Abstract:
A method and apparatus for aligning a connector between a printed wiring board and a mezzanine board includes mounting the printed wiring board to a frame, locating a cover with respect to the frame by way of a first pin and a second pin, fastening the cover to the frame, locating the mezzanine board with respect to the cover by way of a third pin and a fourth pin, and fastening the mezzanine board to the cover.

Description:
RELATED APPLICATION DATA 
       [0001]    This application claims benefit under 35 U.S.C. Section 119(e) of co-pending U.S. Provisional Application No. 60/930,613 filed May 17, 2007, which is fully incorporated herein by reference. 
     
    
     GOVERNMENT LICENSE RIGHTS 
       [0002]    The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Contract Number Q7V223 awarded by the U.S. Air Force. 
     
    
     BACKGROUND 
       [0003]    The present invention relates to printed wiring board assemblies, and more particularly, to printed wiring board assemblies having mezzanine boards. 
         [0004]    Printed wiring board assemblies often include a main printed wiring board, sometimes referred to as a motherboard, and a mezzanine card or mezzanine board that connects to the main printed wiring board. Often, the mezzanine card connects to the main printed wiring board using pin-type connectors or plug/receptacle combinations. Each connector may have 32, 64 or more fragile plugs or pins. The mezzanine card typically provides additional functions or features for the printed wiring board assembly in addition to the functions available from the main printed wiring board. In some applications, the main printed wiring board and the mezzanine card are enclosed within a cover to protect the main printed wiring board, the mezzanine card, and electronic components coupled the mezzanine card and the main printed wiring board. 
       SUMMARY 
       [0005]    In one embodiment, the invention provides a printed wiring board assembly including a frame having a first pin-receiving aperture and a second pin-receiving aperture. A printed wiring board is mounted to the frame. A cover is coupled to the frame by at least one first fastener and has a third pin-receiving aperture and a fourth pin-receiving aperture. A first pin is positioned in the first pin-receiving aperture and the third pin-receiving aperture, and a second pin is positioned in the second pin-receiving aperture and the fourth pin-receiving aperture, to locate the cover with respect to the frame and to substantially prevent lateral movement of the of the cover with respect to the frame. A mezzanine board is mounted to the cover by at least one second fastener. The cover further includes a fifth pin-receiving aperture and a sixth pin-receiving aperture. The mezzanine board includes a seventh pin-receiving aperture and an eighth pin-receiving aperture. A third pin is positioned in the fifth pin-receiving aperture and the seventh pin-receiving aperture, and a fourth pin is positioned in the sixth pin-receiving aperture and the eighth pin-receiving aperture, to locate the mezzanine board with respect to the cover and to substantially prevent lateral movement of the mezzanine board with respect to the cover. 
         [0006]    In another embodiment the invention provides a method of assembling a printed wiring board assembly including a printed wiring board, a frame, a cover, and a mezzanine board. The method includes mounting the printed wiring board to the frame, locating the cover with respect to the frame by way of a first pin and a second pin, fastening the cover to the frame, locating the mezzanine board with respect to the cover by way of a third pin and a fourth pin, and fastening the mezzanine board to the cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a top perspective view of a printed wiring board assembly embodying the present invention. 
           [0008]      FIG. 2  is a cross-sectional view of the printed wiring board assembly of  FIG. 1  taken along line  2 - 2  of  FIG. 1 . 
           [0009]      FIG. 3  is an enlarged view of a portion of  FIG. 2  illustrating an exemplary connector that could be used with the printed wiring board assembly of  FIG. 1 , with a portion removed. 
           [0010]      FIG. 4  is a bottom side view of the printed wiring board assembly of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0012]      FIG. 1  illustrates a printed wiring board (PWB) assembly  10 . Referring to  FIG. 2 , the PWB assembly  10  includes a motherboard or main PWB  14 . In the illustrated construction, electronic components  18  are coupled to the main PWB  14  as is understood in the art. While the main PWB  14  has been described as a printed wiring board and the terms ‘printed wiring board’ and ‘PWB’ are used herein to describe other components of the assembly  10 , it should be understood that the terms ‘printed wiring board’ and PWB can include printed circuit boards, etched wiring boards, and the like. 
         [0013]    The PWB assembly  10  further includes a frame  20  and a cover  22  that is coupled to the frame  20  to create a cavity  26 . In the illustrated construction, the main PWB  14  is bonded to the frame  20  within the cavity  26  using a bonding material  30  such as epoxy, glue, other adhesives, and the like. In one construction, the frame  20  is a cooling frame that acts as a heat sink to transfer heat away from the main PWB  14 . As would be understood by one of skill in the art, the main PWB  14  can generate heat during operation. Thus, the frame  20  transfers heat away from the main PWB  14 . The frame  20  and the cover  22  are preferably made from a thermally conductive material such as aluminum, steel, or another metal that acts as a heat sink, but they could also be made from plastic, ceramic, or other materials. 
         [0014]    The cover  22  includes an upper wall  32  and sidewalls  34  that extend from the upper wall  32 . The upper wall  32  includes an outer surface  36  that is located outside of the cavity  26  and an inner surface  38  that is located within the cavity  26 . As best seen in  FIG. 2 , an aperture  40  extends through the upper wall  32  of the cover  22 . 
         [0015]    Referring to  FIGS. 2 and 4 , the cover  22  is coupled to the frame  20  using pins  42  and fasteners  44 . The pins  42  are permanent pins in the illustrated construction. In the illustrated construction, the fasteners  44  are screws, and in other constructions, other suitable fasteners and other types of threaded fasteners can be utilized. 
         [0016]    To assemble the cover  22  and the frame  20 , each of the permanent pins  42  (two pins are used in the illustrated construction) is inserted into an aperture  46  in the cover  22  and an aperture  48  in the frame  20 . The pins  42  are utilized to locate the cover  22  with respect the frame  20 . A tight tolerance is maintained between the pins  42  and the apertures  46  and  48  of the cover  22  and the frame  20  such that the pins  42  hold the cover  22  from moving laterally with respect to the frame  20  or the directions of arrows  50 . Then, the screws  44  are inserted into apertures in the frame  20  and the cover  22  to fasten the cover  22  to the frame  20 . The pins  42  tightly maintain the relative position of the cover  22  with respect to the frame  20  as the screws  44  are inserted into the cover  22  and the frame  20 . The pins  42  prevent substantial lateral movement of the cover  22  with respect to the frame  20  as the screws  44  are inserted, which can be caused by misalignments between the apertures for the screws  38  in the cover  22  and the frame  20 . 
         [0017]    Referring to  FIGS. 1 and 2 , the PWB assembly  10  further includes a peripheral component interconnect mezzanine card (PMC)  52 . In the illustrated construction, electronic components  54  are coupled to the PMC  52  as is understood in the art. Also, as would be understood by one of skill in the art, the PMC  52  is utilized with the main PWB  14  to provide additional functionality or features to the PWB assembly  10 , such as optional features customized for a particular application. The PMC  52  is electrically coupled to the main PWB  14  using PMC connectors  58  and  60 . Each of the PMC connectors  58  and  60  includes a first half  64  that is fixed to the PMC  52 , and a second half  68  that is coupled to the main PWB  14 . Referring to  FIG. 3 , in the illustrated construction, the PMC connector  64  coupled to the PMC  52  includes pins, plugs or other male-type components  72 , and the PMC connector  68  coupled to the main PWB  14  includes apertures, receptacles, or other female-type components  76  that receive the male-type components  72  to electrically couple the PMC  52  and the main PWB  14 . In one construction, the PMC connectors  58  and  60  are standard sixty-four pin connectors or plug/receptacle connectors, which are well known in the art. One type of plug/receptacle connector combination is the AMP Free Height Surface—Mount Connectors sold by Tyco Electronics. 
         [0018]    In the illustrated construction, the PMC  52  is coupled to the outer surface  36  of the cover  22  such that the PMC connectors  64  of the PMC  52  extend through the aperture  40  of the cover  22 . While the illustrated PMC  52  is coupled to the outer surface  36  of the cover  22 , in other constructions, the PMC  52  can be coupled to the inner surface  38  of the cover  22 . However, by coupling the PMC  52  to the outer surface  36  of the cover  22 , and adjacent the aperture  40 , electronic components  54  can be coupled to both sides of the PMC  52  as illustrated in  FIG. 2 . 
         [0019]    With continued reference to  FIGS. 1 and 2 , the PMC  52  is coupled to the cover  22  using pins  84  and fasteners  86 . In the illustrated construction, the fasteners  86  are screws. In other constructions, the fasteners  86  can be other suitable fasteners, including other types of threaded fasteners and the like. Also, in the illustrated construction, the pins  84  are tooling pins. As would be understood by one of skill in the art, tooling pins are pins having at least two pieces that can be manually separated such that the tooling pin can removably couple components. In other constructions, other types of pins, such as permanent pins and the like, can be utilized. 
         [0020]    Referring to  FIGS. 1-3 , to assemble the PMC  52  to the cover  22  and the main PWB  14 , the PMC connectors  64  of the PMC  52  are coupled to the PMC connectors  68  of the main PWB  14 , as is understood in the art. Next, the pins  84  (two pins in the illustrated construction) are inserted through apertures  88  of the PMC  52  and into apertures  92  in the cover  22 . The pins  84  are used to locate or position the PMC  52  with respect to the cover  22  and the main PWB  14 . A tight tolerance is maintained between the pins  84  and the aperture  88  and  92  such that the pins  84  hold the PMC  52  from moving laterally (in the direction of arrows  50 ) with respect to the cover  22  and the main PWB  14 . Also, because the pins  84  are tooling pins, the pins  84  also inhibit movement of the PMC  52  in the vertical direction, or in the direction of arrow  96 . Then, the screws  86  are threaded through apertures in the PMC  52  and the cover  22  to fasten the PMC  52  to the cover  22 . As the screws  86  are inserted into the cover  22 , the pins  84  tightly maintain the relative position of the PMC  52  with respect to the cover  22  while the pins  42  tightly maintain the relative position of the cover  22  with respect to the main PWB  14 . The pins  84  prevent substantial lateral movement of PMC  52  with respect to the cover  22  that can be caused by misalignments between the apertures for the screws  86 . Furthermore, because the pins  84  are tooling pins, the PMC  50  is removably coupled to the cover  22  and the PMC  54  can be easily removed from the PWB assembly  10  and a different PMC, possibly having other features, can be coupled to the PWB assembly  10  as discussed above. 
         [0021]    As would be understood by one of skill in the art, the PMC connectors  58  and  60 , particularly the pins or plugs  72 , can be delicate and are easily bent or broken. Therefore, it is desirable to hold the mating halves  64  and  68  of the PMC connectors  58  and  60  with respect to each other within a tight tolerance in order to protect the integrity of the mating halves  64  or plugs  72 . As discussed above, the pins  84  prevent lateral movement of PMC  52  with respect to the cover  22  as the screws  86  are inserted and the pins  42  prevent lateral movement of the cover  22  with respect to the main PWB  14 . Thus, the pins  84  and  42  prevent substantial relative movement between the mating halves  64  and  68  of the PMC connectors  58  and  60  during assembly. 
         [0022]    The PWB assembly  10  can be used in any suitable application, such as avionics, marine electronics, embedded computing, rack and panel servers, and the like. In such applications, the PWB assembly  10  can be exposed to shocks, vibrations, handling or transportation, and the like. The ruggedized connection between the cover  22  and the frame  20  reduces the amount of shock, vibration, and force exposed to the PMC connectors  58  and  60 . The pins  42  between the frame  20  and the cover  22  absorb shock, vibration, etc., transferred to the cover  22  and tightly hold the cover  22  from lateral movement with respect to the frame  20 . Therefore, shocks, vibrations, etc., transferred to the PMC connectors  58  and  60  are minimized. 
         [0023]    Thus, the invention provides, among other things, an improved printed wiring board assembly. Various features and advantages of the invention are set forth in the following claims.