Patent Publication Number: US-2020295483-A1

Title: Electrical connector system

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to electrical connector systems. 
     Some communication systems utilize communication connectors, such as card edge connectors to interconnect various components of the system for data communication. Some known communication systems use pluggable modules, such as I/O modules, that are electrically connected to the card edge connectors. The pluggable modules have module circuit boards having card edges that are mated with the card edge connectors during the mating operation. The module circuit boards are typically limited to two rows of contacts with a first row of the contacts on the upper surface of the module circuit board and with a second row of the contacts on the lower surface of the module circuit board. As such, the density of the communication system is limited by the mating interface defined by the card edge connector and the module circuit board. 
     A need remains for a communication system having improved contact density to handle a greater number of high-speed signals transmitted through the communication system. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical connector system is provided including a circuit card assembly and a pluggable module. The circuit card assembly including a host circuit board, a socket connector mounted to the host circuit board, and a guide rail extending along the host circuit board. The host circuit board has a contact array of circuit board contacts on an upper surface of the host circuit board. The socket connector has a socket substrate having an upper contact array of upper contacts and a lower contact array of lower contacts electrically connected to corresponding upper contacts. The upper contacts have mating interfaces being accessible from above the socket connector and being coplanar. The lower contacts are electrically connected to corresponding circuit board contacts. The guide rail has a guide feature and a module actuator. The pluggable module includes a module body having a top and a bottom extending between a front and a rear. The module body has a longitudinally extending guide feature operatively engaging the guide rail to guide mating of the module body with the guide rail in a module mating direction parallel to the upper surface of the host circuit board. The module body has a window at the bottom proximate to the rear. The pluggable module includes a module circuit board held by the module body having a module contact array of module contact pads aligned with the window with the module contacts exposed from below the module body for mating with corresponding upper contacts of the circuit card assembly. The pluggable module includes an actuation feature associated with the module body engaging the module actuator of the circuit card assembly to force mating of the module contacts with the upper contacts of the circuit card assembly in a contact mating direction transverse to the module mating direction. 
     In another embodiment, a circuit card assembly is provided including a host circuit board having a contact array of circuit board contacts on an upper surface of the host circuit board and a socket connector mounted to the upper surface of the host circuit board. The socket connector has a socket substrate having an upper contact array of upper contacts and a lower contact array of lower contacts electrically connected to corresponding upper contacts. The upper contacts have mating interfaces configured to be electrically connected to module contacts of a pluggable module mated to the circuit card assembly. The mating interfaces are accessible from above the socket connector and are coplanar for mating with the module contacts. The lower contacts are electrically connected to corresponding circuit board contacts. The circuit card assembly includes a guide rail extending along the upper surface of the host circuit board. The guide rail has a guide feature to guide mating of the pluggable module with the socket connector in a module mating direction parallel to the upper surface of the host circuit board. The guide rail has a module actuator configured to engage the pluggable module and move the pluggable module in a contact mating direction transverse to the module mating direction. The module actuator forces the module contacts to mate with the upper contacts in the contact mating direction. 
     In a further embodiment, a pluggable module is provided including a module body extending between a front and a rear and having a top and a bottom between the front and the rear. The module body has a longitudinally extending guide feature to guide mating of the module body with a guide feature of a circuit card assembly in a module mating direction. The module body has a window at the bottom proximate to the rear. The pluggable module includes a module circuit board held by the module body having a mating edge between an upper surface and a lower surface. The module circuit board has a module contact array of module contact pads at the lower surface proximate to the mating edge. The module contact array is aligned with the window at the bottom of the module body with the module contacts exposed from below the module body for mating with corresponding contacts of the circuit card assembly. The pluggable module includes an actuation feature associated with the module body. The actuation feature is configured to engage an actuation feature of the circuit card assembly to force mating of the module contacts with the contacts of the circuit card assembly in a contact mating direction transverse to the module mating direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an electrical connector system formed in accordance with an exemplary embodiment. 
         FIG. 2  is a front perspective view of a circuit card assembly of the electrical connector system in accordance with an exemplary embodiment. 
         FIG. 3  is an exploded view of a portion of the circuit card assembly in accordance with an exemplary embodiment. 
         FIG. 4  is an enlarged perspective view of a portion of the circuit card assembly showing a portion of a socket connector in accordance with an exemplary embodiment. 
         FIG. 5  is a top perspective view of the socket connector in accordance with an exemplary embodiment. 
         FIG. 6  is a bottom perspective view of the socket connector in accordance with an exemplary embodiment. 
         FIG. 7  is a front perspective view of a pluggable module of the electrical connector system in accordance with an exemplary embodiment. 
         FIG. 8  is a rear perspective view of the pluggable module in accordance with an exemplary embodiment. 
         FIG. 9  is a bottom perspective view of the pluggable module in accordance with an exemplary embodiment. 
         FIG. 10  is a schematic illustration of an exemplary pinout in accordance with an exemplary embodiment. 
         FIG. 11  illustrates the pluggable module at a first stage of mating in accordance with an exemplary embodiment. 
         FIG. 12  illustrates the pluggable module at a second stage mating in accordance with an exemplary embodiment. 
         FIG. 13  illustrates the pluggable module at a third stage of mating in accordance with an exemplary embodiment. 
         FIG. 14  illustrates the pluggable module at a fourth stage of mating in accordance with an exemplary embodiment. 
         FIG. 15  illustrates the pluggable module at a fifth stage of mating in accordance with an exemplary embodiment. 
         FIG. 16  illustrates the pluggable module at a sixth stage of mating in accordance with an exemplary embodiment. 
         FIG. 17  is a cross sectional view of the electrical connector system showing the pluggable module partially mated with the circuit card assembly in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a front perspective view of an electrical connector system  100  formed in accordance with an exemplary embodiment. The electrical connector system  100  includes a circuit card assembly  102  and a pluggable module  104  mated with the circuit card assembly  102 . In various embodiments, multiple pluggable modules  104  may be mated with the circuit card assembly  102 . The pluggable modules  104  may be I/O modules forming part of a communication system, such as a server or network switch. The pluggable modules  104  may be removably coupled to the circuit card assembly  102 . 
     The circuit card assembly  102  includes a tray  106  at a bottom of the circuit card assembly  102  and a panel  108  at a front of the circuit card assembly  102 . The circuit card assembly  102  includes a host circuit board  110  held by the tray  106 . Optionally, multiple host circuit boards  110  may be held by the tray  106 . The tray  106  may be loaded into a rack or cabinet of a communication system, such as a rack or cabinet of a server or network switch. The circuit card assembly  102  includes a socket connector  112  (shown in  FIG. 2 ) mounted to the host circuit board  110 . Multiple socket connectors  112  may be mounted to the host circuit board  110 , such as for interfacing with corresponding pluggable modules  104 . The pluggable modules  104  are electrically connected to the host circuit board  110  through the socket connectors  112 . 
     The circuit card assembly  102  includes guide rails  114  extending along the host circuit board  110  for guiding mating of the pluggable modules  104  with the socket connectors  112 . In various embodiments, the circuit card assembly  102  includes backer plates  116  used to provide mechanical support to the board and to secure the guide rails  114  to the host circuit board  110 , such as using fasteners passing through the host circuit board  110 . In other various embodiments, rather than using the backer plates  116 , guide rails  114  may be coupled to the bottom of the host circuit board  110  for receiving pluggable modules  104  on both sides of the host circuit board  110  in a belly-to-belly mounting arrangement. 
     In the illustrated embodiment, the panel  108  includes a plurality of panel openings  120  defining ports configured to receive corresponding pluggable modules  104 . The pluggable modules  104  extend through the panel  108  for mating with the circuit card assembly  102 . A portion of the pluggable module  104  is loaded rearward of the panel  108  for interfacing with the socket connector  112 . A portion of the pluggable module  104  is located forward of the panel  108  for access by an operator. For example, plug connectors  122  may be plugged into the pluggable modules  104 . The cables  124  extend from the plug connectors  122 . In alternative embodiments, the cables  124  may extend into the pluggable module  104  for direct electrical connection to the pluggable module  104  and not be detachable. 
       FIG. 2  is a front perspective view of the circuit card assembly  102  in accordance with an exemplary embodiment.  FIG. 3  is an exploded view of a portion of the circuit card assembly  102  in accordance with an exemplary embodiment. In the illustrated embodiment, five socket connectors  112  are mounted to the host circuit board  110 . Greater or fewer socket connectors  112  may be provided in alternative embodiments. The guide rails  114  are provided for each of the socket connectors  112  to guide mating of the pluggable module  104  (shown in  FIG. 1 ) with the corresponding socket connector  112 . In various embodiments, the guide rails  114  are provided between the socket connectors  112  such that each guide rail  114  is capable of guiding pluggable modules  104  on both sides thereof. In other various embodiments, to guide rails  114  may be provided for each socket connector  112  and arranged back to back or spaced apart depending on the particular application and desired spacing. 
     The host circuit board  110  includes an upper surface  200  and a lower surface  202  extending between a front  204  and a rear  206  of the host circuit board  110 . The socket connectors  112  and the guide rails  114  are mounted to the upper surface  200  at or near the front  204 . Other locations are possible in alternative embodiments. The backer plates  116  may be used to secure the guide rails  114  to the host circuit board  110  using fasteners  118 . The backer plates  116  may provide rigidity for the host circuit board  110  in the vicinity of the socket connectors  112  to prevent or resist warping of the host circuit board  110  at the mounting locations of the socket connectors  112 . In various embodiments, the socket connectors  112  and the corresponding guide rails  114  may be provided on both the upper surface  200  and the lower surface  202  for receiving the pluggable modules  104  on both sides of the host circuit board  110  in the belly-to-belly mounting arrangement. 
     The host circuit board  110  includes a contact array (not shown) of circuit board contacts (not shown) on the upper surface  200 . The circuit board contacts may be defined by circuits of the host circuit board  110 , such as pads, vias, traces and the like. In an exemplary embodiment, the circuit board contacts are solder pads. In other various embodiments, the circuit board contacts are plated vias. 
     The guide rails  114  are mounted to the host circuit board  110  and form a module channel  220  that receives a corresponding pluggable module  104  in a module mating direction  222 . Optionally, the module mating direction  222  may be generally parallel to the upper surface  200  of the host circuit board  110 . For example, the module mating direction  222  may be generally horizontal. The guide rails  114  are provided on opposite sides of the module channel  220 . The socket connector  112  is located in the module channel  220  such as at or near a rear end of the module channel  220 . 
     In an exemplary embodiment, the circuit card assembly  102  includes a lifter spring  224  in the module channel  220  forward of the socket connector  112 . The lifter spring  224  is configured to lift the pluggable module  104  upward off the host circuit board  110  in a lifting direction  226  during mating of the pluggable module  104  with the circuit card assembly  102 . The lifting direction  226  may be an upward direction away from the upper surface  200  of the host circuit board  110 . The lifter spring  224  is used to protect the socket connector  112  during mating and un-mating of the pluggable module  104  with the socket connector  112 . By lifting the pluggable module  104  upward away from the socket connector  112 , the contacts of the pluggable module  104  and the socket connector  112  are protected from damage, wear and short-circuiting. 
     In an exemplary embodiment, the guide rail  114  guides the pluggable module  104  in a contact mating direction  228 , generally opposite the lifting direction  226  to seat the pluggable module  104  against the socket connector  112 . Contacts of the pluggable module  104  and the socket connector  112  are electrically connected when the pluggable module  104  is moved in the contact mating direction  228 . In an exemplary embodiment, the pluggable module  104  is moved in the contact mating direction  228  at the end of the loading process of the pluggable module  104  into the module channel  220 , such as when the pluggable module  104  is properly aligned with the socket connector  112 . 
     Each guide rail  114  includes a top  230  and a bottom  232  extending between a front  234  and a rear  236 . The bottom  232  is mounted to the upper surface  200  of the host circuit board  110 . The front  234  may be located at or near the front  204  of the host circuit board  110 . Optionally, the front  234  may extend forward of the front  204  of the host circuit board  110 . In other various embodiments, the front  234  may be recessed rearward of the front  204  of the host circuit board  110 . 
     The guide rail  114  includes a first side  240  and a second side  242 . Optionally, both sides  240 ,  242  may face corresponding module channels  220  for guiding corresponding pluggable modules  104 . In other various embodiments, only the first side  240  or the second side  242  may face the corresponding module channel  220  for interfacing with and guiding the corresponding pluggable module  104 . In an exemplary embodiment, the guide rail  114  includes guide features  244  on the first side  240  and/or the second side  242 . The guide features  244  guide mating of the pluggable module  104  with the circuit card assembly  102 . In an exemplary embodiment, the guide features  244  is a longitudinally extending rib  246  extending between the front  234  and the rear  236 . Other types of guide features may be used in alternative embodiments, such as a groove, a pin, a shoulder, and the like. Optionally, the rib  246  may be approximately centered between the top  230  and the bottom  232 . 
     The guide rail  114  includes an actuation feature configured to interface with the pluggable module  104  and control mating of the pluggable module  104  with the socket connector  112 . In an exemplary embodiment, the actuation feature is a module actuator  250 . In the illustrated embodiment, the module actuator  250  is located proximate to the rear  236  of the guide rail  114 . The module actuator  250  may be located at the top  230  of the guide rail  114 . In the illustrated embodiment, the module actuator  250  includes a roller bearing  252  rotatably coupled to the guide rail  114 . The roller bearing  252  rotates when engaging the pluggable module  104  to reduce mating friction with the pluggable module  104 . Other types of module actuators  250  may be provided in alternative embodiments, such as a cam element, a rocker element, a pin, a ramp, or another type of actuator. The module actuator  250  is used to position the pluggable module  104  relative to the socket connector  112 , such as for mating contacts of the pluggable module  104  with contacts of the socket connector  112 . The module actuator  250  may act on the pluggable module  104  in a direction non-parallel to, such as opposite to, the biasing force of the lifter spring  224 . For example, the lifter spring  224  may lift the pluggable module  104  upward in the lifting direction  226  while the module actuator  250  pushes the pluggable module  104  downward in the contact mating direction  228  as the pluggable module  104  is loaded into the module channel  220 . 
       FIG. 4  is an enlarged perspective view of a portion of the circuit card assembly  102  showing a portion of the socket connector  112  and the lifter spring  224  on the host circuit board  110 .  FIG. 5  is a top perspective view of the socket connector  112  in accordance with an exemplary embodiment.  FIG. 6  is a bottom perspective view of the socket connector  112  in accordance with an exemplary embodiment. 
     The socket connector  112  includes a socket substrate  260  having an upper contact array  262  of upper contacts  264  ( FIG. 5 ) and a lower contact array  266  of the lower contacts  268  ( FIG. 6 ). The socket substrate  260  extends between the upper surface  270  and a lower surface  272 . The socket substrate  260  extends between a front  274  of the socket connector  112  and a rear  276  of the socket connector  112 . In an exemplary embodiment, the socket substrate  260  is a circuit board. The socket substrate  260  includes circuits, such as pads, traces, vias and the like routed along one or more layers of the socket substrate  260 . For example, the socket substrate  260  may include plated vias extending between the upper surface  270  and the lower surface  272  for electrically connecting the upper contacts  264  with corresponding lower contacts  268 . In other various embodiments, the upper contacts  264  may extend entirely through the socket substrate  260  for directly connecting to the lower contacts  268 . In other various embodiments, the upper contacts  264  may be integral with corresponding lower contacts  268  is part of a unitary, monolithic contact structure arranged at both the upper surface  270  and the lower surface  272 . 
     The lower contacts  268  are configured to be electrically connected with corresponding circuit board contacts of the host circuit board  110 . For example, the lower contacts  268  may be soldered to the circuit board contacts. In an exemplary embodiment, the lower contacts  268  are solder balls. The lower contact array  266  is a ball grid array. Other types of contacts may be provided in alternative embodiments. 
     The upper contacts  264  are configured to interface with the pluggable module  104 . In an exemplary embodiment, the upper contacts  264  are spring contacts having mating interfaces  278  configured to be mated with the pluggable module  104 . The spring contacts are deflectable when mated with the pluggable module  104 . For example, the pluggable module  104  may be coupled to the socket connector  112  from above to compress the upper contacts  264  causing the mating interfaces  278  to be spring biased against the pluggable module  104 . In an exemplary embodiment, the mating interfaces  278  are co-planer for mating with the pluggable module  104  from above. In various embodiments, the upper contacts  264  are soldered to corresponding conductors of the socket substrate  260  at the upper surface  270 . In other various embodiments, the upper contacts  264  are press-fit into vias of the socket substrate  260 . 
     In an exemplary embodiment, the socket connector  112  includes a socket frame  280  coupled to the socket substrate  260 . In the illustrated embodiment, the socket frame  280  is coupled to the upper surface  270  of the socket substrate  260 . In other various embodiments, the socket frame  280  may enclosed the socket substrate  260 , such as along the sides and/or the ends of the socket substrate  260 . The socket frame  280  may be coupled to the host circuit board  110  in various embodiments, such as to secure the socket substrate  260  relative to the host circuit board  110 . The socket frame  280  surrounds a socket cavity  282  around the upper contacts  264 . The socket frame  280  includes a support surface  284  at a top of the socket frame  280 . The support surface  284  may support the pluggable module  104  to prevent the pluggable module  104  from over compressing or damaging the upper contacts  264 . The socket frame  280  limits compression of the upper contacts  264  by the pluggable module  104 . In an exemplary embodiment, the socket frame  280  is a plastic frame having frame members surround the socket cavity  282 . For example, the frame members may extend along both sides and both ends of the socket substrate  260  to form a rectangular socket cavity  282 . The socket cavity  282  may have other shapes in alternative embodiments. The socket frame  280  may have other frame members extending across the socket cavity  282  in alternative embodiments. 
     In an exemplary embodiment, the lifter spring  224  includes a base  290  and a spring member  292  extending from the base  290 . The base  290  is mounted to the host circuit board  110 . The spring member  292  extends upward from the base  290  between a fixed end  294  and a free end  296 . The spring member  292  is folded over at the fixed end  294 . The spring member  292  may be bent or curved to form a lifting surface  298  between the fixed end  294  and the free end  296 . The lifting surface  298  is configured to engage the pluggable module  104  to lift the pluggable module  104  away from the host circuit board  110 . 
       FIG. 7  is a front perspective view of the pluggable module  104  in accordance with an exemplary embodiment.  FIG. 8  is a rear perspective view of the pluggable module  104  in accordance with an exemplary embodiment.  FIG. 9  is a bottom perspective view of the pluggable module  104  in accordance with an exemplary embodiment. 
     The pluggable module  104  includes a module body  300  holding a module circuit board  302  ( FIG. 9 ). The module body  300  extends between a front  304  and a rear  306 . In an exemplary embodiment, the pluggable module includes an actuation feature  308  at or near the rear  306 . The rear  306  of the pluggable module  104  is configured to be loaded into the circuit card assembly  102  for mating with the circuit card assembly  102 . The actuation feature  308  is used to position the pluggable module  104  for mating with the socket connector  112  (shown in  FIG. 4 ). The module body  300  includes a top  310  and a bottom  312 . The module body  300  includes a first side  314  and a second side  316 . In the illustrated embodiment, the pluggable module  104  includes a pair of the actuation features  308  at the rear  306  at the first side  314  and the second side  316 . The actuation features  308  are exposed at the top  310 . The actuation features  308  may be located at other locations in alternative embodiments. 
     In an exemplary embodiment, the module body  300  includes guide features  320  configured to interact with the guide features  244  of the guide rail  114  (shown in  FIG. 4 ) to guide mating of the module body  300  with the circuit card assembly  102 . Optionally, the guide features  320  extend longitudinally along the sides  314 ,  316  between the front  304  and the rear  306 . In the illustrated embodiment, the guide features  320  include channels  322  along the first and second sides  314 ,  316 . The channels  322  receive the ribs  246  (shown in  FIG. 4 ) of the guide rails  114 . Other types of guide features may be provided in alternative embodiments, such as ribs, pins, shoulders, and the like. In the illustrated embodiment, the channels  322  are open at the rear  306  for receiving the ribs  246  when the pluggable module  104  is mated with the circuit card assembly  102 . 
     In an exemplary embodiment, the module body  300  includes a cavity  330  ( FIG. 9 ) that receives the module circuit board  302 . The module body  300  includes a window  332  open at the bottom  312  to expose the module circuit board  302  in the cavity  330 . Optionally, the window  332  may be located proximate to the rear  306 . In an exemplary embodiment, the module body  300  includes a lip  334  that transitions from the window  332  to a pocket  336  formed in the bottom  312  forward of the window  332 . The pocket  336  includes a platform  338  that is recessed below the bottom  312 . The lip  334  transitions to the platform  338 . The pocket  336  is configured to receive the lifter spring  224  (shown in  FIG. 4 ). The lifter spring  224  is configured to engage the platform  338  to lift the pluggable module  104  during mating with the circuit card assembly  102 . 
     The module circuit board  302  includes a mating edge  340  ( FIG. 9 ) extending between an upper surface  342  (shown in  FIG. 11 ) and a lower surface  344 . The lower surface  344  is exposed in the window  332  ( FIG. 9 ) at the bottom  312  of the module body  300 . The module circuit board  302  includes a module contact array  346  of module contacts  348  at the lower surface  344  proximate to the mating edge  340 . In an exemplary embodiment, the module contacts  348  are defined by circuits of the module circuit board  302 , such as pads, traces, vias, and the like. In alternative embodiments, the module contacts  348  may be spring beam contacts having deflectable spring beams defining a compressible mating interface. The module contacts  348  are arranged in a plurality of rows and a plurality of columns. In an exemplary embodiment, the module contacts  348  are arranged in greater than three rows and arranged in greater than three columns. In the illustrated embodiment, the module contacts  348  are arranged in fourteen rows and sixty five columns; however, the module contacts  348  may be arranged in greater or fewer rows and in greater or fewer columns. Having a large number of rows and/or columns provides a dense mating interface for the pluggable module  104  having many high-speed signal lines through the pluggable module  104 . 
     In an exemplary embodiment, the pluggable module  104  includes one or more optical connectors  350  at the front  304 . The optical connectors  350  are configured to receive the optical plug connectors  122  (shown in  FIG. 1 ). The optical connectors  350  are optically connected to the module circuit board  302 . In alternative embodiments, the cables  124  (shown in  FIG. 1 ) may be directly terminated to the module circuit board  302 , such as being terminated to optical components that are attached to the module circuit board  302 . Alternately, the connectors  350  could be electrical connectors and the plug connectors could be high speed electrical connectors terminated to high performance differential pair cables. 
     In an exemplary embodiment, the pluggable module  104  includes a heat sink  352  at the top  310 . The heat sink  352  includes a plurality of heat dissipating fins  354  extending along the top  310 . The heat dissipating fins  354  may extend longitudinally between the front  304  and the rear  306 . In an exemplary embodiment, the pluggable module  104  includes a flange  356  at the front  304 . The flange  356  includes openings  358  that are open to the channels between the heat dissipating fins  354 . The openings  358  allow airflow through the flange  356  for cooling the heat dissipating fins  354 . 
     The actuation features  308  transitions the generally horizontal loading of the pluggable module  104  into a generally vertical mating of the pluggable module  104 . In an exemplary embodiment, the actuation feature  308  includes a cam surface  360 . Optionally, the cam surface  360  may be non-planar. The cam surface  360  may be nonparallel to the bottom  312  of the module body  300 . When the cam surface  360  interfaces with the module actuator  250 , the pluggable module  104  is moved in the contact mating direction  228 . For example, the horizontal loading of the pluggable module  104  in the module mating direction  222  is transferred to at least partial vertical movement of the pluggable module  104  in the contact mating direction  228 . The cam surface  360  forces the rear  306  of the module body  300  downward for mating the module contacts  348  with the upper contacts  264  (shown in  FIG. 4 ) of the circuit card assembly  102 . In an exemplary embodiment, the actuation feature  308  includes a detent  362  defined by a bump  364  and a pocket  366  forward of the bump  364 . The bump  364  is located forward of a rear platform  368  at the rear  306 . The bump  364  is elevated relative to the rear platform  368 . When the module actuator  250  transitions from the rear platform  368  along the bottom  312  into the pocket  366 , the rear  306  of the module body  300  is moved downward to compress the module contacts  348  against the upper contacts  264 . Other types of actuation features  308  may be provided in alternative embodiments. For example, the actuation features  308  may be cam followers, slots, pins, rockers, and the like. 
       FIG. 10  is a schematic illustration of an exemplary pinout or contact layout for the pluggable module  104  ( FIG. 9 ), the socket connector  112  ( FIG. 4 ), and the host circuit board  110  ( FIG. 3 ). The pinout illustrates conductors in an array arranged in a plurality of rows and a plurality of columns. Greater or fewer rows and greater or fewer columns may be used in other pinout embodiments. 
     The pinout illustrates power conductors P, power return conductors R, low speed signal conductors L, high speed signal conductors H, and ground conductors G. in the illustrated embodiment, the low speed signal conductors L, the power conductors P, and the power return conductors R are provided in the first row. The ground conductors G and the high-speed signal conductors H are provided in the second through fourteenth rows. Optionally, the high-speed signal conductors H are arranged in pairs that are surrounded by corresponding ground conductors G. in the illustrated embodiment, the pinout includes one hundred and twenty eight differential pairs. 
       FIGS. 11 through 16  illustrate the electrical connector system  100  showing the pluggable module  104  process stages of being mated with the circuit card assembly  102  in accordance with an exemplary embodiment.  FIG. 11  illustrates the pluggable module  104  at a first stage of mating.  FIG. 12  illustrates the pluggable module  104  at a second stage mating.  FIG. 13  illustrates the pluggable module  104  at a third stage of mating.  FIG. 14  illustrates the pluggable module  104  at a fourth stage of mating.  FIG. 15  illustrates the pluggable module  104  at a fifth stage of mating.  FIG. 16  illustrates the pluggable module  104  at a sixth stage of mating.  FIG. 16  illustrates the pluggable module  104  fully mated with the circuit card assembly  102 . 
     The pluggable module  104  is initially loaded into the module channel  220  between the guide rails  114  ( FIG. 11 ). The pluggable module  104  is loaded through the panel opening  120  in the panel  108  to interface with the guide rails  114 . The guide rails  114  position the pluggable module  104  such that the bottom  312  of the module body  300  slides just above the upper surface  200  of the host circuit board  110 . The guide features  244  of the guide rail  114  generally prevent the module body  300  from touching the upper surface  200  of the host circuit board  100  and prevent lift off of the pluggable module  104  from the host circuit board  110 . 
     As the pluggable module  104  is advanced ( FIG. 12 ) in the module mating direction  222 , the pluggable module  104  eventually interfaces with the lifter spring  224 . The lifter spring  224  engages the lip  334  forward of the window  332 . As the pluggable module  104  is further advanced ( FIG. 13 ) in the module mating direction  222 , the lifter spring  224  is received in the pocket  336  and engages the platform  338 . The lifting surface  298  of the lifter spring  224  presses upward against the platform  338  to lift the pluggable module  104  upward in the lifting direction  226 . The spring member  292  of the lifter spring  224  may be partially compressed by the weight of the pluggable module  104 . The lifter spring  224  lifts the rear  306  of the module body  300  and the module circuit board  302  to a clearance position above the socket connector  112 . The lower surface  344  of the module circuit board  302  is lifted to a vertical height above the mating interfaces  278  of the upper contacts  264 . As such, further advancement of the pluggable module  104  is performed clear of the mating interfaces  278  of the upper contacts  264 . Excessive wear or damage to the upper contacts  264  due to loading of the pluggable module  104  is reduced or eliminated because of the clearance between the module circuit board  302  and the upper contacts  264 . Further advancement of the pluggable module  104  in the module mating direction  222  occurs with the pluggable module  104  in the lifted position. 
     As the pluggable module  104  is further advanced ( FIG. 14 ) in the module mating direction  222 , the rear  306  of the module body  300  engages the module actuator  250 . The module actuator  250  interfaces with the actuation feature  308  of the pluggable module  104  to position the pluggable module  104  relative to the socket connector  112 . The roller bearing  252  of the module actuator  250  initially engages the rear platform  368  along the top  310  of the module body  300  ( FIG. 14 ). The lifter spring  224  holds the pluggable module  104  in the lifted position to provide clearance between the module circuit board  302  and the upper contacts  264  of the socket connector  112 . Further advancement of the pluggable module  104  in the module mating direction  222  advances the bump  364  toward the roller bearing  252  ( FIG. 15 ). When the roller bearing  252  engages the bump  364 , the pluggable module  104  is almost fully loaded into the circuit card assembly  102  in the module mating direction  222 . The module circuit board  302  has advanced over the socket connector  112 . The module circuit board  302  is located directly vertically above the upper contacts  264 . 
     When the pluggable module  104  is advanced to the fully mated position ( FIG. 16 ), the module actuator  250  operably engages the actuation feature  308  of the pluggable module  104  to position the pluggable module  104  relative to the circuit card assembly  102 . The module actuator  250  engages the actuation feature  308  to force mating of the module contacts  348  ( FIG. 9 ) of the module circuit board  302  with the upper contacts  264  of the socket connector  112  of the circuit card assembly  102 . The module actuator  250  forces the pluggable module  104  to move in the contact mating direction  228 . The roller bearing  252  engages the cam surface  360  to guide mating in the contact mating direction  228 . The roller bearing  252  forces the module body  300  downward to compress the upper contacts  264 . The roller bearing  252  forces the module body  300  to compress the lifter spring  224 . The bump  364  is forced under the roller bearing  252  as the pluggable module  104  is loaded rearward in the module mating direction  222 . The downward movement of the module body  300  transfers the module circuit board  302  downward toward the socket connector  112 . The module contacts  348  are mated with the upper contacts  264  in the contact mating direction  228  transverse to the module mating direction  222 . The cam surface  360  transfers the generally horizontal loading of the pluggable module  104  to the generally vertical mating of the module contacts  348  with the upper contacts  264 . The upper contacts  264  are arranged in a horizontal array and the module contacts  348  are arranged in a horizontal array that compresses the upper contacts  264  in a generally vertical contact mating direction  228 . Other types of actuation features may be used in alternative embodiments to control mating of the pluggable module  104  with the socket connector  112 . 
     The interaction between the lifter spring  224  and the pluggable module  104  protects the upper contacts  264  from damage, wear, and short-circuiting by providing clearance between the module circuit board  302  and the upper contacts  264  as the module circuit board  302  is loaded in the rearward module mating direction  222  until the module circuit board  302  is generally aligned vertically above the upper contacts  264 . The module actuator  250  controls movement of the pluggable module  104  in the contact mating direction  228  once the pluggable module  104  is properly positioned relative to the socket connector  112 . The open mating interface of the socket connector  112  and the open mating interface of the pluggable module  104  at the bottom  312  of the module body  300  allows connection of many rows of contacts at a compressible, separable interface, which is in contrast to conventional card edge connectors and circuit cards that limit the contacts to 1 or 2 upper row(s) and 1 or 2 lower row(s) on opposite sides of a circuit card. 
       FIG. 17  is a cross sectional view of the electrical connector system  100  showing the pluggable module  104  partially mated with the circuit card assembly  102 , such as at the stage of mating shown in  FIG. 15 . The lifter spring  224  ( FIG. 13 ) lifts the rear  306  of the module body  300  and the module circuit board  302  to a clearance position above the socket connector  112 . The lower surface  344  of the module circuit board  302  is lifted to a vertical height above the mating interfaces  278  of the upper contacts  264 . Advancement of the pluggable module  104  is performed clear of the mating interfaces  278  of the upper contacts  264 . Excessive wear or damage to the upper contacts  264  due to loading of the pluggable module  104  is reduced or eliminated because of the clearance between the module circuit board  302  and the upper contacts  264 . Advancement of the pluggable module  104  in the module mating direction  222  occurs with the pluggable module  104  in the lifted position. 
     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.