Patent Publication Number: US-2010128440-A1

Title: Heat sink assembly having a clip

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to heat sink assemblies and, more particularly, to a heat sink assembly having a clip which can be easily and accurately assembled to the heat sink. 
     2. Description of Related Art 
     A heat sink assembly cools an electronic device. The heat sink assembly generally includes a heat sink attached to an outer surface of the electronic device to facilitate dissipation of heat therefrom and a clip fastening the heat sink to the electronic device. The heat sink includes a base and a plurality of fins extending therefrom. A channel is defined between every two adjacent fins. The clip extends through one of the channels and abuts a top surface of the base. 
     When the clip is mounted on the heat sink, the heat sink is punched by a tool to have a portion thereof deformed to engage with the clip. The punched part of the heat sink may be broken from the heat sink during the punching process whereby the clip cannot be attached to the heat sink. On the other hand, the punched part may too tightly engage with the clip, whereby the clip can not properly rotate relative to the heat sink and accordingly cannot properly secure the heat sink to the electronic device. 
     What is needed, therefore, is a heat sink assembly having a clip which can be easily and accurately assembled to the heat sink to solve the problems of the prior art mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  is an assembled view of a heat sink assembly in accordance with an embodiment of the disclosure, wherein the heat sink assembly is assembled to a printed circuit board. 
         FIG. 2  is an exploded view of the heat sink assembly of  FIG. 1 , wherein the heat sink assembly is disassembled from the printed circuit board. 
         FIG. 3  is cutaway view of the heat sink assembly of  FIG. 1 . 
         FIG. 4  is a side view of the heat sink assembly, wherein a clip of the heat sink assembly is unlocked. 
         FIG. 5  is a side view of the heat sink assembly, wherein the clip of the heat sink assembly is locked. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Referring to  FIGS. 1-2 , a heat sink assembly comprises a heat sink  10  and a clip  30 . The heat sink  10  thermally contacts an electronic element  51  on a printed circuit board  50 . The clip  30  spans the heat sink  10  and engages with two clasps  53  located on the printed circuit board  50  and near two diagonal corners of the heat sink  10  to secure the heat sink  10  on the printed circuit board  50 . 
     The heat sink  10  is integrally made of metal with high heat conductivity such as copper, aluminum or an alloy thereof. The heat sink  10  comprises a rectangular base  11  and a plurality of fins  13  extending upwardly from a top surface of the base  11 . The fins  13  are parallel and spaced from each other to constitute a plurality of rows. An elongated channel (not labeled) is defined between every two adjacent rows of fins  13  along a width or a length axis of the base  11 . The fins  13  comprise two rows of first fins  13   a,  two rows of second fins  13   b,  and a plurality of rows of third fins  13   c.  The first, second and third fins  13   a,    13   b,    13   c  are arranged in neat rows along the width axis of the base  11  of the heat sink  10 . The first, second and third fins  13   a,    13   b,    13   c  are symmetrical about a central surface at a center of the heat sink  10  along the width axis of the base  11  and perpendicular to the top surface of the base  11 . 
     The first fins  13   a  are located at a central portion of the base  11  of the heat sink  10 . Each of the first fins  13   a  comprises an elongated first fin body  131  and a protrusion  133  extending inwardly from an inner surface thereof. The protrusions  133  facing each other are formed at lower portions of the adjacent first fins  13   a  of the two rows. The protrusions  133  define a straight groove  135  therebetween, receiving the clip  30  therein. The groove  135  is narrower than a gap between top portions of the first fins  13   a.  Strength of the lower portions of the first fins  13   a  is reinforced by the protrusions  133 . 
     The two rows of second fins  13   b  are located at opposite sides of the first fins  13   a.  Each of the second fins  13   b  comprises an elongated second fin body  134  and a cuneate ridge  137  angling downwardly and inwardly from an inner surface of the second fin body  134 . The ridges  137  of the two second fins  13   b  face the first fins  13   a.  The ridges  137  are disposed at the same height above the protrusions  133  of the first fins  13   a.  The ridges  137  abut downwardly against the clip  30  when the clip  30  is mounted to the heat sink  10 . The third fins  13   c  are elongated and located at opposite sides of second fins  13   b.  The first, second and third fins  13   a,    13   b,    13   c  cooperatively dissipate heat from the heat sink  10 . 
     The clip  30  is a wire clip integrally made of metal wire. The clip  30  comprises a straight pressing member  31 , two trapezoidal engaging members  33  angling upwardly from opposite ends of the pressing member  31  toward two different directions, two straight extending members  35  extending outwardly from free ends of the engaging members  33 , and two locking arms  37  perpendicularly extending outwardly from free ends of the extending members  35  and oriented towards generally opposite directions. The clip  30  is symmetrical about the pressing member  31 . 
     The pressing member  31  of the clip  30  is snugly received in the groove  135  between the first fins  13   a  of the heat sink  10 . The engaging members  33  of the clip  30  are spaced from each other. Each of the engaging members  33  comprises a straight resisting portion  333 , a first connecting portion  331  and a second connecting portion  335 . The resisting portion  333  is located at a side of the pressing member  31 . The first connecting portion  331  angles downwardly from an inner end of the resisting portion  333  and connects with an end of the pressing member  31 . The second connecting portion  335  angles downwardly from an outer end of the resisting portion  333  and connects with an end of the extending member  35 . The resisting portions  333  of the two engaging members  33  are on opposite sides of the pressing member  31  and parallel thereto. The resisting portions  333  abut the ridges  137  and the inner surfaces of the second fins  13   b  of the heat sink  10  to prevent movement thereof along the length axis of the base  11  thereof. The first and second connecting portions  331 ,  335  of each of the two engaging members  33  sandwich one of the corresponding first fins  13   a  of the fins  13  of the heat sink  10  therebetween to prevent the heat sink  10  from moving along the width axis of the base  11  of the heat sink  10 . Here, a distance between the first and second connecting portions  331 ,  335  of each of the two engaging members  33  approaches a width of each first fin  13   a  of the fins  13 . 
     The extending members  35  of the clip  30  and the pressing member  31  of the clip  30  are collinear and disposed at the same height. The locking member  37  comprises a straight locking arm  371  and a hook  373  angling laterally from a free end of the locking arm  371 . The locking arms  371  are perpendicular to the extending members  35 . The two locking arms  371  extend towards different directions. The hooks  373  engage the clasps  53  of the printed circuit board  50 , when the clip  20  is used to secure the heat sink  10  to the printed circuit board  50  so that the heat sink  10  can intimately engage with the electronic element  51 . 
     Referring to  FIGS. 3-5  also, in assembly, the heat sink  10  is disposed on a top surface of the electronic element  51  of the printed circuit board  50 . The clip  30  is arranged on the top surface of the base  11  from top to bottom of the fins  13 . Thus, the pressing member  31  of the clip  30  extends through the first fins  13   a  of the fins  13  of the heat sink  10  and is pivotably engaged in the groove  135  of the heat sink  10 . Each of the resisting members  33  spans the corresponding first fin  13   a  of the fins  13  of the heat sink  10  and abuts an inclined top surface of the corresponding ridge  137  of the second fin  13   b  of the fins  13  of the heat sink  10 . In this state, one first fin  13   a  is sandwiched between the first and second connecting portions  331 ,  335  of one corresponding engaging member  33 . Inner ends of the extending members  35  are pivotably engaged in the groove  135  of the heat sink  10 . Outer ends of the extending members  35  and the locking members  37  are beyond the base  11  and located at lateral sides of the base  11  of the heat sink  10 . The locking arms  371  of the locking members  37  are pressed downwardly until the hooks  373  of the locking members  37  engage the clasps  53  of the printed circuit board  50 . Meanwhile, the extending members  35  rotate along opposite directions, the resisting portions  333  of the engaging members  33  slip downwardly along the inclined top surfaces of the ridges  137  of the second fins  13   b  of the fins  13  of the heat sink  10  until the resisting portions  333  are received in angles defined by bottom ends of the ridges  137  and the second fins  13   b.  Thus, the clip  30  provides a steady locking force to maintain tight attachment of the heat sink  10  to the electronic element  51  of the printed circuit board  50 . As a result, the heat sink  10  is fixed on the printed circuit board  50  to have intimate contact with the electronic element  51 . In the present disclosure, the heat sink  10  does not need being punched in order to mount the clip  30  to the heat sink  10 ; thus, the disadvantages of the prior can be avoided by the present disclosure. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.