Patent Abstract:
An electrical pin contact is provided that includes an initial contact portion joined to a main body. The initial contact portion has a lead end configured to be inserted into a female contact and an external surface with a tapered contour extending between the lead end and the main body. The external surface includes at least one recessed cavity formed therein to define a void in the tapered contour for receiving material accumulated during a mating operation.

Full Description:
BACKGROUND OF THE INVENTION 
     Certain embodiments of the present invention generally relate to a contact configured to reduce the insertion force experienced during a mating operation. 
     Numerous contacts have been proposed with different shapes and sizes to establish electrical communication between mating halves of a connector assembly. Often these contacts are arranged in arrays of multiple contacts. With advances in technology, contacts are declining in size, in order that the average number of terminal positions per electrical connector may increase. As the number of contacts increases, the insertion force required to mate the connectors similarly increases. 
     One common shape for the male contact is a pin that is accepted between beams of a female contact. The male and female contacts are generally plated to provide desired electrical performance characteristics. However, when the contacts are mated, the male and female contacts can scrape against each other, causing removal and buildup of plating material. The buildup of plating material interferes with the male contact as it is advanced into the female contact which increases the required insertion force. Harder plating materials may be used to reduce removal and buildup, and consequently reduce insertion forces, but the use of such harder plating materials may result in reduced electrical performance or added cost to manufacture the connector assembly. 
     Often, male contacts are shaped with a leading edge configured to facilitate insertion into the female contact. For instance, the leading edge may be tapered at a transition area near the permanent contacting portion of the male contact. The insertion force of a contact system increases and peaks as the female contact surfaces ride over the transition area. As the male and female contacts join, the plating material collects. In particular, the plating builds up in the transition area due to scraping. 
     A need exists for an improved contact to overcome the above-noted and other disadvantages of conventional contacts. 
     BRIEF SUMMARY OF THE INVENTION 
     At least one embodiment is provided that includes an electrical pin contact comprising an initial contact portion joined to a main body. The initial contact portion has a lead end configured to be inserted into a female contact and an external surface with a tapered contour extending between the lead end and the main body. The external surface includes at least one recessed cavity formed therein to define a void in the tapered contour for receiving material accumulated during a mating operation. 
     The recessed cavity may intersect the tapered contour at opposed lateral edges. The lateral edges converge proximate the lead end and proximate the main body. Further, the pin contact may comprise a transition area joining the initial contact portion and the main body. The main body includes a mating contact portion having a cross section with a first area, and the initial contact portion includes a front edge having a cross section with a second area. The second area is smaller than the first area. 
     Optionally, the initial contact portion may include a tapered rectangular cross section having first and second recessed cavities in top and bottom surfaces of said initial contact portion. 
     At least one embodiment provides an electrical contact system comprising a contact pin and a female contact matable with the contact pin. The contact pin includes a tapered contact portion joined to a main body. The tapered contact portion includes an evenly contoured external surface and an indentation recessed into the external surface. The female contact includes at least one contact portion configured to contact the main body of the contact pin when the contact pin and the female contact are in a fully mated position. The female contact frictionally slides over the external surface of the contact pin proximate the indentation. 
     The female contact may slidably engage the contact pin on opposite sides of the indentation when the contact pin is inserted into the female contact. Optionally, the female contact may include a resiliently deflectable beam configured to contact the contact pin. The resiliently deflectable beam contacts the tapered contact portion and slides over the indentation as the contact pin is inserted into the female contact. Additionally or alternatively, the tapered contact portion may include a front edge and generally conic sloped surface leading from the front edge to the main body. 
     At least one embodiment provides a contact pin and a female contact matable with the contact pin. The contact pin includes an initial contact portion joined to a main body. The initial contact portion includes an external surface and an indentation recessed into the external surface. The main body includes a mating contact portion. The contact pin includes a transition area joining the initial contact portion and the mating contact portion. The mating contact portion has a substantially rectangular cross section. The initial contact portion includes a front edge having a cross section that is smaller than the rectangular cross section of the mating contact portion. Also, the initial contact portion includes a sloped surface leading from the front edge to the transition area. The female contact includes at least one contact portion configured to contact the main body of the contact pin when the contact pin and the female contact are in a fully mated position. The female contact frictionally slides over the external surface of the contact pin proximate the indentation. The female contact also includes a resiliently deflectable beam configured to contact the contact pin. The resiliently deflectable beam contacts the initial contact portion and slides over the indentation as the contact pin is inserted into the female contact. 
     The electrical contact system may include a pair of opposed resilient beams receiving the male contact pin. Further, the indentation may extend substantially from a lead end of the tapered contact portion to the transition area. 
     Certain embodiments of the present invention thus provide an electrical contact that reduces the required mating insertion force. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a perspective view of a contact system, when in an unmated position, formed in accordance with an embodiment of the present invention. 
     FIG. 2 illustrates a top plan view of an end portion of a male pin formed in accordance with an embodiment of the present invention. 
     FIG. 3 illustrates a sectional view of the male pin taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 illustrates a side perspective view of a female contact formed in accordance with an embodiment of the present invention. 
     FIG. 5 illustrates a perspective view of a contact system, when in a fully mated position, formed in accordance with an embodiment of the present invention. 
    
    
     The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, embodiments which are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentality shown in the attached drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates an electrical contact system  10  including a male pin contact  12  and a female contact  14 . The female contact  14  accepts the pin contact  12  to establish electrical communication therebetween. The pin contact  12  may be part of an array (not shown) of similar pin contacts  12  held by a first connector (not shown). The female contact  14  may be part of a corresponding array (not shown) of similar female contacts  14  held by a second connector (not shown). Due to the mating of the pin contacts  12  and female contacts  14 , the first and second connectors provide electrical communication therebetween when joined. 
     FIG. 2 illustrates a top plan view of the pin contact  12 , and FIG. 3 illustrates a sectional elevation view of the pin contact  12  taken along line  3 — 3  of FIG.  2 . The pin contact  12  may have a circular, oval, square, or rectangular cross-section, or any other desired shape. The pin contact  12  includes an initial contact portion  20  joined to a main body  21  at a transition area  23 . The pin contact  12  also includes a top  24  and a bottom  26  joined by sides  28 . In the illustrated embodiment, the top  24  and bottom  26  are substantially identical and may be treated as interchangeable. The top  24  and bottom  26  are separated by a height  27  (FIG.  3 ), and the sides  28  are separated by a width  29  (FIG.  2 ). While FIGS. 2-3 illustrate a substantially even height  27  and width  29 , one, or both dimensions may vary along a tapered cross-section. The main body  21  includes mating contact portions  22  on the top  24  and bottom  26  of the pin contact  12 . Me mating contact portions  22  are configured to be in electrical communication with the female contact  14  when the pin contact  12  is in a final mating position with the female contact  14 . Rearward of the mating contact portion  22 , the main body  21  of the pin contact  12  is mounted to an electrical connector (not shown). 
     The front of the pin contact  12  terminates at a front edge  30 . The front edge  30  has a smaller cross-sectional area than that of the pin contact  12  at the mating contact portion  22 , thereby providing easier initial entry into the female contact  14 . A sloped surface  32  joins the front edge  30  to the main body  21  at the transition area  23 . The sloped surface  32  may be a generally conical shape sloping from the front edge  30  at an acute angle  34  for a distance  35 . The angle  34  and distance  35  may vary depending upon several factors such as the length of the travel during mating and the insertion forces. 
     The pin contact  12  includes one or more dimples  36  in the sloped surface  32 . The dimple  36  recedes beneath the sloped surface  32  and provides a depressed or indented cavity in which scraped material (e.g., plating, corrosion, or other) may accumulate instead of building up elsewhere. The dimple  36  begins at a leading point  37  near the front edge  30  and extends back toward the main body  21  of the male pin  21 . The leading point  37  is located longitudinally along a center line  31  of the pin contact  12  and at intermediate point between the front edge  30  and the transition area  23 . The boundary of the dimple  36  expands laterally outward from the center line  31  of the male pin and rearward toward the main body  21  along two lateral edges  38 . Proximal to the transition area  23  where the initial contact portion  20  is joined to the main body  21 , the lateral edges  38  are joined by a back edge  40  that marks the rearward boundary of the dimple  36  extending past the transition area  23 . By way of example, the dimple  36  may be coined into the pin contact  12  after the sloped surface  32  has been formed. In FIG. 2, the dimple  36  is substantially cone shaped. However, the shape of the dimple  36  may vary. For example, the dimple  36  may be oval, circular, rectangular, triangular, and the like. In the illustrated embodiment, there are opposed dimples  36  in the initial contact portion  20  located proximal to both the top  24  and bottom  26  of the pin contact  12 . Optionally, only one dimple  36  may be provided, or alternatively, 3 or more dimples  36 . 
     FIG. 4 illustrates a perspective view of the female contact  14 . The female contact  14  includes a front portion  50  and a rear portion  52 . The rear portion  52  is mounted to an electrical connector (not shown) and the front portion  50  accepts and engages the pin contact  12  when fully mated therewith. 
     The front portion  50  includes an upper beam  54  and a lower beam  56  extending generally away from the rear portion  52  and shaped to converge on one another. The upper beam  54  and lower beam  56  are resiliently flexible. A gap  58  may separate the upper beam  54  and the lower beam  56  at the point where they are nearest each other. An upper contact portion  60  and lower contact portion  62  are located on the upper beam  54  and lower beam  56 , respectively, proximal to the point at which the upper beam  54  and lower beam  56  are nearest each other. The upper contact portion  60  includes an upper central area  61  proximal to its longitudinal center. The lower contact portion  62  includes a lower central area  63  proximal to its longitudinal center. The gap  58  is dimensioned to be smaller than the height  27  of the pin contact  12  at the transition area  23 . Thus, when the pin contact  12  enters the gap  58 , the upper beam  54  is biased upward in direction A and/or the lower beam  56  is biased downward in direction B. The resiliency of the upper beam  54  and the lower beam  56  ensures consistent contact between the pin contact  12  and female contact  14 . 
     As the upper beam  54  and lower beam  56  extend away from the rear portion  52  past the upper contact portion  60  and the lower contact portion  62 , the upper beam  54  and lower beam  56  are shaped to extend away from each other, terminating at upper and lower leading edges  64  and  66 , respectively, forming a mouth  68 . The distance between the upper beam  54  and lower beam  56  at the mouth  68  is greater than that at the gap  58  and also greater than the height  27  of the pin contact  12  at the transition area  23 . Thus, the mouth  68  cooperates with the front edge  30  of the pin contact  12  to facilitate alignment when the pin contact  12  and female contact  14  are first brought into contact 
     One or both of the pin contact  12  and female contact  14  may be plated. The plating may be, for example, gold plating or solder. One or both of the pin contact  12  and female contact  14  may also have a zinc underplating. Further, the pin contact  12  and female contact  14  may each have substantially similar platings, so that similar compositions contact each other when the pin contact  12  and female contact  14  are mated. 
     With particular reference to FIGS. 1 and 5, the mating process for the pin contact  12  and female contact  14  will now be described. FIG. 1 illustrates the pin contact  12  and the female contact  14  while in an unmated position, and FIG. 5 illustrates the pin contact  12  and female contact  14  while in a fully mated position. 
     Prior to mating, the pin contact  12  and female contact  14  are aligned so that the front edge  30  of the pin contact  12  faces toward the mouth  68  of the female contact  14 . Also, the pin contact  12  is oriented such that the top  24  will contact the upper beam  54  of the female contact  14 , and the bottom  26  will contact the lower beam  56 . In practice, the pin contact  12  and female contact  14  may be symmetric, so the proper orientation may only require that the dimples  36  (see FIGS. 2-3) of the pin contact  12  be aligned with upper and lower contact portions  60 ,  62  (see also FIG. 4) of the female contact  14 . With the pin contact  12  and female contact  14  aligned as described above, the pin contact  12  and female contact  14  are brought together. 
     As the pin contact  12  and female contact  14  are brought together, the front edge  30  of the pin contact  12  enters the mouth  68  of the female contact  14 . As the pin contact  12  and female contact  14  are further urged together, the mouth  68  guides the front edge  30  of the pin contact  12  into the gap  58  of the female contact  58 . The sloped surface  32  of the pin contact  12  then enters the gap  58 . As the pin contact  12  is advanced, the initial contact portion  20  of the pin contact  12  contacts the upper contact portion  60  and lower contact portion  62  of the female contact at the gap  58 , resulting in the scraping of plating between the initial contact portion  20  and both the upper contact portion  60  and lower contact portion  62 , as well as upper beam  54  and lower beam  56  biasing away from each other. Due to the conical shape of the sloped surface  32 , the upper central area  61  of the upper contact portion  60  and/or the lower central area  63  of the lower contact portion  62  will first contact the initial contact portion  20 . 
     The leading point  37  of the dimple  36  will then encounter the upper contact portion  60  and lower contact portion  62 . At this point, the dimple  36  provides a cavity into which accumulated scrapings are deposited. Also, the lateral edges  38  effectively move the points of contact between the pin contact  12  and female contact  14  away from the center line  31  and the upper and lower central areas  61 ,  63  of the upper and lower contact portions  60  and  63 , respectively. This shift in the contacting points reduces any riding of the female contact  14  on any plating build up and helps guide plating build up into the dimple  36 . Further, this movement allows any subsequent scrapings which for any reason are not deposited in the dimple  36  to be pushed off toward the sides  28  in order that they will not accumulate at the final points of contact between the pin contact  12  and female contact  14 . Also, the lateral shift of contact points minimizes any scraping of the central areas  61 ,  63  of the upper contact portion  60  and lower contact portion  62 . As these central areas  61 ,  63  are the portions of the female contact  14  that will be contacting the pin contact  12  when the pin contact  12  and female contact  14  are in their final mated position, reducing scraping at the central areas  61 ,  63  helps maintain the proper amount of plating in place and improves electrical performance. 
     Further urging of the pin contact  12  into the female contact  14  results in the transition area  23  contacting the upper contact portion  60  and lower contact portion  62 . After this point, the upper contact portion  60  and lower contact portion ride substantially horizontally on the main body  21  of the pin contact  12 . Because the back edge  40  of the dimple  36  extends substantially to or beyond the transition area  23 , the dimple  36  addresses the scraping accumulation very effectively. 
     The pin contact  12  is then advanced into the female contact  14  until the upper contact portion  60  and lower contact portion  62  contact the mating contact portions  22  of the main body  21  of the pin contact  12 . This position, illustrated in FIG. 5, is the completely mated position. 
     While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications as incorporate those features which come within the spirit and scope of the invention.

Technology Classification (CPC): 7