Patent Publication Number: US-9419380-B2

Title: Pluggable module for a communication system

Description:
BACKGROUND OF THE INVENTION 
     The subject matter described herein relates to a pluggable module for a communication system. 
     At least some known communication systems include receptacle assemblies, such as input/output (I/O) connector assemblies, that are configured to receive a pluggable module and establish a communicative connection between the pluggable module and an electrical connector of the receptacle assembly. As one example, a known receptacle assembly includes a receptacle housing that is mounted to a circuit board and configured to receive a small form-factor (SFP) pluggable transceiver. The receptacle assembly includes an elongated cavity that extends between an opening of the cavity and an electrical connector that is disposed within the cavity and mounted to the circuit board. The pluggable module is inserted through the opening and advanced toward the electrical connector in the cavity. The pluggable module and the electrical connector have respective electrical contacts that engage one another to establish a communicative connection. 
     One challenge often encountered in the design of the pluggable module and receptacle assembly is the heat generated during operation of the communication system, which negatively affects module/system reliability and electrical performance. Typically, heat is generated by components on the internal circuit board within the pluggable module and drawn away from the internal circuit board by the metal body of the pluggable module. In some cases, a heat sink that is held by the receptacle assembly housing in direct contact with the metal body of the pluggable module is used to transfer the heat from the pluggable module. Air flowing through and around the receptacle assembly transfers the heat that emanates from the pluggable module. As data throughput speeds of the pluggable modules increase, more heat is generated. Conventional designs are proving to be inadequate for the required heat transfer. 
     A further challenge in the design of the pluggable module and receptacle assembly is signal degradation due to electromagnetic interference (EMI). The receptacle housing is conductive and designed to reduce EMI along the signal paths. However, to reduce EMI, openings, slots, channels and other leakage areas are closed or eliminated, which reduces the amount of airflow through the receptacle housing available for heat dissipation. 
     Accordingly, there is a need for a pluggable module for use in a communication system that allows significant heat transfer and EMI reduction. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In an embodiment, a pluggable module is provided including a pluggable body extending between a mating end and a cable end. The pluggable body has a first end and an opposite second end with sides extending therebetween along a length of the pluggable body. The first end, second end and sides define a cavity. The pluggable body includes a plurality of fins extending outward from at least one of the first end, the second end and the sides. Channels are defined between the fins. The pluggable body has grid fins extending across the channels between adjacent fins. The pluggable module includes an internal circuit board held in the cavity. The internal circuit board is provided at an end of a cable communicatively coupled to the internal circuit board. The pluggable body is configured to be plugged into a receptacle assembly such that the internal circuit board is communicatively coupled to a communication connector of the receptacle assembly. 
     In a further embodiment, a pluggable module is provided including a pluggable body extending between a mating end and a cable end. The pluggable body has a first end and an opposite second end with sides extending therebetween along a length of the pluggable body. The first end, second end and sides define a cavity. The pluggable body includes a plurality of fins extending outward from at least one of the first end, the second end and the sides. Channels are defined between the fins. The fins are provided at the cable end of the pluggable body such that the fins allow airflow along the length of the pluggable body to an exterior environment beyond the cable end. The pluggable body has grid fins extending across the channels between adjacent fins. The grid fins are provided at a positon aligned with a faceplate through which the pluggable module is plugged. The pluggable module includes an internal circuit board held in the cavity. The internal circuit board is provided at an end of a cable communicatively coupled to the internal circuit board. The pluggable body is configured to be plugged into a receptacle assembly such that the internal circuit board is communicatively coupled to a communication connector of the receptacle assembly. 
     In a further embodiment, a communication system is provided including a pluggable module and a receptacle assembly. The pluggable module includes a pluggable body extending between a mating end and a cable end. The pluggable body has a first end and an opposite second end with sides extending therebetween along a length of the pluggable body. The first end, second end and sides define a cavity. The pluggable body has a plurality of fins extending outward from at least one of the first end, the second end and the sides. Channels are defined between the fins. The pluggable body has grid fins extending across the channels between adjacent fins. The pluggable module has an internal circuit board held in the cavity. The internal circuit board is provided at an end of a cable communicatively coupled to the internal circuit board. The receptacle assembly has a receptacle housing defining a module cavity with a port opening at a front end of the receptacle housing open to the module cavity. The front end of the receptacle housing is configured to be positioned within an opening of a faceplate. The module cavity receives the pluggable module through the port opening. The receptacle assembly has a communication connector within the receptacle housing at a rear end of the receptacle housing. The pluggable module is pluggably coupled to the communication connector such that the internal circuit board is communicatively coupled to the communication connector. The grid fins are positioned proximate to the front end such that the grid fins reduce electromagnetic interference (EMI) through the channels proximate to the front end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective cross-sectional view of a communication system in accordance with an embodiment. 
         FIG. 2  is a partially exploded view of a receptacle assembly of the communication system shown in  FIG. 1 . 
         FIG. 3  is a perspective view of a pluggable module of the communication system formed in accordance with an exemplary embodiment. 
         FIG. 4  is a front view of the pluggable module in accordance with an exemplary embodiment. 
         FIG. 5  is a front perspective view of the communication system showing the pluggable modules loaded in the receptacle assembly. 
         FIG. 6  is a front perspective view of the communication system showing the pluggable modules in accordance with an exemplary embodiment loaded in the receptacle assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments set forth herein include communication systems and pluggable modules of the same. The pluggable module provides significant thermal heat transfer for the components thereof. Various embodiments of the pluggable module include a pluggable body having a cost effective design. Various embodiments of the pluggable module include a pluggable body that facilitates heat transfer. Various embodiments of the communication system include heat sink inserts that guide loading of the pluggable module into a corresponding receptacle assembly and that transfer heat away from the pluggable module body. 
     Unlike conventional pluggable modules that utilize riding heat sinks that are held by a receptacle assembly and that interface with a flat upper surface of the pluggable module, embodiments set forth herein have fins integral with the pluggable module body that transfer heat therefrom. The fins may have air channels therebetween that are open and allow air to flow along the fins to cool the pluggable modules. In various embodiments, the channels may receive rails of a heat sink insert to allow direct thermal connection to the pluggable module by the heat sink to draw heat away from the pluggable module body to cool the pluggable module. 
       FIG. 1  is a perspective cross-sectional view of a communication system  100  in accordance with an embodiment. The communication system  100  may include a circuit board  102 , a receptacle assembly  104  mounted to the circuit board  102 , and one or more pluggable modules  106  that are configured to communicatively engage the receptacle assembly  104 . The communication system  100  is oriented with respect to a mating or insertion axis  91 , an elevation axis  92 , and a lateral axis  93 . The axes  91 - 93  are mutually perpendicular. Although the elevation axis  92  appears to extend in a vertical direction parallel to gravity in  FIG. 1 , it is understood that the axes  91 - 93  are not required to have any particular orientation with respect to gravity. Moreover, only one pluggable module  106  is shown in  FIG. 1 , but it is understood that multiple pluggable modules  106  may simultaneously engage the receptacle assembly  104 . 
     The communication system  100  may be part of or used with telecommunication systems or devices. For example, the communication system  100  may be part of or include a switch, router, server, hub, network interface card, or storage system. In the illustrated embodiment, the pluggable module  106  is configured to transmit data signals in the form of electrical signals. In other embodiments, the pluggable module  106  may be configured to transmit data signals in the form of optical signals. The circuit board  102  may be a daughter card or a mother board and include conductive traces (not shown) extending therethrough. 
     The receptacle assembly  104  includes a receptacle housing  108  that is mounted to the circuit board  102 . The receptacle housing  108  may also be referred to as a receptacle cage. The receptacle housing  108  may be arranged at a bezel or faceplate  109  of a chassis of the system or device, such as through an opening in the faceplate  109 . As such, the receptacle housing  108  is interior of the device and corresponding faceplate  109  and the pluggable module(s)  106  is loaded into the receptacle housing  108  from outside or exterior of the device and corresponding faceplate  109 . 
     The receptacle housing  108  includes a front end  110  and an opposite back end  112 . The front end  110  may be provided at, and extend through an opening in, the faceplate  109 . The mating axis  91  may extend between the front and back ends  110 ,  112 . Relative or spatial terms such as “front,” “back,” “top,” or “bottom” are only used to distinguish the referenced elements and do not necessarily require particular positions or orientations in the communication system  100  or in the surrounding environment of the communication system  100 . For example, the front end  110  may be located in or facing a back portion of a larger telecommunication system. In many applications, the front end  110  is viewable to a user when the user is inserting the pluggable module  106  into the receptacle assembly  104 . 
     The receptacle housing  108  is configured to contain or block electromagnetic interference (EMI) and guide the pluggable module(s)  106  during a mating operation. To this end, the receptacle housing  108  includes a plurality of housing walls  114  that are interconnected with one another to form the receptacle housing  108 . The housing walls  114  may be formed from a conductive material, such as sheet metal and/or a polymer having conductive particles. In the illustrated embodiment, the housing walls  114  are stamped and formed from sheet metal. In some embodiments, the receptacle housing  108  is configured to facilitate airflow through the receptacle housing  108  to transfer heat (or thermal energy) away from the receptacle assembly  104  and pluggable module(s)  106 . The air may flow from inside the receptacle housing  108  (for example, behind the faceplate  109 ) to the external environment (for example, forward of the faceplate  109 ) or from outside the receptacle housing  108  into the interior of the receptacle housing  108 . Fans or other air moving devices may be used to increase airflow through the receptacle housing  108  and over the pluggable module(s)  106 . 
     In the illustrated embodiment, the receptacle housing  108  includes a first (or bottom) row  116  of elongated module cavities  120  and a second (or top) row  118  of elongated module cavities  122 . Each of the module cavities  120 ,  122  extends between the front and back ends  110 ,  112 . The module cavities  120 ,  122  have respective port openings  121 ,  123  that are sized and shaped to receive a corresponding pluggable module  106 . The module cavities  120 ,  122  may have the same or similar dimensions and extend lengthwise in a direction that is parallel to the mating axis  91 . In the illustrated embodiment, each module cavity  122  is stacked over a corresponding module cavity  120  such that the module cavity  120  is positioned between the module cavity  122  and the circuit board  102 . Any number of module cavities may be provided including a single module cavity. 
     In some embodiments, the pluggable module  106  is an input/output cable assembly having a pluggable body  130 . The pluggable body  130  includes a mating end  132  and an opposite cable end  134 . A cable  136  is coupled to the pluggable body  130  at the cable end  134 . The pluggable body  130  also includes an internal circuit board  138  that is communicatively coupled to electrical wires or optical fibers (not shown) of the cable  136 . The cable  136  may be communicatively coupled by directly terminating the wires to the internal circuit board  138 , such as by soldering the wires to the internal circuit board. Alternatively, the cable  136  may be communicatively coupled by other processes, such as by using connectors at the end of the cable  136  and on the internal circuit board  138 . The internal circuit board  138  is supported by the pluggable body  130 . The circuit board  138  includes contact pads  140  at the mating end  132 . In  FIG. 1 , the mating end  132  is configured to be inserted into the module cavity  122  of the receptacle housing  108  and advanced in a mating direction along the mating axis  91 . In an exemplary embodiment, the pluggable body  130  provides heat transfer for the internal circuit board  138 , such as for the electronic components on the internal circuit board  138 . For example, the internal circuit board  138  is in thermal communication with the pluggable body  130  and the pluggable body  130  transfers heat from the internal circuit board  138 . In an exemplary embodiment, the heat is transferred from at or near the mating end  132 , such as where various electrical components are located on the internal circuit board  138 , to the cable end  134 . The heat is pulled out of the receptacle assembly  104  and mating end  132  and rejected to the external environment forward of the faceplate  109 . In other embodiments, the heat may be drawn into other portions of the pluggable body  130  and/or the heat may be directed to other portions of the pluggable body  130 , such as to the mating end  132  where the heat may be transferred to another heat sink or heat transferring component inside the chassis. 
     The receptacle assembly  104  includes a communication connector  142  having first and second mating interfaces  144 ,  146 . The first mating interface  144  is disposed within the module cavity  120 , and the second mating interface  146  is disposed within the module cavity  122 . The first and second mating interfaces  144 ,  146  are aligned with the port openings  121 ,  123 , respectively. Each of the first and second mating interfaces  144 ,  146  includes respective electrical contacts  145 ,  147  that are configured to directly engage the contact pads  140  of the pluggable module  106 . Thus, a single communication connector  142  may mate with two pluggable modules  106 . 
     In alternative embodiments, the receptacle assembly  104  does not include the stacked module cavities  120 ,  122  and, instead, includes only a single row of module cavities  120  or only a single module cavity  120 . In such embodiments, the communication connector  142  may have a single row of mating interfaces or a single mating interface. 
     The pluggable module  106  is an input/output (I/O) module configured to be inserted into and removed from the receptacle assembly  104 . In some embodiments, the pluggable module  106  is a small form-factor pluggable (SFP) transceiver or quad small form-factor pluggable (QSFP) transceiver. The pluggable module  106  may satisfy certain technical specifications for SFP or QSFP transceivers, such as Small-Form Factor (SFF)-8431. In some embodiments, the pluggable module  106  is configured to transmit data signals up to 2.5 gigabits per second (Gbps), up to 5.0 Gbps, up to 10.0 Gbps, or more. By way of example, the receptacle assembly  104  and the pluggable module  106  may be similar to the receptacle cages and transceivers, respectively, which are part of the SFP+ product family available from TE Connectivity. 
     Also shown in  FIG. 1 , the housing walls  114  of the receptacle housing  108  also form a separator plate  148  between the module cavities  120 ,  122 . The separator plate  148  extends generally parallel to the mating axis  91  between the front end  110  and the back end  112 . More specifically, the module cavity  120 , the separator plate  148 , and the module cavity  122  are stacked along the elevation axis  92 . Optionally, a light-indicator assembly (not shown), such as a light pipe may be provided in the separator cavity defined by the separator plate  148 . The separator cavity may allow airflow between the module cavities  120 ,  122  to enhance heat transfer from the pluggable modules  106  located in the module cavities  120 ,  122 . 
       FIG. 2  is a partially exploded view of the receptacle assembly  104  and illustrates the receptacle housing  108  and a plurality of the communication connectors  142  mounted to the circuit board  102 . In some embodiments, the receptacle housing  108  is formed from a plurality of interconnected panels or sheets. For example, the receptacle housing  108  includes a main panel or shell  170  that surrounds a housing cavity  172 , a plurality of interior panels  174 , a base panel  181 , and separator panels  176  defining the separator plate  148 . Each of the main panel  170 , the interior panels  174 , and the separator panels  176  may be stamped and formed from sheet metal. As described in greater detail below, each of the main panel  170 , the interior panels  174 , and the separator panels  176  may form one or more of the housing walls  114  that define the module cavity  120 , the module cavity  122 , and the separator plate  148  as shown in  FIG. 1 . As shown in  FIG. 2 , the main panel  170  includes an elevated wall  180 , sidewalls  182 ,  183 , and a back wall  184 . The elevated wall  180  is located furthest from the circuit board  102  when the receptacle assembly  104  is constructed. The base panel  181  may rest on the circuit board  102 . The sidewalls  182 ,  183  and the back wall  184  are configured to extend from the circuit board  102 , when mounted thereto, to the elevated wall  180 . 
     The interior panels  174  and the separator panels  176  are configured to be positioned within the housing cavity  172 . Within the main panel  170 , the interior panels  174  and the separator panels  176  apportion or divide the housing cavity  172  into the separate module cavities  120 ,  122  ( FIG. 1 ) and the separator cavity of the separator plate  148  ( FIG. 1 ). 
     In the illustrated embodiment, each of the interior panels  174  has a panel edge  191  that interfaces with the elevated wall  180  and a panel edge  192  that interfaces with the base panel  181  and/or the circuit board  102 . The panel edge  192  may include mounting pins or tails  194  that are configured to mechanically engage and electrically couple to vias or thru-holes  196  of the circuit board  102 . The panel edge  191  may include tabs or latches  197  that are configured to be inserted through slots  198  of the elevated wall  180  to couple to the elevated wall  180 . Likewise, the sidewalls  182 ,  183  and the back wall  184  may have panel edges  193  that include mounting pins or tails  195  configured to mechanically engage and electrically couple to corresponding vias  196  of the circuit board  102 . 
     The main panel  170 , the base panel  181 , the interior panels  174 , and the separator panels  176  may comprise conductive material, such as metal or plastic. When the receptacle housing  108  is mounted to the circuit board  102 , the receptacle housing  108  and the receptacle assembly  104  are electrically coupled to the circuit board  102  and, in particular, to ground planes (not shown) within the circuit board  102  to electrically ground the receptacle housing  108  and the receptacle assembly  104 . As such, the receptacle assembly  104  may reduce EMI leakage that may negatively affect electrical performance of the communication system  100  ( FIG. 1 ). 
       FIG. 3  is a perspective view of the pluggable module  106  in accordance with an exemplary embodiment.  FIG. 4  is a front view of the pluggable module  106  in accordance with an exemplary embodiment. The pluggable body  130  holds the internal circuit board  138  (shown in  FIG. 1 ). The pluggable body  130  has a first end  200  and an opposite second end  202  with sides  204 ,  206  extending between the first and second ends  200 ,  202 . The first and second ends  200 ,  202  and the sides  204 ,  206  extend lengthwise along a length  208  of the pluggable body  130  between the mating end  132  and cable end  134 . The first end  200 , second end  202  and sides  204 ,  206  define a cavity  210  (shown in  FIG. 1 ) that holds the internal circuit board  138 . Optionally, the internal circuit board  138  may be exposed at the mating end  132  for mating with the corresponding communication connector  142  (shown in  FIG. 2 ). 
     In an exemplary embodiment, the pluggable body  130  includes a first shell  212  and a second shell  214 . Optionally, the first shell  212  may define an upper shell and may be referred to hereinafter as upper shell  212 . The second shell  214  may define a lower shell and be referred to hereinafter as lower shell  214 . The upper shell  212  includes the first end  200 , which defines an upper end or top of the pluggable body  130 . The lower shell  214  includes the second end  202 , which may define a lower end or bottom of the pluggable body  130 . In an exemplary embodiment, the sides  204 ,  206  are defined by both the upper shell  212  and the lower shell  214 . However, in alternative embodiments, the upper shell  212  may define the sides  204 ,  206 , or alternatively, the lower shell  214  may define the sides  204 ,  206 . Optionally, the upper and lower shells  212 ,  214  may define approximately equal portions of the sides  204 ,  206 . Alternatively, either the upper shell  212  or the lower shell  214  may define a significant majority of the sides  204 ,  206 . 
     The internal circuit board  138  is arranged at or near a center plane of the pluggable module  106 , which may be centered between the first and second ends  200 ,  202 . Optionally, the upper and lower shells  212 ,  214  may meet at or near the center plane. A seam  218  may be defined at the interface between the upper and lower shells  212 ,  214 . 
     In an exemplary embodiment, the upper shell  212  is used for heat transfer from the internal circuit board  138 . The upper shell  212  is placed in thermal communication with the internal circuit board  138 . Heat generated by the internal circuit board  138  is drawn into the upper shell  212  and transferred therefrom. In an exemplary embodiment, the upper shell  212  includes a plurality of fins  220  extending therefrom. The fins  220  increase the surface area of the upper shell  212  and allow more efficient heat transfer from the upper shell  212 . The fins  220  may extend from any portion of the upper shell  212 . In various embodiments, the fins  220  extend from the top or first end  200 ; however the fins  220  may extend from the second end  202  and/or the sides  204 ,  206 . The fins  220  run lengthwise between the cable end  134  and the mating end  132 . Optionally, the fins  220  may run substantially the entire length from the cable end  134  to the mating end  132 . In the illustrated embodiment, the fins  220  are parallel plates. 
     The fins  220  are separated by channels  222 . Optionally, the channels  222  may have a uniform spacing between the fins  220 . For example, sides of the fins  220  may be planar and parallel. The fins  220  and channels  222  may extend along the length of the pluggable body  130  such that the channels  222  are open at the cable end  134  and/or the mating end  132  to allow air to flow along the fins  220 , such as from the cable end  134  toward the mating end  132  or from the mating end  132  toward the cable end  134 . In various embodiments, the channels  222  may be shaped or contoured, such as to encourage airflow therethrough. For example, the fins  220  may be shaped like an airfoil to increase airflow through the channels  222 . Optionally, the channels  222  may receive portions of a heatsink to encourage heat transfer from the pluggable body  130 . 
     In an exemplary embodiment, the upper shell  212  includes grid fins  224  extending across the channels  222  between adjacent fins  220 . The grid fins  224  are electrically conductive and electrically coupled to the fins  220 . The grid fins  224  reduce the size of the channels  222  to reduce EMI leakage through the channels  222 . For example, while it may be desirable to have large channels  222  to increase air movement across the fins  220 , such large channels  222  may be susceptible to EMI, which may degrade the signals transmitted by the pluggable module  106 . The grid fins  224  reduce the size of the channels  222  to block lower frequency EMI while still allowing a large amount of air flow through the channels  222 . In an exemplary embodiment, multiple grid fins  224  are provided in each channel  222  to reduce the size of the channels  222  by more than 50%. 
     The grid fins  224  divide the channels  222  into sub-channels  226 . For example, the sub-channels  226  may be defined both above and below each of the grid fins  224 . In an exemplary embodiment, the grid fins  224  are oriented perpendicular to the fins  220 . For example, the fins  220  may be oriented approximately vertically and the grid fins  224  may be oriented approximately horizontally. 
     Optionally, the grid fins  224  may be integral with the fins  220  and pluggable body  130 . For example, the upper shell  212  may be die cast, extruded, molded, or formed by other processes with the grid fins  224  integral and unitary with the fins  220 . Alternatively, the grid fins  224  may be separately manufactured and provided from the fins  220  and then coupled thereto. For example, the grid fins  224  may be soldered, welded, adhered, friction fit or otherwise mechanically and electrically coupled to the fins  220 . Optionally, the grid fins  224  may be thinner than the fins  220 . The fins  220  may be thicker for structural integrity, while the grid fins  224  may be thinner to allow as much air flow through the channels  222  as possible. 
     In an exemplary embodiment, the grid fins  224  do not extend the entire length of the fins  220 ; however in various embodiments the grid fins  224  may extend the entire length of the fins  220 . Optionally, the grid fins  224  may not be continuous along the length of the fins  220 . Alternatively, such dis-continuous grid fins  224  may tie the fins  220  together at regular intervals along the length of the fins  220 . Optionally, the tie points of the grid fins  224  may be staggered, as opposed to being aligned, as in the illustrated embodiment. For example, the grid fins  224  in one channel  222  may be at a different height as compared to the grid fins  224  in a different channel  222 . The area of the upper shell  212  that is most susceptible to EMI is at the opening in the receptacle assembly  104  and/or the faceplate  109  (both shown in  FIG. 1 ) because other portions of the upper shell  212  are surrounded by the receptacle housing, which provides some protection from EMI. As such, in an exemplary embodiment, the grid fins  224  are located proximate to exterior ends  228  of the fins  220 . The grid fins  224  may be positioned at a location along the fins  220  generally aligned with the exit point of the pluggable body  130  from the receptacle assembly. 
     The grid fins  224  extend between a front end  230  and a rear end  232 . Optionally, the grid fins  224  may be planar between the front and rear ends  230 ,  232  and extend generally parallel to the first end  200  of the pluggable body  130 . Alternatively, the grid fins  224  may be contoured and non-planar. The grid fins  224  may be angled inward toward the pluggable body  130  at the rear end  232 , which may direct the airflow in the associated sub-channel  226  inward toward the first end  200  to enhance cooling of the pluggable body  130 . Optionally, the grid fins  224  may have different lengths, such as with the upper-most grid fin being the longest and the lower-most grid fin being the shortest for directing airflow toward the first end  200 . The grid fins  224  may be airfoil shaped to encourage or increase airflow through the sub-channels  226 . The shapes of the grid fins may direct airflow in particular ways through the channels  222 . 
     Having the upper shell  212  comprise a plurality of the fins  220  allows more heat to be transferred by the upper shell  212  than with conventional pluggable body shells. The grid fins  224  control EMI through the channels  222 , allowing the channels  222  to be open at the cable end  134  for airflow into or out of the receptacle assembly through the channels  222 . Conventional pluggable body shells are typically solid at the cable end where the pluggable module interfaces with the receptacle assembly. A gasket is typically provided at the port opening to ensure the opening is sealed from EMI. Conventional pluggable body shells do not include channels or openings at the cable end. However, the upper shells  212  of the pluggable bodies  130  will provide improved heat transfer, as compared to conventional pluggable modules. More efficient heat transfer is achieved using the upper shell  212  with the fins  220  and channels  222  for airflow as compared to conventional shells of conventional pluggable bodies. 
     In an exemplary embodiment, the upper shell  212  is fabricated from a material having a high thermal conductivity. For example, the upper shell  212  may be manufactured from copper or aluminum. Using a material having a high thermal conductivity allows more efficient heat transfer from the internal circuit board  138 . In an exemplary embodiment, the upper shell  212  may be manufactured by an extrusion process such that the upper shell  212  includes an extruded body; however the upper shell may be manufactured by other processes in alternative embodiments, such as a die casting process, a machining process, a stamp and forming process of a sheet metal body, a layering build-up process, such as 3D printing, or another process. Extruding the upper shell  212  is a less expensive manufacturing process than some other processes, such as machining Additionally, extrusion is a process that may be used on materials having high thermal conductivity. For example, some other processes, such as die casting, require additives or impurities in some materials, such as aluminum, which lowers the thermal conductivity of such material. Additionally, the porosity of the material from die casting may be higher, leading to a lower thermal conductivity of the material. As such, shells made by such die casting may be less effective at heat transfer than shells made from extrusion. The extrusion process creates a simple structure having generally flat walls or surfaces. The fins  220  may be easily extruded with the other portions of the upper shell  212 . The upper shell  212  has a generally uniform cross-section along the length  208 , even including the fins  220 . The grid fins  224  may be extruded with the fins  220  or may be insert during a later assembly process. 
     The lower shell  214  may be manufactured in a similar manner as the upper shell  212 . The lower shell  214  may include fins (not shown). In contrast, in various embodiments, the lower shell  214  may be manufactured differently than the upper shell  212 . For example, substantially all of the heat from the internal circuit board  138  may be drawn into the upper shell  212  as opposed to the lower shell  214 . The upper shell  212  may thus be designed to achieve significant heat transfer. The lower shell  214 , in contrast, may be designed to achieve other advantages. For example, in various embodiments, because the upper shell  212  is extruded, such as to reduce cost of manufacturing the upper shell  212  and/or to provide a material having better heat transfer, the upper shell  212  may have a simple design, such as a substantially uniform cross-section. Because the upper shell  212  does not include robust assembly features, the lower shell  214  may have a more complex design as compared to the upper shell  212 . The complex design may require die casting or machining to form the various features needed. For example, the body of the lower shell  214  may have supporting features, alignment features, guide features and/or connection features for the internal circuit board  138  and/or for coupling the upper shell  212  to the lower shell  214 . For example, the body may include one or more pockets that receive various electrical components of the internal circuit board  138 . The body may include supporting elements for supporting the internal circuit board  138 . The body may include alignment elements for aligning the internal circuit board  138  within the cavity  210  and/or for aligning the upper shell  212  with the lower shell  214  for connection thereto. The body may include securing features used for securing the upper shell  212  to the lower shell  214 . For example, the securing features may include threaded bores that receive threaded fasteners to secure the upper shell  212  to the lower shell  214 . Other types of securing features may be provided in alternative embodiments, such as latches, clips, and the like for securing the upper shell  212  to the lower shell  214 . The body may include a cable support for supporting and/or aligning the cable  136  with the body. 
     The lower shell  214  may be manufactured from any type of material, such as a material that may be readily die cast. For example, the lower shell  214  may be manufactured from zinc, which is an easy metal to cast as zinc has high ductility, high impact strength and lower costs than other metals. 
       FIG. 5  is a front perspective view of the communication system  100  showing the pluggable modules  106  loaded in the receptacle assembly  104 . The receptacle assembly  104  passes through an opening in the faceplate  109  to a position rearward of the faceplate  109  such that the receptacle assembly  104  is interior of or inside the device having the faceplate  109 . In an exemplary embodiment, the faceplate  109  is conductive, such as a metal plate or bezel. The receptacle assembly  104  is electrically connected to the faceplate  109 , such as using one or more gaskets. The electrical connection at the interface between the faceplate  109  and the receptacle housing  108  reduces EMI at the interface. 
     In an exemplary embodiment, the fins  220  extend to the cable ends  134  of the pluggable bodies  130  such that the channels  222  are open to the external environment forward of the faceplate  109 . The fins  220  are positioned along the pluggable body  130  such that the fins  220  are exposed at the port openings  121 ,  123  of the receptacle assembly  104 . The fins  220  may extend from inside the receptacle assembly  104  to outside of the receptacle assembly  104 , such as beyond the front end  110 . The fins  220  may extend beyond or forward of the faceplate  109  in various embodiments. Having the fins  220  extend to the cable ends  134  allows the channels  222  to facilitate airflow between the internal environment and the external environment of the device having the faceplate  109 . For example, air is able to flow through the channels  222  from inside the receptacle assembly  104 , and is exhausted forward of the faceplate  109 , which cools the fins  220  and the pluggable body  130 . Alternatively, cool air is able to flow from outside of the receptacle assembly  104  through the channels  222  into the receptacle assembly  104  to cool the fins  220  and the pluggable body  130 . 
     The grid fins  224  may be provided at the cable ends  134  of the pluggable bodies  130 , such as at the front ends of the fins  220 . The grid fins  224  are positioned along the fins  220  such that the grid fins  224  are aligned with the receptacle housing  108  at the port openings  121 ,  123  of the receptacle assembly  104 . The grid fins  224  may extend from inside the receptacle assembly  104  to outside of the receptacle assembly  104 , such as beyond the front end  110 . The grid fins may extend from exterior portions of the fins  220 , which are located exterior of the receptacle assembly  104 , to interior portions of the fins  220 , which are located interior of the receptacle assembly  104 . The grid fins  224  may extend beyond or forward of the faceplate  109  in various embodiments. Having the grid fins  224  aligned with the faceplate  109  and the front end  110  provides EMI protection through the port openings  121 ,  123  to reduce EMI leakage into and out of the receptacle housing  108 . Air is able to flow through the channels  222  with little restriction from the grid fins  224 . 
       FIG. 6  is a front perspective view of the communication system  100  showing the pluggable modules  106  in accordance with an exemplary embodiment loaded in the receptacle assembly  104 . The housing walls of the receptacle housing are not shown in  FIG. 6  for clarity to show the pluggable modules  106  mated with the communication connector  142 . The receptacle assembly  104  is provided without the separator plates  148  (shown in  FIG. 1 ). Rather, the lower pluggable module  106  has taller fins  220  extending into the space otherwise used by the separator plates  148  to transfer more heat. The upper pluggable module  106  also has taller fins  220  and the housing walls of the receptacle housing may accommodate the taller fins  220 . The pluggable modules  106  have additional grid fins  224  to accommodate the taller channels  222 . 
     Optionally, the upper pluggable module  106  may rest on the lower pluggable module  106 . Heat may be transferred from the lower pluggable module into the upper pluggable module  106  at the locations where the fins  220  of the lower pluggable module  106  engage the upper pluggable module  106 . 
     The grid fins  224  are aligned with the faceplate  109 . The grid fins  224  extend from outside of the receptacle assembly  104  to inside of the receptacle assembly  104 . The grid fins  224  reduce EMI leakage into and/or out of the receptacle assembly  104 . 
     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. 
     As used in the description, the phrase “in an exemplary embodiment” and the like means that the described embodiment is just one example. The phrase is not intended to limit the inventive subject matter to that embodiment. Other embodiments of the inventive subject matter may not include the recited feature or structure. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.