Patent Publication Number: US-10326244-B2

Title: Electrical connector and electrical contact configured to reduce resonance

Description:
BACKGROUND 
     The subject matter herein relates generally to electrical contacts having stub portions that generate an electrical resonance during operation. 
     Electrical connectors are used to transmit data in various industries. The electrical connectors are often configured to repeatedly engage and disengage complementary electrical connectors. The process of mating the electrical connectors may be referred to as a mating operation. For example, in a backplane communication system, a backplane circuit board has a header connector that is configured to mate with a receptacle connector. The receptacle connector is typically mounted to a daughter card. The header connector includes an array of electrical contacts (hereinafter referred to as “header contacts”), and the receptacle connector includes a complementary array of electrical contacts (hereinafter referred to as “receptacle contacts”). During the mating operation, the receptacle contacts mechanically engage and slide along the corresponding header contacts. The sliding engagement between the receptacle and header contacts may be referred to as a wiping action, because each receptacle contact wipes along a contact surface of the corresponding header contact. 
     During this wiping action, each receptacle contact typically slides from a contact end of the corresponding header contact toward a mating zone along the header contact. The mating zone is a distance away from the contact end of the header contact. The portion of the header contact that extends between the contact end and the mating zone is referred to as a stub portion. During operation of the system, energy propagates from the mating zone to the contact end of the header contact where the energy is then reflected back toward the mating zone. At current transmission speeds the reflected energy may resonate, such that the stub portion acts as an antenna that enables electromagnetic radiation to permeate the interface between the mated header and receptacle contacts. Shielding may be required to contain such electromagnetic interference (EMI) radiated by stub portions acting as antennas, which may be costly and thereby increase the cost of manufacturing the connectors. 
     Accordingly, a need remains for electrical contacts that reduce the unwanted effects of reflected energy along stub portions of the electrical contacts. 
     BRIEF DESCRIPTION 
     In an embodiment, an electrical connector is provided that includes a connector housing configured to engage another connector. The electrical connector also includes a plurality of electrical contacts coupled to the connector housing. Each of the electrical contacts of the plurality of electrical contacts includes a base section coupled to the connector housing and an elongated mating pin coupled to the base section. The mating pin extends away from the base section along a longitudinal axis to a contact end of the mating pin. The mating pin has an exterior surface that forms a runway configured to intimately engage another contact during a mating operation. The runway includes a wipe zone, a resonance-control zone, and a mating zone. The resonance-control zone is located between the mating zone and the wipe zone. The resonance-control zone has a greater elevation than an elevation of the wipe zone and an elevation of the mating zone such that the resonance-control zone deflects the other contact further away during the mating operation. 
     In some aspects, the wipe zone and the mating zone are essentially planar. 
     In some aspects, each of the electrical contacts is stamped-and-formed from sheet material. The resonance-control zone is an embossed region of the sheet material. 
     In some aspects, the mating pin includes two panel sections having a contact gap therebetween. Optionally, the two panel sections are folded about a common fold edge. Optionally, only one of the two panel sections includes the resonance-control zone. The panel sections may be plated. 
     In some aspects, the mating pin includes an elongated opening that extends parallel to the longitudinal axis. The elongated opening defines a bow region of the mating pin that is permitted to flex. For example, the bow region is permitted to bow. The bow region includes the resonance-control zone. 
     In some aspects, the mating pin includes two panel sections having a contact gap therebetween that are folded about a common fold edge. The mating pin also includes an elongated opening that extends parallel to the longitudinal axis along the fold edge and one of the panel sections. The elongated opening defines a bow region of the one panel section that is permitted to flex. The bow region includes the resonance-control zone. 
     In an embodiment, a communication system is provided that includes a mating connector having a mating contact and an electrical connector comprising a connector housing and a plurality of electrical contacts coupled to the connector housing. Each of the electrical contacts of the plurality of electrical contacts includes a base section coupled to the connector housing and an elongated mating pin coupled to the base section. The mating pin extends away from the base section along a longitudinal axis to a contact end of the mating pin. The mating pin has an exterior surface that forms a runway configured to intimately engage another contact during a mating operation. The runway includes a wipe zone, a resonance-control zone, and a mating zone. The resonance-control zone is located between the mating zone and the wipe zone. The resonance-control zone has a greater elevation than an elevation of the wipe zone and an elevation of the mating zone such that the resonance-control zone deflects the other contact further away during the mating operation. 
     In some aspects, the mating contact has a contoured end segment and the connector housing has an interior surface. The contoured end segment and the interior surface are shaped relative to one another such that the contoured end segment is blocked by the interior surface of the connector housing prior to or during the mating operation. 
     In some aspects, the mating contact is configured to slidably engage the runway and move in an essentially linear direction along the runway during the mating operation. The wipe zone and the mating zone are essentially planar. 
     In some aspects, each of the electrical contacts is stamped-and-formed from sheet material. The resonance-control zone is an embossed region of the sheet material. 
     In some aspects, the mating pin includes two panel sections having a contact gap therebetween. The two panel sections are folded about a common fold edge, wherein only one of the two panel sections includes the resonance-control zone. 
     In some aspects, the mating pin includes an elongated opening that extends parallel to the longitudinal axis. The elongated opening defines a bow region of the mating pin that is permitted to flex. The bow region includes the resonance-control zone. 
     In some aspects, the mating contact includes first and second contact fingers that oppose each other with a contact-receiving space therebetween. The electrical contact is disposed between the contact-receiving space. 
     Optionally, the first contact finger has a contoured end segment and the connector housing has an interior surface. The contoured end segment of the first contact finger and the interior surface are shaped relative to one another such that the contoured end segment of the first contact finger is blocked by the interior surface of the connector housing. The second contact finger has a contoured end segment. The contoured end segment of the second contact finger and the interior surface are shaped relative to one another such that a flex gap exists between the contoured end segment of the second contact finger and the interior surface of the connector housing. The second contact finger is permitted to move during the mating operation 
     In an embodiment, an electrical contact is provided that includes a base section and an elongated mating pin coupled to the base section. The mating pin extends away from the base section along a longitudinal axis to a contact end of the mating pin. The mating pin has an exterior surface that forms a runway configured to intimately engage another contact during a mating operation. The runway includes a wipe zone, a resonance-control zone, and a mating zone. The resonance-control zone is located between the mating zone and the wipe zone, wherein the resonance-control zone has a greater elevation than an elevation of the wipe zone and an elevation of the mating zone such that the resonance-control zone deflects the other contact further away during the mating operation. 
     In some aspects, the mating pin includes two panel sections folded about a common fold edge and having a contact gap therebetween. The mating pin also includes an elongated opening that extends parallel to the longitudinal axis along the fold edge and one of the panel sections. The elongated opening defines a bow region of the one panel section. The bow region is permitted to flex and includes the resonance-control zone. 
     In some aspects, the mating pin includes two panel sections having a contact gap therebetween. The two panel sections are folded about a common fold edge, wherein only one of the two panel sections includes the resonance-control zone. 
     In some aspects, the mating pin includes an elongated opening that extends parallel to the longitudinal axis. The elongated opening defines a bow region of the mating pin that is permitted to flex. The bow region includes the resonance-control zone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a communication system formed in accordance with an embodiment. 
         FIG. 2  is a perspective view of a circuit board assembly including a header connector that may be used with the communication system of  FIG. 1 . 
         FIG. 3  is a perspective view of a receptacle connector that may be used with the communication system of  FIG. 1 . 
         FIG. 4  is an isolated perspective view of an electrical contact formed in accordance of an embodiment. 
         FIG. 5  is an enlarged view of a mating pin of the electrical contact of  FIG. 4 . 
         FIG. 6  is another enlarged view of the mating pin of the electrical contact of  FIG. 4 . 
         FIG. 7  is a cross-section of a connector assembly as the electrical contact of  FIG. 4  engages another contact. 
         FIG. 8  is an enlarged view of a mating pin of an electrical contact formed in accordance with an embodiment. 
         FIG. 9  is another enlarged view of the mating pin of the electrical contact of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments set forth herein may include electrical contacts, electrical connectors having the electrical contacts, connector assemblies including the electrical connectors, and communication systems having the electrical connectors, among other things. Embodiments may be configured to improve electrical performance by, for example, damping or impeding electrical resonance that may occur in stub portions of electrical contacts. More specifically, electrical contacts may include a protrusion that forms a resonance-control zone where the electrical contact engages another contact. 
     The electrical contacts may form signal paths in which data signals are transmitted through the electrical contacts. Alternatively, the electrical contacts may form ground conductors in which each ground conductor shields adjacent signal paths from one another and provides a return path. Each electrical contact is configured to be engaged by another contact at a contact zone. The contact zone is located a distance away from an end of the electrical contact thereby forming the stub portion. More specifically, the stub portion is the portion of the electrical contact in which energy resonates between the end of the electrical contact and the contact zone. 
     In some embodiments, the electrical connectors are configured to mate with other electrical connectors during a mating operation. During the mating operation, a first electrical contact of one connector may engage and slide (or wipe) along a second electrical contact of the other connector. The second electrical contact may include, among other things, a wipe runway. The first electrical contact slides along the wipe runway of the second electrical contact and operably engages the second electrical contact at the contact zone. 
     Although the illustrated embodiment includes electrical connectors that are used in high-speed communication systems, such as, but not limited to, backplane or midplane communication systems, it should be understood that embodiments may be used in other communication systems and/or in other systems/devices that utilize electrical contacts having stub portions. It should also be understood that embodiments do not require a wiping action between two electrical contacts. Accordingly, the inventive subject matter is not limited to the illustrated embodiment. 
     In particular embodiments, the electrical contacts provide signal pathways for transmitting data signals. Embodiments may be particularly suitable for communication systems, such as, but not limited to, network systems, servers, data centers, and/or the like, in which the data rates may be greater than ten (10) gigabits/second (Gbps) or greater than five (5) gigahertz (GHz). One or more embodiments may be configured to transmit data at a rate of at least 20 Gbps, at least 40 Gbps, at least 56 Gbps, or more. One or more embodiments may be configured to transmit data at a frequency of at least 10 GHz, at least 20 GHz, at least 28 GHz, or more. As used herein with respect to data transfer, the term “configured to” does not mean mere capability in a hypothetical or theoretical sense, but means that the embodiment is designed to transmit data at the designated rate or frequency for an extended period of time (e.g., expected time periods for commercial use) and at a signal quality that is sufficient for its intended commercial use. It is contemplated, however, that other embodiments may be configured to operate at data rates that are less than 10 Gbps or operate at frequencies that are less than 5 GHz. 
     Various embodiments may be configured for certain applications. One or more embodiments may be configured for backplane or midplane communication systems. For example, one or more of the electrical connectors described herein may be similar to electrical connectors of the STRADA Whisper or Z-PACK TinMan product lines developed by TE Connectivity. The electrical connectors may include high-density arrays of electrical contacts. A high-density array may have, for example, at least 12 signal contacts per 100 mm 2  along the mating side or the mounting side of the electrical connector. In more particular embodiments, the high-density array may have at least 20 signal contacts per 100 mm 2 . 
     Non-limiting examples of some applications that may use embodiments set forth herein include host bus adapters (HBAs), redundant arrays of inexpensive disks (RAIDs), workstations, servers, storage racks, high performance computers, or switches. Embodiments may also include electrical connectors that are small-form factor connectors. For example, the electrical connectors may be configured to be compliant with certain standards, such as, but not limited to, the small-form factor pluggable (SFP) standard, enhanced SFP (SFP+) standard, quad SFP (QSFP) standard, C form-factor pluggable (CFP) standard, and 10 Gigabit SFP standard, which is often referred to as the XFP standard. 
     Electrical contacts described herein may include a plurality of different materials. For example, an electrical contact may include a base material, such as, but not limited to, copper or copper alloy (e.g., beryllium copper), that is plated or coated with one or more other materials. As used herein, when another material is “plated over” or “coated over” a base material, the other material may directly contact or bond to an outer surface of the base material or may directly contact or bond to an outer surface of an intervening material. More specifically, the other material is not required to be directly adjacent to the base material and may be separated by an intervening layer. 
     Different materials of an electrical contact may be selected to impede electrical resonance along any stub portions. For example, one or more of the materials used in the electrical contacts may be ferromagnetic. More specifically, one or more materials may have a higher relative magnetic permeability. In particular embodiments, the electrical contact includes a material that has a permeability that is, for example, greater than 50. In some embodiments, the permeability is greater than 75 or, more specifically, greater than 100. In certain embodiments, the permeability is greater than 150 or, more specifically, greater than 200. In particular embodiments, the permeability is greater than 250, greater than 350, greater than 450, greater than 550, or more. Non-limiting examples of such materials include nickel, carbon steel, ferrite (nickel zinc or manganese zinc), cobalt, martensitic stainless steel, ferritic stainless steel, iron, alloys of the same, and/or the like. In some embodiments, the material is a martensitic stainless steel (annealed). Materials that have a higher permeability provide a higher internal self-inductance. High permeability may also cause shallow skin depths, which may increase the effective resistance of the electrical contact within a predetermined frequency band. 
     As used herein, phrases such as “a plurality of [elements]” and “an array of [elements]” and/or the like, when used in the detailed description and claims, do not necessarily include each and every element that a component may have. The component may have other elements that are similar to the plurality of elements. For example, the phrase “a plurality of electrical contacts [being/having a recited feature]” does not necessarily mean that each and every electrical contact of the component has the recited feature. Other electrical contacts may not include the recited feature. Accordingly, unless explicitly stated otherwise (e.g., “each and every electrical contact of the electrical connector [being/having a recited feature]”), embodiments may include similar elements that do not have the recited features. 
     In order to distinguish similar elements in the detailed description and claims, various labels may be used. For example, an electrical connector may be referred to as a header connector, a receptacle connector, and/or a mating connector. Electrical contacts may be referred to as header contacts, receptacle contacts, and/or mating contacts. When similar elements are labeled differently (e.g., receptacle contacts and mating contacts), the different labels do not necessarily require structural differences. 
     Embodiments set forth herein are described with respect a backplane or midplane communication system having a central printed circuit board (PCB). Header connectors are mounted to each side of the PCB. The header connectors include electrical contacts, such as the electrical contacts described herein. Conductive pathways extend through the PCB via plated thru-holes (PTHs) and conductive traces. The conductive pathways electrical connect different electrical contacts of the header connectors. Receptacle daughtercards are mated to the header connectors on both sides of the PCB. 
     Yet alternative configurations of such communication systems exist. In one configuration, the header connectors are mounted to only one side of the PCB and receptacle daughtercards are mated to the same side. In another configuration (referred to as a direct plug orthogonal (DPO) configuration), a central PCB does not exist. Mezzanine (parallel) PCB configurations are also contemplated. Accordingly, it should be understood that the electrical contacts set forth herein may be used in a number of different applications. 
       FIG. 1  is a perspective view of a communication system  100  formed in accordance with an embodiment. The communication system  100  is an electrical connector system. The communication system  100  includes a circuit board assembly  102 , a first connector system (or assembly)  104  configured to be coupled to one side of the circuit board assembly  102 , and a second connector system (or assembly)  106  configured to be coupled to an opposite side the circuit board assembly  102 . The circuit board assembly  102  is used to electrically connect the first and second connector systems  104 ,  106 . Optionally, either of the first and second connector systems  104 ,  106  may be part of a line card assembly or a switch card assembly. Although the communication system  100  is configured to interconnect two connector systems in the illustrated embodiment, other communication systems may interconnect more than two connector systems or, alternatively, interconnect a single connector system to another communication device. 
     The circuit board assembly  102  includes a circuit board  110  having a first board side  112  and second board side  114 . In some embodiments, the circuit board  110  may be a backplane circuit board, a midplane circuit board, or a motherboard. The circuit board assembly  102  includes a first header connector  116  mounted to and extending from the first board side  112  of the circuit board  110 . The circuit board assembly  102  also includes a second header connector  118  mounted to and extending from the second board side  114  of the circuit board  110 . The first and second header connectors  116 ,  118  include connector housings  117 ,  119 , respectively. The first and second header connectors  116 ,  118  also include corresponding electrical contacts  120  that are electrically connected to one another through the circuit board  110 . The electrical contacts  120  are hereinafter referred to as header contacts  120 . The electrical contacts  120  may be similar to the electrical contacts  300  ( FIG. 4 ). 
     The circuit board assembly  102  includes a plurality of signal paths therethrough defined by the header contacts  120  and conductive vias  170  (shown in  FIG. 2 ) that extend through the circuit board  110 . The header contacts  120  of the first and second header connectors  116 ,  118  may be received in the same conductive vias  170  to define a signal path directly through the circuit board  110 . In an exemplary embodiment, the signal paths pass straight through the circuit board assembly  102  in a linear manner. Alternatively, the header contacts  120  of the first header connector  116  and the header contacts  120  of the second header connector  118  may be inserted into different conductive vias  170  that are electrically coupled to one another through traces (not shown) of the circuit board  110 . 
     In other embodiments, the system may have a DPO configuration in which a mid-plane or backplane circuit board does not exist. In such embodiments, a single connector may be used to interconnect two receptacle connectors more directly. The electrical contact  300  (shown in  FIG. 4 ) may be used in such embodiments. 
     The first and second header connectors  116 ,  118  include ground shields or contacts  122  that provide electrical shielding around corresponding header contacts  120 . In an exemplary embodiment, the header contacts  120  are arranged in signal pairs  121  and are configured to convey differential signals. Each of the ground shields  122  may peripherally surround a corresponding signal pair  121 . As shown, the ground shields  122  are C-shaped or U-shaped and cover the corresponding signal pair  121  along three sides. 
     The connector housings  117 ,  119  couple to and hold the header contacts  120  and the ground shields  122  in designated positions relative to each other. The connector housings  117 ,  119  may be manufactured from a dielectric material, such as, but not limited to, a plastic material. Each of the connector housings  117 ,  119  includes a mounting wall  126  that is configured to be mounted to the circuit board  110 , and shroud walls  128  that extend from the mounting wall  126 . The shroud walls  128  cover portions of the header contacts  120  and the ground shields  122 . 
     The first connector system  104  includes a first circuit board  130  and a first receptacle connector  132  that is mounted to the first circuit board  130 . The first receptacle connector  132  is configured to be coupled to the first header connector  116  of the circuit board assembly  102  during a mating operation. The first receptacle connector  132  has a mating interface  134  that is configured to be mated with the first header connector  116 . The first receptacle connector  132  has a board interface  136  configured to be mated with the first circuit board  130 . In an exemplary embodiment, the board interface  136  is oriented perpendicular to the mating interface  134 . When the first receptacle connector  132  is coupled to the first header connector  116 , the first circuit board  130  is oriented perpendicular to the circuit board  110 . 
     The first receptacle connector  132  includes a connector housing  138 . The connector housing  138  may be referred to as a front housing or shroud in some embodiments. The connector housing  138  is configured to hold a plurality of contact modules  140  side-by-side. As shown, the contact modules  140  are held in a stacked configuration generally parallel to one another. In some embodiments, the contact modules  140  hold a plurality of electrical contacts  142  ( FIG. 3 ) that are electrically connected to the first circuit board  130 . The electrical contacts  142  are hereinafter referred to as receptacle contacts  142 . The receptacle contacts  142  are configured to be electrically connected to the header contacts  120  of the first header connector  116 . 
     The second connector system  106  includes a second circuit board  150  and a second receptacle connector  152  coupled to the second circuit board  150 . The second receptacle connector  152  is configured to be coupled to the second header connector  118  during a mating operation. The second receptacle connector  152  has a mating interface  154  configured to be mated with the second header connector  118 . The second receptacle connector  152  has a board interface  156  configured to be mated with the second circuit board  150 . In an exemplary embodiment, the board interface  156  is oriented perpendicular to the mating interface  154 . When the second receptacle connector  152  is coupled to the second header connector  118 , the second circuit board  150  is oriented perpendicular to the circuit board  110 . 
     Similar to the first receptacle connector  132 , the second receptacle connector  152  includes a connector housing  158  used to hold a plurality of contact modules  160 . The connector housing  158  may be referred to as a front housing or shroud in some embodiments. The contact modules  160  are held in a stacked configuration generally parallel to one another. The contact modules  160  hold a plurality of receptacle contacts (not shown) that are electrically connected to the second circuit board  150 . The receptacle contacts are configured to be electrically connected to the header contacts  120  of the second header connector  118 . The receptacle contacts of the contact modules  160  may be similar or identical to the receptacle contacts  142  ( FIG. 3 ). 
     In the illustrated embodiment, the first circuit board  130  is oriented generally horizontally. The contact modules  140  of the first receptacle connector  132  are oriented generally vertically. The second circuit board  150  is oriented generally vertically. The contact modules  160  of the second receptacle connector  152  are oriented generally horizontally. As such, the first connector system  104  and the second connector system  106  may have an orthogonal orientation with respect to one another. 
     Although not shown, in some embodiments, the communication system  100  may include a loading mechanism. The loading mechanism may include, for example, latches or levers that fully mate the corresponding receptacle and header connectors. For instance, the loading mechanism may be operably coupled to the receptacle connector  132  and, when actuated, drive the receptacle connector  132  into the header connector  116  to assure that the receptacle and header connectors  132 ,  116  are fully mated. 
       FIG. 2  is a partially exploded view of the circuit board assembly  102  showing the first and second header connectors  116 ,  118  positioned for mounting to the circuit board  110 . Although the following description is with respect to the second header connector  118 , the description is also applicable to the first header connector  116 . As shown, the connector housing  119  includes a contact end  162  that faces away from the second board side  114  of the circuit board  110 . The connector housing  119  defines a housing cavity  164  that opens to the contact end  162  and is configured to receive the second receptacle connector  152  ( FIG. 1 ) when the second receptacle connector  152  is advanced into the housing cavity  164 . As shown, the second header connector  118  includes a contact array  168  that includes the header contacts  120  and the ground shields  122 . The contact array  168  may include multiple signal pairs  121 . 
     The conductive vias  170  extend into the circuit board  110 . In an exemplary embodiment, the conductive vias  170  extend entirely through the circuit board  110  between the first and second board sides  112 ,  114 . In other embodiments, the conductive vias  170  extend only partially through the circuit board  110 . The conductive vias  170  are configured to receive the header contacts  120  of the first and second header connectors  116 ,  118 . For example, the header contacts  120  include mating pins  172  that are configured to be loaded into corresponding conductive vias  170 . The mating pins  172  mechanically engage and electrically couple to the conductive vias  170 . Likewise, at least some of the conductive vias  170  are configured to receive mating pins  174  of the ground shields  122 . The mating pins  174  mechanically engage and electrically couple to the conductive vias  170 . The conductive vias  170  that receive the ground shields  122  may surround the pair of conductive vias  170  that receive the corresponding pair of header contacts  120 . 
     The ground shields  122  are C-shaped and provide shielding on three sides of the signal pair  121 . The ground shields  122  have a plurality of walls, specifically three planar walls  176 ,  178 ,  180 . The planar walls  176 ,  178 ,  180  may be integrally formed or alternatively, may be separate pieces. The mating pins  174  extend from each of the planar walls  176 ,  178 ,  180  to electrically connect the planar walls  176 ,  178 ,  180  to the circuit board  110 . The planar wall  178  defines a center wall or top wall of the ground shield  122 . The planar walls  176 ,  180  define side walls that extend from the planar wall  178 . The planar walls  176 ,  180  may be generally perpendicular to the planar wall  178 . In alternative embodiments, other configurations or shapes for the ground shields  122  are possible in alternative embodiments. For example, more or fewer walls may be provided in alternative embodiments. The walls may be bent or angled rather than being planar. In other embodiments, the ground shields  122  may provide shielding for individual header contacts  120  or sets of contacts having more than two header contacts  120 . 
     The header contact  120  includes a contact end  182  and a back end  184 . A conductive pathway exists between the contact and back ends  182 ,  184 . The back end  184  is configured to engage the circuit board  110 . The contact end  182  may represent the portion of the header contact  120  that is located furthest from the circuit board  110  or the mounting wall  126  and is the first to engage or interface with the second receptacle connector  152  ( FIG. 1 ). As such, the contact end  182  may also be referred to as the leading end or the mating end. 
     The header contact  120  also includes a contact body  181 . The header contact  120  (or the contact body  181 ) includes a plurality of segments that are shaped differently from one another and may have different functions. For example, the header contact  120  includes the mating pin  172 , a base section  186 , and a mating segment  188 . The mating pin  172  includes the back end  184 , and the mating segment  188  includes the contact end  182 . As described above, the mating pin  172  mechanically engages and electrically couples to a corresponding conductive via  170  of the circuit board  110 . 
     The base section  186  is sized and shaped to directly engage the mounting wall  126  of the connector housing  119 . For example, the base section  186  may be inserted into a passage (not shown) of the mounting wall  126  and engage the mounting wall  126  to form an interference fit therewith. 
     The mating segment  188  may represent the portion of the header contact  120  that is exposed within the housing cavity  164 . As described below, the mating segment  188  (or a portion thereof) is configured to slidably engage a corresponding receptacle contact  142  ( FIG. 3 ) during the mating operation. 
       FIG. 3  is a partially exploded view of the first connector system  104  including the first receptacle connector  132 . Although the following description is with respect to the first receptacle connector  132 , the description is also applicable to the second receptacle connector  152  ( FIG. 1 ).  FIG. 3  illustrates one of the contact modules  140  in an exploded state. The connector housing  138  includes a plurality of contact openings  200 ,  202  at a contact end  204  of the connector housing  138 . The contact end  204  defines the mating interface  134  of the first receptacle connector  132  that engages the first header connector  116  ( FIG. 1 ). 
     The contact modules  140  are coupled to the connector housing  138  such that the receptacle contacts  142  are received in corresponding contact openings  200 . Optionally, a single receptacle contact  142  may be received in each contact opening  200 . The contact openings  200  receive corresponding header contacts  120  ( FIG. 1 ) therein when the receptacle and header connectors  132 ,  116  are mated. The contact openings  202  receive corresponding ground shields  122  ( FIG. 1 ) therein when the receptacle and header connectors  132 ,  116  are mated. 
     The connector housing  138  may be manufactured from a dielectric material, such as, but not limited to, a plastic material, and may provide isolation between the contact openings  200  and the contact openings  202 . The connector housing  138  may isolate the receptacle contacts  142  and the header contacts  120  from the ground shields  122 . In some embodiments, the contact module  140  includes a conductive holder  210 . The conductive holder  210  may include a first holder member  212  and a second holder member  214  that are coupled together. The holder members  212 ,  214  may be fabricated from a conductive material. As such, the holder members  212 ,  214  may provide electrical shielding for the first receptacle connector  132 . When the holder members  212 ,  214  are coupled together, the holder members  212 ,  214  define at least a portion of a shielding structure. 
     The conductive holder  210  is configured to support a frame assembly  220  that includes a pair of dielectric frames  230 ,  232 . The dielectric frames  230 ,  232  are configured to surround signal conductors (not shown) that are electrically coupled to or include the receptacle contacts  142 . Each signal conductor may also be electrically coupled to or may include a mounting contact  238 . The mounting contacts  238  are configured to mechanically engage and electrically couple to conductive vias  262  of the first circuit board  130 . Each of the receptacle contacts  142  may be electrically coupled to a corresponding mounting contact  238  through a corresponding signal conductor (not shown). 
       FIG. 4  is an isolated perspective view of an electrical contact  300 . The electrical contact  300  includes features that are similar to the header contact  120  ( FIG. 1 ). An electrical connector, such as the electrical connector  116 , may include a plurality of the electrical contacts  300  coupled to the connector housing. The electrical contact  300  may be configured to directly engage two contacts from different connectors (e.g., receptacle connectors). Unlike the header contact  120 , the electrical contact  300  does not directly engage a circuit board. However, alternative embodiments of the electrical contact  300  may be configured to replace the header contact  120  in the communication system  100 . The electrical contact  300  may be stamped-and-formed from sheet material, although other processes may be contemplated. 
     The electrical contact  300  includes first and second contact ends  302 ,  304 . A conductive pathway exists between the first and second contact ends  302 ,  304 . The first contact end  302  is configured to engage another contact, such as the electrical contact  402  ( FIG. 7 ) (hereinafter referred to as “another contact” or “the other contact”). In the illustrated embodiment, the second contact end  304  is also configured to engage another contact (not shown), which may be similar or identical to the other contact  402 . Alternatively, the second contact end  304  may be configured to engage a circuit board. The first contact end  302  may represent the portion of the electrical contact  300  that is located furthest from the connector housing and is first to engage the other contact  402 . As such, the first contact end  302  may also be referred to as the leading end or the mating end. 
     The electrical contact  300  has a contact body  306 . The electrical contact  300  (or the contact body  306 ) includes a plurality of sections that are shaped differently from one another and may have different functions. For example, the electrical contact  300  (or the contact body  306 ) includes a first elongated mating pin  310 , a base section  312 , and a second elongated mating pin  314 . The first mating pin  310  includes the first contact end  302 , and the second mating pin  314  includes the second contact end  304 . 
     The base section  312  extends between and mechanically and electrically couples the first and second mating pins  310 ,  314 . The first and second mating pins  310 ,  312  extend in opposite directions from the base section  312 . The base section  312  is sized and shaped to mechanically couple to a connector housing. For example, the base section  312  may form an interference fit with the mounting wall  126  ( FIG. 1 ) of the connector housing  119  ( FIG. 1 ). In the illustrated embodiment, the base section  312  has a planar body  316  defined between opposite edges  318 ,  320 . The body  316  and the edges  318 ,  320  are shaped to engage the connector housing. 
     Each of the first and second mating pins  310 ,  314  extends away from the base section  312  along a longitudinal axis  324  to the respective contact end of the mating pin. The first mating pin  310  has a width  331 . As described herein, the width  331  may change along mating pin  310  due to a protrusion. The second mating pin  314  has an essentially uniform width  331  and does not include a protrusion. 
     Each of the longitudinal axes  324  extends through a geometric center of a cross-sectional profile of the respective mating pin. In the illustrated embodiment, the longitudinal axes  324  appear to be straight lines. In other embodiments, however, the longitudinal axes  324  may bend as the shape of the respective mating pin changes along a length of the electrical contact  300 . The different longitudinal axes  324  may coincide with one another or, in other words, be the same axis. Yet in other embodiments, the mating pins  310 ,  314  are shaped differently such that the longitudinal axes  324  do not coincide. 
     Each of the first and second mating pins  310 ,  314  has an exterior surface  330 . In the illustrated embodiment, the exterior surfaces  330  are nearly identical, except for a resonance-control zone (described below). In alternative embodiments, the first and second mating pins  310 ,  314  may be identical. The exterior surface  330  includes opposite first and second runways  332 ,  334 . The first runway  332  is configured to engage a first contact finger  402  (shown in  FIG. 7 ) of the other contact  402  ( FIG. 7 ), and the second runway  334  is configured to engage a second contact finger  404  (shown in  FIG. 7 ) of the other contact. The other contact  402  may be a receptacle contact in which the first and second contact fingers  402 ,  404  oppose each other and are configured to receive the electrical contact  300  therebetween. The first and second contact fingers  402 ,  404  are configured to deflect and slidably engage the first and second runways  332 ,  334  of the exterior surface  330 . 
     As shown in  FIG. 4 , a plane  340  intersects the first mating pin  310 . The first runway  332  and the second runway  334  face away from the plane  340  in opposite directions. The electrical contact  300  and the other contact  402  ( FIG. 7 ) are configured to engage each other during a mating operation in which the electrical contact  300  and the other contact  402  move relatively toward one another along the longitudinal axis  324 . In the illustrated embodiment, the other contact  402  is moved toward the electrical contact  300 , but it is also contemplated that the electrical contact  300  may move toward the other contact or that both contacts may move toward each other at the same time. 
     The first runway  332  includes a wipe zone  350 , a resonance-control zone  352 , and a mating zone  354 . The resonance-control zone  352  is located between the mating zone  354  and the wipe zone  350 . The wipe zone  350  extends between the resonance-control zone  352  and the first contact end  302 . The mating zone  354  extends between the resonance-control zone  352  and the base section  306 . 
     As shown, the resonance-control zone  352  has an elevation (or dimension)  353  relative to the plane  340  that is different than a corresponding elevation  351  of the wipe zone  350  and a corresponding elevation  355  of the mating zone  354 . In the illustrated embodiment, the elevations  351 ,  355  of the wipe zone  350  and the mating zone  354 , respectively, are essentially the same. The elevation  353  of the resonance-control zone  352  is greater than each of the elevations  351 ,  355 . The difference between the elevation  353  and one or both of the elevations  351 ,  355  may be, for example, between 0.04 and 0.15 millimeters (mm). With respect to the resonance-control zone  352  and the mating zone  354 , the difference may be measured from a top of the resonance-control zone  352  to where the other contact engages the mating zone  354 , such as the localized area  470  (shown in  FIG. 7 ) of the mating zone  354 . 
     In some embodiments, the difference between the elevation  353  and one or both of the elevations  351 ,  355  may be between 0.05 and 0.12 mm. In more particular embodiments, the difference between the elevation  353  and one or both of the elevations  351 ,  355  may be between 0.06 and 0.10 mm. As one particular example, the difference between the elevation  353  and the elevations  351 ,  355  is about 0.08 mm. However, the difference in elevation may be less or greater than the examples above in other embodiments. In the illustrated embodiment, the wipe zone  350  and the mating zone  354  are essentially planar, but it is contemplated that one or more shaped features may be permitted. In particular embodiments, the wipe zone  350  and the mating zone  354  are essentially planar and the resonance-control zone  352  (or protrusion)  370  is the only shaped feature. 
     As shown in  FIG. 4 , the second runway  334  is essentially planar and does not include changes in elevation. In alternative embodiments, however, the second runway  334  may be shaped similar or identical to the first runway  332 . 
       FIGS. 5 and 6  are enlarged views of the first mating pin  310 . In some embodiments, the electrical contact  300  is stamped-and-formed from sheet material, such as sheet metal  358 . Before or after shaping the sheet metal  358 , the sheet metal  358  may be coated with a material to form a contact plating  359 . The contact plating  359  may comprise, for instance, a gold alloy. One or more additional layers (not shown) may exist that define the sheet metal  358  and/or the contact plating  359 . 
     The contact body  306  may include first and second panel sections  362 ,  364  that are coupled to one another and folded about a common fold edge  366  ( FIG. 5 ). A contact gap  368  exists between the first and second panel sections  362 ,  364 . The first panel section  362  includes the first runway  332  and has a first panel edge  363 , and the second panel section  364  includes the second runway  334  and has a second panel edge  365 . As shown in  FIGS. 5 and 6 , the first panel section  362  includes a protrusion  370 . The protrusion  370  is a localized region of the first panel section  362  that is a topological deviation (e.g., abrupt change in elevation) from the surrounding surface. For example, the protrusion  370  may be an embossed or dimpled region of the sheet material. In the illustrated embodiment, the protrusion  370  does not cover an entire height or width of the first panel section  362  or of the first mating pin  310 . The first panel edge  363  includes the protrusion  370 . The second panel section  362  does not include a similar protrusion in the illustrated embodiment, but it is contemplated that alternative embodiments may include a protrusion. 
     The first panel section  362  is bent or otherwise shaped to form the protrusion  370 , thereby providing different elevations along the first runway  332 . The resonance-control zone  352  of the first runway  332  corresponds to the protrusion  370 . More specifically, the resonance-control zone  352  corresponds to the exterior surface  330  along the protrusion  370 . The portions of the first panel section  362  corresponding to the wipe zone  350  and the mating zone  354  are not bent or otherwise shaped. 
     Also shown in  FIGS. 5 and 6 , the first contact end  302  is defined by the first and second panel sections  362 ,  364 . The first and second panel sections  362 ,  364  at the first contact end  302  may be bent toward one another to provide a tapering or chamfered contact end, which may reduce the likelihood of the other contact being damaged during the mating operation. 
       FIG. 7  is a cross-section of a portion of a communication system  400  after the electrical contact  300  and the other contact  402  are fully mated.  FIG. 7  includes a side view of a portion of the other contact  402 . The other contact  402  is part of a mating connector, such as the receptacle connector  132  ( FIG. 1 ). The other contact  402  includes a base portion  404  and a mating portion  406  that is coupled to the base portion  404 . Although not shown, the other contact  402  may include a terminal portion that is coupled to a conductor of the mating connector. 
     The mating portion  406  is configured to engage the electrical contact  300  to establish an electrical connection between the electrical contact  300  and the other contact  402 . The mating portion  406  includes at least one contact finger. For example, the mating portion  406  includes a first contact finger  408  and a second contact finger  410 . The first and second contact fingers  408 ,  410  are coupled to the base portion  404 . The first and second contact fingers  408 ,  410  have respective joints  412 ,  413  that directly connects to the base portion  404 . The first and second contact fingers  408 ,  410  have respective distal tips  414 ,  415 . The first and second contact fingers  408 ,  410  extend lengthwise between the respective joints  412 ,  413  and the respective distal tips  414 ,  415 . 
     In the illustrated embodiment, the first and second contact fingers  408 ,  410  are spring contacts that are configured to be resiliently deflected when engaged with the electrical contact  300 . The first and second contact fingers  408 ,  410  have respective engagement surfaces  409 ,  411 . A contact-receiving space  416  exists between the engagement surfaces  409 ,  411  and represents a space that will receive the electrical contact  300 . The engagement surface  409  is shaped to define a primary contact zone  418  of the first contact finger  408 , and the engagement surface  411  is shaped to define a primary contact zone  420  of the second contact finger  410 . The first contact finger  408  may also be shaped (relative to the electrical contact  300 ) to define a stub-contact zone  424  in which the first contact finger  408  engages the resonance-control zone  352  (or protrusion  370 ) of the electrical contact  300 . 
     As shown in  FIG. 7 , the first contact finger  408  has a contoured end segment  432  that extends between the primary contact zone  418  and the distal tip  414 . The second contact finger  410  has a contoured end segment  434  that extends between the contact zone  420  of the second contact finger  410  and the distal tip  415 . In  FIG. 7 , the contoured end segment  432  of the first contact finger  408  is longer than the contoured end segment  434  of the second contact finger  410 . The contoured end segment  432  may be sized and shaped relative to a connector housing  440  of the mating connector such that the contoured end segment  432  engages the connector housing  440  prior to or during the mating operation. The connector housing  440  may block movement of the contoured end segment  432  while permitting the first contact finger  408  to bow when the stub-contact zone  424  engages the electrical contact  300 . 
     During a mating operation, as the electrical contact  300  is inserted into the contact-receiving space  416  of the other contact  402 , the primary contact zones  418 ,  420  engage the first and second runways  332 ,  334 , respectively, thereby deflecting the first and second contact fingers  408 ,  410 , respectively. The other contact  402  is configured to slidably engage the runway  332  and relatively move in an essentially linear direction, except for the deflection, along the runway  332  during the mating operation. The primary contact zone  418  slides along the wipe zone  350 , the resonance-control zone  352 , and the mating zone  354 . In the fully mated position (as shown in  FIG. 7 ) the primary contact zone  418  presses against a localized area  470  of the mating zone  354 . In the illustrated embodiment, the mating zone  354  does not include any additional increases in elevation from the protrusion  370  to at least the localized area  470 . In the illustrated embodiment, the mating zone  354  is essentially planar from the protrusion  370  to at least the localized area  470 . As the primary contact zone  418  slides (or wipes) along the first runway  332 , the primary contact zone  420  slides (or wipes along) the second runway  334 . The first contact finger  408  experiences an additional deflection as the first contact finger  408  engages the resonance-control zone  352  (or the protrusion  370 ). In the illustrated embodiment, the second contact finger  410  does not experience an additional deflection because the runway  334  does not include a protrusion. 
     Due to the resonance-control zone  352  (or the protrusion  370 ), the primary contact zone  418  of the first contact finger  408  may be deflected away from the first runway  332 . After the primary contact zone  418  clears the protrusion  370 , the engagement surface  409  may engage and slide along the protrusion  370 . To reduce the likelihood of the primary contact zone  418  being separate from the mating zone of the first runway  332 , the first contact finger  408  may be shaped to extend inwardly toward the first runway  332 . For example, a proximate section  460  of the first contact finger  408  that includes the contoured end segment  432  may be bent toward the first runway  332  at a point  462 . The proximate section  460  may be bent to a greater degree than a similar section of the second contact finger  410 . 
     Alternatively or in addition to the proximate section  460 , the contoured end segment  432  and/or an interior surface  442  of the connector housing  440  may be shaped to reduce the likelihood of the primary contact zone  418  being separate from the first runway  332  during operation. For example, the contoured end segment  432  may be blocked from moving during the mating operation by the interior surface  442  of the connector housing  440 . The contoured end segment  432  and/or the interior housing  440  may be shaped such that the contoured end segment  432  is either (a) separate from the interior surface  442  prior to the mating operation and then engages the interior surface  442  during the mating operation or (b) engaged with (e.g., pressed against) the interior surface prior to the mating operation. Because the contoured end segment  432  is blocked by the connector housing  440 , the portion of the first contact finger  408  between the primary contact zone  418  and the stub-contact zone  424  may not move away from the first runway  332 . More specifically, the interior surface  442  of the connector housing  440  may block movement of the contoured end segment  432  away from the first runway  332  while permitting the first contact finger  408  to bow as the resonance-control zone  352  (or the protrusion  370 ) slidably engages the engagement surface  409  of the first contact finger  408 . 
     In some embodiments, the contoured end segment  434  of the second contact finger  410  is separated from the interior surface  442  of the connector housing  440  by a flex gap  466 . The flex gap  466  permits movement of the second contact finger  410  during the mating operation. Permitting the second contact finger  410  to move may reduce the mating force necessary for mating the electrical contact  300  with the first contact finger  408 . For example, the first contact finger  408  may be blocked from moving by the connector housing  440  as described herein. Unlike other electrical contacts, the electrical contact  300  engages the first contact finger  408  at two separates points (e.g., the primary contact zone  418  and the stub-contact zone  424 ). The frictional forces generated by the first contact finger  408  and the first runway  332  of the electrical contact  300  may be greater when the first contact finger  408  is not permitted to be deflected further away. In such instances, the flex gap  466  (and compliance of the second contact finger  410 ) may enable a mating operation that requires less force. 
     In some embodiments, the electrical contact  300  and/or the connector housing (not shown in  FIG. 7 ) that is coupled to the electrical contact  300  may permit at least some deflection of the electrical contact  300  in a direction toward the second contact finger  410 . The flex gap  466  (and compliance of the second contact finger  410 ) may permit the deflection of the electrical contact  300  without a significant increase in the frictional forces generated. Frictional forces generated between the first contact finger  408  and the electrical contact  300  may be reduced by permitting the electrical contact  300  to be deflected toward the second contact finger  410 . 
     In the illustrated embodiment, the electrical contact  300  includes a stub portion  480 . The stub portion  480  is defined between the resonance-control zone  352  and the first contact end  302 . Without the resonance-control zone  352  (or the protrusion  370 ), the stub portion of the electrical contact  300  would extend from the first contact end  302  to the primary contact zone  418 . Accordingly, the contact  402  may engage the electrical contact  300  at two different areas along the same surface thereby reducing the size of an electrical path taken by reflected energy. As such, embodiments provide a mechanism for controlling or reducing the electrical length of the stub portion while also allowing a wipe distance that is within tolerances. 
       FIGS. 8 and 9  are enlarged views of a mating pin  510  of an electrical contact  500 . The electrical contact  500  may be similar to the electrical contact  300  ( FIG. 4 ). For example, the electrical contact  500  may be stamped-and-formed from sheet metal  558 . Before or after shaping the sheet metal  558 , the sheet metal  558  may be coated with a material to form a contact plating  559 . The contact plating  559  may comprise, for instance, a gold alloy. One or more additional layers (not shown) may exist that define the sheet metal  558  and/or the contact plating  559 . Like the electrical contact  300 , the electrical contact  500  includes a wipe zone  530 , a resonance-control zone  532 , and a mating zone  534  along the mating pin  510 . 
     The mating pin  510  may include first and second panel sections  562 ,  564  that are coupled to one another and folded about a common fold edge  566 . A contact gap  568  exists between the first and second panel sections  562 ,  564 . The panel section  562  includes a first runway  532  and has a first panel edge  563 , and the panel section  564  includes a second runway  534  and a second panel edge  565  ( FIG. 8 ). The mating pin  510  includes an elongated opening or void  590  that extends lengthwise along the mating pin  510  and partially separates the panel section  562  and the fold edge  566 . The elongated opening  590  defines a bow region  592  of the panel section  562 . 
     The bow region  592  bridges different portions of the panel section  562 . The bow region  592  has a length that extends between a panel joint  593  and a panel joint  595 . The bow region  592  has a width that extends between opposite edge portions  598 ,  599 . The edge portion  598  is a portion of the panel edge  563 , and the edge portion  599  partially defines the elongated opening  590 . The bow region  592  includes at least a portion of the wipe zone  530 , the resonance-control zone  532 , and the mating zone  534 . As shown in  FIGS. 8 and 9 , the bow region  592  also includes a protrusion  570 . The protrusion  570  is a localized region of the bow region  592  that is bent outwardly. 
     The bow region  592  may be configured to reduce a mating force that resists the mating operation. More specifically, the resonance-control zone  532  (or the protrusion  570 ) and the other contact, such as the electrical contact  402 , generate frictional forces during the mating operation. These frictional forces resist the mating operation or, in other words, increase the amount of force necessary to fully mate the electrical connectors. Collectively, the frictional forces from each electrical contact  500  may render the mating operation difficult to fully complete. 
     The bow region  592  may reduce these frictional forces while maintaining contact between the resonance-control zone  552  and the other contact. The bow region  592  is more compliant (or capable of being deflected) than panel sections that do not include the bow region. During the mating operation, the bow region  592  permits the protrusion  570  to be deflected inward such that a size of the contact gap  568  is reduced. More specifically, the bow region  592  bends or bows inward relative to the panel joints  593 ,  595  during the mating operation (as indicated by the arrow  580  in  FIG. 8 ). The bow region  592  is more compliant or flexible than panel sections that do not include the bow region. By allowing the bow region  592  to be deflected inward, the frictional forces between the resonance-control zone  532  (or the protrusion  570 ) and the other contact may be reduced. 
     It should 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. 
     As used in the description, the phrase “in an exemplary embodiment” and/or the like means that the described embodiment is just one example. The phrase is not intended to limit the inventive subject matter to that embodiment. Other embodiments of the inventive subject matter may not include the recited feature or structure. 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.