Abstract:
A heat-dissipating device includes: a planar body made of a graphite laminate and extending along an x-y plane of the graphite laminate; and a plating metal layer formed on the planar body. The heat-dissipating device further includes a metal panel. The planar body is connected substantially perpendicularly to the metal panel. A method of making the heat-dissipating device is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of Taiwanese application No. 098109727, filed on Mar. 25, 2009. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a heat-dissipating device, more particularly to a heat-dissipating device including a plating metal layer formed on a graphite laminate. 
         [0004]    2. Description of the Related Art 
         [0005]    A heat-dissipating device made from metal having a high conductivity, such as copper or aluminum, is usually used for dissipating heat generated in electronic components into ambient air. When the operating speed of the electronic components is faster, a rate of heat generation is increased. Therefore, a large heat-dissipating area of the heat-dissipating device is required so as to quickly dissipate heat. However, such requirement increases a weight of the heat-dissipating device. 
         [0006]    Compared to copper or aluminum, graphite has advantages such as low heat resistance, light weight, and high conductive coefficient. However, since graphite has insufficient rigidity and is frangible, graphite is likely to be damaged and to be deformed due to impact or stress during use. In addition, since graphite cannot bond directly to metal or alloy by welding, graphite itself is not used as the heat-dissipating device. 
         [0007]    An existing method of making a heat-dissipating device is generally carried out by adhering a metal layer to graphite for improving rigidity and strength thereof. Subsequently, electronic components are connected to the graphite by adhering to the metal layer. However, the metal layer is likely to separate from the graphite, and heat conduction can be discontinuous due to the adhesive between the metal layer and the graphite, which reduces heat conduction efficiency. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, an object of the present invention is to provide a heat-dissipating device that can overcome the aforesaid drawbacks associated with the prior art. 
         [0009]    Another object of this invention is to provide a method of making the heat-dissipating device. 
         [0010]    According to one aspect of the present invention, a heat-dissipating device comprises: a planar body made of a graphite laminate and extending along an x-y plane of the graphite laminate; and a plating metal layer formed on the planar body. 
         [0011]    According to another aspect of the present invention, a method of making the heat-dissipating device comprises: (a) cleaning a planar body that is made of a graphite laminate and that extends along an x-y plane of the graphite laminate; and (b) electroplating the planar body so that a plating metal layer is formed on the planar body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which: 
           [0013]      FIG. 1  is a perspective view of the first preferred embodiment of a heat-dissipating device according to this invention; 
           [0014]      FIG. 2  is a flowchart illustrating the first preferred embodiment of a method for making the heat-dissipating device according to this invention; 
           [0015]      FIG. 3  is a perspective view of the second preferred embodiment of the heat-dissipating device according to this invention; 
           [0016]      FIG. 4  is a perspective view of the third preferred embodiment of the heat-dissipating device according to this invention; 
           [0017]      FIG. 5  is a perspective view of the fourth preferred embodiment of the heat-dissipating device according to this invention; 
           [0018]      FIG. 6  is a perspective view of the fifth preferred embodiment of the heat-dissipating device according to this invention; and 
           [0019]      FIG. 7  is a perspective view of the sixth preferred embodiment of the heat-dissipating device according to this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. 
         [0021]    Referring to  FIG. 1 , the first preferred embodiment of a heat-dissipating device  2  according to this invention includes a planar body  21  and a plating metal layer  22 . 
         [0022]    The planar body  21  is made of a graphite laminate and extends along an x-y plane of the graphite laminate. Compared to metal, such as copper or aluminum, graphite has low heat resistance, light weight, and high conductive coefficient. In addition, graphite has excellent conduction of heat in the x-y plane and insulation against heat in the direction (Z) perpendicular to the x-y plane. 
         [0023]    The plating metal layer  22  is formed on the planar body  21  through electroplating. By forming the plating metal layer  22 , an electronic component  100 , depending on actual requirements, can be mounted on the plating metal layer  22  of the heat-dissipating device  2  through welding or adhesion. Since electroplating is to form a dense metal film through film nucleation and growth, when the plating metal layer  22  is electroplated on the planar body  21 , the plating metal layer  22  can be tightly attached to the planar body  21 , thereby conducting heat generated from the electronic component  100  to ambient air along the x-y plane of the graphite laminate of the planar body  21 . 
         [0024]    In this embodiment, the planar body  21  has top and bottom surfaces  210 ,  211  which extend parallel to the x-y plane, and a pair of opposite first lateral sides  212  (only one is shown) and opposite second lateral sides  213  (only one is shown), which interconnect the top and bottom surfaces  210 ,  211 . The plating metal layer  22  is formed on the top surface  210  and the opposite first lateral sides  212 . 
         [0025]    The plating metal layer  22  is selected from the group consisting of copper, nickel, chromium, gold, silver, tin, platinum, and combinations thereof, which have high heat conductivity. Due to high heat conductivity, heat dissipation efficiency is not reduced by forming the plating metal layer  22  on the planar body  21 , but is actually increased. The heat-dissipating device  2  can increase the heat dissipation efficiency up to 10%-15% compared to a heat-dissipating device including merely graphite laminate. In addition, due to the presence of the plating metal layer  22 , the planar body  21  is provided with increased surface hardness and rigidity. 
         [0026]    Referring to  FIG. 2 , a method of making the heat-dissipating device  2  includes steps  11  and  12 . 
         [0027]    In step  11 , the planar body  21  is cleaned so as to remove oil contaminant and oxide thereon. 
         [0028]    Preferably, the cleaning is conducted by using acid solution. Alternatively, the cleaning can be conducted by using atmospheric pressure plasma. In this embodiment, the planar body  21  is immersed for 50 sec in a solution including sulfuric acid having a concentration of not less than 0.5 wt %, such as a concentration of 10 wt %, and a surfactant so as to remove contaminant on the surface of the planar body  21 . After washing with water, the planar body  21  is immersed in sulfuric acid having a concentration of 3-5 wt % for 30 sec so as to enhance effect on removal of oil contaminant and oxide. 
         [0029]    In step  12 , the planar body  21  is electroplated so that the plating metal layer  22  is formed on the planar body  21  so as to obtain the heat-dissipating device  2 . the plating metal layer  22  preferably has a layer thickness not less than 1 μm. 
         [0030]    Referring to  FIG. 3 , the second preferred embodiment of the present invention differs from the first preferred embodiment in that the plating metal layer  22  is further formed on the bottom surface  211 , which can prevent graphite dust from contaminating other components and improve the heat dissipation efficiency of the heat-dissipating device  2 . The electronic component  100  can be disposed on any surface of the planar body  21 . 
         [0031]    Referring to  FIG. 4 , the third preferred embodiment of the present invention differs from the second preferred embodiment in that the plating metal layer  22  includes a plurality of different metal or alloy films. In this embodiment, the plating metal layer  22  includes two metal films wherein a copper film  221  having a thickness ranging from 8 μm to 10 μm is formed on the planar body  21 , and a nickel film  222  having a thickness ranging from 2 μm to 5 μm is formed on the copper film  221 . The total thickness of the plating metal layer  22  is not less than 1 μm for preventing the plating metal layer  22  from separating from the planar body  21  and for avoiding insufficiency of structural strength. 
         [0032]    Referring to  FIG. 5 , the fourth preferred embodiment of the present invention differs from the second preferred embodiment in that the heat-dissipating device  2  further includes a heat conductive adhesive  25  disposed between the electronic component  100  and the heat-dissipating device  2  so as to assist in heat removal. 
         [0033]    Referring to  FIG. 6 , the fifth preferred embodiment of the present invention differs from the fourth preferred embodiment in that the heat-dissipation device  2  further includes an insulation film  23  attached to the plating metal layer  22  for electrical insulation between the electronic component  100  and the heat-dissipation device  2 . In this embodiment, the insulation film  23  is made from polyethylene terephthalate (PET), and the electronic component  100  which needs to be electrically insulated is mounted on the insulation film  23  through the heat conductive adhesive  25 . 
         [0034]    Referring to  FIG. 7 , the sixth preferred embodiment of the present invention includes a metal panel  24  and a plurality of the planar bodies  21 . Each of the planar bodies  21  is formed with the plating metal layer  22 . The metal panel  24  has a first surface  241  adapted to support and contact the electronic component  100  and an opposite second surface  242  provided with a plurality of parallel elongated grooves  243 . 
         [0035]    The planar bodies  21  are substantially perpendicular to the second surface  242 . One of the first lateral sides  212  of each planar body  21  is inserted into a respective one of the elongated grooves  243 . A portion of the plating metal layer  22  covering the inserted first lateral side  212  of each planar body  21  is secured to the metal panel  24  by welding or adhesive bonding. In use, the heat generated by the electronic component  100  is transferred to the metal panel  24  and is dissipated through the planar bodies  21 . 
         [0036]    With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.