Abstract:
A mezzanine-style connector is provided with male and female engaging parts. The terminals of the female part have bifurcated contact arms and the terminals of the male part have projecting mating blades. The contact arms are cantilevered from a body portion of the female terminal and are structured so that any deflection that occurs is cantilevered, and not torsional deflection.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from prior U.S. Provisional Patent Application No. 60/640,111, filed Dec. 22, 2005.  
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to low insertion force male and female terminal constructions and to electrical connectors incorporating them. More particularly, it relates to a bifurcated female terminal with a pair of cantilevered contact arms that deflect when the contact portion of an opposing blade terminal is mated to the female terminal with the female terminal contact arms not incurring torsional deflection.  
         [0003]     Various single and dual spring arm female contact electrical terminals have been provided in the past for making electrical contact with male terminals such as pins, blades, edge card contact pads and the like. Generally, in these arrangements, the male terminal must be inserted into the female with sufficient force to overcome the resistance to insertion presented by the female terminal. The insertion force of the contact structure includes a lifting component which represents the force required to lift or spread the female contact portions apart to permit passage of the male terminal into the female and also a horizontal frictional component provided as the female contact portions wipe against the male terminal during the insertion.  
         [0004]     In multicircuit arrangements that include a large number of female terminals mounted in a connector adapted to mate with a male connector which also includes a correspondingly large number of male terminals, the individual insertion forces associated with each pair of contacts combine so that the overall insertion force required to mate the male and female connectors can be extremely large.  
         [0005]     U.S. Pat. No. 4,740,180, issued Apr. 26, 1988 describes a low insertion force terminal assembly in which the male blade terminal includes a torsional twist and the female terminal has two contact arms that engage the blade terminal at two different contact points. The torsional twist of the male contact blade requires a complex forming procedure and increases the cost of the terminals and the assembly. Additionally, the slot that is stamped into the female terminals extends to the point of forming of the contact arms, thereby creating areas of high localized stress concentration, which may weaken the contact arms under repeated mating cycles of the connector.  
         [0006]     Accordingly, the present invention is directed to a reliable and inexpensive low insertion force terminal assembly that may be used in high density applications, such as mezzanine connectors and which overcomes the aforementioned shortcomings.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, it is a general object of the present invention to provide a new and improved low insertion force mating electrical contact structure.  
         [0008]     It is another object of the present invention to provide a reliable mating electrical contact structure including an elongated male terminal in the form of a blade and an elongated female terminal with a bifurcated contact portion, the contact portion including a pair of contact arms that extend forwardly of a terminal body portion and which are spaced apart by an intervening slot, the two contact arms each having an arcuate shape that extends along a path on opposite sides of a longitudinal centerline of the terminal body portion.  
         [0009]     Yet another object of the present invention is to provide a blade terminal for mating with a bifurcated female terminal, the blade terminal having a longitudinal contact portion with a pair of recesses on opposing sides, which define a pair of contact surfaces that extend along longitudinal edges of the contact portion, each of the contact edges contacting a single one of the bifurcated contact arms of the opposing female terminal.  
         [0010]     Yet a still further object of the present invention is to provide a female terminal with a pair of contact portion that take the form of elongated arms, each of the arms having an arcuate configuration, the pair of arms being separated by an intervening slot, the slot extending a first preselected distance from a free end, into a body portion of the terminal and the contact arms being formed into their arcuate configuration at a second preselected distance from the free end of the terminal so that any bends in the contact arms are spaced away from the end of the slot, thereby reducing stress which occurs during deflection of the contact arms.  
         [0011]     Yet still another object of the present invention is to provide a terminal with bifurcated contact arms in which each of the contact arms terminates in an enlarged free end that defines a contact surface, the contact surface being formed by coining the free ends of the contact arms, the coining reducing the thickness of the contact arms at the contact surfaces.  
         [0012]     It is a further object of the present invention to provide a new and improved low insertion force terminal structure utilizing male and female conductive terminals, the male terminals being of the blade type and the female terminals being of the bifurcated contact arm type, the female contact arms providing a means for reliably contacting the blade terminal without relying upon torsion to ensure contact between the male and female terminals.  
         [0013]     Yet a further object of the present invention is to provide a terminal assembly for use with a mezzanine-style connector, the assembly having an insulative base extending in a given direction between two ends thereof, the base having two opposing sides which mate with the opposing ends, the base including a plurality of terminals arranged in alignment with an axis of the base, the base further having a opening along one side which exposes portions of each of the terminals to air  
         [0014]     In accordance with the present invention, a new, low insertion force connector having improved terminals is provided and a plurality of conductive terminals are arranged in an insulative housing. One of the connectors is a male connector, while the other connector is a female connector. Both connectors have insulative housings that receive, as units, arrays of terminals. These terminal arrays include an insulative support member and the terminals are supported by the support member in a line. These arrays are received within slots formed in the connector housings.  
         [0015]     In the male connector, the terminals include flat blade contact portions and the edges of the contact portions are rolled to a radius to define a pair of contact edges that extend longitudinally along the edges of the blade terminal. In the female connector, the terminals include flat body portions which are split by way of a longitudinal slot that extends from a free end thereof into the terminal for a preselected distance to define a pair of bifurcated contact arms.  
         [0016]     These contact arms are formed into an arcuate configuration and extend opposite each other so that one of the contact arms extends above an axis of the body portion and the other of the contact arms extends below the axis of the body portion. The spacing slot extends into the body portion a greater distance than the length of the contact arms so that the contact arms are not formed proximate to the end of the spacing slot so as to reduce any stress concentrations that may form during use of the terminals. This also restricts the contacts arms to largely cantilevered deflection during mating rather than torsional deflection.  
         [0017]     The contact arrays include an insulative base that extends between two opposing ends, and each of the ends including means for engaging an outer housing. A series of these bases are held within a housing to form the multi-contact aspect of the present invention. The bases have a central, hollow portion and groups of terminals are held in each bases and are aligned with a preselected axis of the base. The base&#39;s hollow portion expose one side of the terminals to air and cover the opposite sides of the group of terminals. The terminal groups may then be inserted easily into their outer housings.  
         [0018]     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  
       [0019]     In the course of this detailed description, the reference will be frequently made to the attached drawings in which:  
         [0020]      FIG. 1  is a perspective view of a connector assembly, shown as a mezzanine-style connector assembly which incorporates terminals constructed in accordance with the principles of the present invention;  
         [0021]      FIG. 2  is the same view as  FIG. 1 , but with the two connectors shown in an exploded, unmated condition;  
         [0022]      FIG. 3  is an exploded view of the female connector component of the connector assembly of  FIG. 1 ;  
         [0023]      FIG. 4  is a perspective view of a single terminal assembly of the female connector component of  FIG. 3  showing the terminals arranged in a linear array;  
         [0024]      FIG. 5  is a perspective view of a female terminal that is used in the connector component of  FIG. 4 ;  
         [0025]      FIG. 6A  is a bottom plan view of the female terminal of  FIG. 5 , taken along lines A-A of  FIG. 5 ;  
         [0026]      FIG. 6B  is an elevational view, taken from the mating end and along line B-B of  FIG. 6A ;  
         [0027]      FIG. 6C  is a side elevational view taken along lines C-C of the female terminal of  FIG. 6A ;  
         [0028]      FIG. 7  is a perspective view of a single terminal assembly of the male connector component of  FIG. 2  showing the male terminals arranged in a linear array;  
         [0029]      FIG. 8  is a perspective view of a male terminal that is used in the male connector component of  FIG. 2 ;  
         [0030]      FIG. 9  is a cross-sectional view of the male terminal of  FIG. 8 , taken along lines  9 - 9  thereof;  
         [0031]      FIG. 10  is a perspective view of the male and female terminals engaged together, but removed from their respective terminal support members;  
         [0032]      FIG. 11  is a cross-sectional view taken along lines  11 - 11  of  FIG. 10 ;  
         [0033]      FIG. 12  is a side elevational view of the male and female terminals of  FIG. 10 ;  
         [0034]      FIG. 13  is a cross sectional view of two opposing male and female terminal assemblies, illustrating the support of the terminals therein;  
         [0035]      FIG. 14A  is a cross sectional view of a pair of a portion of  FIG. 3 , illustrating a pair of receptacle terminal assemblies arranged in side-by-side order; and,  
         [0036]      FIG. 14B  is a cross sectional view of a pair of a portion of  FIG. 1 , illustrating a pair of blade, or male terminal assemblies arranged in side-by-side order  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]      FIG. 1  illustrates a connector assembly  50  that is constructed in accordance with the principles of the present invention. The assembly  50  is comprised of two separate interengaging connector components  52 ,  53  ( FIG. 2 ) that include a male connector component  52  and a female connector component  53 . The terms “male” and “female” as used in this description refer to the structure of the terminals, and in this description, the male connector component  52  has a plurality of individual blade contacts that are received between arms of corresponding female terminals that are disposed in the female connector component  53 .  
         [0038]     Each connector component  52 ,  53  can be seen to include a plurality of conductive terminals that are supported in insulative housings  54 ,  55 . Each such housing  54 ,  55  shown is seen to include an outer wall  56 ,  57  that defines a perimeter of the connector component and the male connector component  52  includes a hollow interior cavity  58  into which a mating portion  59  of the female connector component  53  extends.  
         [0039]      FIG. 3  illustrates the female connector component  53  in greater detail and it can be seen that the connector component  53  includes a plurality of conductive terminals  60  that are held within a plurality of terminal support members  70 . The female connector component housing  55  preferably includes a plurality of terminal receiving cavities  49 , each of which receives a single one of the female terminals  60 . Specifically, the contact portions  62  of the female terminals  60  extend into these cavities  49 .  
         [0040]     As shown in  FIG. 4 , the terminals are held together in a linear array with their respective connector components by a plurality of individual insulative support members  70 , each of which includes a body portion  71  having a pair of engagement tabs or similar projections  72  that are disposed on the opposing end faces  73  of the body portions  71 . These projections  72  are inserted into corresponding opposing slots  48  ( FIG. 1 ) which are formed in each of the housings  54 ,  55 . In order to provide an interference fit with the sidewalls of the connector component housing, the projections  72  may include one or more bosses  74  ( FIG. 4 ) which are formed thereon and which will frictionally engage the connector housing slots  48  when the support members  70  are inserted. As shown in  FIGS. 4 &amp; 7 , the terminal support members  70  may be hollow, and thereby include an open central portion  76  that runs widthwise between the two endfaces  73 . These central portions  76  will define a series of air channels  77  between rows of terminals which are embedded in adjacent terminal support members  70 . These support members  70  may be molded over the terminals  60  or the terminals  60  may be stitched into the support members through a slot  78  or they maybe preferably be molded in place within the support members  70 .  FIG. 14A  is a cross-sectional view of a pair of the female terminal assemblies  70  arranged adjacent to each other. It can be seen that only one-half of the terminal support  70  is hollowed with its opening  77  occurring on only one side of the terminals and this structure may be considered as defining a “pocket” or air between adjacent terminal supports.  
         [0041]      FIG. 5  illustrates a female terminal  60  that has opposing tail portions  61  and contact portions  62  that are interconnected by a body portion  63 . The body portion  63  may include one or more notches  64  formed in its sides that facilitates retention of the terminal  60  in a support member  70  when an overmolding process is used to form the terminal support members  70 . A soldering element  65  may be disposed on the tail portion  61  to aid in securing the terminal tail portions to opposing traces on a circuit board (not shown).  
         [0042]     The forward, or contact portion  62  of the terminal is bifurcated, meaning that it includes a pair of spaced-apart contact arms  66  that are spaced apart from each other by an intervening slot  67 . The slot  67  may be considered to run along a longitudinal axis R of the terminal and, as noted, forms two separate contact arms  66  that are intended to contact an opposing male (blade) terminal  90 . The use of two contact arms  66  provides a redundant contact path for connectors using these terminals, and this redundancy not only ensures contact between the male and female terminals of the two connector components  52 ,  53 , but it also lowers inductance of the terminals. It also reduces the insertion force.  
         [0043]     The base shape of the terminal  60  is initially formed by stamping the overall terminal structure from a sheet metal blank (not shown). The slot  67  is stamped to form the pair of arms in the spaced-apart fashion as shown in  FIG. 6A . The contact arms  66  have free end portions  69  that preferably include, as shown, enlarged contact faces  68  that are reduced in thickness but are enlarged in overall size. These contact faces have a general rectangular configuration when viewed from above or below ( FIG. 6A ) but are coined into an arcuate configuration, as best shown in  FIG. 6C . The enlarged contact faces  68  are formed by coining the free end portions  69  to a preselected extent that will reduce their thickness from a thickness T in the body portion  63  ( FIG. 6C ) down to a lesser thickness t and will increase the width of the contact arms at the contact faces from the width w shown in phantom in  FIG. 6A  to the final coined width W. Preferably, the reduced thickness t is about one-half that of the terminal body portion thickness T.  
         [0044]     The contact arms  66  are also formed to include a somewhat arcuate, preferably semi-circular configuration and they are formed in opposite arcuate directions as shown best in  FIG. 6C , where it can be seen that one of the contact arms extends above the longitudinal axis R of the body portion and the centerline C of the terminal  60 , while the other contact arm extends below these axes. The two contact arms meet, or rejoin the axes, in the area of the contact arm free ends  69  and specifically at the enlarged contact faces  68  thereof. The contact faces are formed into a portion of an arc and the bases  80  (or bottom surfaces) of the contact faces are offset from each other along an angled line A as shown in  FIG. 6B  so that each such bottom contact surface  80  lies beneath the top or bottom surfaces of the body portion of the terminal  60  when viewed from the contact end. ( FIG. 6C .) The terminals are stamped and with stamping, the slot  67  is easier to form and obtain the desired clearance for forming the two contact arms, or beams  66 .  
         [0045]     The two contact arms  66  act as a pair of cantilevered beams that extend from the terminal body portions  63  and the structure of the terminals assists in reducing the stress encountered by terminals of the invention during use. As shown in  FIG. 5 , the slot  67  extends for a first preselected distance D 1  from the free ends  69  of the contact arms  66 , while the contact arms  66  do not begin their arcuate configuration at the same distance, but rather a second preselected distance D 2  that is less than the first distance. This is better shown in  FIG. 6C , where it can be seen that the slot  67  begins (or ends) a distance before the contact arms begin to bend up (or down) out of their stamped plane. The difference between the lengths D 1  and D 2  is the distance which the slot extends back from the initial bending of the contact arms. In this regard, the bending or forming of the contact arms occurs spaced away from the leading edge  82  of the slot  67 . In another important aspect of the present invention, the reduced thickness t of the contact faces  69  reduces the stress placed on the cantilevered contact arms. The enlarged widths of the contact faces  69  will flex independently of the contact arms and therefore take into account the variability of the dimensions of the opposing mating blade contacts. The manner of contact between the two terminals is shown best in  FIG. 11 .  
         [0046]      FIG. 8  illustrates a male terminal of the present which is formed as an elongated blade terminal  90  having a body portion  91  that extends between a contact portion  92  and a tail portion  93 , the tail portion also being shown with a soldering member  94 . The body portion  91  may be provided with notches  950  in its sides for retention purposes in instances where the terminals  90  are molded into a support member  70 .  FIG. 7  illustrates an array of male terminal  90  that are maintained in alignment within an insulative terminal support member  70 , having the openings  76  and end projections  72  as mentioned above.  
         [0047]     In order to take advantage of the wide contact faces  68  of the female terminals, the blade terminal  90  is preferably formed with two shallow recesses  95  proximate to the free ends  96  of the contact portions  92 . These recesses define two specific side edges  97 , which are preferably rolled to form a radius as best shown in  FIG. 11  to form cylindrical side edges. The contact faces  68  maintain a point-style contact with these side edges with the contact arms undergoing cantilevered deflection, rather than torsional deflection as is the case with prior art terminals. The cylindrical shape of the side edges need not be exact cylinders, but may include flats  98  on the outboard surfaces of the edges. The presence of the center recess  95  of the blade terminal permits the two contact beam contact surfaces  68  to be slightly out of alignment and still maintain reliable contact with the blade terminal. The blade terminal  90  preferably has a width that is about equal to the center-to-center distance of the contact faces  68  as shown in  FIG. 11 .  
         [0048]     The blade terminals  90  are likewise held in insulative terminal support members  70 , each of which fits into the male connector component  52 . The terminal support members  70  are preferably hollow with an open central portion  76  that runs widthwise between the two endfaces  73 . These central portions  76  will define a series of air pockets  77  between adjacent terminal support members  70 .  
         [0049]     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.