Patent Publication Number: US-2011061847-A1

Title: Heat dissipation device

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     This invention relates to a heat dissipation apparatus for dissipating heat generated by a chip, and more particularly to a heat dissipation apparatus which is made up of combination of a heat conductive plate and a heat-dissipating fin set. 
     2. Related Prior Art 
     A conventional approach to attaching a heat sink onto a chip has been to mount the whole heat sink on a carrier, which holds the chip, with the help of a fastener. A list of exemplary patents that describe some of these exemplary methods and apparatus are as follows: T.W. Pat. Nos. 286791, 311706, 571609, 437993 and M326763. Each of these patents discloses the usage of a wave-shaped fastener. However, none of the fasteners is used for fastening together a conductive plate and a heat-dissipating fin set to be a heat sink since the conductive plate and the heat-dissipating fin set are formed in one piece. 
     Another mechanism for heat dissipation apparatus is described in T.W. Pat. No. 501765 and includes a wave-shaped bar, a heat-dissipating fin set and a U-shaped holder. The wave-shaped bar, mounted across the U-shaped holder and the heat-dissipating fin set, is provided to prevent the heat-dissipating fin set from departing away from the U-shaped holder. Specifically, the wave-shaped bar is received in a through hole co-defined by the fins of the heat-dissipating fin set. It is understood that it must be quite difficult for the wave-shaped bar to be inserted into the through hole of the heat-dissipating fin set as well as the holes defined in the side walls of the U-shaped holder, which generally increases assembly complexity of the apparatus. 
     SUMMARY OF INVENTION 
     Broadly stated, the present invention is directed to a heat dissipation apparatus for dissipating heat generated by a chip. The heat dissipation apparatus mainly includes a heat conductive plate, a heat-dissipating fin set and a fastener. 
     Specifically, the heat-dissipating fin set has a bottom surface attached to a top surface of the heat conductive plate. The fastener includes a curled section and two legs joined to opposite ends of the curled section. The curled section is elastically deformable and is mounted across the heat-dissipating fin set. In addition, the curled section has at least one trough pressing against a top surface of the heat-dissipating fin set and at least one crest spaced apart from the top surface of the heat-dissipating fin set. Each of the legs of the fastener has a clasping member to be fastened on the heat conductive plate. When the clasping members of the legs are fastened on the heat conductive plate, the curled section is tightened by the legs. In such a manner, the heat dissipating fin set can be quickly mounted on the heat conductive plate without the need of soldering. 
     In another embodiment, a lining plate is included to be placed in between the curled section of the fastener and the heat-dissipating fin set. The lining plate is provided to help dispersing the force from the curled section to the heat-dissipating fin set, which simultaneously creates a close contact therebetween. 
     The advantages of the present invention will be understood more readily after a consideration of the drawings and the detailed description. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention is illustrated by the accompanying drawings in which corresponding parts are identified by the same numerals and in which: 
         FIG. 1  is a perspective view of a heat dissipation apparatus according to one embodiment; 
         FIG. 2  is a lateral cross-sectional view of the heat dissipation of  FIG. 1 ; 
         FIG. 3  is an exploded view of the heat dissipation of  FIG. 1 ; and 
         FIG. 4  is a longitudinal cross-sectional view of the heat dissipation of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring now to  FIGS. 1 through 4  of the drawings, this invention in accordance with one embodiment is directed to a heat dissipation apparatus for dissipating heat generated by a central processing unit (CPU). 
     As shown in  FIG. 1 , the heat dissipation apparatus includes a heat conductive plate  1 , a heat-dissipating fin set  2  placed on the heat conductive plate  1 , two liners  3  disposed on the heat-dissipating fin set  2 , two fasteners  4  received in the two liners  3 , and four fixing bolt units  5  secured at comers of the heat conductive plate  1 . In particular, each of the fasteners  4  has opposite ends fastened on the heat conductive plate  1  in order to press against the heat-dissipating fin set  2 . 
     As shown in  FIG. 2 , the heat dissipation apparatus is adopted to be mounted on a printed circuit board  6 , such as a computer motherboard, on which a chip carrier  60  is mounted. Upon the carrier  60  is a chip  61 , such as CPU. Note that it is the four fixing bolt units  5  to be used to quick mount the heat dissipation apparatus on the printed circuit board  6  rather than the fasteners  4 . Each of the fixing bolt units  5  includes a bolt  50  and a compression spring  51 . The bolt  50  has one end formed with a head  501  and the other end formed with a threaded portion  502 . The compression spring  51  is placed around the bolt  50  and between the head  501  of the bolt  50  and a top surface of the heat conductive plate  1 . The threaded portion  502  of the bolt  50  is mounted across a threaded hole defined in the printed circuit board  6  and screwed on a frame  9 . The heat conductive plate  1  has a bottom surface in close contact with the chip  61 . The heat-dissipating fin set  2  has a bottom surface in close contact with the top surface of the heat conductive plate  1 . Therefore, the heat generated within the chip  61  can be dissipated to the heat-dissipating fin set  2  via the heat conductive plate  1 . 
     The heat conductive plate  1  may be made of a single heat conductive material, such as copper, aluminum, ceramics, or the like. Alternatively, the heat conductive plate  1  may be made of complex materials or multi-layer materials. To efficiently dissipate the heat, one or more heat pipes  7  are included to be sandwiched between the heat conductive plate  1  and the heat-dissipating fin set  2 , as shown in  FIGS. 1 and 3 . In this case, the top surface of the heat conductive plate  1  is not complete flat but with an indentation therein to receive the heat pipes  7 . In another case where a complete flat top surface of the heat conductive plate is desired, a notch may be defined in the bottom surface of the heat-dissipating fin set  2  rather than in the top surface of the heat conductive plate  1  to receive the heat pipes  7 . 
     The heat-dissipating fin set  2  may be made in the aluminum extrusion process or made by punched metal sheets, for example: copper sheets or aluminum sheets. Preferably, the heat-dissipating fin set  2  is made up of a plurality of copper sheets or aluminum sheets. As shown in  FIGS. 2 and 3 , the heat-dissipating fin set  2  is composed of a plurality of heat-dissipation fins  21  parallel with one another. Each of the fins  21  has a bottom edge placed on the top surface of the heat conductive plate  1  and a top edge defining two concaves therein. The concaves  210  of the top edge of the fin  21  stand in a row to co-define a long, straight channel  22 , as shown in  FIG. 2 . The two channels  22  are parallel to each other to receive the two liners  3 . In other examples, different quantity of the concave(s) for each one of the fins  21  may be used to create one or more channels  22  for receiving one or more liners  3 . The quantity of the liner(s)  3  depends on that of the fastener(s)  4  which may be one or more. 
     As shown in  FIGS. 1 to 3 , each of the fasteners  4  includes a curled section  40  and two legs  41  joined to opposite ends of the curled section  40 . The curled section  40  is elastically deformable and has at least one troughs  401  pressing against a top surface of the heat-dissipating fin set  2  and at least one crests  402  spaced apart from the top surface of the heat-dissipating fin set  2 . Each of the liners  3 , preferably made of a conductive metal, includes a lining plate  30 . The lining plate  30  is received in the channel  22  of the heat-dissipating fin set  2  and is pressed by the curled section  40  of the fastener  4 . Specifically, the lining plate  30  has a flat bottom surface pressing against a bottom surface of the channel  22  and a flat top surface being pressed by the trough  401  of the curled section  40 . 
     Referring to  FIGS. 2 and 3 , each of the two legs  41  of the fastener  4  has a clasping member  410  to be fastened on the heat conductive plate  1 . Practically, each clasping member  410 is a hook. The two fasteners  4  include four clasping members  410  in total. In order to receive the four clasping members  410 , the heat conductive plate  1  defines four vertical holes  10  and four horizontal holes  11  therein. The four vertical holes  10  are defined in the top surface of the heat conductive plate  1  and located at comers of the same. As for the four horizontal holes  11 , two are defined in one side surface of the heat conductive plate  1  while the other two are defined in the opposite side surface of the heat conductive plate  1 . As shown in  FIG. 2 , the four horizontal holes  10  are in vertical communication with the four vertical holes  11  respectively. The clasping members  410 , namely the hooks, are able to be inserted into the respective vertical holes  11  and then hooked in the respective horizontal holes  10 . In such a manner, each of the fasteners  4  can be easily, quickly and securely fastened on the heat conductive plate  1  because the clasping members  410  are safely hidden in the respective vertical and horizontal holes  10  and  11  from being touched or loosen by others. On the contrary, each one of the clasping members  410  can be pushed inward by insertion of an insert into the horizontal hole  11  so as to allow the leg  41  together with its clasping member  410  to be removed from the horizontal holes  10 , and therefore to dismantle the fastener  4 . 
     As can be seen in  FIG. 2 , the clasping members  410  of the legs  41  of the fasteners  4  are fastened on the heat conductive plate  1 . At this time, each curled section  40  is tighten by the opposite legs  41  such that the troughs  401  of the curled section  40  of the fastener  4  can tightly press against the lining plate  30 . Therefore, the heat-dissipating fin set  2  can be tightly pressed against the heat conductive plate  1  and secured on heat conductive plate  1  as a result of the fasteners  4 . Further, since the heat-dissipating fin set  2  and the heat conductive plate  1  are tightly bonded together, the heat transfer therebetween is greatly enhanced. No soldering is needed to connect the heat-dissipating fin set  2  and the heat conductive plate  1 , and therefore the manufacturing process is simplified and the cost are relatively reduced. Nevertheless, it is suggested to employ a thermal grease or thermal paste to be coated in between the heat-dissipating fin set  2  and the heat conductive plate  1  in order to further enhance the heat transfer. 
     The fasteners  4  are made of elastic metals. Preferably, the material of the fasteners  4  is relatively hard-to-deform by heat when compared with the heat-dissipating fin set  2 , for example: stainless, iron, copper, etc. As such, the heat-induced expansion between the heat-dissipating fin set  2  and the heat conductive plate  1  will further lead the trough  401  of the curled section  40  of the fastener  4  to tightly press against the heat-dissipating fin set  2 , and therefore enhance the heat dissipation efficiency. 
     The lining plate  30  of the liner  3  placed in between the curled section  40  of the fastener  4  and the heat-dissipating fin set  2  helps to laterally disperse the force executed by the curled section  40  to a larger area instead of a certain points. Thus, the heat-dissipating fin set  2  is indirectly, evenly pressed by the curled section  40 , which leads to a closer contact between the bottom surface of the heat-dissipating fin set  2  and the top surface of the heat conductive plate  1 . 
     As shown in  FIGS. 3 and 4 , to avoid lateral displacement of the fasteners  4 , each of the liners  3  further includes two side plates  31  standing upright at two opposite edges of the top surface of the lining plate  30 . The exterior surfaces of the two side plates  31  of the liner  3  abut against opposite side surfaces of the channel  22  of the heat-dissipating fin set  2 . The interior surfaces of the two side plates  3   1 abut against opposite side edges of the curled section  40  of the fastener  4 . 
     In another embodiment, the channel  22  defined in the heat-dissipating fin set  2  is omitted, when compared with the aforementioned embodiment. That is, the top surface of the heat-dissipating fin set  2  is complete flat. The cured section  40  of the fastener  4  directly presses on the flat top surface of the heat-dissipating fin set  2 . In the case where the top surface of the heat-dissipating fin set  2  is not flat enough, a lining plate  30  may be introduced in between the fastener  4  and the heat-dissipating fin set  2  to provide a better contact therebetween. Specifically, the lining plate  30  has a flat bottom surface pressing against the top surface of the heat-dissipating fin set  2  and a flat top surface being pressed by the trough  401  of the fastener  4 . 
     In yet another embodiment, the liner  3  is omitted, when compared with the first aforementioned embodiment. That is, the curled section  40  of the fastener  4  directly presses on the bottom surface of the channel  22  of the heat-dissipating fin set  2 . The opposite side surfaces of the channel  22  of the heat-dissipating fin set  2  abut against the opposite side edges of the curled section  40  of the fastener  4 . Preferably, the bottom surface of the channel  22  is quite even so that the curled section  40  can evenly press toward the heat-dissipating fin set  2 . 
     It will be appreciated that although a particular embodiment of the invention has been shown and described, modifications may be made. It is intended in the claims to cover such modifications which come within the spirit and scope of the invention.