Abstract:
A spacer and electrical connector assembly for printed circuit boards includes a first member to be placed between two of the printed circuit boards to provide a required spacing between the printed circuit boards. The assembly also includes at least one second member disposed adjacent to the first member, the second member extending along a length of the first member and at least partially bracketing an upper surface and a lower surface of the first member, thereby providing an electrical connection between the printed circuit boards. A plurality of contact portions that respectively receive the second member may be disposed on at least one of the upper and lower surfaces.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/730,704, filed on Nov. 28, 2012, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a mechanical spacer with built in, non-spring electrical contacts to be placed in a multiple printed circuit board (PCB) assembly to create an electrical connection between circuit paths of upper and lower circuit boards. Alternatively, one or both of the upper and lower circuit boards could be replaced with another circuit-based construction (e.g., LTCC, MID, etc.). 
         [0003]    A conventional PCB includes a plurality of electronic components, and is generally formed with a plurality of circuit paths for establishing electrical connection among the electronic components. The maximum number of circuit paths is proportional to the overall surface area of the printed circuit board. Printed circuit boards are often designed in multi-layered forms, thereby increasing the total surface area for forming circuit paths and for assembling the electronic components thereon. 
         [0004]    A plurality of spacer contact posts are conventionally sandwiched between the upper and lower circuit boards to create connection of the circuit paths of the circuit boards with each other and to facilitate heat-dissipation. 
       SUMMARY OF THE INVENTION 
       [0005]    In one embodiment, a spacer and electrical connector assembly for printed circuit boards is provided. The assembly includes a first member configured to be placed between two of the printed circuit boards to provide a required spacing between the printed circuit boards; at least one second member disposed adjacent to the first member, the second member extending along a length of the first member and at least partially bracketing an upper surface and a lower surface of the first member, thereby providing an electrical connection between the printed circuit boards. The assembly also includes a plurality of contact portions disposed on at least one of the upper and lower surfaces. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1A  is a cross-sectional view of a spacer assembly according to an embodiment of the invention. 
           [0007]      FIG. 1B  is an exploded view of  FIG. 1A . 
           [0008]      FIG. 2A  is a perspective view of the spacer assembly of  FIG. 1 . 
           [0009]      FIG. 2B  is a perspective view of an alternative spacer assembly 
           [0010]      FIG. 3  is a plan view of an alternative embodiment of a spacer assembly. 
           [0011]      FIG. 4  is a plan view of spacers distributed on a printed circuit board. 
       
    
    
       [0012]    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. 
       DETAILED DESCRIPTION 
       [0013]    The present invention includes a mechanical spacer  1  that holds two printed circuit boards  10 ,  20  (hereinafter “PCB” or “PCBs”) at a set distance from each other. The spacer  1  works in conjunction with an electrical connector  40  to provide an electrical connection between the two PCBs  10 ,  20  without the use of spring contacts (such as Pogo pins, leaf springs, or bare springs) in order to reduce cost and complexity, while providing a reliable mechanical and electrical connection. 
         [0014]    As shown in  FIG. 1A , the upper PCB  10  may be mechanically connected to the lower PCB  20  through a bushing and screw combination  30 . The bushing  31  may be formed of a metal such as brass or aluminum or may be a plastic component molded directly on a product housing  61  ( FIG. 3 ) so as not to be a separate component. In  FIG. 1A , a securing member or screw  32  is inserted through the lower PCB  20  and is secured within a concavity of the bushing  31 . The bushing  31  and screw  32  may optionally include male and female threads to form a secure connection, or may be otherwise joined together as known in the art. The compression load to establish the electrical connection between the PCBs  10 ,  20  is provided by the bushing and screw combination  30 , as shown by the arrows  33 . 
         [0015]    With continuing reference to  FIG. 1A , the spacer  1  may include a terminal  40  that has a bracket shape (C-shape) and extends along the vertical length of the spacer  1  and at least partially brackets the upper  2  and lower  3  surfaces of the spacer. However, other shapes for the terminal  40  could be used. The terminal  40  removes the need of expensive Pogo Pins and provides a more cost-effective solution to provide an electrical connection between the upper  10  and lower  20  PCBs. The terminal  40  may be in the form of a wire and may be raised above the upper surface  2  of the spacer  1  and raised below the lower surface  3  of the spacer  1  to ensure proper contact with the respective PCB  10 ,  20 . As best shown in  FIG. 1B , upper  41  or lower  42  surfaces of the terminal  40  may be respectively soldered to the upper PCB  10  or the lower PCB  20 . Alternatively, the terminal  40  may not be soldered to either PCB  10 ,  20  and thus be a loose and easily removable piece. The upper  41  or lower  42  surface of the terminal  40  may also include a “bump” protrusion  43 . The terminal  40  may be over-molded or stitched/inserted onto the spacer  40  using conventional methods. 
         [0016]    The assembly formed by the spacer  1  and terminal  40  can be a separate piece from either of the PCBs  10 ,  20 , and thus be a “pick and place” component that can be reflowed on one of the PCBs to reduce final manufacturing/assembly line steps. Additionally, when the spacer assembly is a separate piece, an electrically conductive adhesive or glue may be used in addition to the bushing and screw combination  30  to increase the reliability of the electrical and mechanical connections. Alternatively or additionally, a non-conductive adhesive can be used to secure the PCBs  10 ,  20  together to provide increased mechanical stability/resistance. 
         [0017]      FIG. 2A  shows a perspective view of a spacer  1  according to an embodiment of the invention. The spacer  1  may be formed of a plastic material and may have a generally L-shape with a plurality of locating pins or contacts  4  along an upper surface  2  thereof. The contacts  4  extend from the upper surface  2  to the lower surface  3 . A terminal  4  may respectively be secured in one or more of the contacts  4 . The contacts  4  may be flush with the surfaces  2 ,  3  or may be raised therefrom. A 5-contact spacer  1  is shown in  FIG. 2 , with the contacts  4  allowing the spacer to equally distribute a compression load among the five contacts  4  distributed along the upper surface  2  of the spacer  1 . However, additional or fewer contacts  4  are possible. The spacer can also have alignment posts  5  on the upper surface  2  and the lower surface  3  that fit into a corresponding hole in the PCB  10 ,  20  to align the upper  2  and lower  3  surfaces with the respective PCB  10 ,  20 . The spacer  1  may include alternate geometries or sizes to provide additional surface area  6  for contacts  4 . The inside surface of the spacer  1  can have a circular opening  7 , in order to fit around the bushing  31  in between the upper  10  and lower  20  PCBs. The circular opening  7  in the spacer  1  can be used in conjunction with the pin  5  to provide alignment and prevent rotation of the spacer  1 . 
         [0018]    In an alternative embodiment as shown in  FIG. 2B , the spacer  100  may be fully circular so that it surrounds the bushing between the PCBs ( FIG. 3 ). The spacer  100  shown in  FIG. 2B  is otherwise similar to the spacer  1  of  FIG. 1 , and includes an upper surface  102 , a lower surface  103  opposite the upper surface, pins  104  and a fully-enclosed center  107 . 
         [0019]    In an alternative embodiment shown in  FIG. 3 , the terminal  40  may be replaced with a molded interconnect device (MID)  50 . As is known in the art, a MID  50  is an injection-molded thermoplastic part with integrated electronic circuit traces printed on the thermoplastic material. As discussed above with respect to the terminal  40 , the MID  50  has a bracket shape (C-shape) and extends along the vertical length of the spacer  100  and brackets the upper  102  and lower  103  surfaces of the spacer. The MID  50  may be partially spaced from the spacer  100  to ensure proper contact with the PCBs  10 ,  20 . The upper  102  or lower surface of the MID  50  may also be respectively soldered to the upper PCB  10  or the lower PCB  20 . Alternatively, the MID  50  may not be soldered to either PCB  10 ,  20 , and thus be a loose piece. As discussed above, a conductive or non-conductive adhesive may be used to strengthen the connection when the MID  50  is a separate piece. The upper or lower surface of the MID  50  may also include a “bump” protrusion. As shown in  FIG. 3 , the upper and/or lower surfaces of the MID may also include a pad, for example made of gold. 
         [0020]    With continued reference to  FIG. 3 , the bushing and screw combination  30  may be replaced with a self-tapping screw  60  that fits into a bushing  61 . The bushing  61  is shown molded together with the PCB housing  61 , but may also be separate from the housing. 
         [0021]      FIG. 4  shows a plan view of two spacers  1  resting on diagonally opposite ends of a PCB  20 , providing ten total contact pins. As shown, the spacers  1  are spaced apart such that a circuit component  70 , such as a sensor, can be placed on the PCB  20  so as to avoid interference from the compression load  33  undertaken by the spacers  1 . 
         [0022]    While embodiments of the invention disclosed herein describe mechanical spacers for multiple printed circuit boards, one skilled in art should recognize that alternative configurations may be employed without deviating from the scope of the invention.