Patent Publication Number: US-2015064968-A1

Title: Receptacle assembly having a plurality of termination points

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to receptacle assemblies having a shielding structure with a plurality of termination points. 
     Some electrical systems utilize electrical connectors to interconnect two circuit boards, such as a motherboard and daughtercard. In some systems, to electrically connect the electrical connectors, a midplane circuit board is provided with front and rear header connectors on opposed front and rear sides of the midplane circuit board. Other systems electrically connect the circuit boards without the use of a midplane circuit board by directly connecting electrical connectors on the circuit boards. 
     However, as speed and performance demands increase, known electrical connectors are proving to be insufficient. Signal loss and/or signal degradation is a problem in known electrical systems. Additionally, there is a desire to increase the density of electrical connectors to increase throughput of the electrical system, without an appreciable increase in size of the electrical connectors, and in some cases, with a decrease in size of the electrical connectors. Such increase in density and/or reduction in size causes further strains on performance. 
     In order to address performance, some known systems utilize shielding to reduce interference between the contacts of the electrical connectors. However, the shielding utilized in known systems is not without disadvantages. For instance, the shielding along the signal channels may be subject to ground induced noise resonances, particularly at higher frequencies. In the presence of isolated ground structures, such ground induced noise resonances lead to pair-to-pair crosstalk. 
     A need remains for an electrical system that provides efficient shielding to meet particular performance demands. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a receptacle assembly is provided that includes a contact module having a conductive holder and a frame assembly held by the conductive holder. The conductive holder has a first holder member and second holder member coupled to the first holder member. The conductive holder has a chamber between the first and second holder members divided into a plurality of channels by first tabs of the first holder member and second tabs of the second holder member. The first tabs have posts extending therefrom and the second tabs have holes receiving the posts of the first tabs. Each post has a plurality of termination points with the corresponding tab. The first and second holder members are electrically connected to one another at the termination points. The frame assembly includes at least one dielectric frame received in the first and second holder members. Each dielectric frame has a plurality of contacts and frame members supporting the contacts. The contacts are routed through corresponding channels and the first and second tabs passing between corresponding frame members. 
     Optionally, the holes may be open through the second holder member with the posts extending entirely through the second holder member. The posts may be cylindrical. The holes may have a plurality of flat walls each defining termination points with a corresponding post. The posts may engage each of the flat walls of the holes to mechanically and electrically secure the first holder member to the second holder member. The holes may have a polygonal cross section. 
     Optionally, each first tab may include a plurality of posts and each second tab may include a plurality of holes. The posts may extend between frame members of the second dielectric frame. Optionally, a first subset of the posts may have cylindrical posts and a second subset of the posts may have rectangular posts. 
     Optionally, the second holder member may include a second wall with the second tabs extending toward the first holder member from the second wall. The holes may extend through the second tabs and through the second wall. The holes may be surrounded on at least two opposite sides by the second tabs. The holes may be completely surrounded on all sides by the second wall. The holes may be bounded by flat walls. The holes may have tab portions through the second tabs and wall portions through the second wall. The tab portions may be bounded by less flat walls than the wall portions. 
     Optionally, the first tabs may have a first tab thickness. Each post may have a post thickness approximately equal to the corresponding first tab thickness. The first tabs may have a first section having a first tab thickness and a second section having a second tab thickness greater than the first tab thickness. Posts extending from the second section may be thicker than posts extending from the first section. 
     Optionally, the first tabs may each include first shoulders and the second tabs may each include second shoulders. The first and second tabs may be internested such that the first and second shoulders overlap each other. Optionally, the first tabs may include holes and the second tabs include posts. The posts of the second tabs may be received in corresponding holes of the first tabs. 
     In another embodiment, a receptacle assembly is provided including a contact module having a conductive holder and a frame assembly held by the conductive holder. The conductive holder includes a first holder member and second holder member coupled to the first holder member. The first holder member has a first wall with a plurality of first tabs extending from the first wall toward the second holder member. The first tabs have inner edges facing the second holder member. The first tabs have substantially cylindrical posts extending from the inner edges. Channels are defined between each of the first tabs. The second holder member has a second wall with a plurality of second tabs extending from the second wall toward the first holder member. The second tabs have inner edges facing the first holder member. Channels are defined between each of the second tabs. The second tabs have holes defined by a plurality of flat walls. The holes receive the posts of the first tabs such that each post engages each of the flat walls of the corresponding hole at a termination point. The first and second holder members are electrically connected to one another at the termination points. The frame assembly includes at least one dielectric frame received in the first and second holder members. Each dielectric frame includes a plurality of contacts and frame members supporting the contacts. The contacts are routed through corresponding channels. The first and second tabs passing between corresponding frame members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary embodiment of an electrical connector system illustrating a receptacle assembly and a header assembly. 
         FIG. 2  is an exploded view of one of the contact modules and part of a shield structure shown in  FIG. 1 . 
         FIG. 3  illustrates one of the contact modules in an assembled state. 
         FIG. 4  is a side view of a holder member of the contact module formed in accordance with an exemplary embodiment. 
         FIG. 5  is a perspective view of the holder member. 
         FIG. 6  is a side view of another holder member formed in accordance with an exemplary embodiment. 
         FIG. 7  illustrates a portion of the holder member shown in  FIG. 4 . 
         FIG. 8  is a perspective view of a portion of the holder member shown in  FIG. 6 . 
         FIG. 9  is a front perspective view of a portion of the holder members being mated together. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an exemplary embodiment of an electrical connector system  100  illustrating a receptacle assembly  102  and a header assembly  104  that may be directly mated together. The receptacle assembly  102  and/or the header assembly  104  may be referred to hereinafter individually as a “connector assembly” or collectively as “connector assemblies”. The receptacle and header assemblies  102 ,  104  are each electrically connected to respective circuit boards  106 ,  108 . 
     A mating axis  110  extends through the receptacle and header assemblies  102 ,  104 . The receptacle and header assemblies  102 ,  104  are mated together in a direction parallel to and along the mating axis  110 . The receptacle and header assemblies  102 ,  104  are utilized to electrically connect the circuit boards  106 ,  108  to one another at a separable mating interface. In an exemplary embodiment, the circuit boards  106 ,  108  are oriented perpendicular to one another when the receptacle and header assemblies  102 ,  104  are mated. Alternative orientations of the circuit boards  106 ,  108  are possible in alternative embodiments. 
     The receptacle assembly  102  includes a front housing  120  that holds a plurality of contact modules  122 . Any number of contact modules  122  may be provided to increase the number of data channels between the circuit boards  106 ,  108 . The contact modules  122  each include a plurality of receptacle signal contacts  124  (shown in  FIG. 2 ) that are received in the front housing  120  for mating with the header assembly  104 . 
     In an exemplary embodiment, each contact module  122  has a shield structure  126  for providing electrical shielding for the receptacle signal contacts  124 . In an exemplary embodiment, the shield structure  126  is electrically connected to the header assembly  104  and/or the circuit board  106 . For example, the shield structure  126  may be electrically connected to the header assembly  104  by extensions (e.g. beams or fingers) extending from the contact modules  122  that engage the header assembly  104 . The shield structure  126  may be electrically connected to the circuit board  106  by features, such as ground pins. The shield structure  126  may provide shielding along substantially the entire length of the data channels between the circuit boards  106 ,  108 . 
     The receptacle assembly  102  includes a mating end  128  and a mounting end  130 . The receptacle signal contacts  124  are received in the front housing  120  and held therein at the mating end  128  for mating to the header assembly  104 . The receptacle signal contacts  124  are arranged in a matrix of rows and columns. Any number of receptacle signal contacts  124  may be provided in the rows and columns. The receptacle signal contacts  124  also extend to the mounting end  130  for mounting to the circuit board  106 . Optionally, the mounting end  130  may be substantially perpendicular to the mating end  128 . 
     The front housing  120  includes a plurality of signal contact openings  132  and a plurality of ground contact openings  134  at the mating end  128 . The receptacle signal contacts  124  are aligned with corresponding signal contact openings  132  for mating with corresponding header signal contacts  144  when the receptacle and header assemblies  102 ,  104  are mated. The ground contact openings  134  receive header shields  146  therein when the receptacle and header assemblies  102 ,  104  are mated. The shield structures  126  of the contact modules  122  are electrically connected with the header shields  146  to electrically common the receptacle and header assemblies  102 ,  104 . 
     The front housing  120  is manufactured from a dielectric material, such as a plastic material, and provides isolation between the signal contacts  124 ,  144  and the header shields  146  and/or shield structure  126 . The front housing  120  isolates each set of receptacle and header signal contacts  124 ,  144  from other sets of receptacle and header signal contacts  124 ,  144 . 
     The header assembly  104  includes a header housing  138  having walls  140  defining a chamber  142 . The header assembly  104  has a mating end  150  and a mounting end  152  that is mounted to the circuit board  108 . Optionally, the mounting end  152  may be substantially parallel to the mating end  150 . The receptacle assembly  102  is received in the chamber  142  through the mating end  150 . The front housing  120  engages the walls  140  to hold the receptacle assembly  102  in the chamber  142 . The header signal contacts  144  and the header shields  146  extend from a base wall  148  into the chamber  142 . The header signal contacts  144  and the header shields  146  extend through the base wall  148  and are mounted to the circuit board  108 . 
     In an exemplary embodiment, the header signal contacts  144  are arranged as differential pairs. The header shields  146  are positioned between the differential pairs to provide electrical shielding between adjacent differential pairs. In the illustrated embodiment, the header shields  146  are C-shaped and provide shielding on three sides of the corresponding pair of header signal contacts  144 . The header shields  146  have a plurality of walls, such as three planar walls  154 ,  156 ,  158 . The walls  154 ,  156 ,  158  may be integrally formed or alternatively, may be separate pieces. The wall  156  defines a center wall or top wall of the header shields  146 . The walls  154 ,  158  define side walls that extend from the center wall  156 . The header shield  146  associated with another pair of header signal contacts  144  provides shielding along the open, fourth side of the header shield  146  such that each of the pairs of signal contacts  144  is shielded from each adjacent pair in the same column and the same row. Other configurations or shapes for the header shields  146  are possible in alternative embodiments. More or less walls may be provided in alternative embodiments. The walls may be bent or angled rather than being planar. In other alternative embodiments, the header shields  146  may provide shielding for individual signal contacts  144  or sets of contacts having more than two signal contacts  144 . 
       FIG. 2  is an exploded view of one of the contact modules  122  and part of the shield structure  126 . The shield structure  126  includes a first ground shield  200  and a second ground shield  202 . The first and second ground shields  200 ,  202  electrically connect the contact module  122  to the header shields  146  (shown in  FIG. 1 ). The first and second ground shields  200 ,  202  provide multiple, redundant points of contact to the header shield  146 . The first and second ground shields  200 ,  202  provide shielding on all sides of the receptacle signal contacts  124 . 
     The contact module  122  includes a holder  214  having a first holder member  216  and a second holder member  218  that are coupled together to form the holder  214 . When the holder members  216 ,  218  are coupled together, the first and second holder members  216 ,  218  define a chamber  219  that receives receptacle signal contacts  124 . The holder members  216 ,  218  are fabricated from an electrically conductive material. For example, the holder members  216 ,  218  may be fabricated from a plastic material that has been metalized, plated or coated with a metallic layer. Alternatively, the holder members  216 ,  218  may be stamped and formed or may be die-cast from a metal material. By having the holder members  216 ,  218  fabricated from an electrically conductive material, the holder members  216 ,  218  may provide electrical shielding for the receptacle assembly  102 . When the holder members  216 ,  218  are coupled together, the holder members  216 ,  218  define at least a portion of the shield structure  126  of the receptacle assembly  102 . 
     The first and second holder members  216 ,  218  include first and second tabs  220 ,  221  extending inward toward one another from first and second walls  222 ,  223  of the holder members  216 ,  218 , respectively. The tabs  220  define channels  224  therebetween. The tabs  221  define channels  225  therebetween. The tabs  220 ,  221  define at least a portion of the shield structure  126  of the receptacle assembly  102 . When assembled, the holder members  216 ,  218  are coupled together and define a front  226  and a bottom  228  of the holder  214 . The holder members  216 ,  218  are mechanically and electrically connected at multiple, redundant points of contact within the contact module  122  to create a reliable electrical connection therebetween at regular intervals. The multiple points of contact at regular intervals reduce low frequency noise resonance effects to control near end and/or far end cross talk and improve signal performance. The intervals can be selected to reduce the noise in certain ranges or below a certain threshold. For example, the intervals may be selected to reduce noise resonance effects at below 12.5 GHz. The intervals may be selected to reduce noise resonance effects at higher frequency ranges if desired. 
     The contact module  122  includes a frame assembly  230  held by the holder  214 . The frame assembly  230  includes the receptacle signal contacts  124 . The frame assembly  230  includes a pair of dielectric frames  240 ,  242  surrounding the receptacle signal contacts  124 . In an exemplary embodiment, the receptacle signal contacts  124  are initially held together as lead frames (not shown), which are overmolded with dielectric material to form the first and second dielectric frames  240 ,  242 . Manufacturing processes other than overmolding a leadframe may be utilized to form the contact modules  122 , such as loading receptacle signal contacts  124  into a formed dielectric body. 
     The dielectric frame  240  includes a plurality of frame members  248 . Each frame member  248  is formed around a different receptacle signal contact  124 . Stated differently, each receptacle signal contact  124  extends along, and inside of, a corresponding frame member  248 . The frame members  248  encase the receptacle signal contacts  124 . The receptacle signal contacts  124  have mating portions  250  extending from the front and contact tails  252  extending from the bottom of the frame members  248 . Other configurations are possible in alternative embodiments. Inner portions or encased portions of the receptacle signal contacts  124  transition between the mating portions  250  and the contact tails  252  within the dielectric frame  240 . 
     The dielectric frame  240  includes a plurality of windows  254  extending through the dielectric frame  240  between the frame members  248 . The windows  254  separate the frame members  248  from one another. In an exemplary embodiment, the windows  254  extend entirely through the dielectric frame  240 . The windows  254  are internal of the dielectric frame  240  and located between adjacent receptacle signal contacts  124 , which are held in the frame members  248 . The windows  254  extend along lengths of the receptacle signal contacts  124  between the contact tails  252  and the mating portions  250 . Optionally, the windows  254  may extend along a majority of the length of each receptacle signal contact  124  measured between the corresponding contact tail  252  and mating portion  250 . 
     During assembly, the first dielectric frame  240  and corresponding receptacle signal contacts  124  are coupled to the first holder member  216 . The frame members  248  are received in corresponding channels  224 . The first tabs  220  are received in corresponding windows  254  such that the tabs  220  are positioned between adjacent receptacle signal contacts  124 . The tabs  220  provide electrical shielding between the receptacle signal contacts  124  on either side of the tabs  220 . 
     The second dielectric frame  242  is manufactured in a similar manner as the first dielectric frame  240  and includes similar components. The second dielectric frame  242  and corresponding receptacle signal contacts  124  are coupled to the second holder member  218  in a similar manner with the second tabs  221  extending through the windows  254  in the second dielectric frame  242 . When the first and second dielectric frames  240 ,  242  are arranged in the holder members  216 ,  218 , the receptacle signal contacts  124  are arranged as differential pairs. The tabs  220 ,  221  extend through the dielectric frames  240 ,  242  to provide shielding between the differential pairs of receptacle signal contacts  124 . The first and second tabs  220 ,  221  have multiple points of contact therebetween to ensure electrical continuity of the shield structure  126  along the entire lengths of the receptacle signal contacts  124 . 
     The holder members  216 ,  218 , which are part of the shield structure  126 , provide electrical shielding between and around respective receptacle signal contacts  124 . The holder members  216 ,  218  provide shielding from electromagnetic interference (EMI) and/or radio frequency interference (RFI). The holder members  216 ,  218  may provide shielding from other types of interference as well. The holder members  216 ,  218  provide shielding around the outside of the frames  240 ,  242  and thus around the outside of all of the receptacle signal contacts  124 , such as between pairs of receptacle signal contacts  124 , as well as between the receptacle signal contacts  124  using the tabs  220 ,  221  to control electrical characteristics, such as impedance control, cross-talk control, and the like, of the receptacle signal contacts  124 . 
     The first ground shield  200  includes a main body  260  configured to be coupled to the first wall  222  of the first holder member  216 . The ground shield  200  includes grounding beams  262  extending forward from the main body  260 . The grounding beams  262  are used to electrically connect the shield structure  126  to the corresponding header shield  146  (shown in  FIG. 1 ). In an exemplary embodiment, the first ground shield  200  is manufactured from a metal material. The ground shield  200  is a stamped and formed part with the grounding beams  262  being stamped and formed out of plane with respect to the main body  260 . 
     The second ground shield  202  includes a main body  270  configured to be coupled to the second wall  223  of the second holder member  218 . The ground shield  202  includes grounding beams  272  extending forward from the main body  270 . The grounding beams  272  are used to electrically connect the shield structure  126  to the corresponding header shield  146  (shown in  FIG. 1 ). In an exemplary embodiment, the second ground shield  202  is manufactured from a metal material. The ground shield  202  is a stamped and formed part with the grounding beams  272  being stamped and formed out of plane with respect to the main body  270 . 
       FIG. 3  illustrates one of the contact modules  122  in an assembled state. During assembly of the contact module  122 , the dielectric frames  240 ,  242  (shown in  FIG. 2 ) are received in the corresponding holder members  216 ,  218 . The holder members  216 ,  218  are coupled together and generally surround the dielectric frames  240 ,  242 . With the dielectric frames  240 ,  242  aligned adjacent one another in the holder  214 , the receptacle signal contacts  124  are aligned with one another and define contact pairs  280 . Each contact pair  280  is configured to transmit differential signals through the contact module  122 . 
     The first and second ground shields  200 ,  202  (second ground shield  202  being shown in  FIG. 2 ) are coupled to the holder  214  to provide shielding for the receptacle signal contacts  124 . The grounding beams  262 ,  272  extend along the receptacle signal contacts  124 . The first and second ground shields  200 ,  202  are configured to be electrically connected to the header shields  146  (shown in  FIG. 1 ) when the receptacle assembly  102  is coupled to the header assembly  104  (shown in  FIG. 1 ). 
       FIG. 4  is a side view of the first holder member  216  formed in accordance with an exemplary embodiment.  FIG. 5  is a perspective view of the first holder member  216 .  FIGS. 4 and 5  illustrate the first tabs  220  extending from the first wall  222  to define the corresponding channels  224 . The first tabs  220  and channels  224  transition between the front  226  and bottom  228  of the first holder member  216 . 
     In an exemplary embodiment, the first holder member  216  includes a plurality of connection features that mechanically and electrically connect the first holder member  216  to the second holder member  218  (shown in  FIG. 2 ). The multiple connection features create a reliable electrical connection between the first and second holder members  216 ,  218  to ensure that the shielding structure is electrically commoned at regular intervals to reduce the ground induced noise resonances that can be present in pair-to-pair cross talk. Having multiple electrical connections reduces the presence of isolated ground structures around the receptacle signal contacts, which may enhance the electrical performance of the receptacle assembly  102  (shown in  FIG. 1 ). 
     In an exemplary embodiment, the connection features include first posts  300  arranged at intervals along the first tabs  220  and first holes  302  arranged at intervals along the first tabs  220 . The intervals of the first post  300  and first holes  302  may not be equidistant along any particular first tab  220  or from one tab  220  to another tab  220 , but rather may be arranged at intervals that are less than a preselected maximum interval. The maximum interval is selected to reduce or eliminate frequency noise resonance effects in a particular frequency range or below a predetermined frequency, such as below 12.5 GHz. Having a shorter maximum interval generally increases the frequency below which frequency noise resonance effects are reduced. For example, further decreasing of the spacing between the connection features may reduce frequency noise resonance effects below 12.5 GHz, below 20 GHz, or below other targeted frequencies. Any desired frequency range may be targeted and the corresponding spacing between the connection features may be set accordingly. 
     The first posts  300  are configured to be received in corresponding holes  322  (shown in  FIG. 6 ) in the second holder member  218  while the first holes  302  are configured to receive corresponding posts  320  (shown in  FIG. 6 ) extending from the second holder member  218 , as described in further detailed below. The posts  300  and holes  302  may be arranged in any sequence, such as an alternating sequence of post-hole-post-hole along the first tab  220 . Other sequences are possible in alternative embodiments. 
     Optionally, in an alternative embodiment, the first holder member  216  may include only posts  300  or only holes  302 . Optionally, the first holder member  216  may include different sized and shaped posts  300  and holes  302  along the first tabs  220 . Optionally, the first holder member  216  may include connection features in locations other than along the first tabs  220 . For example, in the illustrated embodiment, the first holder member  216  includes outer posts  304  along surfaces of the first holder member  216  outside of the area of the first tabs  220 . 
     In an exemplary embodiment, the connection features include first shoulders  306  along the first tabs  220 . Each first shoulder  306  may be provided along the upper half of the corresponding first tab  220  and include a downward facing surface  308  that is configured to engage a corresponding shoulder of the second holder member  218 . The first shoulders  306  may engage the second holder member  218  to create mechanical and/or electrical connection between the first holder member  216  and the second holder member  218 . 
     Optionally, the first tabs  220  may have different thickness along different sections thereof, with the thickness dimension generally defined across the tab  220  between the adjacent channels  224  on either side of the corresponding tab  220 . For example, the first tab  220  may have a first tab thickness  312  along a first section, generally identified as  310 , while the first tab  220  may have a second tab thickness  314  along a second section, generally identified at  316 . The second tab thickness  314  may be greater than the first tab thickness  312 . The first posts  300  may have post thicknesses approximately equal to the corresponding tab thicknesses. Optionally, different subsets of the posts may have different thicknesses or diameters. For example, the first posts  300  along the first section  310  may have a first post thickness  318  approximately equal to the first tab thickness  312 . Optionally, any posts along the second tab thickness  314  may have a post thickness approximately equal to the second tab thickness  314 , thus providing two different sizes of posts. 
     Optionally, the first posts  300  may be cylindrical in shape. Alternatively, the first posts  300  may have other shapes, such as rectangular shapes. The first posts  300  may be elongated along the length of the tab  220 , with the length of the tab  220  being defined in a direction generally parallel to the channels  224 . 
       FIG. 6  is a side view of the second holder member  218  formed in accordance with an exemplary embodiment.  FIG. 6  illustrates the second tabs  221  extending from the second wall  223  to define the corresponding channels  225 . 
     In an exemplary embodiment, the second holder member  218  includes a plurality of connection features that mechanically and electrically connect the second holder member  218  to the first holder member  216  (shown in  FIGS. 4 and 5 ). The multiple connection features create a reliable electrical connection between the first and second holder members  216 ,  218  to ensure that the shielding structure is electrically commoned at regular intervals to reduce the ground induced noise resonances that can be present in pair-to-pair cross talk. Having multiple electrical connections reduces the presence of isolated ground structures around the receptacle signal contacts, which may enhance the electrical performance of the receptacle assembly  102  (shown in  FIG. 1 ). 
     In an exemplary embodiment, the connection features include second posts  320  arranged at intervals along the second tabs  221  and second holes  322  arranged at intervals along the second tabs  221 . The intervals may be selected to reduce or eliminate frequency noise resonance effects in a particular frequency range or below a predetermined frequency, such as below 12.5 GHz. Any desired frequency range may be targeted and the corresponding spacing between the connection features may be set accordingly. 
     The second posts  320  are configured to be received in corresponding first holes  302  (shown in  FIG. 4 ) in the first holder member  216  while the second holes  322  are configured to receive corresponding posts  300  (shown in  FIGS. 4 and 5 ) extending from the first holder member  216 . The posts  320  and holes  322  may be arranged in any sequence, such as an alternating sequence of post-hole-post-hole along the second tab  221 . Other sequences are possible in alternative embodiments. 
     Optionally, in an alternative embodiment, the second holder member  218  may include only posts  320  or only holes  322 . Optionally, the second holder member  218  may include different sized and shaped posts  320  and holes  322  along the second tabs  221 . Optionally, the second holder member  218  may include connection features in locations other than along the second tabs  221 . For example, in the illustrated embodiment, the second holder member  218  includes outer holes  324  along surfaces of the second holder member  218  outside of the area of the second tabs  221 . The outer holes  324  are configured to receive the outer posts  304  ( FIG. 5 ) of the first holder member  216 . 
     In an exemplary embodiment, the connection features include second shoulders  326  along the second tabs  221 . Each second shoulder  326  may be provided along the lower half of the corresponding second tab  221  and include an upward facing surface  328  that is configured to engage a corresponding first shoulder  306  (shown in  FIGS. 4 and 5 ) of the first holder member  216 . The second shoulders  326  may engage the first shoulders  306  to create mechanical and/or electrical connection between the first holder member  216  and the second holder member  218 . 
     Optionally, the second tabs  221  may have different thickness along different sections thereof, with the thickness dimension generally defined across the tab  221  between the adjacent channels  225  on either side of the corresponding tab  221 . Optionally, the second posts  320  may have post thicknesses approximately equal to the corresponding tab thicknesses. 
     Optionally, the second posts  320  may be cylindrical in shape. Alternatively, the second posts  320  may have other shapes, such as rectangular shapes. The second posts  320  may be elongated along the length of the corresponding tab  221 , with the length of the tab  221  being defined in a direction generally parallel to the channels  225 . 
       FIG. 7  illustrates a portion of the first holder member  216  showing one of the first posts  300  and one of the first holes  302 . The second posts  320  and second holes  322  (both shown in  FIG. 6 ) may be similar to the first posts  300  and first holes  302 , respectively. 
     The first tabs  220  extend inward from the first wall  222  to an inner edge  330 . The first post  300  extends from the inner edge  330 . In the illustrated embodiment, the first post  300  is cylindrical in shape. The first post  300  has a circular cross section. However, other shapes are possible in alternative embodiments. The first post  300  is sized and shaped to fit in the corresponding second hole  322  when the first holder member  216  is coupled to the second holder member  218  (shown in  FIG. 6 ). The first post  300  is an integral part of the first holder member  216  and may be co-molded or co-formed with other portions of the first holder member  216 , such as the first tab  220  and the first wall  222 . 
     The first hole  302  is sized and shaped to receive one of the second posts  320  (shown in  FIG. 6 ). In an exemplary embodiment, the first hole  302  is bounded by a plurality of flat walls  332 . Each flat wall  332  is configured to engage the corresponding second post  320  at a termination point  334 , which may be approximately centered along the flat wall  332 . Each second post  320  is configured to engage the first holder member  216  at a plurality of termination points  334  ensuring good electrical connection between the first holder member  216  and the second holder member  218 . The first hole  302  has a tab portion  336  extending through the first tab  220  and a wall portion  338  extending through the first wall  222 . 
     In the illustrated embodiment, the first holes  302  are generally hexagonal shaped, however other polygonal shaped holes may be used in alternative embodiments having a different number of flat walls  332  and/or open sides. The first hole  302  is open on at least two sides thereof (for example, two opposite sides of the hexagonal shaped hole  302 ) in the tab portion  336 . The open sides may be open to the channels  224  on both sides of the tab  220 . The tab portions  336  include four flat walls  332  defining multiple termination points  334  with the second post  320  when received therein. For example, the first holes  302 , in the tab portions  336 , are surrounded on at least two sides by the first tabs  220 . Each of the tab portions  336  on the opposite sides of the first holes  302  have at least two flat walls  332  defining termination points  334 . The wall portion  338  is bounded on all sides by flat walls  332 , such as by six flat walls  332 . 
       FIG. 8  is a perspective view of a portion of the second holder member  218  showing one of the second posts  320  and one of the holes  322 . The second tabs  221  extend inward from the second wall  223  to an inner edge  340 . The second post  320  extends from the inner edge  340 . In the illustrated embodiment, the second post  320  is cylindrical in shape. The second post  320  has a circular cross section. However, other shapes are possible in alternative embodiments. The second post  320  is sized and shaped to fit in the corresponding first hole  302  (shown in  FIG. 7 ) when the first holder member  216  (shown in  FIG. 7 ) is coupled to the second holder member  218 . The second post  320  is an integral part of the second holder member  218  and may be co-molded or co-formed with other portions of the second holder member  218 , such as the second tab  221  and the second wall  223 . 
     The second hole  322  is sized and shaped to receive one of the first posts  300  (shown in  FIG. 7 ). In an exemplary embodiment, the second hole  322  is bounded by a plurality of flat walls  342 . Each flat wall  342  is configured to engage the corresponding first post  300  at a termination point  344 , which may be approximately centered along the flat wall  342 . Each first post  320  is configured to engage the second holder member  218  at a plurality of the termination points  344  ensuring good electrical connection between the first holder member  216  and the second holder member  218 . The second hole  322  has a tab portion  346  extending through the second tab  221  and a wall portion  348  extending through the second wall  223 . 
     In the illustrated embodiment, the second hole  322  is generally hexagonal shaped, however other polygonal shaped holes may be used in alternative embodiments having a different number of flat walls  342  and/or open sides. The second hole  322  is open on at least two sides thereof (for example, two opposite sides of the hexagonal shaped hole  322 ) in the tab portion  346 . The open sides may be open to the channels  225  on both sides of the tab  221 . The tab portions  346  include four flat walls  342  defining multiple termination points  344  with the first post  300  when received therein. For example, the second hole  322 , in the tab portions  346 , is surrounded on at least two sides by the second tab  221 . Each of the tab portions  346  on the opposite sides of the second hole  322  have at least two flat walls  342  defining termination points  344 . The wall portion  348  is bounded on all sides by flat walls  342 , such as by six flat walls  342 . 
       FIG. 9  is a front perspective view of a portion of the holder  214  (shown in  FIGS. 2 and 3 ) showing the first holder member  216  and the second holder member  218  poised for mating together. While  FIGS. 7 and 8  illustrated cylindrical posts  300 ,  320  and hexagonal shaped holes  302 ,  322 , the first and second holder member  216 ,  218  may include other types of post and holes. In the illustrated embodiment, the first holder member  216  includes a rectangular shaped first post  300   a  and the second holder member  218  includes a rectangular shaped second hole  322   a  that receives the first post  300   a . The rectangular posts and holes  300   a ,  322   a  generally define a tongue and a groove interface. The posts and holes  300 ,  322  may be referred to hereinafter as a tongue  300   a  and a groove  322   a , respectively. In an exemplary embodiment, the tongue  300   a  and groove  322   a  are provided at the front  226  ( FIG. 2 ) of the holder  214 ; however the tongue  300   a  and groove  322   a  may be positioned at any location along the first and second tabs  220 ,  221 . The tongue  300   a  includes ribs  350  along both sides thereof. The ribs  350  may be crush ribs. The ribs  350  define termination points  352  that create an electrical and mechanical connection between the first holder member  216  and the second holder member  218 . The cylindrical posts  300 ,  320  may include ribs to define the termination points. 
       FIG. 9  also illustrates one of the second posts  320  being loaded into one of the first holes  302 . When the second post  320  is received in the first hole  302 , the second post  320  is positioned between the channels  224  ( FIGS. 4 and 5 ) of the first holder member  216 . The second post  320  is positioned directly between receptacle signal contacts  124  (shown in  FIG. 2 ) that are routed in the channels  224  both above and below the second post  320 . The second post  320  provides electrical shielding within the contact plane of the first dielectric frame  240  (shown in  FIG. 2 ). 
     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, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.