Abstract:
Heat sink retention assemblies and related methods are described. In one embodiment, a system comprises a base, a handle rotatably mounted on the base, and heat sink retention structure joined with the handle and moveable by the handle between an opened and a closed position effective to secure a heat sink on a substrate.

Description:
BACKGROUND 
   Heat sink mechanisms can be used to remove heat from integrated circuit devices such as processors, application specific integrated circuits (ASICs) and the like. Many heat sink assemblies work by being physically secured to a printed circuit board (PCB) on which the integrated circuit devices are mounted. In operation, the heat sink assembly is placed into physical contact with an associated chip&#39;s package and works by providing a thermal path for heat which is generated by operation of the chip. 
   One way of mounting a heat sink to a printed circuit board is to sandwich the printed circuit board between the heat sink and a metal plate, and then use a number of screws to threadably connect the heat sink to the metal plate through material of the printed circuit board, thereby squeezing the printed circuit board between the metal plate and the heat sink. Another way to mount the heat sink to a printed circuit board is to use clips to clip the heat sink to the printed circuit board. 
   Using screws to affix a heat sink to a printed circuit board can be time consuming because it requires a person to physically connect each screw. Additionally, using screws can be problematic because unevenly applied force can cause stress to the printed circuit board and possibly damage the printed circuit board. In addition, this solution provides a number of loose parts which can become lost. 
   Using clips to affix a heat sink to a printed circuit board can also be time consuming because a person has to physically connect each clip. In addition, each clip has the potential to rattle loose thus compromising the mounting arrangement. 
   Yet other heat sink mounting solutions have involved the use of so-called cages. These cages tend to be bulky and difficult to maneuver around while installing the heat sink. In addition, some cages can block air flow through the enclosure or housing in which the heat sink is mounted which, in turn, can cause the internal enclosure temperature to rise. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a system that employs a heat sink retention assembly in an opened position in accordance with one embodiment. 
       FIG. 2  is an isometric view of a system that employs a heat sink retention assembly in a closed position in accordance with one embodiment. 
       FIG. 3  is a side elevational view of an exemplary link member and portions of a base plate in an opened position in accordance with one embodiment. 
       FIG. 4  is a side elevational view of an exemplary link member and portions of a base plate in a closed position in accordance with one embodiment. 
       FIG. 5  is an isometric exploded view of an exemplary heat sink retention assembly in accordance with one embodiment. 
       FIG. 6  is a view of an exemplary computer system with which the exemplary embodiments can be employed. 
   

   DETAILED DESCRIPTION 
   Overview 
   In accordance with the embodiments described herein, a heat sink retention assembly is provided that is easy to install and has a profile that promotes air flow through the enclosure in which it is mounted. In addition, in at least some embodiments, the heat sink retention assembly is “tool-less” in that once the heat sink retention assembly is placed into physical contact with the heat sink through a substrate such as a printed circuit board, no tools are needed to complete the affixation of the heat sink retention assembly to the printed circuit board and hence, the heat sink. Further, in at least some embodiments, heat sinks can be more reliably mounted on a printed circuit board by virtue of a simultaneous, multi-point connection that is achieved through one simple motion, as will become apparent below. 
   In at least some embodiments, once the heat sink retention assembly is mounted on an associated printed circuit board, there are no loose parts that might rattle or become lost during shipping or operation. Thus, the heat sink retention assembly is more reliable than those that have been used in the past. 
   Exemplary Embodiment 
     FIG. 1  shows a system, generally at  10 , that employs a heat sink retention assembly in accordance with one embodiment. In this example, system  10  comprises a heat sink  12  that is mounted to a printed circuit board  14  by virtue of a heat sink retention assembly  100 . Any suitable type of heat sink can be employed in connection with the inventive embodiments described herein. Accordingly, the specifically illustrated heat sink is not intended to limit application of the claimed subject matter to any one particular type of heat sink. 
   In this particular example, printed circuit board  14  includes an integrated circuit chip  16  (shown in dashed lines), which can be any suitable type of chip such as a processor, ASIC and the like. The chip can be received by a socket (not illustrated) which is, in turn, mounted on the printed circuit board  14 , as will be appreciated by the skilled artisan. 
   In accordance with the illustrated and described embodiment, heat sink retention assembly  100  comprises structure that is utilized to retain a heat sink against the printed circuit board  14 . In the illustrated and described example, the heat sink retention structure comprises a base plate  200  which is mounted on or otherwise affixed to printed circuit board  14 , a handle  300  which is rotatably mounted on base plate  200 , and a plurality of link members  400  each of which is pivotably mounted on handle  300  for movement between an opened or first position ( FIG. 1 ) and a closed or second position ( FIG. 2 ). In the illustrated and described embodiment, each of the link members comprises a pair of slots  402 ,  404  which are utilized to guide link member movement relative to the base plate  200  when the heat sink retention assembly  100  is moved from the opened position to the closed position, as will become apparent below. In this particular example, each slot of a slot pair has a different shape. 
   Exemplary Base Plate 
   Referring to  FIGS. 1 and 5 , base plate  200  comprises a central body portion  202  and a plurality of extensions  204 ,  206 ,  208  and  210  joined with the central body portion  202  and extending away therefrom. In the illustrated and described embodiment, central body portion  202  includes a centrally located pin  202   a  that is mateable with a suitably dimensioned hole on handle  300  to permit the handle to be rotated thereabout relative to the base plate  200  between the opened and closed positions. Although four extensions are shown, any suitable number of extensions can be employed. 
   In the illustrated and described embodiment, extensions  204 ,  208  extend along a first common line l 1  generally away from each other, and extensions  206 ,  210  extend along a second common line l 2  generally away from each other. In this embodiment, the extensions collectively define an “X” shape which gives the base plate an X-like shape. 
   In accordance with one embodiment, and as can best be appreciated from the exploded view of  FIG. 5 , each extension  204 ,  206 ,  208  and  210  extends away from central body portion  202  along a respective extension body  204   a ,  206   a ,  208   a ,  210   a  toward a respective terminus  204   b ,  206   b ,  208   b  and  210   b . Proximate each respective terminus  204   b ,  206   b ,  208   b  and  210   b , a through hole is provided and is configured to receive a cylinder  205 , such as a metal cylinder, that is generally fixedly mounted on the base plate  200 . 
   In the illustrated and described embodiment, each cylinder serves a couple of purposes. First, the cylinders serve a restraint function during operation of the heat sink retention assembly  100  which serves to prevent undesired movement that can prevent proper pin engagement, as will become apparent below. Second, the cylinders serve as guide holes for pins that are mounted on the heat sink  12 . Exemplary pins are shown at  12   a  in  FIG. 1 . In operation, the heat sink pins are inserted through respective cylinders mounted on each extension and are captured by and ride in a respective slot  404  in each link member, described in detail below. 
   In accordance with one embodiment, each extension body is generally flat or planar along a majority of its length. Toward the terminus of each extension body, material of the extension bends generally away from the majority of the extension body to define a ramp  204   c ,  206   c ,  208   c  and  210   c . Each ramp is designed to provide a degree of lift to its associated link member  400  and to load an associated heat sink pin  12   a  which, in turn, serves to urge the heat sink against its associated integrated circuit chip, as will become apparent below in the discussion of  FIGS. 3 and 4 . Although the ramp can be disposed at any suitable angle relative to the majority of its extension body, an angle in the range from between 20 to 45 degrees has been found suitable for providing a smooth transition from the open to the closed position. In accordance with one embodiment, each extension body terminus can have a respective divot  204   d ,  206   d ,  208   d  and  210   d  which serves to reduce the tendency of the link member  400  to dig into the terminus, due to bending, when the heat sink retention assembly  100  is in transition to the closed position. 
   Although any suitable material, such as plastics and the like can be utilized to form base plate  200 , in at least one embodiment, the base plate is formed from a metal material such as cold rolled steel. Using such a material provides a desirable degree of strength and provides a suitable substrate on which an industrial adhesive can be used to fixedly bond the base plate onto the printed circuit board. 
   Exemplary Handle 
   In accordance with at least one embodiment, handle  300  comprises a central body portion  302  having a hole that is dimensioned to receive central pin  202   a  on base plate  200 , and a grippable extension  304  joined with the central body portion and extending generally away therefrom. Although the handle can be formed from any suitable material, such as plastics and the like, in at least one embodiment, the handle is formed from cold rolled steel which provides a desirable degree of strength. 
   In accordance with the illustrated and described embodiment, central body portion  302  has a plurality of through holes about its periphery, each of which receives a cylinder or pin  306 . The cylinders or pins are designed to serve as connection points for a respective link member that allows an associated link member to be pivoted between the opened and closed positions, as will become apparent below. 
   In accordance with the described embodiment, the handle is grippable and of suitable length to provide a mechanical advantage so that the handle can be moved between the opened position ( FIG. 1 ) and the closed position ( FIG. 2 ). 
   Exemplary Link Members 
   In the illustrated and described embodiment, four link members  400  are provided and are connected to handle  300  for simultaneous movement with the handle when the handle is moved between the opened position ( FIG. 1 ) and the closed position ( FIG. 2 ). In the illustrated and described embodiment, each link member is connected to handle  300  by virtue of the cylinders or pins  306  mentioned just above. As noted above, each link member comprises a pair of slots  402 ,  404 . In the illustrated example, slot  402  comprises a first slot, and slot  404  comprises a second slot. Each link member also comprises a flange  406  with a through hole that receives an associated cylinder or pin  306 . 
   In accordance with one embodiment, slot  402  is generally arcuate or J-shaped and receives a screw or pin  402   a  which is connected to base plate  200 . Each of pins  402   a  rides in its associated slot when the handle is moved between the opened and closed position. The effect of the slot/pin arrangement just described is to allow the link members to pivot “over center” which can prevent accidental unlocking since self-loading holds the system in the locked or closed position. More specifically, when the heat sink retention assembly  100  is in the opened position, each of the screws  402   a  is disposed proximate the top of the “J” of the J-shaped slot, as shown in  FIG. 1 . When the handle is moved to the locked or closed position, the link member pivots over center and moves the bottom part of the “J” to engage with and lock an associated screw  402   a  in place, as shown in  FIG. 2 . 
   Movement of link members  400  in connection with handle  300  movement can be seen from a comparison of  FIGS. 1 and 2 . There, in the opened position ( FIG. 1 ), each of the associated screws  402   a  is disposed proximate the top of each associated “J” slot. In the closed position ( FIG. 2 ), each of the link members  400  has been pivoted over center to move the bottom part of each “J” into contact with each associated screw to thereby capture the screw, as noted above. 
   In accordance with one embodiment, slot  404  is generally keyhole-shaped and comprises an opening that is situated over an associated cylinder that is received in an associated base plate extension terminus  204   b ,  206   b ,  208   b  and  210   b , and a narrow slot portion that extends away from the opening generally towards the J-slot  402 . 
   In operation, each slot  404  receives a pin  12   a  that is connected to an associated heat sink. As the handle is moved from the opened to the closed position, each pin  12   a  moves from the keyhole opening and into the narrow slot portion, as will become apparent below. 
   The link members can be formed from any suitable material, such as plastics and the like. In accordance with one embodiment, each link member is formed from stainless steel which provides a fortified construction that is less likely to yield under load. 
     FIG. 6  shows an exemplary computer system that can utilize or otherwise contain system  10 . 
   In Operation 
   In accordance with the described embodiment, a heat sink can be mounted on an associated substrate such as a printed circuit board by virtue of a simultaneous, multi-point connection that is achieved through one simple motion. In the illustrated and described embodiment, four heat sink connection points are provided. 
   More specifically, heat sink retention assembly  100  is mounted on a substrate such as printed circuit board  14  ( FIG. 1 ) by affixing or otherwise bonding base plate  200  on printed circuit board  14 . Once the heat sink retention assembly  100  is mounted on the printed circuit board and after an integrated circuit chip, such as chip  16  is installed on the printed circuit board, the heat sink is installed on the printed circuit board by inserting each of the heat sink pins  12   a  through mating holes on the printed circuit board and associated cylinders  205  that are received in base plate extensions  204 ,  206 ,  208  and  210  as noted above. Inserting the pins  12   a  through the mating holes as just described moves each head of an associated pin  12   a  into an associated opening of an associated slot  404 . At this point, the heat sink retention assembly  100  is in the opened position and the heat sink is fully seated. 
     FIGS. 1 and 3  show the heat sink retention assembly  100  in the opened position.  FIG. 3  is a side elevational view that shows an individual link member  400  with a pin  12   a  received in the opening of slot  404 , and a pin  402   a  received in the upper portion of the J-slot. Notice that in the opened position, the link member  400  lies in a generally flush disposition atop base plate extension  204 . In accordance with the illustrated and described embodiment, in the opened position the link member  400  is not yet engaged with ramp  204   c.    
   To close the heat sink retention assembly  100 , handle  300  is moved or rotated so that each of the link members  400  pivots over center, moving each pin  402   a  within the J-slot  402  to lock the pin  402   a  in the bottom portion of the J slot. In the illustrated and described embodiment, handle  300  is moved in a plane P ( FIG. 1 ). Simultaneously with this rotational handle movement, and as perhaps best illustrated in  FIG. 4 , link members  400  are moved generally along the length of each extension which causes the link member to engage the ramp  204   c  and ride up on the ramp. When the link member rides up on the ramp  204   c , the bottom portion of each pin  12   a  is loaded by the link member along a vector ν which is generally orthogonal to plane P. This, in turn, causes the heat sink  12  ( FIG. 1 ) to be moved in a direction towards printed circuit board  14  to thereby urge the heat sink against the integrated circuit chip  16 , to thus establish a thermal interface for promoting heat removal from the chip. Thus, the rotational handle movement is translated into a heat sink capture movement. The J-shape of each slot  402  allows the system to travel to such a point that loading creates an over center condition thereby locking the system into the closed position. 
   CONCLUSION 
   In accordance with the embodiments described above, a heat sink retention assembly is provided that is easy to install and has a profile that promotes air flow through the enclosure in which it is mounted. In addition, in at least some embodiments, the heat sink retention assembly is “tool-less” in that once the heat sink retention assembly is placed into physical contact with the heat sink through the printed circuit board, no tools are needed to complete the affixation of the heat sink retention assembly to the printed circuit board and hence, the heat sink. Further, in at least some embodiments, heat sinks can be more reliably mounted on a printed circuit board by virtue of a simultaneous, multi-point connection that is achieved through one simple motion. In at least some embodiments, once the heat sink retention assembly is mounted on an associated printed circuit board, there are no loose parts that might rattle loose during shipping or operation. Thus, the heat sink retention assembly is more reliable than those that have been used in the past. 
   Although the inventive concepts have been described in language specific to structural features and methodological steps, it is to be understood that the inventive concepts defined in the appended claims are not necessarily limited to the specific features or steps described. Rather, the specific features and steps are disclosed as preferred forms of implementing the claimed inventive concepts.