Abstract:
A board mounted connector for a board to board connector system is disclosed which can be smaller, provide a more robust connection to a conductive circuit on a printed circuit board while allowing for a high degree of circuit design freedom on the board circuit due to the terminal insertion from the mating side of the housing where the terminals are generally above a bottom portion ( 33 ) of the non-conductive housing ( 31 ) adjacent the board. The housing ( 31 ) is provided with fitting holes ( 37 ) extending from an end surface ( 32   d ) on the side which mates with the male housing ( 21 ). The female terminals ( 35 ) have anchor portions ( 36 ) to be fitted into the fitting holes ( 37 ) of the female housing ( 31 ) and contact portions ( 35   b ) to engage terminals in a mating connector Forward end portions ( 36   a ) of the anchor portions ( 36 ) are soldered to a circuit terminal of the board ( 3 ). Cut out portions ( 39 ) in the rectangular frame portion ( 32 ) allow for the solder joint between the end portion ( 36   a ) and the conductive circuit ( 38 ) to be inspected.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a board mounted connector for connecting printed circuit boards to each other. 
         [0002]    Existing board to board connecting systems include a male, or plug connector, to be soldered to one board and a female, or receptacle connector, to be soldered to another board. The male and female connectors are designed to engage and mate with one another. The plug connector and the receptacle connector are respectively provided with plug terminals and receptacle terminals that are to be soldered to conductive circuits on the boards. When the mating plug and receptacle are mated together, the plug and receptacle terminals are in electrical engagement with each other thereby electrically connecting the conductive circuits from one circuit board to the other circuit board. 
         [0003]    Various types of board to board connectors have been used in the past. One such board connector has receptacle terminals with contact portions which electrically engage plug terminals in a mating plug connector, anchor portions for holding the receptacle terminals to a receptacle housing, and solder tail portions for soldering the receptacle terminals to a conductive circuit on a board. 
         [0004]    In this board to board connector, the contact portions and the solder tail portions are spaced apart from one another since the solder tail portions extend from the anchor portions beyond the sides of the connector housing. The use of this connector requires a larger footprint on the printed circuit board. Also, because the solder tail portion extends from a flexible elongated arm located on the exterior of the connector, the strength of the solder joint is diminished. Furthermore, because of the long length of the solder tail arm, the signal has to travel a longer distance before it electrically communicates with the circuit on the circuit board. This extra length can be a factor in timing with high speed signals. Finally, such a connector has only one point of electrical and mechanical engagement with the printed circuit board which can result in a weak mechanical and electrical connection. 
         [0005]    All of these characteristics are important for a connector with terminals which are inserted into a mating side of the connector housing opposite the side adjacent the printed circuit board. It is important that a bottom portion of the housing remains to prevent any short circuit between the terminals and the conductive circuits traveling under the housing after the terminals are inserted into the mating side of the connector. Providing this bottom housing portion will allow for more freedom of circuit designs on the printed circuit board. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the present invention, a connector that is mounted to a first printed circuit board is designed to mate with a connector mounted to a second printed circuit board so that conductive traces on both boards can be electrically connected to each other. The connector includes a non-conductive housing having a rectangular frame portion with a fitting hole in portions of the frame portion extending from the mating surface of the housing opposite the board mounting surface and a bottom portion located adjacent to the printed circuit board. A plurality of terminals are held in the housing. Each of the terminals have a support portion, a contact portion to be brought into electrical contact with the male terminal, a bridging portion provided between the support portion and the contact portion, and an anchor portion extending from the support portion and fitted into the housing fitting hole. A bottom portion of the housing is located between the printed circuit board and the bridging portion of the terminal. A forward end portion of the anchor portion protrudes from the housing through the fitting hole for a distance so that the end can be soldered to a circuit on the circuit board. 
         [0007]    According to another aspect of the invention, cut out portions are formed in the bottom of the frame portions along the sides of the connector housing near the board so that the solder joint formed between the end of the anchor and the board can be observed from the side of the board. 
         [0008]    According to still another aspect of the invention and as displayed in another embodiment of the present invention, a solder tail may extend from the support portion toward the printed circuit board so that the solder tail and the end of the anchor can both be soldered to a circuit on the printed circuit board. 
         [0009]    Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
           [0011]      FIG. 1  is a perspective view of the plug connector and the receptacle connector of a board connecting connector according to an embodiment of the present invention as separated from each other; 
           [0012]      FIG. 2  is a partial sectional view of the plug and receptacle connector of  FIG. 1  engaged with each other; and, 
           [0013]      FIG. 3  is a partial sectional view of a receptacle and plug connector mated together and illustrates another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    In the following, a board connecting connector according to an embodiment of the present invention will be described with reference to the drawings. As shown in  FIG. 1 , a board to board connector system  1  is arranged between opposing boards  2 ,  3 . ( FIG. 2 ). The connector system  1  includes a plug connector  11 , which is a male connector soldered to one board  2 , and a receptacle connector  12 , which is a female connector soldered to the other board  3 . When the plug and receptacle connectors are joined the respective terminals are electrically connected to each other. 
         [0015]    The plug connector  11  has a plug housing  21  made from a non-conductive material. The plug housing  21  has a bridging portion  22  formed as a rectangular flat plate, and relatively thick-walled fit-engagement protrusions  23  provided on either side of the bridging portion  22  and extending along the entire length of the bridging portion  22 . 
         [0016]    On the inner surface of the fit-engagement protrusion  23 , on either side, there are arranged a plurality of plug terminals  24 , which are male terminals to be soldered to the upper circuit board  2 . The plug terminals  24  are arranged at equal intervals. The plug terminals  24  have support portions  24   a , arranged and extending under the bottom surfaces  23   a  of the fit-engagement protrusions  23 , and U-shaped contact portions  24   b , extending downwards from one end of the support portions  24   a . The plug terminals  24  are formed integrally by stamping them from conductive metal. The bridging portion  22  of the housing  21  includes openings  22   a  to allow for the insertion of the plug terminals  24  from above the bridging portion  22  into the space between the fit-engagement protrusions  23 . 
         [0017]    The receptacle connector  12  has a receptacle housing  31 , which is a female housing made from a non-conductive material. The receptacle housing  31  has an outer rectangular or other shaped frame portion  32  into which the plug housing  21  of the plug connector  11  fits. A bottom portion  33  is provided on the bottom surface of the housing frame portion  32 . A central protrusion  34  is provided along the center of the bottom portion  33  and protrudes into the interior of the outer frame portion  32 . A fit-engagement recess  32   a  is formed on the inner side of the outer frame portion  32  and it surrounds the central protrusion  34  as shown in  FIG. 1 . 
         [0018]    On the inner side of the outer frame portion  32  of the receptacle housing  31 , there are arranged a plurality of receptacle terminals  35 , which are also called female terminals. The receptacle terminals  35  are inserted into the receptacle housing  31  from the side of the frame portion  32  which mates with the plug connector (shown as the top in the figures). The receptacle terminals  35  extend from the mating side end surface  32   d  (the top surface in FIG.  1 ) of the receptacle housing  31  to side surfaces  34   a  of the central protrusion  34  by way of the inner side surface  32   b  of the frame portion  32  and the inner bottom surface  33   a  of the bottom portion  33 . 
         [0019]    As shown best in  FIG. 2 , the receptacle terminals  35  have support portions  35   a  arranged in horizontal grooves  32   c  provided along the top mating side end surface  32   d  of the frame portion  32 . L-shaped bridging portions  35   d  extend downward from one end of the support portions  35   a . Contact portions  35   b  extend upwards from the bridging portions  35   d . The contact portions  35   b  each have resiliency and have at its free end an enlarged contact end, shown as chevron-shaped abutment portions  35   c  which are brought into contact with the contact portions  24   b  of the plug terminals  24 . The receptacle terminals  35  are formed integrally through stamping of a conductive metal plate. The terminals have a general U-shape between this contact and support portions. 
         [0020]    The bridging portions  35   d  of the receptacle terminals  35  are arranged along the bottom inner surface  33   a  of the bottom portion  33  of the receptacle housing  31 . The bottom portion  33  of the receptacle housing  31  extends between the bridging portions  35   d  and the board  3 . 
         [0021]    In the middle of the support portions  35   a  of the receptacle terminals  35 , there are provided linear anchor portions  36  extending substantially parallel to the contact portions  35   b  (or vertically as shown). On either side of the middle portions of the anchor portions  36  are recesses  36   b ,  36   b . The receptacle housing  31  has fitting holes or openings  37  formed therein which extend through the housing to the opposite surface of the mating side end surface  32   d . In the middle portions of the fitting holes  37 , there are provided protrusions  37   a ,  37   a  that engage with the recesses  36   b ,  36   b  of the anchor portions  36 . When the anchor portions  36  of the receptacle terminals  35  are press fit into the fitting holes  37 , the recesses  36   b ,  36   b  of the anchor portions  36  lock with the protrusions  37   a ,  37   a  of the fitting holes  37 . As a result, the receptacle terminals  35  are reliably fixed to the receptacle housing  31 . 
         [0022]    Solder portions  36   a  of the anchor portions  36  protrude outwardly beyond the surface  31   a  of the receptacle housing  31 . The solder portions  36   a  of the anchor portions  36  protrude far enough beyond the surface  31   a  to enable them to be soldered to a circuit  38  on the board  3  when the connector  12  is placed on the board. Since this anchor portion is short in height it is rigid and will not bend during engagement and disengagement of the two connectors, thus forming a very good mechanical engagement with the board  3 . 
         [0023]    Next, the operation of the board connecting system  1  will be described with reference to  FIG. 2 . When electrically connecting the boards  2 ,  3  by the board connecting system  1 , the support portions  24   a  of the plug terminals  24  of the plug connector  11  are soldered to the conductive circuit on one board  2 . As a result, the plug connector  11  is fixed to the board  2 . Further, the forward end portions  36   a  of the anchor portions  36  of the receptacle terminals  35  of the receptacle connector  12  are soldered to the conductive circuit  38  on the other board  3 . As a result, the receptacle connector  12  is fixed to the board  3 . 
         [0024]    When an attempt is made to insert the plug connector  11  into the receptacle connector  12 , the fit-engagement protrusions  23 ,  23  of the plug housing  21  are fitted into the fit-engagement recess  32   a  of the receptacle housing  31 , and the connectors  11 ,  12  are then mated with each other. When the plug connector  11  and the receptacle connector  12  have been mated with each other, the abutment portions  35   c  of the contact portions  35   b  of the receptacle terminals  35  abut the contact portions  24   b  of the plug terminals  24 . As a result, the plug terminals  24  and the receptacle terminals  35  are electrically connected to each other, and the boards  2 ,  3  are electrically connected to each other. 
         [0025]    The bottom portion  33  of the receptacle housing  31  extends between the bridging portions  35   d  of the receptacle terminals  35  and the board  3 . As a result, except for the solder portions  36   a  of the anchor portions  36 , a substantial portion of the receptacle terminals  35  are not exposed along the surface  31   a  of the receptacle housing  31  adjacent to the board  3 . Thus, the bridging portions  35   d  of the receptacle terminals  35  do not contact the circuit board  3 , so that it is possible to provide a conductive circuit on the surface of the board  3  opposed to the bridging portions  35   d . As a result, an improvement is achieved in terms of the degree of freedom for the circuit design on the board  3 . 
         [0026]    The end portions  36   a  of the linear anchor portions  36  of the receptacle terminals  35  protrude outwardly from the surface  31   a  of the receptacle housing  31  adjacent to the board  3 , and are soldered to the circuit terminal  38  of the board  3 . As a result, the receptacle connector  12  is fixed to the board  3 . Thus, there is no need to provide the receptacle terminals  35  with solder tail portions extending as elongated arms beyond the outer frame portion of the connector housing, so that it is possible to achieve a reduction in the size of the receptacle terminals  35  and of the entire receptacle connector  12 . Also the electrical length of the terminal is shortened which is important in high speed data transmission. To allow for the inspection of the solder joint under the housing  31  a cut out  39  is provided along the sides of the frame portions  32  near the board  3 . 
         [0027]    While in the above-described embodiment the receptacle terminals  35  are not provided with solder tail portions, it is also possible, as shown in  FIG. 3 , to form receptacle terminals with solder tail portions  41 . In the following description, the portions that are the same as those of  FIG. 1  are indicated by the same reference symbols, and a detailed description thereof will be omitted. Like the anchor portions  36 , solder tail portions  41  are provided which extend from the end portions of the support portions  35   a  toward the board  3 . 
         [0028]    The solder tail portions  41  are formed in a substantially reverse-L-shaped configuration. Short side portions  42  at the forward ends of the solder tail portions  41  are soldered to the board  3 . Further, the forward solder portions  36   a  of the anchor portions  36  are also soldered to the circuit terminal  38  of the board  3 . Since both the solder tail portions  41  and the anchor portions  36  are soldered to the conductive circuit on the board  3 , an improvement in the soldering strength is achieved. 
         [0029]    While in the above-described embodiment the receptacle terminals  35  are mounted by press fitting them into the receptacle housing  31 , it is also possible to mount the receptacle terminals  35  to the receptacle housing  31  by over-molding. In the case of manufacturing through over-molding, no recesses  36   b  are formed in the anchor portions  36 , and no protrusions  37   a  are formed in the fitting holes  37 . The portions of the receptacle housing  31  corresponding to the anchor portions  36  and the fitting holes  37  are formed such that their longitudinal sections are substantially in a straight line. 
         [0030]    It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.