Abstract:
An electronic device includes an electronic component and a heat dissipating casing configured to dissipate heat from the electronic component. The casing includes top and bottom sides of the heat dissipating casing forming a sealed chamber, and a pore structure formed within the sealed chamber. The sealed chamber is configured to receive a working medium and the pore structure is configured to absorb at least a portion of the working medium, whereby the heat generated from the electronic component is dissipated by a phase change of the working medium.

Description:
FIELD 
     The subject matter herein generally relates to a heat dissipation, and especially to a heat dissipation casing used in an electronic device. 
     BACKGROUND 
     During the operation of an electric products (computers, notebooks or touch pads), chips, such as CPU, GPU produces heat. Heat has to be quickly carried away from the chips during the operation. Excessively high temperature causes the chips unable to work normally. Various cooling means, such as cooling system, have been developed for dissipating heat from the chips of an electric product. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is a top plan view of an electronic device in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is a cross sectional view of the electronic device of  FIG. 1 , taken along line II-II thereof. 
         FIG. 3  is an enlarged view of a circle III shown in  FIG. 2 . 
         FIG. 4  is a top plan view of an electronic device in accordance with a second embodiment of the present disclosure. 
         FIG. 5  is a cross sectional view of the electronic device of  FIG. 4 , taken along line V-V thereof. 
         FIG. 6  is a cross sectional view of an electronic device in accordance with a third embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
     Referring to  FIGS. 1-3 , an electronic device  100  in accordance with a first embodiment of the present disclosure is shown. The electronic device  100  includes a heat dissipating casing  10 , and two electronic components  20 ,  30  thermally attached to the heat dissipating casing  10 . The heat dissipating casing  10  is capable of dissipating the heat generated from the electronic components  20 ,  30 . 
     The heat dissipating casing  10  includes a top plate  12 , a bottom plate  14 , a pore structure  16  and a working medium  18  located between the top plate  12  and the bottom plate  14 . 
     The top plate  12  and the bottom plate  14  can be made of metallic material with high heat conductivity, such as copper, aluminum, titanium or nickel. The top plate  12  is parallel to the bottom plate  14 . The top plate  12  is located at an inner side of the electronic device  100 , and the bottom plate  14  is located at an outer side of the electronic device  100 . Two opposite ends of each of the top plate  12  and the bottom plate  14  slant upwardly, and each has a cross section of circular arc shape. An outer edge of the top plate  12  is coupled to an outer edge of the bottom plate  14  by an annular connecting plate  13 . The pore structure  16  is sandwiched between the top plate  12  and the bottom plate  14  to support the top plate  12  and the bottom plate  14 . The top plate  12 , the connecting plate  13  and the bottom plate  14  cooperatively form a sealed chamber  101 , and the pore structure  16  and the working medium  18  are received in the sealed chamber  101 . The pore structure  16  is fixed on an inner face of the top plate  12 . The two electronic components  20 ,  30  are fixed on an outer face of the top plate  12 . 
     The pore structure  16  produces a capillary force for adsorbing the liquid working medium  18 , and has a porosity ranged from about 35% to about 65%. The working medium  18  may be water or alcohol. The pore structure  16  includes a main portion  162  adhered on the whole inner face of the top plate  12  and a plurality of convex portions  164  extending downwards from the main portion  162  and contacting the bottom plate  14 . Two opposite ends of the main portion  162  slant upwardly along the two opposite ends of each of the top plate  12  and the bottom plate  14 , and each has a cross section of circular arc shape. Each of the convex portions  164  is a long narrow strip. The convex portions  164  are parallel to and spaced from each other with an equal interval. A channel  165  is formed between every two adjacent convex portions  164  for flow of the working medium  18 . 
     In use, the temperature of the electronic device  100  rises due to the heat generated from the electronic components  20 ,  30 . Since the electronic components  20 ,  30  contact the top plate  12  of the heat dissipating casing  10  intimately. The heat is transmitted to the working medium  18  by the top plate  12 , so that the working medium  18  is heated and vaporized to flow downwards through the channels  165  of the pore structure  16  to the bottom plate  14 . The vaporized working medium  18  exchanges heat with the bottom plate  14  and then is condensed to liquid. The condensed working medium  18  then returns to the top plate  12  of the heat dissipating casing  10 . Therefore, the heat generated from the electronic components  20 ,  30  is dissipated continuously by above phase change cycle of the working medium  18 . The whole heat dissipating casing  10  has a heat transfer coefficient larger than 10000 W/(m 2 *K), about 30 times as much as that of the copper material. 
     Referring to  FIGS. 4-5 , an electronic device  100   a  in accordance with a second embodiment of the present disclosure is shown. The electronic device  100   a  includes a heat dissipating casing  10   a , and an electronic component  20   a  thermally attached to the heat dissipating casing  10   a . The heat dissipating casing  10   a  is capable of dissipating the heat generated from the electronic component  20   a.    
     The heat dissipating casing  10   a  includes a top plate  12   a , a bottom plate  14   a , a pore structure  16   a  and a working medium  18   a . The top plate  12   a  and the bottom plate  14   a  can be made of non-metallic material or metallic material with high heat conductivity, such as copper, aluminum, titanium or nickel. Two opposite ends of each of the top plate  12   a  and the bottom plate  14   a  slant upwardly, and each has a cross section of circular arc shape. An outer edge of the top plate  12   a  is coupled to an outer edge of the bottom plate  14   a  by an annular connecting plate  13   a.    
     The differences between the electronic device  100   a  of the second embodiment and the electronic device  100  of the first embodiment are in that: the heat dissipating casing  10   a  further includes a sealed, flat shell  15   a , in which a sealed chamber  101   a  is formed. The pore structure  16   a  and the working medium  18   a  are received in the sealed chamber  101   a  of the sealed shell  15   a . The electronic component  20   a  is thermally attached to the sealed shell  15   a.    
     The sealed shell  15   a  can be made of metallic material with high heat conductivity, such as copper, aluminum, titanium or nickel. Compared to aluminium magnesium alloy, the heat dissipating performance of the heat dissipating casing  10   a  increases more than 10 times. The sealed shell  15   a  is bent along a longitudinal direction thereof. Each of the top plate  12   a  and the bottom plate  14   a  defines a groove (not labeled), corresponding to the sealed shell  15   a . The sealed shell  15   a  is embedded in the grooves of the top plate  12   a  and the bottom plate  14   a . The sealed shell  15   a  is coupled with the top plate  12   a  and the bottom plate  14   a  by welding or molten way. A protrusion  152   a  protrudes from an outer face of one end of the sealed shell  15   a . The electronic component  20   a  is thermally attached to the protrusion  152   a  of the sealed shell  15   a . The other portion of the sealed shell  15   a  except for the protrusion  152   a  has a thickness equal to that of the heat dissipating casing  10   a . The pore structure  16   a  is fixed on an inner face of the sealed shell  15   a . The pore structure  16   a  includes a main portion  162   a  and a plurality of convex portions  164   a  extending downwards from the main portion  162   a . Each of the convex portions  164   a  is a long narrow strip. The convex portions  164   a  are parallel to and spaced from each other with an equal interval. A channel  165   a  is formed between every two adjacent convex portions  164   a  for flow of the working medium  18   a.    
     Referring to  FIG. 6 , an electronic device  100   b  in accordance with a third embodiment of the present disclosure is shown. The electronic device  100   b  includes a heat dissipating casing  10   b , and an electronic component  20   b  thermally attached to the heat dissipating casing  10   b . The heat dissipating casing  10   b  is capable of dissipating the heat generated from the electronic component  20   b.    
     The heat dissipating casing  10   b  is a sealed structure, and includes a top plate  12   b , a bottom plate  14   b , a pore structure  16   b  and a working medium  18   b  located between the top plate  12   b  and the bottom plate  14   b . An outer edge of the top plate  12   b  is coupled to an outer edge of the bottom plate  14   b  by an annular connecting plate  13   b . The top plate  12   b , the connecting plate  13   b  and the bottom plate  14   b  cooperatively form a sealed chamber  101   b , and the pore structure  16   b  and the working medium  18   b  are received in the sealed chamber  101   b . The two electronic component  20   b  is fixed on an outer face of the top plate  12   b.    
     The pore structure  16   b  includes a main portion  162   b  adhered on the whole inner face of the top plate  12   b  and a plurality of convex portions  164   b  extending downwards from the main portion  162   b  and contacting the bottom plate  14   b . A channel  165   b  is formed between every two adjacent convex portions  164   b  for flow of the working medium  18   b.    
     The differences between the electronic device  100   b  of the third embodiment and the electronic device  100  of the first embodiment are in that: the heat dissipating casing  10   b  further includes two heat insulating layers  17   b ,  19   b  and a cover  11   b.    
     In use, the temperature of a part of the electronic device  100   b  adjacent to the electronic component  20   b  rises rapidly due to the heat generated from the electronic component  20   b , while the other part of the electronic device  100   b  far from the electronic component  20   b  has a lower temperature. As a result, the heat in the outer face of the heat dissipating casing  10   b  returns back to an interior of the heat dissipating casing  10   b , and the temperature of the interior of the heat dissipating casing  10   b  rises continuously. To solve above problem, the heat insulating layer  17   b  is adhered on the top plate  12   b  of the heat dissipating casing  10   b  and surrounds the electronic component  20   b.    
     A user may contact a bottom of the heat dissipation casing  10   b , thus a position of the bottom plate  14   b  of the heat dissipation casing  10   b  where hands of the user may touch directly is covered by the heat insulating layer  19   b , thereby preventing the hands of the user feeling high temperature of the bottom of the heat dissipation casing  10   b.    
     The heat insulating layers  17   b ,  19   b  may be an insulating tape, a solidified gas gel layer, or a hollow film. 
     The cover  11   b  covers the top plate  12   b  and the bottom plate  14   b , the cover  11   b  and the top plate  12   b  cooperatively form a sealed room (not labeled) for receiving the electronic component  20   b  therein. 
     In the above embodiments, the electronic device  100 ,  100   a ,  100   b  may be notebook computer. 
     According to the present disclosure, since the heat dissipating casing  10 ,  10   a ,  10   b  defines a sealed chamber therein, and the working medium  18 ,  18   a ,  18   b  and the pore structure  16 ,  16   a ,  16   b  for absorbing the working medium  18 ,  18   a ,  18   b  are received in the chamber, thus the heat generated from the electronic components  20 ,  30 ,  20   a ,  20   b  is dissipated by the phase change cycle of the working medium  18 ,  18   a ,  18   b . Both the higher heat radiating efficiency and the demand for ultra-thin electronic products are obtained. 
     The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of an electronic device. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size and arrangement of the parts within the principles of the present disclosure up to, and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.