Patent Publication Number: US-6666694-B1

Title: Reduced profile EMI receptacle assembly

Description:
The present invention pertains to a receptacle assembly for shielding electromagnetic interference (EMI) and in more particular an EMI receptacle for receiving an electronic component therein such as an electronic or optoelectronic transceiver device for mounting to the EMI receptacle of a host device. 
     BACKGROUND OF THE INVENTION 
     Receptacles for receiving electronic devices are known by such terms as receptacles, guide rails, cages or sockets. In many applications, multiple receptacles are mounted to a motherboard in side-by-side orientation. Multiple motherboards may be mounted within a host device so that rows of receptacles are provided. Generally the motherboard forms a planer surface which abuts the exterior wall or chassis of the host device. A hole is made in the chassis or a separate faceplate is formed in the chassis in order to provide a port through with electronic devices may be inserted into the receptacle which is mounted on the motherboard. In some circumstances the end of the receptacle may protrude through the faceplate opening in order to guide the electronic component within the receptacle and into the host device. 
     Receptacles that are known include small form factor pluggable (SFP) transceiver receptacles as disclosed in Multi-Source Agreement (MSA) (SFF-80741) which discloses a receptacle to receive an SFP transceiver therein. The receptacle or receptacle disclosed in the MSA includes mounting posts along the bottom of the receptacle so that the mounting posts may be received in the upper surface of the motherboard so that the receptacle is mounted onto the motherboard and the entire receptacle protrudes above the upper surface of the motherboard. Likewise, the electrical connector which is surrounded by the receptacle is surface mounted to a land grid array pattern provided on the upper face of the motherboard. 
     In such devices, the receptacle may have a height and protrudes above the motherboard by approximately 0.385 inches. When multiple motherboards are stacked or aligned within a host device in order to provide rows of receptacles within the host device, the height of the receptacle provides a limiting factor and dictates the spacing between the motherboards. Therefore, in the above example, the motherboards of a host device could not be spaced closer than 0.385 inches. In fact, some clearance is desirable between the top of a receptacle and the bottom of a motherboard in order that no metal to metal contact or electrical interconnection is made between the top of the receptacle and the bottom of the adjacent motherboard and also to allow for air circulation for cooling. Due to such spacing limitations a host device such as a router, hub or switch can only accommodate a limited number of rows of receptacles. Since the width of a side of a host device has a limited size based on the location to which the host device will be oriented, such as on a rack in a computer room or in a wiring closet; only a limited amount of space is available on the host device for providing rows of receptacles. 
     As the bandwidth capacity of a host device is increased, it is desirable to have additional ports available for more and more electronic devices such as transceivers. One manner of increasing the number of ports available in a host device is to allow for additional motherboards to be stacked within the host device in order to provide additional rows of receptacles. However, due to the limitations discussed above, with regard to the height that the receptacle protrudes above the motherboard, additional rows or receptacles are difficult to add in the confined width of a host device. As well, relocating of the motherboard with respect to the cut-out opening in the bezel or faceplate of the host device provides for better cable management and cooling of the receptacles and for the electronic devices mounted therein. Therefore, it would be desirable to provide a receptacle and motherboard assembly which provides for a reduced profile of the receptacle above the motherboard so that additional motherboards may be stacked side by side in order to allow for additional rows of receptacles in a host device. Such a reduced profile receptacle and motherboard assembly is provided by the present invention. 
     SUMMARY OF THE INVENTION 
     A receptacle assembly is provided comprising a printed circuit board having a cut-out portion along an edge of the printed circuit board. The receptacle includes a receptacle opening for receiving an electronic component therein. At the end opposed to the receptacle opening a board receiving portion is located between a top surface and a bottom surface of the receptacle. The receptacle is mounted to the printed circuit board at the board receiving portion so that the receptacle is recessed within the cut-out and a height that the receptacle protrudes beyond a major surface of the printed circuit board is less than a total height of the receptacle. The printed circuit board may include a mounting footprint for receiving mounting members or tabs of the receptacle. The receptacle board receiving portion includes a cut-out area of the receptacle having a mounting member tab protruding therefrom for insertion into an aperture in the printed circuit board. 
     In an embodiment, the receptacle may include a shield flap attached to the receptacle adjacent the board receiving portion. The shield flap may include a mounting tab for insertion into the printed circuit board. The shield flap may be pivotally attached to the receptacle. In an embodiment, the shield flap may include a living hinge formed between the shield flap and the receptacle. The shield flap may substantially enclose the board receiving portion of the receptacle. The board receiving portion may attach to a first side of the printed circuit board and the shield flap may attach to a second side of the printed circuit board. In an embodiment, a first mounting tab of the board receiving portion may be received in a first aperture on the first side of the printed circuit board and protrude toward the second side of the printed circuit board and a second mounting tab of the shield flap may be received in a second aperture on the second side of the printed circuit board and protrude toward the first side. An electrical connector may be provided that straddle mounts to the printed circuit board at the cut-out and is adjacent the board receiving portion of the receptacle. A top frame and/or bottom frame for supporting the receptacle within the cut-out may be provided. 
     In another embodiment, a metallic receptacle is provided for receiving and shielding an electronic component received therein and the receptacle comprises a first end forming and opening for receiving the electronic device therethrough, a second end having a board mounting area formed by at least two sides of the receptacle recessed from a major body edge of the receptacle formed along a majority of the receptacle between the first end and the second end and a shield flap attached at the second end adjacent the board mounting area. The sides of the receptacle may include mounting tabs for mounting the receptacle to a first side of a printed circuit board. In an embodiment, the shield flap may include mounting tabs for attaching the shield flap to second side of the printed circuit board. The shield flap may substantially enclose the second end of the receptacle. The shield flap may be pivotally attached to the receptacle via a living hinge. In an embodiment, a top frame support may be provided at the first end of the receptacle in order to assist in supporting the first end of the receptacle within a cut-out portion of the printed circuit board within which the receptacle is mounted. The first end of the receptacle may be supported by a bottom support frame attached at the first end of the receptacle and supporting the first end within a cut-out portion of a printed circuit board within which the receptacle is mounted. The board mounting area may form an open area allowing for the insertion therethrough of an electrical connector. The electrical connector may be attached to a printed circuit board. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated. 
     FIG. 1 is an exploded perspective view of the receptacle and motherboard assembly of the present invention; 
     FIG. 2 is a side elevation partial view of a faceplate of a host device attached to a motherboard oriented in a preferred embodiment of the present invention; 
     FIG. 3 is a perspective view of the receptacle with a shield flap in an open position; 
     FIG. 4 is a perspective view of the receptacle of the present invention with the shield flap in a closed position; 
     FIG. 5 is a side elevation view of the receptacle of the present invention with the shield flap in an open position; 
     FIG. 6 is an enlarged perspective view of an electrical connector of the present invention mounted to the cut-out portion of the motherboard of the present invention; 
     FIG. 7 is a side elevation view of an electrical connector of the present invention; and 
     FIG. 8 is a perspective view of the receptacle and motherboard assembly of the present invention. 
    
    
     DETAILED DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT 
     The present invention is described with reference to a preferred embodiment that is depicted in FIGS. 1-8. Turning to FIG. 1 an exploded perspective view of a receptacle and motherboard assembly  100  is depicted having motherboard  50  with four receptacles  11 ,  12 ,  13 ,  14  shown elevated above the printed circuit board or motherboard  50  prior to assembly thereto. Each receptacle or cage  11 ,  12 ,  13 ,  14  are identical in construction and a description will be provided for the first receptacle  11  which will be a description for the other receptacles. The receptacle  11  includes a receptacle opening  21  at its first end  201 . Opposed to the receptacle opening  21  at a second end  202  of the receptacle  11  is a board receiving portion  31 . In a preferred embodiment the receptacle  11  is formed of a metallic material such as a stamped and formed sheet of stainless steel forming a five-sided structure having an open cut-out portion forming the board receiving portion  31  at a bottom second end of the receptacle  11 . However, alternative embodiments of the receptacle  11  may be provided formed of other materials such as metalized plastic. 
     The receptacle  11  may include mounting members, for example, tabs  33 ,  34  provided within a cut-out section which forms the board receiving portion  31  of the receptacle  11 . Adjacent the board receiving portion  31  is a metallic hood or shield flap  60 . The shield flap  60  in a preferred embodiment is attached to the bottom of the receptacle  11  via a living hinge which allows the shield flap  60  to pivotally rotate between an open position as shown in FIG. 1 and a closed position (shown in FIG.  4  and FIG.  8 ). However, in an alternate embodiment a metallic hood may be provided that is separately stamped and formed of metal sheet that may be attached to the bottom of the receptacle via soldering or other mechanical means after the receptacle is mounted to the printed circuit board  50 . In an embodiment, the metallic hood may form a four-sided structure that encloses the board receiving portion  31  of the receptacle  11  in order to shield a first edge  51  of the printed circuit board and complete the enclosure around an electrical connector mounted at the first edge  51 . However, the hood may also be curvilinear in form. The shield flap or metallic hood  60  may include tabs  61 ,  62 ,  63  for abutting the printed circuit board  50 . The receptacle  11  is secured to the printed circuit board  50  by mounting tabs  33 ,  34  engaging apertures  533 ,  534  and mounting tabs  35 ,  37  (shown in FIG.  3  and adjacent mounting tabs  33 ,  34 ) of the board receiving portion  31  being received in apertures of the first side  150  of the printed circuit board  50 . In an embodiment the mounting tabs  35  and  37  engage holes formed in the terminal ends of the tabs  64 ,  66  and are received in apertures on a second side  250  of the printed circuit board  50 . In an embodiment the tabs  35 ,  37  may protrude through the apertures  533 ,  534  exiting the second side of the printed circuit board  50 . The first side  150  provides an upper major surface of the printed circuit board upon which a majority of the components such as integrated circuits are mounted. 
     A rectangular shaped cut-out area  55  is formed at the first edge  51  of the printed circuit board  50  forming an offset edge  56 . Electrical connectors  71 ,  72 ,  73  are mounted to the printed circuit board  50  at the offset edge  56  of the cut-out area  55 . In a preferred embodiment, straddle mount electrical connectors  71 ,  72 ,  73  are provided to mount to the offset edge  56  of the cut-out  55 . A fourth electrical connector (not shown) is mounted next to the third electrical connector  73 . Each electrical connector  71 ,  72 ,  73 ,  74  corresponds with each corresponding receptacle  11 ,  12 ,  13 ,  14  which is mounted to surround the electrical connectors  71 ,  72 ,  73 . In a preferred embodiment the electrical connectors  71 ,  72 ,  73  receive a card edge connection of an electronic component, such as a transceiver which is mounted within the receptacle  11 . It should be understood that although four receptacles  11 ,  12 ,  13 ,  14  and four electrical connectors  71 ,  72 ,  73 ,  74  are depicted in FIG. 1 the present invention may provide a receptacle and printed circuit board assembly for any number of receptacles and connectors. As well, the receptacle  11  of the present invention may accommodate any type of electrical connector mounted in alternate orientations, such as to the printed circuit board or to the receptacle itself. 
     A preferred method of assembling the present invention will be described with reference to FIG. 1. A motherboard  50  is provided having cut-out  55  provided therein. The apertures such as the mounting tab receiving apertures  533 ,  534  are provided in the motherboard  50  and adjacent the apertures are provided a footprint having a land grid array pattern for receiving straddle mount tails of electrical connectors  71 ,  72 ,  73 . The electrical connectors are attached to the offset edge  56  of the cut-out area  55  by sliding the straddle mount tails over the offset edge  56  of the printed circuit board  50  and a friction fit is provided in order to hold the electrical connectors  71 ,  72 ,  73  in place at the provided footprint of the motherboard  50 . The footprint includes solder pads that may be reflowed in order to connect the solder tails  87  (FIG. 6) of the electrical connectors  71 ,  72 ,  73  to the printed circuit board  50  and provide an electrical connection thereto. A bottom frame support  81  is then attached to the printed circuit board  50  adjacent the edge  51  of the printed circuit board  50 . 
     Each receptacle  11 ,  12 ,  13 ,  14  is then mounted within the cut-out  55  so that the mounting tabs  33 ,  34  are received in the apertures  533 ,  534 . In a preferred embodiment the apertures  533 ,  534  are bores that are coated with solder paste. As the receptacle  11  is mounted to the printed circuit board  50  the shield flap  60  is inserted through the cut-out  55  and protrudes below the bottom face of the second side  250  of the printed circuit board  50 . The shield flap  60  is then rotated up towards the second side  250  of the printed circuit board  50  so that the mounting tabs  64 ,  66  are engaged by mounting tabs  35 ,  37  (FIGS.  3  and  4 ). In an embodiment, the mounting tabs  35 ,  37  have formed latches that are received by holes in the mounting tabs  64 ,  66 . The apertures  533 ,  534  for receiving mounting tabs  33 ,  34  in an alternate embodiment, may not be coated with solder paste. However, such apertures  533 ,  534  in an embodiment have a ground plane exposed therein to make electrical contact with the mounting tabs  33 ,  34  in order to ground the receptacle thereto. A top frame support  82  is then mounted over the receptacle opening ends  21  of the receptacles  11 ,  12 ,  13 ,  14 . In an embodiment, fasteners such as thumb screws  83 ,  84  are inserted through apertures at the ends of the top frame and bottom frame supports  81 ,  82  in order to secure the frame supports  81 ,  82  to the printed circuit board  50  and secure the receptacle opening ends  21  of the receptacles  11 ,  12 ,  13 ,  14  to the printed circuit board  50 . Each frame includes alignment tabs  85 ,  86  and  95 ,  96 , respectively, in order to align each receptacle  11 ,  12 ,  13 ,  14  laterally on the frame support  81 ,  82  so that cut-out  121 ,  122  of the faceplate  120  will align with the end of the receptacle. 
     The entire assembly  100  may then be placed in a reflow oven in order to reflow the solder provided at the footprint of the pads for the contact tails  87  of the electrical connectors  71 ,  72 ,  73  and to reflow the solder paste (if present) within the apertures  533 ,  534  that receive the mounting tabs  33 ,  34 . After the reflow process, the assembly  100  is allowed to cool and the solder to cure which helps secure the mounting tabs  33 ,  34  within the apertures in order to rigidly secure the receptacles  11 ,  12 ,  13 ,  14  to the printed circuit board  50 . 
     In a further method of assembly in a preferred embodiment, the motherboard  50  is then mounted within a host device. Additional motherboards may also be stacked next to the motherboard  50  in order to provide rows of receptacles  11 ,  12 ,  13 ,  14  within a host device. A faceplate  120  (FIG. 2) may then be placed along the outer edge  51  of the motherboard  50  in order to enclose the edge  51  of the host device. In a preferred embodiment, the faceplate  120  is a metallic/conductive material which provides for shielding. The faceplate  120  abuttingly connects with ground tabs  41  of the receptacle openings  21  in order to provide for a EMI shielded assembly  100 . It may be understood that the mounting of multiple motherboards  50  within a host device may occur where the motherboard  50  is either in a horizontal or vertical orientation. Therefore, the reference to rows of cages  11  or receptacles also refers to columns of receptacles or cages when the motherboard  50  is oriented vertically. 
     Turning to FIG. 2, a side elevation partial view of a host device is depicted having a faceplate  120  having a first cut-out  121  and a second cut-out  122 , that provide for two ports in communication with receptacles mounted therein. Motherboard or printed circuit board  50  has an edge  51  and offset edge  56 . The view depicted in FIG. 2, for the sake of simplicity, does not include the receptacles  11 ,  12 ,  13 ,  14  mounted to the printed circuit board  50 . It may be understood that in a preferred embodiment the receptacles  11 ,  12 ,  13 ,  14  are mounted to the printed circuit board  50  and the faceplate  120  is placed over the receptacle opening ends  21  of each receptacle  11 ,  12 ,  13 ,  14 . Each rectangular shaped receptacle opening  21  protrudes through the rectangular shaped cut-outs  121 ,  122  of the faceplate  120 . The mounting of the receptacles  11 ,  12 ,  13 ,  14  in the cut-out area  55  of the printed circuit board  50  adjacent the offset edge  56  provides for a reduced profile receptacle assembly. The profile is defined by the height that the top surface of the cages  11  protrudes above the upper major surface  150  of the printed circuit board  50 . 
     As may be understood in view of the above description, a portion of each receptacle  11 ,  12 ,  13 ,  14  is recessed below the upper major surface  150  of the printed circuit board  50 . By recessing a portion of each receptacle  11 ,  12 ,  13 ,  14  below the major surface  150 , the upper portions of the receptacles  11 ,  12 ,  13 ,  14  do not protrude above the major surface  150  of the printed circuit board  50  as much as if there were no cut-out  55  and the receptacles  11 ,  12 ,  13 ,  14  were mounted directly onto the top of the major surface  150  of the printed circuit board  50 . Due to the recessed mounting, the profile or height h between the upper major surface  150  of the printed circuit board and the top of each receptacle  11 ,  12 ,  13 ,  14  is greatly reduced. In FIG. 2 the top of the receptacle is depicted as the top of the cut-outs  121 ,  122 . In a preferred embodiment, the cut-outs  121 ,  122  of the faceplate  120  very closely engage the top portion of the receptacles  11 ,  12 ,  13 ,  14  and when measured from the major surface  150  of the printed circuit board  50  are, therefore, approximately equal to height h. Therefore, h as identified in FIG. 2, represents the height of the receptacles  11 ,  12 ,  13 ,  14  above the major surface  150  of the printed circuit board  50 . In a preferred embodiment h is less than the total height of the cage  11  and in particular h=0.244 inches. However, it may be understood that the present invention provides for the increased density of vertical stacking of rows or columns of receptacles of motherboards which is an improvement over prior art devices. In the specific example of an SFP cage constructed according to the MSA, a reduced profile assembly is provided when h is between 0.0 and 0.385 inches. 
     As discussed above, the faceplate  120  in a preferred embodiment is a metallic material in order to provide for shielding of components mounted on the printed circuit board  50 . Ground tabs  41  are provided at the receptacle opening end  21  of the receptacle  11  (see FIG.  1 ). The ground tabs  41  abut against the cut-outs  121 ,  122  of the faceplate  120 . The ground tabs  41  in a preferred embodiment are also metallic and provide an electrical connection between the receptacle  11  and faceplate  120 . Such an electrical connection between the ground tabs  41  and faceplate  120  helps to reduce EMI and provide for grounding of the receptacle  11 ,  12 ,  13 ,  14  to the same ground potential of the chassis faceplate  122 , to generally earth or chassis ground. Therefore, it may be understood that upon insertion of an electrical device such as a transceiver through the cut-outs  121 ,  122  and into the receptacles  11 ,  12 ,  13 ,  14  the transceiver may provide for static discharge to the faceplate  120  or receptacles  11 ,  12 ,  13 ,  14  and upon operation, the transceiver&#39;s electromagnetic radiation from its high speed circuitry will be shielded and will not harm other components mounted on the printed circuit board  50  adjacent the cut-out area  55 . 
     Turning to FIG. 3, a perspective view of the receptacle  11  is shown from a rear view having mounting tab  33  shown at one side of the board receiving portion  31 . Additional mounting tabs  35 ,  36 ,  37  and  38  are also disclosed protruding down into the board receiving portion  31 . Shield flap  60  is depicted having tabs  61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67 ,  68  and  69  protruding therefrom. In a preferred embodiment tabs  64  and  66  act as mounting tabs to secure the shield flap  60  in its closed position attached at the board receiving portion  31 . Opposite the board receiving portion  31  is the receptacle opening end  21  of the receptacle  11 . In a preferred embodiment the receptacle  11  is formed of a single sheet of metal and is stamped and formed to provide the receptacle defining a box like structure and is secured in its box like structure via side flaps  12 . 
     As was discussed with regard to FIG. 1, the assembly of the receptacle  11  to the motherboard  50  may be understood more particularly with regard to the view shown in FIG.  3 . The initial step of mounting the receptacle  11  to the motherboard  50  provides for the insertion of mounting tabs  33 ,  35 ,  36 ,  37  and  38  into apertures located in the first side  150  of the printed circuit board  50 . The board receiving portion  31  of the receptacle  11  is mounted onto the offset edge  56  of the printed circuit board  50  so that a majority of the receptacle  11  protrudes beyond the offset edge  56  of the printed circuit board and is received within the cut-out  55  of the printed circuit board  50 . The shield flap  60  is then pivotally moved on its living hinge  80  so that mounting tabs  64 ,  66  engage mounting tabs  33 ,  37 . As is shown in FIG. 4, the receptacle  11  is depicted having shield flap  60  in its closed position. In order to simplify the view of the receptacle  11 , it is depicted without a printed circuit board  50  mounted at the board receiving portion  31  so that the mounting tabs  33 ,  35 ,  36 ,  37 ,  38 ,  64 ,  65 ,  66  may be viewed. Each of these mounting tabs are inserted in apertures from the top and bottom of the printed circuit board  50  in order to securely attach the receptacle  11  to the printed circuit board  50  and also to completely enclose the receptacle  11 . It may be understood that when the receptacle  11  is mounted over electrical connector  71 ,  72 ,  73  the shield flap  60  surrounds the bottom of the electrical connector  71  and encloses the board receiving portion  31  of the receptacle  11 . 
     As is shown in FIG. 5, the receptacle  11  is depicted having the shield flap  60  in its open position. The receptacle  11  has the board receiving portion  31  formed by a cut-out edge  42  having the mounting members or tabs  44 ,  43  protruding therefrom on a first side and  35  on a second side provide for the quick and easy mounting of the receptacle  11  to the offset edge  56  of the printed circuit board  50 . In a preferred embodiment, the mounting members  33 ,  34  are press-fit pins having a center hole  32  so that upon insertion in apertures  533 ,  534 , respectively (FIG.  6 ), the sides of the press-fit pins  33 ,  34  may compress and provide a friction fit in order to maintain the pins  33 ,  34  within the apertures  533 ,  534  and retain the receptacle  11  on the printed circuit board  60 . The compression of the pins  33 ,  34  against the sides of the apertures  533 ,  534  in an embodiment also provide for an electrical connection to a ground plane exposed within the apertures  533 ,  534 . The cut-out edge  42  is formed approximately midway between a top surface and a bottom surface (each providing a major body edge) of the receptacle  11  at a second end  202 . The distance between the top and bottom surface of the cage  11  provides a total height of the cage  11 . The simple action of closing of the shield flap  60  simultaneously secures the receptacle  11  to the printed circuit board  60  while also providing a completely shielded enclosure of the receptacle  11 . 
     FIG. 6 depicts electrical connector  74  mounted to printed circuit board  50 . FIG. 6 is an enlarged view of printed circuit board  50  of FIG. 1 rotated 180° to depict the mounting tails  87  of the electrical connector  74  mounted to the offset edge  56  forming cut-out  55  of printed circuit board  50 . Electrical connector  74  is shown adjacent to electrical connector  73  which is adjacent electrical connectors  72  and  71  disclosed in FIG.  1 . FIG. 7 also depicts the electrical connector  74  including mounting tails  87 ,  88 . The mounting tail  87  is received on the first side  150  of the printed circuit board  50  and the mounting tail  88  is received on the second side  250  of the printed circuit board. Each mounting tail  87 ,  88  represents each of the nine other tails located in a top (FIG. 6) and bottom row adjacent the tails  87 ,  88  depicted in the preferred embodiment depicted in FIG. 7 on each side of the electrical connector  74  providing twenty total contact tails formed as part of the twenty total contacts. However, many other types and sizes of electrical connectors can be used with the present invention. 
     The printed circuit board  50  includes apertures  534 ,  533 ,  535 ,  536 ,  537 ,  538  and  539  for receiving mounting tabs  34 ,  33 ,  35 ,  36 ,  37 ,  38  and  39  (see FIG. 3) respectively, therein. These apertures define a footprint area which also includes the mounting pads for receiving the contact tails  87  thereon of the printed circuit board  50 . 
     Turning to FIG. 8 a fully assembled receptacle and motherboard assembly  100  is depicted having receptacles  11 ,  12 ,  13 ,  14  mounted to printed circuit board  50  so that the majority of the receptacles  11 ,  12 ,  13 ,  14  are received within cut-out  55 . The board receiving portion  31  is mounted to the offset edge  56  of the printed circuit board  50 . The receptacle opening end  21  is shown captured by the top frame support  82  and bottom frame support  81  mounted to the motherboard  50  so that the receptacle openings  21  protrude beyond the first edge  51  of the printed circuit board  50 . It can be seen from this view that the receptacles  11 ,  12 ,  13 ,  14  are recessed below the upper major surface  150  of the printed circuit board and have a reduced profile and allow for the tighter stacking of multiple motherboards  50  in order to provide additional rows or columns of receptacles  11 ,  12 ,  13 ,  14  in a host device. 
     The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and is not as a limitation. While particular embodiments have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicant&#39;s contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.