Patent Publication Number: US-2006003628-A1

Title: Terminal assembly for small form factor connector

Description:
REFERENCE TO RELATED APPLICATIONS  
      This application claims priority of prior U.S. Provisional Patent Applications Nos. 60/584,424, filed Jun. 30, 2004 and 60/584,420, also filed Jun. 30, 2004.  
    
    
     BACKGROUND OF THE INVENTION  
      This invention relates to electrical connector assemblies and, more particularly, to an small sized electrical connectors having a stacked arrangement.  
      Electrical connectors adapted for mounting to printed circuit boards are known in the art and are commonly used for connection between two electrical communication devices. In order to ensure that a proper connection has been made and therefore a link is created between the electrical communication devices, indicators may be incorporated into circuits on the printed circuit board. These indicators are typically light emitting diodes (LEDs). which are turned on when a circuit is completed between the mating connectors and the communication devices. Additionally LEDs can be mounted on the printed circuit board to indicate a number of other conditions including the passage of communications signals between the two communication devices, indication of power, or indication that an error in transmitting the signals has occurred.  
      A problem arises with these type of connectors because the terminals of the connector are usually stitched in from the rear of the connector. Stitched connector typically require a means to align the tails of the connector terminals to facilitate the insertion of the connector onto a circuit board. The use of tail aligners increase the overall size of the connector, thereby increasing the printed circuit board “real estate” occupied by the connector.  
      Small size connectors must usually be inserted into an exterior shielding cage by way of a bottom opening. When a dual connector of a stacked arrangement, i.e., one which is intended to mate with two electronic modules in a vertically spaced arrangement, is desired, such a connector cannot be practically inserted into a shielding cage by way of a bottom opening because of the intervening horizontal wall of the shielding cage.  
      The present invention is therefore directed to a terminal assembly for a connector having a construction that overcomes the aforementioned disadvantages and which engages a shielding cage intended to provide electromagnetic interference shielding around electronic modules that engage the connector.  
     SUMMARY OF THE INVENTION  
      Accordingly, it is a principal object of the present invention to provide a small form factor circuit board connector in a stacked configuration having engagement faces thereof spaced vertically apart.  
      Another object of the present invention is to provide a dual engagement connector component that is engageable with a light pipe assembly, the dual engagement connector component having two engagement areas vertically spaced apart from each other on the component and which are each surrounded by a metal shield component, the shield component defining two distinct module-receiving bays which are separated by an intervening space, the light pipe assembly extending from the connector component forwardly through the intervening space to provide at least a pair of indicator lights near the front of the module-receiving bays, the light pipe assembly engaging the sides or front of the connector component.  
      Yet another object of the present invention is to provide a connector for use with a shielded assembly having two bays, the connector having two engagement slots that receive edges of circuit cards that are associated with electronic modules, the connector having a plurality of terminal assemblies, each of which holds a plurality of conductive terminals in a selected arrangement, the terminals being housed in an insulative skeletal frame.  
      A further object of the present invention is to provide a connector having a small form factor and dual card engagement slots spaced apart vertically in a housing of the connector, the connector housing having at least one slot formed on a front face thereof for receiving engagement members of a shielding assembly.  
      Still another object of the present invention is to provide a terminal assembly for the aforementioned connectors, wherein the terminal assemblies each include an insulative frame that houses a plurality of conductive terminals, and the frame includes an engagement member that extends forwardly from the frame and engages a ledge of the housing to assist in orienting the terminal assembly in the connector cavity.  
      The present invention accomplishes these and other object by way of its structure. A connector housing is provided with an internal cavity formed therein that opens to the rear of the connector housing. This cavity accommodates a plurality of individual terminal assemblies. Each terminal assembly includes a dielectric frame that supports a plurality of conductive terminals. The terminals each have a right-angle configuration, with tail portions of the compliant pin style preferably disposed along one edge of the frame and with individual contact portions disposed along another and preferably adjacent edge of the terminal assembly frame.  
      These terminal assemblies are inserted into the cavity of the connector housing from its rear face so that the contact portions thereof are received within terminal-receiving cavities formed in the connector housing. The terminal assemblies also preferably include engagement members which may take the form of clips disposed along the same edge as the contact portions. These clips engage a shoulder formed in the connector housing within the connector cavity.  
      The internal cavity of the connector housing accommodates the terminal assemblies as a block. A shoulder member is provided therein for the terminal assemblies to engage and maintain their orientation within the housing. The front face of the connector housing may be provided with slots or cavities disposed between the two card engagement slots. These other slots receive corresponding opposing engagement members, preferably in the form of tabs, that extend from a portion of an exterior shielding assembly and which portion provides an intervening shielding wall of an associated shielding assembly that divides the assembly into two distinct module-receiving bays. These slots are preferably positioned outside of the openings into which the light pipe engagement members are inserted.  
      The front of the connector component may have one or more engagement slots of cavities formed therein which engage a light pipe assembly. By this frontal engagement, the sides of the connector housing need not be modified to engage the light pipes in any fashion, so as to maintain the reduced size of the connector component. The light pipe assembly may include hooks that are integrally formed with the light pipes as a preferable means of attachment. The light pipe assembly may utilize distinct first and second pairs of light pipes, and each such pair may utilizes its own set of engagement hooks for engaging the connector component in the manner described above.  
      The contact portions that project along one edge of the terminal assemblies have insulative portions disposed between them, preferably to maintain their spacing and these spacer portions have offset edges that project outwardly and transverse to the contact portion so that they serve to interlock with each other and maintain the contact portions aligned laterally through the group of terminal assemblies. Openings are formed in the skeletal framework of the assemblies and these openings define air channels that follow the path of the terminals to provide an air interface between lateral sets of terminals. The channels include cross bars for strength and these are offset as between adjacent terminal assemblies so that a complete air path is established for each pair of terminals, rather than an interrupted one.  
      These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will now be described by way of example with reference to the following figures of which:  
       FIG. 1  is an exploded perspective view of a portion of a connector assembly constructed in accordance with the principles of the present invention;  
       FIG. 2  is a perspective assembled view of the portion of the connector assembly shown in  FIG. 1 ;  
       FIG. 3  is a perspective view of a connector housing incorporated into the assembly shown in  FIG. 1 ;  
       FIG. 4  is perspective view of a first embodiment of a light pipe assembly that may be used with the connector assembly of  FIGS. 1-3 ;  
       FIG. 5  is perspective view of a second embodiment of a light pipe assembly incorporated into the connector assembly of the present invention;  
       FIG. 6  is a perspective view of the light pipe assembly of  FIG. 4  incorporated into the connector assembly, and extending along the sides thereof;  
       FIG. 7  is a partial cutaway perspective view showing the light pipe assembly of  FIG. 5  incorporated into the connector assembly, and specifically disposed within the exterior shield assembly and partially within the space dividing the two module-receiving bays of the connector assembly;  
       FIG. 8  is the same view of the connector assembly of  FIG. 7 , but with the shield assmebly exterior wall shown in place;  
       FIG. 9  is an exploded view of a third embodiment of the invention wherein the light pipes engage the connector component of the assembly by way of slots disposed in the front face of the connector components, and which are partially contained within the space separating the two module-receiving bays of the connector assembly;  
       FIG. 10  is the same view as  FIG. 9 , but with the modules shown in engagement with their associated connector component and with the shielding cage assembly removed for clarity;  
       FIG. 11  is a perspective view of only the light pipe assembly of  FIG. 9 ;  
       FIG. 12  is the same view as  FIG. 11 , but with the light pipe end cap shown exploded away from the light pipes for clarity;  
       FIG. 13  is a perspective view of only the two pairs of light pipes of  FIG. 12 ;  
       FIG. 14  is a top plan view of the light pipe and end cap assembly of  FIG. 11 , taken along line  14 - 14  thereof;  
       FIG. 15  is a frontal elevational view of the light pipes of  FIG. 13 , taken along line  15 - 15  thereof;  
       FIG. 16  is an enlarged detail perspective view of  FIG. 9 , illustrating only the light pipe and end cap assembly engaged with their associated connector component and positioned in place on a circuit board;  
       FIG. 17A  is a perspective view illustrating the right-side light pipe in engagement with the connector component of  FIG. 16 ;  
       FIG. 17B  is the same view as  FIG. 17A , but with the light pipe removed from engagement with the connector component to illustrate better the manner of engagement between the two components;  
       FIG. 18  is a perspective view of a small from factor connector assembly utilizing another, or fourth, embodiment of a light pipe assembly constructed in accordance with the principles of the present invention;  
       FIG. 19  is a perspective view, partially exploded, of the connector assembly of  FIG. 18 ;  
       FIG. 20  is the same view as  FIG. 19 , but with the light pipe and connector assembly shown separated from the circuit board and the shield rear end removed to illustrate the manner of insertion of the light pipe-connector assembly into the shielding cage;  
       FIG. 21  is the same view as  FIG. 20 , but fully exploded to illustrate all of the components of the overall assembly in which the present invention is used;  
       FIG. 22  is a perspective view illustrating the light pipes spaced apart from their associated connector component;  
       FIG. 23A  is a perspective view of the light pipe-connector component assembly, and taken from the rear thereof to illustrate the manner in which the light pipes extend along the sides of the connector component to face the circuit board illuminators;  
       FIG. 23B  is the same view as  FIG. 23A , but sectioned along line B-B thereof;  
       FIG. 24A  is a top plan view of the first, or inner pair of light pipes;  
       FIG. 24B  is a front elevational view of  FIG. 24A  showing the inner pair of light pipes;  
       FIG. 25A  is a top plan view of the second, or outer, pair of light pipes;  
       FIG. 25B  is a front elevational view of  FIG. 25A , showing the outer pair of light pipes;  
       FIG. 26A  is a top plan view of the first and second pairs of light pipes nested together;  
       FIG. 26B  is a front elevational view of  FIG. 26A , showing the two pairs of light pipes in line together;  
       FIG. 27  is a perspective view of another alternate embodiment of a light pipe, endcap and connector assembly;  
       FIG. 28  is an exploded view of  FIG. 27 ;  
       FIG. 29  is a perspective view of a small form factor connector constructed in accordance with the principles of the present invention and which utilizes individual terminal assemblies;  
       FIG. 30  is an exploded view of  FIG. 30 , illustrating the terminal assemblies removed from their position within the connector housing;  
       FIG. 31  is the same view as  FIG. 29 , but taken from the rear, illustrating the internal structure of the connector cavity, including the terminal-receiving slots of the connector housing and the terminal assembly engagement ledge of the connector housing;  
       FIG. 32  is a rear perspective view of  FIG. 29 , with alternating ones of the terminal assemblies illustrated in place within the connector cavity;  
       FIG. 33  is a perspective view of a terminal assembly used in the connector of  FIG. 29 ;  
       FIG. 33A  is a perspective view of the terminal assembly of  FIG. 33 , illustrating its right side;  
       FIG. 33B  is a front end view of two of the terminal assemblies of  FIG. 33  joined together;  
       FIG. 33C  is a front elevational view of the two terminal assemblies of  FIG. 33B  opened, but aligned along their rear edge to illustrate the locations of the support frames thereof along opposing faces of the terminal assemblies;  
       FIG. 33D  is an enlarged detail view of the offset locations of the dielectric frame crossbars and how they do not impede the passage of air through the air channel defined by the frame terminal openings  
       FIG. 34  is a sectional view of the terminal assembly, illustrating the lead frame in place within its insulative skeletal frame;  
       FIG. 35  is a sectional view of the connector of  FIG. 29  mounted on a circuit board and disposed within an exterior shielding assembly;  
       FIG. 36  is a front elevational view of the connector housing of  FIG. 29 ;  
       FIG. 37  is a rear elevational view of the connector housing of  FIG. 36 , but with the terminal assemblies removed to illustrate the interior of the connector housing more clearly;  
       FIG. 38  is a sectional view of the connector housing of  FIG. 37 ;  
       FIG. 39  is a sectional view of the connector assembly of  FIG. 36 , illustrating a terminal assembly in place within the connector housing internal cavity; and,  
       FIG. 40  is a perspective view of an array of the connectors of the invention in place upon a circuit board and mated together with portions of an exterior shielding assembly.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      A connector assembly  10  of the present invention will now be described generally with reference to  FIGS. 1-3 . The connector assembly  10  is designed for mounting on a printed circuit board  11 . Connector assembly  10  comprises a connector housing  12  defining a pair of ports  14 ,  16  each adapted for receiving a portion of a mating connector (not shown). Herein, the housing port  14  will be referred to as the “lower port”, and housing port  16  will be referred to as the “upper port”, but it will be understood that such terms as “upper”, “lower”, etc. are used in this description to facilitate an understanding of the invention and are not intended to be limiting.  
      Upper and lower ports  14 ,  16  each have a plurality of conductive terminals  21  mounted therein for engaging complementary terminals of a mating connector (not shown). To permit space for latching mechanisms for releasably securing connector assembly  10  in a mated condition with a complementary mating connector, a cavity  18  may be formed between upper port  16  and lower port  14  of connector housing  12 . Recesses  20  may be formed in side portions of housing  12 , for purposes to be described below. Recesses  14  may be in communication with housing cavity  18 .  
      Connector housing  12  may be molded from an insulative, thermoplastic material. The terminals are mounted in the upper port  16  and the lower port  14  and each terminal has contact portions at an end thereof (not shown) for engaging complementary contact portions of the terminals of the mating connector, and tail portions  22  projecting rearwardly from the contact portions and extending downwardly toward printed circuit board  11  for electrical connection to respective traces thereon via through holes formed in (or surface mount pads formed on a surface of) printed circuit board  11 . A tail aligner  24  may be attached to connector housing  12  using any one of a variety of known methods, such as a snap-fit, press-fit or mechanical fasteners. The tail aligner  24  includes a plurality of through holes  26  formed therein and which are configured to match the arrangement of terminal tail portions  22  extending downward toward printed circuit board  11 . The tail aligner  24  is mounted onto tail portions  22  of the terminals in the direction of arrow “A” ( FIG. 1 ) and it sits on the surface of the circuit board  11 .  
      A pair of shielding cage assemblies  28 ,  30  are secured to connector housing  12 , with the cage assemblies including a lower cage assembly  28  that is secured to housing  12  to substantially enclose lower port  14  thereof, and an upper cage assembly  30  that is secured to the housing  12  to substantially enclose the upper port  16  thereof. The cage assemblies  28 ,  30  are typically formed using a material, such as sheet metal or plated plastic, which conducts and guides magnetic and electric field energy so as to aid in shielding circuit elements positioned proximate connector assembly  10  from electromagnetic interference (EMI).  
      The lower cage assembly  28  typically includes two interengaging pieces, a lower base component  32  and a lower cover component  34 . The lower base component  32  has a general U-shaped configuration when viewed from the front or rear ends,  36 ,  38  respectively. As such, the lower base component  32  typically includes three sides, or walls: a base or bottom wall  40  and two sidewalls  42 ,  44  that extend upwardly from the bottom wall  40  and which are spaced apart from each other to define a channel  46  therebetween, into which a portion of the connector housing  12  fits. As seen in  FIGS. 1 and 2 , the front and rear portions of lower base component  32  are left open.  
      The lower base component  32  is stamped and formed from metal. The lower base component  32  may alternatively be formed using other conductive materials, such as metal-plated plastic or the like. Lower cover component  34  may also be formed is a similar manner. Generally, the cover component  34  has a length that matches a corresponding length of lower base component  32 , and a width that is equal to or slightly greater than a corresponding width of the lower base component  32 . The lower cover component  34  is bent, into a general U-shaped configuration when looking at it from its front end  50 . In this fashion, it includes top wall  52  and two spaced-apart side walls  54 ,  56 . Lower base component  32  and lower cover component  34  interengage along respective sidewalls thereof the form an enclosure for at least partially enclosing lower housing Port  14  of connector housing therein. As seen in  FIGS. 1 and 2 , the front and rear portions of the lower cage assembly  28  are left open. Details of this type of shielding cage are provided in U.S. Pat. No. 6,443,768, which issued on Sep. 3, 2002 and is incorporated herein by reference.  
      The structure of upper cage assembly  30  is similar to that of lower cage assembly  28  and it includes two interengaging pieces: an upper base component  58  and an upper cover component  60 . The upper base component  58  has a bottom wall  62  and two spaced-apart sidewalls  64 ,  66 . The upper cover component  60  has a top wall  72  and two spaced apart sidewalls  74 ,  76 . These sidewalls  74  and  76  interengage the upper base component as shown in order to form an enclosure similar to that formed by lower cage assembly  28 , for at least partially enclosing an upper housing port  16  of the connector housing  12 . In addition, sidewalls  74 ,  76  of upper cover component  60  also extend toward printed circuit board  11  to substantially enclose side portions of both upper cage assembly  30  and lower cage assembly  28 .  
      The lower base component  32  may be provided with mounting pin portions  48  that are stamped out of the bottom wall  40  thereof and which are formed, or bent, so that they extend vertically with respect to the lower base bottom wall  40 , and generally in the same plane as the sidewalls  42 ,  44 . The mounting pin portions  48  are formed in a desired pattern to engage and mate with corresponding mounting holes on printed circuit board  11 . Similar mounting pin portions  80  may be formed to extend along lower edges of extended sidewalls  74 ,  76  of the cover member  60  to engage mounting holes in printed circuit board  11 . Connector assembly  10  also includes a separate rear wall  78  that is attachable to the upper and lower cage assemblies  28 ,  30 . The rear wall  78  forms an enclosure surrounding the terminal tail portions  22 , tail aligner  24  and the rear portion of connector housing  12  when attached to cage assemblies  28 ,  30 , and the rear wall  78  includes mounting pin portions  80  extending from its bottom and extending vertically. The pin portions  80  engage mounting holes on printed circuit board  11 .  
      Referring to  FIGS. 4-7 , a light pipe assembly  82 , is shown as part of the overall connector assembly  10 . The light pipe assembly  82   a  of  FIG. 4  will be referenced for the purpose of describing the basic components of the light pipe assemblies. However, it will be understood that light pipe assembly  82   b  of  FIG. 5  has the same basic features as light pipe assembly  82   a . Light pipe assembly  82  includes at least one light pipe  84  manufactured from a material suitable for carrying light, such as a plastic or glass. The pipes  84  are illustrated as pairs of pipes, with each pair shown extending alongside the shielding cage assembly of the connector assembly.  FIGS. 4 &amp; 5  show assemblies which are formed using multiple light pipes. The light pipes  84  may be color-coded and each light pipe  84  has a light-receiving input face  86 , a light emitting output or display face  88 , and a body portion  90  extending between the input and output faces. Light pipes  84  are shaped to carry light signals from input faces  86  through body portions  90  to output faces  88 .  
      Portions of light pipes  84  may be affixed to one or more support members  92 . Support members  92  provide a framework for positioning and securing light pipes  84  with respect to each other and with respect to cage assemblies  28 ,  30 . Thus, portions of support members  92  may be formed so as to enable engagement with features on one of cage assemblies  28 ,  30 . Support members  92  may be formed integral with light pipes  84 . When the light pipe assembly  82  is mounted to cage assemblies  28 ,  30 , input faces  86  of each light pipe  84  will be positioned so as to reside opposite a respective light source such as an LED on the circuit board  11 .  
      As shown in  FIGS. 4 and 6 , a light pipe assembly  82   a  is externally mounted with respect to cage assemblies  28 ,  30 .  FIG. 4  and  6  show one possible configuration, in-which two pairs of light pipes are spaced apart vertically and connected to a pair of support members  92   a . Light pipe assembly  82   a  may be connected to one or more of the cage assemblies  28 ,  30  using any one of several known methods. Examples of possible attachment methods include a mating-type connection between complementary features formed in light pipe assembly  82   a  and cage assembly  28 ,  30 , mechanical fasteners, or adhesives. A portion of light pipe assembly  82   a  may also be secured to printed circuit board. One or more light pipe assemblies  82   a  may also be mounted along multiple sides of connector assembly. Thus, the light pipe assembly  82   a  may be configured in any desired manner to enable attachment to an existing connector assembly and to convey light between light emitting elements and light receiving elements having any one of a variety of spatial locations with respect to the connector assembly.  
      The shapes of light pipes  84   a  and the dimensions and positioning of support members  92   a  may be chosen to convey light between light emitting elements and light receiving sensors having a wide variety of locations in relation to connector assembly  10 . For example, as seen in  FIG. 6 , the configurations of light pipes  84   a  and support members  92   a  may be specified such that light pipe input faces  86   a  will receive light from respective LED&#39;s positioned on the circuit board  11  at various distances from connector assembly  10 . Also, the configurations of light pipes  84   a  and support members  92   a  may be specified such that light pipe output faces  88   a  will emit light to light receiving sensors located at any one of a variety of distances from printed circuit board  11 .  
      Referring to  FIG. 5 a  light pipe assembly  82   b  may be provided that includes one or more pairs of individual light pipes arranged in pairs. Each assembly  82   b  can be seen to include a pair of adjacent light pipes  84   b  that are attached to one or more support members  92   b . The light pipes  84   b  each opposing input faces  86   b , output faces  88   b  and body portions  90   b  that extend between the input and output faces  86   b ,  88   b . In this embodiment, the light pipes are configured to be mounted within the upper cage cover component  60  as shown by the alternate embodiment arranged in  FIG. 7 . In this embodiment, the pipes extends within the connector housing recess  20  and cavity  18  formed between housing upper port  16  and housing lower port  14 .  
      The light pipe assembly  82   b  may extend along a portion of tail aligner  24 , behind connector housing  12  and the light pipe assembly  82   b  may be secured to the connector housing  12  such that light pipe input faces  86   b  reside opposite respective LED&#39;s mounted on printed circuit board  11  and light pipe output faces  88   b  reside opposite respective light receiving sensors (not shown) mounted on a separate item of electronic equipment. Body portions  90   b  are formed so as to connect input faces  86   b  and output faces  88   b  for conveying light from LED&#39;s to the light receiving sensors located proximate output faces  88   b.    
      As may be seen in  FIG. 5 , the input faces  86   b  of light pipes  84   b  may be arranged in a “front-rear” configuration with respect to the mating direction of connector assembly  10  indicated by arrow “A”. The body portions  90   b  of the light pipes  84   b  include vertical portions  96   b  extending upward from printed circuit board  11  and terminating in right angle bends  98   b . Horizontal portions  100   b  of light pipes  84   b  extend from right angle bends  98   b  toward a front portion of the connector assembly, terminating in a transition region, generally designated  102   b . It may be seen from  FIG. 5  that horizontal portions  100   b  extending forward from right angle bends  98   b  have an “over-and-under” orientation.  
      Referring to  FIGS. 5 and 7 , it may be desired to arrange output faces  88   b  of light pipes  84   b  in a “side-to-side” configuration with respect to the connector assembly mating direction. Thus, the configuration of light pipes  84   b  must transition from the “over-and-under” orientation of horizontal portions  100   b  to the “side-to-side” configuration. This transition is shown best in  FIG. 5 . The transition in the configuration of the light pipes between right angle bends  98   b  and output ends  88   b  is achieved by forming, in transition region  102   b , angled portions  104   b  in each of the body portions of the light pipes. The transition region  102   b  preferably resides within housing cavity  18 .  
       FIG. 5  shows one possible arrangement of angled portions  104   b  in transition region  102   b . At points on the light pipe body portions  90   b  which are located within the housing cavity  18 , the body portion  90   b  of the bottommost light pipe  84   b  angles inward and upward, while the body portion  90   b  of the top most light pipe  84   b  angles outward and downward. The straight sections  106   b  of the body portions  90   b  then proceed from angled portions  104   b  toward a front portion of connector assembly  10  proximate the connector receiving openings in cage assemblies  104   b . As seen in  FIG. 5 , the body portions  90   b  may be angled such that straight sections  106   b  are spaced apart from each other and spaced approximately the same distance from printed circuit board  11 .  
      A support member  92   b  may be positioned between body straight sections  106   b  proximate angled  104   b  to position and secure the light pipe straight sections  106   b  with respect to each other and with respect to connector housing  12 . The width of support member  106   b  may be set to provide and maintain a desired predetermined spacing-between straight sections  106   b . Also, the length of support member  92   b  may be set to provide a press fit between upper cage base component  58  and lower cage cover component  34  when light pipe assembly  82   b  is inserted into the cavity  18  formed between the upper port  16  and lower port  14  of the connector housing. The support member  92   b  may also be plated with a metallic material to form a conductive member extending between upper cage assembly base component  58  and lower cage assembly cover component  34 . This provides additional grounding contact between cage assemblies  28  and  30 .  
       FIGS. 7 and 8  show that portions of light pipe straight sections  106   b  that include output faces  88   b  may be received in a shroud, or end cap  108 . The end cap  108  may be preferably formed using conductive materials to provide some degree of EM shielding. The end cap  108  secures the light pipe output faces  88   b  in a pattern, and provides additional EMI shielding for the overall connector assembly. For these purposes, the end cap  108  may be disposed to create intimate contact with both the upper cage assembly  58  and the lower cage assembly  36  and may be connected to a grounding member on the printed circuit board  11 .  
      In  FIGS. 7 and 8 , two light pipe assemblies  82   b  are embodied in two pairs of spaced apart light pipes  84   b  extending along opposite sides of connector housing  12 . In this embodiment, the light pipe assemblies  82   b  reside within housing recesses  20 , within upper cage cover component  60 , and within the cavity  18  formed between upper port  16  and lower port  14 . As such, the light pipe assembly  82   b  resides within the existing printed circuit board “footprint” of the connector assembly as defined by connector housing  12  and the cage assemblies that enclose the housing. Thus, this embodiment of the connector assembly incorporates a light pipe assembly therein without occupying additional space on printed circuit board  11 .  
      Assembly of the connector assembly  10  of  FIGS. 1, 2  and  6  will now be described. In a first step, the terminals may be press-fit into connector housing  12 . Terminal tail portions  22  are then inserted into tail aligner holes  26  and the tail aligner  24  is secured to connector housing  12 , thereby securing tail portions  22  with respect to housing  12 . The upper and lower cage assemblies  58 ,  36  are then secured over the connector housing  20  to upper and lower housing ports  14  and  16 , respectively.  
      The rear wall  78  of the cage assembly is then attached to the shielding cage assembly over the upper and lower assemblies  30 ,  28  and the upper cover component  60  to enclose terminal tail portions  22 , tail aligner  24  and to close off the rear portion of connector housing  12 . The rear wall  78  is generally secured in intimate contact with one or more walls of each of upper cage assembly base component  58 , upper cage assembly cover component  60 , lower cage assembly base component  32  and lower cage assembly cover component  34 . As stated previously, mounting pin portions  80  may also be formed on the shielding cage rear wall  78  in a desired pattern to engage and mate with corresponding mounting holes on the circuit board  11 . These holes may be plated through holes which are electrically coupled to circuit traces on printed circuit board  11 . These circuit traces are connected to one or more grounding features, thereby providing a grounding path for electromagnetic energy flowing through cage assemblies  28  and  30 . After securing rear wall  78  to upper and lower cage assemblies  28  and  30 , the connector assembly  10  may be electrically attached as a single unit to the printed circuit board  11 .  
      Assembly of the second embodiment of connector assembly  12  will now be described with reference to  FIGS. 1, 2 ,  7  and  8 . In a first step, the terminals are press-fit into connector housing  12 . Terminal tail portions  22  are then inserted into tail aligner holes  26  and tail aligner  24  is secured to connector housing  12 , thereby securing tail portions  22  with respect to housing  12 . In this embodiment, the lower cage assembly  28  is then secured to the connector lower housing port  14 , and the base portion  58  of the upper cage assembly  30  is then attached to the connector upper housing port  16 . The light pipe assembly  82   b  is then press-fit into housing recess  20  and the housing cavity  18 . Upper cage assembly cover component  60  is then attached to upper cage assembly base component  60 , thereby enclosing light pipe assembly  82   b  within side walls of upper cover component  60 . The spacing between the upper and lower cage assemblies  30 ,  28  defines a cavity that extends lengthwise of the connector assembly and this cavity accommodates the horizontal extent of the light pipe assemblies.  
      The rear wall  78  may then attached to cage assemblies  28 ,  30  to enclose terminal tail portions, tail aligner  24  and the rear portion of connector housing  12  as described above. After securing rear wall  78  to upper and lower cage assemblies  30  and  28 , connector assembly  10  may be electrically attached to printed circuit board  11 .  FIG. 9  illustrates a different connector  201  that supports a plurality of conductive terminals  203 , each terminal of which may be stitched into rear openings  204  disposed in an insulative housing  205  of the connector  201 . The connector  201  is shown in its eventual mounting location on the circuit board  202  and the connector housing  205  illustrates in this embodiment includes a pair of card edge connector portions  206  which are disposed in a “stacked”, or vertically spaced-apart, fashion along the front face  207  of the connector housing  205 . The stacked connectors  201  are enclosed within a metal shielding cage assembly  220  that has two module-receiving bays  221  defined therein. Each of these bays  221  is intended to receive an electronic module  222  therein in a fashion that is well known in the art. The module-receiving bays  221  are also stacked or spaced-apart vertically from each other and, due to the cage construction, an intervening space  223  that extends lengthwise through the shielding assembly  220  is defined between the two bays  221 .  
      The light pipe assembly  200  includes two pairs  210  of light pipes  212  that extend forwardly of the connector  201  along the sides of the connector housing  205  and into the intervening space  223  between the two bays. The light pipes  212  are generally L-shaped and have first ends  214  ( FIG. 10 ) that are positioned in opposition to illuminators  225  located on the circuit board  202 . The second ends  215  of the light pipes are located on the opposite ends of the light pipes  212  and as illustrated, are preferably held in place and in a selected alignment by an end cap  216 , which typically would be formed of a conductive material. This is so that the end cap  216  may provide a means of electrically connecting the two module-receiving bays of the shielding assembly together as well as providing a measure of electromagnetic interference shielding across the intervening space in which it resides. The exterior shielding cage assembly includes a rear wall  250  that may be formed as a separate piece or may be formed as part of the top cage assembly. In the former instance, the rear wall  250  is separately attached to the cage assembly and in the latter instance, it is preferably folded down over the back opening of the cage assembly and then attached to the upper cover  251 . Instances where the rear wall  250  is formed as part of the upper cover  251 , it is attached thereto along and end  252  and then folded back over the rear opening. In either instance, the rear wall  250  is preferably secured by integrated clips  254  or pins or the like.  
      The end cap  216  is received within (as are the horizontal portions of the light pipes  215 ) the intervening space  223  that separates the two bays  221 . The end cap  216  may include indicia  217  that identify the function of the connector  200 , i.e., whether the modules are connected to the connector or whether the modules are energized or the like. As shown best in  FIG. 11 , the end cap  216  may include a plurality of engagement members, shown as raised members  218  that engage opposing elements formed on the top bay  221  of the shielding assembly  220 . Slots  219  may be formed in the members  218  to receive members  225  formed in the top bay  221 . ( FIG. 9 .) Similarly, the square, raised member  218  may be received in a like-sized opening  226  that is disposed in the upper cage assembly  220 . Each pair  210  of light pipes may further include a support bar  230 , shown vertically, that may be integrally formed with the pair  210  of pipes in order to space the pipes of each pair  210  apart a selected distance. In order to engage the connector and to partially support the pipes in their extent, the pairs of light pipes may further each preferably include engagement members  232 , shown as hook-type lugs that extend inwardly of the pipe pairs  210 . As shown best in  FIG. 16 , these lugs  232  are received within cavities, or slots  209  that are formed in the front face of the connector housing  205 . As shown in the Figures, the lugs  232  are L-shaped, but any configuration that holds the pipes in place will suffice.  
      As shown best in  FIG. 13 , the light pipes may have thick body portions  235  that reduce down in thickness to thin second end portions  236 . These end portions  236  are received within complimentary openings  237  formed in the end caps  216  and which extend lengthwise through the end cap  216 . In this regard, the end cap  216  may keep the pipes together in a selected alignment along their lengthwise extent through the intervening space  223  between the two module-receiving bays  221  of the shielding assembly  220 . As shown best in  FIGS. 17A &amp; 17B , the connector housing  205  has recesses  208  formed along the sidewalls of the connector housing  205 , and the recesses are shown as positioned generally on the connector housing  205  at a level midway of the height of the connector housing  205 , but the recesses may be located elsewhere.  
       FIG. 18  illustrates another connector assembly that incorporates light pipes constructed in accordance with the principles of the present invention. In  FIG. 18 , only the shield assembly  301  is illustrated along with the circuit board  302  and the light pipe end cap  304 . In assembly, the shield assembly  301  receives the connector housing  205  from the rear opening and then the rear wall member  314  is applied to the shield assembly  301  so as to form an integrated assembly that is applied to the circuit board  302  as a single element, rather than applied over a discrete connector applied to the circuit board. The shield assembly  301  is configured to define a pair of module-receiving bays  305  that are spaced apart from each other in the vertical direction so as to be considered stacked upon each other. The bays  305  are separated by an intervening space  306  that is shown occupied by the end cap  304  and through which the light pipes extend. The shielding assembly  301  is shown as including a hollow enclosure  310  that has a bottom wall  311 , intervening walls  312 ,  313  and a rear wall  314  that closes off the enclosure after the connector and light pipe assemblies have been inserted as a unit from the rear of the shielding assembly  301 . The intervening walls  312 ,  313  have tabs  315  that extend into and preferably through openings  317  that are formed in the side walls of the enclosure  310 .  
      In  FIG. 19 , the shielding assembly  301  is removed from the circuit board  302  for clarity in order to expose the internal connector  320  and the light pipe assembly  330  to view. The connector component  320  includes an insulative housing  321  with two edge card-receiving slots  322  spaced vertically apart from each other so that each slot  322  is aligned with one of the two module-receiving bays  305 . The connector housing  321  includes a plurality of cavities, each of which receives a single conductive terminal  324  therein. As is known in the art, each terminal may include a contact portion that is exposed within the card slots  322 . A light pipe assembly  330  is shown with two pairs of light pipes  331  which are separated from each other horizontally. These pipes have indicator ends  332  received within an end cap  304 , which includes openings  333  which communicate to the pipe indicator ends  332 .  
      As shown best in  FIG. 21 , the light pipe assembly  330  preferably includes two distinct elements, which may be referred to as first and second arrays  336   a ,  336   b  of light pipes. Each such array  336   a ,  336   b  includes two light pipes  331  that are spaced apart from each other. The spacing between the two pipes is closer in the first array  336   a  than it is the second array  336   b . ( FIG. 22 .) In this manner the light pipes  331  of the first array  336   a  may be received within the space between the two pipes  331  of the second light pipe array  336   b . In such a fashion, the first array  336   a  may be considered as at least partially “nested” within the second array  336   a.    
      Similar to the other embodiments, the two light pipes  331  of each array  336   a ,  336   b  are held together in their spacing by a support or tie bar  337   a ,  337   b  which extends horizontally somewhat above the light pipes  331  of the first array  336   a  and somewhat underneath the light pipes  331  of the second array  336   b . The light pipes are generally L-shaped and have opposing ends  338 ,  339 , with one end  338  being positioned over or on a illuminator device  345  disposed in the circuit board  302  near the sides of the connector  320 . With the support bars  337   a ,  337   b  of the light pipe arrays  336   a,b  being inverted, it is possible to place the first array  336   a  of pipes on and within the second array  336   b  of pipes. The support bars  337   b  of the second light pipe array  336   b  in effect, define a “nest” into which the horizontal extent of the first light pipe array  336   a  are received. This nesting is shown best in  FIGS. 23A, 26A  &amp;  26 B.  
      The rearmost support bars  337   a ,  337   b  of each of the light pipe arrays  336   a, b  include means for engaging the connector  320  and such means are illustrated as pairs of engagement hooks  339  that extend rearwardly from their support bars  337   a ,  337   b . These hooks  339 A are received within recesses  340  that are formed in the connector housing  321  and which, as shown best in  FIG. 23B , include shoulder portions  341  which the engagement hooks  339 A engage. The engagement hooks  339 A of the first array  336   a  are received in the top row of recesses  340  as shown in the sectional view of  FIG. 23B , and the engagement hooks  339  of the second array  336   b  are received within the bottom row of recesses  340 . ( FIG. 20 .)  
      The offset nature of the support bars  337 ,  338   a,b  also facilitates the fitting of the light pipes into the intervening space  306  between the top and bottom bays  305  by reducing the overall height of the horizontal extent of the light pipe arrays  336   a,b.  The end cap  304  may include slots  344  that are formed on the top and bottom surfaces thereof receive stubs  346  formed on the intervening walls of the shielding assembly  301 .  
       FIGS. 27 and 28  illustrate an embodiment  400  in which the light pipe assembly  401  is integrally formed as a single piece, such as by injection molding or any suitable process. In  FIG. 28  the light pipe assembly  401  has two pairs of light pipes  403  associated which are interconnected together by support members  405  to form a lattice-like structure. The support members  405  are shown interconnecting together both the vertical and horizontal portions of the light pipes. Another set of support members  407  may interconnect the horizontal portions and may include engagement members  409  formed therewith, which are received within corresponding openings  412  disposed in the front face  413  of the associated connector component  420 . The forwardmost support member  405  may also include an engagement member, shown as a hook member  423  that engages the shoulder  430  of an end cap  431 . Once again in this embodiment, the light pipe assembly  401  is supported entirely along the front face  413  of the connector  420  and not by any side portions thereof, which assists in reducing the overall width of the connector assembly and exterior shielding assembly (not shown).  
       FIG. 29  illustrates a connector  500  suitable for use in small form factor applications and particularly with the aforementioned light pipe assemblies, and which is constructed in accordance with the principles of the present invention. The connector  500  includes a housing  502  that is preferably formed from an insulative material, which may be injection molded or the like. The housing  502  has a forward engagement portion  504  with a frontal face  506 . The forward engagement portion extends forwardly into the interior space of the exterior shielding assembly. The housing illustrated includes a base portion  508  and a top portion  510 . The base and top portions  508 ,  510  extend rearwardly from the forward engagement portion  504  and cooperatively define what may be considered as an internal cavity  511  of the connector that opens to the rear of the connector. ( FIG. 31 .) The base portion  508  is intended for mounting to a circuit board (not shown) and therefore may preferably include mounting members, like posts  509  and stabilizing lugs  507  extending out from the connector housing sides laterally so the bottom surfaces thereof may abut the circuit board.  
      The housing internal cavity  511  houses a plurality of terminal assemblies  520 , one of which is illustrated best in  FIG. 33 . As shown in  FIG. 33 , the terminal assembly  520  includes a plurality of conductive terminals, shown as two sets of pairs  531  of terminals. The terminals  521   a ,  521   b  of each pair  531  are spaced apart from each other vertically (shown by line X 1  in  FIG. 33A ), and the two pairs themselves are likewise spaced apart from each other in the vertical direction (shown by line X 2  in  FIG. 33A ). This spacing permits the terminal assemblies  520  to be used in connector  500  of the present invention which are suited for stacked or dual configuration in accordance with small form-factor connector specifications. The terminals pairs  521  of the assembly  520  are further offset from each other. This is shown best in the front elevational view of  FIG. 33B , where it can be seen that the terminals  521   a ,  521   b  of each pair  531  of terminals in the assembly frame are offset from each other in the vertical direction.  
      The terminals  521  are initially supported in a lead frame and then are inserted into a mold where the terminals  521  are separated from the lead frame as is known in the art, and a supporting dielectric frame  522  is molded over portions of the terminals  521 , such as by over molding. The dielectric frame  522  provides a measure of thickness to the terminal assembly  520  and defines a body portion of the assembly. The terminals are trimmed into separate terminals by a process known in the art. The terminals are preferably arranged in an inverted-L configuration as shown so as to maintain the depth of the connector at an optimum amount and so as to accommodate the clips  535 .  
      The terminal assembly  520  preferably has a generally square or rectangular configuration, as shown, with four distinct sides. The terminals  521 , as shown best in  FIG. 34 , include contact portions  523  that extend along one side  524  of the assembly  520  and tail portions, shown as compliant pin portions  525 , that extend along and out from another side  526  of the terminal assembly  520 . These two sides  524 ,  525  are adjacent each other as shown, although other configurations are suitable. The terminals  521  further include body portions  527  that interconnect the contact portions  523  and the tail portions  525  together and the overall configuration of the terminals  521  of the assembly  520  may be considered is L-shaped. The dielectric frame  522  may include, as best shown in  FIG. 33 , openings  528  that follow the path of the terminals  521 , with sets of openings  528  tracking single terminals. These openings  528  expose portions of the terminals  521  to air and are suitable for providing an air-terminal interface between selected portions of terminals of the connector. This exposure to air may be used for affecting the impedance of the system in which the connector  500  is used, and particularly the impedance of the terminals  521  of the terminal assemblies  520 .  
      The openings  528  are offset from each other on the opposite sides of the terminal assembly  520 . This is best illustrated in  FIG. 33C , where a pair of terminal assemblies  520  are shown opened aprt from each other, in the manner of pages of a book. The rear edges  5280  and the bottom edges  526  are aligned with each other to illustrate the offset. As mentioned above, the dielectric frames  522  of the terminal assemblies have openings  528  formed therein which track the path of the terminals  521  in their extent through the frame  522 . The openings  528 , preferably take the form of slots as shown and cross bars  529  are provided as part of the frame  522  to provide strength to the frame. In order to provide a complete air channel that traces the path of pairs of terminals of adjacent terminal assembly frames  522 , the cross bars  529  are located in one position on the left side of the terminal assembly and located in different positions on the right side of the terminal assembly  520 . This offset in the vertical direction is shown for the horizontal cross bars in  FIG. 33C  as “O 1 ”. This offset in the horizontal directions for two of the vertical cross bars is shown in  FIG. 33C  as “O 2 ” and “O 3 ”. An examination of the two facing sides of the terminal assemblies of  FIG. 33C  shows that all such cross bars  529  are offset. Thus, an air channel (“AC”) or pathway is defined that begins at approximately “AA” and ends approximately at location “BB” on the terminal assemblies as shown in  FIG. 33C . As can be seen in the detail view of  FIG. 33D , the offset of the cross bars  529  permits unimpeded flow of air through the air channel AC.  
      The rear edge, or side  5280  of the terminal assemblies  520  may include notches  530 , or other suitable openings which may receive a transverse alignment bar (not shown) for maintaining the rear sides  5280  of the terminal assemblies  520  together in alignment as a single group. The plastic frame  522  of the assemblies also includes support portions  532  associated with each pair  531  of terminals  521 . These support portions  532  provide not only a base in which to embed the terminal contact portions  523  and space them apart in the offset manner shown in  FIG. 33B , but they also serve as an means for aligning or interlocking the terminal assemblies  520 , especially the contact portions  523  thereof together. In this regard, the support portions  532  are preferably formed with notches  533  and projections or tabs  534  in a complementary fashion, so that as illustrated in  FIG. 33B , the support portions engage or interlock with each other to hold the upper terminals  521   a  of each pair in alignment with each other in a horizontal plane as well as the lower terminals  521   b  of each pair of terminals  521  in their own horizontal plane. Preferably, the horizontal planes in which the upper and lower terminals  521   a ,  521   b  respectively lie are arranged parallel to each other.  
      Preferably, the connectors of the present invention utilize differential signaling in their operation and the differential pairs of terminals utilize broadside capacitive coupling rather then edge coupling. As such, the differential signal pairs of terminals are arranged in a row along the upper and lower terminals  521   a ,  521   b . Four such differential signal terminal pairs are illustrated in  FIG. 33B . In this regard, the support portions  532  also preferably hold the terminals  521   a ,  521   b  of each terminal pair in position so that the spacing DP 1  between differential signal pairs of terminals of two adjacent terminal assemblies  520  is maintained. The support portions  532  also provide support during the insertion of the terminal assemblies  520  into the connector housing.  
      In another important aspect of the invention, and as best illustrated in  FIGS. 33 and 34 , each terminal assembly  520  is preferably provided with means for engaging the connector housing  502 , and this engagement means is illustrated in the drawings as an elongated clip member  535  that is disposed along one side, namely, the front side  524  of the terminal assembly  520 . This clip member  535  is disposed between the two sets of terminal contact portions  523  and it also extends forwardly of the terminal assembly frame  522  in order to contact an opposing ledge  537  or similar engagement member that is disposed in the connector housing  502 . This engagement member is shown best in  FIG. 35  in the form of a shoulder, or bar,  537  that extends horizontally as shown and which projects rearwardly in the internal cavity  511  of the connector housing  502 . As shown best in  FIG. 32 , the shoulder is preferably provided with a plurality of slots  539  ( FIG. 31 ) that are spaced apart from each other widthwise of the connector housing  502 , and which extend lengthwise within the connector housing  502  toward the front of the connector  500 . Each clip member  535  preferably includes a pair of free ends  540  that are spaced apart (shown in the vertical direction) to define a small bight therebetween, which preferably is less that the thickness of the bar  537  so the clips  535  may engage the bar  537  reliably and exert a positive retention force thereon.  
      The terminal contact portions  523  likewise may be received within corresponding terminal-receiving slots  542  that are formed in the connector housing  502  and which are typically disposed on opposite sides (top and bottom) of the card-receiving slots  505 . ( FIG. 36 .) The terminal assembly engagement clip members  535  are preferably formed from a durable metal that is strong enough to maintain a reliable grip on the opposing shoulder  537  of the connector  500 . The clip member  535  may be easily molded as an insert into the dielectric frame  522  of the terminal assembly  520 , and as illustrated in  FIG. 34 , may include a wide body portion  545  with an opening  546  formed therein to improve the retention of the clip  535  in the frame  522 . The clip members  535  provide a third point of engagement with the connector housing  502 , with the first two points of retention being the two sets of the terminal contact portions  523  which are retained within their corresponding terminal-receiving slots  542 .  
      Turning now to  FIG. 36 , the connector  500  is seen in frontal elevation, which best illustrates the number of engagement portions that are disposed on the connector housing  502  and arranged on the front face  506  thereof. As described above, the connector housing  502  may include openings  340  formed therein that receive the engagement hooks  339  of the light pipe arrays  336   a,b.  These openings  340  are preferably disposed on the connector front face  506  in the area between the two card edge-receiving slots  505  of the connector  500 , and further preferably are disposed in between the shielding assembly engagement openings  550 .  
      An additional set of openings  550  ( FIG. 38 ) are disposed on the front face  506  and these openings extend horizontally within the connector housing  502 . These openings receive engagement members, in the form of tabs or lugs  552  of the portion of the exterior shielding assembly that defines an intervening wall between the two module-receiving bays of the shielding assembly. This is shown best in  FIGS. 35 and 40 . These slots  550  extend rearwardly in the housing  502  and include an inner ledge  551 . This inner ledge  551  provides a shoulder for a tang  553  on the shielding assembly engagement tabs  552  to bear against and retain the shield in place and in alignment with the connector housing  502 . Both these openings  550  and the light pipe engagement openings  340 . In this manner, the light pipes and the shielding assembly all engage the connector housing  502  in a secure manner so that all of the components will act as a single assembly. In this manner, the light pipes and connector may be assembled as a unit and inserted into the shielding assembly from its rear.  
      The base portion  508  of the connector housing  502  has an opening that communicates with the internal cavity  511  of the housing  502 . This permits the bottom edges  526  of the terminal assemblies  520  to lie flat on the surface of the circuit board, if desired and as shown best in  FIG. 35 .  
      While the preferred embodiment of the invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the invention, the scope of which is defined by the appended claims