such that the working fluid is evaporated (E), the movement of the vapor (VF), condensation (C) and the reflux (R) of the working fluid as shown in FIG. In addition, the circular heat pipe 230 embedded in the heat sink 200 has heat transportation (steam movement) not only in the longitudinal direction (length direction) but also in the transverse direction (cross section direction) shown in FIG. Is done. That is, the channel 239 which is a moving passage of the steam is formed in a single unit, and the evaporation unit 233, the condensation unit 235, and the reflux unit 237 are formed around the channel 239. The heat pipe 230 is inserted into the heat dissipation fin 9 and the hole 210 formed on one side of the base 230 in a plurality of upper surface 270 of the base 230, thereby forming a heat sink 200. . In addition, an electronic device is attached to the lower surface 250 of the heat sink 200. This electronic element becomes the heating source Q, and the part to which the electronic element is attached becomes an evaporation part.

However, since the heat pipe 230 tends to have a thick thickness of the base 220 as a circular shape, the heat pipe 230 having a minimum diameter is embedded in the base 220 at predetermined intervals as shown in FIG. 6. have. However, minimizing the diameter reduces the heat transfer limit (pump amount) due to the liquid pressure drop due to the reduction of the capillary flow passage and the increase of the steam pressure drop during the steam flow, and when heat is conducted from the heat source to the evaporation portion of the heat pipe. As the effective evaporation area is reduced, problems such as an increase in the heat flux and an increase in the thermal resistance occur, which may cause a decrease in heat transfer efficiency (cooling efficiency).

In particular, when the heat sink fin is installed at the lower part of the base (usually called Top heating mode), the heat should be transferred in the direction of gravity by capillary force without the help of the gravitational field (the working fluid is in the opposite direction of gravity). The reduction of the capillary passages due to the limitation of the diameter limits the installation of the capillary structures, thereby limiting the increase in heat transfer limits.

In addition, as the heat pipes 230 are each embedded in the base 220, there is a problem such as an increase in the number of assembly operations and an increase in assembly costs.

In addition, there is a hassle to seal the heat pipe 230 by vacuum injection of the working fluid.

To solve this problem, as shown in Figs. 9 and 10, a heat sink in which a heat pipe is inserted into a base with a flat plate type is proposed in Japanese Laid-Open Patent Publication No. 2002-64170. The heat sink 100 includes a base 120, a plurality of heat dissipation fins 9 installed on the top surface 170 of the base 120, a recess 110 formed on the bottom surface 150 of the base 120, and the recess portion ( It is composed of a flat heat pipe 130 is fitted into the coupling 110, it is possible to reduce the assembly labor while minimizing the thickness of the base.

However, the flat heat pipe 130 having the single channel 139 also has a similar problem in that it has the same heat transport structure as the circular heat pipe 230 described above. That is, since the heat conduction from the lower wall to the upper wall of the plate heat pipe to which heat is applied is made only through the side walls, the heat resistance increases due to the reduction of the evaporation heat transfer area and the flow of all the working fluids refluxed from the longitudinal direction is lateral. The capillary limit due to the reduction of the flow area of the working fluid can be lowered because it must be made only by the capillary forces of the over and under wick.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object thereof is to provide a flat heat pipe that can increase the heat transfer limit (pumping amount) and reduce the thermal resistance.

Another object of the present invention is to provide a heat sink having a flat heat pipe capable of transferring a large amount of heat while minimizing the thickness of the base.

It is still another object of the present invention to provide a flat heat pipe assembly and a heat sink having a structure in which a working fluid can be vacuum-injected into each heat pipe in one circuit and an excess working fluid can be utilized where necessary.

1 is a perspective view of a heat sink according to a preferred embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the flat heat pipe of FIG. 1. FIG.

3 is a perspective view of a heat sink according to another preferred embodiment of the present invention.

4 is a perspective view illustrating a heat pipe assembly in which the flat heat pipe of FIG. 1 is installed in parallel.

FIG. 5 is a perspective view of another heat sink in which the flat heat pipe assembly of FIG. 4 is installed. FIG.

6 is a perspective view of a conventional heat sink.

7 is an enlarged longitudinal sectional view of the heat pipe of FIG. 6;

8 is an enlarged cross-sectional view of the heat pipe of FIG. 6.

9 is a perspective view of another conventional heat sink.

10 is an enlarged cross-sectional view of the heat pipe of FIG. 9.

<Explanation of symbols for the main parts of the drawings>

1,1a, 1b: Heat sink 2,2a, 2b: Base

5: Base lower surface 7: Base upper surface

9: heat sink fin 11: opening

11a: recess 11b: recess

11c: seating portion 13: flat heat pipe

13a: flat heat pipe assembly 14: reservoir

15,131.231: Flat pipe 17,132,232: Wick

19,139,239 Channel 21,133,233 Evaporator

23,135,235 Condensation unit 25,25a, 137,237 Reflux unit

E: evaporation zone VF: vapor movement zone

C: condensation zone R: reflux line

According to an aspect of the present invention, there is provided a flat plate heat pipe comprising: a flat pipe in which a phase change working fluid is injected and sealed; It includes a wick sintered in the interior of the flat pipe so that the working fluid is evaporated, the movement of steam, condensation, reflux along the longitudinal direction of the flat pipe,

The wick is provided with a plurality of channels for guiding the movement of the steam,

Each of the channels is arranged in parallel along the transverse direction of the flat pipe.

Through this configuration, it is possible to increase the heat transfer limit and decrease the thermal resistance by increasing the capillary flow passage and decreasing the steam pressure drop in the steam flow.

Heat sink having a flat plate heat pipe according to another aspect of the present invention; A plurality of heat dissipation fins installed on an upper surface of the base; It includes a flat heat pipe installed in the base,

The flat heat pipe includes a flat pipe and a wick in which a plurality of channels, which are vapor passages, are sintered and molded into the flat pipe, and condensation is formed between the upper wall of the flat pipe and the channel around each channel of the wick. And an evaporation unit formed between the lower wall of the plate pipe and the channel, and a working fluid formed between the sidewall and the channel of the plate pipe and between the channel and the channel and condensed in the condensation unit is returned to the evaporator. It consists of the reflux part which becomes.

Through this configuration, a large amount of heat can be transported while minimizing the thickness of the base.

In the above-described configuration, it is preferable that a plurality of openings into which the flat heat pipe is inserted are formed at the side of the base, or a plurality of recesses into which the flat heat pipe is inserted are formed at the bottom of the base.

According to another aspect of the present invention, a flat plate heat pipe assembly includes: a flat pipe in which a phase change working fluid is injected and sealed; It consists of a wick sintered and molded in the inside of the flat pipe so that the working fluid evaporates, moves, condenses, and reflux along the longitudinal direction of the flat pipe, and the wick is formed with a plurality of channels for guiding the movement of the steam. Each of the channels is provided with a plurality of heat pipes arranged in parallel along the transverse direction of the flat pipe,

A reservoir communicating with the channel of each of the heat pipes is provided at one end of the heat pipes arranged in parallel.

Through this configuration, the working fluid can be vacuum-injected into each heat pipe in one circuit, and the excess working fluid can be utilized where necessary.

According to another aspect of the present invention, a heat sink includes: a flat pipe in which a phase change working fluid is injected and sealed; It consists of a wick sintered and molded in the inside of the flat pipe so that the working fluid evaporates, moves, condenses, and reflux along the longitudinal direction of the flat pipe, and the wick is formed with a plurality of channels for guiding the movement of the steam. Each of the channels is provided with a plurality of heat pipes arranged in parallel along the transverse direction of the flat pipe, and a reservoir communicating with the channels of each of the heat pipes is provided at one end of the heat pipes arranged in parallel. An assembly of a flat plate heat pipe, a base, a plurality of heat dissipation fins provided on an upper surface of the base, a plurality of concave portions formed on a lower surface of the base such that the flat plate heat pipe is installed, and having one side open; It comprises a seating portion formed on the lower surface of the base to be seated.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described.

Example 1

1 is a perspective view of a heat sink according to a preferred embodiment of the present invention, Figure 2 is an enlarged cross-sectional view of the heat pipe of FIG. As shown in FIG. 2, each of the heat pipes 13 according to the present embodiment is largely composed of a wick 17 having a flat pipe 15 and a plurality of channels 19.

The wick 17 is sintered and formed in the flat pipe 15, and a condensation part 23 formed between the channel 19 and the upper wall of the flat pipe 15 around each channel 19 of the wick 17. ), Between the bottom wall of the flat pipe 15 and the channel 19, between the side wall and the channel 19 of the flat pipe 15 and between the channel 19 and the channel 19. It is comprised by the formed reflux part 25 (25a). The reflux portion 25a secured by the formation of the plurality of channels 19 increases the flow cross-sectional area of the working fluid to transfer a large amount of heat in the narrow passage, thereby increasing the capillary flow passage to reduce the liquid pressure drop, thereby transferring heat. It can increase the limit. In addition, by forming the wick 17 into the porous material of the metal sintered body, a considerable thermal conductivity is increased by increasing the heat conduction cross-sectional area through the metal wick, thereby reducing the thermal resistance, and the movement of vapor and liquid is easy, so that the local large Even when a heat load is given, the cooling effect can be increased by freely moving not only in the longitudinal direction but also in the transverse direction of the channel 19.

The heat sink to which the heat pipe of this embodiment is applied will be described below. The heat sink 1 of the present embodiment includes a base 2, a plurality of heat dissipation fins 9 installed perpendicular to the upper surface 7 of the base 2, and a plurality of heat pipes 13 inserted into one side of the base 2. It is composed of

In the above-described configuration, as shown in Fig. 1, the base 2 has a rectangular plate shape having a constant thickness composed of a metal having excellent thermal conductivity such as aluminum. Moreover, the opening part 11 is provided in the side surface of this base 2 at predetermined intervals. The opening 11 has a rectangular cross section, preferably rectangular. The opening 11 is provided with a flat plate heat pipe 13.

As described above, the flat plate heat pipe 13 is sealed with a working fluid such as water or alcohol, which causes a change in state, in the flat pipe 15. The flat pipe 5 has a cross section substantially the same as that of the opening 11. In addition, the flat pipe 15 is fixed to the opening 11 by means of welding such as an adhesive such as epoxy, soldering or the like, and is tightly coupled to the base 2. In addition, an electronic element is attached to the lower surface 5 of the flat pipe 15.

In addition, the heat radiation fins 9 are vertically provided on the upper surface 7 of the base 2. A plurality of heat dissipation fins 9 are provided in a thin plate, and are integrally formed with the base 2 by die casting, extrusion, cold forging, or the like. The heat radiating fins 9 are arranged in parallel at equal intervals. Also, like the base 2, the heat dissipation fin 9 is preferably made of a metal such as aluminum having excellent thermal conductivity.

On the other hand, as shown in Fig. 3, another example in which the heat pipe 13 is provided in the base 2a is shown. In this example, the heat sink 1a is almost similar to the structure of the heat sink 1 described above, except that a plurality of recesses 11a are formed on the lower surface 5 of the base 2a. After the heat pipe 13 is in close contact with the recess 11a, the heat pipe 13 is bonded to the base by lead or a heat transfer bond. Therefore, an electronic device (not shown) is directly stuck to the surface of the flat plate heat pipe 13, so that the heat of the electronic device is directly transferred to the flat plate heat pipe 13, which heats the base of the heat sink. By dispersing, the temperature of the heat generating element, that is, the thermal resistance can be lowered.

The operation of the heat sink configured as described above is as follows.

When the energized electronic device is operated, heat is generated. By this generated heat, the working fluid in the flat heat pipe 13 is heated and evaporated in the evaporator 21, the vapor flows through the channel 19, and the base 2 along the longitudinal direction of the heat pipe. The heat dissipation) is repeated to condense in the condensation part 23 and reflux to the evaporation part 21 through the reflux parts 25 and 25a. Heat transmitted to the base 2 is dissipated to the atmosphere through the heat radiation fins 8.

As described above, since the wick having a plurality of channels is sintered and formed, the increase in the heat transfer limit and the decrease in the heat resistance can be achieved, so that the height of the flat plate of the pipe having the same heat transfer can be reduced. ) Can also minimize the thickness.

Example 2

4 and 5, the reservoir 14 has a structure in which the reservoir 14 is disposed at one end so as to communicate with each other by arranging the flat heat pipes having the plurality of channels according to the first embodiment described above in parallel. A flat heat pipe assembly 13a and a heat sink 1b employing the same are shown.

That is, as shown in FIG. 4, each of the flat plate heat pipes 13 is arranged in parallel and communicates with the channels 19 of the heat pipes 13 at one end (usually a condensation portion) arranged in parallel. The reservoir 14 is installed to form one heat pipe assembly. A working fluid inlet 14a is initially provided on one side of the reservoir 14.

Thus, through the configuration of the heat pipe assembly (13a) of the second embodiment, it is easy to manufacture by one vacuum, operating fluid injection. In addition, the reservoir 14 accumulates a surplus of working fluid unnecessary for operation, and participates in heat transfer when a large amount of working fluid is required according to operating conditions. In addition, when a large amount of heat is to be transferred to some of the channels 19, the working fluid of the reservoir 14 moves to this part, and in the event that non-condensable gas is generated during operation, it collects in this part to close the operating area. The reducing factor can be prevented.

5 shows that the heat pipe assembly 13a is mounted on the heat sink 1b.

The heat sink 1b is similar in structure and function to the heat sink 1; 1a described above, but has a recess 11b and a reservoir 14 in which the heat pipe assembly 13a is fitted to the bottom surface of the base 2b. There is a difference in that the seating portion 11c on which is seated is formed. The recessed part 11b is a structure in which one side surface is opened in the above-mentioned recessed part 11a.

In this way, the heat pipe assembly 13a fitted to the base 2b is surely joined by lead or heat transfer bond.

The plate-type heat pipe and the heat sink having the heat pipe according to the present invention can be variously modified within the scope of the technical idea of the present invention without being limited to the above-described embodiments. For example, an example of a rectangular flat plate heat pipe has been presented, and an elliptical flat plate heat pipe may be applied. The heat dissipation fin may be a plate having a heat dissipation function instead of a thin plate. In addition, the heat dissipation fins may be integrally formed by the base and the manufacturing method of extrusion, die casting, cold forging, or the like, or may be manufactured separately and bonded to each other by bonding or assembly.

As described above, the flat heat pipe and the heat sink having the heat pipe according to the embodiment of the present invention have the following effects.

First, when the wicks arranged in parallel with the channels of the vapor passages are installed inside the flat pipe, ① the heat transfer (capillary) limit is increased due to the decrease in the liquid pressure drop caused by the expansion of the capillary flow passages, and the heat radiation portion is directed downward. It has excellent heat dissipation effect, ② heat of evaporation part of wick can reduce thermal resistance by considerable heat conductivity and evaporation area increase by heat conduction through sintered metal between channels, ③ use of sinter wick of porous material When the large heat load is applied due to the easy movement of steam and liquid, the cooling effect can be increased by moving freely not only in the longitudinal direction of the wick but also in the transverse direction of the channel. Even when located at, the wick structure between the channels allows the capillary flow path to be wider, increasing the heat transfer limit.

Second, the thickness of the heat pipe (the height between the upper and lower surfaces) can be reduced for the same heat transfer performance by increasing the heat transfer limit and decreasing the heat resistance of the heat pipe with the wick having a plurality of channels, thereby reducing the thickness of the base. As a result, it can be applied to the cooling of microminiature electronic elements.

Third, a plurality of openings are extruded to the side surface of the base, whereby the production is simple.

Fourth, by processing a plurality of grooves on the lower surface of the base, the surface of the electronic element and the heat pipe is in direct contact with each other to improve the heat transfer effect through a reduction in thermal resistance.

Fifth, through a flat plate heat pipe having a plurality of channels installed in parallel by a reservoir and a heat sink adopting the same, it is easy to manufacture by one vacuum and injection of a working fluid, and the reservoir 14 is unnecessary for operation. If fluid is accumulated and a large amount of working fluid is required according to the operating conditions, it participates in heat transfer. ③ If a large amount of heat must be transferred to some of the channels, the working fluid of the reservoir moves to this part. If heavy non-condensable gas is generated, it is possible to prevent the factors that gather in this area and reduce the operating area.

Claims (6)

A flat pipe in which a phase change working fluid is injected sealed; Including the wick sintered in the interior of the flat pipe so that the working fluid is evaporated, the movement of steam, condensation, reflux along the longitudinal direction of the flat pipe, The wick is provided with a plurality of channels for guiding the movement of the steam, And each of the channels is arranged in parallel along the transverse direction of the flat pipe. Base; A plurality of heat dissipation fins installed on an upper surface of the base; Is made of a flat heat pipe including the base, The flat heat pipe may include a flat pipe in which a phase change working fluid is injected and sealed; And a wick sintered and molded into the inside of the flat pipe such that the working fluid is evaporated, vapor moves, condenses, and reflux along the longitudinal direction of the flat pipe. The wick is provided with a plurality of channels for guiding the movement of the steam, And each of the channels is arranged in parallel along the transverse direction of the flat pipe. The heat sink having flat plate heat pipes according to claim 2, wherein a plurality of openings into which the plate heat pipes are inserted are formed on the side surface of the base. The heat sink having a flat plate heat pipe according to claim 2, wherein a plurality of grooves in which the flat plate heat pipe is fitted are formed on a lower surface of the base. A flat pipe in which a phase change working fluid is injected sealed; It consists of a wick sintered and molded in the inside of the flat pipe so that the working fluid evaporates, moves, condenses, and reflux along the longitudinal direction of the flat pipe, and the wick is formed with a plurality of channels for guiding the movement of the steam. Each of the channels is provided with a plurality of heat pipes arranged in parallel along the transverse direction of the flat pipe, And a reservoir communicating with the channel of each of the heat pipes is provided at one end of the heat pipes arranged in parallel. A flat pipe in which a phase change working fluid is injected sealed; It consists of a wick sintered and molded in the inside of the flat pipe so that the working fluid evaporates, moves, condenses, and reflux along the longitudinal direction of the flat pipe, and the wick is formed with a plurality of channels for guiding the movement of the steam. Each of the channels is provided with a plurality of heat pipes arranged in parallel along the transverse direction of the flat pipe, and a reservoir communicating with the channels of each of the heat pipes is provided at one end of the heat pipes arranged in parallel. The assembly of flat heat pipes, Bass, A plurality of heat dissipation fins installed on an upper surface of the base, A plurality of recesses formed on a lower surface of the base and having one side open to install the flat heat pipe; And a seating portion formed on the bottom surface of the base to seat the reservoir.