Abstract:
A heat-dissipating unit having a hydrophilic compound film and a method for depositing a hydrophilic compound film are disclosed. The heat-dissipating unit includes a metallic body having a chamber and a working fluid. The chamber has a liquid-guiding structure constituted of an evaporating portion, a condensing portion and a connecting portion. At least one hydrophilic compound film is coated on surfaces of the chamber and the liquid-guiding structure. By this arrangement, the flowing of the working fluid in the heat-dissipating unit is enhanced to improve the heat-conducting efficiency of the heat-dissipating unit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a heat-dissipating unit having a hydrophilic compound film and a method for depositing a hydrophilic compound film, and in particular to a heat-dissipating unit having a hydrophilic compound film with an improved heat-conducting efficiency and a method for depositing such a hydrophilic compound film. 
     2. Description of Prior Art 
     Since the operating speed of a modern electronic apparatus becomes higher, more heat is generated by the electronic apparatus and accumulated therein to raise its operating temperature. Thus, people pay more attention to the heat dissipation of electronic elements and chips because the electronic apparatus may break down or overheat if the heat accumulated therein cannot be dissipated to the outside efficiently. 
     Thus, people try to mount a heat sink, a heat-dissipating module or a fan on the electronic elements and chips for heat dissipation. Further, people also like to use heat pipes because they are very effective in heat conduction. The heat pipe is made of copper or aluminum material. The interior of the heat pipe is provided with a chamber. A wick structure is formed on the inner surface of the chamber. One end of the heat pipe is sealed first and a working fluid is filled in the heat pipe through the other end thereof (i.e., the non-sealed end). Then, a degassing process is performed to make the interior of the heat pipe become a vacuum. Finally, the non-sealed end is sealed to form a vacuum sealed chamber. The heat pipe is often made into a tubular pipe or flat pipe. The wick structure within the heat pipe plays an important role in determining the heat-conducting efficiency of the heat pipe. Especially, the flat heat pipe requires the wick structure to have a large capillary force and a small resistance to liquid flow. However, these two properties seem conflicting in terms of the construction of the heat pipe. In order to solve this conflicting problem, the wick structure is usually treated for improving its surface property. In general, the wick structure is surface-treated to have a better wettability to increase the capillary force of the heat pipe. The most effective way is to form nano-scale microstructures on the surface of the wick structure. For example, the nano-scale microstructures may be made by an etching process, in which a chemical solution is used to etch micro-pits on the surface of the wick structure. However, it is uneasy to control the etching rate of such an etching process. Further, the pollution of the chemical solution is also troublesome. 
     Taiwan Patent Publication No. I292028 discloses a heat pipe and a method for manufacturing the same. The heat pipe includes a hollow tubular casing having two sealed ends. The inner surface of the hollow tubular casing is formed with a liquid-absorbing core. The surface of the liquid-absorbing core is formed with a hydrophilic coating. A liquid fluid is filled in the liquid-absorbing core and sealed in the hollow tubular casing. The hydrophilic coating includes nano-TiO 2 , nano-ZnO, nano-Al 2 O 3  or the mixture thereof. The thickness of the hydrophilic coating is in a range of 10 to 200 nanometers, preferably 20 to 50 nanometer. 
     This patent document discloses a heat-conducting coating formed on the outer surface of the hollow tubular casing. The heat-conducting coating includes a nano-scale film made of carbon, copper, aluminum, or copper-aluminum alloy. The thickness of the heat-conducting coating is in a range of 10 to 500 nanometers, preferably 20 to 300 nanometers. 
     The liquid-absorbing core includes nano-scale carbon balls or carbon fibers. The thickness of the liquid-absorbing core is in a range of 0.1 to 0.5 millimeters, preferably 0.2 to 0.3 millimeters. 
     The method for manufacturing the heat pipe includes the steps of: providing a hollow tubular casing, forming a liquid-absorbing core on inner surfaces of the hollow tubular casing, forming a hydrophilic coating on the surface of the liquid-absorbing core; and sealing a working fluid in the hollowing tubular casing and making the interior of the hollow tubular casing vacuum. 
     The inner and outer surfaces of the hollow tubular casing are surface-treated by a laser texturing process. 
     The hydrophilic coating is made by a vacuum film deposition method. 
     However, the above conventional art has to utilize expensive apparatuses and inevitably increases its production cost. Therefore, it has problems of (1) complicated production, (2) high cost, and (3) expensive facilities. 
     SUMMARY OF THE INVENTION 
     In order to solve the above problems, a primary objective of the present invention is to provide a heat-dissipating unit having a hydrophilic compound film, which is capable of increasing its heat-conducting efficiency. 
     The other object of the present invention is to provide a method for depositing a hydrophilic compound film of a heat-dissipating unit. 
     In order to achieve the above objectives, the present invention is to provide a heat-dissipating unit having a hydrophilic compound film, including: a metallic body having a chamber, the chamber having an evaporating portion, a condensing portion, a connecting portion and a hydrophilic compound film, the interior of the chamber being filled with a working fluid, the evaporating portion being provided in the chamber and having a plurality of first liquid-guiding portions, the first liquid-guiding portions being constituted of a plurality of first liquid-guiding bodies arranged at intervals, at least one first channel being formed between the first liquid-guiding bodies, at least one end of the first channel being a free end connected to a free region, the condensing portion being provided in the chamber opposite to the evaporating portion, the interior of the condensing portion having a plurality of second liquid-guiding portions, the second liquid-guiding portions being constituted of a plurality of liquid-guiding bodies arranged at intervals, at least one second channel being formed between the second liquid-guiding bodies, the connecting portion being provided between the evaporating portion and the condensing portion, the connecting portion having at least one communication hole set and at least one second communication hole set, the first and second communication hole sets being in communication with the evaporating portion and the condensing portion, the hydrophilic compound film being coated on the evaporating portion, the condensing portion, the connecting portion, and the surface of the chamber. 
     The present invention further provides a method for depositing a hydrophilic compound film of a heat-dissipating unit, including steps of: providing a heat-dissipating unit having a chamber and a liquid-guiding structure, and coating at least one hydrophilic compound film on the surfaces of the chamber and the liquid-guiding structure of the heat-dissipating unit. 
     Since the surfaces of the chamber and the liquid-guiding structure of the heat-dissipating unit are deposited with at least one hydrophilic compound film, the working fluid can flow in the heat-dissipating unit more smoothly to thereby increase the heat-conducting efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view showing the heat-dissipating unit having a hydrophilic compound film in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is an assembled perspective view showing the heat-dissipating unit having a hydrophilic compound film in accordance with the preferred embodiment of the present invention; 
         FIG. 3  is a cross-sectional view showing the heat-dissipating unit having a hydrophilic compound film in accordance with the preferred embodiment of the present invention; 
         FIG. 4  is a top view showing an evaporating portion of the heat-dissipating unit having a hydrophilic compound film in accordance with a second embodiment of the present invention; 
         FIG. 5  is a bottom view showing a condensing portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the second embodiment of the present invention; 
         FIG. 6  is a top view showing an evaporating portion of the heat-dissipating unit having a hydrophilic compound film in accordance with a third embodiment of the present invention; 
         FIG. 7  is a bottom view showing a condensing portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the third embodiment of the present invention; 
         FIG. 8  is a flow chart showing the method for depositing a hydrophilic compound film of the heat-dissipating unit in accordance with the present invention; and 
         FIG. 9  is a schematic view showing the manufacturing of the hydrophilic compound film of the heat-dissipating unit in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The above objectives and structural and functional features of the present invention will be described in more detail with reference to preferred embodiments thereof shown in the accompanying drawings 
     Please refer to  FIGS. 1 to 3 .  FIG. 1  is an exploded perspective view showing the heat-dissipating unit having a hydrophilic compound film in accordance with a preferred embodiment of the present invention.  FIG. 2  is an assembled perspective view showing the heat-dissipating unit having a hydrophilic compound film in accordance with the preferred embodiment of the present invention.  FIG. 3  is a cross-sectional view showing the heat-dissipating unit having a hydrophilic compound film in accordance with the preferred embodiment of the present invention. The heat-dissipating unit  1  having a hydrophilic compound unit comprises a metallic body  1   a  having a chamber  11 . The chamber  11  has an evaporating portion  111 , a condensing portion  112 , a connecting portion  113 , and a hydrophilic compound film  4 . The interior of the chamber  11  has a working fluid  2 . 
     The evaporating portion  111 , the condensing portion  112  and the connecting portion  113  define a liquid-guiding structure  11   a.    
     The evaporating portion  111  is provided in the chamber  11 . The evaporating portion  111  has a plurality of first liquid-guiding portions  1111 . The first liquid-guiding portions  1111  are constituted of a plurality of first liquid-guiding bodies  1111   a  arranged at intervals. At least one first channel  1111   b  is formed between the first liquid-guiding bodies  1111   a . At least one end of the first channel  1111   b  is a free end connected to a free region  1111   c . The first liquid-guiding body  1111   a  is formed into an elongate rib. The elongate ribs are arranged transversely at intervals. The first channel  1111   b  is formed between the elongate ribs. A guiding portion  114 , including a first guiding element  1141  and a second guiding element  1142 , is formed between the first liquid-guiding bodies  1111   a  and the at least one first channel  1111   b  and the free region  1111   c  and defines gradual narrow channels. 
     The condensing portion  112  is provided in the chamber  11  opposite to the evaporating portion  111 . The interior of the condensing portion  112  has a plurality of second liquid-guiding portions  1121 . The second liquid-guiding portions  1121  are constituted of a plurality of second liquid-guiding bodies  1121   a  arranged at intervals. At least one second channel  1121   b  is formed between the second liquid-guiding bodies  1121   a . The second liquid-guiding body  1121   a  is formed into an elongate rib. The elongate ribs are arranged transversely at intervals. The first channel  111   b  is formed between the elongate ribs. 
     The connecting portion  113  is provided between the evaporating portion  111  and the condensing portion  112 . The connecting portion  113  has at least one first communication hole set  1131  and at least one second communication hole set  1132 . The first communication hole set  1131  and the second communication hole set  1132  are in communication with the evaporating portion  111  and the condensing portion  112 . 
     The hydrophilic compound film  4  is coated on the evaporating portion  111 , the condensing portion  112 , the connecting portion  113  and the surface of the chamber  11 . 
     The hydrophilic compound film  4  may be any one of oxides or sulfides. The oxides may be any one selected from a group including SiO 2 , TiO 2 , Al 2 O 3 , ZrO 2 , CaO, K 2 O, ZnO. 
     The heat-dissipating unit  1  may be any one of a vapor chamber, a flat heat pipe, and a loop heat pipe. In the present embodiment, a vapor chamber is used as an example, but the heat-dissipating unit  1  is not limited thereto. 
     The metallic body  1   a  is any one selected from a group including copper, aluminum, nickel and stainless steel. 
     Please refer to  FIGS. 4 and 5 .  FIG. 4  is a top view showing the evaporating portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the second embodiment of the present invention, and  FIG. 5  is a bottom view showing the condensing portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the second embodiment of the present invention. The structural relationship among the components of the second embodiment is substantial to that of the first embodiment, so that the redundant description is omitted for simplicity. The difference between the second embodiment and the first embodiment lies in that: the first liquid-guiding bodies  111   a  are longitudinally arranged at intervals. The second liquid-guiding portions  1121   a  are longitudinally arranged at intervals. 
     Please refer to  FIGS. 6 and 7 .  FIG. 6  is a top view showing an evaporating portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the third embodiment of the present invention, and  FIG. 7  is a bottom view showing a condensing portion of the heat-dissipating unit having a hydrophilic compound film in accordance with the third embodiment of the present invention. The structural relationship among the components of the third embodiment is substantial to that of the second embodiment, so that the redundant description is omitted for simplicity. The difference between the third embodiment and the second embodiment lies in that: the first liquid-guiding bodies  111   a  and the second liquid-guiding bodies  1121   a  are provided with a plurality of pits  115 . The pits  115  may be each shaped as a circle, square, triangle or other shape. In the present embodiment, each of the pits  115  is shaped as a fish-scale shape, but it is not limited thereto. 
     Please refer to  FIGS. 8 and 9 .  FIG. 8  is a flow chart showing the method for depositing a hydrophilic compound film of the heat-dissipating unit in accordance with the present invention, and  FIG. 9  is a schematic view showing the manufacturing of the hydrophilic compound film of the heat-dissipating unit in accordance with the present invention. Please also refer to  FIGS. 1 to 7 . The method for depositing a hydrophilic compound film of the heat-dissipating unit includes a step S 1  of providing a heat-dissipating unit having a chamber and a liquid-guiding structure, and a step S 2  of coating at least one hydrophilic compound film on surfaces of the chamber and the liquid-guiding structure of the heat-dissipating unit. 
     In the step S 1 , a heat-dissipating unit  1  having a chamber  11  and a liquid-guiding structure  11   a  is provided. The heat-dissipating unit  1  may be a heat-pipe, a vapor chamber, a flat heat pipe, a loop heat pipe or the like. In the present embodiment, the vapor chamber is used as an example of the heat-dissipating unit  1 , but it is not limited thereto. 
     In the step S 2 , the surfaces of the chamber  11  and the liquid-guiding structure  11   a  are coated with at least one hydrophilic compound film  4 . The hydrophilic compound film  4  may be oxides or sulfides. The oxides may be any one selected from a group including SiO 2 , TiO 2 , Al 2 O 3 , ZrO 2 , CaO, K 2 O and ZnO. In the present embodiment, the hydrophilic compound film  4  is made of Al2O3, but it not limited thereto. 
     In the heat-dissipating unit  1  of the present invention, the hydrophilic compound film  4  is made by a physical vapor deposition method (PVD) and a sol gel method. In the present embodiment, the sol gel method is used as an example, but it is not limited thereto. The sol gel method may be performed by a precipitating, spin coating, brushing, wetting or soaking process. In the present embodiment, the soaking process is used as an example of the sol gel method for coating the hydrophilic compound film  4 , but the soaking process is not limited thereto. In the sol gel method, Al2O3 particles are soaked in an aqueous solution  5 . The aqueous solution  5  and the Al2O3 particles are poured in a tank  6  and dispersed therein uniformly. A portion of the heat-dissipating unit  1  having the liquid-guiding structure  11   a  is soaked in the aqueous solution  5  of the tank  6 . Then, the heat-dissipating unit  1  is disposed in the aqueous solution  5  of the tank  6 . Finally, the heat-dissipating unit  1  is taken out of the aqueous solution  5  or the aqueous solution  5  is drained from the tank  6  in such a manner that the Al 2 O 3  particles are adhered to the surface of the liquid-guiding structure  11   a  ( FIG. 9 ). 
     The heat-dissipating unit  1  mentioned in the previous embodiments may be any one of a vapor chamber, a flat heat pipe and a loop heat pipe.