Abstract:
An apparatus for adjoining along a mating axis a first and second circuit board to directly mate a first integrated connector of the first board with a second integrated connector of the second board is disclosed. The apparatus comprises an attachment plate to be supported in a substantially horizontal plane; a plurality of extension arms extending downward from the plate to suspendingly restrain the first board away from the plate; at least one stop configured to be secured to the distal end of one of the plurality of extension arms to support the first board in suspension away from the plate; and a plurality of attachment elements to secure the plate to the second circuit board without applying substantial forces to the first circuit board.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/653,400, entitled “Attachment Plate For Directly Mating Circuit Boards,” filed Nov. Sep. 2, 2003, which is hereby incorporated by reference herein. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to printed circuit boards and, more particularly, to an attachment plate for directly mating printed circuit boards.  
         [0004]     2. Related Art  
         [0005]     Computer systems have one or more printed circuit boards on which various digital and/or analog components are mounted. The principal printed circuit board in a computer system is generally referred to as a motherboard. In personal computers, the motherboard is often called the system board or mainboard. Typically, the motherboard holds many of the digital components integral to the functioning of a computer system such as the CPU, memory and basic controllers. In many instances, additional circuit boards may be attached to the motherboard to provide additional functionality. Such additional circuit boards include expansion boards and daughtercards (also referred to as daughterboards). Expansion boards are circuit boards that plug into a computer&#39;s expansion slots. Expansions boards include, for example, controller boards, LAN cards and video adapters.  
         [0006]     Daughtercards are typically attached directly to another printed circuit board such as the noted motherboard. In contrast to expansion boards, daughtercards access the motherboard components (memory and CPU) directly rather than through a slower expansion bus. Daughtercards typically include one or more integrated connectors, commonly referred to as a socket or header, which attach to an integrated connector on the motherboard. Once the integrated connectors are mated, the boards are typically joined by screws passing through holes in each circuit board.  
         [0007]     A mating force generated by tightening the aforementioned screws urges the circuit boards toward each other, and serves to establish and maintain the physical and electrical connection between the boards. To maintain the circuit boards in relatively parallel planes, a number of appropriately-distributed spacers are sometimes used. The height of the spacers is approximately the same as the combined height of both integrated connectors when those connectors are fully mated.  
         [0008]     Problems can arise when directly mating circuit boards such as the noted daughtercard and motherboard. If the force applied to the connectors during mating is not parallel to the pins and sockets of the connectors; for example, if the circuit boards are not maintained in parallel planes or laterally translate during mating, damage to the connector pins and sockets can easily result. One example of such a circumstance is when one or both of the circuit boards is not planar due to manufacturing imperfections, thermal cycling or other circumstances that can cause a printed circuit board to warp or curve. In this case, rotational or other non-axial forces can be placed on connector pins and sockets during mating. Under some circumstances, this can result in the bending of pins, incomplete electrical contact between some pins and their corresponding sockets, or other types of connection failures.  
       SUMMARY  
       [0009]     In one aspect of the invention, an apparatus for adjoining along a mating axis a first and second circuit board to directly mate a first integrated connector of the first board with a second integrated connector of the second board is disclosed. The apparatus comprises an attachment plate to be supported in a substantially horizontal plane; a plurality of extension arms extending downward from the plate to suspendingly restrain the first board away from the plate, wherein each extension arm comprises a recess at a distal end of the extension arm; at least one stop configured to be secured to the distal end of one of the plurality of extension arms to support the first board in suspension away from the plate, wherein the stop is configured to be secured using the recess of the extension arm; and a plurality of attachment elements to secure the plate to the second circuit board without applying substantial forces to the first circuit board.  
         [0010]     In another aspect of the invention, an apparatus for adjoining along a mating axis a first and second circuit board to directly mate a first integrated connector of the first board with a second integrated connector of the second board is disclosed. The apparatus comprises an attachment plate to be supported in a substantially horizontal plane; a plurality of extension arms extending downward from the plate to suspendingly restrain the first board away from the plate, wherein each extension arm is comprised of a smooth elongate shaft; at least one stop configured to be secured to the distal end of one of the plurality of extension arms to support the first board in suspension away from the plate, wherein the stop is configured to secure to the extension arm by applying an inwardly directed force on the extension arm; a pressure platform extending downward from the plate to apply to the first board a mating-axis force collocated with the first connector; and a plurality of attachment elements to secure the plate to the second circuit board without applying substantial forces to the first circuit board.  
         [0011]     In a further aspect of the invention, a method for adjoining along a mating axis a first and second circuit board to directly mate a first integrated connector of the first board with a second integrated connector of the second board is disclosed. The method comprises mounting the first circuit board on a plurality of extension arms extending from a first side of an attachment plate to suspend the first circuit board over the second circuit board with the first connector aligned with the second connector; securing at least one stop to a distal end of one of the plurality of extension arms to support the first board; and applying a mating force to a rear side of the first circuit board collocated with the first integrated connector to cause the first connector to mate with the second connector. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1A  is a perspective view of a conventional motherboard and daughtercard suitable for being used with the present invention.  
         [0013]      FIG. 1B  is a perspective view of the motherboard and daughtercard of  FIG. 1A  directly mated with each other.  
         [0014]      FIG. 2  is a perspective view of one embodiment of an attachment plate of the present invention, showing how the attachment plate is coupled to a daughtercard.  
         [0015]      FIG. 3  is a perspective view of one embodiment of the attachment plate shown in  FIG. 2 , showing how the attachment plate is used to connect the daughtercard shown in  FIG. 2  to a motherboard.  
         [0016]      FIGS. 4A-4C  are three cross-sectional views showing the mating of the daughtercard and motherboard of  FIG. 3 .  
         [0017]      FIG. 5  provides a perspective view of an embodiment of an attachment plate, showing how the attachment plate is coupled to a daughterboard.  
         [0018]      FIG. 6  illustrates an exemplary cap for use in some embodiments of the present invention.  
         [0019]      FIG. 7  illustrates an exemplary embodiment of a mated daughter card and motherboard using one embodiment of the caps illustrated in  FIG. 6 . 
     
    
     DETAILED DESCRIPTION  
       [0020]     The present invention is directed to an apparatus for facilitating the direct electrical connection between two printed circuit boards each having an integrated electrical connector.  FIGS. 1A and 1B  are perspective views of two printed circuit boards, a motherboard  102  and a daughtercard  106 . Motherboard  102  has an integrated electrical connector  104 A. Similarly, daughtercard  106  has an integrated connector or socket  104 B. Connectors  104 A and  104 B are corresponding halves of a conventional connector  104  such as ZIP socket, zero force insertion socket, and the like.  
         [0021]     When daughtercard  106  and motherboard  102  are mated, they are brought together along a mating axis  108  parallel with the longitudinal axis of the pins and receptacles of connector  104 , as shown in  FIG. 1B . A force substantially parallel with mating axis  108  (referred to as a mating axis force) is then applied to daughtercard  106  to urge the daughtercard toward motherboard  102 . Such mating axis forces cause the electrical and physical connection of the two integrated connectors  104 A,  104 B. Thereafter, daughtercard  106  is directly connected to motherboard  102 ; that is, connectors  104 A and  104 B are connected to each other with no intervening cables, wires or the like.  
         [0022]     As noted, when mating daughtercard  106  and motherboard  102 , rotational forces and translational forces that are not parallel to the mating axis (collectively referred to as non-mating axis forces) can damage connector pins or fracture traces or other electrical connections on the printed circuit boards  102 ,  106 , thereby reducing the reliability of the resulting assembly. For example, conventional daughtercards are typically mated directly to a motherboard with attachment screws located at the four corners of the daughtercard. Due to the lack of planarity of the daughtercard or the variability with which the attachment screws are adjusted, the applied mating forces can cause the printed circuit boards to bend, rotate, etc., causing stresses in the boards.  
         [0023]     Generally, the present invention is an attachment plate system that prevents non-mating axis forces from being applied to the integrated connectors of a mating motherboard and daughtercard. The invention physically suspends the daughtercard over the motherboard to allow the proper alignment of the integrated connectors to dictate the relative position of the printed circuit boards, and, preferably, to allow at least a partial mating of the connectors to occur before securing the printed circuit boards together. Any additional forces such as mating axis forces applied to further mate the connectors and/or to join the printed circuit boards, are applied solely to the attachment plate and not the suspended daughtercard. Such forces are transferred to a localized region of the suspended daughtercard immediately behind and collocated with the daughtercard&#39;s integrated connector, preventing the daughtercard from translating and rotating in response to such applied forces, other than to translate along the mating axis. Thus, variations in daughtercard tolerances, variability in operator mating technique, etc., do not cause internal stresses in the daughtercard which can damage the daughtercard connector, printed circuit board or components and connections on the printed circuit board.  
         [0024]     In the following description, embodiments of the attachment plate assembly will be described with reference to  FIGS. 2 and 3 . Then, use of the attachment plate assembly will be described with reference to the cross-sectional views of  FIGS. 4A through 4C .  FIGS. 2 and 3  are perspective views of one embodiment of an attachment plate assembly of the present invention. In  FIG. 2 , the attachment plate assembly is illustrated upside-down to show how the attachment plate system can receive a printed circuit board such as a daughtercard.  FIG. 3  is a perspective view of the attachment plate shown in  FIG. 2  rotated to mate the daughtercard suspended thereon to a motherboard.  
         [0025]     Generally, attachment plate assembly  200  comprises an attachment plate  202  configured to retain a daughtercard  250  with a rear side of the daughtercard facing attachment plate  202  and a top side of the daughtercard exposed for mating to a motherboard (not shown). In the embodiment shown in  FIGS. 2 and 3 , attachment plate  202  has a rear side  201  and a mating side  203  with a raised edge or sidewall  222  defining a shallow bay  204 . All components of attachment plate assembly  200  are coupled to attachment plate  202 .  
         [0026]     Integrated on mating surface  203  of attachment plate  202  are a plurality of extension arms  208  configured to restrain daughtercard  250  in a generally fixed position relative to attachment plate  202 , and to provide limited relative movement of daughtercard  250  substantially parallel to mating axis  108 . Mating axis  108  is parallel to the longitudinal axis of the pins and receptacles of connectors  254  and  302 , and travels through the center of the connectors. Daughtercard  250  includes holes  252  adapted to receive extension arms  208  as described below. In the orientation of attachment plate system  200  shown in  FIG. 2 , daughtercard  250  is placed on extension arms  208  causing each extension arm  208  to pass through a corresponding hole  252  in daughtercard  250 .  
         [0027]     It should be understood that extension arms  208  preferably have a diameter that allows for a close fit within daughtercard holes  252 . Such a close fit restricts rotation and lateral translation of daughtercard  250  relative to attachment plate  202 . After daughtercard  250  is mounted on extension arms  208 ,  0 -rings  218  are attached to the extension arms as shown in  FIG. 2 . When attachment plate  202  is rotated into the proper orientation to mate daughtercard  250  with a motherboard, as shown in  FIG. 3 , daughtercard  250  will shift away from attachment plate  202  to come to rest against o-rings  218  in a position on extension arms  208  suspended away from attachment plate  202 . This is described in detail below.  
         [0028]     A raised pressure plate  206  is provided on mating side  203  of attachment plate  202 . In one preferred embodiment pressure plate  206  has approximately the same cross-sectional area and, more preferably, approximately the same cross-sectional dimensions as connector  254 .  
         [0029]     Pressure plate  206  is centered on mating axis  108  to be collocated with connector  254  when daughtercard  250  is mounted on attachment plate  202 . Importantly, pressure plate  206  is the forward-most contacting surface on attachment plate  202 . As such, pressure plate  250  is the only portion of attachment plate  202  that applies a force to daughtercard  250  when attachment plate  202  is secured to motherboard  300  (shown in  FIG. 3 ). More specifically and as will be described in detail below, attachment plate  202  transfers mating forces applied to attachment plate  202  to pressure plate  206  which in turn transfers the applied mating forces to the rear side of daughtercard  250  behind connector  254 . Because pressure platform  206  has approximately the same cross-sectional area as connector  254 , the applied mating forces are distributed evenly across the connector.  
         [0030]     Attachment plate  202  has a plurality of attachment screw/spring assemblies  210  for securing the attachment plate directly or indirectly to the motherboard. Attachment screw/spring assemblies  210  include an attachment screw  212  surrounded by an attachment spring  214 . As is well know in the art, motherboard  300  includes corresponding threaded holes  302  for receiving screws such as attachment screws  212 . Alternatively, motherboard  300  can be mounted on a plate or other support structure that includes such corresponding threaded holes  302 .  
         [0031]     Attachment screw/spring assemblies  210  are distributed around daughtercard  250  and oriented parallel to mating axis  108 . When connector  254  is aligned with an integrated connector  304  on motherboard  300 , attachment screws  212  are aligned with a corresponding threaded hole  302  in the motherboard. Preferably, attachment screw/spring assemblies  210  are symmetrically distributed around connector  254 . In the illustrated embodiment, four attachment screw/spring assemblies  210  are shown located at each of the four corners of attachment plate  202 .  
         [0032]     As shown in  FIGS. 2 and 3 , attachment screw/spring assemblies  210  are positioned on rear side  201  of attachment plate  202 , with each attachment screw  212  extending through a hole in the attachment plate. Springs  214  are compressed between attachment plate  202  and the head of a corresponding attachment screw  212 . Spring  214  of each attachment screw/spring assembly  210  provides a biasing force on its associated screw  212  to urge screw  212  toward an unengaged position; that is, to prevent it from falling through attachment plate  202  when the plate is rotated into the mating orientation shown in  FIG. 3 . Each attachment screw/spring assembly  210  is coupled to attachment plate  202  by a snap ring or c-clip  213  on mating side  203  of attachment plate  202 . Each screw  212  has an undercut (not shown) that operates with snap ring  213  to prevent screw  212  falling from attachment plate  202  when the plate is in the position shown in  FIG. 2 . In contrast to conventional attachment screws which apply mating forces directly to the daughtercard, attachment screws  212  apply a mating axis force to attachment plate  202  which translates the mating forces to connector  254  via pressure plate  206 , as noted above and described in detail below. Because daughtercard  250  is not in contact with attachment plate  202  at the vicinity of attachment screws  212 , and because the attachment screws are coupled to the plate rather the daughtercard, the mating forces applied by the attachment screws cannot cause any tolerance stack on any of the four corners of the daughtercard.  
         [0033]     The operation of the illustrative embodiment of attachment plate system  200  will now be described with reference to  FIGS. 4A-4C .  FIGS. 4A-4C  are three cross-sectional views of daughtercard  250  and motherboard  300 .  FIG. 4A  shows the two printed circuit boards as they are initially brought into contact with each other.  FIG. 4B  shows the two connectors  254 ,  302  partially mated, for example, under the weight of daughtercard  250 .  FIG. 4C  shows the two connectors  254 ,  302  fully mated in response to a mating force applied through attachment plate  202 . It should be understood that in the cross-sectional views illustrated in  FIGS. 4A-4C  attachment plate assembly  200  is oriented as shown in  FIG. 3 ; that is, in the “mating” orientation. It should also be appreciated that in  FIGS. 4A-4C  only certain portions of attachment plate assembly  200  are illustrated; primarily, pressure platform  206 , extension arms  208  and attachment screw/spring assembly  210 , as defined by section line “FIGS.  4 A-C” shown in  FIG. 2 .  
         [0034]     Referring now to  FIG. 4A , the relevant dimensions of these particular components is first described. In operation, after daughtercard  250  is mounted on attachment plate  202 , the attachment plate is turned over as shown in  FIG. 3 , and daughtercard connector  254  is aligned with motherboard connector  304 . The position of daughtercard  250  on attachment plate  202  when oriented for mating is shown in  FIG. 4A . As shown there, when rotated, daughtercard  250  travels downward on extension arms  208  to rest on compliant stops  216 . In this position, there is a gap between pressure platform  206  and daughtercard  250 .  
         [0035]     In one embodiment, extension arms  208  are formed with a standoff  404  defined by a larger diameter than an upper post  406  of the extension arms. Upper post  406  has a recessed  205  for receiving compliant stop  216 . Standoff  404  has a height  408  that is less than height  410  of pressure plate  206 . Upper post  406  is comprises of post regions  406 A and  406 B with recess  205  interposed between the two post regions  406 . Post regions  406 A and  406 B have a diameter that is no larger than the diameter of daughtercard hole  252 . Preferably, at least lower post region  406 A has a diameter that allows for a close fit within hole  252  to provide positional stability of daughtercard  250  with respect to attachment plate  200  to prevent rotation and lateral translation of the daughtercard when it is engaged with lower post  406 A.  
         [0036]     Recess  205  accepts an correspondingly configured o-ring  216 . Preferably, the diameter of o-ring  216 , upper post  406 B and recess  205  have relative dimensions that requires o-ring  216  to be slightly expanded to slide or roll over post region  406 B until o-ring  216  reaches recess  205 . Recess  205  allows o-ring  216  to contract to a smaller diameter to securely fit within the recess. The outside diameter of o-ring  216  is greater than the diameter of hole  252 , enabling o-ring  216  to provide a support surface for the suspended daughtercard  250 . It should be appreciated that other compliant and non-compliant stops other than o-ring  216  can be used. Preferably, such stops do not require the use of additional tools. However, a person of ordinarily skill in the art will recognize that a variety of different retaining hardware such as a c-clip, snap ring, or cap can be used to facilitate the function of stop  216 .  
         [0037]     The height  412  of lower post region  406 A is greater than thickness  410  of daughtercard  250 . When daughtercard  250  rests against o-ring  216 , there is a gap  414  between the daughtercard and the post standoff  404 . Gap  414  is greater than gap  416  between pressure plate  206  and daughtercard  250 , as shown in  FIG. 4A . When suspended in this position, daughtercard  250  is held in a generally fixed position relative to attachment plate  202  with limited movement parallel to mating axis  108 . That is, daughtercard  250  is free to move along mating axis  108  on extension arms  208 , while movement along other axes and rotation with respect to attachment plate  202  is restricted. Distance  416  defines the amount of limited axial movement of daughtercard  250 . In one embodiment, distance  416  is approximately 0.4 mm. In the illustrative embodiment, the combination of distance  416  and the resilience of o-ring  216  provides daughtercard  250  with the capability of traveling up to 0.8 mm along mating axis  108 . It should be apparent to those of ordinary skill in the art that other distances can be implemented in other embodiments.  
         [0038]     The operation of mating daughtercard  250  and motherboard  300  will now be described with reference to  FIGS. 4A-4C . As noted,  FIG. 4A  shows the two printed circuit boards  250 ,  300  as they are initially brought into contact with each other. As shown in  FIG. 4A , connector halves  254 ,  304  are the first surfaces to contact each other. Height  418  of extension arm  208  and height  420  of attachment screw housing  226  are such that neither element contacts motherboard  300  prior to connector  254  contacting connector  304 . Thus, connectors  254 ,  304  are first aligned with each other in the absence of an influence of other elements of attachment plate  202  and daughtercard  250  coming into contact with motherboard  300 .  
         [0039]     In addition, as noted above, attachment springs  214  are compressed and interposed between the head of screws  212  and attachment plate  202  to bias attachment screws  212  toward an unengaged position. By biasing attachment screws  212  away from their attachment position, the attachment screws are prevented from extending toward and contacting motherboard  300  before the mating of connectors  254 ,  304 . Thus, the alignment between the printed circuit boards  250 ,  300  and connectors  254 ,  304  is dictated solely by the connectors, not the initial engagement of attachment screws  212 .  
         [0040]     Referring now to  FIG. 4B , attachment plate  202  has been lowered further from the position shown in  FIG. 4A . In the particular embodiment shown, connectors  254 ,  302  have partially mated, for example, under the weight of daughtercard  250 . It should be appreciated that connectors  254 ,  304  may or may not partially or completely mate under the weight of daughtercard  250  depending on the weight of the card and the type of connectors.  
         [0041]     As attachment plate assembly  200  is lowered, extension arm  208  travels through opening  252  until pressure plate  206  encounters the rear side of daughtercard  250 .  
         [0042]     Subsequent to some initial potential mating, daughtercard  250  is no longer supported by stops  216 ; rather, the daughtercard is supported by the resistance of connectors  254 ,  304  to further mating. In the illustration of  FIG. 4B , attachment plate  202  has been lowered until pressure platform  206  has made initial contact with the rear side of printed circuit board  250 .  
         [0043]     Further mating of daughtercard  250  and motherboard  300  occurs in response to securing attachment plate  202  to motherboard  300 . In  FIG. 4C , attachment plate  202  is secured to motherboard  300  via attachment screws  212 . As noted, attachment screws  212  are one component of attachment screw/spring assemblies  210 . To cause attachment screws  212  to engage threaded holes  302  in motherboard  300 , a manual force parallel to mating axis  108  is applied to the head of attachment screw  212 , such as with a screwdriver. The applied force causes springs  214  to compress and attachment screw  212  to extend toward motherboard  300 . Rotation of attachment screw  212  causes the screw to further engage threaded hole  302 , causing the further mating of connectors  254 ,  304 . As attachment screws  212  are each rotated, they apply a mating force to attachment plate  202 . Since the only portion of attachment plate  200  that is in contact with daughtercard  250  is pressure platform  206  collocated with connector  254 , and not extension arms  208  at the corners of daughtercard  250 , all such applied mating forces are applied to daughtercard  250  through pressure platform  206 . This internal attachment of daughtercard  250  to pressure platform  206  prevents variations in the threading of attachment screws  212  and variations in the planarity of daughtercard  250  from causing rotational or other non-mating axis forces to be applied to connectors  254 ,  304 .  
         [0044]     Once daughtercard  250  and motherboard  300  are mated, and attachment plate  202  is attached to motherboard  300 , the two circuit cards are maintained in a stable relative position by attachment screw/spring assembly  210 . Compressed springs  214  and the threaded mating of screws  212  and motherboard  300  maintain daughtercard  250  and motherboard  300  in a fixed relative position. This maintains the integrity of the electrical connection between connectors  254 ,  304  when the circuit cards  250 ,  300  undergo thermal expansion and compression cycles during the operational life of the mated components. Oftentimes the components and connectors expand and contract at different rates and to different extents. Such thermal cycles can cause unintended fracturing or separation adversely affecting the reliability of the electrical connection between such components.  
         [0045]     As discussed above in the embodiment illustrated in  FIG. 2 , recess  205  allows o-ring  216  to contract to a smaller diameter to securely fit within the recess. In this and other embodiments, the depth of recess  205  may vary. For example, recess  205  may be very deep relative to the thickness of o-ring  216  or recess  205  may be very shallow. Or, in other embodiments, extension arms  208  may not include a recess. A deep recess  205  may be used in situations where it is desirable for o-ring  216 , or other retaining hardware (e.g., c-clip, snap ring, or cap) to more securely attach to extension arm  208 . A shallow recess, however, may be used in situations where it is desirable for o-ring  216  or other retaining hardware to more easily slide off of extension arm  208 . O-rings  216  (or other retaining hardware) may, for example, be manufactured using any suitable materials, such as, for example, a plastic, such as, a neoprene, polypropylene, a polycarbonate, a polycarbonate blend, etc.  
         [0046]      FIG. 5  provides a perspective view of an embodiment of an attachment plate, showing how the attachment plate is coupled to a daughtercard.  FIG. 5  is identical to  FIG. 2  with the exception that in this embodiment, extension arms  208  do not include a recess, but instead have a smooth surface. An embodiment, such as illustrated in  FIG. 5  may be used in situations where, for example, it is desirable for o-rings  216  to be removed after mating of the daughterboard and motherboard. By using smooth extension arms  208 , o-rings  216  may be more easily detached.  
         [0047]     In embodiment such as illustrated in  FIG. 5 , o-ring  216  or other suitable retaining hardware may have an interior diameter slightly smaller than the diameter of extension arm  208 . O-ring  216  may then be attached to the extension arm by slightly expanding o-ring  216  and sliding it over extension arm  208 . O-ring  216  may then contract and exert an inwardly-directed force on extension arm  208  to secure the o-ring in place. In such an embodiment, o-ring  216  may have various interior diameters and be made of various materials to ensure that a desirable inward force is applied. For example, where a more secure attachment is desirable (i.e., a greater inward force), o-ring  216  may have a smaller diameter and/or be made of a material having a stronger elasticity. Or, where it is desirable to have an o-ring  216  that can more easily slide off/on extension arm  208 , o-ring  216  may have a larger diameter and/or be manufactured with a material having a lower modulus of elasticity. For example, it may be desirable in certain embodiments to remove attachment plate  202  after mating of the daughtercard  250  to the motherboard  300 . In such an embodiment, after mating, attachment plate  202  may be removed by, for example, unscrewing attachment screws  212  and lifting up on attachment plate  202  causing o-rings  206  to slide off extension arms  208 . In such an embodiment, o-rings  206  preferably have a diameter and elasticity that allows them to easily slide off extension arms  208  so that connectors  254  and  304  remain mated after removal of attachment plate  202 .  
         [0048]     In alternative embodiments, retaining hardware or “stops” other than -o-rings may be used. For example, in one embodiment retaining hardware such as, for example, c-clips, snap rings, or caps are utilized to suspend daughtercard  250  on extension arms  208 .  FIG. 6  illustrates an exemplary cap for use in certain embodiments of the present invention.  FIG. 7  illustrates an exemplary embodiment of a mated daughtercard  250  and motherboard  300  using caps  602 . The view shown in  FIG. 6  is taken along the section line illustrated in  FIG. 7 .  
         [0049]     As illustrated, cap  602  may be secured to the distal end of extension arm  208 . A protrusion  604  on the interior surface of cap  602  may traverse at least a portion, and preferably the entire circumference of the interior cavity of cap  602  such that when slid over extension arm  208 , ridge  604  fits into recess  205  of extension arm  208  to secure cap  602  to extension arm  208 . Cap  602  may be made of any suitable material, such as, for example, a plastic. This plastic may be formed from any appropriate material such as, for example, a neoprene, polypropylene, a polycarbonate and/or a polycarbonate blend. Further, for example, cap  602  material may be such that when slid over extension arm  208 , the interior cavity of cap  602  is expanded, such that when ridge  604  slides over recess  205 , cap  602  may contract to a smaller diameter such that ridge  604  securely fits in recess  205 . The height  608  of cap  602  may also vary for different embodiments.  
         [0050]      FIG. 7  illustrates an exemplary embodiment of a mated daughtercard  250  and motherboard  300  using caps  602 .  FIG. 7  is identical to previously discussed  FIG. 4C  with the exception that caps  602  are utilized to perform two functions: to suspendingly retain daughtercard  250  on extension arms  208 , and to serve as a spacer to prevent mating forces generated by attachment screws  212  from flexing motherboard  300  toward attachment plate  202  or from twisting motherboard  300  so as to adversely affect the physical and electrical connection between daughtercard  250  and motherboard  300 . In the embodiment shown in  FIG. 7 , caps  602  serve as spacers between daughtercard  250  and motherboard  300 , as described below. When cap  602  is secured to extension arm  208  the combined length of the cap and extension arm is approximately the same as the combined thickness or height of integrated connectors  254 ,  304 , pressure plate  206  and daughtercard  250  when connectors  354 ,  304  are fully mated.  
         [0051]     As shown, cap  602  is fitted over post region  406 B of extension arm  208 . The uppermost post regions  406 A and  406 B (and recess  205  located therebetween) of extension arm  208  are illustrated as a dotted lines because when cap  602  is fitted over extension arm  208 , these portions of extension arm  208  are located within the interior cavity of cap  602 . Further, in this embodiment, cap  602  has a height such that when installed on extension arm  208  and daughtercard  250  is mated with motherboard  300 , cap  602  contacts motherboard  300 . That is, cap  602  has a height such that it fills up the gap between daughtercard  250  and motherboard  300  when their respective connectors  254 ,  304  are fully mated.  
         [0052]     As noted, when cap  602  is secured to extension arm  208  the combined length of the cap and extension arm is approximately the same as the combined thickness or height of integrated connectors  254 ,  304 , pressure plate  206  and daughtercard  250  when connectors  354 ,  304  are fully mated. Should attachment screws  212  be over tightened (or other forces are exerted on motherboard  300 ), the capped extension arms  202  may help support some of this force to relieve excess forces being applied to motherboard  300  and connectors  254  and  304 .  
         [0053]     In certain embodiments, cap  602  may also be manufactured so that after mating of daugthercard  250  and motherboard  300 , the height  608  of cap  602  is such that the cap is in contact with motherboard  300  and daughtercard  250 . In such an embodiment, cap  602  may also help relieve mating axis forces applied to daughtercard  250 .  
         [0054]     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. For example, pressure platform  206  can be fabricated as part of attachment plate  202  or it may be subsequently attached to the plate  202  after the attachment plate is fabricated. The ability to attach pressure platform  206  to attachment plate  202  after the attachment plate is fabricated allows the user to interchange various size pressure platforms to correspond to various size connectors  254 . As another example, in the embodiment of attachment plate assembly  200  described above, attachment plate  202  includes a sidewall  222  that defines a shallow bay  204 . It should be appreciated, however, that such a sidewall is not necessary. In alternative embodiments, for example, attachment plate  200  does not include such a sidewall. As a further example, in the embodiment illustrated in  FIG. 2 , three extension arms  208  and two o-rings  218  are used to suspendingly secure daughter card  250  to attachment plate  202 . However as one of ordinary skill in the art will find apparent, in alternative embodiments different quantities and combinations of extension arms  208  and o-rings  218  can be implemented. As a further example, in an alternative embodiment, apertures  228  are threaded to retain screws  212  in attachment plate  202 , eliminating the need for springs  214  and clips  216  while requiring rotations of screws  212  to bring screws  212  into engagement with threaded holes  302  on motherboard  300 . Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.