Patent Document

BACKGROUND 
     This invention relates generally to heat sinks for integrated circuits. 
     Because of the heat generated by some integrated circuits, an integrated circuit may be intimately associated with a heat transfer device that removes heat from an integrated circuit die. An integrated circuit die may be packaged and the package may be coupled to a heat transfer device. Alternatively, the die may be exposed for direct contact by the heat transfer device. A heat transfer device, such as a heat sink, has a high heat transfer coefficient. 
     Processors may become excessively hot during operation. This heat may ultimately result in damage to the processor and may adversely affect the speed of its operation. Thus, it is desirable to contact the processor with a heat transfer device that removes heat. 
     Heat transfer devices may be active or passive. An active heat transfer device normally includes a fan which forces air over the integrated circuit to increase its rate of heat transfer. A passive heat transfer device is generally a heat sink with desirable heat transfer characteristics. Combinations of active and passive heat transfer devices are commonly utilized. 
     Attaching the heat transfer device over an integrated circuit on a circuit board can become a relatively complex operation. Generally, it is desirable to enable the removal of the integrated circuit device from the heat transfer device. This facilitates assembly and repair of the heat transfer device and testing of the integrated circuit. 
     In many cases, the heat transfer device is relatively bulky. It is generally desirable to contact the integrated circuit device with the heat transfer device. Commonly, an integrated circuit electrically couples to a variety of contacts on a circuit board, for example using pins that engage slots in a socket or other carrier. Thus, the integrated circuit may be attached to the circuit board and the heat transfer device may be attached over the integrated circuit in a removable, electrically contacting engagement. Therefore, the connection of the integrated circuit to the circuit board and the association of the heat transfer device with the integrated circuit may become complex. 
     For example, in connection with some designs, the attachment of the various components may require the use of tools. The use of tools generally results in longer assembly time. The assembler must assemble components and then grab a tool to secure the components together. 
     It would be desirable to enable the connection of the heat transfer device to the integrated circuit holder without requiring the use of any tools. Moreover, it would be desirable to have a way to readily and easily associate these components with one another. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one embodiment of the present invention showing the placement of the integrated circuit; 
     FIG. 2 is a perspective view of the embodiment of FIG. 1 after placement of the integrated circuit; 
     FIG. 3 is a perspective view of the embodiment shown in FIG. 1 after the heat transfer device has been pivoted over the integrated circuit; 
     FIG. 4 is a perspective view of the embodiment of FIG. 3 showing the process of securing a heat transfer device to the integrated circuit; 
     FIG. 5 is a partial, enlarged cross-sectional view taken generally along the line  5 — 5  of FIG. 2; 
     FIG. 6 is a partial, enlarged cross-sectional view corresponding to FIG. 5 but taken generally along the line  6 — 6  in FIG. 3; 
     FIG. 7 is a partial, enlarged cross-sectional view taken generally along the line  6 — 6  in FIG. 3; 
     FIG. 8 is a partial, enlarged cross-sectional view corresponding to FIG. 7 but taken along the line  8 — 8  in FIG. 4; 
     FIG. 9 is a partial enlarged cross-sectional view taken generally along the line  8 — 8  in FIG. 4 after rotation of the heat transfer device to secure the heat sink to the integrated circuit; 
     FIG. 10 is an exploded view of the heat transfer device in accordance with one embodiment of the present invention; and 
     FIG. 11 is a side elevational view of the heat sink shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, an electronic device  10  may include an integrated circuit  22  secured within a holder  14  in turn secured to a circuit board  12 . A heat transfer device  35  may be secured to the holder  14  for pivotal movement around one of the edges of the holder  14 . The holder  14 , in one embodiment of the present invention, includes four sides  15  that define a frame around the integrated circuit  22 . Each corner of the holder  14  may be secured by a threaded fastener  16  to the circuit board  12 . In one embodiment of the present invention, the device  10  is a motherboard and the integrated circuit  22  is a processor. 
     In one embodiment of the present invention, the integrated circuit  22  includes an organic layer grid array (OLGA) package. However, other packaging techniques may be utilized. In the illustrated package, the integrated circuit die  24  is exposed. The integrated circuit  22  may be secured to a socket  20  within the frame  14 . The socket  20  may be secured directly to the circuit board  12  in one embodiment of the present invention. The socket  20  may include contacts (not shown) which mate with contacts (not shown) on the integrated circuit  22 . In one embodiment of the present invention, the socket  20  may include pins that engage slots in the integrated circuit  22 . However, any type of integrated circuit connection technique may be utilized. 
     The heat transfer device  35  may include a threaded heat sink member  38 , a heat sink mount  30 , an active heat transfer device  36 , an electrical connector  32  to supply power to the device  36 , and a heat sink  34 . In some embodiments, the active heat transfer device  36 , which may include a fan  44 , may not be included. While the heat sink  34  is shown as a pin type heat sink, any other heat sink design may be utilized including, for example, those that include fins. 
     As shown in FIG. 2, the integrated circuit  22  may be placed on the socket  20  within the holder  14  with the die  24  facing upwardly. The heat transfer device  35  may rest in the overcenter position shown in FIG.  2 . Interference between the holder  14  and the mount  30  may prevent further clockwise rotation from the position shown in FIG.  2 . 
     Referring to FIG. 3, the heat transfer device  35  may pivot counterclockwise around the pivotal connection  37  so that the pivotally mounted heat sink mount  30  rests on top of the holder  14 . The heat sink member  38  is then in direct contact with the die  24 , in accordance with one embodiment of the present invention. However, other integrated circuits  22  may be utilized and it is not essential (although it may be advantageous) that the heat sink member  38  directly contact the die  24 . 
     The pivotal connection  37  includes a slotted member  28 , shown in FIG. 5, connected to, or integral with, the heat sink mount  30 . An axle  46 , associated with the holder  14 , is journaled within an elliptical slot  47  inside the mount  30 . Because the slot  47  is elongated, relative movement is possible between the member  28  and the axle  46 . In other embodiments, the axle  46  may be included as part of the mount  30  and the member  28  may be a part of the holder  14 . In any case, the arrangement of the axle  46 , journaled within the member  28 , allows pivotal motion of the heat transfer device  35  around the side  15   b  of the holder  14  (from the position shown in FIG. 2) until the device  35  contacts the holder  14  in face-to-face abutment, as shown in FIG.  3 . 
     While a technique is described in which the mount  30 , heat sink  34 , and active heat transfer device  36  are pivoted as a unit, other techniques may also be used. For example, the mount  30  may be pivoted on its own, and other components may be thereafter secured to the mount  30 . 
     The heat transfer device  35  assumes an “overbite” relationship with the holder  14 , as shown in FIG.  3 . Namely, a cantilevered latch  40  on one edge of the heat sink mount  30  extends over and beyond the side  43  of the holder  14  side  15   a.    
     Referring to FIG. 7, the latch  40  is L-shaped and rests on a land  41  on a catch  42 . The side  43  of the catch  42  is offset from the surface  49  of the catch  42 , forming an effective land or stop  41 . Because the latch  40  extends outwardly past the surface  43 , the relationship between the heat transfer device  35  and the side  43  may be described as an overbite relationship. In addition, the engagement of the latch  40  horizontal portion  39  with the land  41  controls the extent of pivotal movement between the heat transfer device  35  and the holder  14 . This further aligns the horizontal portion  39  with the catch  42  defined within the holder  14 . 
     While an advantageous arrangement is shown in which the heat transfer device  35  pivots around a first side  15   b  of the holder  14  and latches on an opposed side  15   a  of the holder  14 , other arrangements may be possible as well. For example, an intermediate latching mechanism may also be used. 
     Referring again to FIG. 3, the heat transfer device  35  may then be translated in the direction indicated by the arrow A relative to the holder  14 . In the illustrated embodiment, the heat transfer device  35  is translated along a plane parallel to the circuit board  12 . It is translated in a direction that causes the latch  40  to move towards the pivot axle  46  (FIG. 5) and the catch  42  (FIG.  7 ). As a result, the arrangement of the axle  46  relative to the member  28  changes from that shown in FIG. 5 to that shown in FIG.  6 . That is, there is relative translating motion between the axle  46  within the slot  47  and the member  28 . 
     At the same time, this translation causes the latch  40  and its horizontal portion  39  to fully engage the catch  42  and to abut against the rear surface  51  of the catch  42 , as shown in FIG.  8 . In this situation, the latch  40  may also abut against the surface  41  in one embodiment of the present invention. Thus, the latch  40  has now engaged the catch  42 . However, the latch  40  is positioned at the bottom of the catch  42  relative to the heat transfer device  35 . 
     Referring next to FIG. 4, the heat transfer device  35  may be rotated in the direction indicated by the arrows B in accordance with one embodiment of the present invention. This may be done by rotating the active heat transfer device  36  and/or the heat sink  34  relative to the heat sink mount  30 . This rotation causes the heat sink member  38  to screw into the heat sink mount  30  and to extend further downwardly. The member  38  continues to thread downwardly, in response to the rotation indicated by the arrow B, until the heat sink member  38  comes into tight contact with the integrated circuit  22 . Thus, the heat transfer device  35  may be threaded into the heat sink mount  30 . 
     Upward motion of the heat transfer device  35  may be resisted by the engagement between the latch  40  and the catch  42 . More particularly, as shown in FIG. 9, the latch  40  moves upwardly relative to the catch  42 , in response to the rotation of heat transfer device  35 , until the horizontal portion  39  engages the upper edge  53  of the catch  42  in the holder  14 . In this position, the heat transfer device  35  is securely latched against motion relative to the holder  14 . The force of the heat sink member  38  against the integrated circuit  22  and particularly the die  24  provides an upward force which secures the latch  40  to the holder  14  in one embodiment of the invention. 
     Referring to FIG. 10, the heat transfer device  35  includes the active heat transfer device  36 , the heat sink  34  and the mount  30 . In one embodiment of the present invention, the active heat transfer device  36  and the heat sink  34  may be secured by threaded fasteners which engage the interstices between the upstanding pins  60  of the heat sink  34 . 
     The heat sink  34 , shown in FIG. 11, includes a base plate  62  from which the pins  60  extend. In addition, the centrally located, downwardly depending threaded member  38  is connected to the plate  62 . A wide variety of heat transfer devices may be used as the heat transfer device  35 . 
     The member  38  threadedly engages a ring  64  centrally located within the mount  30 . As a result, either or both of the active heat transfer device  36  and heat sink  34  may be rotated to cause the threaded member  38  to thread through the plate  30  and to engage the die  24 . 
     The heat transfer device  35  may be easily and accurately secured onto the integrated circuit  22  without the use of tools in some embodiments. Through a simple pivot, translate and rotate motion, the necessary connections may be securely and advantageously made. 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.

Technology Category: 5