Patent Publication Number: US-11025004-B2

Title: Circuit card assemblies for a communication system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit to U.S. Provisional Application No. 62/543,072, filed Aug. 9, 2017, titled “CIRCUIT CARD ASSEMBLIES FOR A COMMUNICATION SYSTEM”, the subject matter of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to circuit card assemblies for communication systems. 
     Communication systems are in use in various applications, such as network switches. The communication systems include various circuit cards, such as backplanes and/or daughtercards, which are coupled together to electrically connect various circuits. For example, the circuit cards include electrical connectors that are mated to electrical connectors of one or more other circuit cards. Some communication systems use a backplane or midplane that is perpendicular to the mating direction of the daughtercards. However, such backplanes or midplanes block airflow through the communication system leading to overheating of components or limiting operating speeds to avoid overheating. 
     Other communication systems arrange both circuit cards parallel to the mating direction to allow airflow through the system. The circuit cards are typically oriented perpendicular to each other (for example, horizontally and vertically). The electrical connectors are provided at edges of both circuit cards and direct mate to each other. Conventional communication systems utilize right angle electrical connectors on both cards that direct mate with each other in an orthogonal orientation. The mating interfaces of the electrical connectors are parallel to the mating edges of the circuit cards such that the electrical connectors are mated in a direction parallel to the mating direction of the circuit cards. However, such right angle electrical connectors are expensive to manufacture and occupy a large amount of space in the system, thus blocking airflow through the system. 
     A need remains for a cost effective and reliable communication system allowing airflow through the communication system for cooling the electrical components. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a communication system is provided including a first circuit card assembly and a second circuit card assembly. The first circuit card assembly includes a first printed circuit board (PCB) and a first electrical connector mounted to the first PCB, the first electrical connector having a first mating end and first contacts at the first mating end, each of the first contacts having a first mating interface, the first electrical connector having a receptacle housing and a mating housing received in the receptacle housing and being movable in the receptacle housing in a connector mating direction along a connector mating axis. The second circuit card assembly includes a second PCB and a second electrical connector mounted to the second PCB, the second electrical connector having a second mating end and second contacts at the second mating end, each of the second contacts having a second mating interface, the second electrical connector having a header housing holding the second contacts. At least one of the first PCB and the second PCB includes a slot receiving the other of the first PCB and the second PCB in a board loading direction along a board loading axis. The receptacle housing is coupled to the header housing in the board loading direction as the first PCB and the second PCB are mated, and wherein the mating housing is movable within the receptacle housing toward the header housing in the connector mating direction generally perpendicular to the board loading direction. 
     In another embodiment, a circuit card assembly for a communication system is provided including a printed circuit board (PCB) having a first surface and a second surface and a mating edge between the first and second surfaces. The PCB having a slot extending inward from the mating edge configured to receive a second PCB of a second circuit card assembly in a board loading direction perpendicular to the mating edge. The PCB has a mounting area on the first surface adjacent the slot. The circuit card assembly includes an electrical connector mounted to the first surface at the mounting area configured for mating with a second electrical connector of the second circuit card assembly. The electrical connector includes a receptacle housing mounted to the PCB and a mating housing received in the receptacle housing and being movable relative to the receptacle housing. The electrical connector extends between a front and a rear with the front being provided proximate to the mating edge. The electrical connector includes a mounting end extending between the front and the rear being mounted to the mounting area. The electrical connector includes a mating end extending between the front and the rear. The mating housing is provided at the mating end being configured to be mated to the second electrical connector. The electrical connector has contacts held by the mating housing and being movable relative to the receptacle housing with the mating housing. The receptacle housing is configured to be coupled to the second electrical connector as the second PCB is loaded in the board loading direction. The mating housing is movable within the receptacle housing toward the second electrical connector in a connector mating direction generally perpendicular to the board loading direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a communication system formed in accordance with an exemplary embodiment. 
         FIG. 2  is a perspective view of a portion of the communication system showing a first circuit card assembly coupled to a second circuit card assembly. 
         FIG. 3  is a top view of a portion of the communication system showing the first circuit card assembly poised for mating with the second circuit card assembly. 
         FIG. 4  is a top view of a portion of the communication system showing the first circuit card assembly mated to the second circuit card assembly. 
         FIG. 5  is a perspective view of a portion of the communication system showing the first circuit card assembly and the second circuit card assembly poised for mating. 
         FIG. 6  is a perspective view of a portion of the communication system in accordance with an exemplary embodiment. 
         FIG. 7  is a perspective view of a portion of the communication system in accordance with an exemplary embodiment. 
         FIG. 8  is a top perspective view of a portion of the first circuit card assembly showing the first electrical connector mounted to a first PCB. 
         FIG. 9  is a bottom view of a first electrical connector of the first circuit card assembly in accordance with an exemplary embodiment. 
         FIG. 10  is a perspective view of a portion of the first electrical connector in accordance with an exemplary embodiment. 
         FIG. 11  is an end view of a portion of the first electrical connector in accordance with an exemplary embodiment. 
         FIG. 12  is a partial sectional view of a portion of the first electrical connector in accordance with an exemplary embodiment. 
         FIG. 13  is a perspective view of a portion of the second circuit card assembly in accordance with an exemplary embodiment. 
         FIG. 14  is a perspective view of a portion of the second electrical connector in accordance with an exemplary embodiment. 
         FIG. 15  illustrates a portion of the communication system showing a portion of the first electrical connector mated with the second electrical connector. 
         FIG. 16  is a top perspective, partial sectional view of a portion of the communication system showing a portion of the first electrical connector partially mated with the second electrical connector. 
         FIG. 17  is a top perspective, partial sectional view of a portion of the communication system showing a portion of the first electrical connector partially mated with the second electrical connector. 
         FIG. 18  is a cross-sectional view of a portion of the connector system showing a portion of the first electrical connector partially mated with the second electrical connector. 
         FIG. 19  is a perspective, partial sectional view of a portion of the connector system showing a portion of the first electrical connector partially mated with the second electrical connector. 
         FIG. 20  is a top perspective, partial sectional view of a portion of the communication system showing a portion of the first electrical connector mated with the second electrical connector. 
         FIG. 21  is a cross-sectional view of a portion of the connector system showing a portion of the first electrical connector mated with the second electrical connector. 
         FIG. 22  is a perspective, partial sectional view of a portion of the connector system showing a portion of the first electrical connector mated with the second electrical connector. 
         FIG. 23  is a perspective view of a portion of the connector system in accordance with an exemplary embodiment showing a portion of the first electrical connector and a portion of the second electrical connector. 
         FIG. 24  is a perspective view of a portion of the connector system in accordance with an exemplary embodiment showing a portion of the first electrical connector and a portion of the second electrical connector. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a communication system  100  formed in accordance with an exemplary embodiment. The communication system  100  includes a chassis  102  having a frame  104  configured to hold communication components, such as network components, such as circuit card assemblies. Optionally, the chassis  102  may include a cabinet (not shown) surrounding components of the communication system  100 . In an exemplary embodiment, the frame  104  includes a plurality of racks  106 ,  108  for holding circuit card assemblies. For example, the communication system  100  may form part of a data center switch having one or more backplanes and/or daughter cards, such as line cards, switch cards or other types of circuit cards that may be electrically connected together. 
     In an exemplary embodiment, the communication system  100  includes a front end  110  and a rear end  112 . The racks  106  are provided at the front end  110  and the racks  108  are provided at the rear end  112 . One or more circuit card assemblies  120  may be received in the racks  106  at the front end  110  and one or more circuit card assemblies  122  may be received in the racks  108  at the rear end  112 . The circuit card assemblies  120  may be referred to hereinafter as first circuit card assemblies  120  or front circuit card assemblies to differentiate from the circuit card assemblies  122 , which may be referred to hereinafter as second circuit card assemblies  122  and/or rear circuit card assemblies  122 . In an exemplary embodiment, the circuit card assemblies  120 ,  122  are orthogonal to each other. For example, in the illustrated embodiment, the front circuit card assemblies  120  are oriented horizontally while the rear circuit card assemblies  122  are oriented vertically; however, other orientations are possible in alternative embodiments. 
     The front circuit card assemblies  120  are electrically connected to one or more of the rear circuit card assemblies  122 . Optionally, the front circuit card assemblies  120  and/or the rear circuit card assemblies  122  may be removable from the corresponding racks  106 ,  108 . The racks  106 ,  108  guide and position the circuit card assemblies  120 ,  122 , respectively. For example, the racks  106  position the front circuit card assemblies  120  for mating with multiple rear circuit card assemblies  122  and the racks  108  position the rear circuit card assemblies  122  for mating with multiple front circuit card assemblies  120 . The front circuit card assemblies  120  may be loaded into the frame  104  through the front end  110  while the rear circuit card assemblies  122  may be loaded into the frame  104  through the rear end  112 . For example, the front circuit card assemblies  120  are configured to be loaded into corresponding racks  106  in a loading direction  124  and the rear circuit card assemblies  122  are configured to be loaded into corresponding racks  108  in a loading direction  126 . The loading directions  124 ,  126  may be parallel to a loading axis  128 . 
     The first circuit card assembly  120  includes a first printed circuit board (PCB)  200  and a first electrical connector  202  mounted to the first PCB  200 . The first PCB  200  may include any number of the electrical connectors  202 , such as one electrical connector  202  for electrically connecting to each corresponding second circuit card assembly  122 . Optionally, the first PCB  200  may include one or more first slots  204  for receiving PCBs of corresponding second circuit card assemblies  122  when mated thereto. 
     The first PCB  200  extends between a first mating edge  206  at a front of the PCB  200  and a rear edge  208  opposite the mating edge  206 . Optionally, the rear edge  208  may include a handle or other feature for insertion and removal of the first circuit card assembly  120 . The first PCB  200  may include one or more electrical components  210  (such as shown in  FIG. 2 ) thereon. For example, the electrical components  210  may be processors, memory modules, batteries, fans, signal processing devices, and the like. 
     The second circuit card assembly  122  includes a second PCB  300  and a second electrical connector  302  mounted to the second PCB  300 . The second PCB  300  may include any number of the electrical connectors  302 , such as one electrical connector  302  for electrically connecting to each corresponding first circuit card assembly  120 . The second PCB  300  extends between a second mating edge  306  at a front of the PCB  300  and a rear edge  308  opposite the mating edge  306 . The first and second mating edges  206 ,  306  of the first and second PCBs  200 ,  300  interface with each other when the first and second circuit card assemblies  120 ,  122  are mated. For example, the fronts of the PCBs  200 ,  300  face each other and the rear edges  208 ,  308  face away from each other. Optionally, the rear edge  308  may include a handle or other feature for insertion and removal of the second circuit card assembly  122 . The second PCB  300  may include one or more electrical components  310  (such as shown in  FIG. 2 ) thereon. For example, the electrical components  310  may be processors, memory modules, batteries, fans, signal processing devices, and the like. 
     Optionally, the second PCB  300  may include one or more second slots  304  for receiving first PCBs  200  of corresponding first circuit card assemblies  120  when mated thereto. In various embodiments, both PCBs  200 ,  300  include the first and second slots  204 ,  304 . In other various embodiments, only the first PCB  200  includes the first slots  204 , whereas in other various embodiments, only the second PCB  300  includes the second slots  304 . 
     The first slots  204  and/or the second slots  304  allow the first and second PCBs  200 ,  300  to be internested and overlapping such that the first and second electrical connectors  202 ,  302  are aligned for mating. For example, the first slots  204  and/or the second slots  304  allow the first and second PCBs  200 ,  300  to overlap to align mating ends of the first and second electrical connectors  202 ,  302  for mating. The arrangement allows the first and second electrical connectors  202 ,  302  to be mated in a mating direction perpendicular to the loading directions  124 ,  126 . During mating, the first and second PCBs  200 ,  300  and the first and second electrical connectors  202 ,  302  may be loaded or mated together in a board loading direction  130  ( FIG. 2 ) and at the end of the mating process the first and second electrical connectors  202 ,  302  may be mated in a connector mating direction  132  ( FIG. 2 ) perpendicular to the board loading direction  130 . 
     Having the first and second circuit card assemblies  122  internested and overlapped using the slot(s)  204 ,  304  allows the first and second electrical connectors  202 ,  302  to be elongated along the PCBs  200 ,  300  reducing one or more other dimensions of the electrical connectors  202 ,  302  (for example, a height and/or a width) allowing a greater amount of airflow through the communication system  100  (for example, from the front end  110  to the rear end  112  and/or from the rear end  112  to the front end  110 . The arrangement may allow the PCBs  200 ,  300  to overlap to reduce one or more dimensions of the communication system  100 , such as a front to rear length of the communication system  100 . 
       FIG. 2  is a perspective view of a portion of the communication system  100  showing the first circuit card assembly  120  coupled to the second circuit card assembly  122 ; however, it is noted that the first circuit card assembly  120  may be designed to be coupled to multiple circuit card assemblies and/or the second circuit card assembly  122  may be designed to be coupled to multiple circuit card assemblies, such as in the arrangement illustrated in  FIG. 1 .  FIG. 3  is a top view of a portion of the communication system  100  showing the first circuit card assembly  120  poised for mating to the second circuit card assembly  122 .  FIG. 4  is a top view of a portion of the communication system  100  showing the first circuit card assembly  120  coupled to the second circuit card assembly  122 .  FIG. 5  is a perspective view of a portion of the communication system  100  showing the first circuit card assembly  120  and the second circuit card assembly  122  poised for mating. 
     The terms “first”, “second”, etc. are used merely as labels to generally identify components of the first circuit card assembly  120  or the second circuit card assembly  122 , respectively; however, such labels are not used exclusively with the circuit card assemblies  120 ,  122 . Either or both of the circuit card assemblies  120 ,  122  may include any of the various components or elements described herein and some components may only be described with respect to either the circuit card assembly  120  or the circuit card assembly  122 ; however, the other of the circuit card assembly  120  or the circuit card assembly  122  may additionally include such components. Furthermore, the components may be described herein with or without the “first” label or the “second” label. 
     The first circuit card assembly  120  includes the first PCB  200  having the first slot  204  and the electrical connector  202  mounted to the PCB  200  proximate to the first slot  204 . The PCB  200  includes a first surface  212  and a second surface  214  being the main surfaces of the PCB  200 . In the illustrated embodiment, the first surface  212  is an upper surface and the second surface  214  is a lower surface; however, the PCB  200  may have other orientations in alternative embodiments. The first and second surfaces  212 ,  214  extend along a primary axis  216  and a secondary axis  218  perpendicular to the primary axis  216 . The PCB  200  has a thickness between the first and second surfaces  212 ,  214  along a transverse axis  217  perpendicular to the primary and secondary axes  216 ,  218 . In an exemplary embodiment, the primary and secondary axes  216 ,  218  are in a horizontal plane and the transverse axis  217  extends in a vertical direction; however, the PCB  200  may have other orientations in alternative embodiments. In an exemplary embodiment, the primary axis  216  extends between the mating edge  206  and the rear edge  208  (shown in  FIG. 1 ). In an exemplary embodiment, the secondary axis  218  is parallel to the mating edge  206 . 
     The first slot  204  extends entirely through the PCB  200  between the first and second surfaces  212 ,  214 . The first slot  204  is open at the mating edge  206  to receive the second circuit card assembly  122 . The first slot  204  extends a length along the primary axis  216  to an end edge  220  (shown in  FIGS. 4 and 5 ) remote from the mating edge  206 . The first slot  204  has first and second side edges  222 ,  224  extending between the mating edge  206  and the end edge  220 . Optionally, the side edges  222 ,  224  may be generally parallel to each other. Alternatively, the side edges  222 ,  224  may be nonparallel, such as to taper the first slot  204 . For example, the first slot  204  may be wider near the mating edge  206  and narrower near the end edge  220 . Optionally, the side edges  222 ,  224  may have chamfered lead-ins at the mating edge  206  to guide the second circuit card assembly  122  into the first slot  204 . 
     The first PCB  200  includes a mounting area  230  for the electrical connector  202  on the first surface  212 . The mounting area  230  is adjacent the first slot  204 . For example, the mounting area  230  extends along the mating edge  206  a distance from the first slot  204  and extends along the first side edge  222  of the first slot  204  a distance from the mating edge  206 . Optionally, the mounting area  230  may extend beyond the end edge  220  of the first slot  204 . The electrical connector  202  is terminated to the PCB  200  at the mounting area  230 . For example, contacts  228  that extend through the electrical connector  202  may be soldered to the PCB  200  at the mounting area  230 . The mounting area  230  may include plated vias that receive compliant pins or solder tails of the contacts  228  of the electrical connector  202  for termination of the contacts  228  to the PCB  200 . Optionally, at least a portion of the electrical connector  202  may extend beyond the first side edge  222  over the first slot  204  and/or at least a portion of the electrical connector  202  may extend forward of the mating edge  206  and/or at least a portion of the electrical connector  202  may extend rearward of the end edge  220 . In other various embodiments, the PCB  200  may include more than one mounting area  230  adjacent the first slot  204  for receiving additional electrical connectors  202 . For example, multiple electrical connectors  202  may be electrically connected to the same circuit card assembly  122 . For example, additional electrical connectors  202  may be provided on both sides of the first slot  204  and/or both sides of the PCB  200 . 
     The first electrical connector  202  is mounted to the PCB  200  at the mounting area  230 . In the illustrated embodiment, the electrical connector  202  is a right angle connector having a mounting end  232  perpendicular to a mating end  234 . For example, the mounting end  232  may be provided at a bottom of the electrical connector  202  and the mating end  234  may be provided at a side of the electrical connector  202 . The electrical connector  202  extends between a front  236  and a rear  238  opposite the front  236 . The mounting end  232  extends between the front  236  and the rear  238  at the bottom of the electrical connector  202 . The mounting end  232  is mounted to the PCB  200 . For example, the electrical connector  202  is mechanically and electrically terminated to the PCB  200  at the mounting end  232 . The mating end  234  extends between the front  236  and the rear  238 . In the illustrated embodiment, the mating end  234  generally faces the first slot  204  for interfacing with the second electrical connector  302  when the second circuit card assembly  122  is received in the first slot  204 . The mating end  234  is configured to be mated to the mating electrical connector defined by the second electrical connector  302  when the second circuit card assembly  122  is received in the first slot  204 . 
     In an exemplary embodiment, the mating end  234  is oriented generally vertically along the transverse axis  217  and extends parallel to the primary axis  216 . The mating end  234  faces sideways rather than forward. For example, the mating end  234  is perpendicular to the mating edge  206  of the PCB  200 . The front  236  is oriented generally vertically along the transverse axis  217  and extends parallel to the secondary axis  218 . The front  236  may be positioned a first distance from the mating edge  206  (either forward of, rearward of or flush with the mating edge  206 ) and the rear  238  is positioned a second distance from the mating edge  206  greater than the first distance. The mating end  234  spans a majority of the distance between the front  236  and the rear  238 . The front  236  is forward facing and, in the illustrated embodiment, is provided near the mating edge  206 , such as generally flush with the mating edge  206 . 
     The second circuit card assembly  122  includes the second PCB  300 , which may or may not include a slot. In the illustrated embodiment, the PCB  300  does not include a slot. The PCB  300  includes a first surface  312  and a second surface  314  being the main surfaces of the PCB  300 . In the illustrated embodiment, the first surface  312  defines a first side and the second surface  314  defines a second side of the PCB  300 ; however, the PCB  300  may have other orientations in alternative embodiments. The first and second surfaces  312 ,  314  extend along a primary axis  316  and a secondary axis  318  perpendicular to the primary axis  316 . The PCB  300  has a thickness between the first and second surfaces  312 ,  314  along a transverse axis  317  perpendicular to the primary and secondary axes  316 ,  318 . In an exemplary embodiment, the primary and secondary axes  316 ,  318  are in a vertical plane and the transverse axis  317  extends in a horizontal direction; however, the PCB  300  may have other orientations in alternative embodiments. In an exemplary embodiment, the primary axis  316  extends between the mating edge  306  and the rear edge  308  (shown in  FIG. 1 ). In an exemplary embodiment, the secondary axis  318  is parallel to the mating edge  306 . 
     In an exemplary embodiment, at least a portion of the PCB  300  is configured to be received in the first slot  204  that may at least partially fill the first slot  204 . Such portion may engage the end edge  220 , the first side edge  222  and/or the second side edge  224  of the first slot  204  when received therein. 
     The second PCB  300  includes a mounting area  330  for the electrical connector  302  on the first surface  312 . The mounting area  330  extends from the mating edge  306  a distance. The electrical connector  302  is terminated to the PCB  300  at the mounting area  330 . For example, contacts  328  of the electrical connector  302  may be soldered to the PCB  300  at the mounting area  330 . The mounting area  330  may include plated vias that receive compliant pins or solder tails of the contacts  328  of the electrical connector  302  for termination of the contacts  328  to the PCB  300 . Optionally, at least a portion of the electrical connector  302  may extend forward of the mating edge  306 . In other various embodiments, the PCB  300  may include more than one mounting area  330  for receiving additional electrical connectors  302 . For example, multiple electrical connectors  302  may be electrically connected to the same circuit card assembly  122 . 
     The second electrical connector  302  is mounted to the PCB  300  at the mounting area  330 . In the illustrated embodiment, the electrical connector  302  is a header connector having a mounting end  332  parallel to a mating end  334 . For example, the mounting end  332  may be provided along one side of the electrical connector  302  and the mating end  334  may be provided at the opposite side of the electrical connector  302 . Optionally, the mounting end  332  and the mating end  334  may be parallel to each other and non-coplanar. The electrical connector  302  extends between a front  336  ( FIG. 3  and a rear  338  ( FIG. 3 ) opposite the front  336 . The mounting end  332  and the mating end  334  both extend between the front  336  and the rear  338 . The mounting end  332  is mounted to the PCB  300 . For example, the electrical connector  302  is mechanically and electrically terminated to the PCB  300  at the mounting end  332 . In the illustrated embodiment, the mating end  334  is oriented for interfacing with the first electrical connector  202  when the second circuit card assembly  122  is received in the first slot  204 . 
     In an exemplary embodiment, the mating end  334  is oriented generally vertically and extends parallel to the primary axis  316 . The mating end  334  faces sideways rather than forward. For example, the mating end  334  is perpendicular to the mating edge  306  of the PCB  300 . The front  336  is oriented generally vertically and extends parallel to the secondary axis  318 . The front  336  may be positioned a first distance from the mating edge  306  (either forward of, rearward of or flush with the mating edge  306 ) and the rear  338  is positioned a second distance from the mating edge  306  greater than the first distance. The mating end  334  spans a majority of the distance between the front  336  and the rear  338 . The front  336  is forward facing and, in the illustrated embodiment, is provided near the mating edge  306 , such as generally flush with the mating edge  306 . 
     When the first and second circuit card assemblies  120 ,  122  are mated, the first and second PCBs  200 ,  300  are internested and the second PCB  300  is received in the first slot  204 . When mated, the first PCB  200  at least partially overlaps with the second PCB  300  to align the mating ends  234 ,  334  of the electrical connectors  202 ,  302 . For example, the mating edges  206 ,  306  bypass each other as the second PCB  300  is received in the first slot  204 . During mating, the contacts  328  are moved in a board loading direction  130  (for example, parallel to the primary axis  316  of the PCB  300 ) and the contacts  228  are moved in a connector mating direction  132  (for example, sideways or perpendicular to the board loading direction  130 ) as the first and second electrical connectors  202 ,  302  are mated. For example, a portion of the first electrical connector  202  is moved toward the second electrical connector  302 . 
       FIG. 6  is a perspective view of a portion of the communication system  100  in accordance with an exemplary embodiment.  FIG. 6  shows the second circuit card assembly  122  with the second slot  304  and the first circuit card assembly  120  without the first slot  204  (shown in  FIG. 5 ). Optionally, at least a portion of the first PCB  200  is configured to at least partially fill the second slot  304 . The second electrical connector  302  is mounted to the mounting area  330  adjacent the second slot  304 . When the first and second circuit card assemblies  120 ,  122  are mated, the first and second PCBs  200 ,  300  are internested with the first PCB  200  being received in the second slot  304 . When mated, the first PCB  200  at least partially overlaps with the second PCB  300  to align the mating ends  234 ,  334  of the electrical connectors  202 ,  302 . For example, the mating edges  206 ,  306  bypass each other as the first PCB  200  is received in the second slot  304 . 
       FIG. 7  is a perspective view of a portion of the communication system  100  in accordance with an exemplary embodiment.  FIG. 7  shows the first circuit card assembly  120  with the first slot  204  and the second circuit card assembly  122  with the second slot  304 . When the first and second circuit card assemblies  120 ,  122  are mated, the first and second PCBs  200 ,  300  are internested with the first PCB  200  being received in the second slot  304  and with the second PCB  300  being received in the first slot  204 . When mated, the first PCB  200  at least partially overlaps with the second PCB  300  to align the mating ends  234 ,  334  of the electrical connectors  202 ,  302 . For example, the mating edges  206 ,  306  bypass each other as the PCBs  200 ,  300  are received in the second and first slots  304 ,  204 , respectively. 
       FIG. 8  is a side perspective view of the first electrical connector  202  in accordance with an exemplary embodiment.  FIG. 9  is a bottom view of the first electrical connector  202  in accordance with an exemplary embodiment.  FIG. 10  is a perspective view of a portion of the first electrical connector  202  in accordance with an exemplary embodiment.  FIG. 11  is a side perspective view of a portion of the first electrical connector  202  in accordance with an exemplary embodiment. 
     In an exemplary embodiment, the first electrical connector  202  includes a mating housing  240  at the mating end  234  and a receptacle housing  241  (shown in cross section in  FIG. 9  and removed in  FIG. 10  to illustrate other components) surrounding at least a portion of the mating housing  240 . The mating housing  240  is movable within the receptacle housing  241 , such as in the connector mating direction  132 . Such movement allows mating of the first contacts  228  with the second contacts  328  (see  FIG. 13 ) of the second electrical connector  302 . 
     The mating housing  240  includes a first side  242 , a second side  244 , a front  246  and a rear  248 . The first side  242  defines the mating end  234  of the electrical connector  202 . The mating end  234  is oriented perpendicular to the first PCB  200 . In an exemplary embodiment, the mating housing  240  holds the contacts  228  for mating with the second electrical connector  302  (shown in  FIG. 2 ). For example, each of the contacts  228  includes a mating end  264  ( FIG. 11 ) extending beyond the first side  242  for mating with the second electrical connector  302 . The mating ends  264  are provided at the first side  242  in a predetermined layout for mating with the second electrical connector  302 . The mating ends  264  have mating interfaces  266  ( FIG. 11 ) configured to engage the mating contact  328  (shown in  FIG. 13 ) when mated thereto. Other types of mating ends may be provided in alternative embodiments, such as spring beams, pins, sockets, and the like. 
     The receptacle housing  241  includes end walls  243  extending between a front wall  245  and a rear wall  247 . The walls  243 ,  245 ,  247  define a cavity  249  that receives the mating housing  240 . In an exemplary embodiment, the end walls  243  are provided at a top  250  and a bottom  252  of the first electrical connector  202 . In an exemplary embodiment, the first electrical connector  202  include connecting elements  254  ( FIG. 11 ) at the top  250  and the bottom  252  for connecting the first electrical connector  202  to the second electrical connector  302 . In the illustrated embodiment, the connecting elements  254  are defined by grooves  256  in the receptacle housing  241  at the top  250  and the bottom  252  configured to receive portions of the second electrical connector  302 . The connecting elements  254  secure the receptacle housing  241  to the second electrical connector  302  as the electrical connectors  202 ,  302  are coupled together (for example, as the PCBs  200 ,  300  are moved in the board loading direction). Other types of connecting elements  254  may be provided in alternative embodiments, such as pins, clips, fasteners, and the like. 
     The electrical connector  202  includes drive members  258  ( FIG. 8 ) at the top  250  and the bottom  252  for actuating the mating housing  240  relative to the receptacle housing  241  during mating. The drive members  258  may be positioned in the cavity  249 , such as at the end wall(s)  243  at the top  250  and/or at the bottom  252 . The drive members  258  are operably coupled to the receptacle housing  241  and operably coupled to the mating housing  240 . As the drive members  258  are operated, the drive members  258  move the mating housing  240  sideways relative to the receptacle housing  241  in the connector mating direction  132 . In an exemplary embodiment, the drive members  258  may be actuated by engagement with the second electrical connector  302  as the first and second electrical connectors  302  are coupled together. For example, actuators, such as ramps, may be provided on the second electrical connector  302  to actuate the drive members  258  as the drive members engage the actuators. In an exemplary embodiment, multiple drive members  258  are provided, such as at a front section  260  and a rear section  262  of the electrical connector  202 . More than two drive members  258  may be provided along either or both sides of the electrical connector  202 . In an exemplary embodiment, the drive members  258  are cam levers and may be referred to hereinafter as cam levers  258 . However, other types of drive members  258  may be provided in alternative embodiments, such as cam pins configured to be received in cam sockets, pinions configured to engage a rack, a crank configured to engage a rack, a crank configured to engage an idler gear, one or more linkages configured to engage an actuator, and the like. 
     In an exemplary embodiment, the electrical connector  202  includes contact modules  270  each holding a plurality of the contacts  228 . The contact modules  270  may be coupled to the receptacle housing  241  and/or the mating housing  240 , such as at the second side  244 . For example, in the illustrated embodiment, the contact modules  270  are loaded into the receptacle housing  241  behind the mating housing  240 . In an exemplary embodiment, each contact module  270  includes a dielectric body  272  holding corresponding contacts  228 . For example, the dielectric body  272  may be overmolded around portions of the contacts  228 . Optionally, the contact modules  270  may include ground shields (not shown) to provide electrical shielding for the contacts  228 . 
     The contact modules  270  each have a first side  274  facing the mating housing  240  and a second side  276  opposite the first side  274 . The contact module  270  includes sides  278  facing each other when the contact modules  270  are stacked front to rear within the electrical connector  202 . Any number of the contact modules  270  may be stacked together depending on the particular application. The number of contacts  228  within the electrical connector  202  may be increased or decreased by changing the number of contact modules  270  rather than retooling to increase the number of contacts per contact module, as is common in conventional systems, such retooling being expensive. The contact module  270  includes a top  280  and a bottom  282 . The bottom  282  is configured to be mounted to the first PCB  200  ( FIG. 8 ). Optionally, portions of the contacts  228  may extend below the bottom  282  for termination to the first PCB  200 . For example, each of the contacts  228  may include a terminating end  284  ( FIG. 9 ) configured to be terminated to the first PCB  200 . For example, the terminating end  284  may be a compliant pin, such as an eye of the needle pin, configured to be press-fit into plated vias in the first PCB  200 . In other various embodiments, the terminating end  284  may be a solder tail or another type of terminating end. 
     In an exemplary embodiment, the electrical connector  202  includes a compliant section  286  between the contact modules  270  and the mating housing  240  that allows the mating housing  240  to shift relative to the contact modules  270 , such as during mating with the second electrical connector  302 . For example, the contact modules  270  may not engage the mating housing  240  in various embodiments. Rather, a gap  288  may be provided between the first sides  274  of the contact modules  270  and the second side  244  of the mating housing  240 . The contacts  228  may span the gap  288  between the contact modules  270  and the mating housing  240 . The contacts  228  include flexible sections  290  between the mating ends  264  and the terminating ends  284  to allow relative movement of the contacts  228  and the mating housing  240 . The flexible sections  290  may be defined by sections of the contacts  228  that are not encased or enclosed by the dielectric body  272  and/or do not extend through the mating housing  240 . For example, the flexible sections  290  may be located in the gap  288 . Optionally, the flexible sections  290  may be enclosed or shrouded by a portion of the electrical connector  202 , such as a shroud extending from the second side  244  of the mating housing  240  or a separate housing component. 
     In an exemplary embodiment, the contacts  228  include signal contacts  292  and ground contacts  294 . Optionally, the signal contacts  292  may be arranged in pairs  296  configured to convey differential signals. The ground contacts  294  are interspersed with the signal contacts  292  to provide electrical shielding for the signal contacts  292 . For example, the ground contacts  294  may be provided between the pairs  296  of signal contacts  292 . Optionally, the ground contacts  294  may be provided above, below, and/or between the various pairs  296  of signal contacts  292 . The signal contacts  292  and/or the ground contacts  294  may be stamped and formed contacts. 
     As shown in  FIG. 8 , the bottoms  282  of the contact modules  270  are mounted to the PCB  200 . In an exemplary embodiment, the mating housing  240  is positioned above the first slot  204  for mating with the second electrical connector  302  (shown in  FIG. 2 ). In an exemplary embodiment, the mating housing  240  is movable relative to the PCB  200  and the contact modules  270 , which are fixed to the PCB  200 . For example, the flexible sections  290  of the contacts  228  defining the compliant section  286  of the electrical connector  202  allow the mating housing  240  to move relative to the PCB  200  during mating with the second electrical connector  302 . 
       FIG. 12  is a rear perspective, partial sectional view of a portion of the first electrical connector  202 .  FIG. 12  shows the mating housing  240  positioned in the cavity  249 . The drive members  258  are positioned between the mating housing  240  and the receptacle housing  241 . In the illustrated embodiment, the drive members  258  are cam levers having a body  400  extending between a first side  402  and a second side  404 . The cam levers  258  includes a fixed pivot  406  extending from the second side  404  and a movable pivot  408  extending from the first side  402 . The fixed pivot  406  is received in an elongated slot  410  in the corresponding end wall  243  of the receptacle housing  241 . The movable pivot  408  is received in an opening  412  in the mating housing  240 . The cam levers  258  are pivotable about the fixed pivot  406  to cause the movable pivot  408  to move relative to the receptacle housing  241 . As the movable pivot  408  moves relative to the receptacle housing  241 , the mating housing  240  moves relative to the receptacle housing  241  in the connector mating direction  132 . 
       FIG. 13  is a perspective view of a portion of the second circuit card assembly  122  in accordance with an exemplary embodiment.  FIG. 14  is a perspective view of a portion of the second electrical connector  302  in accordance with an exemplary embodiment. In an exemplary embodiment, the electrical connector  302  includes a header housing  340  holding the contacts  328 . The header housing  340  includes walls defining a cavity  341  configured to receive the mating housing  240  of the first electrical connector  202  (both shown in  FIG. 8 ). 
     The header housing  340  includes a first side  342 , a second side  344 , a front  346  and a rear  348 . The first side  342  defines the mating end  334  of the electrical connector  302 . The mating end  334  is oriented parallel to the second PCB  300 . In an exemplary embodiment, the header housing  340  holds the contacts  328  for mating with the first electrical connector  202 . For example, each of the contacts  328  includes a mating end  364  ( FIG. 14 ) exposed at or beyond the first side  342  for mating with the first electrical connector  202 . The mating ends  364  are provided at the first side  342  in a predetermined layout for mating with the first electrical connector  202 . The mating ends  364  have mating interfaces  366  for electrical connection with the first contacts  228 . 
     The header housing  340  includes a top  350  and a bottom  352 . In an exemplary embodiment, the top  350  and the bottom  352  include connecting elements  354  for connecting the second electrical connector  302  to the first electrical connector  202 . In the illustrated embodiment, the connecting elements  354  include pockets  356  defined by ledges  355  at the top  350  and the bottom  352 . The pockets  356  are configured to receive corresponding connecting elements  254  (shown in  FIG. 8 ) of the receptacle housing  241  of the first electrical connector  202 . The ledges  355  are configured to be received in corresponding grooves  256  (shown in  FIG. 8 ). Other types of connecting elements  354  may be provided in alternative embodiments, such as pins, clips, fasteners, and the like. 
     The header housing  340  includes actuators  357  at the first side  342  configured to actuate the drive members  258  (shown in  FIG. 8 ). In the illustrated embodiment, the actuators  357  include ramp surfaces  358  and return ramp surfaces  359  that engage the drive members  258  and actuate the drive members  258  as the drive members  258  ride along the header housing  340  during mating of the first and second electrical connectors  202 ,  302  in the board loading direction  130 . In the illustrated embodiment, the header housing  340  includes multiple actuators  357  laterally spaced apart, such as for actuating multiple drive members  258 . For example, the header housing  340  may include actuators  357  along both the top  350  and the bottom  352  at both a front section  360  and a rear section  362  of the header housing  340 . Optionally, the actuators  357  may be at different heights, such as shorter at the front section  360  and taller at the rear section  362  to allow actuation of different drive members  258 . Optionally, the actuators  357  may be staggered within the cavity such as closer in or further out to align with corresponding staggered drive members  258 . 
     The header housing  340  defines the mounting end  332  of the electrical connector  302  configured to be mounted to the PCB  300 . Optionally, portions of the contacts  328  may extend beyond the mounting end  332  for termination to the PCB  300 . For example, the contacts  328  may include terminating ends (not shown), such as compliant pins, solder tails, and the like, configured to be terminated to the PCB  300 . 
     In an exemplary embodiment, such as shown in  FIG. 14 , the contacts  328  include signal contacts  392  and ground contacts  394 . Optionally, the signal contacts  392  may be arranged in pairs  396  configured to convey differential signals (differential pairs of signal contacts); however, the signal contacts  392  may convey single-ended signals rather than differential signals. The ground contacts  394  are interspersed with the signal contacts  392  to provide electrical shielding for the signal contacts  392 . For example, the ground contacts  394  may be provided between the pairs  396  of signal contacts  392 . 
       FIG. 15  illustrates a portion of the communication system  100  showing a portion of the first electrical connector  202  mated with the second electrical connector  302 .  FIG. 15  shows the mating housing  240  of the first electrical connector  202  and the cam levers  258  of the first electrical connector  202  mated with the header housing  340  of the second electrical connector  302 . The cam levers  258  engage corresponding actuators  357  when the first electrical connector  202  is coupled to the second electrical connector  302 . For example, as the first electrical connector slides into the second electrical connector  302  in the board loading direction  130 , the cam levers  258  slide along the ramp surfaces  358  of the actuators  357  causing the cam levers  258  to rotate. Rotation of the cam levers  258  causes movement of the mating housing  240  in the connector mating direction  132  to electrically connect the first contacts  228  and the second contacts  328 . 
       FIG. 16  is a top perspective, partial sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  partially mated with the second electrical connector  302 . During mating, the second electrical connector  302  is slid forward in the board loading direction  130  with the second PCB  300  into the slot  204  (shown in  FIG. 8 ) in the first PCB  200  (shown in  FIG. 8 ). The connecting elements  254  of the first electrical connector  202  to engage the connecting elements  354  of the second electrical connector  302 . For example, the ledge  355  is received in the groove  256 . A portion of the receptacle housing  241  is captured in the groove  356  behind the ledge  355 . 
     As such, the receptacle housing  241  is fixedly coupled to the header housing  340 . As the header housing  340  is slid forward in the board loading direction  130 , the actuators  357  are configured to interact with the cam levers  258 . In an exemplary embodiment, the actuators  357  are at different heights. For example, the actuator  357  at the front section  360  is shorter and the actuator  357  at the rear section  362  is taller. Optionally, the cam levers  258  may be staggered. For example, the cam lever  258  at the front section  260  is positioned further from the first side  242  and the cam lever  258  at the rear section  262  is positioned closer to the first side  242  ( FIG. 8 ). As such, the actuator  357  at the front section  360  does not interact with or actuate the cam lever  258  at the rear section  262  as the header housing  340  passes through the receptacle housing  241 . 
       FIG. 17  is a top perspective, partial sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  partially mated with the second electrical connector  302 .  FIG. 17  illustrates the first and second electrical connectors  202 ,  302  immediately before actuation of the cam levers  258 . The actuators  357  are illustrated immediately prior to engaging the cam levers  258 . In an exemplary embodiment, the cam levers  258  include cam surfaces  414  configured to engage the actuators  357 . The cam surfaces  414  are configured to ride along the ramp surfaces  358  as the header housing  340  is slid forward in the board loading direction  130 . 
       FIG. 18  is a cross-sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  partially mated with the second electrical connector  302 .  FIG. 19  is a perspective, partial sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  partially mated with the second electrical connector  302 .  FIGS. 18 and 19  illustrates the first electrical connector  202  positioned prior to actuation of the cam levers  258 . The mating housing  240  is elevated and separated from the header housing  340 . The cam levers  258  hold the mating housing  240  in a clearance position to allow the header housing  340  and the second contacts  328  to be loaded into the first electrical connector  202  in the board loading direction  130 . 
       FIG. 20  is a top perspective, partial sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  mated with the second electrical connector  302 .  FIG. 21  is a cross-sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  mated with the second electrical connector  302 .  FIG. 22  is a perspective, partial sectional view of a portion of the communication system  100  showing a portion of the first electrical connector  202  mated with the second electrical connector  302 .  FIGS. 20-22  illustrates the first and second electrical connectors  202 ,  302  after actuation of the cam levers  258 . 
     The actuators  357  are illustrated engaged with the cam levers  258 . During mating, the cam surfaces  414  ride along the ramp surfaces  358  of the actuators  357  to rotate the cam levers  258 . As the cam levers  258  rotate, the movable pivots  408  are pivoted and moved toward the header housing  340  in the connector mating direction  132 . During mating, the mating housing  240  is driven toward the header housing  340  in the connector mating direction  132  to mate the first contacts  228  and the second contacts  328 . In an exemplary embodiment, the header housing  340  includes stop surfaces  420  that stop mating of the mating housing  240  with the header housing  340 . The header housing  340  is driven in the board loading direction  130  until fully mated, Once the cam surfaces  414  clear the ramp surfaces  358 , the cam levers  258  are no longer rotated. Further travel of the header housing  340  causes the cam surfaces  414  to ride along the flat edge of the actuator  357  without further rotation of the cam levers  258 . Optionally, the header housing  340  may bottom out against the first electrical connector  202 , such as against the mating housing  240 . 
     Over travel of the header housing  340  in the board loading direction  130  causes the mating housing  240  and the cam levers  258  to move forward with the header housing  340 . The slot  410  in the receptacle housing  241  is elongated to allow the fixed pivots  406  to slide in the elongated slots  410 . Optionally, the receptacle housing  241  may include pockets  422  that receive portions of the cam levers  258  during over travel. During unmating of the first and second electrical connectors  202 ,  302 , a return cam surface  416  of the cam lever  258  engages the return ramp surface  359  of the actuator  357  to rotate the cam lever  258  in the opposite direction causing the mating housing  240  to move away from the header housing  340 . The header housing  340  may then be pulled out of the first electrical connector  202  during the unmating process. 
       FIG. 23  is a perspective view of a portion of the communication system  100  in accordance with an exemplary embodiment showing a portion of the first electrical connector  202  and a portion of the second electrical connector  302 . The first and second electrical connectors  202 ,  302  are similar to the embodiments described above; however, the first electrical connector  202  and the second electrical connector  302  include gears to actuate the mating housing  240  rather than cam levers. The drive member  258  in the illustrated embodiment includes a crank gear  430  having gear teeth  432 . The crank gear  430  includes a lever  434  operably coupled to the mating housing  240  and the receptacle housing  241 . The actuator  357  in the illustrated embodiment includes a rack  440  having gear teeth  442 . The crank gear  430  engages the rack  440  and is actuated to move the mating housing  240  relative to the receptacle housing  241  in the connector mating direction  132 . For example, the lever  434  may be rotated to move the mating housing  240 . Other types of gears may be provided in alternative embodiments, such as in idler gear, a worm gear or another type of gear. 
       FIG. 24  is a perspective view of a portion of the communication system  100  in accordance with an exemplary embodiment showing a portion of the first electrical connector  202  and a portion of the second electrical connector  302 . The first and second electrical connectors  202 ,  302  are similar to the embodiments described above; however, the first electrical connector  202  and the second electrical connector  302  include linkages to actuate the mating housing  240  rather than cam levers or gears. The drive member  258  in the illustrated embodiment includes a four bar linkage. The linkage is rotated to cause linear actuation of the mating housing  240  in the connector mating direction  132 . 
     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.