Abstract:
A circuit board assembly comprising a main board, a connector board, and connector pins. The main board has a first face and a second face and terminating in an edge having a mounting area, the mounting area comprising at least one mounting pad on at least one of the first and the second faces. The connector board having a first face and a second face and comprising at least one through hole between the first and second faces. At least one connector pin is disposed in the at least one through hole and having a portion extending beyond each of the first and second faces of the connector board, wherein the edge of the main board and the second face of the connector board are abutted and the portion of the connector pin extending beyond the second face of the connector board is attached to the at least one mounting pad.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to circuit board assemblies, and more particularly to a first circuit board and a second connector board that are connected together.  
       BACKGROUND OF THE INVENTION  
       [0002]     Electronically controlled tools, such as DC tools, are typically designed to be driven from a controller using a cable between the controller and the tool to permit the tool to be moved freely inside of a workspace. The cable is typically a two-way conduit for providing motor power, signals, and other control lines between circuit boards and/or electrical components located onboard both the controller and the tool. In designing such tools, however, it is often desirable to minimize the length of the tool to facilitate fitting the tool into confined spaces. To help achieve this, one way of connecting the tool to a cable without adding length is to dress the cable directly into the tool without using a connector. However, this approach makes replacement of the cable, a high wear item, difficult. An alternative approach is to integrate one side of a connector at one end of the tool for connection to a mating connector of a cable. However, by integrating the connector, this approach undesirably adds significant length to the tool.  
         [0003]     The foregoing illustrates limitations known to exist in present circuit board connector devices. Thus it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly an alternative circuit board connector assembly, which preferably includes both the circuit boards and connector pins described herein, are provided including the features more fully disclosed hereinafter.  
       SUMMARY OF THE INVENTION  
       [0004]     According to the present invention, a circuit board assembly is provided having a main board, a connector board, and connector pins. The main board has a first face and a second face and terminating in an edge having a mounting area, the mounting area comprising at least one mounting pad on at least one of the first and the second faces. The connector board having a first face and a second face and comprising at least one through hole between the first and second faces. At least one connector pin is disposed in the at least one through hole and having a portion extending beyond each of the first and second faces of the connector board, wherein the edge of the main board and the second face of the connector board are abutted and the portion of the connector pin extending beyond the second face of the connector board is attached to the at least one mounting pad.  
         [0005]     The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a perspective view of a conventional circuit board assembly according to the prior art;  
         [0007]      FIG. 2  is a perspective view of a circuit board assembly according to the present invention;  
         [0008]      FIG. 3  is a top view of the circuit board assembly shown in  FIG. 2 ;  
         [0009]      FIG. 4  is a side view of the circuit board assembly shown in  FIG. 2 ;  
         [0010]      FIG. 5  is a bottom view of the circuit board assembly shown in  FIG. 2 ;  
         [0011]      FIG. 6  is an enlarged view of the portion shown bounded by the dashed-dotted line in  FIG. 4 ;  
         [0012]      FIG. 7  is an end view of the circuit board assembly shown in  FIG. 2 ;  
         [0013]      FIG. 8  is a partial planar view of the unassembled edge of a main board for a circuit board assembly according to the present invention;  
         [0014]      FIG. 9  is a front view of an unassembled connector board for a circuit board assembly according to the present invention;  
         [0015]      FIG. 10  is a perspective view of a connecting cable in the process of being assembled to a connector board of a circuit board assembly according to the present invention;  
         [0016]      FIG. 11  is a bottom view of the connecting cable and connector board of  FIG. 10  being attached to a main board of a circuit board assembly according to the present invention; and  
         [0017]      FIG. 12  is a partial sectional view of a tool housing configured to incorporate a circuit board assembly according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Shown in  FIG. 1  is a conventional circuit board assembly  5  that is typically installed into a housing of an electronically controlled tool and has an integral molded connector  18 . Circuit board assembly  5  includes a main printed circuit board  10  that is orthogonally fitted into slots in a first connector board  12  and attached thereto via solder disposed between solder pads  17  located on each board. First connector board  12  is in turn connected to a second connector board  14  via board-to-board pins  16  which are electrically connected to connector pins  19 . Second connector board  14  is provided to facilitate rerouting of trace connections between the connector pins  19 . Connector pins  19  are partially embedded in molded connector  18  and extend outward for connection to a female receptacle of a connecting cable (not shown). Molded connector  18  is typically made of a thermoplastic resin that is molded around connector pins  19 , board-to-board pins  16 , and the connector sockets (not shown) that join them. Generally, electrical connections are established between connector pins  19  and electrical components that are located either on main board  10  via associated printed circuitry (not shown) or elsewhere in the tool housing via connecting cable  24 .  
         [0019]     Although generally acceptable, the conventional circuit board assembly  5  described above suffers from numerous drawbacks including the addition of significant length to the tool. Moreover, a plurality of parts and manufacturing steps are required to make the conventional connector assembly thus making it both labor intensive and more costly to manufacture. According to the present invention, a circuit board assembly is provided that is easily assembled to achieve an integrated connector that reduces both the number of component parts and the associated space required to house them.  
         [0020]     The invention is best understood by reference to the accompanying drawings in which like reference numbers refer to like parts. It is emphasized that, according to common practice, the various dimensions of the connectors and the associated component parts as shown in the drawings are not to scale and have been enlarged for clarity. Referring now to the drawings, shown in  FIGS. 2-9 , a circuit board assembly  20  according to the present invention is shown comprising a main board  50  and connector board  30  that are joined together, preferably, in an orthogonal orientation as shown in  FIG. 4 .  
         [0021]     Main board  50  is a printed circuit board having a first face and a second face that include electronic and/or electrical components  56 , such as integrated circuits, and associated circuitry. Connector board  30  has at least one and, preferably, a plurality of through holes  31  (shown in  FIG. 9 ) in which are contained a corresponding at least one and, preferably, a plurality of connector pins  32 . As shown in the enlarged view of  FIG. 6 , preferably disposed circumferentially and located along the length of each of the connector pins  32  are flanges  34  for seating against the connector board  30  to prevent further forward axial motion once inserted into the plurality of holes  31 . Preferably, connector pins  32  are hollow on one end to permit the insertion of conducting wires to be attached as described in detail below.  
         [0022]     As shown in  FIG. 9 , each of the plurality of holes  31  of connector board  30  is plated with metal around its periphery to form bonding rings  35 . As discussed in detail below, connector pins  32  are soldered to bonding rings  35  achieving both the electrical interconnection of each pin to the bonding ring while mechanically preventing the pins from axially moving backward out of their respective holes. A printed circuit  33  (only part of the printed circuit being shown in  FIG. 9 ) may be provided, as is known in the art, with traces on either or both sides of connector board  30  to provide various interconnections between the pins. Alternately to or in conjunction with the printed circuit, wire interconnects (not shown) may be used to connect the connector pins  32 . Preferably, connector board  30  contains receiving slots  36  for receiving tab portions  55  located on both sides of a receiving notch  54  in the end of main board  50  that is to be joined. As seen best in  FIGS. 3, 6 , and  8 , receiving notch  54  is configured to receive the thickness of connector board  30  so that the tab portions  55  are flush with the surface of the connector board  30  from which the connector pins  32  outwardly extend.  
         [0023]     As shown in  FIG. 8 , at the rear edge of main board  50  on at least one and preferably both sides thereof, is at least one mounting pad that preferably is a plurality of electrical contact pads  52  which comprise part of the printed circuit  53  (only part of the printed circuit being shown). The printed circuit may be contained on both sides of the main board  50  with the two halves of the circuit being interconnected by plated through-holes (not shown), as is known in the art. Electronic and/or electrical components are mounted on the card, as is known in the art, with only a few exemplary components  56  being shown in the drawing.  
         [0024]     As discussed in greater detail below, attachment of the main board  50  to the connector board  30  is achieved by soldering at least one connector pin  32  to a corresponding contact pad  52  after the tab portions  55  of main board  50  are inserted into the receiving slots  36  of connector board  30 . As shown by the connecting arrows between  FIGS. 8 and 9 , this is accomplished by locating at least one hole  31  positioned on either or both sides of the main board  50  so that each is aligned with a corresponding contact pad  52 . To achieve a secure bond between the main board and the connector board, it is preferred that a plurality of electrical contact pads  52  are provided on each side of main board  50  with a plurality of corresponding holes  31  being aligned in two rows between which receiving slots  36  are located. Connector board  30  is preferably a printed circuit board on which printed circuit traces and the electrical contact pads can be provided to achieve desired interconnection configurations between the connector pins  32  and connector pads  52  of main board  50 . In this fashion, the connector pins that are used to mechanically secure the main board to the connector board may also serve the dual purpose of providing electrical connections between the boards.  
         [0025]     To help prevent angular motion of the connector pins  32  while connecting and disconnecting a cable, it is preferred that the connector board  30  is provided in a thickness that is sufficient to support the connector pins. Generally, thicknesses of about one-eighth of an inch adequately accomplish this purpose. As shown in  FIG. 7 , receiving slots  36  are advantageously shaped to allow tab portions  55  to be easily inserted with, preferably, an interference fit being provided there between. Alternatively, receiving slots  36  can be configured for a looser (e.g., larger) fit than a size-on-size fit.  
         [0026]     A typical assembly of a circuit board assembly according to the present invention will now be described. Turning to  FIGS. 10-11 , if connecting cables are to be included, the individual wires on one end are first stripped and then attached to conventional connector pins  19  by crimping the pins onto the individual wires. These conventional pins can include those such as such as connector pins available from Molex Inc. Lisle, Ill., to which a conventional pin connector is attached as shown in  FIG. 11 . As shown in  FIG. 10  outer cable shield  25  of connecting cable  24  is then pulled away from the other end of the cable and the individual wires are similarly stripped and then inserted through the proper holes in connector board  30  for connection to the hollow ends of connector pins  32 . Preferably, heat-shrinkable tubing  37  and  38 , such as that available as NP203 polyolefin tubing from Nelco Products, Inc., Pembroke, Mass., is included both over the cable and the individual wires, respectively, as shown. Connector pins  32  are then crimped in similar fashion to connector pins  19  over the individual wire strands with the difference being that they include a circumferential flange as described above. Preferably, a crimping tool such as a Model M22520/2-01 crimp tool available from Daniels Manufacturing Corporation, Orlando, Fla. is used to crimp connector pins  32 . Connector pins  32  are then pulled through connector board  30  until connector pin flanges  34  seat against a first face of the connector board. The connector pins  32  are then soldered in position to bonding rings  32  on a second face of the connector board  30  after which the shrink tubing  38  is slid over the pins and then shrunk. The outer cable shield  25  is then slid back toward connector board  30  and the heat shrink tubing  37  is then slid and shrunk over both ends of the cable shield. Tab portions  55  of main board  50  are then inserted into receiving slots  36  of connector board  30  so that the end of main board  50  is preferably flush with connector board  30  as shown.  
         [0027]     Assembly of circuit board assembly  20  is then continued by inserting into the plurality of holes  31  additional connector pins  32  required to make the connections needed with a connector of a controller cable. As described above, the connector pins  32  are pulled through connector board  30  until connector pin flanges  34  seat against a first face of the connector board and then soldered in position to bonding rings  35  on a second face of the connector board  30 . In the case of connector pins  32  that are aligned with and adjacent to contact pads  52 , these pins are soldered directly to the contact pads to provide the mechanical connection between the connector board  30  and the main board  50 . An electrical connection is also established by the solder  57  between the connector pins  32  and the contact pads  52  that may be used to connect the pins with other electrical components if electrical connections, such as those shown as printed circuit  53  in  FIG. 8  and/or other wire interconnects, are made with contact pads  52 . As described above, a printed circuit (such as that shown as printed circuit  33  in  FIG. 9 ) and/or wire interconnects (not shown) may be used to connect the connector pins  32  thereby achieving various desired interconnections therebetween.  
         [0028]     The completed circuit board assembly shown in  FIGS. 2-7  produced thereby may then be inserted into a tool housing  60  such as that shown in  FIG. 12 , which preferably includes a shoulder  62  that captures the connector board  30  upon sliding it therein. Also preferred is the use of an O-ring groove  63  into which an O-ring is placed to help secure and seal the circuit board assembly  20  in tool housing  60 .  
         [0029]     Although described above with respect to use with electric tools, it is contemplated that the circuit board assembly according to the present invention may be incorporated into other electrical devices having pin connectors in which a robust mechanical assembly and compact design are desired. While embodiments and applications of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein described. For example, although shown with exemplary electrical components and circuitry it is to be understood that various other electrical components with different trace circuit configurations may be utilized. It is understood, therefore, that the invention is capable of modification and therefore is not to be limited to the precise details set forth. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims without departing from the spirit.