Patent Publication Number: US-6338635-B1

Title: Electrical connector with improved grounding bus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector, and particularly to a high speed electrical connector having an improved grounding bus. 
     2. Brief Description of the Prior Art 
     High speed connectors often include a grounding bus closely associated with signal terminals to promote high quality signal transmission therethrough. U.S. Pat. No. 5,536,179 discloses a conventional high speed connector, which comprises a dielectric housing, a module inserted in the housing which consists of a row of metal plates which is insert molded with an insulative body therearound, and two rows of signal contacts mounted respectively on opposite exterior sides of the insulative body. The insulative body usually forms a plurality of equally distanced dielectric ribs for isolating the signal contacts from each other. Each row of signal contacts is isolated from the other row by the insulative body and the metal plates, and signal contacts in the same row are isolated from each other by the dielectric ribs. With such a design, crosstalk between the two rows of the signal contacts is reduced by the insulative body and the metal plates, while crosstalk between the adjacent signal contacts of the same row cannot be effectively minimized merely by the dielectric ribs. 
     Hence, an improved electrical connector is required to overcome the disadvantage of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     A first object of the present invention is to provide an electrical connector with an improved module which has a plurality of conductive projections located between adjacent signal terminals for minimizing crosstalk therebetween; 
     A second object of the present invention is to provide an electrical connector with an improved module which has a plurality of dielectric ribs the length of which can be adjusted to match the impedance of the connector with the characteristic impedance of a circuit board on which the connector is mounted. 
     To achieve the above-mentioned objects, an electrical connector of the present invention includes a dielectric housing, a plurality of terminals, and a module. 
     The module includes a plurality of grounding members insert molded with an insulative body. A plurality of ribs is provided on a mounting surface of the insulative body. Each grounding member has a flat plate, a finger outwardly and downwardly extending from the flat plate, and a plurality of equally distanced projections protruding from the flat plate into the insulative body. The projections extend beyond the mounting surface of the insulative body and are embedded within corresponding ribs. 
     In assembly, the module is inserted downwardly into the housing and then the terminals are inserted upwardly to a position on the mounting surface of the insulative body of the module such that each terminal is positioned between neighboring ribs. 
     Since the insulative body is insert molded with the grounding members, its thickness can be minimized to enable the grounding members to be as close as possible to the terminals. The projections of the grounding members extend beyond the mounting surface of the insulative body to a position between the terminals, thereby significantly minimizing crosstalk between the terminals. 
     In addition, the ribs of the insulative body can be shortened during manufacturing so that the impedance of the connector can be adjusted to match the characteristic impedance of the circuit board on which the connector is mounted. 
     Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially exploded view of an electrical connector in accordance with the present invention; 
     FIG. 2 is a rear perspective view of a grounding bus consisting of a plurality of grounding members shown in FIG. 1; 
     FIG. 3 is a perspective view of an alternative integral module; 
     FIG. 4 is a rear perspective view of the module of FIG. 1 with terminals mounted thereto; 
     FIG. 5 is a view similar to FIG. 4 but with ribs thereof shortened; 
     FIG. 6 is an assembled view of FIG. 1; 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  of FIG. 6; and 
     FIG. 8 is a cross-sectional view taken along line  8 — 8  of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, an electrical connector  1  of the present invention comprises a dielectric housing  10 , a plurality of L-shaped terminals  20  arranged in four rows, and four modules  40  received in the housing  10  corresponding to the four rows of terminals  20 . 
     The housing  10  has a pair of opposite sidewalls  11  and a pair of opposite end walls  12  extending upward from a base  13  thereof, thereby forming a cavity  111  therebetween. The base  13  defines a plurality of first passageways  134  and second passageways  135  (see FIGS. 7 and 8) arranged in rows in communication with the cavity  111 . The housing  10  further defines a plurality of vertical recesses (not shown) for guiding insertion of the modules  40  and maintaining the modules  40  in position. 
     Each module  40  comprises a plurality of grounding members  42  insert molded with a T-shaped insulative body  44 . FIG. 2 shows a grounding bus (not labeled) consisting of the grounding members  42 . The grounding members  42  are isolated from each other and each has a flat plate  421 , an L-shaped finger  423  protruding outwardly and downwardly from a front side of the flat plate  421 , and a plurality of projections  425  protruding outwardly from a rear side of the flat plate  421 . The insulative body  44  maintains the isolated grounding members  42  in alignment with each other such that the flat plates  421  thereof are contained in the same plane. The fingers  423  are for connecting with an external ground circuit of a circuit board (not shown) on which the connector  1  is mounted. The projections  425  of each grounding member  42  are spaced from each other at equal intervals. Each projection  425  extends from near a top edge of a corresponding flat plate  421  to a portion near the top end of a corresponding finger  423 . 
     Alternatively, as shown in FIG. 3, the grounding members  42  may be interconnected by bridges  427  into one integral grounding bus (not labeled). 
     FIG. 4 shows a rear side of the module  40  with the terminals  20  positioned thereon. The insulative body  44  forms a plurality of equally distanced ribs  441  projecting rearwards from a mounting surface  445  of the insulative body  44  for retaining the terminals  20  therebetween. The projections  425  of the grounding members  42  are embedded in corresponding ribs  441 . The thickness of the insulative body  44  and the size of the ribs  441  can be adjusted to match the impedance of the connector  1  with the characteristic impedance of the circuit board on which the connector  1  is mounted. FIG. 5 illustrates an alternative insulative body  44 ′ which has shortened ribs  441 ′ for positioning the terminals  20  therebetween. Adjusting lengths (that is, the vertical dimension) of the ribs  441 ′ adjusts the impedance of the connector  1  to match the characteristic impedance of the circuit board on which the connector  1  is mounted. 
     In assembly, also referring to FIGS. 6,  7  and  8 , the modules  40  are first downwardly inserted into the cavity  111  of the housing  10  whereby the fingers  423  extend into corresponding first passageways  134 . The terminals  20  are then inserted upwardly from a bottom side of the base  13  through the second passageways  135  to locations between adjacent ribs  441  of the insulative body  44 . The terminals  20  are positioned adjacent to the mounting surface  445 . Furthermore, the grounding members  42  on opposite ends of the module  40  extend beyond opposite lateral edges of the insulative body  44  for providing the terminals  20  with improved electrical performance. 
     Since the grounding members  42  are insert molded with the insulative body  44 , the thickness of the insulative body  44  located between the terminals  20  and the flat plates  421  can be minimized during manufacturing. Therefore, the grounding members  42  can be located as close as possible to the terminals  20  whereby the grounding effect is improved. Additionally, as is clearly shown in FIG. 8, the projections  425  of the grounding members  42  can protrude beyond the mounting surface  445  of the insulative body  44  and between the adjacent terminals  20 , thereby significantly reducing crosstalk between the terminals  20 . Alternatively, an engaging surface  429  of each projection  425  (see FIG. 2) may be substantially flush with the mounting surface  445  when the insulative body  44 ′ forms the shortened ribs  441 ′. The distance that the engaging surfaces  429  of the projection  425  protrude beyond the mounting surface  445  is also adjustable for efficiently minimizing crosstalk between the terminals  20 . 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the fill extent indicated by the broad general meaning of the terms in which the appended claims are expressed.