Patent Publication Number: US-2018034211-A1

Title: Electrical connector assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electrical connector assembly, and particularly to the electrical receptacle connector adapted to be mated with a plug. 
     2. Description of Related Art 
     Currently QSFP-DD Specification Rev. 0.1 discloses a 1×1 QSFP-DD module has eight electrical lanes. Each of the eight electrical lanes of the QSFP runs at the rate of 25 Gbit/s or 50 Gbit/s, thereby the QSFP-DD module support 200 Gbit/s or 400 Gbit/s Ethernet applications of. The QSFP-DD module has an electrical receptacle. The electrical receptacle has an insulative housing and four rows of electrical terminals received in the insulative housing. Each of the electrical terminals has a soldering section. Two rows soldering sections of the two top rows of the electrical terminals are offset in a longitudinal direction from two rows soldering sections of the two bottom rows of the electrical terminals. The present invention relates to an electrical connector assemblies, especially to the terminal layout and the terminal module assembly thereof and the so-called FP5 connector following the previous designs of which the provisional application has a Ser. No. 62/367,098 filed on Jul. 26, 2016 and another Ser. No. 62/399,272 filed on Sep. 23, 2016. As the QSFP-DD plug and receptacle has a similar interface with the FP5 plug and the receptacle. Therefore, it is need to prevent them to make a mis-mating. 
     An improved electrical connector assembly is desired to offer advantages over the related art. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an connector assembly having means to prevent them to make a mis-mating with other type of connector assembly. 
     To achieve the above-mentioned object, an electrical connector assembly comprising a receptacle connector comprising an insulative housing; and a plurality of contacts received in the housing; and a plug connector for being mated with the receptacle connector, comprising an enclosure; and a printed circuit board enclosed in the enclosure with an end for being inserted into the insulative housing to mate with the contacts; and wherein at least one pair of slots are formed on one of the receptacle and the plug connector, and at least a corresponding pair of ribs are formed on the other to mate with the at least one pair of slots for not only providing an anti-mismating function but also a restriction function for holding the plug connector in position with respective to the receptacle. 
     To achieve the above-mentioned object, an electrical connector assembly comprising a first electrical connector assembly including a first plug connector and a first receptacle connector adapted to be mated with each other, the first plug connector including a first cover with at least two opposite first plates defining a first receiving space with therebetween a first mating tongue in a vertical direction, the first receptacle connector including a first frame housing with therein a first mating cavity adapted to receive said first mating tongue therein; and a second electrical connector assembly including a second plug connector and a second receptacle connector adapted to be mated with each other, the second plug connector including a second cover with at least two opposite second plates defining a second receiving space with therebetween a second mating tongue in the vertical direction, the second receptacle connector including a second frame housing with therein a second mating cavity to receive the second mating tongue therein, the first receiving space being similar to the second receiving space, the first mating cavity being similar to the second mating cavity; wherein in the second connector assembly, the second cover of the second plug connector forms at least one rib on at least one of said two opposite second plates and one notch in at least one of said two opposite second plates, and the second frame housing of the second receptacle connector forms at least one slot adapted to receive said rib, and one protrusion adapted to be received within said notch during when said second plug connector and the second receptacle connector are mated with each other while the protrusion of the second receptacle connector prevents the first plug connector from being incorrectly mated therewith, and the rib of the second plug connector prevents the first receptacle connector form being incorrectly mated therewith. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1(A)  is a front perspective view of an electrical connector assembly including a plug connector adapted to be mated with a receptacle connector according to the first embodiment of the invention; 
         FIG. 1(B)  is a rear perspective view of the electrical connector assembly of  FIG. 1(A) ; 
         FIG. 1(C)  is an elevational view of the plug connector of  FIG. 1(A) ; 
         FIG. 2  is an exploded perspective view of the electrical connector assembly of  FIG. 1(A)  wherein the heat sink of the plug is disassembled; 
         FIG. 3  is a further exploded perspective view of the electrical connector assembly of  FIG. 2  wherein a part of the metallic enclosure of the plug connector is removed; 
         FIG. 4  is a further exploded perspective view of the plug connector of  FIG. 3 ; 
         FIG. 5(A)  is a further front exploded perspective view of the plug connector of  FIG. 4 ; 
         FIG. 5(B)  is a further rear exploded perspective view of the plug connecter of  FIG. 4 ; 
         FIG. 5(C)  is a bottom view of a bottom half portion of the metallic enclosure of the plug connecter of  FIG. 4 ; 
         FIG. 6(A)  is an elevational view of one surface of the printed circuit board used within the plug connector of  FIG. 2 ; 
         FIG. 6(B)  is an elevational view of the surface of the printed circuit board of used within the plug connector of  FIG. 2 ; 
         FIG. 6(C)  is an elevational view of one surface of another embodiment of the printed circuit board used within the plug connector of  FIG. 2 ; 
         FIG. 7(A)  is a front perspective view of the receptacle connector of  FIG. 1 ; 
         FIG. 7(B)  is a rear perspective view of the receptacle connector of  FIG. 1 ; 
         FIG. 8(A)  is a front exploded perspective view of the receptacle connector of  FIG. 7(A) ; 
         FIG. 8(B)  is a rear exploded perspective view of the receptacle connector of  FIG. 7(A) ; 
         FIG. 9(A)  is a further front exploded perspective view of the receptacle connector of  FIG. 8(A) ; 
         FIG. 9(B)  is a further rear exploded perspective view of the receptacle connector of  FIG. 8(A) ; 
         FIG. 10(A)  is a cross-sectional view of the receptacle connector and the partial plug connector of  FIG. 1  along a center line of the plug connector; 
         FIG. 10(B)  is a cross-sectional view of the receptacle connector and the partial plug connector of  FIG. 1  along a line offset from a center line of the plug connector; 
         FIG. 11  is a partly perspective view of the plug connector initially mated with the receptacle connector of the  FIG. 1 ; 
         FIG. 12  is aside view of the plug connector of  FIG. 1  with the metallic enclosure removed; 
         FIG. 13(A)  is a front perspective view of an electrical connector assembly including a plug connector adapted to be mated with a receptacle connector according to the second embodiment of the invention; 
         FIG. 13(B)  is a front perspective view of an electrical connector assembly including a plug connector adapted to be mated with a receptacle connector according to the first embodiment of the invention with a differently shaped EMI shielding block; 
         FIG. 14(A)  is a front perspective view of the electrical connector assembly of  FIG. 13(A)  wherein the plug cable connector is removed from the receptacle connector; 
         FIG. 14(B)  is a front perspective view of the electrical connector assembly of  FIG. 13(B)  wherein the plug cable connector is removed from the receptacle connector; 
         FIG. 15(A)  is a perspective view of the EMI shielding block of the plug cable connector of  FIG. 13(A) ; 
         FIG. 15(B)  is a perspective view of the EMI shielding block of the plug cable connector of  FIG. 13(B) ; 
         FIG. 15(C)  is another perspective view of the EMI shielding block of the plug cable connector of  FIG. 13(B) ; 
         FIG. 16  is a perspective view of the plug cable connector with the EMI shielding block is removed away from the housing of the plug cable connector of  FIG. 13(B) ; 
         FIG. 17  is a further exploded perspective view of the plug cable connector of  FIG. 16 ; 
         FIG. 18  is a perspective view of an electrical connector assembly according to a third embodiment of the invention; 
         FIG. 19  is a perspective view of the electrical connector assembly of  FIG. 18  wherein the cage enclosing the receptacle connector is removed; 
         FIG. 20  is a perspective view of the electrical connector assembly of  FIG. 19  wherein the plug cable connector is mated with the receptacle connector; 
         FIG. 21(A)  is a downward front perspective view of the plug cable connector of  FIG. 20  wherein the upper molded floating housing is removed therefrom; 
         FIG. 21(B)  is an upward front perspective view of the plug cable connector of  FIG. 21(A) ; 
         FIG. 22(A)  is a downward exploded perspective view of the plug cable connector of  FIG. 21(A) ; 
         FIG. 22(B)  is an upward exploded perspective view of the plug cable connector of  FIG. 22(A) ; 
         FIG. 23(A)  is a downward front perspective view of the housing of the plug cable connector of  FIG. 22(A)  with the upper fixed housing and the upper floating housing removed therefrom; 
         FIG. 23(B)  is a downward rear perspective view of the housing of the plug cable connector of  FIG. 22(A)  with the upper fixed housing and the upper floating housing removed therefrom; 
         FIG. 24  is a downward front perspective view of the housing and the printed circuit board of  FIG. 23(A)  with the upper fixed housing and the upper floating housing removed therefrom; 
         FIG. 25  is a downward rear perspective view of the housing with the printed circuit board of  FIG. 24  with the upper fixed housing and the upper floating housing removed therefrom; 
         FIG. 26(A)  is a top view of a printed circuit board assembly during manufacturing wherein each printed circuit board is used within the plug cable connector of  FIG. 18 ; 
         FIG. 26(B)  is a bottom view of a printed circuit board assembly of  FIG. 26(A) ; 
         FIG. 27(A)  is an illustrative view to show mating between the printed circuit board and the receptacle connector; 
         FIG. 27(B)  is another illustrative view to show the mating between the printed circuit board and the receptacle connector; 
         FIG. 28  is a across-sectional view, taken along a center vertical plane in the front-to-back direction, of the mated plug cable connector and receptacle connector of the electrical connector assembly of  FIG. 18 ; 
         FIG. 29  is a cross-sectional view, taken along a transverse vertical plane, of the plug cable connector of  FIG. 18 ; 
         FIG. 30  is another across-sectional view, taken along another transverse vertical plane, of the plug cable connector of  FIG. 18 ; 
         FIG. 31(A)  is a front downward perspective view of the receptacle connector used with the plug cable connector of  FIG. 18  according to another embodiment of the invention; 
         FIG. 31(B)  is a rear upward perspective view of the receptacle connector of  FIG. 31(A) ; 
         FIG. 32  is a perspective view of an electrical connector assembly according to a fourth embodiment of the invention; 
         FIGS. 33  is a perspective view of the electrical connector assembly of  FIG. 32  with the cage removed therefrom; 
         FIGS. 34  is another perspective view of the electrical connector assembly of  FIG. 33 ; 
         FIGS. 35  is a perspective view of the electrical connector assembly of  FIG. 32  with the plug connector initial alignment with the receptacle connector; 
         FIGS. 36  is a perspective view of the electrical connector assembly of  FIG. 32  with the plug connector final alignment with the receptacle connector; 
         FIGS. 37  is a front downward perspective view of the receptacle connector used with the plug cable connector of  FIG. 32 ; 
         FIGS. 38  is a rear upward perspective view of the receptacle connector of  FIG. 37 ; 
         FIG. 39(A)  is a perspective view of an electrical connector assembly named FP5 according to a fifth embodiment of the invention; 
         FIG. 39(B)  is another perspective view of the electrical connector assembly of  FIG. 39(A) ; 
         FIG. 40  is an assembled perspective view of the electrical connector assembly of  FIG. 39(A) ; 
         FIG. 41  is an exploded perspective view of the electrical connector assembly of  FIG. 40 ; 
         FIG. 42(A)  is a front downward perspective view of the electrical receptacle of  FIG. 41 ; 
         FIG. 42(B)  is a rear downward perspective view of the electrical receptacle of  FIG. 42(A) ; 
         FIG. 42(C)  is a rear upward perspective view of the electrical receptacle of  FIG. 42(A) ; 
         FIG. 43  is an exploded perspective view of the plug connector of  FIG. 41 ; 
         FIG. 44(A)  is a front further exploded perspective view of the plug connector of  FIG. 43 ; 
         FIG. 44(B)  is a rear exploded perspective view of the plug connector of  FIG. 43 ; 
         FIG. 45  is an exploded perspective view of the cage and the electrical receptacle of  FIG. 41 ; 
         FIG. 46  is a top view of the plug connector without the top cover of  FIG. 41 ; and 
         FIG. 47  is a cross-sectional view of the assembled electrical connector assembly of  FIG. 40 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-6 (B) and  12 , a first embodiment of the invention includes a cable connector or plug connector  200  mated with a receptacle connector  500  adapted mounted upon a printed circuit board (not shown). The cable connector  200  includes a metallic enclosure  210  with a detachably attached heat sink  250  to enclose a printed circuit board  280  with electronic components  282  thereon wherein the enclosure  210  includes upper and lower parts assembled to each other in the vertical direction. In this embodiment, the heat sink  250  includes associatively a thermal pad  252  thereunder. A thermal block  284  is sandwiched between the electronic component  282  and the heat sink  250  to dissipate heat from the electronic component  282  to the heat sink structure  250 . Notably, the thermal pad  252  and the thermal block  284  are of the same character so as to be deemed as one piece. A plurality of pads  286  are formed on a front region of the printed circuit board  280  in one row with a 0.5 mm pitch, compared with the pads in two rows with a 0.8 mm pitch used in QSFP-DD version. A plurality of pads  288  formed on a rear region of the printed circuit board  280  in two rows. A cable  300  includes a plurality of differential wires  302  soldered upon the corresponding pads  288 . The printed circuit board  280  forms a pair of side notches  289  for engagement with the corresponding side posts  219  on an interior surface of the enclosure  210 . 
     Compared with the previous design, there are some other features in the instant invention. The conductive pads  286  are arranged in one row in a 0.5 mm pitch. 0.5 mm pitch PCB contact to pad true position must be tightly controlled in order to maintain adequate functionality. To assure the precise position of those conductive pads  286 , a pair of fiducial positions  281  are defined in the printed circuit board  280  for easy reference. It is noted that the width dimension of the instant invention is same with the traditional QSFP and QSFP-DD. Therefore, for not interchanging with those two other type connectors, in the instant invention a front end of the metallic enclosure  210  further includes an additional plate  212  with a pair of ribs  214  thereon for coupling to the corresponding slots in the receptacle connector illustrated later. To facilitate heat dissipation, a hollow column structure  216  is unitarily extends inwardly/vertically in the enclosure  210  for providing an air intake hole  218  therein and through a through hole  285  in the printed circuit board  280  so as to communicate the exterior air with the interior air in the enclosure  210 . The through hole  285  of the printed circuit board  280  is accurately drilled. 
     In this embodiment, the heat sink  250  is detachably attached to the enclosure  210  in a rotational manner wherein the heat sink  250  includes the latching structure  254  and the enclosure  210  includes the recess structure  213 . Notably, the drawings shown in this embodiment in  FIGS. 1-6 (B) does not completely show the detailed structure regarding the interengagement structures about the heat sink  250  and the enclosure  210 . Understandably, it may require some deformable/deflectable/removable structures thereabouts for performing removability thereof. 
     As shown in  FIGS. 7(A) - 11 , the receptacle connector  500  includes an insulative housing  502  forming a mating cavity  504  to receive the front region of the printed circuit board  280  therein. A terminal module assembly  590  includes an upper terminal module  510  and a lower terminal module  530  stacked with each other with a shielding plate module  570  therebetween in a vertical direction and commonly received within the housing  502 . The upper terminal module  510  includes a plurality of upper terminals  512  retained in an upper insulator  514  and an upper rear insulator  515 ; the lower terminal module  530  includes a plurality of lower terminals  532  retained in a lower insulator  534 ; and the shielding plate module  570  includes a metallic shielding plate  572  retained in a lower rear insulator  574 . The lower rear insulator  574  includes a pair of positioning posts  576  to be inserted into the corresponding positioning holes  506  of the insulative housing  502 . A plurality of grooves  578  are formed in the rear side of the lower rear insulator  574  to receive the tail sections of the corresponding upper terminal  512 . Similarly, the rear side of the insulative housing  502  forms a plurality of grooves  507  to receive the tail sections of the corresponding lower terminals  532 . Understandably, the upper terminal module  510 , the lower terminal module  530  and the shielding plate module  570  may be equipped with pre-assembling or vertically aligning structures to pre-assemble the whole terminal module  590  and simultaneously insert the whole terminal module  590  into the insulative housing  502  instead of assembling in a sequence of the lower terminal module  530 , the shielding plate module  570  and the upper terminal module  510 . 
     Compared with the previous design, in the instant invention the receptacle connector  500  provides a pair of alignment slots  505  to receive the corresponding ribs  214  on the plug connector  200 . In this arrangement, the plug connector  200  can be inserted into the corresponding receptacle connector  500  while can not be inserted into the similar receptacle connector lacking such alignment slots as the so-called QSFP-DD receptacle connector Understandably, to further prevent the QSFP-DD plug connector from being inserted into the receptacle connector  500 , in another embodiment (detail can be see in the fourth embodiment) the receptacle connector  500  may need to form an addition protrusion and the plug connector  200  may need to form a corresponding recess to receive such a protrusion therein. Notably,  FIG. 6(C)  shows another embodiment of the printed circuit board  290  of the plug connector forms a slot  291  and the corresponding receptacle connector  200  forms a ribbed structure (not shown) in the mating cavity to mate therewith. Therefore, the QSFP-DD plug connector can not be inserted into the receptacle connector due to such an additional protrusion. This mutual prevention between two similar interfaces of the connector assembly may also be referred to the copending application Ser. No. 14/839,880 filed Aug. 28, 2015. 
     Referring to  FIGS. 13(A) - 17 , a second embodiment of the invention electrical connector assembly  10  includes a plug cable connector  100  and a receptacle connector (not shown in this embodiment while being shown in the third embody) enclosed within a metallic cage  130  and mounted upon a mother board  140 . The basic structures of the plug cable connector and those of the receptacle connector may be referred to aforementioned previously filed provisional application wherein the plug cable connector  100  includes s lower metallic die cast housing  102 , an upper metallic die cast housing  104  sandwiching a printed circuit board  106  therebetween in the vertical direction. A replaceble heat sink  108  is removably attached upon the upper housing  104 . An actuator  110  and the corresponding pulling tape  112  are associatively assembled upon at least one of the lower housing  102  and the upper housing  104 . A cable  114  is connected to a rear end portion of the printed circuit board  106  while the front end portion of the printed circuit board is located in a front portion of the upper housing  104  and the lower housing  102  and functioning as a mating tongue. Different from the previous design, a pair of ribs  103  are formed on two opposite lateral side of the lower housing  102  and a pair of ribs  105  are formed on two opposite lateral side of the upper housing  104  for coupling to the corresponding four slots  602  formed at four corners of the insulative housing  610  of the receptacle connector  600 , which are not shown in this embodiment while being shown in the third embody. Through this rib-slot arrangement, the plug cable connector only mates with the correct receptacle connector while being unable to mate with a similar receptacle connector having a similar interface configuration with the receptacle connector while without the corresponding slots at four corners. This anti-mismating structure is analogous to the anti-mismating structure disclosed in the aforementioned previously filed provisional application for preventing the instant plug cable connector from being mated with the QSFP-DD receptacle connector. An EMI shielding block  116 , which is essentially made of molded conductive plastic, is intimately mounted upon the upper housing  104  behind the heat sink  108  for radiation absorption consideration. The upper face of the EMI shielding block  116  contacts the metal cage  300  and the bottom face of the EMI shielding block  116  contacts the upper surface of the upper housing  104 . A plurality of passageways  118  extend through the EMI shielding block  116  in a front-to-back direction, and a plurality of through holes  120  extend through the EMI shielding block  116  in the vertical direction to allow air passing for heat transfer. 
     Referring to  FIGS. 18-30 , in the third embodiment electrical connector assembly  20  includes a plug connector  400  and a receptacle connector  600  enclosed within a metallic cage  670  and mounted upon a mother board  680 . Compared with the previous design, there are some other features in the instant invention. The receptacle connector  600  comprises an insulative housing  610  having four walls  611 , and defining four slots  602  formed in four corners of said insulative housing  610 . The housing of the plug connector  400  includes a rear upper fixed housing  410  and a rear lower fixed housing  420  assembled with each other via the screws  490  to enclose a printed circuit board  450 , and further includes a front upper floating housing  430  and a front lower floating housing  440  assembled with each other via the screws  490  wherein the rear upper fixed housing  410  forms posts  412  received within the corresponding holes  436  of the front upper floating housing  430 , and similarly the rear lower fixed housing  420  forms a cavity  422  to receive a corresponding protrusion  442  of the front lower floating housing  440 . Notably, the coupling between the rear upper fixed housing  410  and the front upper floating housing  430 , and that between the rear lower fixed housing  420  and the front lower floating housing  440  are loose to allow a floating therebetween in the transverse direction, and understandably, another floating along the vertical direction may optionally exit, if necessary. In other words, a clearance exists between the coupling parts of the fixed housing  410 ,  420  and the floating housing  430 ,  440 . In this embodiment, the upper floating housing  430  and the lower floating housing  440  are made by molded plastic and the upper fixed housing  410  and the lower fixed housing  420  are made by die cast metal wherein the upper fixed housing  410  is equipped with the heat sink structure  470 . The upper floating housing  430  comprises a horizontal upper plate and a pair of upper ribs  405  for mating with corresponding slot  602 . The bottom floating housing  440  comprises a horizontal lower plate and a pair of lower ribs  403  for mating with corresponding slot  602 . The front upper floating housing  430  and a front lower floating housing  440  can be accurately aligned to the receptacle connector  600  by the upper ribs  405  and the lower ribs  403  mated with the corresponding slots  602 , respectively. 
     A spacer  460  has a pair of posts  462  extending downwardly through the corresponding holes  424  of the lower fixed housing  420  and the corresponding holes  444  of the lower floating housing  440  for restricting relative movement therebetween along the front-to-back direction. On the other hand, the lower floating housing  440  forms an upward post  446  extending upwardly through the corresponding hole  422  of the printed circuit board  450  into the hole  432  in the downward pole  434  of the upper floating housing  430 . As shown in  FIG. 28 , the printed circuit board  450  is sandwiched between the upper floating housing  430  and the lower floating housing  440 . 
       FIGS. 26(A) and 26(B)  show the printed circuit board  450  is made from a large board with bridges  455  linked between every adjacent two printed circuit boards  450  for precisely forming the corresponding pads thereon. The bridges  455  keep the individual printed circuit board  450  stable during coaching. Fish mill each printed circuit board  450  mating area relative to each local fiducial. 
       FIGS. 31(A) and 31(B)  show the another embodiment of the receptacle connector  620 . The receptacle connector  620  includes an insulative housing  622  with a front cavity  624  for receiving a mating tongue of a complementary plug connector, and a rear cavity  626  to receive a terminal assembly  627  therein. An upper metallic ground plate  628  with the grounding fingers  629  thereon is located upon an upper surface of the housing  622 , and a lower metallic ground plat  630  with the grounding fingers  631  is located upon a bottom surface of the housing  622 . 
     Referring to  FIGS. 32 to 38 , in the fourth embodiment electrical connector assembly  30  includes a plug connector  310  and a receptacle connector  320  enclosed within a metallic cage  330  and mounted upon a mother board  340 . The plug connector  310  is similar with the plug cable connector  100  of the second embodiment. But this embodiment don&#39;t comprises a heat sink and an EMI shielding block. The printed circuit board  310  of the plug connector  310  defines a notch  311  which is similar with the slot  291  showing in  FIG. 6(C) . In  FIGS. 35 and 36 , when the plug connector  310  is mated with the receptacle connector  320 , the ribs  315  of the upper portion is initially alignment with the corresponding slots  321  of the receptacle connector  320 , and then the ribs  313  of the lower portion is final alignment with the corresponding slots  321  of the receptacle connector. 
     Referring to  FIGS. 39(A)  to  47 , in the fifth embodiment electrical connector assembly  900  belonging to the so-called FP5 connector assembly which is similar to the aforementioned QSFP-DD connector assembly, including a plug connector  930  to mate with a receptacle  950  within a metallic cage  910  and mounted on a printed circuit board  920 . It is noted that even though the mating port between the plug connector  930  and the receptacle  950  is somewhat similar to that between the QSFP-DD plug connector and the QSFP-DD receptacle, the cage  910  is relatively higher than the QSFP-DD cage. It is because in the QSFP-DD connector assembly the heat sink is attached upon the top cover of the plug connector after the plug connector is assembled into the cage while in the FP5 connector assembly  900  the heat sink  970  and the EMI shielding block  916  is attached or unitarily formed upon the top cover of the plug connector  930  and commonly inserted into the cage  910  with the top cover  932 . Similar to the QSFP-DD plug connector, the plug connector  930  includes a metallic base  931  and a metallic top cover  932  commonly defining a receiving cavity to receive a paddle card  934  therein. A cable  936  includes a plurality of wires (not shown) soldered upon the paddle card  934 . An actuator  940  is movable along the front-to-back direction for releasing the plug connector  930  from the cage  910 . As mentioned in the previous provisional application, the top cover  932  forms a pair of alignment ribs  942 , and the base  931  forms a pair of alignment ribs  944  so as to received within the corresponding slots  980  in the receptacle  950  while being stopped by the QSFP-DD receptacle for preventing mis-mating. The receptacle  950  is similar to what is disclosed in the previously filed provisional application and includes an insulative housing  952  enclosing a terminal module sub-assembly  954 . The housing  952  further forms a protrusion  978  to be received within the notch  946  in the top cover  932 . Understandably, because of the protrusion  978  on the FP5 receptacle connector  950 , the QSFP-DD plug connector can not mate with the FP5 receptacle  950 ; in opposite, because of alignment ribs  942 ,  944  of the FP5 plug connector  930 , the QSFP-DD receptacle connector can not mate with the FP5 plug connector  930 . Without such foolproof arrangement, the QSFP-DD and the FP5 may mistakenly interchangeable with each other due to the similar interface therebetween. The metallic cage  910  defines a plurality of through holes  911  in communication with the slots formed on the sink  970  and the EMI shielding block  916  that forms air channels for heat sink.