Abstract:
Electronic module, such as a small footprint pluggable (SFP) connector module, including a housing, an electroconductive cage for shielding the module and a latch for the cage to the housing. The latch includes a separate latch member accommodated between the housing and the cage, and at least one resiliently protruding tip. The cage is provided with an opening for receiving the resiliently protruding tip.

Description:
FIELD OF THE INVENTION 
     The present invention relates to electronic or optoelectronic modules, such as pluggable transceiver modules for high speed fiber optical communications and pluggable electronic modules shielded by a cage fixated by a latch mechanism. 
     BACKGROUND OF THE INVENTION 
     Electronic modules, such as optoelectronic transceivers, are available which can be plugged on a printed circuit board (PCB). Particular examples are so-called Small Form-Factor Pluggable (SFP) transceivers, such as SFP&#39;s of the small cubic form factor (SCFF) type. Such transceivers are typically mounted on a PCB and can be shielded against electromagnetic interference by a cage of an electro-conductive material. Such a cage can be mounted onto the housing of the electronic module using a latch mechanism. 
     There is a need for a module having an easily accessible latch mechanism for a releasable coupling of the module within the cage. The latch mechanism should be easy to manufacture, assemble and operate and show a low failure rate with repetitive use. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention a module is provided according to claim  1 . Such a separate latch member can be manufactured against low costs and can form a very effective latch for coupling the module to the cage in a releasable manner. 
     In a module according to claim  2  or  3  the latch member is particularly stably held between the housing and the cage. 
     In a module according to claim  3  the upper face of the cage can be kept free, e.g., for use of one or more additional spring leaf ground contacts or tabs. 
     The latch member may be particularly easy and inexpensive to manufacture. The strip can efficiently be made, e.g., by punching and  subsequent bending sheet material. The latch member can for instance be L-shaped, having only one bent resilient end, or it can be U-shaped, having two opposite resilient bent ends. 
     In an example module the twisted tips are more easily accessible for a user via the respective openings in the cage. By twisting the tips, one lateral side edge will protrude further away from the housing than the opposite lateral side edge of the tip. If the tip is twisted such that the lateral side edge directed to the open side of the cage is twisted outwardly it will more effectively lock the housing  within the cage. 
     In a further aspect a module is provided, enabling another effective snap fit between the housing and the cage using a member which can be manufactured against low costs. Such a member can advantageously be made wherein the latch member is kept in place in the cavity in housing with a tight fit. 
     In an example module the metal latch member shields the opening in the cage, so the shielding by the cage is riot significantly interrupted by the openings. 
     The electronic module according to the invention is particularly useful as, e.g., a connector module, such as a small form factor pluggable (SFP) connector, e.g., SFP&#39;s of the small cubic form factor (SCFF) type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be elucidated with reference to the figures wherein: 
         FIG. 1 : shows in perspective view an embodiment of an electronic module according to the invention; 
         FIG. 2 : shows a housing for the module of  FIG. 1 ; 
         FIG. 3 : shows a spring for a latch of the module of  FIG. 1 ; 
         FIG. 4 : shows in perspective cross section a further embodiment of an electronic module according to the invention; 
         FIG. 5 : shows a perspective view of a housing of  FIG. 4 ; 
         FIG. 6 : shows in perspective view a latch member of the module of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  shows connector module  1  forming an optoelectronic transceiver of the small cubic form factor (SCFF) type. The module  1  comprises a housing  2  shielded by a cage  3  of an electro-conductive sheet metal. The housing  2  is shown separately in  FIG. 2  and comprises a rear end  4  with a number of pin contacts  5  and a front end  6  with a cavity  7  giving access to an optical port (not shown). The rear end  4  is shielded by a metal cover  8 . 
     The cage  3  comprises a metal base plate  9  with two opposite upright side edges  10  and an upright rear edge  11 . Clamped between the two side edges  10  is a top portion  12  of the cage  3  having two side walls  13 , a top wall  14 , a front wall (not shown) and an open end  15 . At the open front end  15 , the side walls have a corner  16  chamfered by an inwardly curved edge  17 . The side edges  10  of the base plate  2  are provided with inwardly bent lips  18  for clamping the lower edge of the top portion  12 . The top portion  12  is provided with inwardly bent lips  19  for contacting the housing  2  to form ground contacts. 
     The housing  2  is inserted into the cage  3  with the rear end  4  abutting the rear wall of the cage  3 . The rear wall leaves an opening (not shown) for the pin contacts  5 . The upper edge of the front end.  6  of the housing  2  is chamfered in a way corresponding to the corners  16  of the side walls  13  of the cage  3 . 
     A latch  20  holds the housing  2  within the cage  3 . The latch  20  comprises a latch member  21 , shown in  FIG. 3 . The latch member  21  comprises a metal strip  22  with two ends  23 ,  24  bent under an angle of more than 90 degrees. The two ends  23 ,  24  are linked by a middle section  25  spanning a distance corresponding to the width of the housing  2 . The two ends  23 ,  24  have a terminal tip  26  which is bent backwards and twisted. Near the open end  15  the side wails  13  of the cage  3  have an opening  27  for receiving one of the terminal tips  26  of the latch member  21 . At its lower side the housing  2  comprises a recess  28  extending over the full width of the housing  2 . The recess  28  serves to accommodate the middle section  25  of the strip  22  in such a way that the middle section  25  is flush with the adjacent surface of the housing  2 . 
     The terminal tips  26  are twisted in such a way that the side  29  directed to the open end  15  projects further away from the housing  2  than the oppositely directed flatter side  30 . When the housing  2  is slid into the cage  3 , the flatter side  30  will first contact the cage  3  and the terminal tip  26  will be pushed inwardly until it reaches the opening  27 . After the terminal tip  26  snaps into the opening  27  and the most protruding side  29  of the tip  26  blocks any outward movement of the housing  2  from the care  3 . The housing  2  can only be released from the cage  3  by pressing the tip  26  inwardly. 
       FIG. 4  shows an alternative embodiment of a module according to the invention, which is similar to the module  1  of  FIG. 1 , but which is provided with a different latch  40 , which is shown in more detail in  FIG. 6 . Same parts are indicated with the same reference numbers as in  FIGS. 1 and 2 . The latch  40  is a sheet metal latch member comprising a square flat body  41  with a laterally extending resilient cantilevered finger  42 . The resilient finger  42  carries a triangular upwardly protruding resilient tip  43 . The housing  2  is provided with a cavity  44  for accommodating the body  41  in a manner that the body  41  is sunk within the cavity  44  and its upper edge  45  is flush with the adjacent surface of the housing  2 . The cavity  44  is extended to allow inward movement of the resilient finger  42  under the action of a pressure force to such extent that the triangular resilient tip  43  is within the cavity  44 . 
     The flat body  41  of the latch member is profiled to have an offset central section  46  extending from the upper edge  45  to a point  47  at a distance before the opposite edge  48 . As shown in  FIG. 5  the cavity  44  is correspondingly shaped with an offset middle section  49  to form a tight fit with the latch member  40  when the body  41  is inserted within the cavity  44 . 
     The cage  3  is provided with an opening  50  for receiving the triangular resilient tip  43 . During assembly of the electronic module  1 , the latch member  40  is inserted into the cavity  44  and held by the cavity  44  in a clamping manner. In this position, the triangular resilient tip  43  protrudes from the surface of the housing  2 . During insertion of the housing  2  into the cage  3 , the tip  43  is pushed into the activity  44 . When the opening  50  in the cage  3  is slid over the position of the loaded resilient tip  43 , the tip  43  pops up to snap into the opening  50  and to fixate the relative position of the housing  2  and the cage  3 . The housing  2  can be removed from the cage  3  by pushing down the resilient tip  43  into the cavity  44 . The housing  2  can now be slid out of the cage  3 .