Abstract:
A heat sink mounting assembly includes a retention module ( 80 ) accommodating a heat sink ( 50 ) therein, and two retaining units ( 10 ) cooperating with the retention module to secure the heat sink therein. Each retaining unit includes a retaining clip ( 20 ) engaging with the retention module, and a pressing body ( 40 ) attached to the retaining clip. The pressing body includes a pressing portion ( 42 ) urging against the heat sink, and two releasing arms ( 46 ) each having a spring finger ( 48 ) snappingly engaging with the retaining clip when the pressing body is pressed toward the heat sink. When the releasing arms are squeezed, the spring fingers disengage from the retaining clip, and the pressing portion is released from the heat sink.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to mounting apparatuses, and more particularly to a mounting assembly for readily mounting a heat sink onto a heat-generating component such as a Central Processing Unit (CPU).  
           [0003]    2. Prior Art  
           [0004]    With the continuing development of computer electronics technology, new electronic packages such as the latest CPUs can perform more and more functions. Heat generated by these modern electronic packages has increased commensurately. Therefore, bigger and heavier heat sinks are becoming increasingly necessary to efficiently remove the heat from the electronic packages.  
           [0005]    A conventional heat sink assembly is disclosed in U.S. Pat. No. 5,464,054. In this kind of heat sink assembly, a clip made from a single metal wire is positioned in a groove of a heat sink for mounting the heat sink to an electronic package. Two resilient arms extend from opposite ends of the clip in directions substantially perpendicular to each other. A distal end of each arm is bent to form a hook engaging in a corresponding receiver formed on a frame or socket that holds the electronic package, thereby fastening the heat sink to the electronic package. However, selecting a wire clip with an appropriate diameter can be problematic. If the wire is too thin, the clip cannot provide a sufficient spring force to hold the heat sink, and the heat sink is prone to be displaced when the assembly is subjected to vibration or shock. If the wire is too thick, an unduly large force is required to engage the clip into the corresponding receivers. Additionally, a tool is generally required for installation or removal of the clip, which makes these processes excessively time consuming. Furthermore, the tool is liable to slip during use, which can cause damage to other components adjacent the electronic package. All these difficulties reduce the efficiency of assembly in mass production facilities. Reduced efficiency is translated into increased costs.  
           [0006]    Another kind of conventional heat sink assembly is shown in FIG. 4. The heat sink assembly comprises a socket  500 , an electronic package  400  located on the socket  50 , and a heat sink  300  fastened onto the electronic package  400  by a clip made from metal strips. The clip comprises a pressing body  100 , and an operation body  200  cooperating with the pressing body  100 . The pressing body  100  comprises a main pressing portion  120 , and an arm  140  extending generally perpendicularly from an end of the pressing portion  120 . A locking opening  160  is defined in the arm  140 . The operation body  200  defines a connecting hole  220  movably receiving an opposite end of the pressing portion  120 , so that the operation body  200  is movably attached to the opposite end of the pressing portion  120 . A locking slot  240  is defined in the operation body  200 , below the connecting hole  220 . The socket  500  forms two ears  520  at opposite sidewalls thereof, corresponding to the locking opening  160  and the locking slot  240  respectively. In assembly, one ear  520  of the socket  500  is received in the locking opening  160  of the arm  140 . The pressing portion  120  is arranged on a base  320  of the heat sink  300  between a plurality of fins that extends from the base  320 . The operation body  200  is then pressed downward, so that the locking slot  240  receives the other ear  520  of the socket  50  therein. The pressing portion  120  thus deforms and exerts force on the heat sink  300 , thereby retaining the heat sink  300  against the electronic package  400 . However, in assembly of the operation body  200  to the corresponding ear  520 , a user needs to press the operation body  200  downward with one hand, and pull the operation body  200  inwardly with the other hand at the same time, so that the locking slot  240  receives said other ear  520 . A corresponding two-handed operation is required in disassembly of the operation body  200  from the corresponding ear  520 . The operation body  200  is generally small. It can be difficult for the user to operate the small operation body  200  with both hands, especially in a narrow space inside an electronic enclosure. Therefore, even though the strip clip has improved retaining capability in comparison with the wire clip described above, the strip clip still has relatively poor operability.  
           [0007]    An improved heat sink mounting apparatus which can provide both good retaining capability and good operability is desired.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, an object of the present invention is to provide a heat sink mounting assembly for readily installing or removing a heat sink on or from an electronic package such as a CPU.  
           [0009]    Another object of the present invention is to provide a heat sink mounting assembly for securely mounting a heat sink on an electronic package such as a CPU.  
           [0010]    To achieve the above-mentioned objects, a heat sink mounting assembly in accordance with a preferred embodiment of the present invention comprises a retention module mounted on a circuit board, and a pair of retaining units cooperating with the retention module for securing a heat sink on an electronic package such as a CPU. The retention module comprises four columns cooperatively defining a space therebetween accommodating the heat sink therein. Each of the retaining units comprises a retaining clip having first and second legs releasably engaging with two corresponding columns, and a pressing body attached to the retaining clip. The pressing body comprises a pressing portion disposed between the retaining clip and the heat sink. An operation tab extends outwardly from a distal end of the pressing body. A pair of parallel releasing arms depends from the pressing body. A spring finger extends from each releasing arm. When the operation portion is pressed toward the heat sink, the pressing portion of the pressing body urges against the heat sink to secure the heat sink in the space of the retention module, and the spring fingers engage with the retaining clip to retain the pressing body in a locked position. When the releasing arms are squeezed, the spring fingers disengage from the retaining clip to release the pressing body from the locked position, and the pressing portion is released from the heat sink.  
           [0011]    Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of the preferred embodiment of the present invention with attached drawings, in which: 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an exploded, isometric view of a heat sink mounting assembly in accordance with the preferred embodiment of the present invention, together with a heat sink, and a CPU located on a printed circuit board, the heat sink mounting assembly comprising a retention module attached on the printed circuit board, and a pair of retaining units for cooperating with the retention module;  
         [0013]    [0013]FIG. 2 is an exploded, enlarged, isometric view of one of the retaining units of the heat sink mounting assembly of FIG. 1, but viewed from a different aspect;  
         [0014]    [0014]FIG. 3 is an assembled view of FIG. 1, showing the retaining units in respective locked positions; and  
         [0015]    [0015]FIG. 4 is a schematic, exploded, isometric view of a conventional heat sink assembly. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    [0016]FIG. 1 illustrates a heat sink mounting assembly in accordance with the preferred embodiment of the present invention, together with a printed circuit board  70  (PCB), an electronic package such as a CPU  60  attached on the PCB  70 , and a heat sink  50  for attaching on the CPU  60 . The heat sink  50  comprises a base  52  for thermally contacting a top surface of the CPU  60 , and a plurality of cooling fins  54  extending upwardly from the base  52 . Each fin  54  defines a pair of cutouts (not labeled) in opposite top comers thereof respectively. The fins  54  thus cooperatively define a pair of shoulders  56  at opposite sides of the heat sink  50  respectively.  
         [0017]    The heat sink mounting assembly according to the preferred embodiment comprises a retention module  80  attached to the PCB  70 , and a pair of retaining units  10  cooperating with the retention module  80  to attach the heat sink  50  on the CPU  60 .  
         [0018]    The retention module  80  comprises a base frame  82  surrounding the CPU  60 , and four columns  84  extending upwardly from four comers of the base frame  82  respectively. The frame  82  and columns  84  cooperatively define a generally rectangular space (not labeled) therebetween, for accommodating the heat sink  50  therein. A locking hole  840  is defined in each column  84 .  
         [0019]    Referring also to FIG. 2, each retaining unit  10  comprises a retaining clip  20 , and a pressing body  40  attached to the retaining clip  20 . The retaining clip  20  comprises an elongated main body  22 , a first leg  24  extending downwardly from a first end of the main body  22 , and a second leg  26  attached to an opposite second end of the main body  22 . The main body  22  comprises a horizontal top wall  222 , and a pair of vertical sidewalls  224  extending downwardly from opposite long sides of the top wall  222 . The top wall  222  and the sidewalls  224  cooperatively define a channel (not labeled) therebetween. The first leg  24  extends downwardly from a first end of the top wall  222 . A distal end of the first leg  24  is bent inwardly and upwardly to form a first hook  242 . A notch  226  is defined in a first end of each sidewall  224 . Each notch  226  is bounded by the first end of the top wall  222  and a top portion of the first leg  24 . A pair of mounting holes  229  is defined in second ends of the sidewalls  224  that are opposite from the first ends thereof, respectively. The mounting holes  229  are opposite each other across the channel. A pair of first protrusions  264  is outwardly formed from opposite edges of a top portion of the second leg  26  respectively. The first protrusions  264  are extended into the mounting holes  229 , thereby pivotably mounting the second leg  26  to the sidewalls  224 . A distal end of the second leg  26  is bent inwardly and upwardly to form a second hook  262 . A longitudinal slot  225  is defined in the top wall  222 , near a second end of the top wall  222  that is opposite from the first end thereof. A latch opening  228  is defined in the second end of the top wall  222 .  
         [0020]    The pressing body  40  is generally V-shaped, and comprises a central pressing portion  42 , and first and second portions  41 ,  43  extending slantingly upwardly from opposite ends of the pressing portion  42  respectively. A pair of second protrusions  45  extends outwardly in opposite directions from a distal end of the first portion  41 . The second protrusions  45  correspond to the notches  226  of the main body  22  of the retaining clip  20 . An operation tab  44  extends slantingly from a distal end the second portion  43 . A pair of parallel releasing arms  46  extends downwardly from opposite sides of the operation tab  44  respectively. Each releasing arm  46  inwardly forms an L-shaped spring finger  48 . The spring fingers  48  partly overlap each other between the releasing arms  46 . A bottom free end of each spring finger  48  forms a barb  480 , with the barbs  480  of the spring fingers  48  being generally symmetrically opposite to each other. A combined distance spanned by the barbs  480  is greater than a corresponding width of the latch opening  228  of the main body  22  of the retaining clip  20 .  
         [0021]    In assembly of each retaining unit  10 , the first portion  41  is inserted into the channel of the main body  22  of the retaining clip  20  via the slot  225 . The second protrusions  45  of the first portion  41  are engaged into the notches  226  of the main body  22 . The first protrusions  264  of the second leg  26  are then pivotably received in the mounting holes  229  of the main body  22 . The retaining units  10  are thus assembled.  
         [0022]    Referring also to FIG. 3, in assembly of the heat sink mounting assembly, the heat sink  50  is placed in said space of the retention module  80 . The base  52  of the heat sink  50  is in loose contact with the top surface of the CPU  60 .  
         [0023]    The retaining units  10  are then placed on the shoulders  56  of the heat sink  50  respectively. The first and second hooks  242 ,  262  of the first and second legs  24 ,  26  of each retaining unit  10  are loosely engaged in corresponding locking holes  840  of the columns  84  of the retention module  80 . The operation tab  44  of the pressing body  40  is pressed down toward the retaining clip  20 , thereby deforming the pressing body  40  toward the heat sink  50 . When the barbs  480  of the spring fingers  48  reach the latch opening  228  of the main body  22 , the spring fingers  48  elastically deform slightly as tapered edges of the barbs  48  ride over edges of the main body  22  at the latch opening  228 . Once the tapered edges of the barbs  480  have completely ridden over said edges of the main body  22 , the releasing arms  46  elastically rebound, and the spring fingers  48  return to their original states. That is, the barbs  480  are snappingly engaged under the main body  22  at the latch opening  228 . Simultaneously, the pressing portion  42  of the pressing body  40  resiliently urges the corresponding shoulder  56  of the heat sink  50 , and the first and second hooks  242 ,  262  are resiliently engaged in the locking holes  840  of the retention module  80 . The heat sink  50  is thus firmly secured on the CPU  60  in said space of the retention module  80  by the retaining units  10 .  
         [0024]    To remove the heat sink  50 , the releasing arms  46  of the pressing body  40  of each retaining unit  10  are squeezed together, the second portion  43  rebounds to its original orientation, and the barbs  480  of the spring fingers  48  move up and out from the latch opening  228  of the main body  22 . The first and second hooks  242 ,  262  are disengaged from the locking holes  840  of the retention module  80 . The retaining units  10  are removed from the heat sink  50 . The heat sink  50  is then readily removed from said space of the retention module  80 .  
         [0025]    In the heat sink mounting assembly of the present invention, each retaining unit  10  is engaged with the heat sink  50  and the retention module  80  merely by pressing the operation tab  44  of the pressing body  40 . Further, each retaining unit  10  is detached from the heat sink  50  and the retention module  80  merely by squeezing the releasing arms  46  of the pressing body  40 . No tools or other actuation means are required. The heat sink mounting assembly provides easy and convenient operation.  
         [0026]    It is noted that in the preferred embodiment of the present invention, the second leg  26  is a separate component prior to attachment to the main body  22 . In an alternative embodiment, the second leg  26  integrally extends from the second end of the main body  22 .  
         [0027]    Furthermore, in the preferred embodiment of the present invention, the retention module  80  comprises four columns  84  each defining a locking hole  840  therein. The first and second legs  24 ,  26  of each retaining unit  10  respectively have first and second hooks  242 ,  262  engaging in corresponding locking holes  840 . In a further alternative embodiment, each retaining unit  10  may instead cooperate with other retention means such as a CPU socket on which the CPU  60  is mounted. In such case, the CPU socket defines a pair of locking holes in each of opposite sides thereof, the locking holes receiving respective first and second hooks  242 ,  262  of the retaining clips  10  therein.  
         [0028]    It is understood that the invention may be embodied in other forms without departing from the spirit thereof. The above-described examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given above.