Patent Publication Number: US-10763622-B2

Title: Grounding structure for an electrical connector

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to grounding structures for electrical connector assemblies. 
     Electrical connector assemblies are used in communication systems for electrically connecting circuit boards. For example, some communication systems use header connector assemblies and receptacle connector assemblies to electrically connect circuit boards. Some known connector assemblies use differential pair signals along the signal paths that are electrically shielded within the connector assemblies. For example, the header connector assemblies utilize C-shaped header ground shields to provide electrical shielding for the pairs of signal contacts in the mating zone. However, at some frequencies, noise resonance is problematic at the mating interface between conventional connector assemblies. 
     A need remains for improved grounding structures for electrical connector assemblies. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical connector is provided for mating with a header connector having header signal contacts and header ground shields providing electrical shielding for the header signal contacts. The electrical connector includes a front housing having a front and a rear and a cavity at the rear with the front configured to be mated with the header connector. The electrical connector includes a contact module received in the cavity having a frame assembly including an array of signal contacts and a dielectric holder holding the array of signal contacts. Each signal contact has a mating end and a terminating end. The mating end extends into the front housing for mating with the corresponding header signal contact of the header connector and the terminating end extends from the dielectric holder for termination to a circuit board. A ground shield is coupled to the dielectric holder. The ground shield provides electrical shielding for the signal contacts. The ground shield has a mating end and a terminating end configured to be terminated to the circuit board. The ground shield has a ground pad at the mating end, mating beams extending from the ground pad for mating with corresponding header ground shields and ground beams between corresponding mating beams for mating with corresponding header ground shields. 
     In another embodiment, an electrical connector is provided for mating with a header connector having header signal contacts and header ground shields providing electrical shielding for the header signal contacts. The electrical connector includes a front housing having a front and a rear and a cavity at the rear with the front configured to be mated with the header connector. The electrical connector includes a contact module received in the cavity having a frame assembly including an array of signal contacts and a dielectric holder holding the array of signal contacts. Each signal contact has a mating end and a terminating end. The mating end extends into the front housing for mating with the corresponding header signal contact of the header connector and the terminating end extends from the dielectric holder for termination to a circuit board. A ground shield is coupled to the dielectric holder. The ground shield provides electrical shielding for the signal contacts. The ground shield has a mating end and a terminating end configured to be terminated to the circuit board. The ground shield has a ground pad at the mating end. The ground shield has mating beams extending forward from the ground pad for mating with corresponding header ground shields. The ground shield has ground beams extending forward from the ground pad between mating beams for mating with corresponding header ground shields. Each ground beam has an upper tab for mating with the header ground shield above the corresponding ground beam and a lower tab for mating with the header ground shield below the corresponding ground beam. 
     In a further embodiment, an electrical connector is provided for mating with a header connector having header signal contacts and header ground shields providing electrical shielding for the header signal contacts. The electrical connector includes a front housing having a front and a rear and a cavity at the rear with the front configured to be mated with the header connector. The electrical connector includes a contact module received in the cavity having a frame assembly including an array of signal contacts and a dielectric holder holding the array of signal contacts. Each signal contact has a mating end and a terminating end. The mating end extends into the front housing for mating with the corresponding header signal contact of the header connector and the terminating end extends from the dielectric holder for termination to a circuit board. A ground shield is coupled to the dielectric holder. The ground shield provides electrical shielding for the signal contacts. The ground shield has a mating end and a terminating end configured to be terminated to the circuit board. The ground shield has a ground pad at the mating end. The ground shield has mating beams extending forward from the ground pad for mating with interior surfaces of end walls of corresponding header ground shields. The ground shield has ground beams extending forward from the ground pad between corresponding mating beams for mating with edges of the end walls of corresponding header ground shields. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an electrical connector system formed in accordance with an exemplary embodiment. 
         FIG. 2  is a partially exploded view of a portion of an electrical connector of the electrical connector system. 
         FIG. 3  is a perspective view of a ground shield of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 4  is an exploded view of a contact module of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 5  is a perspective view of the contact module in an assembled state. 
         FIG. 6  is a perspective view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 7  is a side view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 8  is a front view of the mating interface of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 9  is a perspective view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 10  is a side view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 11  is a perspective view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 12  is a front view of a portion of the electrical connector in accordance with an exemplary embodiment. 
         FIG. 13  is a front view of the mating interface of the electrical connector in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a front perspective view of an electrical connector system  100  formed in accordance with an exemplary embodiment. The connector system  100  includes an electrical connector  102  configured to be mounted to a circuit board  104  and a mating electrical connector  106 , which may be mounted to a circuit board  108 . The mating electrical connector  106  may be a header connector and may be referred to hereinafter as a header connector  106 . Various types of connector assemblies may be used in various embodiments, such as a right angle connector, a vertical connector or another type of connector. 
     The header connector  106  includes a housing  110  holding a plurality of header signal contacts  112  and header ground shields  114 . The header signal contacts  112  may be arranged in pairs. Each header ground shield  114  extends around corresponding header signal contacts  112 , such as the pairs of header signal contacts  112 . In the illustrated embodiment, the header ground shields  114  are C-shaped having three walls including end walls  115 ,  116  and a center wall  117  between the end walls  115 ,  116 . The walls extend along three sides of each pair of header signal contacts  112 . The header ground shield  114  adjacent to the pair provides electrical shielding along a fourth side of the pair. As such, the pairs of header signal contacts  112  are circumferentially surrounded on all four sides by the header ground shields  114 . The header ground shields  114  may have other shapes in alternative embodiments. The header ground shields  114  extend to tips  118  at distal ends thereof. The end walls  115 ,  116  extend to edges  119 , such as at bottoms thereof. Interior surfaces  121  of the walls face the header signal contacts  112 . Exterior surfaces of the walls, opposite the interior surfaces, face away from the header signal contacts  112 . 
     The electrical connector  102  includes a housing  120  that holds a plurality of contact modules  122 . The contact modules  122  are held in a stacked configuration generally parallel to one another. The contact modules  122  may be loaded into the housing  120  side-by-side in the stacked configuration as a unit or group. Any number of contact modules  122  may be provided in the electrical connector  102 . The contact modules  122  each include a plurality of signal contacts  124  (shown in  FIG. 2 ) that define signal paths through the electrical connector  102 . The signal contacts  124  are configured to be electrically connected to corresponding header signal contacts  112  of the header connector  106 . 
     The electrical connector  102  includes a mating end  128 , such as at a front  129  of the electrical connector  102 , and a mounting end  130 , such as at a bottom  131  of the electrical connector  102 . In the illustrated embodiment, the mounting end  130  is oriented substantially perpendicular to the mating end  128 . The mating and mounting ends  128 ,  130  may be at different locations other than the front  129  and bottom  131  in alternative embodiments. The signal contacts  124  extend through the electrical connector  102  from the mating end  128  to the mounting end  130  for mounting to the circuit board  104 . 
     The signal contacts  124  are received in the housing  120  and held therein at the mating end  128  for electrical termination to the header connector  106 . The signal contacts  124  are arranged in a matrix of rows and columns. In the illustrated embodiment, at the mating end  128 , the rows are oriented horizontally and the columns are oriented vertically. Other orientations are possible in alternative embodiments. Any number of signal contacts  124  may be provided in the rows and columns. Optionally, the signal contacts  124  may be arranged in pairs carrying differential signals; however other signal arrangements are possible in alternative embodiments, such as single-ended applications. Optionally, the pairs of signal contacts  124  may be arranged in rows (pair-in-row signal contacts); however, the pairs of signal contacts may be arranged in columns (pair-in-column signal contacts) in alternative embodiments. In an exemplary embodiment, the signal contacts  124  within each pair are contained within the same contact module  122 . 
     In an exemplary embodiment, each contact module  122  has a shield structure  126  for providing electrical shielding for the signal contacts  124 . The shield structure  126  is configured to be electrically connected to the header ground shields  114  of the header connector  106 . The shield structure  126  may provide shielding from electromagnetic interference (EMI) and/or radio frequency interference (RFI), and may provide shielding from other types of interference as well to better control electrical characteristics, such as impedance, cross-talk, and the like, of the signal contacts  124 . The contact modules  122  provide shielding for each pair of signal contacts  124  along substantially the entire length of the signal contacts  124  between the mating end  128  and the mounting end  130 . In an exemplary embodiment, the shield structure  126  is configured to be electrically connected to the header connector  106  and/or the circuit board  104 . The shield structure  126  may be electrically connected to the circuit board  104  by features, such as grounding pins and/or surface tabs. 
     The housing  120  includes a plurality of signal contact openings  132  and a plurality of ground contact openings  134  at the mating end  128 . The signal contacts  124  are received in corresponding signal contact openings  132 . Optionally, a single signal contact  124  is received in each signal contact opening  132 . The signal contact openings  132  may also receive corresponding header signal contacts  112  of the header connector  106 . In the illustrated embodiment, the ground contact openings  134  are C-shaped extending along three sides of the corresponding pair of signal contact openings  132 . The ground contact openings  134  receive header ground shields  114  of the header connector  106 . The ground contact openings  134  also receive portions of the shield structure  126  (for example, beams and/or fingers) of the contact modules  122  that mate with the header ground shields  114  to electrically common the shield structure  126  with the header connector  106 . 
     The housing  120  is manufactured from a dielectric material, such as a plastic material, and provides isolation between the signal contact openings  132  and the ground contact openings  134 . The housing  120  isolates the signal contacts  124  from the shield structure  126 . The housing  120  isolates each set (for example, differential pair) of signal contacts  124  from other sets of signal contacts  124 . 
       FIG. 2  is a partially exploded view of a portion of the electrical connector  102  with the housing  120  removed to illustrate the contact modules  122  in accordance with an exemplary embodiment. Each contact module  122  includes a frame assembly  140  having an array of the signal contacts  124  and a dielectric holder  142  holding the signal contacts  124 . The dielectric holder  142  generally surrounds the signal contacts  124  along substantially the entire length of the signal contacts  124  between the mounting end  130  at the bottom  131  and the mating end  128  at the front  129 . The shield structure  126  is coupled to the dielectric holder  142  to provide electrical shielding for the signal contacts  124 , such as for each pair of the signal contacts  124 . The shield structure  126  provides circumferential shielding for each pair of signal contacts  124  along at least a majority of a length of the signal contacts  124 , such as substantially an entire length of the signal contacts  124 . 
     In an exemplary embodiment, the frame assembly  140  is assembled together from two contact sub-assemblies. For example, the dielectric holder  142  may be a two-piece holder formed from two dielectric bodies  144  arranged side-by-side. Each dielectric body  144  surrounds a corresponding array of signal contacts  124 . The dielectric body  144  may be overmolded over the signal contacts  124  (for example, each dielectric body  144  may be overmolded over a set of the signal contacts  124  to form one of the contact sub-assemblies). Optionally, the signal contacts  124  may be initially formed from a leadframe and overmolded by the corresponding dielectric body  144  such that portions of the signal contacts  124  are encased in the dielectric holder  142 . 
     The dielectric holder  142  has a mating end  150  at a front  151  thereof configured to be loaded into the housing  120  (shown in  FIG. 1 ), a rear  152  opposite the mating end  150 , a mounting end  154  at a bottom  155  which optionally may be adjacent to the circuit board  104  (shown in  FIG. 1 ), and a top  156  generally opposite the mounting end  154 . The dielectric holder  142  also includes first and second sides, such as a right side  160  and a left side  162 . The shield structure  126  is coupled to both the right and left sides  160 ,  162 . The dielectric bodies  144  include respective interior sides  164  facing and abutting each other. Each dielectric body  144  holds one of the signal contacts  124  from each pair such that the pair has signal contacts  124  in both contact sub-assemblies. When assembled, the signal contacts  124  in each pair are aligned with each other and follow similar paths between the mating and mounting ends  128 ,  130 . For example, the signal contacts  124  have similar shapes and thus have similar lengths, which reduces or eliminates skew in the signal paths for the pairs. The pair-in-row arrangement may enhance the electrical performance of the contact module  122  as compared to pair-in-column contact modules having the signal contacts of each pair radially offset from each other (for example, one radially inside and the other radially outside), leading to skew problems. 
     The signal contacts  124  may be stamped and formed from a sheet of metal material. Each signal contact  124  has a mating portion  166  extending forward from the mating end  150  of the dielectric holder  142  and a mounting portion  168  extending downward from the mounting end  154 . The mating and mounting portions  166 ,  168  are exposed beyond the front  151  and the bottom  155 , respectively, of the dielectric holder  142 . Each signal contact  124  has a transition portion  170  (one of which is shown in phantom in  FIG. 2 ) between the mating and mounting portions  166 ,  168 . The transition portions  170  each include a top, a bottom, a right side, and a left side (the right and left sides define corresponding inner and outer sides for the left and right contact sub-assemblies. In an exemplary embodiment, the top, bottom, and corresponding outer side are each configured to be shielded by the shield structure  126 . The inner sides (right side or left side) face each other along the lengths of the transition portions  170 . The mating portions  166  are configured to be electrically terminated to corresponding header signal contacts  112  (shown in  FIG. 1 ) when the electrical connector  102  is mated to the header connector  106  (shown in  FIG. 1 ). In an exemplary embodiment, the mounting portions  168  include compliant pins, such as eye-of-the-needle pins, configured to be terminated to the circuit board  104  (shown in  FIG. 1 ). 
     In an exemplary embodiment, the shield structure  126  includes first and second ground shields  180 ,  182  and ground blades  184  extending between and configured to be electrically connected to the first and second ground shields  180 ,  182 . Each ground blade  184  is configured to be assembled with the dielectric holder  142 , such as immediately forward of the mating end  150  of the dielectric holder  142 . The ground blade  184  may be attached to the electric holder  142  at the mating end  150 . In an exemplary embodiment, the ground blades  184  span or cover the mating ends  150  of each of the dielectric holders  142 . The ground blades  184  are oriented horizontally along the front  129  of the electrical connector  102 . The ground blades  184  are positioned adjacent to the mating zone between the signal contacts  124  and the header signal contacts  112  ( FIG. 1 ). The ground blades  184  are configured to be electrically connected to the first and second ground shields  180 ,  182  of each contact module  122  such that the ground shields  180 ,  182  are electrically commoned adjacent to the mating zone. Optionally, the ground blades  184  may be used to mechanically secure the first ground shield  180  and/or the second ground shield  182  to the contact module  122 . The ground blades  184  provide electrical shielding for the signal contacts  124  at the exit/entrance points of the signal contacts  124  from the dielectric holder  142 . The ground blades  184  provide electrical shielding for the mating portions  166  of the signal contacts  124  adjacent to the mating zone. 
     In an exemplary embodiment, the ground blades  184  are provided above and/or below each of the mating portions  166  of the pairs of signal contacts  124  to provide electrical shielding between the pairs of signal contacts  124  within the same contact module  122 . The first and second ground shields  180 ,  182  are provided along right and left sides of each of the mating portions  166  of the pairs of signal contacts  124  to provide electrical shielding between the pairs of signal contacts  124  in adjacent contact modules  122 . In an exemplary embodiment, the ground blades  184  and the first and second ground shields  180 ,  182  form shield pockets around each pair of signal contacts  124  to shield such pair from adjacent pairs in the same column and in the same row. In an exemplary embodiment, the ground blades  184  and the first and second ground shields  180 ,  182  extend across the fronts  151  of the dielectric holders  142  to provide shielding for the mating portions  166  and the transition portions  170  of the signal contacts  124 . 
     The first and second ground shields  180 ,  182  cooperate to provide circumferential shielding for each pair of signal contacts  124  along the length thereof. The first ground shield  180  is positioned along the right side  160  of the dielectric holder  142 , and as such, may be hereinafter referred to as the right ground shield  180 . The second ground shield  182  is positioned along the left side  162  of the dielectric holder  142 , and may be hereinafter referred to as the left ground shield  182 . The first and second ground shields  180 ,  182  and the ground blades  184  electrically connect the contact module  122  to the header connector  106 , such as to the header ground shields  114  thereof (shown in  FIG. 1 ), thereby providing an electrically common ground path between the electrical connector  102  and the header connector  106 . The first and second ground shields  180 ,  182  electrically connect the contact module  122  to the circuit board  104 , such as through compliant pins thereof. The first and second ground shields  180 ,  182  may be similar and include similar features and components. As such, the description below may include description of either ground shield, which may be relevant to the other ground shield, and like components may be identified with like reference numerals. 
     In an exemplary embodiment, the ground blade  184  includes a main body  185  having a front  186  and a rear  187 . The ground blade  184  includes a plurality of mating portions  188  extending forward from the front  186 . In the illustrated embodiment, the mating portions  188  are arranged in sets, with each set configured to mate with a corresponding header ground shield  114  (shown in  FIG. 1 ). Each set includes a plurality of mating portions  188 , thus defining multiple points of contact with the header ground shield  114 . The mating portions  188  are deflectable mating beams configured to be spring biased against the header ground shield  114  when mated thereto to create a mechanical and electrical connection with the header ground shield  114 . Optionally, the mating portions  188  are configured to be received inside the corresponding C-shaped header ground shields  114  of the header connector  106 . Alternatively, the mating portions  188  are configured to extend along the outside of the corresponding C-shaped header ground shields  114  of the header connector. 
     The ground blade  184  includes a mounting tab  189  extending from the rear  187 . The mounting tab  189  is used for mounting the ground blade  184  to the dielectric holder  142  (shown in  FIG. 2 ). The ground blade  184  includes slots  191  that receive the first and second ground shields  180 ,  182  during mating thereto. In an exemplary embodiment, the ground blade  184  includes a mating finger  192  extending along the slot  191 . The mating finger  192  is configured to be mated to the corresponding ground shield  180 ,  182 . Optionally, the mating finger  192  may be deflectable. 
       FIG. 3  is a perspective view of the first ground shield  180  in accordance with an exemplary embodiment. In an exemplary embodiment, the first ground shield  180  is stamped and formed from a stock piece of metal material. The first ground shield  180  includes a main body  200  configured to extend along the right side  160  of the dielectric holder  142  (both shown in  FIG. 2 ). The main body  200  includes a plurality of right side rails  202  separated by right side gaps  204 . The right side rails  202  are interconnected by struts  206  that span the gaps  204  between the right side rails  202 . 
     The first ground shield  180  includes mating beams  210  at a mating end  214  of the main body  200 . The mating beams  210  are configured to be mated with corresponding mating portions of the header connector  106  (for example, the C-shaped header ground shields  114 , shown in  FIG. 1 ). In an exemplary embodiment, the mating beams  210  are bifurcated including multiple mating beams  210  associated with each corresponding signal contact  124 . The mating beams  210  may be deflectable mating beams, such as spring beams. Optionally, the mating beams  210  are configured to be received inside the corresponding C-shaped header ground shields  114  of the header connector  106 . Alternatively, the mating beams  210  are configured to extend along the outside of the corresponding C-shaped header ground shields  114  of the header connector. 
     The first ground shield  180  includes mounting portions  216  defined by compliant pins  218  at a mounting end  220  of the main body  200 . The mounting portions  216  are configured to be terminated to the circuit board  104  (shown in  FIG. 1 ). For example, the mounting portions  216  are configured to be received in plated vias in the circuit board  104 . 
     The right side rails  202  are configured to provide shielding around corresponding signal contacts  124  (shown in  FIG. 2 ). For example, in an exemplary embodiment, the right side rails  202  have side strips  222  configured to extend along the right side  160  of the dielectric holder  142 , and connecting strips  224  configured to extend into the dielectric holder  142  and extend between adjacent signal contacts  124 . The connecting strips  224  are bent perpendicular to and extend from the corresponding side strips  222 . The right side rails  202  form right angle shielded spaces that receive corresponding signal contacts  124  to provide electrical shielding along the sides of the signal contacts  124  and between the signal contacts  124 , such as above and/or below corresponding signal contacts  124 . The struts  206  interconnect the right side rails  202  to hold the relative positions of the right side rails  202 . The gaps  204  are defined between the right side rails  202  and generally follow the paths of the right side rails  202 . 
     In an exemplary embodiment, each connecting strip  224  includes a commoning feature  226  for electrically connecting to the second ground shield  182  (shown in  FIG. 2 ). In the illustrated embodiment, the commoning features  226  are commoning tabs that extend outward from the connecting strips  224  and commoning slots; however, other types of commoning features may be used in alternative embodiments, such as channels, spring beams, and the like. The commoning features  226  may be deflectable to engage and securely couple the first ground shield  180  to the second ground shield  182  when mated thereto. For example, the commoning features  226  may be clips. 
     The right side rails  202  are configured to extend along and follow the paths of the signal contacts  124 , such as between the mating end  128  and the mounting end  130  (both shown in  FIG. 1 ) of the electrical connector  102 . For example, the right side rails  202  may transition from the mating end  214  to the mounting end  220  and have different segments or portions  228  that are angled relative to each other as the right side rails  202  transition between the mating and mounting ends  214 ,  220 . 
     In an exemplary embodiment, the first ground shield  180  includes a first ground pad  230  at the mating end  214  forward of the right side rails  202 . The mating beams  210  extend from the first ground pad  230 . The first ground pad  230  is continuous top to bottom and holds the positions of the right side rails  202  and the mating beams  210 . The first ground pad  230  forms continuous shielding along the right sides of the signal contacts  124 . The first ground pad  230  extends between a front  232  and a rear  234 . The mating beams  210  extend forward from the front  232 . The right side rails  202  extend from the rear  234 . Optionally, the first ground pad  230  may be out of plane with the right side rails  202 , such as outward of the side strips  222  and the connecting strips  224 . 
     The first ground pad  230  includes slots  240  having guide features  242 . The slots  240  receive corresponding ground blades  184  (shown in  FIG. 2 ). The guide features  242  engage the ground blades  184  to locate the ground blades  184  relative to the first ground shield  180 . For example, the guide features  242  may vertically positioned in the ground blade  184  in the slot  240 . 
     The first ground shield  180  includes first ground beams  250  extending forward from the front  232  of the first ground pad  230 . In an exemplary embodiment, the first ground beams  250  are integral with the first ground pad  230  and the first mating beams  210  as part of the first ground shield  180 . For example, the first ground shield  180  is an integral, unitary monolithic body forming the first ground pad  230 , the first mating beams  210  and the first ground beams  250 . As such, the first ground beams  250  and the first mating beams  210  are electrically commoned with each other through the first ground pad  230  and are configured to be electrically commoned with each of the header ground shields  114 . The unitary structure controls noise resonance spikes at various frequencies due to electrically connecting the ground beams  250  and the header ground shields  114 . The ground beams  250  are connected near the mating zone to provide resonance control in the mating zone of the connector. 
     The first ground beams  250  are located between corresponding first mating beams  210 . The first ground beams  250  are configured to be mated with corresponding header ground shields  114 . The first ground pad  230  ties each of the first ground beams  250  together to physically hold positions of each of the first ground beams  250  relative to each other and relative to the first mating beams  210 . Each first ground beam  250  includes at least one mating interface  252  configured to engage the corresponding header ground shield(s)  114 . Optionally, the first ground beam  250  may be deflectable when engaging the corresponding header ground shield  114 . For example, the mating interface  252  may be spring biased against the corresponding header ground shield  114 . Optionally, the first ground beam  250  is compressible against the header ground shield(s)  114  when mated thereto. 
       FIG. 4  is an exploded view of the contact module  122  showing the first and second ground shields  180 ,  182  relative to the dielectric bodies  144  of the dielectric holder  142 . The second ground shield  182  may be similar to the first ground shield  180 . In an exemplary embodiment, the second ground shield  182  is stamped and formed from a stock piece of metal material. The second ground shield  182  includes a main body  300  configured to extend along the left side  162  of the dielectric holder  142 . The main body  300  includes a plurality of left side rails  302  separated by gaps  304 . The left side rails  302  are interconnected by struts  306  that span the gaps  304  between the rails  302 . 
     The second ground shield  182  includes mating beams  310  at a mating end  314  of the main body  300 . The mating beams  310  are configured to be mated with corresponding mating portions of the header connector (for example, the C-shaped header ground shields  114 , shown in  FIG. 1 ). In an exemplary embodiment, the mating beams  310  extend along the left sides of the corresponding signal contacts  124 . The mating beams  310  may be deflectable mating beams, such as spring beams. Optionally, the mating beams  310  are configured to be received inside the corresponding C-shaped header ground shields  114  of the header connector  106 . Alternatively, the mating beams  310  are configured to extend along the outside of the corresponding C-shaped header ground shields  114  of the header connector. 
     The second ground shield  182  includes mounting portions  316  defined by compliant pins  318  at a mounting end  320  of the main body  300 . The mounting portions  316  are configured to be terminated to the circuit board  104  (shown in  FIG. 1 ). For example, the mounting portions  316  are configured to be received in plated vias in the circuit board  104 . 
     The left side rails  302  are configured to provide shielding around corresponding signal contacts  124  (shown in  FIG. 2 ). For example, in an exemplary embodiment, the left side rails  302  have side strips  322  configured to extend along the left side  162  of the dielectric holder  142 , and connecting strips  324  configured to extend into the dielectric holder  142  and extend between adjacent signal contacts  124 . The connecting strips  324  are bent perpendicular to and extend from the corresponding side strips  322 . The left side rails  302  form right angle shielded spaces that receive corresponding signal contacts  124  to provide electrical shielding along the sides of the signal contacts  124  and between the signal contacts  124 , such as above and/or below corresponding signal contacts  124 . The struts  306  interconnect the left side rails  302  to hold the relative positions of the left side rails  302 . The gaps  304  are defined between the left side rails  302  and generally follow the paths of the left side rails  302 . 
     In an exemplary embodiment, each connecting strip  324  includes a commoning feature  326  for electrically connecting to the first ground shield  180  (shown in  FIG. 3 ). In the illustrated embodiment, the commoning features  326  are commoning slots in the connecting strips  324  and commoning tabs; however, other types of commoning features may be used in alternative embodiments, such as channels, spring beams, clips, and the like. The commoning features  326  may be deflectable to engage and securely couple the second ground shield  182  to the first ground shield  180  when mated thereto. 
     The left side rails  302  are configured to extend along and follow the paths of the signal contacts  124 , such as between the mating end  128  and the mounting end  130  (both shown in  FIG. 1 ) of the electrical connector  102 . For example, the left side rails  302  may transition from the mating end  314  to the mounting end  320  and have different segments or portions  328  that are angled relative to each other as the left side rails  302  transition between the ends  314 ,  320 . 
     In an exemplary embodiment, each rail  202 ,  302  includes multiple commoning features  226 ,  326  to make periodic, reliable electrical connections therebetween. For example, each portion  228 ,  328  may include at least one commoning feature  226 ,  326 . The commoning features  226 ,  326  may be generally spaced at approximately 3-5 mm apart to achieve good electrical performance in a desired range, such as between 30-40 GHz; however other spacings or other target ranges may be achieved in other embodiments. 
     When assembled, the ground shields  180 ,  182  form C-shaped hoods covering three sides of each pair of signal contacts  124 . For example, the hoods cover both the right and left sides as well as the tops of the signal contacts  124  to shield the pair of signal contacts  124  from other pairs of signal contacts  124 . The rails  202 ,  302  below the pair of signal contacts  124  shield the fourth side of the pair of signal contacts  124  such that the pair is shielded on all four sides. The first and second ground shields  180 ,  182  thus provide circumferential shielding around the pairs of signal contacts  124 . The circumferential shielding is provided around each pair of signal contacts  124  for substantially the entire length of the transition portions  170  (shown in  FIG. 2 ) of the signal contacts. The first and second ground shields  180 ,  182  provide shielding in all line-of-sight directions between all adjacent pairs of signal contacts  124 , including pairs of signal contacts  124  in adjacent contact modules  122 . Optionally, the bottom of the inner-most pair remains unshielded; however, the signal performance of the signal contacts  124  of the inner-most pair remains largely unaffected by having the one side unshielded. Optionally, a shield may be provided at the unshielded side of the inner-most pair. The ground pads  230 , the mating beams  210  and the ground beams  250  of the first ground shield  180  provide shielding along the mating portions  166  of the signal contacts  124 . 
     In an exemplary embodiment, the second ground shield  182  includes a second ground pad  330  forward of the left side rails  302 . The mating beams  310  extend from the second ground pad  330 . The second ground pad  330  is continuous top to bottom and holds the positions of the left side rails  302  with the struts  306 . The second ground pad  330  forms continuous shielding along the left sides of the signal contacts  124 . The second ground pad  330  extends between a front  332  and a rear  334 . The mounting portions  316  extend forward from the front  332 . The left side rails  302  extend from the rear  334 . Optionally, the second ground pad  330  may be out of plane with the left side rails  302 , such as outward of the side strips  322  and the connecting strips  324 . 
     The second ground pad  330  includes slots  340  having guide features  342 . The slots  340  receive corresponding ground blades  184  (shown in  FIG. 2 ). The guide features  342  engage the ground blades  184  to locate the ground blades  184  relative to the first ground shield  182 . For example, the guide features  342  may vertically positioned in the ground blade  184  in the slot  340 . 
     The second ground shield  182  includes second ground beams  350  extending forward from the front  332  of the second ground pad  330 . In an exemplary embodiment, the second ground beams  350  are integral with the second ground pad  330  and the second mating beams  310  as part of the second ground shield  182 . For example, the second ground shield  182  is an integral, unitary monolithic body forming the second ground pad  330 , the second mating beams  310  and the second ground beams  350 . As such, the second ground beams  350  and the second mating beams  310  are electrically commoned with each other through the second ground pad  330  and are configured to be electrically commoned with each of the header ground shields  114 . The unitary structure controls noise resonance spikes at various frequencies due to electrically connecting the ground beams  350  and the header ground shields  114 . The ground beams  350  are connected near the mating zone to provide resonance control in the mating zone of the connector. 
     The second ground beams  350  are located between corresponding second mating beams  310 . The second ground beams  350  are configured to be mated with corresponding header ground shields  114 . The second ground pad  330  ties each of the second ground beams  350  together to physically hold positions of each of the second ground beams  350  relative to each other and relative to the second mating beams  310 . Each second ground beam  350  includes at least one mating interface  352  configured to engage the corresponding header ground shield(s)  114 . Optionally, the second ground beam  350  may be deflectable when engaging the corresponding header ground shield  114 . For example, the mating interface  352  may be spring biased against the corresponding header ground shield  114 . Optionally, the second ground beam  350  is compressible against the header ground shield(s)  114  when mated thereto. 
       FIG. 5  is a perspective view of the contact module  122  in an assembled state showing the first and second ground shields  180 ,  182  coupled to the dielectric holder  142 . The first and second ground shields  180 ,  182  are received in channels in the dielectric holder  142 . The first and second ground pads  230 ,  330  are located along the right and left sides of the dielectric holder  142  at the mating end  150 . Portions of the first and second ground pads  230 ,  330  extend along the right and left sides  160 ,  162 , respectively. The ground beams  250 ,  350  extend forward of the mating end  150  along the mating portions  166  of the signal contacts  124  for mating with the header ground shields  114 . The first and second ground pads  230 ,  330  form continuous shield walls from the top to the bottom of the contact module  122  forward of the mating end  150 . The continuous shield walls provide electrical shielding for the mating portions  166  where the mating portions  166  extend from the mating end  150  of the dielectric holder  142 . The mating beams  210 ,  310  of the first and second ground shields  180 ,  182  extend forward of the first and second ground pads  230 ,  330  along the mating portions  166  of the signal contacts  124  to make electrical connection with the header ground shield  114  (shown in  FIG. 1 ). The mating beams  210 ,  310  and the ground beams  250 ,  350  provide electrical shielding for the mating portions  166  and are configured to be electrically commoned with each of the header ground shields  114 . 
       FIG. 6  is a perspective view of a portion of the electrical connector  102  in accordance with an exemplary embodiment.  FIG. 7  is a side view of a portion of the electrical connector  102  in accordance with an exemplary embodiment.  FIGS. 6-7  illustrate header ground shields  114  mating with the shield structure  126 . When assembled, the ground blade  184  and the ground shields  180 ,  182  provide electrical shielding for the mating portions  166  of the signal contacts  124 . The mating portions  188  of the ground blades  184  are configured to be electrically connected to the corresponding header ground shields  114 , such as to the center walls  117  of the corresponding header ground shields  114 . The mating beams  210 ,  310  ( FIG. 4 ) are configured to be electrically connected to the corresponding header ground shields  114 , such as to the end walls  115 ,  116  of the corresponding header ground shields  114 . The ground beams  250 ,  350  ( FIG. 4 ) are configured to be electrically connected to the corresponding header ground shields  114 , such as to the end walls  115 ,  116  of the corresponding header ground shields  114 . The ground beams  250 ,  350  electrically common the header ground shields  114  to provide resonance control and improve signal integrity of the connector. 
     The main body  185  of the ground blade  184  forms a continuous horizontal wall structure forward of the front  151  of the dielectric holder  142  between the first and second ground pads  230 ,  330  ( FIG. 4 ). The first and second ground pads  230 ,  330  form continuous vertical wall structures forward of the front  151  of the dielectric holder  142 . When another ground blade  184  is positioned below the signal contacts  124 , a rectangular shield pocket is formed providing electrical shielding on all four sides of the pair of signal contacts  124  immediately forward of the mating end  150  of the dielectric holder  142  in the mating zone where the mating portions  166  of the signal contacts  124  transition out of the dielectric holder  142 . The mating portions  188  create points of contact with the header ground shield  114  forward of the ground pads  230 ,  330 . The mating beams  210 ,  310  create points of contact with the header ground shield  114  forward of the ground pads  230 ,  330 . The ground beams  250 ,  350  create points of contact with the header ground shield  114  forward of the ground pads  230 ,  330  to provide electrical shielding around the mating portions  166  of the signal contacts  124 . 
     In an exemplary embodiment, each ground beam  250  includes a main body  260  extending forward from the ground pad  230 . The main body  260  may be deflectable when the ground beam  250  engages the header ground shield  114 . When the main body  260  is flexed, the ground beam  250  is configured to be spring biased against the header ground shield  114 . In an exemplary embodiment, each ground beam  250  includes an upper tab  262  and a lower tab  264 . The upper tab  262  and/or the lower tab  264  are configured to extend from the main body  260 . The upper tab  262  and/or the lower tab  264  may be provided at the distal end of the ground beam  250 . In the illustrated embodiment, the lower tab  264  extends forward from the main body  260  and the upper tab  262  extends from the lower tab  264 . For example, the upper tab  262  may be bent off of the lower tab  264  out of plane with respect to the main body  260 . Other arrangements are possible in alternative embodiments. For example, the upper tab  262  may additionally or alternatively extend from the main body  260 . In various embodiments, the lower tab  264  may extend from the upper tab  262 . 
     Optionally, both the upper tab  262  and the lower tab  264  include a corresponding mating interface  266 ,  268  configured to engage the corresponding header ground shields  114 . The upper mating interface  266  is configured to engage the corresponding header ground shield  114  above the ground beam  250 . For example, the upper tab  262  may interface with the edge  119  of the end wall  115 . The lower mating interface  268  is configured to engage the corresponding header ground shield  114  below the ground beam  250 . For example, the lower tab  264  may interface with the exterior surface of the center wall  117 . The upper and lower tabs  262 ,  264  may interface with other portions of the header ground shields  114 . Optionally, the upper tab  262  and/or the lower tab  264  may be compressed between the adjacent header ground shields  114  when mated thereto. 
       FIG. 8  is a front view of the mating interface of the electrical connector  102  showing the header ground shields  114  relative to the shield structure  126  in accordance with an exemplary embodiment. The first and second ground shields  180 ,  182  are provided along the right and left sides of the pairs of signal contacts  124 . The ground blades  184  are shown above and below the pairs of signal contacts  124 . The main body  185  of the ground blades  184  extends horizontally above the shield pockets surrounding the corresponding pairs of signal contacts  124 . The first and second ground pads  230 ,  330  of the first and second ground shields  180 ,  182  extend vertically along the right and left sides of the shield pockets surrounding the corresponding pairs of signal contacts  124 . The mating portions  188  of the ground blades  184  are aligned vertically above and/or below the corresponding pairs of signal contacts  124 . The mating beams  210 ,  310  of the first and second ground shields  180 ,  182  are horizontally aligned in the row with the corresponding pairs of signal contacts  124 . The ground beams  250 ,  350  are located between the header ground shields  114  and are electrically connected to the header ground shields  114 . 
     The header ground shields  114  are coupled to the shield structure  126 . The mating portions  188  engage the header ground shields  114 . The mating beams  210 ,  310  engage the header ground shields  114 . The ground beams  250 ,  350  engage the header ground shields  114 . The mating portions  188 , the mating beams  210 ,  310  and the ground beams  250 ,  350  are spring biased against corresponding surfaces of the walls of the header ground shields  114 . The location of the mating interfaces of the ground beams  250 ,  350  with the header ground shields  114  may control resonances, such as at target frequencies, such as when connecting proximate to the mating zone of the connector. 
     The mating portions  188  of the ground blade  184  engage the center wall  117 , such as the interior surface  121  of the center wall  117 . The mating beams  210  of the first ground shield  180  engage the first end wall  115 , such as the interior surface  121  of the first end wall  115 . The mating beams  310  of the second ground shield  182  engage the second end wall  116 , such as the interior surface  121  of the second end wall  116 . The ground beams  250  of the first ground shield  180  engage the center wall  117  of the header ground shield  114  below the ground beam  250  and engage the first end wall  115  of the header ground shield  114  above the ground beam  250 . The ground beams  350  of the second ground shield  182  engage the center wall  117  of the header ground shield  114  below the ground beam  350  and engage the second end wall  116  of the header ground shield  114  above the ground beam  350 . 
     The end walls  115 ,  116  and the center wall  117  form continuous shield walls around three sides of the shield pocket for the corresponding pair of signal contacts  124 . The center wall  117  of the header ground shield  114  below the shield pocket forms a continuous wall around the fourth side of the shield pocket. Beyond the tips  118  of the header ground shield  114 , the main body  185  of the ground blade  184  and the first and second ground pads  230 ,  330  of the first and second ground shields  180 ,  182  form continuous walls around all four sides of the pair of signal contacts at the front  151  of the dielectric holder  142 . As such, the shield structure  126  and the header ground shields  114  provide effective electrical shielding for the pairs of signal contacts  124 . The mating portions  166  are thus electrically shielded at the mating zone. The circumferential shielding is provided above, below and along opposite sides of each pair of signal contacts  124  at the mating end  150  of the dielectric holder  142 . The circumferential shielding not only extends along the length of the transition portions  170  of the signal contacts  124 , but is also located immediately forward of the dielectric holder  142 , such as between the header ground shields  114  and the dielectric holder  142 . 
     The stamped and formed first and second ground shields  180 ,  182  and the ground blade  184  are cost effective to manufacture, as compared to conventional plated plastic conductive holders. The stamped and formed first and second ground shields  180 ,  182  and the ground blade  184  provide electrical shielding in all directions for each pair-in-row pair of signal contacts  124 , as compared to conventional ground shields that only extend along the sides of the signal contacts and not above or below the pair of signal contacts. 
       FIG. 9  is a perspective view of a portion of the electrical connector  102  in accordance with an exemplary embodiment.  FIG. 9  illustrates the ground beam  250  having a different shape. In the illustrated embodiment, the upper tab  262  of the ground beam  250  is provided at the distal end of the lower tab  264  and is formed to extend rearward therefrom rather than extending forwardly as in the embodiment shown in  FIGS. 6-8 . 
       FIG. 10  is a side view of a portion of the electrical connector  102  in accordance with an exemplary embodiment.  FIG. 10  illustrates a different type of ground beam  450 . The ground beam  450  includes a main body  460  extending forward from the corresponding ground pad  430  of the ground shield  400 . A ground clip  452  is coupled to the distal end of the main body  460 . The main body  460  is formed integral with the ground pad  430 . The ground clip  452 , in the illustrated embodiment, is a separate piece coupled to the distal end of the main body  460 . For example, the ground clip  452  may be welded to the main body  460 . In alternative embodiments, the ground clip  452  may be formed integral with the main body  460 , such as being stamped and formed with the main body  460 . 
       FIG. 11  is a perspective view of the ground clip  452  in accordance with an exemplary embodiment. The ground clip  452  includes a base  454  configured to be coupled to the main body  460 , such as by welding to the main body  460 . The ground clip  452  includes an upper tab  462  extending from the base  454  and a lower tab  464  extending from the base  454 . Optionally, the upper tab  462  may extend in a different direction than the lower tab  464 , such as to opposite sides of the base  454 . The upper tab  462  includes an upper mating interface  466  and the lower tab  464  includes a lower mating interface  468 . 
       FIG. 12  is a front view of a portion of the electrical connector  102  in accordance with an exemplary embodiment. Each ground clip  452  is configured to be mounted to the main body  460  of the corresponding ground beam  450 . The upper and lower tabs  462 ,  464  extend from the base  454  of the ground clip  452  and are positioned for interfacing with the header ground shields  114  (shown in  FIG. 13 ). 
       FIG. 13  is a front view of the mating interface of the electrical connector  102  showing the header ground shields  114  relative to the shield structure in accordance with an exemplary embodiment. The upper mating interface  466  is configured to engage the corresponding header ground shield  114  above the ground beam  450 . For example, the upper tab  462  may interface with the edge  119  of the end wall  115  or  116  of the header ground shields  114  above the ground beam  450 . The lower mating interface  468  is configured to engage the corresponding header ground shield  114  below the ground beam  450 . For example, the lower tab  464  may interface with the exterior surface of the center wall  117 . The upper and lower tabs  462 ,  464  may interface with other portions of the header ground shields  114 . 
     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.