Patent Publication Number: US-9853385-B1

Title: Axial compliant compression electrical connector

Description:
This application is a continuation-in-part of U.S. application Ser. No. 15/048,148, filed Feb. 19, 2016, which claims priority under 35 USC 119 to U.S. Provisional Application 62/118,120, filed Feb. 19, 2015, and to U.S. Provisional Application 62/191,557, filed Jul. 13, 2015. All of the above applications are incorporated by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention is in the field of electrical connectors, and contacts for electrical connectors. 
     Description of the Related Art 
     An electrical connector device common in the Industry for decades is known as the pogo pin. These devices are typically cylindrical with a pin-like plunger and a helical coil spring, the combination of which forms a compression connector. The pin is urged by the spring into a mating surface which is an electrical connection point. These devices are most commonly used in testing equipment where unusual surfaces must be accommodated and usually require good reliability over many cycles. These devices are not normally used where very high bandwidth is required nor are they typically designed into input-output (IO) devices such as cable interface and permanent circuit board to circuit board connectors. Also typical of these pogo pin devices is reasonably high cost of manufacture and an electrical current path that is not clearly defined. 
     SUMMARY OF THE INVENTION 
     A spring-loaded connector attacks many of the shortcomings of the previously-mentioned pogo devices. In addition this connector lends itself to a variety of applications, which the former is not uniquely qualified for. 
     According to an aspect of the invention, a compliant electrical contact includes: at least two conductive elements (or members); wherein one of the conductive elements has a portion within and movable relative to a portion of another of the conductive elements; and wherein the relative movement of the conductive elements provides a force of the compliant electrical contact against a conductive pad or a noncompliant contact, making an electrical connection with the conductive pad or the noncompliant contact. 
     In an embodiment according to any one or more paragraphs of this summary, the elements include a plunger, and a receiver for receiving the plunger. 
     In an embodiment according to any one or more paragraphs of this summary, the receiver is a fork with a pair of tines, and the plunger engages the fork between the tines. 
     In an embodiment according to any one or more paragraphs of this summary, the plunger resiliently bends the tines by insertion between them. 
     In an embodiment according to any one or more paragraphs of this summary, the plunger can also include a pair of arms or beams that resiliently deform as the plunger is inserted into the receiver. 
     In an embodiment according to any one or more paragraphs of this summary, the plunger will have a hard stop feature or features. 
     In an embodiment according to any one or more paragraphs of this summary, the receiver elements are captured in a header. 
     In an embodiment according to any one or more paragraphs of this summary, at least some of the elements are secured in the connector by retainers that pass into closed or open holes or elongate slots in the elements. 
     In an embodiment according to any one or more paragraphs of this summary, at least some of the elements are replaceable elements. 
     In an embodiment according to any one or more paragraphs of this summary, the receiver includes a pair or more of identical fork elements that form a laminate whose thickness is equal to a single fork thickness. 
     In an embodiment according to any one or more paragraphs of this summary, the laminated fork elements engage the same plunger. 
     In an embodiment according to any one or more paragraphs of this summary, the fork elements have substantially the same shape. 
     According to another aspect of the invention, an electrical connector includes: a header with one or more fork elements imbedded therein; and a companion plunger for each fork element; wherein, each pair of fork and plunger form a conductive electrical path; wherein the relative movement of the conductive elements provides a force of the compliant electrical contact against a conductive pad or a noncompliant contact, making an electrical connection with the conductive pad or the noncompliant contact. 
     According to another aspect of the invention, an electrical connector includes: a header; and compliant contacts within the header; wherein each of the compliant contacts includes at least two conductive elements (or members); wherein one of the conductive elements has a portion within and movable relative to a portion of another of the conductive elements; and wherein the relative movement of the conductive elements provides a force of the compliant electrical contact against a conductive pad or a noncompliant contact, making an electrical connection with the conductive pad or the noncompliant contact. 
     According to another aspect of the invention, the plunger in contact with both tines of the fork receiver forms a redundant or parallel electrical path. 
     According to another aspect of the invention, the total compliant deflection of the electrical path formed by the conductive elements is a constant times the number of forks in the electrical path. 
     According to yet another aspect of the invention, a compliant electrical contact includes: a pair of conductive elements that include: a plunger; and a receiver; wherein the plunger is movable relative to the receiver to put part of the plunger within part of the receiver, to resiliently deform the plunger and/or the receiver, to thereby provide a force of the compliant electrical contact to engage a conductive pad or a noncompliant contact external to the compliant electrical contact. 
     According to a further aspect of the invention, an electrical connector includes: a connector body; and compliant contacts within the body. Each of the compliant contacts includes a plunger and a receiver. The plunger is movable relative to the receiver and the connector body to put part of the plunger within part of the receiver or part of the receiver within part of the plunger, to resiliently deform the plunger and/or the receiver, to thereby provide a force of the compliant electrical contact to engage a conductive pad or a noncompliant contact external to the connector body. Each of the contracts has a plastic slider that surrounds one of the plunger and the receiver, wherein the plunger makes sliding contact while sliding in a channel within the connector body. 
     In an embodiment according to any one or more paragraphs of this summary, for each of the contacts, the plastic slider is overmolded onto the plunger. 
     In an embodiment according to any one or more paragraphs of this summary, for each of the contacts, the plastic slider has a bulged center portion that contacts walls of the channel. 
     In an embodiment according to any one or more paragraphs of this summary, the bulged center portion has a curved surface. 
     In an embodiment according to any one or more paragraphs of this summary, for each of the contacts, the slider is made of a PTFE-filled nylon. 
     In an embodiment according to any one or more paragraphs of this summary, the housing has internal pins, in the channels, that act as stops for travel of the plunger. 
     In an embodiment according to any one or more paragraphs of this summary, when the plungers are sufficiently pressed into the body, the stops engage the sliders such the plungers are elastically deformed, thereby moving tips of the plungers perpendicular to longitudinal axes of the contacts in which the contacts move within the channels. 
     In an embodiment according to any one or more paragraphs of this summary, at least part of the channels are tilted, relative to the longitudinal axes of the contacts. 
     In an embodiment according to any one or more paragraphs of this summary, the tips of the plungers are linear tips. 
     In an embodiment according to any one or more paragraphs of this summary, the at least parts of the channels are tilted 1 to 5 degrees, relative to the longitudinal axes of the contacts. 
     According to a still further aspect of the invention, an electrical connector includes: a connector body; and compliant contacts within the body. Each of the compliant contacts includes a plunger and a receiver. The plunger is movable relative to the receiver and the connector body to put part of the plunger within part of the receiver or part of the receiver within part of the plunger, to resiliently deform the plunger and/or the receiver, to thereby provide a force of the compliant electrical contact to engage a conductive pad or a noncompliant contact external to the connector body. Each of the plungers slidingly engages a channel within the body. At least part of the channels are tilted, such that tips of the plungers initially engage at an angle respective external contact surfaces that are to be electrically connected to the contacts, and then wipes along the contact surfaces as the plunger is deformed. 
     To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The annexed drawings, which are not necessarily to scale, show various aspects of the invention. 
         FIG. 1A  is a side view of an electrical contact according to an embodiment of the invention, with the contact in an extended position. 
         FIG. 1B  is a side view of the contact of  FIG. 1A  in a deflected position. 
         FIG. 2  is an oblique view of an electrical contact according to another embodiment of the invention. 
         FIG. 3A  is an oblique view of an electrical contact, according to another embodiment of the present invention. 
         FIG. 3B  is a front view of the electrical contact of  FIG. 3A . 
         FIG. 4A  is a side view of an electrical contact, according to yet another embodiment of the present invention, in an extended configuration. 
         FIG. 4B  is a side view of the electrical contact of  FIG. 4A , in a deflected configuration. 
         FIG. 5  is a side view of an electrical contact, according to still another embodiment of the present invention. 
         FIG. 6  is an oblique view of a connector using electrical contacts such as those in the previous embodiments, according to an embodiment of the invention. 
         FIG. 7  is an exploded view of the connector of  FIG. 6 . 
         FIG. 8  is an oblique view of part of the connector of  FIG. 6 . 
         FIG. 9  is an oblique view of a common carrier that is formed as part of the process of making the connector of  FIG. 6 . 
         FIG. 10  is an oblique view showing a header formed on the common carrier of  FIG. 9 . 
         FIG. 11  is an oblique view showing the attachment of coaxial cables to the carrier-header combination of  FIG. 10 . 
         FIG. 12  is an oblique view of a device that includes a pair of connectors, one of which has compliant contacts, in accordance with an embodiment of the invention. 
         FIG. 13  is an oblique view of a connector that includes compliant contacts, in accordance with still another embodiment of the invention. 
         FIG. 14  is a partially exploded view of the connector of  FIG. 13 . 
         FIG. 15  is an oblique view of a connector in accordance with a further embodiment of the invention. 
         FIG. 16  is an oblique cutaway view of part of the connector of  FIG. 15 . 
         FIG. 17  is a plan view of a contact of the connector of  FIG. 15 . 
         FIG. 18  is a side view of the contact of  FIG. 17 . 
         FIG. 19  is a side sectional view of the connector of  FIG. 15 , in a first configuration. 
         FIG. 20  is a side sectional view of the connector of  FIG. 15 , in a second configuration. 
     
    
    
     DETAILED DESCRIPTION 
     An electrical connector is revealed that has unique useful characteristics. A sheet metal fork supplies the stored energy that imparts a force to a second member—a plunger that makes contact with the mating circuit. The plunger can be configured to increase or decrease the force or deflection and can be designed with various connection ends with different contact characteristics. 
     As an alternative to pogo pins, an electrical connector may have a series of compliant contacts that include plungers engaging compliant members. In one embodiment the compliant members are forks that receive portions of the plungers between tines of the forks, such that movement of the plungers in an axial direction resiliently moves the tines laterally outward, making contact between the plungers and the compliant members. 
       FIGS. 1A and 1B  show one embodiment of the broad concept of a compliant contact, according the invention. The contact  10  includes a plunger  11  and a fork  14 .  FIG. 1A  shows the device in the extended position, and  FIG. 1B  shows the device in the deflected position. The plunger  11  has a tip  17  that fits between tines  18  and  19  of the fork  14 . The deflected tines  18  and  19  cause an inward force on the ramps (sloped surfaces) of the tip  17 , shown at locations  13 , urging the plunger  11  upward against the connecting force F. The opposite end  26  of the plunger  11  is rounded or otherwise narrowed, for engagement with a contact pad on a circuit board or the like. The compliant contact thus has some range of movement, while still providing force against a contacting surface, and providing reversible balanced forces that allow the contact to resume its original shape when the force against it is released. Both of the contact members, the plunger  11  and the fork  14 , have respective holes  20  and  21  in a plunger body  22  and in a fork body  24 , for receiving parts of a connector body, such as molded plastic body retainers or hard stops  12  and  15 , to keep the contacts  11  and  14  held within the plastic body. The fork  14  has a circular hole  20 , with the fork not moving relative to the connector body during operation, and the plunger has an elongated hole  21 , allowing some movement of the plunger relative to the header body. 
     The hole  20  may be a round hole, and/or a hole that has about the same shape as that of the retainer  15  that is in the hole  20 . The retainer  15  may thus keep the fork  14  in place relative to the connector body of which the retainer  15  is a part. The hole  21  has an elongate shape that is larger than the retainer  12  in an axial direction, the direction of the connecting force F. This allows the plunger  11  to move relative to the connector body. 
     The tip (or connection end)  16  at the opposite end of the fork  14  from the tines  18  and  19  may be connected to a wire of a cable, or to another electrical conductor. The rounded or otherwise narrowed plunger end  26  may protrude from the connector body, for coupling to contact pads or contacts of another connector. 
     The connection end  16  of the fork  14  may be used to connect that end of the contact to another conductive member. For example the connection may be used to make connection to a cable or to a circuit board. 
     The plunger  11  and the fork  14  may be made of a suitable electrically-conductive material, such as copper or nickel-plated copper. The connector body that includes the body retainers or hard stops  12  and  15  may be made of a suitable plastic, such as a suitable thermoplastic. 
     Many alternative configurations are possible. For example, one alternative would be a ramped member, akin to the plunger  11 , having a connection end and being fixed relative a connector body, while a forked member, akin to the fork  14 , has a rounded or otherwise narrowed end for coupling to contact pads or other contacts, and is able to move in an axial direction relative to the connector body. 
     The contact  10  may be used in connectors of any of a wide variety of configurations. Some examples of such connectors are described below, but should not be considered limiting. 
       FIG. 2  shows an alternative arrangement for a contact  40 . The contact  40  includes two thin forks  44  and  45 , each similar in configuration to the fork  14  ( FIGS. 1A and 1B ), that are in contact with a plunger  41 , similar to the plunger  11  ( FIGS. 1A and 1B ). The forks  44  and  45  may have substantially identical shapes, and may overlap one another substantially completely, moving parallel to one another, and offset from one another in a direction perpendicular to the direction of movement. The two forks  44  and  45  together may have a thickness that is equivalent to the one-piece (thicker) fork  14  that they replace. Multiple forks provide multiple wear paths. Each wear path is subjected to a fraction of the contact forces imposed by the original one piece fork. 
     The multiple contact forces yield the same functional dynamics as the one piece fork with a fraction of the wear at the surface. For the same precious metal plating thickness, many more cycles would be allowed before the protective layer is compromised, or for a given number of cycles, less plating thickness would be required to achieve similar performance, which yields a cost savings. The multiple forks provide multiple contact points, double the number of contact points relative to an equivalent single fork, thereby providing better electrical contact. 
     In other respects the contact  40  may be similar to the contact  10  ( FIGS. 1A and 1B ). The contact  40  may engage a plastic connector body in a manner similar to that of the contact  10 . 
       FIGS. 3A and 3B  shows another embodiment, a contact  60 . The contact  60  includes a plunger  61  and a fork (receiver)  62 . The fork  62  has tines  68  and  69  that are twisted such that they mate with a plunger ramp  64  on a tip  67  of the plunger  61 , at the same angle, as shown in  FIG. 3B . The result of this modification allows an angled presentation of the plunger  61  relative to the fork receiver  62 .  FIG. 3B  shows the plunger  61  at right angle to the axis of the fork  62 . The plunger  61  engages the compliant fork  62  in a direction perpendicular to a major extent of the compliant fork element  62 , in a plane in which the fork element  62  extends. 
     The contact  60  allows use in a right-angle configuration of connector. For example a tip or connector end  66  of the fork  62  may extend from a connector body (not shown in  FIGS. 3A and 3B ) on a face of the connector body adjacent to another face out of which a rounded or otherwise narrowed plunger end  76  extends. 
       FIGS. 4A and 4B  show a two-fork contact  100  in which a plunger (or plunger fork)  115  incorporates a female fork with tines  118  and  119 , and a receiver  116  incorporates a male fork with tines  120  and  121 . The deformation of two fork elements  118  and  119  allows for an increase in the amount (distance) of compression possible in the contact.  FIG. 4A  shows the plunger fork  115  extended, while  FIG. 4B  shows the plunger fork  115  fully deflected. When the plunger fork is fully deflected, a hard stop is effected by the inside edge  128  of the plunger fork  115  contacting the top of the housing element  129 . The plunger  115  is removable for the purpose of replacement. Protrusions  130  are provided on the insides of both female tines  118  and  119  of the plunger  115  such that they retain the plunger in the housing  131  by interfering with the housing element (stop)  129 . For replacement, the plunger  115  may be extracted. As the plunger is removed, the tines  118  and  119  of the plunger fork  115  will deflect outward as the protrusions  130  ride up the housing element  129 , allowing the plunger  115  to be freed. A replacement plunger may be added by reversing the process. 
     The housing  131  may be a single unitary continuous plastic piece that surrounds the fork elements (tines)  118  and  119 , as well as including the stop  129  and a protrusion  132  into a hole  134 , to hold the receiver element  116  in place. The movement of the plunger  115  within a contact channel  140  allows a plunger tip  144  to extend and retract from the connector body or housing  131 . 
     The tines  120  and  121  have end portions  150  and  151  with ramped (sloped) outer surfaces that engage inner surfaces of the tines  118  and  119 . The end portions  150  and  151  may be thicker than other parts of the tines  120  and  121 , to limit the travel of the tines  120  and  121 , and/or to prevent unwanted deformation of the tines  120  and  121 . 
     Some of the features of the contact  100 , such as the connector body or housing  131  with the channel  140  therein for receiving parts of the contact  100 , may also be a part of other embodiments described herein, such as the embodiments described above. In addition, features of the other embodiments may also be similar to features of the contact  100 ; these similar features are not repeated in the description of the contact  100 . 
       FIG. 5  shows a contact  200 , a four-fork embodiment in which the plunger  215  incorporates a female fork as in the contact  100  ( FIGS. 4A and 4B ). A center receiver  222  incorporates mirror image male forks  231  and  232  on opposite ends, and is free to move vertically between housing elements  223  and  224 . The contact  200  also has a bottom receiver  225  that has a female fork and is fixed relative to the housing  226 . The conductive elements or members  215 ,  222 , and  225  are located in a channel  240  in the housing  226 . Housing elements  223 ,  224 , and  227  represent fixed stops limiting the travel of elements  215  and  222 . The housing element or fixed stop  227  also is a retainer with provisions to allow replacement as before. This arrangement of four forks will yield four times the deflection of the single fork version in the contact  10  ( FIGS. 1A and 1B ). 
       FIG. 6  shows a connector  300  that electrically attaches sixty (60) co-axial cables  329  to a circuit board  330  using the principals outlined above. The connector  300  containing a co-axial bundle of cables  329  is attached to the circuit board  330  with two thumb screws  331  communicating with threaded inserts in the board  330 . 
       FIG. 7  is an exploded view of the connector  300 , showing details of construction. The circuit board  330  has two threaded inserts  332  embedded that will accept the two thumb screws  331 . The circuit board  330  also has an array of via pads  336 . There are six rows of the pads  336 , spaced equally apart. Each row has twenty one pads at a constant pitch pad to pad. The pads  336  are connected in the circuit board where the beginning pad of each row is a ground circuit and every other pad is also a ground. The pads in between the grounds are signal pads. Every other row is staggered one pitch in order to isolate signal pads row to row. The connector housing  333  is hollow and contains six contact headers  334  only one of which is shown for clarity. Each of the headers  334  has ten co-axial cables  329  attached, for a total of sixty cables. 
       FIG. 8  shows the plunger array  337  which protrudes from the bottom of the housing  333  of the connector  300 , and which will connect in compression to the via pad array  336  of  FIG. 7 . Note the ends of the plungers  338  of the array  337  have two rounded edges latterly disposed, for example as shown at  338   a . These two edges will span over the via holes in the via pads  336  of  FIG. 7 . 
       FIG. 9  shows twenty one female fork receivers  339  all attached to a common carrier  340 , forming a receiver stamping  342 . The common carrier  340  is an artifact of the progressive stamping die and will become the electrical ground buss for every other contact. The common carrier  340  holds all of the fork contacts (receivers)  339  on pitch so that they can be easily loaded into a mold which will overmold a plastic header body. 
       FIG. 10  shows a completed header  344  made from the common carrier  340 . The header body  341  is overmolded onto the receiver stamping  342 . Every other contact tail  343  is removed from the ground buss (common carrier)  340  to form a signal contact position. 
       FIG. 11  shows co-axial cables  329  attached to header contacts which emanate from the header body  341 . The signal wires  346  of the coaxial cables  329  are attached to every other of the contacts. Shields  347  of the coaxial cables  329  are attached to the common ground buss  340 . The plungers  358  are shown added to the receivers  352  and  354 . 
       FIG. 12  shows a device  400  with a pair of connectors  410  and  412  that utilize connection using the compliant contacts  420  of a configuration as described above, such as that of the contact  10  ( FIG. 1 ). The connector  410  includes an array of compliant contacts  420 , of the sort described above and elsewhere herein. The connector  412  includes a corresponding array of noncompliant contacts  422 , which may be conductive pads or vias, either flush with or raised above the surrounding connector material. The connectors  410  and  412  may be held together by any of a variety of known mechanical mechanisms to provide a force to compress the compliant contacts  420  of the connector  410 , to make an electrical connection between the compliant contacts  420  and the corresponding non-compliant contacts  422 . 
     The arrangement of the connectors  410  and  412  may be advantageously usable in a variety of situations. For example the connector  412  with the noncompliant contacts  422  may be part of a device which would be exposed to an environment in which delicate contacts were prone to contamination (such as by dirt, moisture, etc.) or physical damage. In such an environment traditional protruding male contacts or traditional female receptacles (for receiving male contacts) may be unsuitable because of the danger of damage or fouling. However use of the connector  412  with the noncompliant contacts  422  does not present the same danger of damage or fouling of contacts, since the noncompliant contacts  422  are flush or nearly flush with the surrounding nonconductive part of the connector  412 . 
     In one example, the noncompliant connector  412  may be part of a handheld device that is used in potentially damaging environment. After the device is used in the potentially damaging environment, it may then be taken to a different (safer) environment, where it is interfaced with another device, for instance to transfer data. The connector  410  with the compliant contacts  420  may be part of the device with which the handheld device interfaces with. 
       FIGS. 13 and 14  show a mezzanine connector  500  which can be used to engage sets of noncompliant contacts or contact pads at either end (both top and bottom). Both elements of each compliant contact  510  of the connector  500  may move relative to the body or header  512  of the connector. The connector  500  may be used to link two other connectors, or a pair of circuit boards, for example. The connector  500  may be stacked layers of modules  520 , each containing a row of the contacts  510  interspersed between parts of the body  512 . 
       FIGS. 15-20  show another embodiment, a five-position connector  600  that has a compliant contacts  610  within a connector body or housing  612 . The contacts  610  have respective plastic plungers  614  that surround the contacts  610  within the housing  612 . The plastic sliders  614  may be molded around the contacts  610 . The sliders  614  may be made of any suitable plastic, for example a polytetrafluoroethylene (PTFE) filled nylon, plastics that have superior wear characteristics. The plastic sliders  614  slide within guide channels  616  within the housing  612 , forming a bearing surface that rides on the walls  617  of the molded plastic guide channels  616 . The plastic-to-plastic sliding contact between the sliders  614  and the walls of the guide channels  616  may produce less wear than in a plastic-to-metal sliding contact, for example avoiding eroded material. In addition, the sliders  614  may have radiused or bulged middle portions  618  that present curved surfaces  620  to contact the walls of the guide channels  616 . Contact between the guide channel walls and edges and surfaces of the contacts  610  is thus avoided. In particular the contacts  610  may have rough stamped edges. The plastic-to-plastic contact may result in longer life and may maintain more consistent placement of the contacts  610  within the housing  612 . 
     The contacts  610  have linear tips  622  at ends of plungers  624 . The linear tips  622  may be at a 90-degree angle relative to the longitudinal direction along the contacts  610 , the axis of motion of the plungers  624 . The contacts  610  also have split ends or forks  626 , the operation of which is described above in relation to other embodiments. (The forks engage other contact parts, such as receivers, that are not shown in  FIGS. 15-20 , but are similar to those described above with regard to other embodiments.) The forks  626  straddle stops or pins  630  of the body or housing  612 , which are interior posts within the housing  612  that provide limits to the travel of the contacts  610  within the guide channels  616 . 
     With attention in particular to  FIGS. 19 and 20 , the channels  616  may be two-part channels, with slightly different orientations. The channel upper (plunger) portions  632  are tilted out of the vertical relative to the channel lower (fork) portions  634  and a housing top surface  638 . In an example embodiment the channel upper portion is tilted 2.4 degrees from the vertical. More broadly the channel portion may be tilted from 2 to 3 degrees from the vertical, or from 1 to 5 degrees from the vertical. 
     As shown in  FIG. 19 , when the plunger  624  is at its maximum extension the tip  622  of the plunger  624  is offset form the (vertical) axis centerline  644 , which is the axis of motion of the contact  610  as the contact moves within the channel  616 . This is the condition that the connector  600  is in prior to making a connection with a contact surface  650  of a part or connector  654  with which the connector  600  is making a connection. In this configuration part of the plastic sliders  614  protruding from the openings in the housing or body  612  that lead to the channels  616 . 
       FIG. 20  shows the plunger  624  compressed until the slider  614  makes contact with the stop or pin  630 . That compression of the plunder  624  against the pin  630  causes the plunger  624  to elastically deform such that the tip  622  is no longer offset from the axis centerline  644  of the lower channel portion  634  (and of the body or housing  612 ). This deformation results in the radiused tip  622  moving along the contact surface  650  with which it electrically connects. This wiping action of the tip  622  moving along the contact surface  650  results in an improved electrical coupling. This wiping action is perpendicular to the axis  644 . 
     The tips  622  may have a slightly curved shape, for example having the shape of a portion of a cylinder that is perpendicular to the axis of motion of the plunger  624 . The cylinder portion that is the shape of the tips  622  may be an arc of 15 to 30 degrees, although this range is only an example and should not be considered limiting. The curved tip surface avoids any sharp edges coming into contact with the surface or pad  650  as the tip wipes across the contact surface  650 . Contact from sharp edges could dig into the pad  650  or scrap the pad  650 , causing damage which would be undesirable. This shape may also provide a larger Hertz stress, which yields a lower contact resistance. The wiping action of the tip  622  across the pad or surface  650  may remove any contaminants on the surface  650 , such as a thin layer of oxide from corrosion, thereby providing a better electrical connection. 
     One or more of the features of the contacts  610  may be incorporated in other embodiments described herein. Examples of features that may be incorporated in other embodiments are one or more of the plastic slider  614 , the linear tip  622 , and the channel  616  with an angled portion that causes the tip to wipe across a conductive surface that the plunger  624  engages. 
     Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.