Abstract:
An electrical connector assembly ( 1 ) includes a plug connector ( 2 ) and a receptical connector ( 3 ). The plug connector includes an insulative housing ( 20 ) having a number of passageways ( 205 ) and a number of fingers ( 206 ), and a number of electrical contacts ( 22 ) received in the passageways and supported by the fingers. The receptacle connector has an insulative housing ( 30 ) defining a number of grooves ( 306 ) and a number of electrical contacts ( 32 ) formed with slanted resilient arms ( 322 ) extending in the grooves. The resilient arms guide the fingers to extend into the grooves to establish an electrical connection between the electrical contacts on the fingers and the resilient arms with a low insertion force.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector assembly, and particularly to an electrical connector assembly comprising a plug connector and a receptacle connector matable with the plug connector. 
     2. Description of the Prior Art 
     Various single and dual spring arm female 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 terminal 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 terminal and also a horizontal frictional component provided as the female contact portions wipe against the male terminal during the insertion. 
     In multicircuit arrangements including a large number of female terminals mounted in a connector adapted to mate with a male connector including 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 the female connectors can be extremely large. 
     Earlier efforts to provide an electrical contact structure characterized by reduced insertion force have generally included modifying the female terminal contacts. In U.S. Pat. No. 4,175,821, for example, a female terminal is disclosed including a dual opposed spring arm contact member wherein the contact portions of the opposed arms are axially offset from one another in the longitudinal direction. As the pin contact is inserted between the female spring arms, the pin engages the first spring arm on the female terminal and lifts it out of the way, before contacting the second spring arm and moving that contact out of the way. A lower peak insertion force is provided by the arrangement because the lifting force needed to deflect the female terminal to a final mated position is broken down into two smaller lifting steps, lifting one spring arm at a time during the insertion stroke instead of two at a time. 
     The design described in the patent has several shortcomings. For example, the female terminal is adapted to receive a conventional square pin male terminal which includes a relatively short, chambered tip portion. The tip portion of the male terminal typically is a rough machine surface which wipes against the precious metal plated contact portion on the female terminal. Repeated mating results in abraded contacts which tends to make the contact arrangement electrically unreliable in prolonged use. Increasing the precious metal plating in the contact area results in increased cost which is also undesirable. 
     Another modified low insertion force female terminal is disclosed in U.S. Pat. No. 4,607,907. The female contact in this patent is a stamped and formed terminal including a rearward box member from which extend cantilevered spring arms including contact portions at their free ends. The contact portions are axially longitudinally offset as were the contact portions in the aforementioned patent, but in addition, they are configured so that overshoot the midline of the insertion region which permits lower spring rates to be used. The female contact further includes a horizontal spacing between the cantilevered spring arms so that the contact portions are horizontally spaced one from the other. This permits the contact portions to be plated with precious metals in a lower cost process. This female contact provides a lower peak insertion force for the same reasons, i.e. the male lifts one cantilevered spring arm at a time during insertion. The overshot design of the contact portions permits lower spring rates in the spring members to be used, so that the stiffness of each spring member is reduced and the force required to lift each spring arm contact during pin insertion is reduced. 
     This design also possesses several shortcomings. As with the first mentioned female, the rough cut abrasive edge of the chambered lead-in on the male pin scrapes against the precious metal coated contact portions of the spring arms during pins insertion. Long term electrical reliability in repeated mating operations is generally not obtained. The female terminal is stamped and then formed in a manner which produces a significantly large amount of wasted sheet metal stock. Furthermore, because these female terminals are formed after stamping to provide the box portion and opposed spring arm structure, they cannot be provided on a carrier strip spaced apart by center line spacings adapted for ready insertion in a connector housing in a single stamping operation. Instead, after they are formed, they must be repositioned to a spacing appropriate for insertion into a housing. This requires additional manufacturing and assembly steps in use. 
     Another approach to providing a low insertion force contact is disclosed in U.S. Pat. No. 4,735,588. The mating electrical contact structure described therein includes an electrically conductive elongated tubular female receptacle contact having at least one resilient elongated beam. Either the female tubular receptacle or the male terminal includes a predefined longitudinally extending rotational skew or twist profile. As the male terminal is inserted into the female receptacle, the resilient beam on the male terminal is progressively deflected along the predefined rotational skew. In accordance with the design, the rotational deflection provides a torque which generates the mated contact force between the male and female contacts. The degree of the rotational skew in this contact arrangement determines the amount of progressive deflection during insertion. 
     This design also has some shortcomings. The male terminal member in at least one embodiment must be assembled and the additional assembly steps add to the cost of the contact structure. Another disadvantage in manufacturing is encountered because the interior of the tubular female member is extremely difficult to plate with precious metals satisfactorily after it is formed. The opposed inner surfaces will create field effect interference in plating operations, resulting in poor or lower quality plating. Moreover, the contact design structure is very sensitive to misalignment of the mating female and male terminals. If the male terminal member is positioned to be slightly offset from the central axis of the tubular female, the low insertion force characteristics can be changed into very high insertion forces because a misalignment will tend to deflect or try to deflect nonresilient members in the system. 
     U.S. Pat. No. 4,740,180 discloses a low insertion force mating electrical contact structure which includes a male terminal having a twisted lead-in portion with at least one surface adapted to engage at least one contact of a female terminal. During insertion the twisted lead-in portion of the male terminal is effective to gradually cam outwardly contact portions of a pair of spring arms of the female terminal from an initial position to a final mated position to provide a lower overall insertion force and at the same time provide a high contact normal force between the female and the male terminals. The mating electrical contact structure and camming profile disclosed in this patent have proven effective to provide a highly reliable, lower insertion force contact interface. However, the design is not easily adaptable for miniaturization beyond a certain point, i.e., for reducing individual terminal size in order to produce denser arrays of terminal size in order to produce denser arrays of terminals in increasingly smaller packages. Furthermore, the solid lead-in portion of the male terminal has limited mating depth and does not generally permit applications in which sequential or staggered mating may be required. They may provide potential problems in some specific connector applications. 
     Therefore, an electrical connector assembly with improved low insertion force structure is desired to overcome the disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     A first object of the present invention is to provide an electrical connector assembly comprising a plug connector and a receptacle connector matable with the plug connector with a low insertion force. 
     A second object of the present invention is to provide an electrical connector assembly having a reliable electrical connection between a plug connector thereof and a receptacle connector thereof with a reduced cost. 
     A third object of the present invention is to provide an electrical connector assembly manufactured with a simplified process and without dimension limitation. 
     An electrical connector assembly in accordance with the present invention comprises a plug connector and a receptacle connector matable with the plug connector. The plug connector comprises an insulative housing and a plurality of electrical contacts. The insulative housing comprises a base portion defining a plurality of passageways, a mating portion extending from the base portion and defining a receiving cavity in communication with the passageways, and a plurality of fingers extending from the base portion into the receiving cavity. The electrical contacts extend through the passageways into the receiving cavity to be supported by the fingers. 
     The receptacle connector comprises an insulative housing and a plurality of electrical contacts. The insulative housing comprises a base portion defining a plurality of passageways and a mating portion defining a plurality of grooves extending therethrough and communicating with corresponding passageways. Each electrical contact comprises a slanted resilient arm. Every two electrical contacts are inserted from each groove through one corresponding passageway with the resilient arms thereof resiliently extending in the groove. The resilient arms and the fingers are configured in such a way that the fingers extend into the grooves to establish an electrical connection between the electrical contacts on the fingers and the resilient arms when the mating portion of the receptacle connector is plugged into the mating portion of the plug connector with a low insertion force. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of an electrical connector assembly in accordance with the present invention; 
     FIG. 2 is a view similar to FIG. 1 but taken from a different perspective; 
     FIG. 3 is an assembled perspective view of a plug connector of the electrical connector assembly of FIG. 1; 
     FIG. 4 is a view similar to FIG. 3 but taken from a different perspective; 
     FIG. 5 is a view similar to FIG. 3 but taken from a different perspective; 
     FIG. 6 is an assembled perspective view of a receptacle connector of FIG. 1; 
     FIG. 7 is a view similar to FIG. 6 but taken from a different perspective; 
     FIG. 8 is a perspective view of an insulative housing of the receptacle connector of FIG. 6; 
     FIG. 9 is a top plan view of the electrical connector assembly of FIG. 1 before the plug connector and the receptacle connector thereof are completely mated with each other; 
     FIG. 10 is a front elevational view of FIG. 9; 
     FIG. 11 is a cross-sectional view taken along line  11 — 11  of FIG. 9; 
     FIG. 12 is a cross-sectional view taken along line  12 — 12  of FIG. 9; 
     FIG. 13 is a cross-sectional view taken along line  13 — 13  of FIG. 9; 
     FIG. 14 is a cross-sectional view taken along line  14 — 14  of FIG. 10; 
     FIG. 15 is a cross-sectional view taken along line  15 — 15  of FIG. 10; 
     FIG. 16 is a cross-sectional view taken along line  16 — 16  of FIG. 9; 
     FIG. 17 is a view similar to FIG. 9 but the plug and the receptacle connectors have been completely mated with each other; 
     FIG. 18 is a front elevational view of FIG. 17; 
     FIG. 19 is a cross-sectional view taken along line  19 — 19  of FIG. 17; 
     FIG. 20 is a cross-sectional view taken along line  20 — 20  of FIG. 17; 
     FIG. 21 is a cross-sectional view taken along line  21 — 21  of FIG. 17; 
     FIG. 22 is a cross-sectional view taken along line  22 — 22  of FIG. 18; 
     FIG. 23 is a cross-sectional view taken along line  23 — 23  of FIG. 18; and 
     FIG. 24 is a cross-sectional view taken along line  24 — 24  of FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 to  2 , an electrical connector assembly  1  in accordance with the present invention comprises a plug connector  2  and a receptacle connector  3  matable with the plug connector  2 . 
     The plug connector  2  comprises an insulative housing  20  and a plurality of electrical contacts  22 . The insulative housing  20  comprises a rectangular base portion  200  and a D-shaped mating portion  201 . The base portion  200  comprises a mating face  202 , an engaging face  203  opposite to the mating face  202  and a pair of supporting sections  204  extending from two opposite ends thereof beyond the engaging face  203 . The base portion  200  defines a plurality of passageways  205  extending through the mating face  202  and the engaging face  203 . Referring also to FIG. 14, each passageway  205  comprises a retention section  211  extending from the engaging face  203  toward the mating face  202  and having a diameter/dimension relatively larger than the rest sections of the passageway  205 . 
     The mating portion  201  extends forwardly from the mating face  202  of the base portion  200  and defines a receiving cavity  208  in communication with the passageways  205 . A plurality of fingers  206  extend forwardly from the mating face  202  of the base portion  200  into the receiving cavity  208  of the mating portion  201 . Each finger  206  defines an inclined guiding face  207  at a forward free end thereof, a contact face  209  extending rearwardly from the guiding face  207  and a cutout  210  recessed from the contact face  209 . Every two adjacent fingers  206  are vertically and laterally offset from each other in such a way that the cutouts  210  thereof communicating with each other and commonly communicating with one corresponding passageway  205 . The guiding face  207  of one of every two adjacent fingers  206  faces upwardly while the guiding face  207  of the other of every two adjacent fingers  206  faces downwardly. 
     The electrical contacts  22  are generally planar and each comprises a retention portion  220 , a contact portion  221  extending forwardly from the retention portion  220 , and a tail portion  223  extending rearwardly from the retention portion  220 . The retention portion  220  comprises a plurality of barbs  224  extending outwardly from two opposite sides thereof. The retention portion  220  is constructed to have a width thereof relatively larger than the contact and the tail portions  221 ,  223  and correspond in the dimension thereof to the retention section  211  of the passageway  205  of the base portion  200 . 
     Referring also to FIGS. 3,  4  and  5 , in assembly, the electrical contacts  22  are inserted from the engaging face  203  into the insulative housing  20  of the plug connector  2 . The retention portions  220  are retained in the retention sections  211  by means of the engagement of the barbs  224  thereof and base portion  200 . The contact portions  221  extend into the receiving cavity  208  of the mating portion  201 . Each contact portion  221  is accommodated by the cutouts  210  of two adjacent fingers  206  to be supported by the two adjacent fingers  206 . The tail portions  223  are located outside of the engaging face  203 . 
     The receptacle connector  3  comprises an insulative housing  30  and a plurality of electrical contacts  32 . The insulative housing  30  comprises a rectangular base portion  300  and a D-shaped mating portion  301 . The base portion  300  comprises a mating face  302 , an engaging face  303  opposite to the mating face  302 , a plurality of passageways  304  extending through the mating face  302  and the engaging face  303 , and a pair of supporting sections  305  extending from two opposite ends thereof beyond the engaging face  303 . 
     Referring also to FIGS.  8  and  11 - 14 , each of the passageways  304  comprises a receiving section  308  extending from the mating face  302  toward but not to the engaging face  303  and having a dimension/diameter larger than the rest sections of the passageway  304 . 
     The mating portion  301  extends forwardly from the mating face  302  of the base portion  300  and comprises a plurality of grooves  306  extending therethrough. Each groove  306  communicates with a corresponding passageway  304  to construct a receiving channel  307  of the insulative housing  30 . The grooves  306  are generally rectangular. Each groove  306  is larger in the height thereof than a corresponding passageway  304  and communicates with the corresponding passageway  304 . 
     Each of the electrical contacts  32  comprises a retention portion  320 , a resilient arm  321  extending forwardly from a front end of the retention portion  320  and a tail portion  322  extending rearwardly from a rear end of the retention portion  320 . The retention portion  320  has a width larger than the resilient arm  321  and the tail portion  322 . The resilient arm  322  has a center line thereof along the longitudinal direction of the electrical contact  32  offsetting from a longitudinal center line of the tail portion  322 , which extends from a middle of the width of the retention portion  320 , i.e., the resilient arm  322  and the tail portion  323  are laterally offset from each other. The number of the electrical contacts  32  is twice of the number of the electrical contacts  22  and is twice of the number of the receiving channels  307  of the insulative housing  30 . The number of the electrical contacts  32  is equal to the number of the fingers  206  of the insulative housing  20  of the plug connector  2 . 
     Referring also to FIGS. 6-7 and  19 - 22 , every two of the electrical contacts  32  of the receptacle connector  3  are arranged in such a way that the retention portions  320  thereof and the tail portions  322  thereof respectively abut against each other in a face to face fashion and the resilient arms  321  thereof laterally offset from each other in a vertical opposing manner. The two electrical contacts  32  are inserted from one of the grooves  306  of the mating portion  301  through a corresponding passageway  304  of the base portion  300  to be accommodated in the receiving channel  307  of the insulative housing  30  of the receptacle connector  3 . 
     The retention portions  320  are retained in the receiving sections  308  of the passageways  304  of the base portion  300  while the tail portions  322  partially extend beyond the engaging face  303  of the base portion  300  and the resilient arms  321  extend resiliently in the grooves  306  of the mating portion  301 . The resilient arms  321  in each groove  306  are laterally offset from each other and one resilient arm  321  of the two electrical contacts  32  extends slantedly upwardly in the groove  306  while the other resilient arm  321  of the two electrical contacts  32  extends slantedly downwardly in the groove  306 . 
     Referring also to FIGS. 9-16, during the course of mating the plug connector  2  with the receptacle connector  3 , the mating portion  301  of the receptacle connector  3  is plugged into the receiving cavity  208  of the mating portion  201  of the plug connector  2 . Each pair of adjacent fingers  206  with the contact portion  222  of the electrical contact  22  therein protrude into one groove  306  with the guiding faces  207  thereof guiding the resilient arms  321  in the groove  306  with a lower force. A force needed to mate the electrical contacts  22  with the electrical contacts  32  in the grooves  306 , i.e., the force needed to insert the mating portion  301  into the receiving cavity  208 , increases with the further relative movement of the fingers  206  and the resilient arms  321  due to the slanted configurations of the fingers  206  and the resilient arms  321 . Therefore, a total force, i.e., the insertion force, needed to mate the plug connector  2  and the receptacle connector  3  is reduced compared to conventional electrical connectors (not shown) having electrical contacts and/or housings thereof without slanted configurations. 
     Referring also to FIGS. 17-24, when the plug connector  2  and the receptacle connector  3  are completely/finally mated with each other, a front end of the mating portion  201  abuts against the mating face  302 . The resilient arms  322  have already passed through the guiding and the contact faces  207 ,  209  and reached to electrically contact with the contact portions  221  of the electrical contacts  22 . 
     The electrical contacts  32  of the receptacle connector  3  are formed with simple structures, thereby simplifying the manufacturing process thereof. In addition, the electrical contacts  22 ,  32  all can be provided on a carrier strip spaced apart by centerline spacings adapted for ready insertion in a connector housing in single stamping operation, thereby simplifying the assembly process of the electrical connector assembly  1  and reducing the cost of the electrical connector assembly  1 . 
     The insulative housing  20  has the fingers  206  constructed respectively corresponding to the resilient arms  321  of the electrical contacts  32  in each groove  306  to insert the contact portions  221  into between the two resilient arms  321  without wiping against the precious metal plated on the resilient arms  321 , thereby ensuring the long-term reliability of the electrical connection between the plug and the receptacle connectors  2 ,  3  and further reducing the cost of the electrical connector assembly  1 . 
     The electrical contacts  22  have no twisted structures therein, thereby having no dimension limitation in miniaturization. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.