Abstract:
A connector with a transceiver and a socket on a substrate receiving the transceiver. The transceiver is movable within the socket into a locked position in a direction parallel to the substrate. The socket and transceiver include complementary locking sections cooperating when the transceiver is in the locked position. During the movement the transceiver wipes over contacts, e.g., on the substrate or on an interposer.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The invention relates to a connector comprising an assembly of a transceiver and a socket interconnecting the transceiver with circuitry on a substrate, such as a printed circuit board. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    In optical communication systems optical fiber cables are typically coupled to an opto-electronic transceiver which is in turn coupled to a substrate, such as a circuit board. Such a transceiver typically includes a housing with opto-electronic elements, an array of contacts to be coupled to associated contacts on the substrate, and an optical contact unit configured to connect to a complementary optical cable connector. 
         [0003]    Such transceivers can be coupled to a substrate by means of a socket holding the transceiver. In some cases the socket may comprise an interposer, which is a board with a lower side presenting an array of contacts, typically a ball grid array (BGA), to be connected to contacts on the substrate, and a top side similarly provided with an array of contacts, generally of a different type, to be connected to contacts at the lower side of the transceiver. To obtain high quality signal transfer, the contacts should be clean and the pressure on the contacts by the transceiver should be substantially equal for all contacts. 
         [0004]    In the transceiver heat is generated which should be dissipated as much as possible in order to prevent failure. For that reason it is desirable to maximize outer surface area of the transceiver module. 
         [0005]    The transceiver in such an LGA configuration should preferably be held in the socket in a releasable manner, e.g., to enable replacement of the transceiver in case of failure. To this end release mechanisms can be used, but such release mechanism typically require finger space for accessibility and actuation by a user. This limits the maximum number of sockets which could be placed per unit area. Moreover, the release mechanisms typically interrupt top and/or side faces of the board connector, thereby reducing heat dissipation surface. 
         [0006]    It is an object of the invention to provide a system for connecting a transceiver to a socket reducing the risk of signal transfer failures due to contamination of the contacts or due to uneven contacting pressure. It is a further object to provide a releasable connection without requiring extra space for manual actuation. It is a further object to provide a release mechanism leaving a larger area for heat dissipation. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    A connector is disclosed with a transceiver and a socket on a substrate receiving the transceiver. The transceiver is movable within the socket into a locked position in a direction parallel to the substrate. The socket and the transceiver comprise complementary locking sections cooperating when the transceiver is in the locked position. The movement of the transceiver in the direction parallel to the substrate wipes the contacts of the substrate clean before the contacts of the substrate are positioned against respective contacts of the transceiver. 
         [0008]    In a releasable embodiment, the transceiver is movable within the socket between the locked position and a release position in a direction parallel to the substrate. The connector can for instance have a release member for moving the transceiver to the release position against the action of resilient members biasing the transceiver to the locked position. Such a release member may for example comprise at least one wedge wedging between a wall of the socket and a surface of the transceiver to exert a force against the action of the resilient members, when the wedge of the release member is pushed down. Such a release member does not need to interrupt the top face of the transceiver. Consequently, the complete top face can be used for heat dissipation, for instance by means of a heat sink. If a heat sink is used with relatively high pins or fins, a pressure tool can be used gripping over the pins or fins to press the release member. 
         [0009]    In specific embodiment the socket comprises an interposer having a lower side with contact pads connected to circuitry of the substrate, and a top side provided with an array of resilient contacts exerting an upward contact force. Suitable examples of such resilient contacts include land grid array (LGA) contacts. Such LGA contacts are resilient contact fingers, typically extending in the same direction. If LGA contacts are used, the direction of movement of the transceiver to the locked position may preferably coincide with the direction of the LGA contacts. 
         [0010]    In an alternative embodiment, no interposer is used. Also in that case, the substrate can be provided with an array of resilient contacts exerting an upward contact force, such as LGA contacts. 
         [0011]    If an interposer is used, the socket may for instance comprise inwardly bent support lips spacing the interposer from the substrate. For accurate positioning of the interposer, the socket may comprise inwardly extending positioners and fingers resiliently engaging side edges of the interposer to position the interposer against the positioners. 
         [0012]    The resilient members biasing the transceiver to the locking position can for example be formed by inwardly bent leaf springs at a distance above the interposer. The leaf springs can form part of the socket. In a specific embodiment, the socket is a single stamped metal sheet strip bent to connect its outer ends. In that case the support lips, leaf springs, positioners and/or resilient fingers can be formed by inwardly bent parts of the strip. 
         [0013]    To guide the transceiver in its movement to the locked position, the socket and the transceiver can for example be provided with complementary sliding guides defining the direction of that movement. If the socket comprises an interposer, the sliding guides can be formed by two recesses in the interposer receiving complementary projections of the transceiver. If the socket does not comprise an interposer, the guiding provisions can be formed by other parts of the socket. 
         [0014]    The connector can for example be an optical board connector or an electrical connector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be further explained under reference to the accompanying drawings. 
           [0016]      FIG. 1 : shows an exemplary embodiment of an optical on-board connector assembly; 
           [0017]      FIG. 2 : shows the assembly of  FIG. 1  in exploded view; 
           [0018]      FIG. 3 : shows the top side of a socket with an interposer of the assembly of  FIG. 1 ; 
           [0019]      FIG. 4 : shows the lower side of a socket with an interposer of the assembly of  FIG. 1 ; 
           [0020]      FIG. 5 : shows the socket with interposer of  FIGS. 3 and 4  in cross-section; 
           [0021]      FIG. 6 : shows the transceiver of the assembly of  FIG. 1 ; 
           [0022]      FIG. 7 : shows the lower side of the transceiver of  FIG. 6 ; 
           [0023]      FIG. 8 : shows the transceiver of  FIG. 6  from a different viewpoint. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0024]      FIG. 1  shows a connector assembly  1  comprising an on-board connector  2  and a complementary optical cable connector  3 . The on-board connector  2  comprises a transceiver  4  and a socket  5 , which is positioned on a printed circuit board  6  and which holds the transceiver  4  in place. The transceiver  4  has a receiving opening  7  for receiving the optical cable connector  3 . The transceiver  4  is provided with a release member  8  having a U-shape covering three sides of the transceiver  4 . 
         [0025]    The socket  5  holds an interposer  11  which is a board with contacts  12 ,  13  at both sides (see  FIGS. 3 and 4 ). The lower side of the interposer  11 , shown in  FIG. 4 , comprises an array of solder contacts  12 , in this case ball grid array (BGA) contacts for connection to circuitry of the printed circuit board  6 . On the top side (see  FIGS. 2 and 3 ) the interposer  11  is provided with land grid array (LGA) contacts  13 . The LGA contacts  13  are parallel resilient contact arms extending in a direction (arrow A in  FIG. 3 ) parallel to a diagonal axis of the interposer  11 . 
         [0026]    The socket  5  is made of a stamped sheet metal strip bent to a closed rectangular or square outline. Near one end  14  of the strip an opening  15  receives a narrow extension  16  of the opposite end  17  of the strip. The first end  14  is also provided with two opposite lips  18  received in matching openings  19  of the opposite end  17 . The four sides of the socket  5  have outwardly bent upper edges  21  and outwardly bent lower edges  22  mounted on the printed circuit board  6 . 
         [0027]    A first side  24  of the socket  5  is provided with two locking openings  25  near the upper edge  21  for locking the transceiver  4 , as will be explained hereafter. Just below the openings  25  the first side  24  comprises two inwardly bent support lips  26  for supporting the interposer  11 . Between the two support lips  26 , the first side  24  comprises rigid positioners  27  abutting the side edge of the interposer  11  when it rests on the support lips  26 . The next side  30  in clockwise direction is the side with the connected ends  14 ,  17  of the strip forming the socket  5  at one end of the second side  30 . At the opposite end the second side  30  comprises an inwardly bent leaf spring  31  at a level above the interposer  11 . A resilient finger  28  for accurately positioning the interposer  11  against the positioners  27  is located at the second side  30  between the opening  15  and the lips  18 . 
         [0028]    Near the resilient finger  28  the outer end  14  of the strip is extended with a lip  29  confining a recess for locking a complementary tooth  35  on the transceiver  5 , as explained hereinafter. 
         [0029]    The next side  32  in clockwise direction comprises a single support lip  26 , a single resilient finger  28  and two leaf springs  31  (see  FIG. 4 ). Finally, the fourth side  33  comprises two positioners  27  and a locking opening  25  for locking the transceiver  4  ( FIG. 5 ). The locking opening  25  is positioned near the corner with the third side  32 . 
         [0030]    Accordingly, the interposer  11  rests on three support lips  26 : two at the first side  24  and one at the opposite third side  32 . The support lips  26  space the interposer  11  from the circuit board  6 . The interposer is pressed against the four positioners  27  by the two resilient fingers  28  resulting in a very accurate positioning. Other numbers of resilient fingers or positioners can also be used, if so desired. The socket  5  comprises three inwardly bent leaf springs  31 . These do not engage the interposer  11 , but serve to bias the transceiver  4  into the locking position, as will be explained hereinafter. 
         [0031]    As shown in  FIG. 8  the backside of the transceiver  4  has two teeth  34 . Laterally extending teeth  35  are held at the sides of the transceiver  4  near the corners with the cable entry side. The teeth  34  at the back side and the laterally extending tooth  35  at the left side of the cable entry are spaced and dimensioned to fit into the openings  25  in the socket  5  when the transceiver  4  is in the locked position. Similarly, the laterally extending tooth  35  at the right side of the cable entry is dimensioned to fit below the lip  29  at the outer end  14  of the strip forming the socket  5  when the transceiver  4  is in the locked position. 
         [0032]    The release member  8  covers three sides of the transceiver  4 , leaving the cable entry side with the receiving opening  7  free. The back side of the release member  8  has two openings  36  receiving the teeth  35  in such a way that the teeth  35  can move up and down within the openings  36 . The backside of the release member also comprises a wedge  37  extending between the two openings  36 . The wedge  37  runs parallel to the upper and lower edges of the backside of the release member  8  and has a slanting lower wedge surface  38 . The laterally extending teeth  35  of the transceiver  4  are not covered by the release member  8 . At the side faces the transceiver  4  comprises a cam  39  cooperating with a matching opening  41  in the release member  8  to hold the release member  8  in place relative to the transceiver  4 . The opening  41  is dimensioned to allow vertical movement of the cam  39 . At one side face  40  the release member  8  is provided with a second wedge  42  with a sloping lower wedge surface  43 . The opposite side face  44  of the release member  8  does not have a wedge (see  FIG. 7 ). This side face  44  is flat, but does have an opening  41  receiving a vertically movable cam  39  symmetrically arranged relative to the cam  39  and opening  41  of the other side face  40  of the release member  8 . 
         [0033]    As shown in  FIG. 7 , the lower side of the transceiver  4  comprises two differently sized alignment pegs  45 ,  46 : a first peg  45  at the cable entry side near the flat side  44  of the release member  8  and a second peg  46  in the diagonally opposite corner. The first peg  45  has a larger diameter than the second peg  46 . The lower side face of the transceiver  4  comprises an array of contacts  47  to be connected to the LGA contacts  13  of the interposer  11 . 
         [0034]    At one of its corners the interposer  11  comprises a first recess  48  positioned near the connected ends  14 ,  17  of the strip forming the socket  5  (see  FIG. 3 ). The first recess  48  is dimensioned to receive the first peg  45  of the lower surface of the transceiver  4 . A second recess  49  is provided at the diagonally opposite corner of the interposer  11 . This second recess  49  is dimensioned to receive the second peg  46 . The shortest line from the first recess  48  to the second recess  49  extends in a direction coinciding with the direction of the LGA-contacts, indicated by arrow A in  FIG. 3 . 
         [0035]    When the transceiver  4  is pushed into the socket  5 , the pegs  45 ,  46  will be received by the corresponding recesses  48 ,  49  in the interposer  11 . The resilient leaf springs  31  bias the transceiver  4  in the direction of arrow A. During that movement, the transceiver wipes of the LGA contacts. This removes contaminations and contributes to an improved signal transfer. When the transceiver  4  is sufficiently pushed down against the resilient action of the LGA contacts  13 , the leaf springs  31  will push the teeth  34 ,  35  in the corresponding openings  25  in the first and fourth sides  24 ,  33  of the socket  5 , while the right side lateral tooth  35  is pushed below the lip  29 . This fixates the transceiver  4  into the locking position. The openings  25  and the lip  29  are positioned in such a way that the pressure on the LGA contacts  13  exerted by the poisoned transceiver is substantially equal. 
         [0036]    In the locked position the wedges  37 ,  42  rest on the upper edges of the socket  5 . The parts of the three side faces of the release member  8  below the wedges  37 ,  42  are located between the walls of the socket  5  and the transceiver  4 . 
         [0037]    To release the transceiver  4  the release member  8  can be pushed down. The two wedges  37 ,  42  of the release member  8  push the transceiver in a direction opposite to the direction of Arrow A against the action of the resilient leaf springs  31  of the socket  5  towards a release position. This movement is guided via the pegs  45 ,  46  in the recesses  48 ,  49  of the interposer  11 . In the release position the teeth  35  of the transceiver  4  are unhooked from the openings  25  in the socket  5 . The transceiver  4  is pushed upwardly by the resilient LGA contacts  13 , so the teeth  35  cannot re-enter the openings  25  in the socket  25 .