Abstract:
The present invention provides a process for forming a contact member cable. The cable is a longer version of a contact member and can then be cut into shorter, individual contact members, to meet the particular requirements for a specific connector application. The contact members can be used as the conductive elements for a family of land grid array connectors that provide, among other things, a low profile, uniform electrical and mechanical performance, and reworkability if a contact member is damaged. The connectors are intended to interconnect electrical circuit members such as printed circuit boards, circuit modules, or the like. Such circuit members may be used in information handling system (computer) or telecommunications environments.

Description:
CROSS-REFERENCE OF RELATED APPLICATION  
       [0001]    This application is a continuation-in-part application of copending U.S. application Ser. No. 10/241,945, filed on Sep. 12, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention generally relates to interconnection systems for high speed electronics systems, and more particularly to a shielded elastomeric contact adapted for use in several different connector systems that are capable of high speed data transmission.  
         BACKGROUND OF THE INVENTION  
         [0003]    Electrical connectors that are mounted to a printed circuit board are well known in the art. As the size of the electronic devices in which the printed circuit boards are installed has decreased, the density of the connectors positioned on those boards has increased. Such electronic devices also require electrical connectors, with numerous terminals to be mounted on a printed circuit board in such a manner as to occupy a minimal area of printed circuit board real estate, while at the same time capable of transmitting ever higher data rates.  
           [0004]    In order to provide for a higher density of connectors on printed circuit boards, surface mount technology was utilized. With surface mounting, the conductive pads on the printed circuit board can be closely spaced, thereby allowing more contacts to be mounted in the same area of the board. As the density of the connectors on the printed circuit board increases, the length of the terminals cannot increase significantly without degrading the electrical performance of the electronic device. This is particularly true in electronic devices designed for high speed applications. Typically, high density connectors, which have the shortest path over which the signals must travel, operate optimally. As the density of interconnects increases, and the pitch between contacts approaches 0.5 mm or less, the close proximity of the terminal contacts increases the likelihood of strong electrical cross-talk coupling between the terminal contacts. In addition, maintaining design control over the characteristic impedance of the terminal contacts becomes increasingly difficult.  
           [0005]    The design control difficulties associated with maintaining the characteristic impedance within the necessary limits for optimum high speed data transfer are compounded when such high speed signals must be transmitted between spaced apart systems. Most often, coaxial-type cables and connectors are employed for such data transmission applications. Coaxial cable typically comprises a center conductor that is surrounded by overlapping layers of insulator material and electrical shielding material that extend the length of the transmission line. Coaxial connectors often have a circular center contact, a hollow cylindrical outer contact, and a tubular insulation between them. Such coaxial connectors are interconnected to coaxial cable by electrically and mechanically engaging the center conductor to the center contact and the shielding material to the hollow cylindrical outer contact. Retention features generally must be attached to the outside of the outer contact, since their insertion into slots in the insulation would result in a sudden change in impedance there, resulting in reflectance of signals and consequent increase in the VSWR (voltage standing wave ratio) and signal losses. Each coaxial type connector has a defined characteristic impedance with 50 ohms being the most common, and with losses increasing with deviations from the defined characteristic impedance at locations in the connector.  
           [0006]    The traditional cylindrical shapes used in these types of connector systems often require relatively expensive manufacturing methods, such as machining of the inner contact, to form the coax connector assembly. Such assemblies are normally to large to be of any practical use in a printed wiring board to printed wiring board application. A coaxial-type contact assembly, or connector, with inner and outer contacts separated by insulation, for carrying signals in the range of megahertz and gigahertz, which could be constructed at low cost in a board-to-board configuration would be of significant value.  
           [0007]    Modern electronics requires the use of high frequency and high speed connectors particularly for use in interconnecting circuitry on motherboards or backplanes and daughter cards or other circuit devices. These connectors have often times required shielding or ground planes between the signal pins; e.g., stripline configuration, to provide high frequency signal integrity and minimize interference from outside sources.  
           [0008]    For example, U.S. Pat. No. 6,264,476 discloses an interposer for a land grid array that includes a dielectric grid having an array of holes and a resilient, conductive button disposed in one or more of the holes. The button includes an insulating core, a conducting element wound around the insulating core, and an outer shell surrounding the conducting element. The characteristics of the conducting element and the buttons may be chosen such that the contact force, contact resistance, and compressibility or relaxability of the conductive buttons can be selected within wide limits. The interposer design utilizing such conductive buttons is quite compatible with high data rate, high frequency and high current applications.  
           [0009]    For some applications, however, it is desirable to have a highly dense array or grid of contact members, while maintaining the integrity between the lines, in a board-to-board configuration. As the center line spacing between contact members in a row is decreased, the spacing between adjacent columns of contact members is likewise decreased, thereby necessarily reducing the amount of dielectric housing material between the members of the array. This, in turn, affects the electrical characteristics of the connector system, and in particular reduces the impedance through the connector system. It is desirable, therefore, to have an electrical connector that provides a dense array of contact members, with the impedance characteristics often only found in coaxial connector systems, and arranged in a board-to-board connector system, while maintaining the electrical characteristics associated with connectors having a less dense array of contact members.  
           [0010]    Though there are many types of connectors available, it would be desirable to have a connector with a precisely controlled impedance to reduce signal reflections. It would also be desirable to have a connector which could accommodate fast signals, those with rise times on the order of 250 psec or less. Such a connector should also be durable while at the same time being detachable so that printed circuit printed wiring boards can be joined and separated during use.  
         SUMMARY OF THE INVENTION  
         [0011]    In one embodiment of the invention, a method for making an electrical contact is provided that comprises the steps of advancing a center resilient body along a predetermined path of travel and arranging a plurality of elongate wires around that center resilient body. A dielectric layer applied around the plurality of elongate wires and the center resilient body so as to form an axially continuous contact-cable. The contact-cable is then cut repeatedly so as to form a plurality of individual electrical contacts. In a preferred embodiment of the invention both the advancing and applying steps utilize a fluoropolymer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein:  
         [0013]    [0013]FIG. 1 is a partially exploded, perspective view of a coaxial elastomeric connector system formed in accordance with the present invention;  
         [0014]    [0014]FIG. 2 is a perspective view of a flex circuit base connector system formed in accordance with the present invention;  
         [0015]    [0015]FIG. 3 is a perspective view, partially in phantom, of a compressible contact formed in accordance with the present invention;  
         [0016]    [0016]FIG. 4 is a perspective view of a plurality of flexible connecting elements wound around a compressible insulating core;  
         [0017]    [0017]FIG. 5 is a cross-sectional view of a compressible insulating core having a plurality of flexible conducting elements wrapped around it, as taken along the lines  55  in FIG. 4;  
         [0018]    [0018]FIG. 6 is a perspective view similar to that shown in FIG. 4, but including a compressible outer shell  26 ;  
         [0019]    [0019]FIG. 7 is a cross sectional view of a compressible insulating core having a plurality of flexible conducting elements wrapped around it, and encased within a compressible outer shell, as taken along lines  77  in FIG. 6;  
         [0020]    [0020]FIG. 8 is a perspective view of a plurality flexible conducting elements wrapped around a compressible insulating core, encased within a compressible outer shell  6  and further shielded by shielding layer;  
         [0021]    [0021]FIG. 9 is a cross-sectional view of FIG. 8 as taken along lines  99  in FIG. 8;  
         [0022]    [0022]FIG. 10 is a perspective view similar to FIG. 8, but including an additional shielding layer;  
         [0023]    [0023]FIG. 11 is a cross-sectional view of FIG. 10 as taken along the lines  11  in FIG. 10;  
         [0024]    [0024]FIG. 11 a is a perspective view similar to FIG. 10, but including an additional shielding layer that has been wrapped around a plurality flexible conducting elements disposed upon a compressible insulating core;  
         [0025]    [0025]FIG. 12 is a perspective view, partially broken away of a contact formed in accordance with the present invention arranged just prior to engagement with a contact pad positioned on a portion of a printed wiring board;  
         [0026]    [0026]FIG. 13 is a is a perspective view of a flex circuit connector system formed in accordance with the present invention;  
         [0027]    [0027]FIG. 14 is a partially broken away, perspective view of a contact formed in accordance with the present invention arranged just prior to engagement with a contact pad on a flex circuit;  
         [0028]    [0028]FIG. 15 is a front elevational view of a contact pad having a surface trace formed on a flex circuit;  
         [0029]    [0029]FIG. 16 is a front elevational view of an alternate contact pad having a signal trace exiting through a printed wiring board;  
         [0030]    [0030]FIG. 17 is a further alternative embodiment of board to board interconnect/jumper system formed in accordance with the present invention;  
         [0031]    [0031]FIG. 18 is a exploded perspective view of an interposer adapted for interconnecting a microprocessor or like semi-conductor device to a printed wiring board;  
         [0032]    [0032]FIG. 19 is a perspective view of an alternative shielding layer having a plurality of wires, with each wire being wound in a spiral having a direction of wind, and where the direction of wind of at least one of the wires is an opposite direction to the direction of wind of at least one of the other wires;  
         [0033]    [0033]FIG. 20 is a perspective view of an alternative shielding layer comprising a conductive wire mesh;  
         [0034]    [0034]FIG. 21 is a perspective view of an alternative shielding layer comprising a continuous metallic layer;  
         [0035]    [0035]FIG. 22 is schematic representation of a typical manufacturing system for forming a continuous length of contact-cable in accordance with the present invention; and  
         [0036]    [0036]FIG. 23 is schematic representation of a typical cutting system for forming a plurality of electrical contacts from a continuous length of contact-cable in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0037]    This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.  
         [0038]    Referring to FIGS. 1 and 2, connector system  2  formed in accordance with the present invention comprises a plurality of elastomeric contacts  5  assembled within a housing block  18 , or to portions of a flex circuit  10 . More particularly, each elastomeric contact  5  comprises at least one flexible conducting element  12  wound around a compressible insulating core  14  extending from first end  17  to second end  19  of contact  5  (FIGS.  3 - 4 ). Suitable materials for flexible conducting elements  12  include gold, copper, and other metals or metal alloys of low specific resistivity. Non-noble metals can be plated or coated with a barrier metal covered with a surface structure of gold or other noble metals to ensure chemical inertness and provide suitable asperity distribution to facilitate good metal-to-metal contact.  
         [0039]    Compressible insulating core  14  preferably comprises a fluoropolymer or other suitable resilient dielectric material (FIG. 5). A compressible, insulating outer shell  26  is arranged in surrounding relation to flexible conducting elements  12 , and periodically engages portions of flexible conducting elements  12  and compressible insulating core  14  (FIGS. 3, 6 and  7 ). Flexible conducting elements  12  and compressible insulating core  14  are embedded in compressible outer shell  26  which may be formed from one of the well known elastomeric polymers, e.g., silicone rubber, neoprene, polybutadiene, or similar polymeric materials. In this way, the shell-to-conducting element engaging portions are along substantially the entire surfaces of each of flexible conducting elements  12 . Preferably, compressible outer shell  26  is formed from one of the many fluoropolymers which are substantially free of hydrogen, especially melt-processable copolymers of tetrafluoroethylene with suitable comonomers, such as hexafluoropropylene and perfluoroalkoxyalkenes. Suitable commercially available copolymers include those sold by E. I. Dupont de Nemours under the trade names Teflon FEP and Teflon PFA.  
         [0040]    Contacts  5  are preferably shielded with at least one electrically conductive shielding layer  28  made of individual conductors, wire mesh or, alternatively, a continuous metallic layer, that is arranged in surrounding relation to compressible outer shell  26  and insulating core  14  that is positioned over the inner lying flexible conducting elements  12  (FIGS.  3 , and  8 - 11 ). This arrangement is analogous to a coaxial cable conductor where the central conductor is surrounded by one or more outer conductive shield layers. Shielding layer  28  is often protected by one or more additional dielectric and/or shielding layers  29 . In addition, a variety of arrangements of shielding layer may be employed with the present invention (FIG. 11). For example, one shielding layer  29   a  includes a plurality of wires, with each wire being wound in a spiral having a direction of wind, and where the direction of wind of at least one of the wires is an opposite direction to the direction of wind of at least one of the other wires (FIG. 19). Also, a dielectric layer  29  may be formed from one of the many fluoropolymers which are substantially free of hydrogen, especially melt-processable copolymers of tetrafluoroethylene with suitable comonomers such as hexafluoropropylene and perfluoroalkoxyalkenes. Suitable commercially available copolymers include those sold by E. I. Dupont de Nemours under the trade names Teflon FEP and Teflon PFA may be applied by wrapping (FIG. 11 a). Alternatively, a conductive wire mesh  29   b  (FIG. 20) or a continuous metallic layer  29   c  (FIG. 21) may be used without deviating from the scope of the present invention. Of course, it will be understood that is each embodiment of the invention, an insulating layer surrounds the shielding layer.  
         [0041]    Contacts  5  can be manufactured by first making a cable-like structure, via an extrusion process, and then cutting the cable-like structure into pieces having preselected lengths. Contacts  5  may also be made by other conventional methods, such as injection molding. More particularly, the method of the present invention for forming a plurality of contacts  5  generally comprises providing a continuous length of compressible insulating core  14 , e.g., an elongate solid or tubular fluoropolymer core. A plurality of conducting elements  12  are wound around compressible insulating core  14  in substantially surrounding relation. In one embodiment, conducting elements  12  form a helical coil that surrounds compressible insulating core  14 . A dielectric layer  29  is applied over top of conducting elements  12  and compressible insulating core  14  so as to substantially surround both thereby forming a contact-cable  30 . Contact-cable  30  is then repeatedly and sequentially cut so as to form a plurality of discrete contacts  5 . As indicated herein above, dielectric layer  29  may be applied by wrapping (FIG. 11 a ), extrusion or coating. Additional layers of conductors and dielectric materials may then be applied to form a variety of shielded contacts  5 .  
         [0042]    Several design considerations go into determining the materials and dimensions of the various components for making contact-cable  30 . They include determining the outer diameter, the mechanical, electrical, and physical parameters, the end-use environmental conditions, and understanding how the materials will react/interact with adjoining materials.  
         [0043]    Compressible insulating core  14  allows a continuous manufacturing flow and a physical surface onto which conducting elements  12  may be wrapped to form contact-cable  30 . Compressible insulating core  14  is preferably made of a polymeric material. Here again, a preferred material is one of the many fluoropolymers which are substantially free of hydrogen, especially melt-processable copolymers of tetrafluoroethylene with suitable comonomers such as hexafluoropropylene and perfluoroalkoxyalkenes. Suitable commercially available copolymers include those sold by E. I. Dupont de Nemours under the trade names Teflon FEP and Teflon PFA. Other desirable properties for compressible insulating core  14  are low moisture absorbance, minimal shrinkage, lack of dyes, high tensile strength, low compression force, high melting point, relatively uniform diameter. A low tear strength in compressible insulating core  14  aids in performing a cutting process for the later forming of individual contacts  5 .  
         [0044]    Conducting elements  12  provide a continuous, and preferably redundant electrical path from a first end of contact-cable  30  to a second end. Once subdivided into individual contacts  5 , conducting elements  12  act mechanically as a spring, as well as signal, power or ground interconnection paths. The material for conducting elements  12  is chosen based on mechanical, electrical, and physical requirements. Suitable examples are copper alloys such as cadmium copper, phosphor-bronze and beryllium copper, which are commonly used in the interconnection industry. Desirable properties for conducting elements  12  include high electrical conductivity, low bulk resistance, high yield stress, ductility, low oxidation rate, and a cross-sectional area that is selected so as to provide appropriate conductivity for a specific application. The preferred materials suitable for conducting elements  12  should also be readily available, inexpensive, and have industry-wide acceptance.  
         [0045]    In one example, conducting elements  12  comprise four 0.002 inch diameter beryllium copper wires. There are many possible configurations for orienting conducting elements  12  on compressible insulating core  14 . One way is to spirally wrap them around compressible insulating core  14 , where the wire diameter, the lay length, the spatial layout, and the wrapping configuration determine how the finished contact  5  behaves mechanically and electrically. Conducting elements  12  may be spirally or helically wound in the same direction, in opposing directions, or braided. Conducting elements  12  may also be applied to compressible insulating core  14  by wrapping, braiding, winding, and twisting techniques. In other embodiments, conducting elements  12  may comprise a conductive tape. Optionally, conducting elements  12  may be plated with at least one additional layer of conductive material (e.g., gold) to enhance performance and/or reliability.  
         [0046]    Dielectric layer  29  acts as a protective layer for contact-cable  30  from the surrounding environment, and provides electrical isolation for conducting elements  12  from shielded carriers. It will be understood that the material choice for dielectric layer  29 , along with the shielded carrier, the thickness and material can be used to determine the characteristic impedance of contacts  5 . The maximum thickness of dielectric layer  29  is determined by center-to-center distance between adjacent contacts  5  when mounted in either housing block  18  or flexcircuit  10 .  
         [0047]    Dielectric layer  29  is also preferably made of a polymeric material. A preferred material is one of the many fluoropolymers which are substantially free of hydrogen, especially melt-processable copolymers of tetrafluoroethylene with suitable comonomers such as hexafluoropropylene and perfluoroalkoxyalkenes. Suitable commercially available copolymers include those sold by E. I. Dupont de Nemours under the trade names Teflon FEP and Teflon PFA. Desirable properties for dielectric layer  29  include low compression modulus, low compression set, minimal reversion under end-use environmental conditions over the life of the product, low tear strength, low rate of processing defects (e.g., bubbles, voids, and contaminants), and ease of material handling in manufacture. Also, it is preferable that the material chosen for dielectric layer  29  be readily available, inexpensive, and have industry-wide acceptance. It will be understood that when wrapping dielectric layer  29  (FIG. 11 a) a suitable melting or sintering process step of the type well known in the art is required to effect adhesion and void free coverage of the underlying structures.  
         [0048]    The rigidity of flexible conducting element  12  is selected so that when contact  5  is compressed (or the compressive force is released) the contacting portions urge an identical or substantially corresponding displacement in both flexible conducting element  12  and compressible outer shell  26 , and layers  28 ,  29 . This allows first end  17  and second end  19  of contact  5  to establish and maintain electrical and mechanical contact with between contact pads  31   a ,  31   b  that are located in a corresponding array of contact pads on printed wiring boards  36   a ,  36   b , respectively, by means of the electrical conductors running through contact  5 .  
         [0049]    Referring to FIG. 22, an example of one manufacturing arrangement that is suitable for use with the present invention includes withdrawing a continuous length of compressible fluoropolymer insulating core  14  from a supply reel  37 . A plurality of conducting elements  12  are then wrapped around compressible insulating core  14  by a wire winding, wrapping or braiding unit  38  prior to passing the assembly through a heater  39 . From heater  39 , compressible insulating core  14  and plurality of conducting elements  12  are passed through the crosshead of an extruder  41 . A melt-extrudable fluoropolymer is fed into extruder  41  from a hopper  42 , and is shaped as a coaxial dielectric layer  29  around plurality of conducting elements  12 . Within extruder  41 , the fluoropolymer resin is heated above its melt temperature prior to extrusion as dielectric layer  29 . Cable-contact  30  is drawn through the process line by a capstan  43  and wound onto a take-up reel  44 . Cable-contact  30  is then unwound from take-up reel  44  and processed through cutting station  47  where it is cut transversely into individual contacts  5 . It will be understood that the cutting step exposes a second electrically accessible end of each of plurality of conducting elements  12  so as to allow for the use of each contact  5  as an electrical connection. Alternatively, a tape of dielectric material  29  may be wrapped around plurality of conducting elements  12  instead of being extruded.  
         [0050]    It will be understood that changing the shape, number, and rigidity of flexible conducting elements  12 , as well as, the shape and rigidity of the compressible insulating core  14 , outer shell  26 , layers  28  or  29 , the contact resistance, contact force, and compressibility can be selected within a wide range. Also, flexible conducting elements  12  are completely embedded in, and may be supported by, compressible outer shell  26  and layers  28 ,  29  since they are too fine and flexible to stand on their own. Alternatively, flexible conducting elements  12  may contribute significantly to the mechanical stability of contact  5 . The overall cumulative contact force of contacts  5  against the contact surfaces  40   a ,  40   b  of contact pads  31   a ,  31   b  is low due to the resilient construction and compressibility of contacts  5 , and is preferably in the range of approximately 20 to 40 grams per contact.  
         [0051]    Additionally, contacts  5  establish and maintain contact between each flexible conducting element  12  and its corresponding contact pads  31   a , 31   b  at a high localized contact force, sufficient to induce plastic yielding. Another factor in producing a low overall contact force is limiting the number of continuous flexible conducting elements  12  per unit surface area or volume of contact body. The number and conductivity, however, of flexible conducting elements  12  should be selected so as to produce a low total resistance, at a preselected characteristic impedance, for the connector system, preferably in the range of 10 milliohms or less per contact  5 . It will also be understood that the angle of each flexible conducting element  12  at the surface of flat surface of contact  5 , which is determined in the case of a winding or coil by the pitch, is a design parameter that bears a direct relation to the contact pressure required—the steeper (more vertical) the angle, the higher the force required.  
         [0052]    Referring to FIGS. 2 and 13, one of the important aspects of the high speed connector system of the present invention is the provision of a flexcircuit board-to-board interconnect system  50  which achieves a relatively high number of high data rate compatible electrical connections in a relatively small area, in a manner which does not substantially reduce or compromise the bandwidth of the signals conducted through the assembly of contacts  5 .  
         [0053]    In one embodiment of the invention, flexcircuit board-to-board interconnect system  50  comprises a plurality of contacts  5  mechanically and electrically engaged with a plurality of circuit traces  55  located in flexcircuit  10 . Each contact  5  is assembled to flexcircuit  10  such that one or more of its flexible conducting elements  12  is electrically connected to each respective trace  55  via contact pad  31   b , and its shielding layers  28  are electrically connected to a ground plane conductor  60 , via contact pad  31   a . It should be understood that contact pads  31   a ,  31   b  may be arranged so as to allow for a surface exit of trace  55  through a power or signal via  57  (FIGS.  12 - 16 ) or ground plane conductor  60  through a ground via  61 .  
         [0054]    In another embodiment of the invention, a housing block  18  may be employed comprising a variety of support structures that are suitable for arranging and supporting contacts  5 . The electrical and mechanical characteristics of connector system  2  may be optimized by careful selection of the material for housing block  18  based on such factors as cost, rigidity, thermal stability, and inertness to humidity and air and chemical impurities. Suitable materials for housing block  18  include polymers having a low and uniform dielectric constant, such as any of the well known dielectric, polymer materials that are suitable for injection molding, and are commonly used in the connector or semiconductor packaging industry, e.g., polyhalo-olefins, polyamides, polyolefins, polystyrenes, polyvinyls, polyacrylates, polymethacrylates, polyesters, polydienes, polyoxides, polyamides and polysulfides and their blends, co-polymers and substituted derivatives thereof.  
         [0055]    For example, housing block  18  may comprises a plurality of injection molded shells  75 , each having one or more internal receptacle guides  77  that are sized and shaped so as to receive an elongate contact  5 . In this way, a board-to-board connector  2  may be formed having a plurality of contacts  5  arranged so as to provide for either ninety degree or parallel positioning of the mated printed wiring boards. Alternatively, contacts  5  may be insert molded during the formation of housing block  18  to form a board-to-board connector  2 .  
         [0056]    Referring to FIG. 17, in a further embodiment of the present invention, a plurality of contacts  5  may be used as jumpers between printed wiring boards  36   a ,  36   b . In this embodiment, a plurality of contact pads  31   a ,  31   b  are arranged in an array on the surfaces of printed wiring boards  36   a  and  36   b , with first end  17  and second end  19  of each contact  5  electrically and mechanically engaged with a corresponding contact pad  31   a ,  31   b . It will be understood that conventional soldering or brazing methods may be used to facilitate the mechanical and electrical interconnection between contacts  5  and contact pads  31   a ,  31   b.    
         [0057]    Referring to FIG. 18, an interposer  80  may be formed having a plurality of contacts  5  arranged on one or both surfaces so as to provide an interconnection between a printed wiring board  36   a  and a microprocessor package  85  that is to be arranged on printed wiring board  36   a.    
         [0058]    It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.