This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/264,760 filed Jan. 29, 2001, the complete disclosure of which is hereby expressly incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electrical connector system for high-density interconnection of data cables and the like, and in particular, to an improved receptacle connector for such high-density electrical connectors, exhibiting enhanced electrical performance. 
     2. Summary of the Prior Art 
     It is common in building wiring closets where hubs and routers are located for distribution and/or storage of data, to have a plurality of racks and panels with multiple electrical interconnections formed by multiple cables. It is commonplace to have such electrical connections made by connection systems commonly known as modular plugs and jacks, the so-called RJ-45 connection system, or other systems such as the RJ-21. Separate connection systems have traditionally been used due to the speed of the data, the need to minimize EMI radiation, as well as the need to minimize cross talk between adjacent lines in the same connector. 
     One electrical connection system useful with data interconnections as described above is shown in U.S. Pat. No. 5,066,236 to Broeksteeg, incorporated herein by reference. Such an electrical connector system is modular in nature incorporating a plurality of side-by-side printed circuit board mountable connector housings having a plurality of contact arrays insert molded in a web of insulating material to include contact portions which extend into the housings and are positionable adjacent to a mating face, and a printed circuit board contact portion for mounting to a printed circuit board. The Broeksteeg design also shows in the overmolded webs, an air pocket existing over a portion of the terminals, for the purpose of exposing a portion of the terminals to air. This performs an isolation function thereby changing the impedance, and matching the impedance for the various lengths of terminals. While the Broeksteeg design is an excellent concept, he was not concerned with the centerline spacing which is required for a mating interface to hubs, routers and servers or the like. 
     The objects of the invention are to improve upon the shortcomings as mentioned above. 
     SUMMARY OF THE INVENTION 
     The objects of the invention have been accomplished by providing an electrical connector for use with twisted pair cable, where the connector comprises a housing portion having a plurality of electrical contacts positioned in rows and columns. The contacts are arranged in pairs, for mated reception with twisted pairs in a cable. The centerline spacing between contacts of pairs of contacts is less than the centerline spacing between side-by-side contacts of adjacent pairs. The plurality of electrical contacts is defined by a plurality of vertical columns of contacts, where each column is over-molded with a web of insulative material. The contacts are over-molded such that the overmolded portion is substantially rectangular. Preferably, the contacts are arranged in a substantially flat plane, with the plane being laterally asymmetric relative to the over-molded webs, thereby defining a thin web of material on one side of the plane and a thick web on the other side of said web. The over-molded webs are of substantially the same thickness. Contact pairs are arranged such that thin webs are positioned between contacts of the same pair, and thick webs are positioned between contacts of adjacent pairs. The thick webs include air pockets exposing a portion of the contact length, the air pockets being aligned in adjacent webs of adjacent pairs, to define a thick pocket between side-by-side contacts of adjacent pairs, whereby the impedance is balanced between contacts. The electrical contacts, over-molded in said web, have varying progressive lengths, and said air pockets vary in length in relation to the length of the contacts. 
     In another embodiment of the invention, an electrical connector for use with twisted pair cable comprises a housing portion having a plurality of electrical contacts positioned in rows and columns. The contacts are arranged in pairs for mated reception with twisted pairs in a cable. The pairs of contacts comprise side-by-side contacts in the same row, and the contacts in a pair have a thin web of insulation between them, and side-by-side contacts of adjacent pairs have a pocket of air between them. This increases the impedance, and minimizes the cross-talk between pairs. 
     In the preferred embodiment of this version, the centerline spacing between contacts of the same pair is less than the centerline spacing between side-by-side contacts of adjacent pairs. The plurality of electrical contacts is defined by a plurality of vertical columns of contacts, where each column is over-molded with a web of insulative material. The contacts are over-molded such that the overmolded portion is substantially rectangular. The contacts are arranged in a substantially flat plane, with the plane being laterally asymmetric relative to the over-molded webs, thereby defining a thin web of material on one side of said plane and a thick web on the other side of said web. The over-molded webs are of substantially the same thickness. The pairs are arranged such that thin webs are positioned between contacts of the same pair, and thick webs are positioned between contacts of adjacent pairs. The thick webs include air pockets exposing a portion of the contact length, the air pockets being aligned in adjacent webs of adjacent pairs, to define a thick pocket between side-by-side contacts of adjacent pairs, whereby the impedance is balanced between contacts. The contacts, over-molded in the web, have varying progressive lengths, and the air pockets vary in length in relation to the length of the contacts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view showing the plug connector and receptacle connector poised for interconnection; 
     FIG. 2 shows an exploded perspective view of the receptacle connector of FIG. 1; 
     FIG. 3 shows a top front perspective view of the receptacle housing for use with the receptacle of FIG. 1; 
     FIG. 4 shows a rear perspective view of the receptacle housing for use with the receptacle of FIG. 1; 
     FIG. 5 shows a rear plan view of the housing of FIG. 4; 
     FIG. 6 is a front plan view of the housing shown in FIG. 5; 
     FIG. 7 is a perspective view of the receptacle shielding shroud; 
     FIG. 8 is a front plan view of the shielding shroud of FIG. 7; 
     FIG. 9 shows a perspective view of the outer shielding for the preferred receptacle assembly; 
     FIG. 10 shows a perspective view of the receptacle board lock member; 
     FIG. 11 shows a side plan view of the stamped lead frame of one of the contact assemblies; 
     FIG. 12 shows a side plan view of the over-molded web of material over the stamped lead frame of FIG. 11; 
     FIG. 13 shows an end view of the over-molded lead frame of FIG. 12; 
     FIG. 14 shows a side plan view of another overmolded web of material over the stamped lead frame of FIG. 
     FIG. 15 shows an end view of the over-molded lead frame of FIG. 14; 
     FIGS. 16-21 show various over-molded lead frames for the embodiment of FIG. 1; and 
     FIG. 22 shows an underside perspective view of the receptacle assembled, less the outer shield; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With respect first to FIG. 1, an electrical interconnection is shown as comprised of a plug connector  2  and a receptacle connector  4 . The plug connector  2  is adapted to be connected to a shielded cable  6  which preferably contains a plurality of twisted pair conductors, whereas receptacle  4  is adapted to be connected to a printed circuit board (not shown). Both electrical connectors are fully shielded where the plug connector  2  includes a shielded enclosure  8  which is preferably a die-cast housing of two similar halves, whereas receptacle  4  includes a shield  10  which in the preferred embodiment is a stamped metallic housing. 
     Each electrical connector also includes a mating interface comprised of a shielding shroud, plug connector  2  having a shielding shroud shown generally at  12  which is profiled to receive in shielding engagement, the shielding shroud  14  of receptacle  4 . Finally, plug connector  2  includes elongate jackscrews  16  and  18  which are profiled for threaded engagement with complementary threaded posts  20  and  22 , respectively, of the receptacle  4 . 
     It should be appreciated that, when the jackscrews  16 ,  18  are fully threaded into their respective threaded posts  20 ,  22 , the two electrical connectors  2 ,  4  are in a fully mated condition where electrical terminals within plug connector  2  are fully electrically engaged with electrical terminals in receptacle  4 , as will be described in greater detail herein. The interface configuration is more described in co-pending patent application filed on even date as Ser. No. 60/264,761 (attorney&#39;s docket number 17628) incorporated herein by reference. The plug connector is described more fully in co-pending patent application filed on even date as Ser. No. 60/264,763 (attorney&#39;s docket number 17629), incorporated herein by reference. 
     With respect now to FIG. 2, the receptacle  4  is generally comprised of the outer shield member  10 , the front shielding shroud  14 , an inner housing  30 , boardlock members  32 , and a terminal lead frame assembly shown best at  40 . With respect now to FIGS. 3 and 4, the housing  30  will be described in greater detail. 
     Housing  30  generally includes side walls  44  and  46  with an intermediate top wall  48 . The side walls  44 ,  46  and top wall  48  together form a contact receiving area  50  intermediate side surfaces  52 ,  54 , and rearward of rear face  56 . As shown in FIG. 3, the housing  30  further includes a front face  58  having an integrally molded shroud portion  60  extending forwardly therefrom having a front face  62 . The shroud member  60  includes two rectangular recesses shown at  64  and  66  (FIGS. 3 and 6) which extend rearwardly to rear face  56  (FIG.  4 ). As shown in FIG. 6, the openings  64  and  66  form therein upper and lower surfaces, for example, upper surface  68  and surface  70  of opening  64 , and upper surface  72  and lower surface  74  of opening  66 . Also, side-by-side terminal receiving slots  80  extend through the rear wall  56  and partially into surfaces  68 ,  70 ,  72 , and  74  as best shown in FIGS. 3-6. 
     While the terminal receiving slots are shown generally at  80 , it should be appreciated from FIGS. 5 and 6 that a plurality of positions exist, extending in horizontal rows and vertical columns. As shown best in FIG. 5, in the preferred embodiment of the invention, there are four rows of terminal receiving slots  80 , and fourteen vertical columns. More specifically, the terminal receiving slots are, from left to right as viewed in FIG. 5, positions  82 A,  82 B;  84 A,  84 B;  86 A,  86 B;  88 A,  88 B;  90 A,  90 B;  92 A,  92 B; and  94 A,  94 B. 
     Housing  30  further includes latching projections  100  extending from top wall  48  (FIG. 3) as well as latching projection  102  extending from lower wall  104  (FIG.  4 ). Housing member  30  also includes apertures  110  and  112 , which open up into respective square cavities  114 ,  116  (FIG.  4 ), as further described herein. The housing  30  also includes recessed wall portions  120 ,  122  having elongate projections  124  and  126 . Recessed wall portion  120  further includes cut-out portions at  130  and a lower standoff wall  132  forming locking edges  134 . Likewise, recessed wall portion  122  includes cut-out portions  135 , a standoff wall at  136  having locking edges at  138 . 
     As shown best in FIGS. 7 and 8, shroud  14  generally includes a front wall portion  150  having apertures  152  and  154  extending therethrough. Latching ears  156  extend from top and lower edges of the wall  150  and include latching apertures  160 . A drawn shroud portion  170  extends integrally from the wall portion  150  and is complementary to the shielding shroud  12  of the plug connector which was described in FIG.  1 . Shroud portion  170  includes top and bottom wall portions  172  and  174  and side wall portions  176  and  178 . Side wall portion  176  is angled upwardly and outwardly so as to define an obtuse angle relative to lower wall  174  and an acute angle relative to top wall  172 . Side wall  178  includes a portion  180  extending generally vertical relative to lower wall  174  and a concave radiused portion  182  which extends between side wall portion  180  and upper wall portion  172 . It should be appreciated that the shroud portion  170  is profiled to interferingly fit within shroud portion  12 . 
     With reference now to FIG. 10, the boardlock member  32  generally includes a plate section  190  having an elongate opening at  192 , and folded-over lower tab portions  194 . Tabs  196  extend from opposite ends of the plate portion, while compliant boardlock portions  198  extend from a lower edge of the plate portion  190 . 
     With reference now to FIG. 9, the outer shield  10  will be described in greater detail. Outer shield member  10  includes a front face  200  having side walls  202 ,  204  extending integrally therefrom. Also, a top wall  206 , rear wall  208 , and lower wall  210  extend therefrom. Openings  212 ,  214  are provided to overlap with openings  152 ,  154  in shielding shroud  14  (FIG.  8 ). Furthermore, integral shielding contacts  220  extend from the marginal side edges of front face  200  and extend into side walls  202 ,  204 , top wall  206 , and lower wall  210 . Furthermore, printed circuit board tines  222  extend downwardly from side walls  202 ,  204 , and from rear wall  208 . An opening  224  through front face  200  is like profiled as the shroud portion  170 , so as to fit thereover. 
     With reference now to FIGS. 11-21, the terminal assembly  40  will be described which includes a plurality of overmolded terminal lead frames, shown in FIGS. 16-21. With reference first to FIG. 11, a lead frame is shown generally at  250  which is a stamped and formed lead frame including a plurality of contacts  252 ,  254 ,  256 , and  258 . In the embodiment of FIG. 11, the terminals  252 - 258  are still retained by the integral carrier strip at  260 . However, it should be understood that the carrier strip  260  will be removed for final assembly. With respect still to FIG. 11, the terminals generally include contact arms  252   a ,  254   a ,  256   a , and  258   a . Contact portions  252   b ,  254   b ,  256   b , and  258   b  extend integrally forwardly therefrom. Furthermore, leg portions  252   c - 258   c  extend from the arm portions  252   a - 258   a , respectively, and include printed circuit board tine portions  252   d - 258   d.    
     With reference now to FIGS. 16-21, a plurality of overmolded subassemblies are shown at  302 - 312 . It should be understood that all of the subassemblies  302 - 312  begin with the identical lead frame  250 , but that the lead frame  250  is overmolded in a different manner depending upon which terminal subassembly is required. More specifically, with reference to FIGS. 12-15, the inserts are defined by two different overmolded webs, that is, webs  320  and  322 . Overmolded web  320  includes a side surface  324  and an opposite side  326 . Meanwhile, overmolded web  322  includes a side surface  328  and an opposite side  330 . It should be understood by comparing FIGS. 12 and 14 with those of FIGS. 18 and 19, that subassembly  306  is depicted in FIG. 14, whereas subassembly  308  is depicted in FIG.  12 . 
     The terminal subassemblies are designed, such that the substantially solid side wall, for example,  324 ,  328 , always has the smallest distance to the centerline of the lead frame  250 . Furthermore, the lead frames  250  are positioned in the overmolded webs so as to be asymmetric, whereby distance D 1  in FIGS. 13 and 15 is smaller than distance D 2  in FIGS. 13 and 15. Furthermore, in the preferred embodiment of the invention, D 3  is equal to 1.2 mm, whereas distance D 1  equals 0.475 mm and distance D 2  equals 0.725 mm. Furthermore, and still with reference to FIGS. 16 through 21, each of the subassemblies  302 - 312  includes respective webs, for example,  302   a - 312   a ; first air pocket  302   b - 312   b ; second air pocket  302   c - 312   c ; third air pocket  302   d - 312   d ; and fourth air pocket  302   e - 312   e . It should also be appreciated that the air pockets are provided on the thick side of the respective webs  302   a - 312   a , that is, through the side where the thickness of the web is equal to D 2 . It should also be appreciated from reviewing FIGS. 16-21, that some of the contact portions have been severed, for example, by comparing FIG. 11 with FIGS. 16 and 17, that inserts  302  and  304  have front contact portions  256   b  and  258   b  removed, and that by comparing FIG. 11 with FIGS. 20 and 21, that inserts  310  and  312  have contact portions  252   b  and  254   b  removed. Finally, it should be understood that the terminal subassemblies are defined in pairs, such that subassemblies  302 ,  304 ;  306 ,  308 ; and  310 ,  312  are pairs of inserts as described herein. 
     With respect now to FIGS. 16-21, together with FIG. 5, it should be understood that terminal subassembly  302  is first inserted such that the contact portions  252   b  and  254   b  are positioned in terminal receiving slots  82   a . This positions the air pockets  302   b - 302   e  towards the left side as viewed in FIG. 5 or toward the outside. This also positions the thin web material, that is, distance D 1 , towards the right side or towards the center of the connector housing  30 . Terminal subassembly  304  is next inserted in terminal receiving slots  82   b  which positions the thin web of material of subassemblies  302  and  304  in abutting relation so that the centerline spacing between the lead frames in adjacent slots  82   a ,  82   b  is one millimeter. It should be appreciated that the next ten vertical columns, that is, columns  84   a ,  84   b ,  86   a ,  86   b ,  88   a ,  88   b ,  90   a ,  90   b , and  92   a ,  92   b  are next assembled in a similar manner where once again subassemblies  306  and  308  are positioned in side-by-side relation with the terminal portions  252   b - 258   b  in respective slot  84   a , etc. It should be appreciated that, as assembled, for example, air gap  306   b  is positioned adjacent to and adjoining air gap  304   b  in the adjacent contact assembly  304 . It should also be appreciated that terminal subassemblies  306  and  304 , while adjacent contact assemblies, are not in the same pair of terminals. Said differently, the terminals are paired such that a pair of terminals are adjacent and in the same row, for example, slots  82   a ,  82   b ;  84   a ,  84   b ; and the like. It should also be appreciated that five pairs of subassemblies  306  and  308  are positioned in their respective slots  84   a - 92   b  as these are like vertical columns of terminal receiving slots. Finally, subassemblies  310  and  312  are positioned in respective slots  94   a  and  94   b , once again with their thin webs of material being intermediate the lead frames  250 . 
     As positioned in the housing, the terminals of a pair, for example, terminals  252   b  of subassembly  302  and terminal  252   b  of subassembly  304  are positioned with the centerline spacing of one millimeter. Likewise, the adjacent terminals in different pairs of terminals, for example, terminal  252   b  of subassembly  304 , and terminal  252   b  of subassembly  306 , have a centerline spacing between them of 1.5 millimeters. Thus, as positioned in the housing, the one-millimeter spacing between pairs of terminals maximizes the coupling between the pairs, whereas the 1.5 mm spacing between adjacent contacts of different pairs, together with the air gap defined by their abutting air gaps maximizes the impedance between them to minimize cross-talk. 
     With the terminal subassemblies as described above, the remainder of the receptacle  4  will be described in greater detail. The shielding shroud  14  is connectable to the housing  30  by snapping the openings  160  (FIG. 7) over the latch projections  100  (FIG. 3) on the housing. The boardlock members  32  are then attached to the housing  30 , with the tabs  196  (FIG. 10) positioned in slots  130 , with tabs  194  positioned behind edges  138  and with elongate slot  192  positioned over elongate projection  124 . With the shielding shroud  14 , terminal subassemblies, and boardlock  32  assembled to the housing  30 , the assembly is completed by assembly of the shield  10  over the housing  150 . 
     A square threaded insert  300  is positioned in respective square openings  114 ,  116  and the shielding member  10  is thereafter positioned over the housing  30  such that shield extension  170  extends through opening  224  of the shield  10 . The threaded posts  20  and  22  can thereafter be positioned through openings  212 ,  214 , through openings  152 ,  154  (FIG.  8 ), and thereafter through openings  110 ,  112  to be threadably connected with the square inserts  300 . This retains the threaded posts  20 ,  22  to the front face of the receptacle for connection with the plug  2 . 
     To connect the two connectors together, it should be appreciated that the shroud portion  170  is inserted within the shielding shroud  12 . This positions of respective shroud portions  12 ,  14  in contact therewith. This also interconnects pairs of terminals in the receptacle  4 , for example, terminals  252   b  of subassembly  302 , and terminal  252   b  of subassembly  304 , with one of the twisted pairs of wire in cable  6 . This also provides for an excellent electrically compensated assembly. As mentioned above, the thin web of material between adjacent contacts of a pair, maximizes the coupling between the pair. Furthermore, the alignment of the air gaps between adjacent pairs minimizes the cross-talk between them.
A plug and receptacle assembly comprises a plug connector and receptacle connector, for high-density interconnections of data cable. The two connectors are fully shielded and include a mating profile including a modified D-shaped configuration. The receptacle assembly includes a plurality of overmolded webs of lead frames. The webs are overmolded laterally asymmetric to provide a thin web on one side, and a thick web on the other, where air pockets project through the thick webs and expose portions of contacts. The overmolded webs are stacked one against the other such that thin webs are positioned intermediate contacts in the same pair, whereas the thick webs, and air pockets are positioned one against the other in adjacent contacts of adjacent pairs.