Abstract:
A heat dissipation device is provided for dissipating heat generated by electronic components mounted on a printed circuit board in an electronic system. The electronic components have different heights. The heat dissipation device includes a connecting plate, at least two elastic members mounted on the connecting plate, and a heat sink having a substrate mounted on the connecting plate and located above one of the electronic components. A number of joining members extend through the printed circuit board and engage with the substrate to attach the substrate on the one electronic component on the printed circuit board. A distance between the substrate and the connecting plate is adjustable by adjusting the joining members to make the substrate intimately contact the one electronic component.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to an electronic system with a heat dissipation device thermally contacting a plurality of electronic components having different heights, to dissipate heat of the electronic components simultaneously. 
         [0003]    2. Description of Related Art 
         [0004]    Generally, a heat dissipation device thermally contacts electronic components mounted on a printed circuit board (PCB) to dissipate heat of the electronic components. The heat dissipation device comprises a base contacting the electronic components, and a plurality of fins extending upwardly from a top surface of the base. When the electronic components have different heights, the base of the heat dissipation device is not able to intimately contact all of the electronic components. As a result, a large thermal barrier exists between some of the electronic components and the base, which adversely affects the heat dissipation for such electronic components. 
         [0005]    What is needed, therefore, is a heat dissipation device which can effectively dissipate heat generated by electronic components on a printed circuit board when the electronic components have different heights. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an assembled view of a heat dissipation device in accordance with an embodiment of the present disclosure, and a printed circuit board below the heat dissipation device. 
           [0007]      FIG. 2  is an inverted view of the heat dissipation device and printed circuit board of  FIG. 1 . 
           [0008]      FIG. 3  is a partly exploded view of the heat dissipation device of  FIG. 1 . 
           [0009]      FIG. 4  is an inverted view of the heat dissipation device of  FIG. 3 . 
           [0010]      FIG. 5  is a side view of the heat dissipation device of  FIG. 1 , before a first heat sink of the heat dissipation device is attached to a connecting plate of the heat dissipation device. 
           [0011]      FIG. 6  is similar to  FIG. 1 , but showing the first heat sink attached to the connecting plate. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  illustrates a heat dissipation device in accordance with an embodiment of the present disclosure. The heat dissipation device thermally contacts a first electronic component  200  and a second electronic component  300  mounted on a printed circuit board (PCB)  100  of an electronic device (not shown), to dissipate heat generated by the first and second electronic components  200 ,  300 . In this exemplary embodiment, the electronic device is a game player; the first electronic component  200  is a central processing unit (CPU), and the second electronic component  300  is a graphic processing unit (GPU). 
         [0013]    The heat dissipation device comprises a connecting plate  90 , a first heat sink  10 , a second heat sink  20 , and a third heat sink  30 . The first, second and third heat sinks  10 ,  20 ,  30  are engaged on the connecting plate  90 . The first heat sink  10  thermally contacts the first electronic component  200 . The second heat sink  20  thermally contacts the second electronic component  300 . A heat pipe  50  thermally connects the second heat sink  20  and the third heat sink  30 . In this embodiment, the connecting plate  90  electrically connects with an enclosure of the electronic device. 
         [0014]    Referring also to  FIGS. 2-4 , the connecting plate  90  is made of material having good thermal conductivity and electrical conductivity, and has a rectangular configuration. In this embodiment, the connecting plate  90  is a bottom fan cover for cooperation with a top fan cover (not shown) to guide airflow flowing to the heat sinks  10 ,  20 ,  30 . A first end of the connecting plate  90  defines an approximately semicircular first opening  94  corresponding to a fan (not shown) which sucks airflow through the first opening  94  and blows airflow toward the heat sinks  10 ,  20 ,  30 . A baffle  95  extends downwardly from an edge of the first opening  94  near the first heat sink  10 . A second end opposite to the first end defines a rectangular second opening  91  to receive the first heat sink  10 , and two pairs of through holes  92  at two opposite sides of the second opening  91 . 
         [0015]    The first heat sink  10  is an aluminum extrusion type heat sink, and has good thermal conductivity and electrical conductivity. The first heat sink  10  comprises a substrate  11  and a plurality of plate fins  12  integrally extending therefrom. The substrate  11  has a rectangular configuration, and defines two screw holes  110  at two diagonally opposite ends thereof. The plate fins  12  are parallel to each other to define a plurality of channels. When a fan is installed, ends of the channels face toward the fan, and airflow is for guided through the channels. Two engaging portions  18  extend outwardly from two opposite outermost plate fins  12  of the first heat sink  10 , respectively. Each of the engaging portions  18  has an inclined outer surface (not labeled). A root  17  of each outermost plate fins  12  and a corresponding engaging portion  18  define an undercut  180 . A distance between the two outermost plate fins  12  is slightly less than a width of the rectangular opening  91 . The substrate  11  is larger than the rectangular opening  91 ; thus, the substrate  11  can abut a bottom surface of the connecting plate  90  when the first heat sink  10  is assembled to the connecting plate  90  to limit upright movement of the first heat sink  10 . 
         [0016]    The second heat sink  20  comprises a base  21  mounted at the bottom surface of the connecting plate  90 , and a heat radiator  22  mounted on the connecting plate  90  and corresponding to the base  21 . The heat radiator  22  is integrally made by aluminum extrusion. The second heat sink  20  is located at a middle portion of the connecting plate  90 , between the first opening  94  and the second opening  91 . The base  21  has a rectangular configuration and is made of material having good thermal conductivity. The base  21  has a lateral portion corresponding to the heat radiator  22  and another lateral portion defining a long groove  210  at a top thereof. The base  21  defines two screw holes  211  at two diagonally opposite ends thereof. The base  21  has two tabs  212  extending from near the screw holes  211  for orienting the base  21  to the connecting plate  90 . 
         [0017]    The third heat sink  30  is an aluminum extrusion type heat sink. The third heat sink  30  is mounted on the connecting plate  90  and located near the first and second heat sinks  10 ,  20 . The heat pipe  50  is L-shaped and flattened. The heat pipe  50  comprises an evaporating section  51  received in the groove  210  of the base  21  of the second heat sink  20 , and a condensing section  52  connecting with the evaporating section  51 . The condensing section  52  thermally contacts the bottom surface of the connecting plate  90 , to transfer heat to the connecting plate  90  and the second heat sink  20 . A thermal cover  60  is mounted on the condensing section  52  of the heat pipe  50 . The thermal cover  60  is made from a metal plate having good thermal conductivity. The thermal cover  60  has a generally omega-shaped (Ω-shaped) cross-section. A middle portion of the thermal cover  60  is protrudes downwardly to define a generally concave groove  61 . An outer surface of the condensing section  52  of the heat pipe  50  can intimately contact the thermal cover  60  in the groove  61 . Two lateral portions of the thermal cover  60  are attached to the bottom surface of the connecting plate  90 , to transfer heat from the heat pipe  50  to the connecting plate  90 . In addition, the thermal cover  60  can protect the heat pipe  50  from damage. 
         [0018]    The elastic members  40  are mounted on the connecting plate  90  at two opposite sides of the second opening  91 , to contact and support the first heat sink  10 . Each elastic member  40  is made of sheet material having good electrical conductivity, and has a J-shaped configuration. Each elastic member  40  has a flat mounting portion  41  mounted on the connecting plate  90 , an elastic middle portion  42 , and an engaging portion  43 . The mounting portion  41  defines two through holes  410  corresponding to the through holes  92 . A plurality of fasteners, such as rivets  80 , engage in the through holes  92 ,  410  to mount the elastic members  40  to the connecting plate  90 . The middle portions  42  of the elastic members  40  intimately contact the roots  17  of the outermost plate fins  12  of the first heat sink  10 . 
         [0019]    Referring also to  FIGS. 5-6 , the elastic members  40  are mounted at two opposite sides of the second opening  91  and face each other. The elastic middle portions  42  of the elastic members  40  incline toward the second opening  91 . An inner distance W 1  between the middle portions  42  of the elastic members  40  is less than an outer distance W 2  between the roots  17  of the outermost plate fins  12 . A height H 1  of each elastic member  40  is less than a height H 2  of each root  17 . In assembly, when the first heat sink  10  begins to extend through the rectangular opening  91  of the connecting plate  90  from bottom to top, the elastic members  40  are pushed outwardly by the engaging portions  18  of the first heat sink  10 . When the engaging portions  18  of the first heat sink  10  extend beyond tops of the elastic members  40 , elastic forces afforded by the elastic members  40  make the elastic members  40  sandwich the first heat sink  10  and thereby mount the first heat sink  10  on the connecting plate  90 . Since the distance W 1  between the middle portions  42  is less than the distance W 2  between the roots  17 , the middle portions  42  of the elastic members  40  elastically abut against the roots  17  of the outermost plate fins  12 . Since the height H 1  of each elastic member  40  is less than a height H 2  of each root  17 , a gap h is defined between a top surface of the substrate  11  of the first heat sink  10  and the bottom surface of the connecting plate  90 . Thus, a height of the substrate  11  relative to the connecting plate  90  is adjustable (see below), so that the substrate  11  can have good thermal contact with the first electronic component  200  of the PCB  100 . In this state, the elastic members  40  always firmly contact the first heat sink  10 , thereby maintaining electrical connection between the connecting plate  90  and the first heat sink  10 . 
         [0020]    After the second heat sink  20  is assembled on the PCB  100 , the first heat sink  10  is assembled on the PCB  100  to thermally contact the first electronic component  200  of the PCB  100 . Two joining members such as screws  70  extend through the PCB  100  and engage in the screw holes  110  of the substrate  11  to fix the first heat sink  10  on the PCB  100 . When the first and second electronic components  200 ,  300  have different heights, a distance between the substrate  11  and the first electronic component  200  is adjustable by tightening or loosening the screws  70 . The elastic members  40  retain the first heat sink  10  on the connecting plate  90  and enable the first heat sink  10  to move in a range corresponding to the gap h. The elastic members  40  intimately contact the roots  17  of the first heat sink  10  at whatever height the first heat sink  10  is adjusted to, thereby electrically connecting the connecting plate  90  with the first heat sink  10  to remove static electricity from the first and second electronic components  200 ,  300 . 
         [0021]    It is to be understood, however, that even though numerous characteristics and advantages of embodiments have been set forth 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.