Abstract:
Provided is a heat cooler configured to rapidly cool a heat-generating device by transferring heat generated from the heat-generating device to an outside area. The heat cooler includes a heat conductive body having a predetermined volume and sealing members. The body includes a plurality of penetration holes formed through top and bottom surfaces of the body. The sealing members are hermetically coupled to the top and bottom surfaces of the body. The bores are sealed with the sealing members to form independent accommodation portions, and a plurality of heat conductive beads and a refrigerant are filled in the accommodation portions in a state where the refrigerant permeates between the heat conductive beads.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority benefit of Korean Patent Application No. 10-2010-0049375 filed May 26, 2010 and Korean Patent Application No. 10-2010-0056701 filed Jun. 15, 2010, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a heat cooler for cooling a heat-generating electronic device, and more particularly, to a heat cooler configured to rapidly cool a heat-generating device by dissipating heat generated from the heat-generating device to an outside area. 
       BACKGROUND OF THE INVENTION 
       [0003]    Heat pipes, heat spreaders, and heat sinks having good heat conduction, dissipation, and diffusion characteristics have been used individually or in combination for rapidly cooling heat-generating devices of electronic apparatuses. 
         [0004]    In the electronic industry, capillary coolers such as heat pipes and heat spreaders are used to transfer heat to outside areas by utilizing the capillary phenomenon. For example, a refrigerant such as distilled water is circulated in a vacuum-state heat pipe or heat spreader so as to rapidly dissipate heat generated from a heat-generating device such as a microprocessor. 
         [0005]    In a metal heat pipe of the related art, a plurality of grooves are formed in the inner wall of the metal heat pipe, and distilled water is moved in a vacuum state along the grooves so as to cause the distilled water to evaporate for rapidly transferring heat to a low-temperature region. The surface area of the inner wall of the metal heat pipe is varied according to the size and number of the grooves formed in the inner wall of the metal heat pipe, and the heat-transfer ability of the metal heat pipe is determined by the size of the surface area of the inner wall of the metal heat pipe. However, it is difficult to adjust the size and number of the grooves due to structural or manufacturing difficulties. 
         [0006]    Moreover, since the grooves are formed only in the inner wall of the metal heat pipe, the inner surface area of the metal heat pipe is not sufficient large for rapidly transferring heat using a medium such as distilled water. 
         [0007]    In addition, since the inside of the metal heat pipe is hollow, heat dissipation through the metal heat pipe is not sufficient. 
         [0008]    In another kind of metal heat pipe of the related art, a plurality of wicks formed of copper wires by weaving or braiding are disposed in the metal heat pipe, and distilled water is moved in a vacuum state between the copper wires of the wicks by the capillary phenomenon so as to cause the distilled water to evaporate for rapidly transferring heat to a low-temperature region. 
         [0009]    In this case, however, it is difficult to insert many copper-wire wicks in the metal heat pipe. Therefore, the inner surface area of the metal heat pipe is also insufficient for rapidly transferring heat using a medium such as distilled water. 
         [0010]    As described above, heat pipes of the related art are limited in increasing their inner surface areas. Furthermore, it is difficult to manufacture heat pipes of the related art. 
         [0011]    In addition, heat pipes of the related art have low heat conductivity because materials having high heat conductivity are not sufficiently used. 
         [0012]    In addition, since the inner space of a heat pipe of the related art is filled with, for example, a refrigerant, a vacuum space, and a wick, the heat conductivity of the heat pipe is not high, and efficient cooling using the properties of latent heat and specific heat cannot be carried out. 
         [0013]    Therefore, in the related art, for example, a heat sink having high heat conductivity is used together with a circular-pipe shaped or plate-shaped heat pipe having good heat diffusion characteristics but insufficient heat conductivity. 
         [0014]    For example, a heat sink constituted by only a metal body having high heat conductivity is used in the related art. 
         [0015]    Such a heat sink is relatively large and has high heat conductivity. The heat sink is attached to a heat-generating device to dissipate heat generated from the heat-generating device to the atmosphere. 
         [0016]    Although the heat sink has high heat conductivity, heat diffusion through the heat sink is not satisfactory. Moreover, the heat sink has limitation due to its thick thickness and heavy weight. 
         [0017]    Therefore, an electronic device which is slim but generates a large amount of heat, such as a central processing unit (CPU) of a laptop computer, is cooled by using both a compact heat pipe having a high heat diffusion rate and a relatively large heat sink having a high heat conduction rate. The heat pipe is attached to the topside of the electronic device, and heat generated from the electronic device is transferred through the heat pipe to the relatively large heat sink. 
         [0018]    Therefore, what is needed is an inexpensive thin heat cooler that has high heat diffusion and conduction rates and can be easily used regardless of installation environments. 
       SUMMARY OF THE INVENTION 
       [0019]    An object of the present invention is to provide a heat cooler having high heat diffusion and conduction rates and configured to be easily adjusted in heat diffusion and conduction rates. 
         [0020]    Another object of the present invention is to provide a heat cooler having high heat diffusion and conduction rates by increasing the inner surface area of a metal pipe to facilitate circulation of a refrigerant by the capillary phenomenon. 
         [0021]    Another object of the present invention is to provide a heat cooler having high heat diffusion and conduction rates by using latent heat and specific heat of heat conductive beads. 
         [0022]    Another object of the present invention is to provide a heat cooler having high heat diffusion and conduction rates in the scale of micrometers. 
         [0023]    Another object of the present invention is to provide a thin heat cooler that can be easily fabricated. 
         [0024]    Another object of the present invention is to provide an efficient heat cooler that has good cooling ability and can be easy used in various application conditions. 
         [0025]    Another object of the present invention is to provide a heat cooler having uniform heat diffusion and conduction rates regardless of the installation position of the heat cooler. 
         [0026]    According to an aspect of the present invention, there is provided a heat cooler including: a heat conductive body having a predetermined volume, the body including a plurality of bores formed through top and bottom surfaces of the body; and sealing members hermetically coupled to the top and bottom surfaces of the body, wherein the bores are sealed with the sealing members to form independent accommodation portions, and a plurality of heat conductive beads and a refrigerant are filled in the accommodation portions in a state where the refrigerant permeates between the heat conductive beads. 
         [0027]    According to another aspect of the present invention, there is provided a heat cooler including: a heat conductive body having a predetermined volume, the body including a plurality of bores formed through top and bottom surfaces of the body; and sealing members hermetically coupled to the top and bottom surfaces of the body, wherein the bores are connected to each other through a gap formed between one of the sealing members and the top surface or the bottom surface of the body, a plurality of heat conductive beads and a refrigerant are filled in the bores in a state where the refrigerant permeates between the heat conductive beads, and the refrigerant is allowed to flow horizontally among the bores through the gap. 
         [0028]    According to another aspect of the present invention, there is provided a heat cooler including: a heat conductive body having a predetermined volume, the body including a plurality of accommodation grooves formed in one of top and bottom surfaces of the body; and a sealing member hermetically coupled to the one of the top and bottom surfaces of the body, wherein a plurality of heat conductive beads and a refrigerant are filled in the accommodation grooves in a state where the refrigerant permeates between the heat conductive beads. 
         [0029]    According to another aspect of the present invention, there is provided a heat cooler including: a sealing member attached to a heat-generating device to receive heat from the heat-generating device; and a heat conductive body hermetically coupled to a top surface of the sealing member, wherein a plurality of hollow protrusions are formed in one piece with the body and are independently sealed with the sealing member, and a plurality of heat conductive beads and a refrigerant are filled in the hollow protrusions in a state where the refrigerant permeates between the heat conductive beads. 
         [0030]    According to another aspect of the present invention, there is provided a heat cooler including: a heat conductive body having a one-piece pipe shape and sealed with sealing members at both ends thereof; a heat conductive beads filled in the body; and a refrigerant filling gaps formed between the heat conductive beads. 
         [0031]    According to another aspect of the present invention, there is provided a heat cooler including: a one-piece heat conductive body including a plurality of longitudinal independent penetration holes positioned close to each other; sealing members disposed on both ends of the body to seal the penetration holes; a plurality of heat conductive beads filled in the penetration holes; and a refrigerant filling gaps formed between the heat conductive beads. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The above objects and other advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which: 
           [0033]      FIG. 1  is an exploded perspective view illustrating a heat cooler according to an embodiment of the present invention; 
           [0034]      FIG. 2  is an assembled perspective view of  FIG. 1 ; 
           [0035]      FIGS. 3A and 3B  are views illustrating heat coolers  110  and  120  modified from the heat cooler of  FIG. 1 ; 
           [0036]      FIG. 4  is a sectional view illustrating an inside of the heat cooler of  FIG. 1 ; 
           [0037]      FIG. 5  is a sectional view illustrating an inside of the heat cooler of  FIG. 3A ; 
           [0038]      FIG. 6  is a view illustrating an application example of the heat cooler of  FIG. 1 ; 
           [0039]      FIG. 7  is a view illustrating another application example of the heat cooler of  FIG. 1 ; 
           [0040]      FIG. 8  is a sectional view illustrating a heat cooler according to another embodiment of the present invention; 
           [0041]      FIG. 9  is a plan view illustrating the heat cooler of  FIG. 8 ; 
           [0042]      FIG. 10  is a perspective view illustrating a heat cooler according to another embodiment of the present invention; and 
           [0043]      FIG. 11  is a perspective view illustrating a heat cooler according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Exemplary embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. 
         [0045]      FIG. 1  is an exploded perspective view illustrating a heat cooler  100  according to an embodiment of the present invention, and  FIG. 2  is an assembled perspective view illustrating the heat cooler  100  of  FIG. 1 . 
         [0046]    The heat cooler  100  includes a body  20  and metal foils  10  and  30  attached to the top and bottom surfaces of the body  20  to seal the body  20 . At least one of the top and bottom surfaces of the heat cooler  100  is a horizontal surface. 
         [0047]    The body  20  has a one-piece sheet shape with a uniform thickness, and a plurality of separate bores  22  are formed through the top and bottom surfaces of the body  20 . The body  20  is formed of one of a metal, a ceramic material, graphite, and carbon that have good heat conductivity and heat dissipation and diffusion characteristics. The body  20  has a thickness in the range from about 0.3 mm to about 20 mm. 
         [0048]    For example, the body  20  may be formed of graphite to rapidly diffuse generated from a heat-generating device in a horizontal direction. In this case, however, the manufacturing process of the body  20  may be difficult, and the manufacturing cost of the body  20  may be increased. 
         [0049]    The bores  22  may be formed using a press, a laser, or a mold. In this case, the bores  22  may be easily formed with low costs. The bores  22  may have the circular cross section and diameter so that the bores  22  can be easily formed with low costs. For example, the bores  22  may have a diameter of 0.3 mm to 3 mm. 
         [0050]    In  FIG. 1 , the bores  22  are independently formed. However, the present invention is not limited thereto. For example, as shown in  FIG. 7 , a gap may be formed between the body  20  and the metal foil  10  such that a region of the body  20  where the bores  22  are formed is lower than the other region of the body  20 . In this case, a refrigerant may flow horizontally between neighboring bores  22  through the gap. 
         [0051]    In the embodiment shown in  FIG. 1 , since the bores  22  form independently sealed spaces, the heat conduction and diffusion rates of the heat cooler  100  may be substantially uniform regardless of the position of a device where the heat cooler  100  is attached. For example, the positions of heat conductive beads  24  and a refrigerant  25  filled in the bores  22  may be varied according to whether a device to which the heat cooler  100  is attached is erected or laid, and thus the heat diffusion and conduction rates of the heat cooler  100  may be locally varied. However, such variations may not be large because the bores  22  are independently provided. 
         [0052]    As shown in  FIG. 2 , the metal foil  10  is bonded to the top surface of the body  20  using a heat conductive adhesive  40 , and the metal foil  30  is bonded to the bottom surface of the body  20  using a heat conductive adhesive  42 . 
         [0053]    The heat conductive adhesives  40  and  42  may include one of heat conductive polymer adhesives, heat conductive elastic rubber adhesives, heat conductive epoxy adhesives, and heat conductive acryl adhesives. If the heat conductive adhesives  40  and  42  include a heat conductive elastic adhesive, the heat conductive adhesives  40  and  42  may be elastic and not deformed by heat after being hardened. Therefore, bonding processes may be easily carried out, and a refrigerant may be reliably sealed. 
         [0054]    A metal cap may be used instead of the metal foil  10 . In addition, soldering or welding such as metal spot welding may be used instead of using the heat conductive adhesives  40  and  42  so as to bond the metal foils  10  and  30 . 
         [0055]    If a welding method is used, heat conduction and diffusion may be improved although manufacturing cost may be increased. If a heat conductive polymer adhesive is used, although heat conduction and diffusion are decreased, bonding processes may be easily carried out, and a refrigerant may be reliably sealed in the bores  22 . 
         [0056]    The thickness of the metal foils  10  and  30  may be equal to or less than ⅓ the thickness of the body  20 . For example, the thickness of the metal foils  10  and  30  may be about 0.12 mm. However, the present invention is not limited thereto. The metal foils  10  and  30  may be formed of one of copper, aluminum, magnesium and an alloy thereof. 
         [0057]      FIGS. 3A and 3B  are views illustrating heat coolers  110  and  120  modified from the heat cooler  100  of  FIG. 1 . 
         [0058]    Referring to  FIG. 3A , the heat cooler  110  includes a body  50  and a metal foil  30  bonded to the body  50  using a heat conductive adhesive  40 . At least one groove  52  formed in the body  50  are opened only at a side facing the metal foil  30 . 
         [0059]    Therefore, the metal foil  30  is bonded to only the bottom surface of the body  50 . The top surface of the body  50  may function as the metal foil  10  of  FIG. 1 . In this case, although it is difficult to form the groove  52 , the heat diffusion rate of the heat cooler  110  can be increased. In addition, the heat conduction efficiency of the heat cooler  110  can be improved. 
         [0060]    Referring to  FIG. 3B , the heat cooler  120  has a structure opposite to that of the heat cooler  110  shown in  FIG. 3A . That is, in the heat cooler  120 , a metal foil  10  is bonded to the top surface of a body  50  using a heat conductive adhesive  40 . A groove  52  (refer to  FIG. 3A ) formed in the body  50  are opened only at sides facing the metal foil  10 . 
         [0061]      FIG. 4  illustrates an inside structure of the bore  22  illustrated in  FIG. 1 , and  FIG. 5  illustrates an inside structure of the groove  52  shown in  FIG. 3A . 
         [0062]    As shown in  FIGS. 4 and 5 , heat conductive beads  24  such as heat conductive powder, heat conductive particles, or heat conductive balls are placed in the bore  22 , and heat conductive beads  54  such as heat conductive powder, heat conductive particles, or heat conductive balls are placed in the groove  52 . A refrigerant  25  such as distilled water is partially or fully filled in the bore  22  to fill gaps between the heat conductive beads  24 , and a refrigerant  55  such as distilled water is partially or fully filled in the groove  52  to fill gaps between the heat conductive beads  54 . 
         [0063]    The heat conductive beads  24  and  54  may be formed of one of a heat conductive metal, a heat conductive ceramic material, heat conductive carbon, and a combination thereof. However, materials that can be used to form the heat conductive beads  24  and  54  are not limited thereto. 
         [0064]    The heat conductive beads  24  may occupy equal to or greater than 30% of the inside volume of the bore  22  to increase the heat diffusion and conduction rates of the heat cooler  100 . The heat conductive beads  54  may occupy equal to or greater than 30% of the inside volume of the groove  52  to increase the heat diffusion and conduction rates of the heat cooler  110  ( 120 ). 
         [0065]    The sizes of the heat conductive beads  24  and  54  may be equal. Alternatively, small beads and relatively large beads may be used together according to the kind and viscosity of a refrigerant. 
         [0066]    If small heat conductive beads  24  and  54  are filled in the bore  22  and the groove  52 , since gaps between the heat conductive beads  24  and  54  are small, heat conduction increases but heat diffusion decreased. On the contrary, if relatively larger heat conductive beads  24  and  54  are filled in the bore  22  and the groove  52 , since gaps between the heat conductive beads  24  and  54  are large, heat diffusion increases but heat conduction decreases. Therefore, the kind, amount, and size of the heat conductive beads  24  and  54  may be properly selected according to desired heat diffusion and conduction rates. 
         [0067]    The sizes of the heat conductive beads  24  may be equal to or smaller than ⅓ the diameter of the bore  22 , and the sizes of the heat conductive beads  54  may be equal to or smaller than ⅓ the diameter of the groove  52 . For example, the sizes of the heat conductive beads  24  and  54  may be in the range from 0.01 mm to 1 mm. 
         [0068]    The refrigerant  25  may be one of a liquid refrigerant, a gas refrigerant, and a mixture thereof, and the refrigerant  55  may be one of a liquid refrigerant, a gas refrigerant, and a mixture thereof. 
         [0069]    As shown in  FIG. 5 , the refrigerant  55  may be partially filled in the groove  52  if the refrigerant  55  is a liquid refrigerant. That is, not all the heat conductive beads  54  are submerged in the refrigerant  55 . 
         [0070]    A material having a relative low boiling point, such as distilled water and alcohol, may be used as a liquid refrigerant. However, the present invention is not limited thereto. A material having a relatively low specific gravity such as helium (He) gas may be used as a gas refrigerant. However, the present invention is not limited thereto. 
         [0071]    Vacuum spaces  26  and  56  may be formed in the bore  22  and the groove  52  for heat diffusion at a low temperature. 
         [0072]    That is, since the pressures of the vacuum spaces  26  and  56  are low, the refrigerants  25  and  55  may be easily evaporated even at a low temperature to facilitate heat diffusion. 
         [0073]    The diameters and heights of the bore  22  and the groove  52  are not limited to specific values as long as the refrigerants  25  and  55  can be circulated between high-temperature regions close to heat sources and low-temperature regions opposite to the high-temperature regions. For example, if the diameters of the bore  22  and the groove  52  are excessively large as compared with the heights of the bore  22  and the groove  52 , high-temperature regions and low temperature regions may not be clearly distinguished in the bore  22  and the heat conductive beads  54 , and thus the refrigerants  25  and  55  may be only in a gas state. 
         [0074]    In the current embodiment, copper beads are placed in the bore  22  and groove  52  as the heat conductive beads  24  and  54 ; distilled wafer is filled in the bore  22  and the groove  52  as the refrigerants  25  and  55 ; and the vacuum spaces  26  and  56  are formed in the bore  22  and the groove  52 . However, the present invention is not limited thereto. 
         [0075]    In the current embodiment, the heat conductive beads  24  and  54  and the refrigerants  25  and  55  are filled in the bore  22  and the groove  52 . However, the present invention is not limited thereto. For example, sol or gel prepared by mixing distilled water with heat conductive beads such as copper, ceramic, or carbon beads may be filled in the bore  22  and the groove  52 . In this case, processes of filling the sol or gel in the bore  22  and the groove  52  may be easily carried out while maintaining the cooling effects. 
         [0076]    As described above, the numbers and sizes of the bores  22  and the grooves  52 , the material and sizes of the heat conductive beads  24  and  54 , and the kind and amount of the refrigerants  25  and  55  may be varied to adjust the heat diffusion and conduction rates of the heat coolers  100 ,  110 , and  120  having predetermined sizes to optimal values. 
         [0077]      FIG. 6  is a view illustrating an application example of the heat cooler  100  of  FIG. 1 . 
         [0078]    The heat cooler  100  of the present invention is placed on a heat-generating device  1  such as a semiconductor chip which is mounted on a circuit board. The heat cooler  100  is placed on the heat-generating device  1  using a heat conductive adhesive  2  such as a thermal pad, a thermal tape, and a thermal paste, and a heat sink  5  is placed on the heat cooler  100  using a heat conductive adhesive  2   a.    
         [0079]    The heat cooler  100  may extend from the heat-generating device  1 , and an auxiliary heat sink  5   a  may be disposed on the extending portion of the heat cooler  100 , so as to dissipate heat from the heat-generating device  1  more rapidly. 
         [0080]    In the above-described structure, heat generated from the heat-generating device  1  is transferred to the heat cooler  100  having a predetermined size. Then, the distilled water  25  filled in the bores  22  are evaporated by the heat and are moved upward through the gaps between the heat conductive beads  24  formed of, for example, copper by the capillary phenomenon. Along with this, heat is dissipated to an outside area through the body  20 . 
         [0081]    Thereafter, if the body  20  is cooled, vapor condenses back to the distilled water  25 , and the condensed distilled water  25  moves rapidly down to the lower sides of the bores  22  through the gaps between the copper beads  24 . Then, the distilled water  25  is evaporated again by heat from the heat-generating device  1 . That is, the heat cooler  100  functions as a heat sink having high heat conductivity because heat is conducted to an outside area through the copper beads  24  and the body  20  of the heat cooler  100 . In addition, the heat cooler  100  functions as a heat pipe having good heat diffusion characteristics because heat is diffused as the distilled water  25  filled in the bores  22  is rapidly circulated between the lower and upper sides of the bores  22  while being evaporated and condensed. 
         [0082]    Some of heat generated from the heat-generating device  1  is transferred to the heat conductive beads  24  having high heat conductivity. That is, since the heat conductive beads  24  function as a heat absorber, the effective heat-transfer volume of the heat cooler  100  is increased so that heat generated from the heat-generating device  1  can be rapidly transferred to cool the heat-generating device  1 . 
         [0083]    Therefore, owing to the heat conductive beads  24  filled in the bores  22 , the heat conduction rate of the heat cooler  100  can be greater than that of a related-art heat sink, and the heat diffusion rate of the heat cooler  100  can be greater than that of a related-art heat pipe. 
         [0084]    In other words, owing to the heat conductive beads  24  filled in the bores  22 , the heat diffusion and conduction rates of the heat cooler  100  can be higher than those of a related-art heat cooler having the same size. 
         [0085]    In addition, since the vacuum spaces  26  are formed in the bores  22 , the distilled water  25  filled in the bores  22  can be evaporated at a relatively low temperature owing to the vacuum conditions and evaporation spaces provided by the vacuum spaces  26 . Therefore, the heat conduction and diffusion rates of the heat cooler  100  can be improved. 
         [0086]      FIG. 7  is a view illustrating another application example of the heat cooler  100  of  FIG. 1 . 
         [0087]    Referring to  FIG. 1 , since the bores  22  have the same height and are sealed as independent regions, the heat diffusion rate of the heat cooler  100  may be relative low in a lateral direction. 
         [0088]    Referring to  FIG. 7 , the height of some of the bores  22  is adjusted so that a gap can be formed between some of the bores  22  and the metal foil  10 . Therefore, a liquid or gas refrigerant can flow horizontally between neighboring bores  22  through the gap. 
         [0089]    In this case, the heat diffusion rate of the heat cooler  100  can be increased; however, it may be difficult to make the heat cooler  100 , and the heat diffusion and conduction rates of the heat cooler  100  may be varied according to the installation position of the heat cooler  100 . 
         [0090]      FIGS. 8 and 9  illustrate a heat cooler  130  according to another embodiment of the present invention. 
         [0091]    In the current embodiment, a body  131  is bonded to a metal foil  132  using a heat conductive adhesive  134 . 
         [0092]    A plurality of hollow protrusions  136  are formed in one piece with the body  131 , and heat conductive beads  137  are filled in the hollow protrusions  136 . Distilled water  138  is filled between the heat conductive beads  137  as a liquid refrigerant. 
         [0093]    The body  131  may be formed of a metal plate having a thickness in the range from 0.08 mm to 0.3 mm, and the hollow protrusions  136  may be formed through a deep drawing process. However, the present invention is not limited thereto. For example, the body  131  may be formed of metal or carbon through a molding process. 
         [0094]    The hollow protrusions  136  may have a height in the range from 1 mm to 20 mm, and vacuum spaces  135  may be formed in the hollow protrusions  136 . 
         [0095]    In the current embodiment, heat is transferred to the body  131  through the metal foil  132 . In the hollow protrusions  136  of the body  131 , heat is diffused as the distilled water  138  is evaporated by the heat and is moved upward through gaps between the heat conductive beads  137 . Along with this, the heat is dissipated to the outside of the hollow protrusions  136 . 
         [0096]    Both the edge of the body  131  and the edge of the metal foil  132  are coated with a metal plate layer  133  to prevent leakage of the distilled water  138  from the hollow protrusions  136 . In addition, heat can be transferred from the metal foil  132  to the body  131  through the metal plate layer  133 . 
         [0097]    As compared with a related-art heat sink, the heat cooler  130  of the current embodiment is lighter and can be fabricated more easily. In addition, the heat diffusion rate of the heat cooler  130  is high. 
         [0098]    Furthermore, since the heat cooler  130  has a large surface area owing to the hollow protrusions  136 , the cooling ability of the heat cooler  130  can be improved. 
         [0099]    In addition, since the height of the heat cooler  130  is varied owing to the hollow protrusions  136 , air may swirl around the heat cooler  130  to cause convection, and thus the cooling ability of the heat cooler  130  may be improved. 
         [0100]      FIG. 10  is a cutaway view illustrating a heat cooler  200  according to another embodiment of the present invention. 
         [0101]    According to the current embodiment, a bore  214  is formed in a length direction of a metal pipe body  210  of the heat cooler  200 . Grooves  212  are formed on an inner surface of the bore  214  in a length direction of the metal pipe body  210  and arranged in a circumferential direction of the metal pipe body  210 , or a wick  240  formed of a braided wire is disposed in the bore  214 . In addition, heat conductive beads  220  are filled in the bore  214  of the metal pipe body  210 , and a refrigerant  230  is filled between the heat conductive beads  220 , so as to improve the cooling efficiency of the heat cooler  200 . 
         [0102]    Alternatively, both the grooves  212  and the wick  240  may be provided in the metal pipe body  210 . In addition, like in the above-described embodiments, vacuum spaces may be formed in the bore  214  to facilitate circulation of the refrigerant  230 . 
         [0103]    Both ends of the heat cooler  200  are sealed with metal caps  250  by using a heat conductive adhesive or through a soldering or welding process. 
         [0104]    The heat cooler  200  has a long shape. 
         [0105]    In the current embodiment, the heat cooler  200  includes the metal pipe body  210 . However, the present invention is not limited thereto. For example, the heat cooler  200  may include a plate-shaped metal body instead of the metal pipe body  210 . 
         [0106]      FIG. 11  is a cutaway view illustrating a heat cooler  300  according to another embodiment of the present invention. 
         [0107]    According to the current embodiment, a plurality of penetration holes  314  are formed in a length direction of a body  310 , heat conductive beads  320  are filled in the penetration holes  314 , and a refrigerant  330  is filled between the heat conductive beads  320 . 
         [0108]    Like in the above-described embodiments, vacuum spaces may be formed in the penetration holes  314  to facilitate circulation of the refrigerant  330 . 
         [0109]    Both ends of the heat cooler  300  are sealed with metal caps  350  by using a heat conductive adhesive or through a soldering or welding process. 
         [0110]    As described above, according to the present invention, the heat diffusion and conduction rates of the heat cooler can be high as compared with a related-art heat sink. In addition, the heat diffusion and conduction rates of the heat cooler can be adjusted. 
         [0111]    In addition, the internal surfaces of a metal pipe can be increased to facilitate circulation of a refrigerant by the capillary phenomenon. Therefore, the heat diffusion and conduction rates can be increased. 
         [0112]    In addition, heat generated from a heat-generating device can be diffused and dissipated more efficiently by using the latent heat and specific heat of heat conductive beads. 
         [0113]    In addition, both heat diffusion and conduction can be rapid on the scale of micrometers. 
         [0114]    In addition, the heat cooler of the present invention can be easily fabricated in a small size. 
         [0115]    In addition, the heat cooler of the present invention can be easily adapted to application environments for efficient cooling. 
         [0116]    In addition, according to the present invention, the heat diffusion and conduction rates of the heat cooler can be substantially uniform regardless the installation of the heat cooler. 
         [0117]    While the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.