Abstract:
A method of fabricating an electrical connector contact comprising the steps of providing a conductive contact including opposing beams defining a contact gap therebetween and a joint portion joining the opposing beams and re-positioning at least one of the beams to reduce dimension of the contact gap by applying a force to the contact to make it be displaced.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the invention 
         [0002]    The present invention relates generally to electrical connectors and more specifically to a connector contact comprising two opposing beams with a gap therebetween. The invention also relates to a process for fabricating such contacts. 
         [0003]    2. Description of Related Art 
         [0004]    Conductive contacts comprising two opposing beams with a gap therebetween are widely used in connectors for connecting a flexible printed circuit or cable (FPC), a flexible flat cable (FFC) and so forth. All of these cables and circuits will be generally referred to as “FPC” hereafter for convenience. Due to the trend toward small dimensional electronic components, today&#39;s connectors are increasingly characterized by lower profile thereof. In response to this lower profile request, contact gaps of contacts should be minimized. However, the contact with an extremely small contact gap would be difficult to blank under normal stamping conditions. 
         [0005]    In addition, to allow the FPC being inserted into the contact gap with Zero-Insertion-Force, one of the beams, usually the upper beam, is deflectable by driving of an actuator so that when the actuator is opened for insertion of the FPC, the upper beam is opened up by a cam portion of the actuator for broadening the contact gap to receive the FPC, and when the actuator is closed, the normal force from the upper beam is applied to the FPC to make electrical contact. It is expected to ensure that the normal force applied to the FPC from the upper beam is high enough to achieve a reliable connection between the FPC and the contacts, especially after repeated opening and closing operation driven by the actuator. 
         [0006]    Therefore, it is desired to have a contact in which the contact gap is minimized and the normal force applied to the FPC from the upper beam is high enough to ensure a reliable electrical connection. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the present invention is to provide a conductive contact with a small contact gap. 
         [0008]    A second object of the present invention is to provide a conductive contact from which the normal force applied to the FPC is high enough to ensure a firm electrical connection. 
         [0009]    A third object of present invention is to provide a two-step process for fabricating conductive contacts with small contact gap. 
         [0010]    In order to achieve above-mentioned objects, a contact in accordance with the preferred embodiment of the present invention is fabricated by a method comprising the steps of providing a conductive contact including opposing beams defining a contact gap therebetween and a joint portion joining the opposing beams and re-positioning at least one of the beams to reduce dimension of the contact gap by applying a force to the contact to make it be displaced. 
         [0011]    Other objects, advantages and novel features of the present 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 
         [0012]      FIG. 1  is an assembled perspective view of an FPC connector including contacts in accordance with a preferred embodiment of the present invention; 
           [0013]      FIG. 2  is an exploded perspective view of the FPC connector shown in  FIG. 1 ; 
           [0014]      FIG. 3  is a cross-sectional view of  FIG. 1  taken along line  3 - 3 , wherein an actuator is placed at a closed position; 
           [0015]      FIG. 4  is a cross-sectional view similar to  FIG. 3 , but wherein the actuator has been rotated to an open position; 
           [0016]      FIG. 5  is a perspective view of a strip of contacts schematically showing the fabricating process of the contacts in accordance with the preferred embodiment of the present invention; and 
           [0017]      FIG. 6  is a view contrastingly showing a contact prior to being processed and a contact after being processed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The present invention will be discussed hereafter in detail in terms of the embodiments of the present invention. However, any well-known structure or process is not described in detail in order to avoid unnecessary verbosity. 
         [0019]    Referring to  FIGS. 1-4 , by way of example, a plurality of contacts  1  in accordance with the embodiment of the present invention are designed to be used in an FPC connector  100  for connecting an FPC (not shown). Each contact  1  comprises an upper beam  11  and a lower beam  12  defining therebetween a gap, the minimal  13  of which serves as a contact gap for contactably receiving the FPC, a joint portion  14  joining the upper beam  11  and lower beam  12 , and a solder foot  15  extending from the joint portion  14  for being soldered to a printed circuit board (not shown). 
         [0020]    The connector  100  further comprises a housing  2  for receiving the contacts  1  and an actuator  3  for urging the contact  1  to open for receiving the FPC and to close for establishing electrical connection with the FPC, and a pair of retaining ears or end clips  4  for retaining the actuator  3  in the housing  2 . The housing  2  has an upward opening  21  in the top face thereof and a contact-retaining portion  23  adjacent to the rear face thereof. The contact-retaining portion  23  comprises a plurality of ribs  231  and spines  232  between every two adjacent ribs  231 . During assembling, the contacts  1  are forwardly inserted in the opening  21  each to be retained between two adjacent ribs  231  and to have the spine  232  forced through the contact gap  13  to be accommodated between the opposing beams  11  and  12 . The actuator  3  is formed into a plate form with an engaging edge comprising a plurality of through holes  31  provided for the free ends  111  of the upper beams  11  to go through during pivotal rotation of the actuator  3 , a plurality of cam portions  32  provided by the forming of the through holes  31 , and a pair of end shafts  33  respectively extending from longitudinal ends thereof. In assembly, the cam portions  32  are respectively positioned under the free end  111  of the upper beams  11 , and the end shafts  33  rotatably rest in recesses  24  defined at the side portions of the housing  2  and further restricted by the retaining ears or clips  4  assembled to the recess  24 . Thereby the actuator  3  is rotatably pivoting on the shaft portions  33  between an open position where the upper beams  11  are opened up by the cam portions  32  for receiving the FPC and a closed position where the upper beams  11  close to original position to apply a normal force to the FPC received in the contact gaps  13 . 
         [0021]    Referring to  FIG. 5 , the contact  1  and the process by which it is fabricated will be detailedly described hereafter. Generally, contacts are formed into their final configurations directly through a stamping process in which a metal strip is punched into a plurality of patterned blanks which are then progressively formed into the final contact configuration. However, in response to the lower profile request of the connector  100 , the contact gap  13  here should be reduced to a desired dimension. For example, in the case that the height of the connector is reduced to 0.8 mm, then the contact gap  13  should be reduced to less than 0.06 mm. But such a small gap is difficult to blank under the stamping conditions because a punch with such a thin profile would not be able to withstand the stamping pressure. Thus the present invention introduces essentially a two-step process to fabricate the contact  1  with a minimal contact gap. The two-step process includes a normal stamping process for initially providing the contact with a normal contact gap dimension and a re-positioning process for subsequently re-positioning and closing one or both of the two opposing beams to reduce the contact gap to a desired dimension. 
         [0022]    Firstly, the contacts  1  are stamped from an elongated metal strip processed by a progressive or multistage punch press. As the strip is advanced progressively or indexed through the press, the strip is punched into a plurality of patterned blanks which are then progressively formed into the initial contact configuration. These initially finished contacts  1  are joined by a web thereby facilitating their subsequent separation and installation. 
         [0023]    Subsequently, the strip of initially finished contacts  1  which are still joined by a web is set up, in possibly the same stamping die or in a different fixture, for the re-positioning operation. The re-positioning operation can be achieved by, for example, what is referred to as a tonking process. The tonking process is to drive a pointed punch  6  against a predetermined location on the contact  1  so that the material is displaced in a fashion in which one or more of the contact beams  11 ,  12  will be moved or re-positioned. The tonking punch direction is generally perpendicular to a plane defined by the two opposing beams  11  and  12 , i.e., along a direction perpendicular to the strip from which the contacts  1  are stamped. The best location for the tonking punch can be evaluated by comparing the effects on moving the upper beam  11  and the effects of normal force in the upper beam  11  by tonking varied locations of the contact. Evaluation of the effects of normal force can be determined through a normal force measuring gauge. By way of example, a preferred punch location  141  is at the joint portion  14  adjacent to the upper beam  11 , as best shown in  FIG. 6 . 
         [0024]    Referring to  FIG. 6 , as a result of the tonking operation, the upper beam  11  closes up to the lower beam  12  thereby dimension of the contact gap  13  is reduced from I to II. Based on the desired contact gap dimension, the tonking punch diameter and the tonking depth can be adjusted. By way of example, to reduce the contact gap from 0.14 mm to 0.06 mm or less, a punch with a 0.5 mm diameter and pin-tapered to 0.2 mm would be used, and a 0.038 mm punch depth would be preferred. 
         [0025]    Through such a tonking process, a desired minimal gap dimension is achieved, and a higher normal force from the upper beam  11  is achieved due to work hardening of the material by tonking the high stress area of the contact beam  11  or  12 . Moreover, in this way, the pre-existing contacts used in a higher profile connector can be used in the lower profile connector after their contact gaps are reduced by the tonking process without re-designing the contacts. Furthermore, the tonking process can be done either prior to a plating process or “post-plating”, which can facilitate production of the contacts. 
         [0026]    Another re-positioning method is to coin one or both of the two opposing beams  11 ,  12 . By compressing the beam  11  or  12  at a desired location in the direction perpendicular to a plane defined by the two opposing beams  11  and  12 , i.e. the direction is perpendicular to the strip from which the contacts  1  stamped, the material is displaced to reduce the contact gap  13 . By way of example, compressing the free end of the upper beam  11  would displace its material towards the lower beam  12  and therefore reduce the contact gap  13 . Also, there are still other methods to re-position the beam  11  or  12 , for example, to use slide cams in the die to apply sideward force to the contact beam  11  or  12 , thus closing the beams  11  and  12  in a fashion similar to that of the tonking process. 
         [0027]    It will be obvious to those skilled in the art that many changes and modifications in the preferred embodiments of the invention can be made without departing from the scope of the invention.