Abstract:
A method for manufacturing a heat spreader includes steps of: providing an elongated and flat sectional material with a through hole defined therein; cutting the sectional material into a plurality of parts each in a predetermined length to form a plurality of casings, wherein each of the casings defines a vapor chamber therein and has at least an opening in a side thereof; forming a wick structure on an inner face of the casing; providing a plurality of supporting members; placing and fixing the supporting members into the vapor chamber of the casing; and injecting working liquid into the vapor chamber and sealing the casing.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The disclosure generally relates to heat spreaders and, more particularly, to a heat spreader with a vapor chamber having a plurality of supporting members received in the vapor chamber and a method for manufacturing the heat spreader. 
         [0003]    2. Description of Related Art 
         [0004]    Electronic components, such as central processing units (CPUs) comprise numerous circuits operating at high speeds and generating substantial heat. Under most circumstances, it is necessary to cool the CPUs to maintain safe operating conditions and assure that the CPUs function properly and reliably. In the past, various approaches have been used to cool electronic components. 
         [0005]    A heat spreader with a vapor chamber is usually used to help heat dissipation for electronic components. The heat spreader generally includes a base, a cover mounted on the base and a sealed chamber defined between the base and the cover. Moderate working liquid is contained in the chamber. The base has a wick structure spreading on a whole inner face thereof, and the cover has a wick structure spreading on a whole inner face thereof, too. During operation, the base absorbs heat from an electronic component, and the working liquid is heated into vapor in the chamber. The vapor flows towards the cover and dissipates the heat to the cover, then condenses into liquid and returns back to the base by capillary force generated by the wick structures to continue a next phase-change cycle. 
         [0006]    However, since the heat spreader is a hollow plate-shaped structure, it is prone to be deformed when subjected to a large pressure. Such deformation of the heat spreader may result in the wick structures disengaged from the inner faces of the heat spreader, thus adversely affecting heat transfer efficiency of the heat spreader. 
         [0007]    What is needed, therefore, is a heat spreader with a vapor chamber which can overcome the above problems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0009]      FIG. 1  is an assembled, isometric view of a heat spreader in accordance with a first embodiment of the disclosure, with a heat sink positioned thereon and an electronic component positioned therebelow. 
           [0010]      FIG. 2  is a cross-sectional view of  FIG. 1 , taken along a line II-II thereof. 
           [0011]      FIG. 3  is an assembled, isometric view of a heat spreader in accordance with a second embodiment of the disclosure, with a heat sink positioned thereon and an electronic component positioned therebelow. 
           [0012]      FIG. 4  is a cross-sectional view of  FIG. 3 , taken along a line IV-IV thereof. 
           [0013]      FIG. 5  is a schematic view showing a manufacturing process of a casing of the heat spreader of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIGS. 1-2 , a heat spreader  10  in accordance with a first embodiment of the disclosure absorbs heat generated by an electronic component  20  mounted below the heat spreader  10 . Typically, a finned metal heat sink  30  is attached to a top face of the heat spreader  10  to remove the heat therefrom. The heat absorbed by the heat sink  30  is then dissipated to ambient air. 
         [0015]    The heat spreader  10  comprises a hollow casing  11  which defines a vapor chamber  12  therein, a wick structure  13  formed on an inner face of the casing  11 , and a plurality of supporting members  14  received in the vapor chamber  12 . A predetermined quantity of working liquid, such as water, alcohol, olefin and so on, is contained in the vapor chamber  12  for transferring heat by phase change. The vapor chamber  12  is evacuated for facilitating evaporation of the working liquid. 
         [0016]    The casing  11  is a hollow rectangular plate and integrally made of a metal with good heat conductivity, such as aluminum, copper, or an alloy thereof. The casing  11  comprises a base  15  thermally attached to the electronic component  20 , a cover  16  located above and parallel to the base  15  and a sidewall (not labeled) interconnecting the base  15  and the cover  16 . As best seen in  FIG. 2 , the sidewall has two opposite lateral sides each of which has a curved profile protruding outwardly. The heat sink  30  is thermally disposed on the cover  16 . 
         [0017]    The wick structure  13  spreads on the whole inner face of the casing  11  and surrounds the vapor chamber  12 . The wick structure  13  can be selected from some suitable materials, such as sintered metal powder, metal mesh, carbon nanotube array, bundle of fibers and so on. 
         [0018]    The supporting members  14  each are integrally made of a metal with good heat conductivity, such as aluminum, copper, or an alloy thereof. Each of the supporting members  14  has a column configuration. The supporting members  14  are sandwiched between the base  15  and the cover  16  of the casing  11 . An axis of each supporting member  14  is perpendicular to the base  15  and the cover  16  of the casing  11 . Opposite bottom and top ends of each supporting member  14  are attached to the wick structure  13  formed on the base  15  and the cover  16 , respectively. The supporting members  14  are evenly arranged in the vapor chamber  12  and spaced from each other. 
         [0019]    Referring to  FIGS. 3-4  also, a heat spreader  10   a  of a second embodiment of the disclosure is similar to that of the previous embodiment, excepting a casing  11   a  and a plurality of supporting members  14   a  received in the casing  11   a.  The differences between the two embodiments are that two opposite lateral sides of the sidewall of the casing  11   a  are planar and perpendicular to the base  15  of the casing  11   a,  whereby the casing  11   a  has a rectangular parallelepiped profile, and each of the supporting members  14   a  has a column-spiral configuration similar to a helical spring. An axis of each supporting member  14   a  is perpendicular to the base  15  and the cover  16  of the casing  11   a . Opposite bottom and top ends of each supporting member  14   a  are attached to the wick structure  13  formed on the base  15  and the cover  16 , respectively. 
         [0020]    Referring to  FIG. 5  also, a method for manufacturing the heat spreader  10 ,  10   a  of the disclosure comprises steps described below. Firstly, a metallic elongated and flat tube is provided. The tube is then cut into a plurality of similar semifinished parts each having a predetermined length in order to form the casing  11 ,  11   a,  wherein each semifinished part has two openings at two opposite sides thereof. An insert (not shown) is inserted into the semifinished part through one of the openings thereof, with a gap defined between the insert and top and bottom of the semifinished part. Metal powder is then filled into the gap between the insert and the semifinished part and then sintered onto the inner face of the semifinished part by heating the metal powder, to thereby form the wick structure  13  over the inner face of the semifinished part. The insert according to the preferred embodiment is a solid metallic block which is withdrawn from the semifinished part after the powder is sintered onto the inner face of the semifinished part. Alternatively, the insert can be a hollow block formed by woven meshes which is able to be sintered onto the inner face of the semifinished part as a part of the wick structure  13  when sintering the powder. Thereafter, the supporting members  14 ,  14   a  are placed into the semifinished part, and the supporting members  14 ,  14   a  are fixed on the wick structure  13  formed in the semifinished part by sintering or soldering. Finally, two opposite opening ends of the semifinished part are punched to be sealed for sealing the vapor chamber  12 , in which an injection hole is formed in one of the two sealed opposite sides so that work liquid can be injected into the vapor chamber  12  via the injection hole and the vapor chamber can be vacuumed via the injection hole. Finally, the injection hole is sealed, whereby the casing  11 ,  11   a,  is formed by the semifinished part and the manufacturing of the heat spreader  10  is finished, which incorporates the supporting members  14 ,  14   a  therein. 
         [0021]    During use of the heat spreader  10 , the electronic component  20  is attached to the base  15 , and the base  15  absorbs the heat produced by the electronic component  20 . The working liquid saturated in the wick structure  13  formed on the base  15  is heated into vapor. The vapor is quickly diffused into the whole vapor chamber  12  of the heat spreader  10 . When the vapor contacts the wick structure  13  formed on the cover  16  and the cover  16 , it gives out heat and condenses into liquid. The condensed working liquid then flows back to the base  15  through the wick structure  13 . The supporting members  14 ,  14   a  which are received in the vapor chamber  12  prevent the casing  11 ,  11   a,  from being deformed when the casing  11 ,  11   a,  is subject to pressure acting thereon. Additionally, since the casing  11 ,  11   a  is likely to expand when subject to heat, the spring-like supporting members  14   a  of the second embodiment could pull the base  15  and the cover  16  together by resilient force, to thereby limit the casing  11   a  to deform within a reasonable scale. 
         [0022]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set fourth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.