Patent Publication Number: US-7585188-B2

Title: Edge card connector assembly with high-speed terminals

Description:
REFERENCE TO RELATED APPLICATION 
   This application claims priority for prior U.S. Provisional Patent Application No. 60/586,126, filed Jul. 7, 2004. 

   BACKGROUND OF THE INVENTION 
   The present invention is directed generally to edge card connectors and, more specifically to edge card connectors in which the connector impedance may be controlled by shaping of the connector terminals. 
   High speed data transfer systems require electrical connectors in which the electrical impedance can be controlled in order to maintain the required data transfer rate of the electrical system. It is desirable at high speed data transfer rates to obtain a specific impedance in a connector that matches the impedance of the entire electronic system, i.e., the circuits on the a circuit board of an electronic device and either the circuits of opposing electronic device or in a transmission cable. The impedance of a connector may be controlled by the spacing of the terminals, the size of the terminals and the thickness and location of material within the connector housing. 
   However, low profile connectors, such as those used in SFP (Small Form Factor Pluggable) and SFP-like applications are desired in electronic devices in which space is a premium and thus it is difficult to control the impedance by modifying the spacing and size of the terminals in a reduced-size connector housing. When the structure of the terminals are modified, it becomes difficult to retain all of the mechanical functions of the connector, such as terminal retention and engagement while tuning the impedance of the connector 
   The present invention is directed to an improved electrical connector system that combines the aforementioned characteristics and which provides terminals that are capable of accommodating high data transfer speeds of approximately 2 gigabits per per second and greater. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is a general object of the present invention to provide a low profile connector in which the terminals may have varying shapes for controlling the impedance of the connector. 
   Another object of the present invention to provide a surface mount style connector for mounting on a circuit board, the connector having a plurality of conductive terminals supported therein in spaced apart order, the terminals having stubs and slots formed as part thereof, thereby reducing and/or increasing the amount of metal to influence the capacitance and/or the inductance of the terminals and control the impedance thereof. 
   A further object of the present invention is to provide a right angle, low profile surface mount connector for use in high speed applications in which the connectors have a specific structure for controlling the impedance and inductance of electrical connectors. 
   A still further object of the present invention is to provide a small form factor connector for receiving the edge of a circuit card therein and providing a connection between circuits on the circuit card and circuits on a larger circuit boards, the connector having an insulative housing having a slot disposed therein for receiving the edge of the circuit card therein, and the housing further having two terminal insertion faces disposed therein, each of the faces including a plurality of terminal-receiving slots, the terminal-receiving slots being disposed on opposite sides of the connector to facilitate insertion of the terminals therein. 
   Yet another object of the present invention is to provide a high speed connector of small form factor having an insulative housing and terminals supported by the housing along two opposing surfaces of the housing, each of the terminal including a contact portion that extends in a forward direction of the connector housing and a tail portion that extends in a rearward direction of the connector housing, each of the terminals further including a retention portion disposed intermediate the contact and tail portions thereof, the retention portion being received within individual retention cavities that extend transversely to the card-receiving slot. 
   Another object of the present invention is to provide a high speed connector having an insulative housing with defined top, bottom and side surfaces, the connector housing accommodating a plurality of conductive terminals that are inserted into terminal-receiving cavities disposed in the top and bottom surfaces of the connector housing, the bottom surface of the connector housing being recessed to define a recess between it and a top surface of a circuit board to which the connector housing may be mounted, the recess being sized sufficiently to receive a projection from an opposing mating connector to thereby provide a means for ensuring proper engagement between the connector housing and the opposing mating connector. 
   Yet a further object of the present invention is to provide a small size connector suitable for use in small form factor applications, the connector including a housing that supports a plurality of conductive terminals that are arranged in two distinct terminal sets on opposite surfaces of the connector, the terminal including surface mount feet that extend outwardly from the connector housing proximate a rear portion thereof, the terminal feet of one terminal set extending out from a first base portion of the connector housing and the terminal feet of another distinct terminal set extending out from a second base portion of the connector housing. 
   Still a further object of the present invention is to provide a small size connector for use in high speed data transmission applications, the connector having a slot for receiving a circuit card or a male portion of an opposing connector therein, the slot being flanked by a plurality of conductive terminals, each of the terminals including a retention member in the form of a stub that extends perpendicular to a body portion of the terminal, the stubs being sized to increase or decrease capacitance between adjacent terminals in order to firstly tune the impedance of the connector, the terminals being arranged in two distinct sets of terminals, one set of the terminals having their tail portions substantially disposed in the insulative housing of the connector and the other set of terminal having their tail portions substantially disposed in air, thereby creating two different sets of dielectric material that encompasses the terminal to secondly or further tune the impedance of the connector. 
   The present invention accomplishes the aforementioned and other objects by the way of its novel and unique structure. In one embodiment of the invention, a connector assembly is provided for mounting to a circuit board with surface mount technology. The connector includes a dielectric housing and terminals of a first type which are stamped from a metal strip and are inserted into slots in a front face of the connector housing. Terminals of a second type are stamped from a second metal strip and are inserted into slots along the rear face of the connector housing so the first and second type terminals are opposing each other. The first and second sets of terminals are inserted into the connector housing along two distinct faces of the housing, which are preferably on opposite ends, or sides of the housing. 
   The first and second type terminals have cantilevered contact arm portions that at least partially extend into an internal receptacle of the connector housing which is designed to receive the edge of a circuit card. Both the first and second types of terminals have contact portions, tail portions and interconnecting body portions. The terminal body portions also include terminal retention portions that are press fit into slots, or other cavities, that are formed in the connector housing. The terminals are inserted into the connector housing from two opposite sides of the housing, preferably the top and bottom sides of the housing. Using this connector housing structure, the terminal may be reduced in size, yet still maintain their overall cantilevered configuration. The tail portions of the terminals of this embodiment include surface mount feet that preferably extend at an angle so that they are oriented parallel to the circuit board. The terminals may also include through hole tails that extend at an angle to the circuit board. 
   Each terminal include a contact portion and a body portion that extends between the contact and tail portions. The terminals are received in terminal-receiving cavities that extend lengthwise through the connector housing in a staggered arrangement so that the terminals of one of the two distinct terminal sets are staggered with respect to the other of the two distinct terminal sets. The terminal body portions further include retention portions that preferably take the form of stubs that extend out at an angle to the body portions and the stubs are received within slots that extend at an angle, preferably inwardly of the connector housing, to the main terminal-receiving cavities of the connector housing. 
   The connector housing of the invention may include two distinct base portions which are spaced lengthwise apart from each other. Each of these base portions preferably supports a single set of terminals near the tail portions thereof. With this arrangement, the bottom of the connector housing may be hollowed out to form a recess that opens to the front of the connector and which is closed of by one of the two base portions at the rear of the recess. This recess is configured to receive a projection from an opposing mating connector in the form of a plug connector. This recess permits a user to ensure that the opposing mating connector will be properly inserted into and mated with the connectors of the invention. This recess does not reduce the overall structural integrity of the connectors of the invention and the location of the slots that receive the retention members also does not reduce the structural integrity of the connectors of the invention. 
   The two distinct base portions serve to locate the tails of the two sets of terminals in different locations. The tails of one set of terminals are positioned inwardly of a rear edge of the connector housing , while the tails of the other set of terminals are positioned proximate to the rear edge of the connector housing. The tails of the one terminal set are substantially enclosed with the material that makes up the connector housing while the tails of the other terminal set are supported mostly in air, thereby providing two different dielectric materials that enclose the terminal tail portions to thereby tune the impedance of the connector along the tail portion area thereof. 
   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 
     In the course of this detailed description, the reference will be frequently made to the attached drawings in which: 
       FIG. 1  is an exploded perspective view of a known connector assembly illustrating one type of circuit board application to which the present invention is directed; 
       FIG. 2  is a cross-sectional view of the connector assembly of  FIG. 1  taken along line  2 - 2  thereof, removed from the circuit board and illustrating the housing, its mating slot and the positioning of first and second terminals therein; 
       FIG. 3  is a cross-sectional view of a known connector housing; 
       FIG. 4  is a side elevational view of a first type terminal utilized in the known connector assembly of  FIG. 1 ; 
       FIG. 5  is a side elevational view of a second type terminal utilized in the known connector housing of  FIG. 3 ; 
       FIG. 6  is a side elevational view of another style of a second type terminal suitable used in the known connector housing of  FIG. 3 , illustrating another modification of only a single terminal body portion to reduce the overall surface area thereof; 
       FIG. 7  is a perspective view of the connector housing of  FIG. 3 , angled to show the rear face thereof and having the second terminals of  FIG. 5  inserted therein; 
       FIG. 8  is a cross-sectional view of the connector housing of  FIG. 3 , with a second terminal as shown in  FIG. 6 , inserted in place within the rear face of the housing; 
       FIG. 9  is a cross-sectional view of the connector housing of  FIG. 3 , with a first terminal as shown in  FIG. 4  and a second terminal as shown in  FIG. 5  inserted therein; 
       FIG. 10  is a perspective view of a new connector constructed in accordance with the principles of the present invention; 
       FIG. 11  is an exploded view of the connector of  FIG. 10 ; 
       FIG. 12  is a top plan view of the connector of  FIG. 10 ; 
       FIG. 13  is a front elevational view of the connector of  FIG. 10 ; 
       FIG. 14  is a cross-sectional view of the connector of  FIG. 10  taken along a line that exposes to view one terminal of the top terminal set of the connector and illustrating its manner of engagement with the connector housing; 
       FIG. 15  is a cross-sectional view of the connector of  FIG. 10  taken along a line that exposes to view one terminal of the bottom terminal set of the connector and illustrating its manner of engagement with the connector housing; 
       FIG. 16  is a staggered cross-sectional view of the connector of  FIG. 10  taken along a line that exposes to view one terminal of each of the top and bottom terminal sets of the connector and illustrating their manner of engagement with the connector housing; and, 
       FIG. 17  is a cross-sectional view of an alternate embodiment of a high speed SFP-style connector which has terminal configurations that are best suited for through hole mounting applications. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  illustrates a known connector assembly, generally designated as  1 , that will be used to explain the environment in which the present invention operates. The connector assembly  1  is a surface-mount style and is intended for mounting to a printed circuit board  2 . The connector assembly includes an insulative housing  3 , preferably formed from a dielectric material, and a plurality of conductive terminals  19  are supported in the housing  3 . The terminals  19  are arranged in two distinct sets of first terminals  4  and second terminals  5 . The connector housing preferably has a configuration which includes a plurality of distinct faces and these faces include a first, or front face  6  and an opposing second, or rear face,  7 . Side faces or sidewalls  8 ,  9  are seen to interconnect the front and rear faces  6 ,  7  of the housing together, and in the embodiment illustrated, the housing. The first face  6  of the connector housing may be considered as a mating face of the connector inasmuch as it contains a slot formed therein for receiving an edge of a circuit board or edge card therein, and the second face  7  of the connector housing may be considered as a mounting face inasmuch as a portion of the connector, by way of the rear terminals, is mounted to the circuit board  2 . 
   The first terminals  4  are mounted into slots  71  formed in the connector housing  3  along its front face  6 , while the second terminals  5  are mounted in slots  72  that are formed in the connector housing  3  along its rear face  7 . The front and rear faces  6 ,  7  are oriented substantially perpendicular to the printed circuit board  2  onto which the connector housing  3  is mounted. Mounting portions  20  formed in the terminals  19  are located on the terminals  19  in locations spaced away from the connector housing  3  and serve as a means for connecting the terminals of the connector to corresponding conductive pads  22  formed with the circuit board  2  in a surface mount manner. These mounting portions are illustrated as conventional surface mount tails. The connector housing  3  may also include mounting pegs, or posts  24  formed therewith that are received within complementary openings  26  formed with the circuit board  2 . 
     FIG. 2  illustrates, in cross-section, the connector housing  3  of  FIG. 1 . This view shows the position of the two sets of terminals  4 ,  5 . The connector housing  3  includes an internal cavity, or receptacle  30 , which receives an insertion edge  32  of an edge card  31 , illustrated in phantom. The two terminals  4 ,  5  each have contact arm portions  72 ,  73  that extend in a cantilevered fashion, from body portions  87 ,  88 , into the internal receptacle  30  along opposite sides thereof in opposition to circuit pads  33  arranged on the circuit card  31 . The terminals  4 ,  5  may also include terminal retention portions  8 ,  88  &amp;  89  which may or may not form part of the terminal body portions. These retention portions include one or more teeth or barbs,  81 , that skive, or cut, into the connector housing material along the edges of the three retention slots  90  which are shown in the Figure. 
     FIG. 4  illustrates, a first type of terminal  100  that is used in the known connectors of  FIG. 3 . This terminal  100  is seen to have a surface mount portion  22 , an elongated, cantilevered contact portion  72  that extends into a card-receiving slot of the connector, a body portion  87 , and a terminal retention portion  8  that is received within a slot or cavity formed in the connector housing. Barbs  81  are provided as part of the terminal retention portion  8  to increase the retention of the terminal in the connector housing. 
     FIG. 5  illustrates a terminal  101  used in the second set (or type) of terminals in connectors of the present invention. The terminal  101  includes an elongated, cantilevered contact portion  91 , a first (upper) retention section  92  that is also considered to be part of a terminal body portion  93 . A second (lower) retention section  94  is also provided and is spaced apart from the first retention section  92 . Both retention sections  92 ,  94  are disposed on the terminal  101  between the contact portion  91  and the mounting, or tail portion,  97 . 
   The first retention portion  92  includes a relatively large central part  98 , which has an opening  95  formed therein. This opening is shown as circular and completely enclosed within the terminal retention area and serves to reduce the metal of the terminal and this particular portion thereof and it also reduces the capacitance of the terminal with respect to any adjoining terminal, by reducing the amount of surface area of the terminal. This reduction of material also increases the inductance of the terminal, which also influences the impedance of the terminal. The reduction of capacitance (or increase in inductance) will in turn, as is known, affect the impedance of the terminal, and of the connector overall in the region from the second terminal contact portion  91  to the mounting portion  97  thereof. The second terminal retention portion  94  also has an opening  96  formed therein and this opening  96  takes the form of a slot that preferably extends from an edge and through a portion of the central area of the second terminal retention portion  94 . This slot  96  is not completely enclosed in the retention portion  94  as in the top retention portion. The opening  95  is shown as circular, a variety of other shapes, preferably polygon shapes may be used. The size and shape of this first retention portion  92  may be varied in order to vary the impedance of the system. 
     FIG. 6  illustrates another second-type terminal, where the terminal  102  contains a contact section  15 , a single retention section  16 , and a board mounting section  17 . The retention section  16  of this second terminal  102  also contains an opening  18  therein in which metal has been removed from the stamped terminal  102 . In the illustrated embodiment, this central portion is substantially circular, but can also take a variety of shapes. The size and shape of this central portion can be varied in order to vary the impedance of the system. The retention section of the second terminal may contain barbs  19  which are used to embed in the slots of the dielectric housing to provide terminal retention. The size of the board mounting portion  17  may also be varied to provide adequate area for mounting to the printed circuit board, while also being tuned to provide a specific impedance in the terminal. 
   The terminals are easily stamped from sheet metal, but because of the openings  95 ,  96  formed thereon, a concern is raised about the ability to retain the second terminals  101 ,  102  within the connector housing  3 . This concern is alleviated by modifying the connector housing  3 ′, as illustrated in  FIG. 3 , in order to provide additional housing material  66 ′,  67 ′ and  68 ′ near the retention slots  90 ′. The effect of this additional material is shown in  FIGS. 8 &amp; 9 , where the material  66 ′ and  67 ′ enclose and abut the enlarged terminal first retention portion  92  and in effect, provide additional reaction surfaces against which the retention portions  92 ,  94  bear.  FIG. 9  illustrates how the other second terminal of  FIG. 3  is fit into the housings  3 ′ of the invention. 
   The length and width of the second retention portion can also be varied in order to vary the surface area of the terminal, and therefore also the impedance. Both first and second retention sections of the second terminal may contain barbs, or teeth  51  which are used to embed the terminals  101  firmly and reliably within the slots  72  of the connector housing  3 . The size of the board mounting section may also be varied to provide adequate area for mounting to the printed circuit board, while also being tuned to provide a specific impedance in the terminal.  FIG. 7  illustrates the rear face of the connector housing, where each of the terminal receiving slots  72  include a pair of opposing retention bumps  21  disposed on opposite sides of the terminal, for increased terminal retention to the housing. 
     FIGS. 10-16  illustrate an embodiment of a connector constructed in accordance with the principles of the present invention. In this embodiment, the terminal configuration and arrangement may high speed data signals at speeds of at least approximately 2 gigabits per second and greater up to at least 10 gigabits per second and beyond. It has been found in other connectors, especially those known connectors as exemplified in  FIG. 2 , that certain structural elements adversely affect the ability to carry high speed signals. Mostly, it is due to at least one of the connector terminals, and such a terminal is shown by the first or front terminal  4 . The large surface mount portion  20  thereof adds inductance to the overall impedance of such a connector and thus the terminal  4  must act as a low speed terminal. 
   The connectors of the present invention provide the ability to carry high speed data signals of 2 Gbps and greater and approaching approximately 10 GBps. As illustrated in  FIG. 10 , the connector  200  includes a housing  201  that has a top  202 , a bottom  203  and two sides  204 ,  205 . The bottom  203  may include one or more mounting posts  206  that are used to position the connector on a circuit board (not shown). The front of the connector preferably includes a circuit card-receiving slot  210  that receives the leading edge of a circuit card that is typically housed within an electronic module (not shown). As shown in  FIGS. 14-16 , this slot  210  extends interior of the connector housing  201  and is bounded by a top wall  211 , a bottom wall  212 , a rear wall  213  and two side walls  214 ,  215 . ( FIG. 13 .) 
   The connector  200  includes two distinct sets of thin conductive terminals  220 ,  221  that extend into the card-receiving slot  210  and which provide an electrical transmission path from circuits on the circuit card to circuits on the larger circuit board. The sets of terminals are similar in that they each include contact portions  225  that extend into the card-receiving slot  210  and tail portions  226  that extend out of the connector housing  201  in opposition to the circuit board to which the connector  200  is mounted. The terminals also include what may be considered as body portions  227  that are disposed intermediate the contact and tail portions  225 ,  226  and which interconnect them together. For purposes of understanding the structure of the present invention, the body portions  227  are considered to end just after where the terminal retention portions extend away from the terminal body portions. The mounting or tail portions of the terminals begin at the same location. This is shown diagrammatically in  FIGS. 14 &amp; 15 , wherein “B” is represents the end of extent of the terminal body portions and “M” represents the beginning of the extent of the mounting or tail portions of the terminals. 
   The terminals of the first, or top set,  220  of terminals are inserted into the connector housing  210  in slots  230  that are formed in the top wall  211  of the housing  201 . As shown best in  FIG. 14 , these top slots include openings  231  that communicate with the card-receiving slot  210  of the housing  201  and are positioned so that the contact portions  225  of the top terminal set  220  may at least partially extend into the slot  210 . The terminals of the second, or bottom set  221  of terminals are inserted into the connector housing  210  in slots  235  that are formed in the bottom wall  211  of the connector housing  201 . As shown best in  FIG. 15 , these bottom slots  235  include openings  231  that communicate with the card-receiving slot  210  of the housing  201  and are positioned so that the contact portions  225  of the top terminal set  220  may at least partially extend into the slot  210 . The terminal-receiving slots  230 ,  235 , as best illustrated in  FIG. 13 , are offset from each other so that the slots  235  that hold the bottom set of terminals  221  are preferably arranged so that they are positioned offset from the terminals  220  that occupy the top set of slots  230 . In this fashion, a triangular arrangement of groups of terminals may be effected, with three terminals being positioned at respective apexes of an imaginary triangle. Such an arrangement is shown in phantom lines in  FIG. 13  at “TR” and. it is preferably used in differential signal applications with a pair of differential signal terminals (i.e., two terminals carrying the same magnitude voltage signal, but of different polarities, such as +0.5 volts and −0.5 volts) and an associated ground terminal. 
   The terminals each further preferably include retention portions  229  (shown as stubs) that primarily serve to retain the terminals in place within the connector housing  201 . As illustrated, these terminal retention portions  229  extend at an angle away from the body portions of the terminals and into additional cavities  240  that are formed in the housing  201 , and which may be formed, as shown, in the rear wall  212  of the connector housing  201 . These additional cavities are offset as between the top and bottom sets  220 ,  221  of terminals, so that the retention portions  229  of the two terminal sets  220 ,  221  that are received therein extend toward each other. The free ends  229   a  of the retention portions are preferably spaced from each other a preselected distance so as to obtain a desired capacitive coupling therebetween. 
   These retention portions  229  support the terminals  220 ,  221  in a cantilevered fashion, and the terminal slots  210 ,  211  may be provided with angled faces  241 ,  242  that extend toward the card-receiving slot  210  and the slot openings  230 ,  235 . In this manner, the contact portions  225  of each of the terminals of the two terminal sets  220 ,  221  extends in a cantilevered fashion into the card-receiving slot  210 . These angled surfaces  241 ,  242  also serve as reaction surfaces against which the terminals  220 ,  221  may be bear if the terminal are stitched in the connector housing  201 , which would normally occur if the terminals tail portions were of the through hole type (as illustrated in phantom in  FIGS. 14-16 ). 
   In order to achieve a close terminal to terminal spacing within the card-receiving slot  210 , the bottom set  221  of terminals is preferably inserted from the bottom of the connector housing  201 . This is achieved without the connector housing losing any significant structural integrity. The main retention of the terminals  220 ,  221  occurs at the rear wall  212  of the connector housing card-receiving slot  210  and secondary retention is provided by the terminal slots  230 ,  235 . 
   Although terminal tail portions  226  of the surface mount type are described in detail herein, it will be understood that the connectors of the present invention may also utilize terminals having tail portions of the through hole type  236  as shown in phantom in  FIGS. 14-16 . Whatever the type of tail portions used for the terminals, it is desired to hold them in position with respect to each other. Rather than employ a separate tail alignment element, the present invention utilizes two different areas of the bottom side  203  of the connector housing  201  to hold the terminal tails  226  in place in a spaced-apart arrangement. The terminal tails  226  are spaced apart from each other lengthwise of the connector  200  and the tails  226 , as illustrated in the Figures, are spaced apart along two tail alignment or holding areas  245 ,  246 . 
   Also, as illustrated in  FIGS. 12 and 14 , the tail portions of the two sets of terminals are provided in two different dielectric mediums so as to further influence coupling between the terminals. As shown, the bottom set of terminals  221  have their tail portions enclosed within slots formed in the bottom of the connector housing. The effect of this is to provide a dielectric medium of the housing material between adjacent tail portions of those terminals. The tail portions of the top set of terminal  220  are seen to be substantially supported with only air as the dielectric medium between them. 
   As such, different coupling between the adjacent tail portions of the top and bottom terminal sets may be obtained, permitting the impedance of the connectors of the invention to be more finely tuned in the tail portion areas. The shorter length terminals, i.e., the bottom terminals, are enclosed in the plastic of the housing, while the longer length terminal, i.e., the top terminals, are enclosed air. This also permits the connector tail portions to be visually inspected during and after the connectors are soldered to a circuit board. Another impedance tuning aspect is obtained by the arrangement of the two sets of terminal tail portions. The vertical centerlines of the tail portions of the bottom set of terminals is spaced a first distance away (behind) from the vertical centerline of the bottom terminal retention portions and the vertical centerlines of the tail portions of the top terminals are spaced a second distance from the vertical centerline of the top terminal retention portions that is greater than the first distance. Typically, this second distance will be twice that of the first distance. 
   These areas include a plurality of tail slots  248 ,  249 , with one set of the slots  248  being arranged so that they face the front of the connector, and the other set of slots being arranged so that they face the rear of the connector  200 . The slots  248  also open to the bottom of the connector as shown best in  FIGS. 13 &amp; 15 , while the slots  249  open to the top of the connector as best shown in  FIGS. 12 &amp; 14 . It can be seen from  FIG. 16  that the terminals  220 ,  221  of the two terminal sets exhibit a measure of symmetry in that they are generally spaced-apart from each other a common distance along a center dividing axis shown in dashed line at X-X. Additionally, the retention portions  229  of each of the terminal sets  220 ,  221  extend toward each other and are of a small size, so that their stub nature does not create a large impedance discontinuity in this area of the connector terminals so that the impedance may be controlled along the extent of the terminals through the connector housing. The use of this symmetry permits the use of high speed terminals in an application that has size constraints. 
   It will be understood that the structure of the present invention provides unique advantages. The tail portions of the terminals near the bottom portion of the connector housing serve to anchor the terminals when an opposing mating blade or card is inserted into the connector. It can be seen that the tail portions of the top set of terminals will undergo compression as the free ends of the contact portions of the top terminals  220  are moved upwardly, causing a moment around the top terminal retention portions  229 . Similarly, insertion of a card or blade into the connector slot causes the contact portions of the bottom set of terminals to move downwardly, applying a moment around the bottom terminal retention portions  229 . This exerts a tensile force on the tail portions of the bottom set  221  of terminals. The application of these two different and opposing forces, reduces any concern that repeated insertions and removals of the mating connector will adversely apply any detrimental torsional forces to the terminal tail portions. 
   Turning now to  FIG. 17 , a through-hole embodiment  300  is illustrated in cross-section. As shown, this embodiment  300  has an insulative housing  301  with a card slot  302  that extends width wise across the face  303  of the connector housing  301 . Two sets of terminals  304 ,  305  are utilized and are inserted into the connector housing from the top and bottom surfaces thereof as in the connector  200 . The terminals have retention portions  306  that fit into cavities to retain the terminals in place and to provide a reaction surface for the cantilevered terminal contact portions  308 . The tail portions  309  of the terminals  394 ,  305  are angled and offset as shown to provide the through hole feature. A thin web of housing material separates the top and bottom terminals as shown. 
   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.