Abstract:
An electrical connector includes a electrical connector extending between a pair of mechanical connectors to electrically couple circuits, and a supporting member between the mechanical connectors to reduce twisting of the electrical connector. The supporting member cambered to permit the mechanical connectors to translate with respect to one another. A clamping member includes a tapered clamping surface in an undeformed, unclamped position. The clamping member bends when in a clamped position, resulting in approximately planar clamping surface. Resilient pressure pads on the clamping members bias the electrical connector to the circuit board. The pressure pads are mounted in wells in the clamping members to support a sidewall of the pressure pads. Frames provide additional support to the sidewalls of the pressure pads. The pressure pads include a raised edge along a periphery of a contact surface of the pressure pad. Additionally, or alternatively, a support shoulder in the well cooperates with a recess along a periphery of a mounting surface of the pressure pad to support the sidewall. Alignment structure on the frame cooperates with alignment structure on the clamping members, the printed circuit boards and the electrical connectors to align contacts on the electrical connectors with contacts on the printed circuit boards, and to further align the pressure pads with the contacts.

Description:
TECHNICAL FIELD 
     This invention relates to electrical connectors, and more particularly to an improved socket for electrical connectors coupled to printed circuit boards. 
     BACKGROUND OF THE INVENTION 
     Many computing devices, such as desktop computers, workstations, mainframe and super-computers employ multiple printed circuit boards (“PCB”) that include various microprocessors, printed circuits and other components that must be electrically coupled together to transmit data and/or power. The electrical traces on one or more layers of the printed circuit board form the printed circuits and typically terminate in one or more terminals or contacts for making connections. Every decreasing element sizes, such a pitch (i.e., the spacing between successive components), width, and height, exacerbate the problem of providing secure and reliable connections between the printed circuits. Precise positioning on the order of thousandths of an inch is often necessary. Consistent pressure across each of the many contacts is also desirable to assure a reliable connection. A single failed or intermittent connection of a contact on a printed circuit board can result in large amounts of “down-time” for the computing device, and costly troubleshooting by highly skilled technicians. 
     A reliable, precise, and highly manipulable electrical connector is required to couple printed circuits between printed circuit boards. Additionally the connection should be secure over a time period commiserate with the expected life of the computing device to avoid costly maintenance and should allow easy replacement and/or addition of various computer components such as printed circuit boards. 
     SUMMARY OF THE INVENTION 
     According to principles of the invention, a clamping member of an electrical connector is thicker in a central region than in the end region. The clamp includes a bar that is tapered from the center to the edges when in an undeformed state and unclamped position. The bar is deformed under a force applied at the ends as the clamping members are moved into a clamped position. The result is a generally planar clamping surface when the clamping members are in the clamped position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale and various elements and portions of elements may be are arbitrarily enlarged and positioned to improve drawing legibility. 
     FIG. 1 is an isometric view of a clamping assembly and electrical connector according to the present invention. 
     FIG. 2 is an exploded front, right isometric view of the clamping member of FIG.  1 . 
     FIG. 3 is a partial, cross-sectional view of the member and resilient pad of FIG. 2 taken along section lines  3 — 3  of FIG.  2 . 
     FIGS. 4A-4D are a partial, cross-sectional view of an alternative embodiment of the resilient pad of FIG.  3 . 
     FIG. 5 is a front elevational view of the printed circuit board and electrical connectors received between the clamping members and pressure pads that are undeformed while in an unclamped position. 
     FIG. 6 is a front elevational view of the printed circuit board and electrical connectors received between the clamping member and pressure pads that are deformed while in the clamped position. 
     FIG. 7 is a front elevation of an alternative embodiment of the clamping member. 
     FIG. 8 is a front elevation of a further alternative embodiment of the clamping member. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures associated with computers, printed circuit boards, circuits and mechanical clamps have not been shown or described in detail to avoid obscuring descriptions of the embodiments of the invention. 
     FIG. 1 shows a clamping assembly  10  composed of a clamping member  12 , a frame  14  and pressure pads  16 . An electrical connector  18  is shown in position ready for connection to a circuit board by clamping assembly  10 . The clamping member  12  has a first end  20  and a second end  22  and a central portion  24 . According to a preferred embodiment of the present invention, the central portion  24  is somewhat thicker than at the ends  20  and  22 . This will be explained, and shown in more detail, with respect to FIGS. 5-8. Posts and collars  26  and  28  are provided at each of the ends  20 ,  22  respectively in order to receive and provide alignment with frame  14 . 
     Frame  14  rests on top of and in alignment with clamping member  12 . The frame  14  includes an electrical connector alignment structure in the form of a set of pins  30  sized and dimensioned to engage a pair of holes  32  in the end of the electrical connector  18 . The pins  30  align a plurality of electrode contacts  46  on an end of the electrical connector  18  with the respective pressure pad  16 . The alignment structure may also include, in an alternative embodiment, horizontal guide bars  34  and  36  on either side of the strip so as to position it in the proper location on the pressure pad  16 . In some embodiments, guide bars  34  and  36  are not used and instead the pressure pad and pins  30  are in a recess to provide alignment. Of course, any acceptable alignment structure can be used, and those shown here are merely given for example to illustrate ways in which the electrical connector  18  can be ensured to have proper alignment on top of the pressure pad  16  to make good electrical contact when the clamping occurs, as shown in FIGS. 5 and 6. The alignment structure on the clamping members  12 , frames  14  and electrical connectors  18  cooperate to ensure that the contacts  46  on the electrical connectors  18  precisely align with the contacts  38  (FIGS. 5 and 6) on the surfaces of the respective printed circuit boards  40 . Precise alignment is important to providing secure, reliable electrical connections. 
     FIG. 2 shows an exploded view of the clamping assembly  10 . The clamping member  12  includes a recess  23  into which the pressure pads  16  are positioned. The pads  16  may be held in position by a pressure fit, or by adhesive is desirable, either method being acceptable. The pressure pad  16  includes a raised edge  48  as described in more detail later with respect to FIGS. 3 and 4. The clamping member  12  may include a shoulder  19  adjacent each end in order to provide additional alignment with the frame  14 ; however, this is an optional alignment structure, and different or additional structures can be used. 
     The frame  14  is shaped to be positioned on top of and aligned with the clamping member  12 . It contains apertures in each end to align with the posts and collars  26  and  28  of the clamping member as well as a shoulder mating portion to align and mate with the shoulder  19 . Other configurations may also be used to mate and align the frame  14  with the clamping member  12 . 
     The frame  14  contains apertures  21  that align with and surround pads  16 . The sidewalls of the apertures  21  provide support to the sidewalls of the pad  16  so as to provide a solid surface for even pressure to the electrical contact members  46 . This arrangement of the frame  14 , together with the pad  16  and the clamping member  12  provides for the easy assembly of the clamping assembly  10  as a whole. It also ensures proper and correct alignment of the electrical contacts  46  with the printed circuit boards. 
     In an alternative embodiment, the frame  14  is not used. Instead, the recesses  23  and the clamping member  12  are made deeper and the pad  16  is positioned within the deep recess to provide support to the sidewalls. In addition, the alignment structures  30  are positioned on the clamping member  12  to align and mate with the apertures  32  of the electrical connectors  18 . 
     The frame  14  includes on its upper surface raise guides  34  and  36  to provide an additional alignment structure for the electrical connector  18  when it is connected to clamping assembly  10 . When the clamping assembly  10  is fully assembled, it provides reliable alignment, with solid support for the electrical connectors  18  to be positioned thereon for later clamping to provide electrical connection to the printed circuit board  40 . 
     As shown in FIG. 3, each of the pressure pads  16  include a raised edge  48  along a periphery of the upper surface of the pressure pad. The upper surface of the pressure pad  16  contacts the end portion of the electrical connector  18  to bias the contacts  46  of the electrical connector against the contacts  30  (FIGS.  5  and  6 ). There is a tendency for the periphery of the resilient pressure pads  16  to sag downward and the sidewalls  49  and  51  bulge outward as the clamping assembly  10  applies pressure to the connector  18 . The raised edge  48  counteracts this tendency and helps to evenly distribute the pressure exerted on the electrical contacts  46  through the pressure pads  16  when the clamp is shut. The frame  14 , and the recess  23  in the clamping member  12 , each support the sides walls  49  and  51  of the pressure pads  16  to also alleviate the tendency for them to bulge. As an alternative, instead of a separate, discrete frame  14 , the frame  14  can be an integral portion of the clamping members  12 , for example an upright edge surrounding each of the recesses  23 , or the recesses  23  could be made deeper. 
     As shown in FIG. 3 in a cross-sectional view, the pressure pad  16  fits into recess  23 . The dimensions of the pressure pad  16  are slightly larger than the dimensions of the recess  16  to achieve a press fit of the pressure pad  16  in the recess  16 . The press fit deforms the pressure pad  16 , increasing the rigidity of the pressure pad  16  and reducing the tendency of the sidewalls  49  and  51  of the pressure pad  16  to bulge under pressure. Adhesive can be added if desired to provide rigidity to the mounting in addition to the press fit. The raised edges  48  can be achieve by molding, or by removing material from a center portion of the pressure pad  16 . 
     FIGS. 4A-4D show alternative embodiments of the pressure pad  16  and the recess  23 . In FIG. 4A, the pressure pad  16  has an approximately planar contacting surface and a shoulder  52  formed along a peripheral edge of contacting surface  114  the pressure pad  16 . The shoulder  52  extends around the periphery, and beyond the outer edge of the contact area  114  for the electrical contacts  46 . The shoulder  52  thus provides additional lateral support for the upper surface so as to prevent the bulging of the sidewalls and retain the upper surface in a generally planar configuration during clamping. The recess  23  includes a support surface  54  for the pressure pad  16  about the periphery of the mounting surface. The shape of the shoulder  52  conforms to the shape of the recess  23  in the clamping member  12 . The support shoulder  52  assists in countering the tendency of the sidewalls  51  and  49  of the pressure pad  112  to bulge under pressure. The pressure pad  112  is again press fit into the recess  23 . 
     FIGS. 4B-4D illustrate further alternative embodiments of the pressure pad  16  according to principles of the present invention. The pad  16  includes a central member  150  composed of a first material and a second material  148  that is connected along the sidewalls of the material  150 . Both of the materials,  150  and  148 , can be a rubber or other deformable member. However, the material  148  is slightly more firm than the material used for  150 . For example, the material  148  may be a somewhat harder rubber, or have a more firm response because it is a stiffer elastomeric member than the central portion  150 . Having the pressure pad  16  composed of a two-part material also provides the advantage that when pressure is applied to the upper surface  114 , the pad  16  will remain flat and uniform across this entire surface and provide an even support across the entire upper surface  114  so as to provide solid electrical contact of all pads  46 . 
     FIG. 4C is a cross-sectional view taken along lines  4   c — 4   c of FIG. 4 b  to illustrate the two materials  150  and  158  which comprise the pad  16 . The outer layer  148  can be a sleeve into which the pad  150  is placed. In this embodiment, the pad  150  is slightly larger than the aperture in sleeve  148  so that the pad is compressed and held firmly in position. 
     FIG. 4D is a further alternative embodiment of pressure pad  16  in which the material  148  is like a box having a bottom as well as on the sidewall. This embodiment can be used to provide firm support inside the recess  23  and may be used in place of, or in addition to, an adhesive. The material  148  may also be of the type which works better with the adhesive than the material  150  and thus provides a good contacting surface for bonding the pad  16  to the clamp  12 . 
     As previously stated FIGS. 4B-4D show an alternative embodiment of the resilient pressure pad  112 , including a pressure pad sleeve  148  receiving a pressure pad core  150 . The pressure pad sleeve  148  has a durometer value greater than a durometer value of the pressure pad core  150 . The pressure pad sleeve  148  has an aperture  152  having dimensions slightly smaller than corresponding dimensions of the pressure pad core  150 , to receive the pressure pad core  150  in a press fit. Thus, the pressure pad sleeve  148  supports the sidewall  154  of the pressure pad core  150 . As seen in FIG. 4C, the aperture  152  can extend completely through the pressure pad sleeve  148 , or can extend only partially through the pressure pad sleeve  148  as shown in FIG.  15 . The contacting surface  114  of the pressure pad core  150  is disposed over the contacts  46  on the end portion  48  of the electrical connector  18  to ensure that constant pressure is applied across the contacts  46 . The pressure pad sleeve  148  does not directly over any of the contacts  46 , and so does not directly apply force to the contacts  46 . The pressure pad sleeve can be mounted to the clamping surface  70 , or within the wells  108  of the clamping members  58 ,  60 . 
     FIG. 5 shows two clamping members  12  and the pressure pads  10  undeformed, while the clamping members  12  are in the unclamped position. The frames  14  are not shown to improve the legibility of the drawing. The clamping surface  70  of the clamping member is tapered from a centerline  142 , out toward the ends  20  and  22  of the clamping member  12 . For example, a taper producing an angle θ of approximately 0.573 degrees may be sufficient. Tapers in the ranges of 0.1 to 2.0 degrees may be used. (The taper is not shown to scale in the figure, but shown enlarged for purposes of illustration.) Hence, the space between the clamping members  12  and board  40  increases towards the ends  20  and  22  near clamping bars  43  and  45 . Similarly, the space between the electrical connectors  18  on pressure pads  16  and contacts  38  increases towards the ends  20  and  24  along the length of the clamping member  12  in anticipation of the bending of the clamping members  12  when they are to be clamped. As can be appreciated, when rods  43  and  45  apply force to hold the clamp  12  solid against the printed board  40 , the force will be applied mostly at the end portions  20  and  22 , thus deforming the bar  12 . It is desirable to ensure that all electrical contacts between the connector  18  via contact points  46  and the printed circuit board  40  having contact electrodes  38  are precisely made, with uniform pressure applied to all contacts. 
     Accordingly, the principle of the present invention provides uniform pressure when clamped of all electrical connectors  18  of electrodes  46  to electrodes  38  by ensuring that even pressure is provided along the entire length of the bar  12  even though it is clamped at both ends. The pressure pads  16  are also configured to provide even pressure across the entire surface of the pad for each of the electrical contacts  46  when in the clamped position. As shown in FIG. 5, the pressure pads  16  have a slight upstanding ridge  48  around the edge portions, also as shown in the embodiment of FIG.  3 . Once the clamps  12  are pressed firmly against the circuit board  40 , the pressure pads  16  will be deformed to be uniformly flat across their entire surface and in addition the clamping members  12  will be uniformly flat along the surface which is presented to the printed circuit board  40 , as shown in FIG.  6 . 
     FIG. 6 shows the clamping members  12  of FIG. 5, with the clamping member  58  in a clamped position  6 n circuit board  40 . The taper in the clamping member  12  accommodates the bending of the clamping member  12  to produce an approximately planer clamping surface  70  when the clamping member  12  is in the clamped position. Hence, each of the pressure pads  16  exert a uniform pressure on their respective electrical connectors  18  and printed circuit boards  40 . 
     As can be seen by FIG. 6, when the force is applied through clamping rods  43  and  45  to the end portions  20  and  22 , respectively, the member  12  is brought into flat alignment with the printed circuit board  40  and the clamping surface  70  becomes uniformly flat across its entire surface. The clamp member  12  bulges out slightly on a back surface as it is clamped at both ends. This provides even and steady pressure to the rubber pad  16  in supporting the electrical connectors  18  and contact between electrodes  38  and  46  without such uniform pressure, some of the contacts  46  and  38  may not be touched to each other, creating an electrical open circuit. 
     In addition to the slight deformation of the clamping member  12 , the pads  16  also undergo a slight deformation along their edge surfaces. The upstanding edge  48  is slightly depressed by the edge portions of the electrical circuit board  18 . Those electrical connectors  46  which are on the outermost edges of the electrical connector  18  are provided the same support and even pressure as those at the center portion of the pad  16 . Thus, uniformly flat, and even pressure contact surface  114  is provided to the electrical connectors  46  and  38  to hold them in contact with each other for an extended period of time. 
     The design of the present invention has the advantage that solid electrical contact is assured over long periods of time with high reliability. Over time, the metal, as well as the rubber, may fatigue slightly. The design of the present invention takes such fatigue into account so as to ensure that even pressure is applied over the life of the electrical connection. In addition, in the event that the electrical connectors are to be removed, the clamp member  12  can be easily removed and appropriate adjustments made and then reconnected with a high degree of assurance that even pressure will be applied to all electrical connectors  46  and  38  without loss of connection. 
     FIGS. 7 and 8 illustrate alternative members of the clamp  12  which may be used according to principles of the present invention. The clamp  12  of FIG. 7 tapers from the center portion outward along both surfaces so as to be somewhat thinner in the portions  20  and  22  both on the top surface and on a bottom surface. The central portion  24  thus has a bulge on both the top and bottom, as can be seen in the exaggerated FIG.  7 . FIG. 5 is an alternative embodiment in which a bulge  25  occurs only along the top surface. In this instance, the bottom surface  27  is generally flat between end regions  20  and  22  and does not have a taper or other additional material thereon. The upper surface, which becomes the clamping surface  70 , however, does include a bulge  25  so that the clamping member  12  is slightly thicker at the central region  24  than at the ends  20  and  22 . In this alternative embodiment, the taper to create the bulge  25  may be somewhat larger than that which is used for the taper as shown in FIG. 5, since it is only a single surface that is tapered and not both surfaces. The amount of taper for the bar  12  will of course depend on the amount of force used in clamping the bar as well as the anticipated deformation of the bar under clamping, as can be easily calculated based on the design of each individual clamping member  12 . Accordingly, the amount of taper used in each of the embodiments, for FIGS. 5-8, will be based on the taper needed to present a uniformly flat and even pressure clamping surface  70  once the clamping member  12  is connected to the board  40  to provide electrical contact. 
     FIG. 8 shows a further alternative embodiment according to principals of the present invention. In this embodiment, the clamping member  12  has a uniform thickness from one end  20  to the other end  22 . However, the central portion is arched slightly upward so as to present a slightly increased pressure in the central region. Thus, the upper surface  70  which becomes the clamping surface has a slight arch  27  between the ends, and this arch is exactly the same radius as the arch  29  from the bottom surface  27  so even though the clamping member has a uniform thickness between  20  and  22 , it will provide additional pressure in the central regions so as to have uniform pressure across this entire length when in the clamped position. 
     Although specific embodiments of and examples for, the invention are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the invention, as will be recognized by those skilled in the relevant art. The teachings provided herein of the invention can be applied to other electrical connectors, not necessarily the exemplary clamping electrical connector generally described above. 
     The various embodiments described above can be combined to provide further embodiments. All of the above U.S. patents, patent applications and, publications referred to in this specification are incorporated by reference. Aspects of the invention can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further embodiments of the invention. 
     These and other changes can be made to the invention in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims, but should be construed to include all connectors and clamping devices that operate in accordance with the claims. Accordingly, the invention is not limited by the disclosure, but instead its scope is to be determined entirely by the following claims.