Patent Publication Number: US-6666720-B1

Title: Electrical connector receptacle with module kickout mechanism

Description:
RELATED APPLICATIONS 
     This application is related to Application Ser No. 10/208,921, filed on the same date as the present application, titled “Electrical Connector Receptacle Cage With Interlocking Upper and Lower Shells”, the complete subject matter of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Certain embodiments of the present invention generally relate to electrical cable assemblies for use with high speed serial data, and more particularly, to electrical connector receptacles for connecting to a circuit board and receiving a plug or small form-factor pluggable module. 
     In the past, electrical connector receptacles have been proposed for receiving a plug or module which then connects to a circuit board. Conventional connector receptacles have been comprised of one or two pieces. For two piece receptacles, the bottom piece is soldered to the circuit board using multiple solder pins. The top piece is then mounted on and may also be soldered to the bottom piece. The top and bottom pieces define an internal space into which the module is inserted. The module is held in place by a mechanical locking mechanism, such as a protrusion from the module, projecting into a hole in the bottom piece. 
     In order to remove the module from the receptacle, an ejection button on the module is pushed in towards the back of the receptacle to disengage the locking mechanism. Conventional receptacles contain “kickout” springs typically located at the rear of the receptacle which apply a force against the module. When the locking mechanism is disengaged, the force induced on the module by the kickout spring is intended to assist in the removal of the module from the receptacle. For example, in the past, short, narrow kickout springs have been formed integral with the sides of the receptacle and bent to project towards the opening in the front of the receptacle. Alternatively, the kickout springs have been formed integral with the sides and bent into the interior of the receptacle in an “S” shape, wherein one curve of the S engages the module and one curve engages the back wall of the receptacle. The aforementioned kickout springs are typically aligned horizontally, or parallel to the floor of the receptacle and provide a double spring action as one spring is formed integral with each side. 
     However, conventional kickout spring designs often are unable to provide a sufficient force to overcome the friction and mating force of the ground contacts electrically engaging the module and receptacle. Additionally, some conventional kickout spring designs have a very short working range, thereby further limiting the effectiveness of the kickout springs. As a result, the user must push in, and hold, the ejection button on the module while simultaneously pulling the module out of the receptacle. The effort to hold in the ejection button and simultaneously pull on the module is awkward and time consuming, and may require a user to use both hands and/or two separate tools to remove the module. 
     A need exists for an electrical connector receptacle that improves the kickout effectiveness of the receptacle without sacrificing electrical performance or the latching abilities of the receptacle. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth below. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with at least one embodiment, a small form factor pluggable (SFP) cage is provided including upper and lower shells. At least one of the upper and lower shells includes pins configured to be press fit onto a circuit board. The upper and lower shells are joined to one another to define a module retention chamber with an open front end configured to accept an SFP module. At least one of the shells has a rear wall closing the back end of the module retention chamber, and side walls extending between the front and back ends. The upper shell has a top wall extending between the front and back ends which has a flexible section formed proximate the back end. A kickout spring is joined to the flexible section of the top wall and has a module engaging section extending into the module retention chamber toward the front end. The kickout spring and flexible section are configured to contact and exert an ejection force on the SFP module when the module is inserted into the module retention chamber. 
     In an alternative embodiment, an electrical connector receptacle cage is provided including upper and lower shells joined together to form a plug retention chamber configured to accept an electrical plug through an open front end. At least one of the upper and lower shells has a rear wall closing the back end and having side walls extending between the front and back ends. The upper shell includes a top wall with a flexible section formed proximate the back end. The flexible section of the top wall is physically separated from the side and rear walls. A kickout spring is joined to the flexible section of the top wall. The kickout spring has a plug engaging section extending into the plug retention chamber toward the front end. The plug engaging section contacts and exerts an ejection force onto the plug when inserted into the plug retention chamber. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 illustrates an upper shell of a small form-factor (SFP) cage formed of a single piece of sheet material formed in accordance with an embodiment of the present invention. 
     FIG. 2 illustrates a bottom view of the upper shell formed in accordance with an embodiment of the present invention. 
     FIG. 3 illustrates a lower shell of an SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 4 illustrates an assembled SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 5 illustrates a side view of the kickout spring and a portion of the SFP cage with an SFP module inserted formed in accordance with an embodiment of the present invention. 
     FIG. 6 illustrates a top view of a module inserted into an assembled SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 7 illustrates a bottom view of a module inserted into an assembled SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 8 illustrates the interlocking features of an upper shell of an SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 9 illustrates the interlocking features of a lower shell of an SFP cage formed in accordance with an embodiment of the present invention. 
     FIG. 10 illustrates an assembled SFP cage utilizing the interlocking features of FIGS. 8 and 9 formed in accordance with an embodiment of the present invention. 
    
    
     The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the preferred embodiments of the present invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates an upper shell  102  of a small form-factor (SFP) cage  100 . The upper shell  102  is formed of a single piece of sheet material. The upper shell  102  includes a top wall  114  and two side walls  110 . The sheet material is bent along edges  124  between the top wall  114  and the side walls  110 . Base portions  126  are bent inward toward one another and up toward the top wall  114 , and may be parallel to the top wall  114 . The base portions  126  are formed on the bottom edge  125  of the side walls  110  proximate an open front end  112  formed by the front edges of the top wall  114 , side walls  110  and base portions  126 . 
     Press fit pins  104  are stamped and formed integral along the bottom edge  125  of the side walls  110 . The press fit pins  104  occupy substantially the same plane as the side walls. The press fit pins  104  are formed with an elongated, or oblong shaped, body with an elongated hole in the interior portion, and further comprise shoulders  105  integral with bottom edge  125  which extend out from each side of the press fit pins  104 . The press fit pins  104  are snappingly received by, and securely fasten the SFP cage  100  to, a circuit board (not shown). The shoulders  105  rest on the surface of the circuit board, acting as a standoff between the SFP cage  100  and the circuit board. 
     Electromagnetic interference (EMI) pins  134  are stamped and formed integral along the bottom edge  125  of the side walls  110 . The EMI pins  134  may be shorter in length than the press fit pins  104  and are substantially rectangular in shape with a rounded tip. The EMI pins  134  are inserted through holes in the circuit board to penetrate the electrical plane of the circuit board. The EMI pins  134  may or may not contact the circuit board, or may be electrically connected to the circuit board. Alternatively, EMI pins  135  (FIG. 4) may be formed as press fit pins, providing improved mechanical connection between the SFP cage  100  and the circuit board. The EMI pins  135  of FIG. 4 may be narrower in width and the same length as the press fit pins  104 . The EMI pins  135  of FIG. 4 may also be wider and longer than the EMI pins  134  illustrated in FIG.  1 . Alternatively, press fit pins  104  and/or EMI pins  134 ,  135  may be formed as solder pins and soldered to the circuit board to form the mechanical and electrical connection therewith. By forming the press fit pins  104  and EMI pins  134 ,  135  integral with and substantially parallel to the side walls  110  of the upper shell  102 , the force applied to the upper shell  102  when mounting the SFP cage  100  on the circuit board does not cause the upper shell  102  or lower shell  148  to deflect, nor deform in shape. 
     Ground members  130  are stamped and formed proximate the open front end  112  on the front region of the top wall  114 , the side walls  110 , and the base portions  126 . The ground members  130  are biased outward from the top wall  114 , side walls  110 , and base portions  126  to engage a chassis, bezel, or other grounding structure through which the SFP cage  100  may be inserted. By bending the ground members  130  outward, open windows  133  and tabs  129  are formed in the upper shell  102 . The base portions  126  further include a rear portion  127 . When the ground members  130  on the base portions  126  are deflected upward by the chassis, the lead edge  131  of the ground member  130  may engage the tab  129 . Similarly, tabs  129  on the top wall  114  and side walls  110  may engage corresponding ground members  130  when the SFP cage  100  is mounted in the chassis. 
     Ventilation holes  132  are stamped out of the top wall  114 . Latching features  128  are stamped in side walls  110 . The latching features  128  project outward to form a slightly ramped surface with a lance at the top edge. The rear end  115  of the top wall  114  has a pair of inner notches  117  and a pair of outer notches  118  cut therein to define a pair of tabs  138 . The tabs  138  may be used to attach the upper shell  102  to a carrier strip during manufacture. The tabs  138  extend toward the rear end  106  of the upper shell  102 . Inner notches  117  and outer notches  118  may be parallel to one another. The outer notches  118  define therebetween a flexible portion  116  that cooperates with a kickout spring  136  (FIG. 2) to eject a module. 
     The back ends  113  of the side walls  110  are bent in towards one another to close the rear end  106  of the upper shell  102 . The back ends  113  overlap and form a rear wall  108 , enclosing rear end  106 . The rear wall  108  is perpendicular to the side walls  110 . A portion of a back end  113  is bent inward toward the front end  112  and again away from the front end  112  to form a ridge  109  and an inner portion  111  of the rear wall  108 . By forming the rear wall  108  integral with the sides  110  as illustrated, the rear wall  108  may flex outward when a force perpendicular to the rear wall  108  is exerted on rear wall  108 . Additionally, by forming rear wall  108  integral with the sides  110 , the upper shell  102  is strengthened and more robust, thus unlikely to deform when force is applied to the top wall  114  of the SFP cage  100  when mounting the SFP cage  100  on the circuit board. 
     FIG. 2 illustrates a bottom view of the upper shell  102 . The rear end  115  of the top wall  114  is bent down at an acute angle into the module retention chamber  200  of the upper shell  102  to form kickout spring  136 . Kickout spring  136  has a spring width L 1  extending between the inner notches  117  which is slightly less than the shell width L 2  between the side walls  110 . The kickout spring  136  includes a lead edge  137  positioned within the module retention chamber  200  remote from the rear wall  108 . C 2  illustrates the center line of the upper shell relative to the side walls  110 . L 3  illustrates the distance from the center line C 2  to the side wall  110 . L 3  is substantially equidistant from the center line C 2  to each of the side walls  110  along the length of the upper shell  102 . Although the kickout spring  136  is illustrated as integral with the top wall  114  of the upper shell  102 , it should be understood that the kickout spring  136  may also be utilized with other SFP cages, such as a one piece SFP cage. 
     FIG. 3 illustrates a lower shell  148  of the SFP cage  100 . The lower shell  148  is bent and formed from one piece of sheet material. Snap over tabs  150  are bent to extend perpendicular to a bottom wall  152 . The snap over tabs  150  include an opening  153  and a leading edge  149  at the top end. The leading edge  149  is bent slightly outward at intersection  151 . A spring latch  154  and interlocking members  158  protrude from the front edge of the bottom wall  152  to snappably engage a module inserted into the cage  100 . The interlocking members  158  comprise a base section  167  and a tip portion  168 . The tip portion  168  protrudes from the front end of the base section  167  at the intersection  169  and is narrower in width than the base section  167 . The tip portion  168  is bent downward at the intersection  169 . 
     Grooves  156  are cut in the front edge of the bottom wall  152  to separate the spring latch  154  from the interlocking members  158  which are located on either side of the spring latch  154 . The spring latch  154  is bent downward and back to form a plateau  161 . The plateau  161  occupies a plane parallel to and slightly below the plane of the bottom wall  152  relative to the module retention chamber  200  formed when the upper and lower shells  102  and  148  are joined. Forward of the plateau  161 , the spring latch  154  is bent up in the direction of arrow A to form an intermediate portion  162  with a triangular shaped cutout  164 . Forward of the triangular shaped cutout  164 , the spring latch  154  is bent downward at an obtuse angle to the intermediate portion  162  to form a guiding lip  166 . 
     Notches  155  are cut from the outer edges  163  of the bottom wall  152  towards the center line C 1  of lower shell  148 . The locations of the notches  155  coincide with the placement of the press fit pins  104  on the upper shell  102 . Protrusions  157  extend from the outer edges  163  at other positions, away from the center line C 1 . The distance L 4  from the center line C 1  of the lower shell  148  to the protrusions  157  is greater than the distance L 3 , which is the distance between the side walls  110  and center line C 2  of the upper shell  102  (FIG.  2 ). Therefore, the protrusions  157  may contact and/or extend beyond the bottom edge of side walls  110 . In contrast, the distance L 5  from the center line C 1  of the lower shell  148  to the notches  155  is less than or equal to the distance L 3 . Thus, the notches  155  may contact the side walls  110  or the press fit pins  104 . Protrusions  159  proximate the front of bottom wall  152  are a distance L 6  from the center line C 1 . The distance L 6  is less than or equal to L 3 , allowing the bottom wall  152  at protrusions  159  to fit between the side walls  110 . Protrusions  159  may contact the side walls  110 . 
     Two crescent shaped grounding beams  160  protrude from the rear end  149  of the bottom wall  152 . A third crescent shaped grounding beam  160  is bent and formed in the central region of the bottom wall  152  behind the spring latch  154 . The crescent shaped grounding beams  160  are also illustrated in FIG. 7, which includes a bottom view of the lower shell  148 . The grounding beams  160  are integral with the bottom wall  152 , and are bent downward and occupy a plane perpendicular to the plane of the bottom wall  152 . The grounding beams  160  protruding from the rear end  149  are oriented such that the grounding beams  160  curve away from each other. The grounding beams  160  are inserted into holes in the circuit board to form a grounding connection therewith. The grounding beams  160  may be inserted into the circuit board with less force than the force used to insert press fit pins  104  on upper shell  102 . Thus, the lower shell  148  does not deflect when the SFP cage  100  is press fit onto the circuit board. 
     FIG. 4 illustrates an assembled SFP cage  100 . The upper shell  102  and lower shell  148  are mated together to form the module retention chamber  200  which is accessible through the open front end  112 . As discussed previously, the EMI pins  135  may be press fit pins. Alternatively, the press fit pins  104  and EMI pins  135  may be formed as solder legs, and thus may be soldered to the circuit board. 
     During assembly, the spring latch  154  on the lower shell  148  is inserted along the path of arrow B into the interior of the upper shell  102  at an acute angle relative to the base portions  126  such that the interlocking members  158  are positioned above the base portions  126 , and the spring latch  154  is located between the base portions  126 . The press fit pins  104  on the upper shell  102  are positioned interleaved with the snap over tabs  150  on the lower shell  148 . The lower shell  148  is then rotated along the path of arrow C in order that the snap over tabs  150  slide along the outside of the upper shell  102  until the snap over tabs  150  engage the latching features  128  on the side walls  110 . Therefore, the SFP cage  100  may be assembled without soldering, welding, or other fastening mechanism or process. 
     The base sections  167  of the interlocking members  158  engage the rear portions  127  of the base portions  126  (FIG. 1) with a downward force. The base sections  167  extend to at least the forward edge of the tab  129  (FIG. 1) on the base portions  126 . The tip portion  168  of the interlocking members  158  extends over the tab  129  of the base portions  126  and extends downward into the window  133  formed when the grounding members  130  are stamped. Therefore, when the SFP cage  100  is mounted in a chassis or bezel, and the ground members  130  are engaging the chassis, the downward force of the interlocking members  158  of the lower shell  148  on the base portions  126  of the upper shell  102  prevents the base portions  126  from deflecting upward into the module retention chamber  200 , and the tip portion  168  engages the inner edges of the window  133 , preventing the side walls  110  from being deformed inward. 
     FIG. 8 illustrates an alternative embodiment of the interlocking features of upper shell  210 . Features previously discussed are illustrated in FIGS. 8-10 using the aforementioned item numbers. Upper shell  210  includes base portions  212  formed integral with side walls  214 . Base portions  212  include a notch or shear  216  cut in the back end of base portions  212 . An upper tab  218  is bent and formed integral with base portions  212  and adjacent to the shear  216 . Upper tab  218  is bent toward top wall  220  to form a ramped surface  222 . Upper tab  218  is then bent away from top wall  220  to form a plateau  224  substantially parallel to base portions  212 . Back end  226  is adjacent to the shear  216  and occupies the same plane as the base portions  212 . 
     FIG. 9 illustrates an alternative embodiment of the interlocking features of lower shell  230 . The bottom wall  231  includes a notch or shear  232  cut in the front edge. Lower tab  234  is integral with bottom wall  231  and is bent and formed adjacent to the shear  232 . Lower tab  234  is bent downward to form ramped surface  236 , then bent upwards to form a plateau  237  substantially parallel to bottom wall  231 . Front portion  238  is adjacent to the shear  232  and occupies the same plane as bottom wall  231 . 
     FIG. 10 illustrates an assembled SFP cage  240  utilizing the interlocking features of upper shell  210  and lower shell  230 . Upper shell  210  and lower shell  230  are mated together in a manner similar to SFP cage  100  of FIG. 4, forming a front opening  242 . However, the plateau  224  of upper tab  218  extends over, touches and may press upon the plateau  237  of lower tab  234 , and front portion  238  extends partially over, touches and may press upon a portion of the back end  226 . Therefore, upper and lower tabs  218  and  234 , combined with front portion  238  and back end  226 , prevent the front opening  242  from being deformed from side, top, and/or bottom forces when the SFP cage  240  is mounted in a chassis or bezel. As illustrated in FIGS. 8 and 9, the interlocking features may be symmetrical, wherein upper and lower tabs  218  and  234  are formed on each side of the upper and lower shells  210  and  230  in the same orientation from left to right. Alternatively, as illustrated in FIG. 10, the interlocking features may be asymmetrical, wherein upper and lower tabs  218  and  234  are both formed closer to the side walls  214 , or closer to the center of SFP cage  240 . 
     FIG. 5 illustrates a side view of the kickout spring  136  and a portion of the SFP cage  100  with an SFP module  140  inserted. The kickout spring  136  comprises a module engaging portion  170  integral with a lever portion  171  that projects downward and into the module retention chamber  200  to engage a plug or SFP module  140  at lead edge  131 . The kickout spring  136  also includes a radiused portion  172 . The radiused portion  172  is integral with the flexible section  116  proximate the back end of the top wall  114 , and may not engage rear wall  108  when kickout spring  136  is at rest. When no force is applied to the kickout spring  136 , the lever portion  171  rests at an acute angle X relative to the rear wall  108 . Also, kickout spring  136  occupies a space proximate the rear wall  108  with the lead edge  131  located a distance D 2  from the rear wall  108 , such that a module  140  cannot be locked into the SFP cage  100  without deflecting the kickout spring  136 . Alternatively, kickout spring  136  may extend beyond lead edge  131 . Kickout spring  136  may be bent downward and toward rear wall  108  to form rear wall engaging portion  173 . The outer end  175  of the rear wall engaging portion  173  may be rounded slightly. 
     FIGS. 6 and 7 illustrate top and bottom views, respectively, of a module  140  inserted into an assembled SFP cage  100 . FIGS. 5-7 will be discussed together.  1391  When the module  140  is inserted into the module retention chamber  200  in the direction of arrow D, the back wall  141  of the module  140  engages the lead edge  131  of the module engaging portion  170  of the kickout spring  136 . As the insertion force from the module  140  in the direction of arrow D overcomes the spring force in the direction of arrow E created by the kickout spring  136 , the kickout spring  136  deflects in the arcuate direction of arrow F towards the rear and top walls  108  and  114 . For example, the module engaging portion  170  may be deflected a distance D 1  as measured from the position of the lead edge  131  when in its resting position. As the kickout spring  136  deflects, the radiused portion  172  flexes up and back, and may contact and deflect the rear wall  108  outward. As a result, the angle X becomes smaller. Also, the flexible section  116  of the top wall  114  between outer notches  118  bends upward and away from the plane of the top wall  114  in the direction of arrow G. The resiliency and memory of the flexible section  116  is enhanced by the length L 1  of the kickout spring  136 . Optionally, if kickout spring  136  includes the rear wall engaging portion  173 , the outer end  175  may contact and deflect rear wall  108  outward with a force in the direction of arrow D. 
     The module  140  is pushed in the direction of arrow D until the module latch  174  (FIG. 7) slides under the guiding lip  166  on the spring latch  154  and engages the cutout  164 . When securely latched, the release button  176  of the module  140  is fully extended towards the front end of the module  140  and fits under the guiding lip  166  of the spring latch  154 . The module latch  174  and cutout  164  securely hold the module  140  and SFP cage  100  mated together while the module engaging portion  170  exerts a potential force on the back wall  141  of the module  140 . It should be understood that other latching mechanisms may be used to secure the module  140  inside SFP cage  100 . 
     To unlatch the module  140  from the SFP cage  100 , the release button  176  is pressed towards the rear wall  108  of SFP cage  100 , in the direction of arrow D. The release button  176  slides under the spring latch  154  and deflects the spring latch  154  out and away from bottom wall  152  until the module latch  174  is no longer engaged by the cutout  164 . The flexible section  116  exerts a force in direction H, the rear wall  108 , module engaging portion  170  and lever portion  171  exert force in the direction E. The directions E and H and the force exerted may vary depending upon the length of the kickout spring  136 , the angle X, the sheet material used to construct the upper shell  102 , and the like. The module  140  is ejected at least the distance D 1  out of the SFP cage  100  by the forces, and the kickout spring  136  returns to its original location at angle X relative to the rear wall  108 . 
     The force of the kickout spring  136  combined with the forces from the flexible section  116  and rear wall  108  provides sufficient, reliable force to eject the module  140 . Furthermore, the kickout spring  136  is larger than previous kickout springs as discussed previously, and thus is better able to retain its memory and resiliency when modules  140  are inserted and ejected multiple times. 
     The SFP cage  100  provides improved strength and rigidity. The ground members  130  are located on the upper shell  102  which defines the open front end  112 . The interlocking features of the upper and lower shells  102  and  148 , such the base portions  126 , base sections  167  and tip portions  168  (FIGS.  1 - 4 ), and upper and lower tabs  218  and  234 , front portions  238  and back ends  226  (FIGS.  8 - 10 ), prevent the open front end  112  from being deformed when mounting the SFP cage  100  on a circuit board and/or in a chassis or bezel. By locating the press fit pins  104  and EMI pins  134 ,  135  integral with and parallel to the side walls  110  of the upper shell  102  rather than on the lower shell  148  of the SFP cage  100  or on a single piece SFP cage, the side walls  110  are not deformed when the SFP cage  100  is press fit on a circuit board. Furthermore, by forming the closed back end  106  integral with and perpendicular to the side walls  110 , increased rigidity of the upper shell  102  is achieved. 
     While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. 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. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.