Abstract:
A mechanical set of plates is able to simultaneously and quickly removably secure and remove one or more printed circuit boards (PCBs) in an enclosure in one single motion, and act as a heat sink to conduct heat away from the PCBs. The PCBs are removably secured through a clamping mechanism that may be a screw type or cam lever action by clamping down on the exposed card edges, thus allowing thermal transfer to begin on all cards. The apparatus may be used with any enclosure requiring thermal transfer from PCBs to the enclosure, including cages and enclosures that may or may not use forced airflow (fans or blowers) for heat dissipation.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    As integrated circuit technology has improved, substantially greater functionality has been incorporated into devices. Along with this expanded functionality, the size of devices has diminished resulting in higher clocking frequencies and increased power consumption. As a consequence, the integrated circuit devices of today generate more heat while possessing smaller surface areas to dissipate the heat. Therefore, it is important to have a high rate of heat transfer from the integrated circuit package to maintain the temperature of the integrated circuit within safe operating limits. Excessive heat may adversely affect the performance of the circuit, cause permanent degradation of its components and increase failure rates. 
         [0002]    A heat exchange with a heat sink may be used for transferring heat away from a heat source, such as an electronic component or printed circuit board (PCB), to maintain the component within an optimum operating temperature range, so that the component can operate continuously and with maximized efficiency. Often, the heat sink used is a special plate, called a cold plate, that contains slots for holding individual PCBs. The PCBs are held in place by a retainer, which is generally a thermally conductive metal block that is fastened along the PCB to create a point of thermal conduction with the cold plate. The retainer, along with the PCB, is placed into a slot of the cold plate. 
         [0003]    Prior art, such as U.S. Pat. No. 4,819,713 to Weisman, provides a retainer for holding a single card in the slots of a cold plate with a rail mounted to either the module or the holder and wedge shaped bodies to be slid over the rail, attaching the rail to the cold plate, thereby providing a surface for thermal conduction. However, these devices are expensive, require an enclosure to be designed specifically to accommodate the retainer and mandate that the retainer is fixed per manufacturer instructions, which may not work for all enclosure designs. Further, if multiple cards are present, each card must be individually unfastened before removal from the enclosure, which is a time-consuming and cumbersome process that may involve numerous screws, washers and other pieces. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention addresses the foregoing shortcoming or problems of the prior art. The invention apparatus is a set of mechanical plates acting as an enclosure&#39;s card guides. It may be able to clamp one or more cards in place that are in the enclosure all at the same time through the use of a solid, heavy cast or machined base guide plate and a sliding secondary plate. 
         [0005]    An embodiment of the present invention is an apparatus and corresponding method for removably securing one or more electronic modules in a holder. A stationary guide plate and a movable guide plate form a plurality of channels to guide one or more electronic modules into position in the holder. A clamping mechanism repositions the movable guide plate such that the widths of the plurality of channels may be substantially simultaneously increased or decreased. 
         [0006]    The adjustment of the movable guide plate may be from a minimum position (width) to a maximum, the maximum widths being 0.010 inches (0.254 mm) to 0.020 inches (0.508 mm) greater than the widths of the one or more electronic modules. The adjustment of the movable guide plate&#39;s position toward its minimum position decreases the width of the channel created by the surfaces of the movable guide plate and the stationary guide plate and may cause these surfaces to press against both sides of the one or more electronic modules inserted into the channels. 
         [0007]    Two instances of the apparatus may be placed inside the holder; a first instance on the top inside surface of the holder and a second instance, a mirror-image of the first instance, on the bottom inside surface of the holder. Each of these instances removably secures an edge (or end) of the one or more electronic modules inserted into the channels. A clamping mechanism operates the movable guide plate of both instances of the apparatus at the same time and may be a screw or cam lever, for example. Alternatively, there may be two clamping mechanisms that independently operate the guide plates of each instance of the apparatus. 
         [0008]    The clamping mechanism, stationary guide plates and movable guide plates may thermally conduct heat to the holder from the one or more electronic modules. The holder may be any enclosure requiring thermal transfer from one or more electronic modules to the holder. The one or more electronic modules may be PCBs. The plurality of channels may also guide the one or more electronic modules into position in the holder in alignment with a backplane connector. 
         [0009]    Additionally, securing PCBs in such a way eliminates costly retaining hardware normally used to ensure that seated cards do not vibrate out of position or pull out during shipment or vibration testing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. 
           [0011]      FIGS. 1A-1B  are cross-sectional view illustrating the movable guide plate and stationary guide plate with four card guides, in relation to the surface of the enclosure, in an unclamped and clamped position, respectively. 
           [0012]      FIG. 2  is a cross-sectional view illustrating two instances of the fixed and movable guide plates in the enclosure, a card and the clamping mechanism. 
           [0013]      FIGS. 3A and 3B  are diagrams illustrating multiple enclosures mounted in a rack and ruggedized case, respectively. 
           [0014]      FIG. 4A  is a perspective view illustrating an example embodiment of the clamping mechanism using a screw. 
           [0015]      FIG. 4B  is a perspective view illustrating an example embodiment of the clamping mechanism using a cam lever. 
           [0016]      FIGS. 5A-5C  are perspective views illustrating an example embodiment of a movable guide plate alone, a stationary guide plate alone and a movable and a stationary guide plate together, respectively. 
           [0017]      FIGS. 6A-6C  are perspective views illustrating another example embodiment of a movable guide plate alone, a stationary guide plate alone and a movable and a stationary guide plate together, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    A description of example embodiments of the invention follows. 
         [0019]      FIG. 1A  is a cross-sectional view illustrating the movable guide plate  105  and stationary guide plate  110  with four card guides  130 , in relation to the surface of enclosure  100 , in an unclamped position. It will be understood by one skilled in the art that a card guide  130  is a channel that guides each card  115  into position and in alignment to a backplane connector (not shown) that may be present that it mates to. The movable guide plate  105  makes up the left side of each card guide  130 . The stationary guide plate  110  makes up the right side of each card guide  130 . In this unclamped position, the width of the card guide  130  is greater than the thickness of the card  115 . This nominal gap  125  allows the card  115  to slide freely into position in the card guide  130 . The gap  125  may be to the left or right of the card  115 , or a portion of the gap  125  may be to one side of the card  115  while the remainder of the gap  125  is to the other side of the card  115 . 
         [0020]      FIG. 1B  is a cross-sectional view illustrating the movable guide plate  105  and stationary guide plate  110  with four card guides  130 , in relation to the surface of the enclosure  100 , in a clamped position. As in  FIG. 1A , the movable guide plate  105  makes up the left side of each card guide  130  and the stationary guide plate  110  makes up the right side of each card guide  130 . However, with the movable guide plate  105  in a clamped position there is no nominal gap  125  as in  FIG. 1A . By repositioning the movable guide plate  105  to the right (toward the cooperating stationary guide plate  110 ), the nominal gap, previously present when the movable guide plate  105  was in an unclamped position, is removed. This repositioning causes the movable guide plate  105  to press against the left face of the card  115  and the stationary guide plate  110  to press against the right face of the PCB  115 . It is by this contact between the movable guide plate  105  and stationary guide plate  110  with the card  115  that allows heat to be conducted from the card  115  to the movable guide plate  105 , stationary guide plate  110 , clamping mechanism (not shown) and enclosure  100 . 
         [0021]      FIG. 2  is a cross-sectional view illustrating two instances  205   a ,  205   b  of the movable guide plate  105   a ,  105   b  and stationary guide plate  110   a ,  110   b  in relation to two surfaces  100   a ,  100   b  of the enclosure  100 , a card  115  and the clamping mechanism  200 . In this example embodiment, a first instance  205   a  of the movable guide plate  105   a  and stationary guide plate  110   a  is placed on the bottom face  100   a  of the inside of the enclosure  100 . A second instance  205   b  of the movable guide plate  105   b  and stationary guide plate  110   b  is a mirror image of the first instance  205   a  and is placed on the top face  100   b  of the inside of the enclosure  100 . A card  115  may then be inserted into one of the card guides  130 . The first instance  205   a  removably secures the bottom end or edge of the card  115  while the second instance  205   b  removably secures the top end or edge of the card  115 . In this way, the first and second instances  205   a ,  205   b  cooperate with each other to removably secure opposite ends of cards  115 , each in respective channels (card guides  130 ). 
         [0022]    Once all cards  115  that are to be inserted (in this example embodiment, up to and including four cards, one per channel) into the enclosure  100  are in place and seated into their respective backplane connectors (not shown) they can be removably secured in place with a sliding action. This sliding action repositions both movable guide plates  105   a ,  105   b  simultaneously to eliminate the gaps  125  across all card guides  130 . Using a single motion, the clamping mechanism  200 , which may be a screw or cam lever action design, repositions the movable guide plates  105   a ,  105   b  such that the movable guide plates  105   a ,  105   b  and stationary guide plates  110   a ,  110   b  clamp down on all cards  115  at the same time. With the cards  115  removably secured in place, the cards  115  are squeezed through the contact with the movable guide plates  105   a ,  105   b  and stationary guide plates  110   a ,  110   b  such that thermal transfer may take place from the cards  115 , through the movable guide plates  105   a ,  105   b , stationary guide plates  110   a ,  110   b  and clamping mechanism  200  to the enclosure  100 . 
         [0023]    When removal of cards  115  from the enclosure  100  is required, the clamping mechanism  200  is released, also in a single motion, simultaneously removing the clamping force from all inserted cards  115 . In a manner similar to, but opposite of, that described above, using a single motion, the clamping mechanism  200 , which may be a screw or cam lever action design, repositions the movable guide plates  105   a ,  105   b  such that the movable guide plates  105   a ,  105   b  and stationary guide plates  110   a ,  110   b  no longer clamp down on all cards  115 . This sliding action repositions both movable guide plates  105   a ,  105   b  so that gaps  125  are created. The cards  115  may now be freely unseated from their respective backplane connectors (not shown) and removed from the enclosure  100 . 
         [0024]      FIGS. 3A and 3B  are diagrams illustrating multiple enclosures  100  mounted in a rack  305  and a ruggedized case  310 , respectively. 
         [0025]      FIG. 4A  is a perspective view illustrating an example embodiment  400   a  of the clamping mechanism  200  using a screw. In this example embodiment  400   a , a screw  405   a  is threaded through the enclosure  100 . The distal end of the screw  405   a  is attached to the connector  210  portion of the clamping mechanism which connects to the two movable guide plates (not shown). The screw  405   a  is attached to the connector  210  in such a way that the attached end is able to rotate freely as the screw  405   a  is threaded through the enclosure  100 . The threading action and unthreading action of the screw  405   a  through the enclosure  100  causes the connector  210  to be moved in either direction along the axis of the screw  405   a  so that the connected movable guide plates  105   a ,  105   b  (shown in  FIG. 2 ) are repositioned. As described above with reference to  FIG. 2 , repositioning of the guide plates  105   a ,  105   b  such that they clamp down on the cards  115  removably secures them in place and allows thermal conduction. 
         [0026]      FIG. 4B  is a perspective view illustrating an example embodiment  400   b  of the clamping mechanism  200  using a cam lever. In this example embodiment  400   b , a cam lever  405   b  is attached to the enclosure  100 . The end of the piston  410  of the cam lever  405   b  is attached to the connector  210  portion of the clamping mechanism that connects to the two movable guide plates (shown in  FIG. 2 ). The cam lever  405   b  is attached to the enclosure  100  and connector  210  in such a way that raising and lowering the handle  407  causes the piston  410  to be extended and retracted, thereby causing the connector  210  to be moved in either direction along the axis of the piston  410  so that the connected movable guide plates  105   a ,  105   b  (not shown) are repositioned. As described above with reference to  FIG. 2 , repositioning of the guide plates  105   a ,  105   b  such that they clamp down on the cards  115  removably secures them in place and allows thermal conduction. 
         [0027]      FIGS. 5A-5C  are perspective views illustrating an example embodiment of a movable guide plate  105  alone, a stationary guide plate  110  alone and a movable  105  and a stationary  110  guide plate together, respectively. 
         [0028]      FIG. 5A  is a perspective view illustrating an example embodiment of a movable guide plate  105  having a base  505   a  and four risers  515   a . The risers  515   a  are the portion of the movable guide plate  105  that comes in contact with the cards  115  to removably secure them in place and allow thermal conduction. 
         [0029]      FIG. 5B  is a perspective view illustrating an example embodiment of a stationary guide plate  110  having a base  505   b , four risers  515   b  and four openings  510 , one for each riser  515   b . The risers  515   b  are the portion of the stationary guide plate  110  that come in contact with the cards  115  to removably secure them in place and allow thermal conduction. The openings  510  allow the risers  515   a  of the movable guide plate  105  to pass through the base  505   b  of the stationary guide plate  110  to align with the risers  515   b  of the stationary guide plate  110  to create the card guides  130  in  FIG. 2 . 
         [0030]      FIG. 5C  is a perspective view illustrating an example embodiment formed of the movable guide plate  105  of  FIG. 5A  and the stationary guide plate  110  of  FIG. 5B . The stationary guide plate  110  is positioned on top of the movable guide plate  105  so that, through the underside of the base  505   b  of the stationary guide plate  110 , the four risers  515   a  of the movable guide plate  105  are aligned with and pass through the four openings  510  in the stationary guide plate  110 . This results in the four risers  515   a  of the movable guide plate  105  being paired with and aligned with the four risers  515   b  of the stationary guide plate  110 . The associated riser pairs  515   a ,  515   b  make each card guide  130 , illustrated in  FIG. 1A . The guide plates  105 ,  110  may then be operated as described above with reference to  FIG. 2 . 
         [0031]      FIGS. 6A-6C  are perspective views illustrating an example embodiment of a movable guide plate  105  alone, a stationary guide plate  110  alone and a movable  105  and a stationary  110  guide plate together, respectively. 
         [0032]      FIG. 6A  is a perspective view illustrating an example embodiment of a movable guide plate  105  having a base  605   a , four fingers  610   a  and four risers  615   a . The risers  615   a  are the portion of the movable guide plate  105  that comes in contact with the cards  115  to removably secure them in place and allow thermal conduction. The four fingers  610   a  are evenly spaced  612  and allow the movable guide plate  105  and stationary guide plate  110  to be fit together to create card guides  130  with the risers  615   a ,  615   b.    
         [0033]      FIG. 6B  is a perspective view illustrating an example embodiment formed of a stationary guide plate  110  having a base  605   b , four fingers  610   b  and four risers  615   b . The risers  615   b  are the portion of the stationary guide plate  110  that comes in contact with the cards  115  to removably secure them in place and allow thermal conduction. The four fingers  610   b  are evenly spaced  612 , the spacing being equal to that of the fingers  610   a  of the movable guide plate  105 , and allow the movable guide plate  105  and stationary guide plate  110  to be fit together to create card guides  130  with the risers  615   a ,  615   b . Further, the stationary guide plate  110  is a duplicate of the movable guide plate  105  of  FIG. 6A  except that it is rotated 180 degrees on the horizontal plane. This provides certain manufacturing and assembly advantages. 
         [0034]      FIG. 6C  is a perspective view illustrating an example embodiment of the movable guide plate  105  of  FIG. 6A  and the stationary guide plate  110  of  FIG. 6B . The movable guide plate  105  and stationary guide plate  110  are positioned in such a way that their respective fingers  610   a ,  610   b  are juxtaposed and interlocked. The width of the fingers  610   a ,  610   b  is less than the even spacing  612  between the fingers such that gaps  613  remain between the associated pairs of fingers  610   a ,  610   b  so that the movable guide plate&#39;s fingers  610   a  can be repositioned. The associated riser pairs  615   a ,  615   b  make each card guide  130  as illustrated in  FIG. 1A . The guide plates  105 ,  110  may then be operated as described above with reference to  FIG. 2 . 
         [0035]    While this invention has been particularly shown and described with references to example be made therein without departing from the scope of the embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may invention encompassed by the appended claims.