TW201331540A - Heat transfer device made of conductive plastic and manufacturing method thereof - Google Patents

Abstract

A heat transfer device made of conductive plastic and a manufacturing method thereof are provided. The heat transfer device includes a shell and an operating fluid. The shell has a heat absorbing end and a heat dissipation end, and the heat absorbing end is configured to be contacted with a heat source. The shell has a first containing room which is isolated from the outside environment and the operating fluid is filled in the first containing room. When the heat is absorbed by the operating fluid, the operating fluid is transformed from a liquid into a gas, and the gaseous operating fluid is transferred into the heat dissipation end.

Description

Heat sink made of heat conductive plastic and manufacturing method thereof

The present invention relates to a heat dissipating device and a method of manufacturing the same, and more particularly to a heat dissipating device made of a thermally conductive plastic and a method of manufacturing the same.

In recent years, the speed of advancement of information technology can be said to be quite fast, especially in terms of the computing speed of electronic components such as a central processing unit (CPU) and the number of transistors in the connotation. Also, because the computing speed of the central processing unit is quite high, the waste heat generated by the associated processor is also quite large. In order for the central processor to work properly at the allowed temperatures, a well-designed heat sink or thermal module plays an important role.

At present, the heat sink is used in most of the heat dissipation modules, and the heat sink is placed above the electronic components so that the waste heat generated by the electronic components can be smoothly eliminated. For an electronic component having a lower heat dissipation requirement, the heat sink disposed thereon is made of, for example, aluminum. For electronic components (such as CPUs) that require high heat dissipation, the heat sinks disposed thereon are, for example, made of copper having a higher thermal conductivity.

However, the current price of metals on the market has been on the rise, which will make the burden on manufacturers more and more important. Therefore, some skilled in the art will use a thermally conductive plastic to fabricate the heat sink. The thermal conductive plastic is made of a general plastic material and is filled with some metal oxide powder, carbon fiber, or ceramic powder in the plastic. The thermal conductivity ranges from 1 to 20 W/mK, which is about the traditional value. 5-100 times plastic. However, even so, the thermal conductivity of the thermally conductive plastic is still much smaller than aluminum (thermal conductivity of about 240W / m-K) and copper (thermal conductivity of about 400W / m-K), so the application range of thermal plastics is still quite limited.

Therefore, how to design a heat dissipating device or a heat dissipating module, which has high heat dissipation efficiency and low cost, is worthy of consideration by those who have ordinary knowledge in the field.

It is an object of the present invention to provide a heat sink that has high heat dissipation efficiency and low cost.

In accordance with the above and other objects, the present invention provides a heat sink comprising a housing and a working fluid. The housing has a heat absorbing end and a heat dissipating end, and the heat absorbing end is adapted to be in contact with the heat source, and the first accommodating space is sealed inside the housing. The working fluid is filled in the first accommodating space. When the heat generated by the heat source is absorbed by the working fluid, the working fluid is converted from the liquid into the gas, and the gaseous working fluid flows to the heat radiating end.

In the above heat dissipating device, the heat dissipating end of the housing protrudes outwardly from the plurality of extending housings, the extension housing has a second accommodating space therein, and the second accommodating space communicates with the first accommodating space, and the extending shell The body is made of a thermally conductive plastic.

In the above heat sink, the inner wall of the extension housing is provided with a plurality of grooves.

In the above heat sink, the inner wall of the housing is provided with a plurality of grooves.

In the above heat dissipating device, a plurality of drainage columns are disposed in the first accommodating space, and the drainage column is connected between the heat absorbing end of the casing and the heat dissipating end of the casing.

The invention provides a method for manufacturing a heat dissipating device, which has high heat dissipation efficiency and low cost. The manufacturing method of the heat sink includes:

(a) making the first casing by injection molding;

(b) making a second casing by injection molding;

(c) combining the first housing and the second housing to form a housing having a first accommodating space inside, and having an injection hole on the housing;

(d) injecting a working fluid from the injection hole into the first accommodating space while simultaneously extracting air in the first accommodating space through the injection hole;

(e) closing the injection hole;

Wherein, the first housing and the second housing are both made of heat conductive plastic.

In the above method of manufacturing the heat sink, the step (c) is to combine the first casing and the second casing by means of high-frequency fusion.

In summary, the heat sink of the present invention has the following advantages:

(1) The housing of the heat sink is made of heat-conductive plastic, so the material cost is reduced. Moreover, the inside of the casing is sealed with a fluid which changes phase after heat absorption, so that it has good heat dissipation efficiency;

(2) The housing of the heat sink is made by injection molding, and the required operating temperature is low, so the manufacturing cost is low;

(3) Since the heat dissipating device is made of a heat conductive plastic, the heat dissipating device of the present invention can have more variations in appearance than the conventional heat dissipating device;

(4) Since the heat sink housing is made of a thermally conductive plastic and only a certain amount of working fluid is added to the interior of the housing, the heat sink of the present invention is lighter than conventional heat sinks;

(5) With the heat sink of the present invention, the heat conductive plastic can be widely used.

The above described features and advantages of the present invention will be more apparent from the following description.

Please refer to FIG. 1A and FIG. 1B . FIG. 1A illustrates a first embodiment of a heat sink according to the present invention, and FIG. 1B illustrates a cross-sectional view of the heat sink. The heat dissipation device 100 of the embodiment is adapted to be disposed on a heat source 20 to dissipate heat from the heat source 20 . The heat source 20 is, for example, a central processing unit in a computer system, a north bridge wafer, a south bridge wafer, or other heat generating components. In the embodiment, the heat sink 100 includes a housing 110 and a working fluid 130. In this embodiment, the housing 110 includes a first housing 112 and a second housing 114, and one end of the housing 110 adjacent to the heat source 20 is a heat absorption end 110a, and the end of the housing 110 away from the heat source 20 is It is the heat dissipation end 110b. In addition, the housing 110 is internally sealed with a first accommodating space 116, and the working fluid 130 is filled in the first accommodating space 116, that is, the first accommodating space 116 is isolated from the external environment, and the working fluid 130 is not Will spread to the outside world. In the present embodiment, the working fluid 130 is water, but a person having ordinary knowledge in the art may also use a liquid having a higher latent heat such as ethanol as the working fluid 130.

In addition, the housing 110 is made of a heat-conductive plastic made of a general plastic material and filled with some metal oxide powder, carbon fiber, or ceramic powder. For example, polyphenylene sulfide (PPS) can be mixed with a plurality of large particles of magnesium oxide to form an insulating heat conductive plastic. The thermal conductivity of general plastics is only 0.2W/m-K, while the thermal conductivity of typical thermal plastics ranges from 1-20W/m-K. This value is about 5-100 times that of traditional plastics. In addition, since the heat conductive plastic is added with a material having a high hardness such as metal oxide powder, carbon fiber, or ceramic powder, the strength of the heat conductive plastic is higher than that of the general plastic. Moreover, the thermal conductive plastic has higher ductility than the general plastic.

Referring to FIG. 1A and FIG. 1B , in the embodiment, a plurality of extension housings 120 are further extended on the heat dissipation end 110 b of the housing 110 , and the extension housing 120 is also made of a heat conductive plastic. Moreover, the second housing space 122 is connected to the first receiving space 116, but is isolated from the external environment. When the heat source 20 generates heat, the heat is transmitted to the working fluid 130 through the casing 110, and the liquid working fluid 130 is evaporated, and the gaseous working fluid 130 flows toward the heat radiating end 110b, so the gas flows. The working fluid 130 flows back into the second accommodating space 122 of the extension housing 120. In FIG. 1B, the arrow represents the flow direction of the gaseous working fluid 130. By the temperature difference from the external environment, the working fluid 130 will discharge the heat outward and condense into a liquid, and then return to the endothermic end 110a.

Please refer to FIG. 1C. FIG. 1C is an exploded view of the heat sink of the present invention. As can be seen in Figure 1C, the inner wall of the second housing 114 is provided with a plurality of grooves 118 which assist in the flow of the liquid working fluid 130. Moreover, it will be apparent from the foregoing that those skilled in the art will appreciate that grooves may also be provided in the inner walls of the first housing 112 and the extension housing 120.

As can be seen from the above, the thermal conductivity (1-20 W/mK) of the thermally conductive plastic is lower than that of aluminum (thermal conductivity of about 240 W/mK) and copper (thermal conductivity of about 400 W/mK), but is absorbed by the phase change of the working fluid 130. The heat dissipation of the heat sink 100 as a whole is higher than that of the heat sink made entirely of metal. According to the experiments of the inventors of the present application, in the case of the same size and shape, the heat dissipation efficiency of the heat sink 100 can be up to five times higher than that of the heat sink made entirely of aluminum. In addition, the material cost of the thermally conductive plastic and the working fluid 130 is lower than that of the metal (especially copper). Moreover, since the heat dissipating device 100 of the present embodiment is mainly made of a heat conductive plastic, and the inside of the heat dissipating device 100 is hollow, the density is 1/5 of the heat dissipating device made entirely of copper, and thus the heat dissipating device 100 The weight is also lighter, which is more convenient for carrying and handling, and also conforms to the current trend of light weight of electronic devices. In addition, since the heat conductive plastic is an insulating material, the risk of electric leakage is relatively less than that of the conventional heat sink made of metal. Moreover, the thermal expansion coefficient of the thermally conductive plastic is lower than that of copper or aluminum, so that the heat dissipation device 100 of the present invention has a small change in volume after being heated, so that it does not interfere with other components in the electronic device.

In addition, the manufacturing cost of the heat sink 100 is also lower than that of the conventional heat sink made of metal. The manufacturing flow of the heat sink 100 will be described below. Please refer to FIG. 2 at the same time, and FIG. 2 illustrates the manufacturing process of the heat sink. First, the first housing 112 and the second housing 114 are respectively formed by plastic injection molding, and an injection hole (not shown) is formed on the first housing 112, for example. Next, referring to step S120, the first housing 112 and the second housing 114 are combined by high-frequency hot melt to form the housing 110. Then, referring to step S130, the working fluid 130 is injected into the first accommodating space 116 from the injection hole while the air in the first accommodating space 116 is evacuated through the injection hole. Thereafter, referring to step S140, the injection hole is closed, so that the manufacture of the heat sink 100 is completed.

It should be noted that in the process of manufacturing the heat sink 100, the first housing 112 and the extension housing 120 are simultaneously formed. Moreover, in step S140, the injection hole may be closed by high-frequency hot melt, or a small piece of metal may be welded at the injection hole to close the injection hole.

It can be seen from the above that the housing 110 of the heat dissipating device 100 is made by plastic injection molding, and the working temperature involved is lower than that of using die casting or powder metallurgy, so the manufacturing cost thereof is lower than the conventional heat sink. low. Moreover, since the housing 110 is made of a thermally conductive plastic, there are many variations in the outer shape. For example, in FIG. 1A, the extension housing 120 is cylindrical, but those of ordinary skill in the art may also make other shapes, such as curved wings, to enhance aesthetics.

Please refer to FIG. 3. FIG. 3 is a cross-sectional view showing a second embodiment of the heat sink according to the present invention. In the heat sink 100' of FIG. 3, the same or similar elements as those in the heat sink 100 will be denoted by the same reference numerals and will not be described again. In the first accommodating space 116 of the heat dissipating device 100 ′, a plurality of drainage columns 113 are disposed in the first accommodating space 116 of the heat dissipating device 100 ′. The drainage columns 113 are connected to the heat absorbing end 110 a of the housing 110 and the housing. The heat dissipation ends 110b, that is, between the first housing 112 and the second housing 114 are disposed. With these drainage columns 113, it is advantageous for the working fluid to flow back to the heat absorption end 110a.

Please refer to FIG. 4. FIG. 4 is a cross-sectional view showing a third embodiment of the heat sink according to the present invention. In FIG. 4, the heat sink 200 is in the form of a sealed circular tube. The heat sink 200 includes a housing 210 and a working fluid 230. The housing 210 is composed of a first housing 212 and a second housing 214. The housing 210 has a heat absorption end 210a and a heat dissipation end 210b, wherein the heat absorption end 210a is in contact with the heat source 20. In this embodiment, the heat sink 200 can be used to replace the conventional heat pipe. Since the housing 210 of the heat sink 200 is also made of a heat conductive plastic, the heat sink 200 has lower cost, lighter weight, and is easier to manufacture. advantage.

In addition, it should be noted that the heat dissipating device 100 of FIG. 1A and the heat dissipating device 200 of FIG. 2 can be used together in addition to being separately usable. The heat dissipating device 100 can be placed, for example, at the heat absorbing end of the heat dissipating device 200 and the heat generating source 20 . between.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

20. . . Heat source

100, 100’. . . Heat sink

110. . . case

110a. . . Endothermic end

110b. . . Heat sink

112. . . First housing

113. . . Drain column

114. . . Second housing

116. . . First accommodation space

118. . . Trench

120. . . Extension housing

122. . . Second accommodation space

130. . . Working fluid

200. . . Heat sink

210. . . First housing

220. . . Second housing

210a. . . Hot end

210b. . . Hot end

FIG. 1A illustrates a first embodiment of a heat sink of the present invention.

FIG. 1B is a cross-sectional view of the heat sink.

FIG. 1C is an exploded view of the heat sink of the present invention.

FIG. 2 illustrates a manufacturing process of the heat sink.

3 is a cross-sectional view showing a second embodiment of the heat sink of the present invention.

4 is a cross-sectional view showing a third embodiment of the heat sink of the present invention.

20. . . Heat source

100. . . Heat sink

110. . . case

110b. . . Heat sink

110a. . . Endothermic end

112. . . First housing

114. . . Second housing

116. . . First accommodation space

120. . . Extension housing

122. . . Second accommodation space

130. . . Working fluid

Claims (7)

A heat dissipating device is adapted to be in contact with a heat generating device, the heat dissipating device comprising: a casing having a heat absorbing end and a heat dissipating end, the heat absorbing end being adapted to be in contact with the heat source, and the shell The inner portion of the body is sealed with a first accommodating space; and a working fluid is filled in the first accommodating space. When the heat generated by the heat generating source is absorbed by the working fluid, the working fluid changes from the liquid The gas is formed into a gas, and the working fluid flows to the heat radiating end; wherein the casing is made of a heat conductive plastic. The heat dissipation device of claim 1, wherein the heat dissipation end of the housing protrudes outwardly from the plurality of extension housings, the extension housing has a second receiving space therein, and the second housing space is The first accommodating space is in communication, and the extension housing is made of a heat conductive plastic. The heat dissipating device of claim 2, wherein the inner wall of the extension housing is provided with a plurality of grooves. The heat sink according to any one of claims 1 to 3, wherein the inner wall of the casing is provided with a plurality of grooves. The heat dissipating device according to any one of the preceding claims, wherein the first accommodating space is provided with a plurality of drainage columns, the drainage column being connected to the heat absorbing end of the casing and Between the heat dissipation ends of the housing. A method of manufacturing a heat dissipating device, comprising: (a) fabricating a first casing by injection molding; (b) fabricating a second casing by injection molding; (c) forming the first casing with the The second housing is combined to form a housing having a first accommodating space therein, and the housing has an injection hole; (d) injecting a working fluid from the injection hole to the first And accommodating the air in the first accommodating space through the injection hole; and (e) closing the injection hole; wherein the first housing and the second housing are both Made of thermal plastic. The method of manufacturing a thermal device according to claim 6, wherein in the step (c), the first casing and the second casing are combined by means of high-frequency fusion.