Patent Publication Number: US-10763624-B1

Title: Receptacle connector having ground bus insert

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to receptacle connectors. 
     Receptacle connectors are used with an electrical connector system for electrically connecting a circuit board with another component, such as a plug connector. The receptacle connector includes signal contacts that provide electrical paths between the plug connector and the circuit board. At hired data rates, signal integrity of the receptacle connector is problematic. Ground contacts are typically provided between signal contacts to provide electrical shielding through the receptacle connector. However, routing of signal contacts and ground contacts through the connector may be difficult and increase the overall size of the receptacle connector. In the data communication industry, there is a desire for decreasing footprints of receptacle connectors on the circuit boards. However, smaller footprints lead to signal integrity problems within the electrical connector system. 
     A need remains for a cost effective and reliable receptacle connector for an electrical connector system. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a receptacle connector is provided including a contact module assembly and a front housing having a cavity receiving the contact module assembly. The contact module assembly includes a first contact module, a second contact module, and a ground bus insert. The first contact module includes a first dielectric frame holding a first contact leadframe including first signal contacts and first ground contacts. The second contact module includes a second dielectric frame holding a second contact leadframe including second signal contacts and second ground contacts. The first and second contact modules are stacked side by side with the ground bus insert between the first and second contact modules. The ground bus insert includes ground conductors electrically connected together. The ground conductors include first side rails and second side rails. The first side rails are electrically connected to corresponding first ground contacts. The second side rails are electrically connected to corresponding second ground contacts. The front housing has a receptacle slot at a front of the front housing configured to receive a plug connector. The first and second signal contacts and the first and second ground contacts are received in the receptacle slot to mate with the plug connector. 
     In another embodiment, a receptacle connector is provided including a contact module assembly including a first contact module, a second contact module, and a ground bus insert between the first contact module and the second contact module. The first contact module has a first dielectric frame holding a first contact leadframe having first signal contacts and first ground contacts. The first signal contacts have mating ends and mounting ends and the first ground contacts having mating ends and mounting ends. The mating ends of the first signal contacts are configured for mating with mating contacts of a plug connector. The mounting ends of the first signal contacts are configured for mounting to a circuit board. The second contact module has a second dielectric frame holding a second contact leadframe having second signal contacts and second ground contacts. The second signal contacts have mating ends and mounting ends and the second ground contacts have mating ends and mounting ends. The mating ends of the second signal contacts are configured for mating with mating contacts of the plug connector. The mounting ends of the second signal contacts are configured for mounting to the circuit board. The first and second contact modules are stacked side by side with the mating ends of the first and second signal contacts extending forward from the first and second dielectric frames in a first row and a second row on opposite sides of a gap configured to receive the plug connector. The ground bus insert includes ground conductors electrically connected together. The ground conductors include first side rails and second side rails. The first side rails are electrically connected to corresponding first ground contacts. The second side rails are electrically connected to corresponding second ground contacts. The receptacle connector includes a front housing having a cavity receiving the contact module assembly. The front housing has a receptacle slot at a front of the front housing configured to receive the plug connector. The mating ends of the first and second signal contacts are received in the receptacle slot to mate with the plug connector. The receptacle connector includes an outer housing having a chamber receiving the front housing. The outer housing is conductive and provides electrical shielding around the chamber. 
     In a further embodiment, an electrical connector system includes a plug connector and a receptacle connector mated with the plug connector. The plug connector has a circuit card having an edge extending between a first surface and a second surface. The circuit card has first plug contacts on the first surface and second plug contacts on the second surface. The receptacle connector includes a contact module assembly including a first contact module, a second contact module, and a ground bus insert. The first contact module includes a first dielectric frame holding a first contact leadframe including first signal contacts and first ground contacts. The second contact module includes a second dielectric frame holding a second contact leadframe including second signal contacts and second ground contacts. The first and second contact modules are stacked side by side with the ground bus insert between the first and second contact modules. The ground bus insert includes ground conductors electrically connected together. The ground conductors include first side rails and second side rails. The first side rails are electrically connected to corresponding first ground contacts and the second side rails are electrically connected to corresponding second ground contacts. The receptacle connector includes a front housing having a cavity receiving the contact module assembly. The front housing has a receptacle slot at a front of the front housing receiving the circuit card of the plug connector. The first and second signal contacts and the first and second ground contacts have mating ends received in the receptacle slot. The mating ends of the first signal contacts and the first ground contacts are arranged on a first side of the receptacle slot to mate with the first plug contacts. The mating ends of the second signal contacts and the second ground contacts are arranged on a second side of the receptacle slot to mate with the second plug contacts. The receptacle connector includes an outer housing having a chamber receiving the front housing. The outer housing is conductive and provides electrical shielding around the chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrical connector system having a receptacle connector in accordance with an exemplary embodiment. 
         FIG. 2  is an exploded view of the receptacle connector in accordance with an exemplary embodiment. 
         FIG. 3  is a bottom perspective, exploded view of a contact module assembly of the receptacle connector in accordance with an exemplary embodiment. 
         FIG. 4 , which is a bottom perspective view of a contact module of the contact module assembly in accordance with an exemplary embodiment. 
         FIG. 5  is a side perspective view of a ground bus insert of the contact module assembly in accordance with an exemplary embodiment. 
         FIG. 6  is an exploded, perspective view of a portion of the contact module assembly illustrating the ground bus insert between portions of the contact modules. 
         FIG. 7  is a cross-sectional view of the contact module assembly in accordance with an exemplary embodiment. 
         FIG. 8  is a bottom perspective view of a portion of the receptacle connector illustrating the contact module assembly poised for loading into a front housing of the receptacle connector. 
         FIG. 9  is a bottom perspective view of the receptacle connector showing the front housing and the contact module assembly being loaded into an outer housing of the receptacle connector. 
         FIG. 10  is a bottom perspective view of the receptacle connector showing the front housing and the contact module assembly in the outer housing. 
         FIG. 11  is a perspective view of an electrical connector system in accordance with an exemplary embodiment. 
         FIG. 12  is an exploded view of a receptacle connector of the electrical connector system in accordance with an exemplary embodiment. 
         FIG. 13  is an exterior side view of a contact module of the receptacle connector in accordance with an exemplary embodiment. 
         FIG. 14  is an interior side view of the contact module in accordance with an exemplary embodiment. 
         FIG. 15  is an exterior side view of a contact module of the receptacle connector in accordance with an exemplary embodiment. 
         FIG. 16  is an interior side view of the contact module in accordance with an exemplary embodiment. 
         FIG. 17  is a perspective view of a ground bus insert for the contact module in accordance with an exemplary embodiment. 
         FIG. 18  is another perspective view of a ground bus insert in accordance with an exemplary embodiment. 
         FIG. 19  is a perspective view of a portion of the contact module in accordance with an exemplary embodiment. 
         FIG. 20  is a cross-sectional view of the contact module in accordance with an exemplary embodiment. 
         FIG. 21  is a bottom perspective view of a portion of the receptacle connector in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an electrical connector system  100  in accordance with an exemplary embodiment. The electrical connector system  100  includes a receptacle connector  102  and a plug connector  104 . In the illustrated embodiment, the receptacle connector  102  is mounted to a circuit board  106 ; however, the receptacle connector  102  may be provided at an end of a cable or cable bundle in an alternative embodiment. In the illustrated embodiment, the plug connector  104  is provided at an end of a cable (not shown); however, the plug connector  104  may be mounted to a circuit board in an alternative embodiment. 
     The receptacle connector  102  is used to electrically connect the plug connector  104  and the circuit board  106 . The receptacle connector  102  may transmit data signals and/or power between the plug connector  104  and the circuit board  106 . In the illustrated embodiment, the receptacle connector  102  is an orthogonal connector having the mating interface of the receptacle connector  102  oriented orthogonal to the circuit board  106 . For example, in the illustrated embodiment, the mating interface of the receptacle connector  102  is oriented vertically and the circuit board  106  is oriented horizontally. Other orientations are possible in alternative embodiments. In an exemplary embodiment, the receptacle connector  102  is a card edge connector having a receptacle slot configured to receive the plug connector  104 . Other types of receptacle connectors  102  may be used in alternative embodiments. 
     The plug connector  104  includes a plug module  110  holding a plurality of plug contacts  112 . In the illustrated embodiment, the plug module  110  includes a plug housing  114  holding a circuit card  116 . The plug module  110  has a mating end  118  and the circuit card  116  is provided at the mating end  118 . The circuit card  116  has an edge  120  extending between a first surface  122  and a second surface  124 . The plug contacts  112  are provided on the circuit card  116  at or near the edge  120 . In an exemplary embodiment, the plug contacts  112  are provided on the first surface  122  and the second surface  124 . The plug contacts  112  may be circuits of the circuit card  116 , such as including pads, traces, vias, and the like. 
       FIG. 2  is an exploded view of the receptacle connector  102  in accordance with an exemplary embodiment. The receptacle connector  102  is configured to be mounted to the circuit board  106 . In an exemplary embodiment, fasteners  130  are used to secure the receptacle connector  102  to the circuit board  106 . The fasteners  130  may pass through openings  132  and the circuit board  106 . The fasteners  130  may be threaded fasteners; however, other types of fasteners may be used to secure the receptacle connector  102  to the circuit board  106 . In an exemplary embodiment, the circuit board  106  includes a plurality of vias  134  configured to be electrically connected to contacts  140  of the receptacle connector  102 . For example, the contacts  140  may be press-fit into the vias  134 . The contacts  140  may be soldered to the vias  134  in various embodiments. In alternative embodiments, the receptacle connector  102  may be surface mounted to the circuit board  106 , such as at solder pads (not shown) on the surface of the circuit board  106 . 
     The receptacle connector  102  extends between a mating end  136  and a mounting end  138 . The contacts  140  extend between the mating end  136  and the mounting end  138  for mating with the plug connector  104  and mounted to the circuit board  106 , respectively. In the illustrated embodiment, the mating end  136  is orthogonal to the mounting end  138 . For example, the mating end  136  is provided at a front of the receptacle connector  102  and the mounting end  138  is provided at a bottom of the receptacle connector  102 . However, other orientations are possible in alternative embodiments. 
     The receptacle connector  102  includes a contact module assembly  142 , a front housing  144  received in the contact module assembly  142  and an outer housing  146  received in the front housing  144 . The front housing  144  and the contact module assembly  142  are held in the outer housing  146  for mating with the plug connector  104  and the circuit board  106 . In an exemplary embodiment, the outer housing  146  is secured to the circuit board  106  using the fasteners  130 . For example, the outer housing  146  includes mounting lugs  148  that receive the fasteners  130 . The mounting lugs  148  may have threaded openings in various embodiments. 
     In an exemplary embodiment, the outer housing  146  is manufactured from a conductive material, such as a metal material to provide electrical shielding for the receptacle connector  102 . The outer housing  146  provides electrical shielding around the contacts  140 . The outer housing  146  provides electrical shielding at the mating interface with the plug connector  104 . In an exemplary embodiment, the outer housing  146  is a diecast housing. However, the outer housing  146  may be manufactured by other processes, such as molding, conductive plating of a dielectric housing, or attaching stamped and formed shields to a plastic housing. 
     The outer housing  146  extends between a front  150  and a rear  152 . The outer housing  146  includes a first side  154  and a second side  156  extending between the front  150  and the rear  152 . The outer housing  146  includes a first end  158  and a second end  160  extending between the first side  154  and the second side  156  and extending between the front  150  and the rear  152 . In an exemplary embodiment, the first end  158  may define a top of the outer housing  146  and the second end  160  may define a bottom of the outer housing  146 . However, other orientations are possible in alternative embodiments. 
     The outer housing  146  includes a chamber  162  defined between the sides  154 ,  156  and the ends  158 ,  160 . The chamber  162  extends between the front  150  and the rear  152 . The chamber  162  receives the front housing  144  and the contact module assembly  142 . In an exemplary embodiment, the outer housing  146  includes a hood  164  at the front  150 . The hood  164  is defined by the first side  154 , the second side  156 , the first end  158  and the second end  160 . The hood  164  extends entirely circumferentially around the chamber  162 . Optionally, the hood  164  may only extend a portion of the length of the outer housing  146  between the front  150  and the rear  152 . For example, the second end  160  may be open rearward of the hood  164  in various embodiments. 
     In an exemplary embodiment, the contact module assembly  142  extends from the chamber  162  rearward from the rear  152  of the outer housing  146 . However, in alternative embodiments, the contact module assembly  142  may be contained within the chamber  162 . In an exemplary embodiment, the contacts  140  extend from the chamber  162  at the bottom for mounting to the circuit board  106 . The contact module assembly  142  and the front housing  144  are loaded into the outer housing  146  through the bottom; however, the contact module assembly  142  and the front housing  144  may be loaded into the outer housing  146  in other directions, such as being rear loaded into the outer housing  146 . The outer housing  146  is open at the front  150  to provide access to the front housing  144  and the contact module assembly  142 . For example, the receptacle connector  102  may form a receptacle slot at the mating end  136  for receiving the circuit card  116  (shown in  FIG. 1 ) of the plug connector  104 . 
       FIG. 3  is a bottom perspective, exploded view of the contact module assembly  142  of the receptacle connector  102  in accordance with an exemplary embodiment. The contact module assembly  142  includes a first contact module  200 , a second contact module  300 , and a ground bus insert  400  configured to be positioned between the first contact module  200  and the second contact module  300 . The ground bus insert  400  forms a grounding structure of the contact module assembly  142 . When assembled, the first contact module  200 , the ground bus insert  400 , and the second contact module  300  are arranged in a stacked configuration. The ground bus insert  400  is sandwiched between the first contact module  200  and the second contact module  300 . In an exemplary embodiment, the ground bus insert  400  is located within the first contact module  200  and located within the second contact module  300  such that the first and second contact modules  200 ,  300  surround or envelop the ground bus insert  400 . 
     The first contact module  200  includes a first dielectric frame  210  holding a first contact lead frame  212 . The contact lead frame  212  includes first signal contacts  214  and first ground contacts  216 . The signal contacts  214  and the ground contacts  216  are at least partially encased or enclosed in the dielectric frame  210 . For example, the dielectric frame  210  may be overmolded around the signal contacts  214  and the ground contacts  216  to form an overmolded wafer. Portions of the signal contacts  214  and the ground contacts  216  are exposed through openings  218  in the dielectric frame  210 . For example, the signal contacts  214  and the ground contacts  216  may be exposed to air for impedance control of the signals through the first contact module  200 . The ground contacts  216  may be exposed through the dielectric frame  210  for interfacing with the ground bus insert  400 . For example, the ground bus insert  400  may be electrically connected to corresponding ground contacts  216  for busing or commoning the ground contacts  216 . 
     The dielectric frame  210  has a front  220  and a rear  222 . The dielectric frame  210  has a first side  224  and a second side  226 . The dielectric frame  210  has a first end  228  and a second end  230 . Optionally, the first end  228  may define a top of the dielectric frame  210  and the second end  230  may define a bottom of the dielectric frame  210 . The first side  224  defines an inner side configured to face the second contact module  300 . The second side  226  defines an outer side facing away from the second contact module  300 . The ground bus insert  400  is coupled to the first side  224  of the dielectric frame  210 . For example, the first side  224  may have a pocket or cavity that receives a portion of the ground bus insert  400 . 
     In an exemplary embodiment, the contact lead frame  212  is stamped and formed from a metal sheet to form the signal contacts  214  and the ground contacts  216 . The ground contacts  216  may be interspersed between corresponding signal contacts  214 . For example, the ground contacts  216  and the signal contacts  214  may be arranged in an alternating sequence. In other various embodiments, the signal contacts  214  may be arranged in pairs configured to convey differential signals and the ground contacts  216  may be arranged between the pairs of signal contacts  214 . Other arrangements are possible in alternative embodiments. 
     The signal contacts  214  have transition portions  240  extending between mating ends  242  and mounting ends  244  of the signal contacts  214 . The mating ends  242  extend forward from the front  220  of the dielectric frame  210  for mating with the plug connector  104  (shown in  FIG. 1 ). For example, the mating ends  242  include spring beams  246  cantilevered forward from the front  220  of the dielectric frame  210 . The spring beams  246  are deflectable and configured for mating with the circuit card  116  (shown in  FIG. 1 ) of the plug connector  104 . Optionally, the spring beams  246  may have curved mating interfaces at or near distal ends of the spring beams  246 . The mounting ends  244  extend from the second end  230  of the dielectric frame  210 , such as in a downward direction, for mounting to the circuit board  106 . For example, the mounting ends  244  include compliant pins  248 , such as eye-of-the-needle pins, configured to be press-fit into the vias  134  (shown in  FIG. 2 ) of the circuit board  106 . Other types of mounting ends may be provided in alternative embodiments. 
     The ground contacts  216  have transition portions  250  extending between mating ends  252  and mounting ends  254  of the ground contacts  216 . The mating ends  252  extend forward from the front  220  of the dielectric frame  210  for mating with the plug connector  104  (shown in  FIG. 1 ). For example, the mating ends  252  include spring beams  256  cantilevered forward from the front  220  of the dielectric frame  210 . The spring beams  256  are deflectable and configured for mating with the circuit card  116  (shown in  FIG. 1 ) of the plug connector  104 . Optionally, the spring beams  256  may have curved mating interfaces at or near distal ends of the spring beams  256 . The mounting ends  254  extend from the second end  230  of the dielectric frame  210 , such as in a downward direction, for mounting to the circuit board  106 . For example, the mounting ends  254  include compliant pins  258 , such as eye-of-the-needle pins, configured to be press-fit into the vias  134  (shown in  FIG. 2 ) of the circuit board  106 . Other types of mounting ends may be provided in alternative embodiments. 
     With additional reference to  FIG. 4 , which is a bottom perspective view of the second contact module  300 , the second contact module  300  includes a second dielectric frame  310  holding a second contact lead frame  312 . The contact lead frame  312  includes second signal contacts  314  and second ground contacts  316 . The signal contacts  314  and the ground contacts  316  are at least partially encased or enclosed in the dielectric frame  310 . For example, the dielectric frame  310  may be overmolded around the signal contacts  314  and the ground contacts  316  to form an overmolded wafer. Portions of the signal contacts  314  and the ground contacts  316  are exposed through openings  318  in the dielectric frame  310 . For example, the signal contacts  314  and the ground contacts  316  may be exposed to air for impedance control of the signals through the second contact module  300 . The ground contacts  316  may be exposed through the dielectric frame  310  for interfacing with the ground bus insert  400 . For example, the ground bus insert  400  may be electrically connected to corresponding ground contacts  316  for busing or commoning the ground contacts  316 . 
     The dielectric frame  310  has a front  320  and a rear  322 . The dielectric frame  310  has a first side  324  and a second side  326 . The dielectric frame  310  has a first end  328  and a second end  330 . Optionally, the first end  328  may define a top of the dielectric frame  310  and the second end  330  may define a bottom of the dielectric frame  310 . The first side  324  defines an inner side configured to face the first contact module  200 . The second side  326  defines an outer side facing away from the first contact module  200 . The ground bus insert  400  is coupled to the first side  324  of the dielectric frame  310 . For example, the first side  324  may have a pocket or cavity that receives a portion of the ground bus insert  400 . 
     In an exemplary embodiment, the contact lead frame  312  is stamped and formed from a metal sheet to form the signal contacts  314  and the ground contacts  316 . The ground contacts  316  may be interspersed between corresponding signal contacts  314 . For example, the ground contacts  316  and the signal contacts  314  may be arranged in an alternating sequence. In other various embodiments, the signal contacts  314  may be arranged in pairs configured to convey differential signals and the ground contacts  316  may be arranged between the pairs of signal contacts  314 . Other arrangements are possible in alternative embodiments. 
     The signal contacts  314  have transition portions  340  extending between mating ends  342  and mounting ends  344  of the signal contacts  314 . The mating ends  342  extend forward from the front  320  of the dielectric frame  310  for mating with the plug connector  104 . For example, the mating ends  342  include spring beams  346  cantilevered forward from the front  320  of the dielectric frame  310 . The spring beams  346  are deflectable and configured for mating with the circuit card  116  of the plug connector  104 . Optionally, the spring beams  346  may have curved mating interfaces at or near distal ends of the spring beams  346 . The mounting ends  344  extend from the first end  328  of the dielectric frame  310 , such as in a downward direction, for mounting to the circuit board  106 . For example, the mounting ends  344  include compliant pins  348 , such as eye-of-the-needle pins, configured to be press-fit into the vias  134  of the circuit board  106 . Other types of mounting ends may be provided in alternative embodiments. 
     The ground contacts  316  have transition portions  350  extending between mating ends  352  and mounting ends  354  of the ground contacts  316 . The mating ends  352  extend forward from the front  320  of the dielectric frame  310  for mating with the plug connector  104  (shown in  FIG. 1 ). For example, the mating ends  352  include spring beams  356  cantilevered forward from the front  320  of the dielectric frame  310 . The spring beams  356  are deflectable and configured for mating with the circuit card  116  (shown in  FIG. 1 ) of the plug connector  104 . Optionally, the spring beams  356  may have curved mating interfaces at or near distal ends of the spring beams  356 . The mounting ends  354  extend from the second end  330  of the dielectric frame  310 , such as in a downward direction, for mounting to the circuit board  106 . For example, the mounting ends  354  include compliant pins  358 , such as eye-of-the-needle pins, configured to be press-fit into the vias  134  (shown in  FIG. 3 ) of the circuit board  106 . Other types of mounting ends may be provided in alternative embodiments. 
     With additional reference to  FIG. 3  and to  FIG. 5 , which is a side perspective view of the ground bus insert  400 , the ground bus insert  400  includes ground conductors  402  electrically connected together. The ground conductors  402  are configured to be electrically connected to the first ground contacts  216  and the second ground contacts  316 . The ground conductors  402  electrically bus or common the first ground contacts  216  and the second ground contacts  316 . 
     In an exemplary embodiment, the ground bus insert  400  includes an insert frame  410  having a plurality of frame members  412  with openings  414  between the frame members  412 . The frame members  412  are connected by joining walls  416 . In an exemplary embodiment, the insert frame  410  is manufactured from a dielectric material, such as a plastic material. The insert frame  410  may be molded, such as by injection molding. The insert frame  410  forms a substrate or support structure for the ground conductors  402 . In an exemplary embodiment, the ground conductors  402  are provided on the frame members  412  and may be provided on the joining walls  416 . For example, the ground conductors  402  may be plated on the frame members  412 . The ground conductors  402  may be formed by laser direct structuring the ground conductors  402  in position on the frame members  412 . The ground conductors  402  may be electroplated. The ground conductors  402  may be applied by other processes in alternative embodiments, such as coating, dipping, spraying, and the like. 
     The insert frame  410  extends between a front  420  and a rear  422 . The insert frame  410  includes a first side  424  and a second side  426 . The insert frame  410  includes a first end  428  and a second end  430 . Optionally, the first end  428  may be a top end and the second end  430  may be a bottom end. However, other orientations are possible in alternative embodiments. The insert frame  410  includes end walls  432  extending between the first and second sides  424 ,  426 . The end walls  432  may be upper end walls generally facing in an upward direction or lower end walls generally facing in a downward direction. 
     In various embodiments, the insert frame  410  has the openings  414  between the joining walls  416 . The insert frame  410  includes first tabs  440  extending between the joining walls  416  and the first side  424 . First pockets  442  are defined between the corresponding tabs  440  and extend between the first side  424  and the joining walls  416 . In an exemplary embodiment, the first tabs  440  are configured to be received in the first dielectric frame  210  ( FIG. 3 ). The insert frame  410  includes second tabs  450  extending between the joining walls  416  and the second side  426 . Second pockets  452  are defined between the corresponding tabs  450  and extend between the second side  426  and the joining walls  416 . In an exemplary embodiment, the second tabs  450  are configured to be received in the second dielectric frame  310  ( FIG. 4 ). 
     The ground conductors  402  are provided on the exterior of the frame members  412 . For example, the ground conductors  402  may be attached to or applied directly on exterior surfaces of the frame members  412 . The ground conductors  402  may also be applied to the first tabs  440  and/or the second tabs  450  and/or the end walls  432  and/or the joining walls  416 . In an exemplary embodiment, the ground conductors  402  are provided on the first tabs  440  at the first side  424  to form first side rails  460  configured to electrically connect with corresponding first ground contacts  216  of the first contact module  200 . For example, the first side rails  460  may directly engage corresponding first ground contacts  216 . In an exemplary embodiment, the ground conductors  402  are provided on the second tabs  450  at the second side  426  to form second side rails  462  along the second tabs  450  configured to electrically connect with corresponding second ground contacts  316  of the second contact module  300 . For example, the second side rails  462  may directly engage corresponding second ground contacts  316 . 
     In an exemplary embodiment, the ground conductors  402  include connecting rails  464  provided on the corresponding end walls  432  between the first side rails  460  and the second side rails  462 . The connecting rails  464  electrically connect the first and second side rails  460 ,  462 . As such, the first and second side rails  460 ,  462  are electrically commoned or bussed by the connecting rails  464 . In an exemplary embodiment, the ground conductors  402  include connecting rails  466  provided on corresponding joining walls  416  between corresponding end walls  432 . The connecting rails  466  electrically connect the connecting rails  464 . The connecting rails  464  provide horizontal electrical connection and the connecting rails  466  provide vertical electrical connection. 
       FIG. 6  is an exploded, perspective view of a portion of the contact module assembly  142  illustrating the ground bus insert  400  between the first contact lead frame  212  and the second contact lead frame  312 . The first dielectric frame  210  (shown in  FIG. 3 ) and the second dielectric frame  310  (shown in  FIG. 3 ) are removed for clarity to illustrate the contact lead frames  212 ,  312  relative to the ground bus insert  400 . When assembled, the side rails  460 ,  462  are configured to be electrically connected to the ground contacts  216 ,  316 , respectively. The ground bus insert  400  is sandwiched between the contact lead frames  212 ,  312  to electrically connect the ground contacts  216 ,  316 . The first and second contact lead frames  212 ,  312  are separated by a gap  480  with the contacts arranged in first and second rows on opposite sides of the gap  480 . The ground bus insert  400  is received in the gap  480 . The circuit card  116  (shown in  FIG. 1 ) is configured to be received in the gap  480 . 
       FIG. 7  is a cross-sectional view of the contact module assembly  142  in accordance with an exemplary embodiment. The ground bus insert  400  is received in the openings  218 ,  318  at the inner sides  224 ,  324  of the dielectric frames  210 ,  310 . The inner sides  224 ,  324  of the dielectric frames  210 ,  310  abut against each other such that a portion of the ground bus insert  400  is received in the first contact module  200  and another portion of the ground bus insert  400  is received in the second contact module  300 . The ground conductors  402  are used to electrically connect the first and second ground contacts  216 ,  316 . For example, the connecting rails  464  electrically connect the first and second side rails  460 ,  462 . 
     When assembled, the first tabs  440  are aligned with the first ground contacts  216 . As such, the first side rails  460  on the first tabs  440  are configured to be electrically connected to the first ground contacts  216 . In an exemplary embodiment, the first side rails  460  directly engage the first ground contacts  216 . The first pockets  442  are aligned with the first signal contacts  214 . As such, the first signal contacts  214  are electrically isolated from the ground conductors  402 . When assembled, the second tabs  450  are aligned with the second ground contacts  316 . As such, the second side rails  462  on the second tabs  450  are configured to be electrically connected to the second ground contacts  316 . In an exemplary embodiment, the second side rails  460  to directly engage the second ground contacts  316 . The second pockets  452  are aligned with the second signal contacts  314 . As such, the second signal contacts  314  are electrically isolated from the ground conductors  402 . 
       FIG. 8  is a bottom perspective view of a portion of the receptacle connector  102  illustrating the contact module assembly  142  poised for loading into the front housing  144 . The front housing  144  extends between a front  170  and a rear  172 . The front housing  144  includes a first side  174  and a second side  176  extending between the front  170  and the rear  172 . The front housing  144  includes a first end  178  and a second end  180  extending between the first side  174  and the second side  176  and extending between the front  170  and the rear  172 . In an exemplary embodiment, the first end  178  may define a top of the front housing  144  and the second end  180  may define a bottom of the front housing  144 . However, other orientations are possible in alternative embodiments. 
     The front housing  144  includes a cavity  182  defined between the sides  174 ,  176  and the ends  178 ,  180 . The cavity  182  extends between the front  170  and the rear  172 . The cavity  182  receives the contact module assembly  142 . In an exemplary embodiment, the contact module assembly  142  is configured to extend from the cavity  182  rearward from the rear  172  of the front housing  144 . However, in alternative embodiments, the contact module assembly  142  may be contained within the cavity  182 . In an exemplary embodiment, the contact module assembly  142  is loaded into the cavity  182  of the front housing  144  through the rear  172 . The front housing  144  is open at the front  170  to provide access to the contact module assembly  142 . In an exemplary embodiment, the front housing  144  has a receptacle slot  184  at the front  170  for receiving the circuit card  116  (shown in  FIG. 1 ) of the plug connector  104 . 
     The mating ends  242 ,  342  of the signal contacts  214 ,  314  and the mating ends  252 ,  352  of the ground contacts  216 ,  316  extend forward of the dielectric frames  210 ,  310  into the front housing  144 . The mating ends  242 ,  342 ,  252 ,  352  are positioned in the receptacle slot  184  for mating with the circuit card  116  (shown in  FIG. 1 ). The mating ends  242 ,  252  are arranged in a first row and the mating ends  342 ,  352  are arranged in a second row on opposite sides of the receptacle slot  184  for mating with opposite sides of the circuit card  116 . 
       FIG. 9  is a bottom perspective view of the receptacle connector  102  showing the front housing  144  and the contact module assembly  142  being loaded into the outer housing  146 . In an exemplary embodiment, the outer housing  146  includes a loading slot  166  open at the second end  160  of the outer housing  146 . The loading slot  166  is located rearward of the hood  164 . The loading slot  166  receives the front housing  144 . In an exemplary embodiment, the loading slot  166  has a shoulder  168  at a rear of loading slot  166 . The shoulder  168  defines a stop surface for the front housing  144  to guide the front housing  144  into the chamber  162 . Once the front housing  144  and the contact module assembly  142  are loaded through the loading slot  166  in the loading direction into the chamber  162  to a loaded position, the front housing  144  and the contact module assembly  142  may be shifted forward to a mating position. For example, the front housing  144  may be loaded into the hood  164 . The front housing  144  and the contact module assembly  142  are configured for mating with the plug connector  104  (shown in  FIG. 1 ) in the mating position. 
       FIG. 10  is a bottom perspective view of the receptacle connector  102  showing the front housing  144  and the contact module assembly  142  in the mating position within the outer housing  146 . The front housing  144  is located in the hood  164 . In an exemplary embodiment, the front housing  144  includes a locating tab  186  at the second end  180 . The locating tab  186  is configured to engage the outer housing  146  to locate the front housing  144  relative to the outer housing  146 . For example, the locating tab  186  engages the hood  164  to position the front housing  144  in the outer housing  146 . Optionally, in the mating position, the front  170  of the front housing  144  may be generally flush with the front  150  of the outer housing  146 . The front housing  144  is located within the chamber  162  to receive the circuit card  116  of the plug connector  104  when the plug connector  104  is mated with the receptacle connector  102 . For example, the receptacle slot  184  is accessible at the mating end  136  of the receptacle connector  102  to receive the circuit card  116 . 
       FIG. 11  is a perspective view of an electrical connector system  500  in accordance with an exemplary embodiment. The electrical connector system  500  includes a receptacle connector  502  and a plug connector  504 . The receptacle connector  502  may be similar to the receptacle connector  102  shown in  FIG. 1 . The plug connector  504  may be similar to the plug connector  104  shown in  FIG. 1 . In the illustrated embodiment, the receptacle connector  502  is mounted to a circuit board  506 ; however, the receptacle connector  502  may be provided at an end of a cable or cable bundle in an alternative embodiment. 
     The receptacle connector  502  is used to electrically connect the plug connector  504  and the circuit board  506 . The receptacle connector  502  may transmit data signals and/or power between the plug connector  504  and the circuit board  506 . In the illustrated embodiment, the receptacle connector  502  is an orthogonal connector having the mating interface of the receptacle connector  502  oriented orthogonal to the circuit board  506 . For example, in the illustrated embodiment, the mating interface of the receptacle connector  502  is oriented vertically and the circuit board  506  is oriented horizontally. Other orientations are possible in alternative embodiments. In an exemplary embodiment, the receptacle connector  502  is a card edge connector having a receptacle slot configured to receive the plug connector  504 . Other types of receptacle connectors  502  may be used in alternative embodiments. 
     The plug connector  504  includes a plug module  510  holding a plurality of plug contacts  512 . In the illustrated embodiment, the plug module  510  includes a plug housing  514  holding a circuit card  516 . The plug module  510  has a mating end  518  and the circuit card  516  is provided at the mating end  518 . The circuit card  516  has an edge  520  extending between a first surface  522  and a second surface  524 . The plug contacts  512  are provided on the circuit card  516  at or near the edge  520 . In an exemplary embodiment, the plug contacts  512  are provided on the first surface  522  and the second surface  524 . The plug contacts  512  may be circuits of the circuit card  516 , such as including pads, traces, vias, and the like. 
       FIG. 12  is an exploded view of the receptacle connector  502  in accordance with an exemplary embodiment. The receptacle connector  502  is configured to be mounted to the circuit board  506 . In an exemplary embodiment, fasteners  530  are used to secure the receptacle connector  502  to the circuit board  506 . The fasteners  530  may pass through openings  532  and the circuit board  506 . The fasteners  530  may be threaded fasteners; however, other types of fasteners may be used to secure the receptacle connector  502  to the circuit board  506 . In an exemplary embodiment, the circuit board  506  includes a plurality of vias  534  configured to be electrically connected to contacts  540  of the receptacle connector  502 . For example, the contacts  540  may be press-fit into the vias  534 . The contacts  540  may be soldered to the vias  534  in various embodiments. In alternative embodiments, the receptacle connector  502  may be surface mounted to the circuit board  506 , such as at solder pads (not shown) on the surface of the circuit board  506 . 
     The receptacle connector  502  extends between a mating end  536  and a mounting end  538 . The contacts  540  extend between the mating end  536  and the mounting end  538  for mating with the plug connector  504  and mounted to the circuit board  506 , respectively. In the illustrated embodiment, the mating end  536  is orthogonal to the mounting end  538 . For example, the mating end  536  is provided at a front of the receptacle connector  502  and the mounting end  538  is provided at a bottom of the receptacle connector  502 . However, other orientations are possible in alternative embodiments. 
     The receptacle connector  502  includes a contact module assembly  542 , a front housing  544  received in the contact module assembly  542  and an outer housing  546  received in the front housing  544 . The front housing  544  and the contact module assembly  542  are held in the outer housing  546  for mating with the plug connector  504  and the circuit board  506 . In an exemplary embodiment, the outer housing  546  is secured to the circuit board  506  using the fasteners  530 . For example, the outer housing  546  includes mounting lugs  548  that receive the fasteners  530 . The mounting lugs  548  may have threaded openings in various embodiments. 
     In an exemplary embodiment, the outer housing  546  is manufactured from a conductive material, such as a metal material to provide electrical shielding for the receptacle connector  502 . The outer housing  546  provides electrical shielding around the contacts  540 . The outer housing  546  provides electrical shielding at the mating interface with the plug connector  504 . In an exemplary embodiment, the outer housing  546  is a diecast housing. However, the outer housing  546  may be manufactured by other processes, such as molding, conductive plating of a dielectric housing, or attaching stamped and formed shields to a plastic housing. 
     The outer housing  546  extends between a front  550  and a rear  552 . The outer housing  546  includes a first side  554  and a second side  556  extending between the front  550  and the rear  552 . The outer housing  546  includes a first end  558  and a second end  560  extending between the first side  554  and the second side  556  and extending between the front  550  and the rear  552 . In an exemplary embodiment, the first end  558  may define a top of the outer housing  546  and the second end  560  may define a bottom of the outer housing  546 . However, other orientations are possible in alternative embodiments. 
     The outer housing  546  includes a chamber  562  defined between the sides  554 ,  556  and the ends  558 ,  560 . The chamber  562  extends between the front  550  and the rear  552 . The chamber  562  receives the front housing  544  and the contact module assembly  542 . In an exemplary embodiment, the outer housing  546  includes a hood  564  at the front  550 . The hood  564  is defined by the first side  554 , the second side  556 , the first end  558  and the second end  560 . The hood  564  extends entirely circumferentially around the chamber  562 . Optionally, the hood  564  may only extend a portion of the length of the outer housing  546  between the front  550  and the rear  552 . For example, the second end  560  may be open rearward of the hood  564  in various embodiments. 
     In an exemplary embodiment, the contact module assembly  542  extends from the chamber  562  rearward from the rear  552  of the outer housing  546 . However, in alternative embodiments, the contact module assembly  542  may be contained within the chamber  562 . In an exemplary embodiment, the contacts  540  extend from the chamber  562  at the bottom for mounting to the circuit board  506 . The contact module assembly  542  and the front housing  544  are loaded into the outer housing  546  through the bottom; however, the contact module assembly  542  and the front housing  544  may be loaded into the outer housing  546  in other directions, such as being rear loaded into the outer housing  546 . The outer housing  546  is open at the front  550  to provide access to the front housing  544  and the contact module assembly  542 . For example, the receptacle connector  502  may form a receptacle slot at the mating end  536  for receiving the circuit card  516  (shown in  FIG. 11 ) of the plug connector  504 . 
     The contact module assembly  542  includes a first contact module  600 , a second contact module  700 , and a ground bus insert  800  ( FIGS. 17 and 18 ) configured to be positioned between the first contact module  600  and the second contact module  700 . The ground bus insert  800  forms a grounding structure of the contact module assembly  542 . When assembled, the first contact module  600 , the ground bus insert  800 , and the second contact module  700  are arranged in a stacked configuration. The ground bus insert  800  is sandwiched between the first contact module  600  and the second contact module  700 . In an exemplary embodiment, the ground bus insert  800  is located within the first contact module  600  and located within the second contact module  700  such that the first and second contact modules  600 ,  700  surround or envelop the ground bus insert  800 . 
       FIG. 13  is an exterior side view of the first contact module  600  in accordance with an exemplary embodiment.  FIG. 14  is an interior side view of the first contact module  600  in accordance with an exemplary embodiment. The first contact module  600  includes a first dielectric frame  610  holding a first contact lead frame  612 . The contact lead frame  612  includes first signal contacts  614  and first ground contacts  616 . The signal contacts  614  and the ground contacts  616  are at least partially encased or enclosed in the dielectric frame  610 . For example, the dielectric frame  610  may be overmolded around the signal contacts  614  and the ground contacts  616  to form an overmolded wafer. Portions of the signal contacts  614  and the ground contacts  616  are exposed through openings  618  in the dielectric frame  610 . The openings  618  may be provided at the interior side and/or the exterior side of the dielectric frame  610 . In various embodiments, the signal contacts  614  and the ground contacts  616  may be exposed to air for impedance control of the signals through the first contact module  600 . The ground contacts  616  may be exposed through the dielectric frame  610  for interfacing with the ground bus insert  800 . For example, the ground bus insert  800  ( FIG. 17 ) may be electrically connected to corresponding ground contacts  616  for busing or commoning the ground contacts  616 . 
     The dielectric frame  610  has a front  620  and a rear  622 . The dielectric frame  610  has a first side  624  and a second side  626 . The dielectric frame  610  has a first end  628  and a second end  630 . Optionally, the first end  628  may define a top of the dielectric frame  610  and the second end  630  may define a bottom of the dielectric frame  610 . The first side  624  defines an inner side configured to face the second contact module  700  ( FIGS. 15 and 16 ). The second side  626  defines an outer side facing away from the second contact module  700 . The ground bus insert  800  is coupled to the first side  624  of the dielectric frame  610 . For example, the first side  624  includes a pocket or cavity  632  that receives a portion of the ground bus insert  800 . 
     In an exemplary embodiment, the contact lead frame  612  is stamped and formed from a metal sheet to form the signal contacts  614  and the ground contacts  616 . The ground contacts  616  may be interspersed between corresponding signal contacts  614 . For example, the ground contacts  616  and the signal contacts  614  may be arranged in an alternating sequence. In other various embodiments, the signal contacts  614  may be arranged in pairs configured to convey differential signals and the ground contacts  616  may be arranged between the pairs of signal contacts  614 . Other arrangements are possible in alternative embodiments. 
     The signal contacts  614  have transition portions  640  extending between mating ends  642  and mounting ends  644  of the signal contacts  614 . The mating ends  642  extend forward from the front  620  of the dielectric frame  610  for mating with the plug connector  504  (shown in  FIG. 11 ). For example, the mating ends  642  include spring beams  646  cantilevered forward from the front  620  of the dielectric frame  610 . The spring beams  646  are deflectable and configured for mating with the circuit card  516  (shown in  FIG. 11 ) of the plug connector  504 . Optionally, the spring beams  646  may have curved mating interfaces at or near distal ends of the spring beams  646 . The mounting ends  644  extend from the second end  630  of the dielectric frame  610 , such as in a downward direction, for mounting to the circuit board  506 . For example, the mounting ends  644  include compliant pins  648 , such as eye-of-the-needle pins, configured to be press-fit into the vias  534  (shown in  FIG. 12 ) of the circuit board  506 . Other types of mounting ends may be provided in alternative embodiments. 
     The ground contacts  616  have transition portions  650  extending between mating ends  652  and mounting ends  654  of the ground contacts  616 . The mating ends  652  extend forward from the front  620  of the dielectric frame  610  for mating with the plug connector  504  (shown in  FIG. 11 ). For example, the mating ends  652  include spring beams  656  cantilevered forward from the front  620  of the dielectric frame  610 . The spring beams  656  are deflectable and configured for mating with the circuit card  516  (shown in  FIG. 11 ) of the plug connector  504 . Optionally, the spring beams  656  may have curved mating interfaces at or near distal ends of the spring beams  656 . The mounting ends  654  extend from the second end  630  of the dielectric frame  610 , such as in a downward direction, for mounting to the circuit board  506 . For example, the mounting ends  654  include compliant pins  658 , such as eye-of-the-needle pins, configured to be press-fit into the vias  534  (shown in  FIG. 12 ) of the circuit board  506 . Other types of mounting ends may be provided in alternative embodiments. 
       FIG. 15  is an exterior side view of the second contact module  700  in accordance with an exemplary embodiment.  FIG. 16  is an interior side view of the second contact module  700  in accordance with an exemplary embodiment. The second contact module  700  includes a second dielectric frame  710  holding a second contact lead frame  712 . The contact lead frame  712  includes second signal contacts  714  and second ground contacts  716 . The signal contacts  714  and the ground contacts  716  are at least partially encased or enclosed in the dielectric frame  710 . For example, the dielectric frame  710  may be overmolded around the signal contacts  714  and the ground contacts  716  to form an overmolded wafer. Portions of the signal contacts  714  and the ground contacts  716  are exposed through openings  718  in the dielectric frame  710 . For example, the signal contacts  714  and the ground contacts  716  may be exposed to air for impedance control of the signals through the second contact module  700 . The ground contacts  716  may be exposed through the dielectric frame  710  for interfacing with the ground bus insert  800 . For example, the ground bus insert  800  ( FIG. 17 ) may be electrically connected to corresponding ground contacts  716  for busing or commoning the ground contacts  716 . 
     The dielectric frame  710  has a front  720  and a rear  722 . The dielectric frame  710  has a first side  724  and a second side  726 . The dielectric frame  710  has a first end  728  and a second end  730 . Optionally, the first end  728  may define a top of the dielectric frame  710  and the second end  730  may define a bottom of the dielectric frame  710 . The first side  724  defines an inner side configured to face the first contact module  600 . The second side  726  defines an outer side facing away from the first contact module  600 . The ground bus insert  800  is coupled to the first side  724  of the dielectric frame  710 . For example, the first side  724  includes a pocket or cavity  732  that receives a portion of the ground bus insert  800 . 
     In an exemplary embodiment, the contact lead frame  712  is stamped and formed from a metal sheet to form the signal contacts  714  and the ground contacts  716 . The ground contacts  716  may be interspersed between corresponding signal contacts  714 . For example, the ground contacts  716  and the signal contacts  714  may be arranged in an alternating sequence. In other various embodiments, the signal contacts  714  may be arranged in pairs configured to convey differential signals and the ground contacts  716  may be arranged between the pairs of signal contacts  714 . Other arrangements are possible in alternative embodiments. 
     The signal contacts  714  have transition portions  740  extending between mating ends  742  and mounting ends  744  of the signal contacts  714 . The mating ends  742  extend forward from the front  720  of the dielectric frame  710  for mating with the plug connector  504  (shown in  FIG. 11 ). For example, the mating ends  742  include spring beams  746  cantilevered forward from the front  720  of the dielectric frame  710 . The spring beams  746  are deflectable and configured for mating with the circuit card  516  (shown in  FIG. 11 ) of the plug connector  504 . Optionally, the spring beams  746  may have curved mating interfaces at or near distal ends of the spring beams  746 . The mounting ends  744  extend from the first end  728  of the dielectric frame  710 , such as in a downward direction, for mounting to the circuit board  506 . For example, the mounting ends  744  include compliant pins  748 , such as eye-of-the-needle pins, configured to be press-fit into the vias  534  (shown in  FIG. 12 ) of the circuit board  506 . Other types of mounting ends may be provided in alternative embodiments. 
     The ground contacts  716  have transition portions  750  extending between mating ends  752  and mounting ends  754  of the ground contacts  716 . The mating ends  752  extend forward from the front  720  of the dielectric frame  710  for mating with the plug connector  504 . For example, the mating ends  752  include spring beams  756  cantilevered forward from the front  720  of the dielectric frame  710 . The spring beams  756  are deflectable and configured for mating with the circuit card  516  of the plug connector  504 . Optionally, the spring beams  756  may have curved mating interfaces at or near distal ends of the spring beams  756 . The mounting ends  754  extend from the second end  730  of the dielectric frame  710 , such as in a downward direction, for mounting to the circuit board  506 . For example, the mounting ends  754  include compliant pins  758 , such as eye-of-the-needle pins, configured to be press-fit into the vias  534  of the circuit board  506 . Other types of mounting ends may be provided in alternative embodiments. 
       FIG. 17  is a perspective view of the ground bus insert  800  in accordance with an exemplary embodiment.  FIG. 18  is another perspective view of the ground bus insert  800  in accordance with an exemplary embodiment. The ground bus insert  800  includes ground conductors  802  electrically connected together. The ground conductors  802  are configured to be electrically connected to the first ground contacts  616  ( FIGS. 13 and 14 ) and the second ground contacts  716  ( FIGS. 15 and 16 ). The ground conductors  802  electrically bus or common the first ground contacts  616  and the second ground contacts  716 . 
     In an exemplary embodiment, the ground bus insert  800  includes an insert frame  810  having a plurality of frame members  812 . In various embodiments, the frame members  812  may include openings (not shown). In other various embodiments, the frame members  812  do not include openings. The frame members  812  are connected by joining walls  816 . In an exemplary embodiment, the insert frame  410  is manufactured from a dielectric material, such as a plastic material. The insert frame  410  may be molded, such as by injection molding. The insert frame  410  forms a substrate or support structure for the ground conductors  402 . In an exemplary embodiment, the ground conductors  802  are provided on the frame members  812  and may be provided on the joining walls  816 . For example, the ground conductors  802  may be plated on the frame members  812 . The ground conductors  802  may be formed by laser direct structuring the ground conductors  802  in position on the frame members  812 . The ground conductors  802  may be electroplated. The ground conductors  802  may be applied by other processes in alternative embodiments, such as coating, dipping, spraying, and the like. 
     The insert frame  810  extends between a front  820  and a rear  822 . The insert frame  810  includes a first side  824  ( FIG. 17 ) and a second side  826  ( FIG. 18 ). The insert frame  810  includes a first end  828  and a second end  830 . Optionally, the first end  828  may be a top end and the second end  830  may be a bottom end. However, other orientations are possible in alternative embodiments. The insert frame  810  includes end walls  832  extending between the first and second sides  824 ,  826 . The end walls  832  may be upper end walls generally facing in an upward direction or lower end walls generally facing in a downward direction. 
     The insert frame  810  includes first tabs  840  extending between the joining walls  816  and the first side  824 . First pockets  842  are defined between the corresponding tabs  840  and extend between the first side  824  and the joining walls  816 . In an exemplary embodiment, the first tabs  840  are configured to be received in the first dielectric frame  610  ( FIG. 14 ). The insert frame  810  includes second tabs  850  extending between the joining walls  816  and the second side  826 . Second pockets  852  are defined between the corresponding tabs  850  and extend between the second side  826  and the joining walls  816 . In an exemplary embodiment, the second tabs  850  are configured to be received in the second dielectric frame  710  ( FIG. 16 ). Optionally, the insert frame  810  may include protrusions or interference bumps along the first tabs  840  and/or the second tabs  850  for interfacing with corresponding ground contacts of the first and second leadframes. 
     The ground conductors  802  are provided on an exterior of the frame members  812 . For example, the ground conductors  802  may be attached to or applied directly to exterior surfaces of the frame members  812 . The ground conductors  802  may be applied to the first tabs  840  and/or the second tabs  850  and/or the end walls  832  and/or the joining walls  816 . In an exemplary embodiment, the ground conductors  802  are provided on the first tabs  840  at the first side  824  to form first side rails  860  configured to electrically connect with corresponding first ground contacts  616  of the first contact module  600 . For example, the first side rails  860  may directly engage corresponding first ground contacts  616 . In an exemplary embodiment, the ground conductors  802  are provided on the second tabs  850  at the second side  826  to form second side rails  862  configured to electrically connect with corresponding second ground contacts  716  of the second contact module  700 . For example, the second side rails  862  may directly engage corresponding second ground contacts  716 . 
     In an exemplary embodiment, the ground conductors  802  include connecting rails  864  provided on the corresponding end walls  832  between the first side rails  860  and the second side rails  862 . The connecting rails  864  electrically connect the first and second side rails  860 ,  862 . As such, the first and second side rails  860 ,  862  are electrically commoned or bussed by the connecting rails  864 . In an exemplary embodiment, the ground conductors  802  include connecting rails  866  provided on corresponding joining walls  816  between corresponding end walls  832 . The connecting rails  866  electrically connect the connecting rails  864 . The connecting rails  864  provide horizontal electrical connection and the connecting rails  866  provide vertical electrical connection. 
       FIG. 19  is a perspective view of a portion of the contact module assembly  542  illustrating the ground bus insert  800  between the first contact lead frame  612  and the second contact lead frame  712 . The first dielectric frame  610  (shown in  FIGS. 13 and 14 ) and the second dielectric frame  710  (shown in  FIGS. 15 and 16 ) are removed for clarity to illustrate the contact lead frames  612 ,  712  relative to the ground bus insert  800 . When assembled, the side rails  860 ,  862  are configured to be electrically connected to the ground contacts  616 ,  716 , respectively. The ground bus insert  800  is sandwiched between the contact lead frames  612 ,  712  to electrically connect the ground contacts  616 ,  716 . The first and second contact lead frames  612 ,  712  are separated by a gap  880  with the contacts arranged in first and second rows on opposite sides of the gap  880 . The ground bus insert  800  is received in the gap  880 . The circuit card  516  (shown in  FIG. 11 ) is configured to be received in the gap  880 . 
       FIG. 20  is a cross-sectional view of the contact module assembly  542  in accordance with an exemplary embodiment. The ground bus insert  800  is received in the cavities  632 ,  732  at the inner sides  624 ,  724  of the dielectric frames  610 ,  710 . The inner sides  624 ,  724  of the dielectric frames  610 ,  710  abut against each other such that a portion of the ground bus insert  800  is received in the first contact module  600  and another portion of the ground bus insert  800  is received in the second contact module  700 . The ground conductors  802  are used to electrically connect the first and second ground contacts  616 ,  716 . For example, the connecting rails  864 ,  866  electrically connect the first and second side rails  860 ,  862 . 
     When assembled, the first tabs  840  are aligned with the first ground contacts  616 . As such, the first side rails  860  on the first tabs  840  are configured to be electrically connected to the first ground contacts  616 . In an exemplary embodiment, the first side rails  860  directly engage the first ground contacts  616 . The first pockets  842  are aligned with the first signal contacts  614 . As such, the first signal contacts  614  are electrically isolated from the ground conductors  802 . When assembled, the second tabs  850  are aligned with the second ground contacts  716 . As such, the second side rails  862  on the second tabs  850  are configured to be electrically connected to the second ground contacts  716 . In an exemplary embodiment, the second side rails  860  to directly engage the second ground contacts  716 . The second pockets  852  are aligned with the second signal contacts  714 . As such, the second signal contacts  714  are electrically isolated from the ground conductors  802 . 
       FIG. 21  is a bottom perspective view of a portion of the receptacle connector  502  illustrating the contact module assembly  542  coupled to the front housing  544  and poised for loading into the outer housing  546 . The front housing  544  extends between a front  570  and a rear  572 . The front housing  544  includes a first side  574  and a second side  576  extending between the front  570  and the rear  572 . The front housing  544  includes a first end  578  and a second end  580  extending between the first side  574  and the second side  576  and extending between the front  570  and the rear  572 . In an exemplary embodiment, the first end  578  may define a top of the front housing  544  and the second end  580  may define a bottom of the front housing  544 . However, other orientations are possible in alternative embodiments. 
     The front housing  544  includes a cavity  582  defined between the sides  574 ,  576  and the ends  578 ,  580 . The cavity  582  extends between the front  570  and the rear  572 . The cavity  582  receives the contact module assembly  542 . In an exemplary embodiment, the contact module assembly  542  is configured to extend from the cavity  582  rearward from the rear  572  of the front housing  544 . However, in alternative embodiments, the contact module assembly  542  may be contained within the cavity  582 . In an exemplary embodiment, the contact module assembly  542  is loaded into the cavity  582  of the front housing  544  through the rear  572 . The front housing  544  is open at the front  570  to provide access to the contact module assembly  542 . In various embodiments, the front housing  544  has a receptacle slot (not shown) at the front  570  for receiving the circuit card  516  (shown in  FIG. 11 ) of the plug connector  504 . 
     In an exemplary embodiment, the outer housing  546  includes a loading slot  566  open at the second end  560  of the outer housing  546 . The loading slot  566  is located rearward of the hood  564 . The loading slot  566  receives the front housing  544 . Once the front housing  544  and the contact module assembly  542  are loaded through the loading slot  566  in the loading direction into the chamber  562  to a loaded position, the front housing  544  and the contact module assembly  542  may be shifted forward to a mating position. For example, the front housing  544  may be loaded into the hood  564 . The front housing  544  and the contact module assembly  542  are configured for mating with the plug connector  504  (shown in  FIG. 5 ) in the mating position. 
     In an exemplary embodiment, the front housing  544  includes a locating tab  586  at the second end  580 . The locating tab  586  is configured to engage the outer housing  546  to locate the front housing  544  relative to the outer housing  546 . For example, the locating tab  586  engages the hood  564  to position the front housing  544  in the outer housing  546 . Optionally, in the mating position, the front  570  of the front housing  544  may be generally flush with the front  550  of the outer housing  546 . The front housing  544  is located within the chamber  562  to receive the circuit card  516  of the plug connector  504  when the plug connector  504  is mated with the receptacle connector  502 . 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.