Patent Publication Number: US-2022224034-A1

Title: Midboard cable termination assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/742,596, filed on Jan. 14, 2020, entitled “MIDBOARD CABLE TERMINATION ASSEMBLY,” which claims priority to and the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/850,381, filed on May 20, 2019, entitled “SMALL FORM FACTOR INTERPOSER,” as well as claims priority to and the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/792,232, filed on Jan. 14, 2019, entitled “MIDBOARD CABLE TERMINATION ASSEMBLY,” as well as claims priority to and the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/792,222, filed on Jan. 14, 2019, entitled “SMALL FORM FACTOR INTERPOSER.” The entire contents of these applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     This patent application relates generally to interconnection systems, such as those including electrical connectors, used to interconnect electronic assemblies. 
     Electrical connectors are used in many electronic systems. It is generally easier and more cost effective to manufacture a system as separate electronic assemblies, such as printed circuit boards (PCBs), which may be joined together with electrical connectors. A known arrangement for joining several printed circuit boards is to have one printed circuit board serve as a backplane. Other printed circuit boards, called “daughterboards” or “daughtercards,” may be connected through the backplane. 
     A backplane is a printed circuit board onto which many connectors may be mounted. Conducting traces in the backplane may be electrically connected to signal conductors in the connectors so that signals may be routed between the connectors. Daughtercards may also have connectors mounted thereon. The connectors mounted on a daughtercard may be plugged into the connectors mounted on the backplane. In this way, signals may be routed among the daughtercards through the backplane. The daughtercards may plug into the backplane at a right angle. The connectors used for these applications may therefore include a right angle bend and are often called “right angle connectors.” 
     Connectors may also be used in other configurations for interconnecting printed circuit boards. Sometimes, one or more smaller printed circuit boards may be connected to another larger printed circuit board. In such a configuration, the larger printed circuit board may be called a “motherboard” and the printed circuit boards connected to it may be called daughterboards. Also, boards of the same size or similar sizes may sometimes be aligned in parallel. Connectors used in these applications are often called “stacking connectors” or “mezzanine connectors.” 
     Connectors may also be used to enable signals to be routed to or from an electronic device. A connector, called an “I/O connector” may be mounted to a printed circuit board, usually at an edge of the printed circuit board. That connector may be configured to receive a plug at one end of a cable assembly, such that the cable is connected to the printed circuit board through the I/O connector. The other end of the cable assembly may be connected to another electronic device. 
     Cables have also been used to make connections within the same electronic device. The cables may be used to route signals from an I/O connector to a processor assembly that is located at the interior of printed circuit board, away from the edge at which the I/O connector is mounted. In other configurations, both ends of a cable may be connected to the same printed circuit board. The cables can be used to carry signals between components mounted to the printed circuit board near where each end of the cable connects to the printed circuit board. 
     Cables provide signal paths with high signal integrity, particularly for high frequency signals, such as those above 40 Gbps using an NRZ protocol. Cables are often terminated at their ends with electrical connectors that mate with corresponding connectors on the electronic devices, enabling quick interconnection of the electronic devices. Each cable has one or more signal conductors, which is surrounded by a dielectric material, which in turn is surrounded by a conductive layer. A protective jacket, often made of plastic, may surround these components. Additionally the jacket or other portions of the cable may include fibers or other structures for mechanical support. 
     One type of cable, referred to as a “twinax cable,” is constructed to support transmission of a differential signal and has a balanced pair of signal wires, is embedded in a dielectric, and encircled by a conductive layer. The conductive layer is usually formed using foil, such as aluminized Mylar. The twinax cable can also have a drain wire. Unlike a signal wire, which is generally surrounded by a dielectric, the drain wire may be uncoated so that it contacts the conductive layer at multiple points over the length of the cable. At an end of the cable, where the cable is to be terminated to a connector or other terminating structure, the protective jacket, dielectric and the foil may be removed, leaving portions of the signal wires and the drain wire exposed at the end of the cable. These wires may be attached to a terminating structure, such as a connector. The signal wires may be attached to conductive elements serving as mating contacts in the connector structure. The drain wire may be attached to a ground conductor in the terminating structure. In this way, any ground return path may be continued from the cable to the terminating structure. 
     SUMMARY 
     In some aspects, embodiments of a midboard cable termination assembly are described. 
     In some embodiments, a midboard cable termination assembly comprises a lid, a frame having a first surface and a second surface, and a paddle card disposed within the frame. The paddle card may comprise at least one conductive hole and at least one pad electrically connected to the at least one conductive hole in the paddle card. The at least one pad may be configured to electrically connect to a termination end of a cable. The lid may be operably coupled to the frame such that the lid may be moved into a position in which the lid applies a force on the paddle card, the force urging the paddle card towards the second surface of the frame. 
     In some embodiments, a midboard cable termination assembly comprises a frame a lid and an interposer. The frame may have a first surface and a second surface and a first alignment feature. The interposer may comprise a plurality of compressive contacts and a second alignment feature, shaped to engage the first alignment feature. The frame and lid may be configured to provide a space to receive a paddle card to which a plurality of cables are terminated. The lid may be operably coupled to the frame such that the lid may be moved into a position in which the lid applies a force on a paddle card in the space such that the paddle card presses against the interposer. 
     In some embodiments, a midboard cable termination assembly may be operated according to a method comprising: inserting a paddle card into a cable termination assembly attached to an interior portion of a printed circuit board having pads on a surface thereof and moving a lid of the cable termination assembly from an open to a closed position. The paddle card may have a first surface and a second, opposing surface, with a plurality of cables terminated to the first surface and, on the second surface, a plurality of conductive pads, electrically coupled through the paddle card to the cable terminations. The cable termination assembly may comprise an interposer comprising a plurality of compressive contacts each having a first end and a second end, electrically coupled to the first end. Moving the lid of the cable termination assembly from an open to a closed position may generate a force on the paddle card, pressing the pads on the second surface of the paddle card against the first ends of the compressive contacts of the interposer, such that the second ends of the compressive contacts are pressed against the pads on the surface of the printed circuit board. 
     In some aspects, embodiments of a small form factor interposer are described. 
     In some embodiments, an interposer may comprise a first plurality of electrical contacts comprising a corresponding first plurality of bases, each of the first plurality of bases comprising opposing edges and opposing broadsides connecting the opposing edges and a second plurality of electrical contacts including a corresponding second plurality of bases, each of the second plurality of bases comprising opposing edges and opposing broadsides connecting the opposing edges. The first plurality of bases and the second plurality of bases may be electrically coupled with broadsides of the first plurality of bases parallel to and aligned with broadsides of the second plurality of bases such that the first plurality of electrical contacts points away from the second plurality of electrical contacts. 
     In some embodiments, a method for manufacturing an interposer may comprise providing a first sheet of conductive metal and a second sheet of conductive metal and forming a first plurality of electrical contacts in the first sheet, wherein the first plurality of electrical contacts are distributed in the first sheet in a particular configuration. The method may further comprise forming a second plurality of electrical contacts in the second sheet, wherein the second plurality of electrical contacts are distributed in the second sheet in the particular configuration and mechanically and electrically coupling the first plurality of electrical contacts and the second plurality of electrical contacts such that the first plurality of electrical contacts points away from the second plurality of electrical contacts. 
     In some embodiments, an electronic assembly may comprise a first printed circuit board comprising a first surface and a first plurality of conductive pads thereon and a second printed circuit board comprising a second surface and a second plurality of conductive pads thereon, wherein the second surface faces the first surface. The electronic assembly may further comprise an interposer between the first printed circuit board and the second printed circuit board. The interposer may comprise an insulative member comprising a first surface facing the first surface of the first printed circuit board and a second surface facing the second surface of the second printed circuit board. The interposer may comprise a first plurality of contacts. Each contact of the first plurality of contacts may comprise a base portion within the insulative member and a beam portion extending from the insulative member beyond the first surface of the insulative member. Each contact of the first plurality of contacts may contact a pad of the first plurality of conductive pads. The interposer may comprise a second plurality of contacts. Each contact of the second plurality of contacts may comprise a base portion within the insulative member and a beam portion extending from the insulative member beyond the second surface of the insulative member and may contact a pad of the second plurality of conductive pads. The beam portions of the first plurality of contacts may be aligned, in a direction perpendicular to the first surface of the first printed circuit board, with the beam portions of the second plurality of contacts. 
     In some embodiments, an interposer may comprise a first plurality of electrical contacts comprising a corresponding first plurality of bases, each of the first plurality of bases comprising opposing edges and opposing broadsides connecting the opposing edges and a second plurality of electrical contacts including a corresponding second plurality of bases, each of the second plurality of bases comprising opposing edges and opposing broadsides connecting the opposing edges. The first plurality of bases and the second plurality of bases may be electrically coupled with broadsides of the first plurality of bases parallel to and offset from broadsides of the second plurality of bases such that the first plurality of electrical contacts points away from the second plurality of electrical contacts. 
     The foregoing features may be used separately or in any suitable combination. The foregoing is a non-limiting summary of the invention, which is defined by the attached claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
         FIG. 1  is an isometric view of an illustrative midboard cable termination assembly disposed on a printed circuit board, in accordance with some embodiments; 
         FIG. 2  is an isometric view of an illustrative midboard cable termination assembly in an open configuration, in accordance with some embodiments; 
         FIG. 3  is an isometric view of an illustrative midboard cable termination assembly in a closed configuration, in accordance with some embodiments; 
         FIG. 4  is a side view, partially exploded, of an illustrative midboard cable termination assembly in an open configuration, in accordance with some embodiments; 
         FIG. 5  is a side view, partially exploded, of an illustrative midboard cable termination assembly in a closed configuration, in accordance with some embodiments; 
         FIG. 6  is an isometric view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 7  is an enlarged view of a portion of an illustrative interposer, in accordance with some embodiments; 
         FIG. 8A  is a plan view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 8B  is an enlarged view of a portion of the illustrative interposer of  FIG. 8A  within box A, in accordance with some embodiments; 
         FIG. 9A  is a side view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 9B  is an enlarged view of the illustrative interposer of  FIG. 9A  within box B, in accordance with some embodiments; 
         FIG. 10A  is a cross section of portions of two sheets of metal in a stage of manufacture of an interposer according to some embodiments; 
         FIG. 10B  is a cross section of the portion of the interposer of  FIG. 10A  in a subsequent stage of manufacture; 
         FIG. 11  is an exploded isometric view, partially cut away, of components making electrical connection between a shield in a drainless cable and a paddle card, in accordance with some embodiments; 
         FIG. 12  is a perspective view of an illustrative midboard cable termination assembly in a partially assembled state, in accordance with some embodiments; 
         FIG. 13  is a side view, partially exploded, of an illustrative embodiment of an interposer, in accordance with some embodiments; 
         FIG. 14  is an isometric view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 15A  is an enlarged view of a portion of an illustrative interposer, in accordance with some embodiments; 
         FIG. 15B  is an enlarged view of a portion of an illustrative interposer, with an insulative housing shown partially transparent, in accordance with some embodiments; 
         FIG. 16A  is a plan view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 16B  is an enlarged view of a portion of the illustrative interposer of  FIG. 16A  within box A, in accordance with some embodiments; 
         FIG. 17A  is a side view of an illustrative interposer, in accordance with some embodiments; 
         FIG. 17B  is an enlarged view of the illustrative interposer of  FIG. 17A  within box B, in accordance with some embodiments; 
         FIG. 18  is a perspective view, of an illustrative midboard cable termination assembly in a partially assembled state, in accordance with some embodiments; and 
         FIG. 19  is a side cross-sectional view, of an interposer staked to a flexible printed circuit board, in accordance with some embodiments. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The inventors have recognized and appreciated techniques that enable electrical connections with high signal integrity to be made to locations at the interior of a printed circuit board. The inventors have also recognized and appreciated techniques for making a high density interposer. These techniques may be used separately or together, in any suitable combination. 
     High integrity connections may be made to the interior of a printed circuit board through a midboard cable termination assembly. Such a termination assembly may have a frame that positions a paddle card to which multiple cables may be terminated. The frame may also position an interposer such that, when the paddle card is positioned by the frame, it is also aligned with the interposer. The midboard cable termination assembly may have a lid, which is movable between an open and closed position. With the lid in the open position, the paddle card may be easily inserted into the frame. With the lid rotated or otherwise moved into the closed position, the lid applies force that urges the paddle card towards a lower surface of the frame such that the paddle card presses against the interposer. Resulting compression of the interposer makes electrical contact between pads on a lower surface of the paddle card and pads on an upper surface of a printed circuit board to which the midboard cable termination assembly is mounted. 
     The interposer may be thin and may have a high density of contacts making connection between the paddle card and the printed circuit board. In some embodiments, the interposer may have a thickness of less than 6 mm or less than 5 mm or less than 4 mm. In some embodiments, the interposer may have a thickness between 1 mm and 5 mm or between 2.5 mm and 4.5 mm, or, in some embodiments approximately 4 mm. The contacts may be spaced in rows with a contact pitch of less than 1 mm, such as between 0.4 mm and 0.7 mm. The rows may be spaced with an average spacing of less than 1.8 mm, in some embodiments, yielding a contact density on the order of 1 contact per mm 2 , such as between 1 and 3 contacts per mm 2 . Such an interposer may be suited for making a midboard cable termination assembly that has a height above a printed circuit to which the termination assembly is mounted of less than 6 mm. Such an interposer, however, may be used in any application in which a compact and high density interposer is beneficial. 
     A short and high density interposer may be achieved with contacts formed as two beams, joined at their bases. For example,  FIGS. 9A and 9B  show an illustrative interposer with contacts formed as two beams and joined at their bases. The bases may have broadsides and may be joined broadside to broadside. For example,  FIGS. 10A and 10B  shown an illustrative interposer where the bases have broadsides and are joined broadside to broadside. In some embodiments, the bases as joined may form a planar structure parallel to the surfaces to be electrically connected by the interposer. For example,  FIG. 6  shows an illustrative interposer where the bases as joined form a planar structure. The bases of the beams, for example, may be joined using laser welding or other suitable attachment technique. The joined bases may be fully or partially encapsulated in plastic or other dielectric materials to hold the contacts with a desired spacing. 
       FIG. 1  shows an isometric view  100  of an illustrative midboard cable termination assembly disposed on a printed circuit board, in accordance with some embodiments. In the illustrated example, the midboard cable termination assembly is used to provide a low loss path for routing electrical signals between one or more components, such as component  112 , mounted to printed circuit board  110  and a location off the printed circuit board. Component  112 , for example, may be a processor or other integrated circuit chip. However, any suitable component or components on printed circuit board  110  may receive or generate the signals that pass through the midboard cable termination assembly. 
     In the illustrated example, the midboard cable termination assembly couples signals between component  112  and printed circuit board  118 . Printed circuit board  118  is shown to be orthogonal to circuit board  110 . Such a configuration may occur in a telecommunications switch or other types of electronic equipment. However, a midboard cable termination assembly may be used to couple signals between a location in the interior of a printed circuit board and one or more other locations. 
       FIG. 1  shows a portion of an electronic system including midboard cable termination assembly  102 , cables  108 , component  112 , right angle connector  114 , connector  116 , and printed circuit boards (PCBs)  110 ,  118 . Midboard cable termination assembly  102  may be mounted on PCB  110  near component  112 , which is also mounted on PCB  110 . Midboard cable termination assembly  102  may be electrically connected to component  112  via traces in PCB  110 . Other suitable connections techniques, however, may be used instead of or in addition to traces in a PCB. In other embodiments, for example, midboard cable termination assembly  102  may be mounted to a component package containing a lead frame with multiple leads, such that signals may be coupled between midboard cable termination assembly  102  and the component through the leads. 
     Cables  108  may electrically connect midboard cable termination assembly  102  to a location remote from component  112  or otherwise remote from the location at which midboard cable termination assembly  102  is attached to PCB  110 . In the illustrated embodiment, a second end of cable  108  is connected to right angle connector  114 . Connector  114  is shown as an orthogonal connector that can make separable electrical connections to connector  116  mounted on a surface of printed circuit board  118  orthogonal to printed circuit board  110 . Connector  114 , however, may have any suitable function and configuration. 
     In the embodiment illustrated, connector  114  includes one type of connector units mounted to PCB  110  and another type of connector units terminating cables  108 . Such a configuration enables some signals routed through connector  114  to connector  116  to be connected to traces in PCB  110  and other signals to pass through cables  108 . In some embodiments, higher frequency signals, such as signals above 10 GHz or above 25 GHz in some embodiments, may be connected through cables  108 . 
     In the illustrated example, the midboard cable termination assembly  102  is electrically connected to connector  114 . However, the present disclosure is not limited in this regard. The midboard cable termination assembly  102  may be electrically connected to any suitable type of connector or component capable of accommodating and/or mating with the second ends  106  of cables  108 . 
     Cables  108  may have first ends  104  attached to midboard cable termination assembly  102  and second ends  106  attached to connector  114 . Cables  108  may have a length that enables midboard cable termination assembly  102  to be spaced from second ends  106  at connector  114  by a distance D. 
     In some embodiments, the distance D may be longer than the distance over which signals at the frequencies passed through cables  108  could propagate along traces within PCB  110  with acceptable losses. Any suitable value, however, may be selected for distance D. In some embodiments, D may be at least six inches, in the range of one to 20 inches, or any value within the range, such as between six and 20 inches. However, the upper limit of the range may depend on the size of PCB  110 , and the distance from midboard cable termination assembly  102  that components, such as component  112 , are mounted to PCB  110 . For example, component  112  may be a microchip or another suitable high-speed component that receives or generates signals that pass through cables  108 . 
     Midboard cable termination assembly  102  may be mounted near components, such as component  112 , that receive or generate signals that pass through cables  108 . As a specific example, midboard cable termination assembly  102  may be mounted within six inches of component  112 , and in some embodiments, within four inches of component  112  or within two inches of component  112 . Midboard cable termination assembly  102  may be mounted at any suitable location at the midboard, which may be regarded as the interior regions of PCB  110 , set back equal distances from the edges of PCB  110  so as to occupy less than 80% of the area of PCB  110 . 
     Midboard cable termination assembly  102  may be configured for mounting on PCB  110  in a manner that allows for ease of routing of signals coupled through connector  114 . For example, the footprint associated with mounting midboard cable termination assembly  102  may be spaced from the edge of PCB  110  such that traces may be routed out of that portion of the footprint in all directions, such as towards component  112 . In contrast, signals coupled through connector  114  into PCB  110  will be routed out of a footprint of connector  114  towards the midboard. 
     Further, connector  114  is attached with eight cables aligned in a column at second ends  106 . The column of cables are arranged in a 2×4 array at first ends  104  attached to midboard cable termination assembly  102 . Such a configuration, or another suitable configuration selected for midboard cable termination assembly  102 , may result in relatively short breakout regions that maintain signal integrity in connecting to an adjacent component in comparison to routing patterns that might be required were those same signals routed out of a larger footprint. 
     The inventors have recognized and appreciated that signal traces in printed circuit boards may not provide the signal density and/or signal integrity required for transmitting high speed signals, such as those of 25 GHz or higher, between high-speed components mounted in the midboard and connectors or other components at the periphery of the PCB. Instead, signal traces may be used to electrically connect a midboard cable termination assembly to a high-speed component at short distance, and in turn, the midboard cable termination assembly may be configured to receive termination ends of one or more cables carrying the signal over a large distance. Using such a configuration may allow for greater signal density and integrity to and from a high-speed component on the printed circuit board. 
       FIG. 2  shows isometric view  200  of an illustrative midboard cable termination assembly in an open configuration, in accordance with some embodiments. In the illustrated example,  FIG. 2  shows midboard cable termination assembly  102  having lid  202 , frame  204 , and paddle card  206  disposed within frame  204 . 
     Frame  204  may be held in place using hold downs  216 . Frame  204  may be attached in a particular location of PCB  110  or in any other suitable location through the use of hold downs. Hold downs  216  may be threaded holes that receive screws passing through PCB  110 . However, other types of hold downs may be used, such as posts that make an interference fit with holes in PCB  110  or compliant pins. As another example, hold downs  216  may include pads on a lower surface of frame  204  that may be soldered to pads on a PCB. 
     Lid  202  may be operable to move between an open and a closed position, such as, for example, by being connected to frame  204  via hinge  212 . Lid  202  may be coupled to the rest of midboard cable termination assembly such that lid  202  applies a force on paddle card  206  when closed. That force may urge paddle card  206  towards a surface of frame  204  facing a printed circuit board to which midboard cable termination assembly is mounted. Lid  202  may be operable to assert such a force due to movement of hinge  212 . However, the present disclosure is not limited in this regard. For example, lid  202  may be separate from frame  204  and secured to frame  204  with an attachment mechanism. Lid  202  may include projections  228  that align with the edges of paddle card  206 . Projections  228  may allow force to be applied on paddle card  206  from lid  202  without crushing any cables or cable terminations disposed on paddle card  206 . 
     Even if not a separate component, lid  202  may be held in the closed position with a releasable attachment mechanism. In the embodiment of  FIG. 2 , lid  202  may be held in a closed position with respect to frame  204  via one or more latches, which may be spring-biased. Lid  202  may apply a force on paddle card  206  when latched to frame  204 . In the embodiment of  FIG. 2 , lid  202  may be held in the closed position by latches  214 . Latches  214  may hold lid  202  in a position in which it exerts a force on paddle card  206  and may prevent lid  202  from opening due to forces generated by shock or vibration. 
     In the embodiment illustrated, latches  214  are integrally molded as part of frame  204 . Each of latches  214  has neck  222  that is sufficiently long and flexible that the latch will deflect away from the center of midboard cable termination assembly when a force perpendicular to an upper surface of frame  204  is applied to it. However, the neck will be sufficiently rigid that latch  214  will spring back to the position indicated when the force is removed. Latch  214  further includes head  224  with a tapered surface that is positioned to interfere with surface  226  of lid  202  when lid  202  is moved from an open to a closed position. Surface  226  of lid  202  and/or head  224  of latch  214  may be tapered, acting as a camming surface such that downward force on lid  202  is translated into a force that pushes head away from the center of midboard cable termination assembly. When surface  226  clears the head of latch  214 , that force is removed and latch  214  will spring back, engaging an upper surface of lid  202 , as shown in  FIG. 3 . However, the present disclosure is not limited in this regard. For example, a clamping member may be provided over midboard cable termination assembly  102  to retain the position of lid  202 . 
     Paddle card  206  may be constructed using techniques known for use in paddle cards of plug connectors, including multilayer PCB manufacturing techniques. Paddle card  206  may include conductive interconnects between an upper surface and a lower surface. Those conductive interconnects may be formed with conductive holes and, in some embodiments, conductive traces. Accordingly, paddle card  206  may have at least one conductive hole (not shown). 
     Pads  210  may be disposed on paddle card  206  such that pads  210  are electrically connected to the conductive holes in paddle card  206 . Pads  210  may be configured to terminate cables  108 . Lid  202  may be contoured to accommodate ends of cables  108  terminated to paddle card  206 . However, the present disclosure is not limited in this regard. For example, lid  202  may be composed of material or be may be lined on the inner surface with material that is compliant to accommodate the termination ends of cables  108 . 
     Each cable  108  may include one or more conductors. In some embodiments, each cable may have two signal wires and a shield surrounding the signal wires. In the illustrated embodiment, each cable  108  further includes a drain wire connected to the shield. Accordingly, cable  108  is illustrated as having a pair of signal wires  218 ,  220  and a drain wire. In some embodiments, cables  108  may include a twinax cable including signal wires  218 ,  220 , each covered by a dielectric coating. The twinax cable may further include a third, uncovered wire, the drain wire. Signal wires  218 ,  220  and the drain wire may be surrounded by a conductive layer configured to serve as an electric shield. The drain wire may electrically contact the conductive layer at multiple locations along the cable (not shown), thus maintaining a ground reference with the conductive layer. As illustrated in  FIG. 2 , the enclosing jacket and the conductive layer have been removed from the end of the cable to permit termination. 
     Paddle card  206  may include pads  210  in a spaced arrangement suitable for receiving multiple cables  108 . Paddle card  206  may include a grounding structure. When cables  108  are terminated at pads  210 , signal wires  218 ,  220  may form electrical contacts with the pads  210 . The shield and/or the drain may be attached to the grounding structure. For example, the grounding structure may contact the various drain wires, thus keeping the cables grounded. In the illustrated embodiment, the grounding structure is connected to additional pads on the upper surface of paddle card  206  and the drain wire is attached to such a pad. 
     However, other techniques to ground cables  108  may be used. Cable termination assemblies using a conductive, compliant member as part of a termination, as described below, enable use of cables without drain wires. Such cables may be lighter and more flexible than cables with drain wires. Moreover, the such cable termination assemblies may simplify terminating cables to paddle card  206 , as a drain wire would not have to be separated from the cable or attached to paddle card  206 . 
     In some embodiments, a conductive, compliant material may be positioned to make an electrical connection between a conductive layer of cable  108  and the grounding structure of paddle card  206 . To make such a connection, the insulating cover on the conductive layer may be removed at the end of the cable, exposing the conductive layer of cable  108 . 
     The conductive, compliant member may be mounted between the grounding portion of paddle card  206  and the conductive layer of cable  108 . The conductive, compliant material, for example, may partially or fully encircle cable  108  and also contact the grounding portion of paddle card  206 . Force may be generated by closing lid  202 , or in any other suitable way. The force may create a reliable electrical connection between the conductive layer of the cable  108  and the grounding portion of paddle card  206  via the conductive, compliant member. 
     When mounted between the conductive layer of cable  108  and the grounding portion of paddle card  206 , the conductive, compliant member may form a conducting path between those structures of less than 100 Ohms in some embodiments, less than 75 Ohms in some embodiments, less than 50 Ohms in some embodiments, less than 25 Ohms in some embodiments, less than 10 Ohms in some embodiments, less than 5 Ohms in some embodiments or less than 1 Ohm in some embodiments. When mounted between the conductive layer of the cable  108  and the grounding portion of paddle card  206 , the conductive, compliant member may form a conducting path between those structures of at least 0.5 Ohms in some embodiments, at least 1 Ohm in some embodiments, at least 5 Ohms in some embodiments, at least 10 Ohms in some embodiments, at least 25 Ohms in some embodiments or at least 50 Ohms in some embodiments. In such embodiments, the connection may be suitable for grounding. 
     In some embodiments, the conductive, compliant member may be a conductive elastomer. A conductive elastomer may be formed by adding conductive filler to an elastomer. In some embodiments, the elastomer may be configured to elongate by a percentage that is at least 90%. In some embodiments, the elastomer may be configured to elongate, without breaking, by a percentage that is less than 1120%. The elastomer, for example, may be a silicone rubber. The filler may be particles in any suitable form, including plates, spheres, fibers, or of any other suitable geometry. As a specific example, the conductive, compliant member may be made of silver-plated glass micro spheres suspended in high consistency rubber (HCR) silicone. 
     The material may be compliant as a result of a reduction in volume of the material under pressure. Material with this property may be created, for example, by creating open-celled foam within the material. Alternatively or additionally, the material may be made compliant as a result of flowing under pressure. 
     According to one aspect of the present application, the flexibility of the cables and the cost associated with the termination of the cables may be reduced by using electrical terminations comprising a conductive, compliant material in conjunction with a drainless cable.  FIG. 11  is an exploded view of a portion of a midboard cable termination assembly, in accordance with some embodiments. Cable termination  250  may comprise the end of a cable  252  and a conductive, compliant member  260 . Cable  252  may be terminated to a paddle card  282 , which may be used in a midboard cable termination assembly with a frame, lid and interposer as described elsewhere herein. 
     The opposite end of cable  252  may be configured to mate with another electronic device, such as a connector  116  described above. Cable  252  may have characteristics selected for the types of signals to pass between the connected devices. For example, cable  252  may comprise a pair of signal conductors  254  and  256 , which may be configured to carry a differential signal in some embodiments. Cable  252  may be configured to support signals having any suitable electric bandwidth, such as more than 20 GHz, more than 30 GHz or more than 40 GHz. 
     Paddle card  282  has on one surface pads  284 ,  286  and  288 . In the embodiment illustrated, pads  284  and  286  are signal pads. Those pads may be connected to signal pads on the opposing surface of paddle card  282  where they can be coupled, for example via an interposer as described herein to signal traces within a printed circuit board, such as PCB  110 , to which a midboard cable termination assembly may be mounted. Signal conductors  254  and  256  may be attached, such as by soldering, to pads  284  and  286 , respectively. 
     Pad  288  is here illustrated as a ground pad. Pad  288  may be connected to a ground pad on the opposing surface of paddle card  282  where it can be coupled, for example via an interposer as described herein, to ground layers within a printed circuit board, such as PCB  110 , to which a midboard cable termination assembly may be mounted. 
     In the embodiment illustrated, a shield layer of cable  252  is exposed in end region  290 , such as by stripping a portion of a polymer jacket (not numbered) from cable  252 . Here the connection between the exposed shield and the ground structure of the midboard cable termination assembly may be made through conductive, compliant member  260 . 
     In the embodiment illustrated, conductive, compliant member  260  fully surrounds cable  252 . As shown, conductive, compliant member  260  has a hole  262  through which end region  290  is inserted. Conductive, compliant member  260  is then positioned to surround end region  290  where it can make contact with the exposed shield layer. Conductive, compliant member  260  is also aligned with pad  288 . 
     Though not shown in  FIG. 11 , paddle card  282  may be held in a frame or otherwise supported in a midboard cable termination assembly. When lid  280  is moved into a closed position, it will exert a force on compliant member  260 . That force improves the electrical contact between conductive, compliant member  260  and both the exposed shield layer of cable  252  and pad  288 . In this way, a low resistance contact, such as 10 Ohms or less, and in some embodiments 5 Ohms or less, between the cable shield and the grounding structure of the midboard cable termination assembly is created. That termination may be created without the use of a drain wire. 
     It should be appreciated that  FIG. 11  illustrates a portion of a midboard cable termination assembly. The illustrated structure may be repeated for each of multiple cables terminated to a midboard cable termination assembly, such as the eight cables illustrated in  FIG. 2 . Moreover, when multiple cables are terminated, variations in components may be possible. For example, the same conductive, compliant member may fully or partially surround multiple cables, such as by producing one member with multiple holes. Alternatively, the compliant conductive member may be attached to another structure within the midboard cable termination assembly rather than fitted around a cable. For example, a filled elastomeric material might be deposited on pad  288  and/or cover  280 . Accordingly, it should be appreciated that  FIG. 11  illustrates just one exemplary approach for making an electrical connection between a cable shield and a ground structure with a midboard cable termination assembly. 
       FIG. 3  shows isometric view  300  of an illustrative midboard cable termination assembly in a closed configuration, in accordance with some embodiments. In the illustrated example,  FIG. 3  shows midboard cable termination assembly  102  in a state in which lid  202  is applying a force on paddle card  206 . In an embodiment, such as is shown in  FIG. 11 , in which there is one or more conductive, compliant member within the midboard cable termination assembly, closing the lid as illustrated in  FIG. 3  may alternatively or additionally exert force on those members. Frame  204  may have a first surface facing towards lid  202  and a second surface facing away from lid  202 , towards PCB  110  in the example of  FIG. 1 . The applied force may be sufficient to urge paddle card  206 , positioned within frame  204 , towards the second surface of frame  204 . Midboard cable termination assembly  102  may be configured such that urging paddle card  206  in this direction, which is toward a PCB to which the assembly is mounted, may create an electrical connection between one or more signal traces on the printed circuit board and conductive pads on a lower surface of paddle card  206 . Such an electrical connection may be created by springs or other type of compliant electrical contacts of an interposer (e.g., described with respect to  FIGS. 4-5 ), or another suitable electrical contact. 
     The inventors have recognized and appreciated that the housing of midboard cable termination assembly  102 , including lid  202  and frame  204 , may be rigid and add to the profile or thickness of the assembly. The thickness of the assembly can be a detriment in miniaturized electronic systems such as mobile consumer products or in high speed electronic assemblies where it is undesirable to have components mounted in the midboard region that can obstruct the flow of cooling air over the assembly or in a low profile enclosure, such as an enclosure of  1 U or less. This thickness is further exacerbated when using surface mount soldering, conductive adhesive, or another mounting solution that adds to the overall height of a top surface of the assembly. Mounting the assembly using a small form factor interposer, as described below, may reduce the profile or thickness of the mounted assembly. 
       FIG. 4  shows side view  400  of an illustrative midboard cable termination assembly, partially exploded, in an open configuration, in accordance with some embodiments. In the illustrated example,  FIG. 4  shows frame  204  separated from small form factor interposer  422 . Interposer  422  may include spring or compliant electrical contacts extending outward from the interposer. Electrical contacts  424  may extend toward midboard cable termination assembly  102 , and may be positioned to make contact with conductive pads on the lower surface of paddle card  206 . Electrical contacts  426  may extend away from midboard cable termination assembly  102 , and e.g., toward pads on a surface of printed circuit board to which the assembly is mounted such that electrical connections may be made to signal traces within the printed circuit board. Pairs of contacts extending in opposite directions from interposer  422  may be electrically connected within interposer  422  such that connections may be made between paddle card  206  and the printed circuit board. 
     Interposer  422  may include pillars  428  for orienting interposer  422  with respect to frame  204 . Pillars  428  may fit with one or more openings in frame  204  for alignment of interposer  422  and frame  204 . Additionally or alternatively, pillars  428  may hold interposer  422  within frame  204  such that once frame  204  is attached to a printed circuit board, such as through the hold downs  216 , interposer  422  may be captured between frame  204  and the printed circuit board. As interposer  422  is fixed with respect to frame  204 , paddle card  206  aligned within frame  204  will also be aligned with interposer  422  (and electrical contacts  424 ). Further details regarding interposer  422  are described with respect to  FIGS. 6-9  below. 
       FIG. 5  shows side view  500 , partially exploded, of an illustrative midboard cable termination assembly in a closed configuration, in accordance with some embodiments. Interposer  422  is shown exploded from frame  204 . In the illustrated example,  FIG. 5  shows the midboard cable termination assembly  102  having lid  202  apply a force towards the frame  204 . The frame  204  has a first surface facing towards the lid  202  and a second surface facing away from the lid  202 . Force exerted by lid  202  may urge paddle card  206 , disposed within frame  204 , towards the second surface of frame  204 . The applied force may be sufficient to urge the paddle card  206  towards the second surface such that the paddle card  206  may come in electrical contact with spring or compressive electrical contacts  424  of interposer  422 . That same force will press interposer  422  towards a surface of a printed circuit board to which midboard cable termination assembly  102  is mounted. As a results, contacts  426  are pressed into contact with pads on the surface of the printed circuit board. In such cases, interposer  422  may act as a dual compression connector, making connection between two pads on surfaces of two components without the use of solder. Within interposer  422 , contacts  424  are connected to contacts  426 . As a result, the electrical connections are made from cables  108 , through paddle card  206  and then through interposer  422  to a printed circuit board. 
     In some embodiments, the combined thickness or height, h, of the mounted interposer  422  may be low enough such that the resulting thickness is not a detriment for suitable applications, such as in miniaturized electronic systems, mobile consumer products, or another suitable applications. The height, h, from a top surface of midboard cable termination assembly  102  to a surface of the substrate on which interposer  422  is mounted, such as a printed circuit board, may be low, such as 5.55 mm in some embodiments, less than 10 mm in some embodiments, less than 5 mm in some embodiments, less than 2 mm in some embodiments, or within the range of 3.5 to 6 mm in some embodiments. 
     The inventors have recognized and appreciated techniques for manufacturing such low profile interposers that enable a high density of interconnections. In some interposers, both upwardly facing contacts  424  and downward facing contacts  426  may be formed from a single sheet of conductive metal. An upwardly facing contact and a downwardly facing contact, and a metal web joining them, may be stamped from the same sheet. However, the density of connections through the interposer is limited by the area of the material in the sheet that must be used to form both an upwardly facing contact and a downwardly facing contact and any material joining the two. The electrical contacts may at most be formed adjacent to one another in the single sheet such that their proximal ends are in electrical contact, but the distal ends of the electrical contacts cannot be aligned in a direction orthogonal to the surface of the sheet. Forming the interposer from two sheets of conductive metal, as described below, may allow for a small form factor due to high density of spring or compressive electrical contacts. Upwardly facing electrical contacts may be formed in the first sheet and downwardly facing contacts may be formed in the second sheet. The contacts may be electrically coupled such that the bases of the upwardly facing contacts are connected to the bases of the downwardly facing contacts. The contacts may be configured such that the distal ends of the upwardly facing and downwardly facing electrical contacts are aligned in a direction orthogonal to one or both surfaces of the interposer. In such a configuration, as the density is limited by the area of the sheet needed to form one contact rather than two, higher density of contacts is enabled. 
       FIG. 6  shows an isometric view of an illustrative interposer, in accordance with some embodiments. In the illustrated example, contacts of interposer  422  are made from two sheets of conductive, compliant material, such as aluminum, copper, or another suitable metal. In some embodiments, the sheet may be a metal alloy such as phosphor bronze or stainless steel, and/or may have layers of different materials, such as a copper alloy with a gold or silver plating. Electrical contacts  424  may be stamped from the first sheet of conductive metal such that they are distributed in a spaced configuration. Electrical contacts  426  may be stamped from the second sheet of conductive metal such that they are distributed in the same spaced configuration. 
     Electrical contacts  424  and electrical contacts  426  may be electrically coupled such that electrical contacts  424  point away from electrical contacts  426 . For example, the contacts may be bonded using a laser welding process, a conductive adhesive, or another suitable method. In some embodiments, the contacts may be metallurgically bonded. Such a bond may be formed between the contacts or may be the result of a braze of material coating the contacts. 
     When midboard cable termination assembly  102  is mounted on interposer  422 , electrical contacts  424  may point towards midboard cable termination assembly  102 , and at least a portion of electrical contacts  424  may be in electrical contact with pads on a surface of paddle board  206 . In the same example, electrical contacts  426  may point away from midboard cable termination assembly  102 , and e.g., toward pads on a printed circuit board, which may be coupled to signal traces within the printed circuit board. 
     Interposer  422  may include pillars  428  for orienting interposer  422  with respect to a mounting component, such as frame  204 . For example, pillars  428  may fit with one or more openings in frame  204  for alignment of interposer  422  and frame  204 . 
     Interposer  422  may have first surface  602 , from which electrical contacts  424  extend upwards (in a direction away from a surface of a printed circuit board to which the interposer is mounted, in this example), and second surface  604 , from where electrical contacts  426  extend downwards (in a direction toward a surface of a printed circuit board to which the interposer is mounted, in this example). Distal ends  606  of electrical contacts  424  and corresponding distal ends  608  of electrical contacts  426  may be aligned in a direction orthogonal to first surface  602  and second surface  604 . In the illustrated example shown in  FIG. 6 , electrical contacts  424  extend above first surface  602  and electrical contacts  426  extend below second surface  604 . In order to maintain the conductive electrical connection from, e.g., midboard cable termination assembly  102  to the printed circuit board substrate, proximal ends  610  of electrical contacts  424  are in electrical contact with corresponding proximal ends  612  of electrical contacts  426 . 
     In some embodiments, a small form factor interposer, such as interposer  422 , is manufactured from a first sheet of conductive, compliant material and a second sheet of conductive, compliant material, such as metal. A first set of electrical contacts, such as electrical contacts  424 , is stamped from the first sheet such that they are distributed in a particular pattern. A second set of electrical contacts, such as electrical contacts  426 , is stamped from the second sheet such that they are distributed in the same pattern. The first set of electrical contacts and the second set of electrical contacts are electrically coupled such that the first set of electrical contacts points away from the second set of electrical contacts. For example, contacts of the first sheet and contacts of the second sheet may be fused using a laser welding process, a conductive adhesive, or another suitable method.  FIGS. 10A and 10B  show two illustrative sheets of metal in different stages of manufacture of an interposer. 
       FIG. 7  shows enlarged view  700  of a portion of an illustrative interposer, in accordance with some embodiments. In the illustrated example, a portion of an interposer is shown. Electrical contact  702  and electrical contact  704  are positioned in the interposer such that their contact surfaces point away from each other. Electrical contact  702  may be formed from a first sheet of conductive metal, while electrical contact  704  may be formed from a second sheet of conductive metal. The proximal ends of electrical contact  702  and electrical contact  704  may be in electrical contact, and the distal ends of electrical contact  702  and electrical contact  704  may be aligned in a direction orthogonal to the surface of the first sheet and/or the second sheet. When in an interposer positioned adjacent the surface of a printed circuit board, they will also be aligned in a direction orthogonal to the surface of the printed circuit board. The two contacts together are above an area of the printed circuit board that is no greater than the area of a single one of the contacts. Such an arrangement using two sheets may allow for a higher density of electrical contacts to be formed compared to the density of electrical contacts formed in a single sheet, as described with respect to  FIG. 15 . 
       FIG. 8A  shows plan view  800  of an interposer, in accordance with some embodiments. The interposer includes electrical contacts and an insulative body partially or fully encapsulating bases of the electrical contacts to hold the electrical contacts with a desired spacing. The insulative body may also include one or more pillars for orienting the placement of the interposer with respect to a mounting component, such as frame  204 . For example, the pillars may fit with one or more openings in the mounting component for alignment of the interposer and the mounting component. In the illustrated example, interposer  422  has long edge  802  of length, a, and short edge  804  of length, b. The length, a, of long edge  802  is 13.70 mm in some embodiments, less than 20 mm in some embodiments, less than 15 mm in some embodiments, less than 10 mm in some embodiments, or less than 5 mm in some embodiments. The length, b, of short edge  804  is 7.68 mm in some embodiments, less than 15 mm in some embodiments, less than 10 mm in some embodiments, less than 5 mm in some embodiments, or less than 2 mm in some embodiments. Within this area, multiple rows of at least 10 contacts each may be formed. The rows, for example may have up to 12, 16 or 20 contacts in some embodiments. There may by at least 8 such rows. For example, there may be up to 10 rows, 12 rows or up to 16 rows, for example. 
       FIG. 8B  shows enlarged view  850  of a portion of the illustrative interposer of  FIG. 8A  within box A, in accordance with some embodiments. In the illustrated example, interposer  422  includes electrical contacts arranged in a configuration such that the space between electrical contact  852  and electrical contact  854 , adjacent to electrical contact  852 , is distance, c. The center-to-center distance, c, between electrical contact  852  and electrical contact  854  is 0.60 mm in some embodiments, less than 1 mm in some embodiments, less than 0.5 mm in some embodiments, or less than 0.2 mm in some embodiments. This spacing applies to both upwardly facing and downwardly facing contacts, as those contacts are aligned. 
       FIG. 9A  shows side view  900  of an illustrative interposer, in accordance with some embodiments. In the illustrated example, interposer  422  includes the spring or compressive electrical contacts and insulative body  902  partially or fully encapsulating bases of the electrical contacts to hold the electrical contacts with a desired spacing. Insulative body  902  includes pillars  428  for orienting the placement of interposer  422  with respect to a mounting component, such as frame  204 . Insulative body  902  has a thickness, d (excluding any further thickness due to pillars  428 ). The thickness, d, of insulative body  902  may be less than 1 mm in some embodiments, less than 0.5 mm in some embodiments, less than 0.2 mm in some embodiments, or less than 0.1 mm in some embodiments. As a specific example, the thickness may be approximately 0.40 mm in some embodiments. 
       FIG. 9B  shows enlarged view  950  of the illustrative interposer of  FIG. 9A  within box B, in accordance with some embodiments. In the illustrated example, interposer  422  includes electrical contacts arranged in a configuration such that the space between electrical contacts  952  and electrical contacts  954 , opposite to electrical contacts  952 , is distance, w. The distance, w, between electrical contacts  952  and electrical contacts  954  is 1.00 mm in some embodiments, less than 3 mm in some embodiments, less than 2 mm in some embodiments, less than 1 mm in some embodiments, or less than 0.5 mm in some embodiments. In some embodiments, the distance w may not be limited by the construction techniques of the interposer, but may, instead, be based on the spacing of pads of the adjacent rows of contact pads on a printed circuit board to which the interposer makes contact. 
       FIGS. 10A and 10B  illustrate a process of manufacturing an interposer.  FIG. 10A  is a cross section of portions of two sheets of metal  1010 ,  1020  in a stage of manufacture of an interposer according to some embodiments. In the configuration shown, upwardly facing contacts  1016  have been stamped from first sheet  1010  and downwardly facing contacts  1018  have been stamped from second sheet  1020 . For each of first sheet  1010  and second sheet  1020 , portions of the sheet may be left behind after the stamping, creating tie bars  1012 ,  1014 . Tie bars  1012 ,  1014  may hold contacts of the first sheet and of the second sheet, respectively, together with the desired orientation. 
     Contacts  1016 ,  1018  may be electrically coupled such that the bases of upwardly facing contacts  1016  are connected to the bases of downwardly facing contacts  1018 . The bases may have broadsides and may be joined broadside to broadside. For example, the bases of contacts  1016 ,  1018  may be bonded using a laser welding process, a conductive adhesive, or another suitable method. In some embodiments, the contacts may be metallurgically bonded. Such a bond may be formed between the contacts or may be the result of a braze of material coating the contacts. Contacts  1016 ,  1018  may be configured such that the distal ends of upwardly facing contacts  1016  and downwardly facing contacts  1018  are aligned in a direction orthogonal to one or both surfaces of the interposer. As the density is limited by the amount of material to form one contact in a sheet, higher density of contacts is enabled. 
       FIG. 10B  is a cross section of the portion of the interposer of  FIG. 10A  in a subsequent stage of manufacture. The joined bases of contacts  1016 ,  1018  may be fully or partially encapsulated in plastic or other dielectric materials to hold contacts  1016 ,  1018  with a desired spacing. For example, the joined bases of contacts  1016 ,  1018  may be overmolded with an insulative material  1030 . 
     Subsequently, tie bars  1012 ,  1014  may be cut away.  FIG. 10B  shows a cross section between two adjacent rows of contacts. The tie bars  1012  and  1014  joining those rows are shown cut away. Tie bars joining the contacts in the same rows are similarly cut away such that each contact pair, containing one upwardly facing and one downwardly facing contact, is electrically isolated from other contact pairs within the interposer. In some embodiments, spring force generated by the cantilevered shape of the contacts can generate the required force for making electrical contact with a pad pressed against the interposer, such as when a pad of a paddle card in a midboard cable termination assembly is pressed into the interposer or the interposer is pressed onto a printed circuit board with pads. Such an interposer may have a shorter vertical height than a design in which a single piece of metal is bent to form both the upwardly facing and downwardly facing contacts and deflection of the web between upper and lower contacts generates contact force. The interposer, for example may have a height on the order of 4 mm, or any other heights as described herein. 
     The density of connections through the interposer may be greater than in conventional interposers. Forming the interposer from two sheets of conductive metal, as described, may allow for a small form factor due to high density of spring or compressive electrical contacts. As the density is limited by the amount of material to form one contact in a sheet, higher density of contacts is enabled. 
     An interposer as described above may be used in other ways to make connections to the midboard of a printed circuit board. Moreover, interposers of other configurations may be used for making connections between conductive pads on surfaces of components, including in such midboard cable termination assemblies. 
       FIG. 12  shows a side view  1200  of an illustrative midboard termination assembly, partially exploded, in accordance with some embodiments.  FIG. 13  is a side view of an embodiment of an interposer  1222  that may be used in the assembly of  FIG. 12  or any other suitable application. 
     In the illustrated example of  FIG. 12 , signals may be routed to or from a midboard portion of printed circuit board  1210  using a flexible printed circuit board  1208 . In contrast to printed circuit board  1210 , which may be a rigid printed circuit board with conductive traces held within a rigid matrix, flexible printed circuit board  1208  may have signal traces held in or disposed on a flexible substrate, such as a polyimide film. Interposer  1222  is shown between rigid printed circuit board  1210  and flexible printed circuit board  1208 . Mechanical components may press rigid printed circuit board  1210  and flexible printed circuit board  1208  together, compressing electrical contacts of interposer  1222  against pads on the surfaces of each of rigid printed circuit board  1210  and flexible printed circuit board  1208 , acting as a dual compression connector between those components. 
     In the embodiment, illustrated, a force pressing rigid printed circuit board  1210  and flexible printed circuit board  1208  together may be generated by components such as bolt  1202  and nut  1212 . When the midboard termination assembly is assembled, interposer  1222  is aligned with pads on an upper surface of printed circuit board  1210  and pads on a lower surface of flexible printed circuit board  1208 . A plate  1204 , which may be made of a rigid material such as metal, may overlay the end of flexible printed circuit board  1208  aligned with interposer  1222 . A hole may pass through plate  1204 , flexible printed circuit board  1208 , interposer  1222  and printed circuit board  1210 . Bolt  1202  may pass through that hole and nut  1212  may be attached to bolt  1202  at the lower surface of printed circuit board  1210 . 
     Tightening nut  1212  onto bolt  1202  generates compressive force that completes electrical connections between printed circuit board  1210  and pads and flexible printed circuit board  1208 . In the illustrated embodiment, a compliant underlayment  1206  may be between flexible printed circuit board  1208  and plate  1204 . Compliant underlayment  1206  may accommodate variations in thickness of either flexible printed circuit board  1208  or plate  1204 , so as to avoid localized regions of high pressure when nut  1212  is tightened. 
       FIG. 13  illustrates an embodiment of interposer  1222 . Interposer  1222  is shown with compliant electrical contacts extending from opposing surfaces of the interposer. Electrical contacts  1224  extend from an upper surface. In the embodiment of  FIG. 12 , electrical contacts  1224  may extend towards pads on flexible printed circuit board  1208 . Electrical contacts  1226  may extend from a lower surface of interposer  1222 . In the embodiment of  FIG. 12 , they extend toward pads on a surface of printed circuit board  1210  to which the assembly is mounted such that electrical connections may be made to signal traces within the printed circuit board. Pairs of contacts extending in opposite directions from interposer  1222  may be electrically connected within interposer  1222  such that connections may be made between flexible printed circuit board  1208 , and printed circuit board  1210 , which is here a rigid printed circuit board. 
     Interposer  1222  may include pillars  1228  for orienting interposer  1222  with respect to flexible printed circuit board  1208 . It should be appreciated that pillars or other alignment features may alternatively or additionally extend from a lower surface of interposer  1222  to align interposer  1222  with printed circuit board  1210 . Pillars  1228  may fit within or pass through one or more openings in flexible printed circuit board  1208  for alignment of interposer  1222  and flexible printed circuit board  1208 . 
     Interposers, as described herein, provide for compact midboard termination assemblies. The height from a top surface of plate  1204  to a surface of the substrate on which interposer  1222  is mounted, such as a printed circuit board  1210 , may be low, such as 5.55 mm in some embodiments, less than 10 mm in some embodiments, less than 5 mm in some embodiments, less than 2 mm in some embodiments, or within the range of 3.5 to 6 mm in some embodiments. Dual compression connectors, which may be attached without solder, which entails high heat that could distort components, enable components with such small dimensions to be used reliably. Further details regarding interposer  1222  are described with respect to  FIGS. 14-17  below. 
     The inventors have recognized and appreciated techniques for manufacturing such low profile interposers as illustrated in  FIG. 12 . In some interposers, both upwardly facing contacts  1224  and downward facing contacts  1226  may be formed from a single sheet of conductive metal. Therefore an upwardly facing contact and a downwardly facing contact, and a metal web joining them, may be stamped from the same sheet. The electrical contacts may be formed adjacent to one another in the single sheet such that their proximal ends are electrically connected and may also be mechanically connected. 
       FIG. 14  shows an isometric view of interposer  1222 , in accordance with some embodiments. In the illustrated example, contacts of interposer  1222  are made from a sheet of conductive, compliant material, such as a metal that is suitably conductive and compliant. In some embodiments, the sheet may be a metal alloy such as phosphor bronze or stainless steel, and/or may have layers of different materials, such as a copper alloy with a gold or silver plating. Electrical contacts  1224  and electrical contacts  1226  may be stamped from the sheet of conductive metal such that they are distributed in a spaced configuration. Electrical contacts  1224  and electrical contacts  1226  may be electrically coupled such that electrical contacts  1224  point away from electrical contacts  1226 . 
     Interposer  1222  may include structures, here shown as pillars  1228 , for orienting interposer  1222  with respect to another component, such as flexible printed circuit board  1208 . For example, pillars  1228  may fit with one or more openings in flexible printed circuit board  1208  for alignment of interposer  1222  with conductive pads on flexible printed circuit board  1208 . 
     Interposer  1222  may have first surface  1402 , from which electrical contacts  1224  extend upwards (in a direction away from a surface of a printed circuit board  1210  to which the interposer is mounted, in the example of  FIG. 12 ), and second surface  1404 , from where electrical contacts  1226  extend downwards (in a direction toward a surface of a printed circuit board  1210  to which the interposer is mounted, in the example of  FIG. 12 ). Distal ends  1406  of electrical contacts  1224  and corresponding distal ends  1408  of electrical contacts  1226  may be offset in a direction orthogonal to first surface  1402  and second surface  1404 . In the illustrated example shown in  FIG. 14 , which shows an uncompressed state of interposer  1222 , electrical contacts  1224  extend above first surface  1402  and electrical contacts  1226  extend below second surface  1404 . In order to make a conductive electrical connection from, e.g., flexible printed circuit board  1208  to the printed circuit board  1210 , proximal ends  1410  of electrical contacts  1224  are in electrical contact with corresponding proximal ends  1412  of electrical contacts  1226 . 
     In some embodiments, a small form factor interposer, such as interposer  1222 , is manufactured from a single sheet of conductive, compliant material, such as metal. An upwardly facing set of electrical contacts and a downwardly facing set of electrical contacts, and a metal web joining them, may be stamped from the same sheet. A first set of electrical contacts, such as electrical contacts  1224 , and a second set of electrical contacts, such as electrical contacts  1226 , are stamped from the sheet such that they are distributed in a pattern. The first set of electrical contacts and the second set of electrical contacts may be formed adjacent to one another in the single sheet such that their proximal ends are in electrical and mechanical contact. The first set of electrical contacts and the second set of electrical contacts are electrically coupled such that the first set of electrical contacts points away from the second set of electrical contacts. 
       FIG. 15A  shows an enlarged view  1500  of a portion of interposer  1222 , in accordance with some embodiments. Electrical contact  1502  may be an upwardly facing contact  1224  and electrical contact  1504  may be a downwardly facing contact  1226  that are formed in the interposer such that they are electrically and mechanically connected. Electrical contact  1502  and electrical contact  1504  may be formed from a single sheet of conductive metal such that electrical contact  1502  and electrical contact  1504  are formed adjacent to each other. When cut from that sheet, electrical contact  1502  and electrical contact  1504  may remain joined by a web. While the proximal ends of electrical contact  1502  and electrical contact  1504  may be in electrical contact through that web, the distal ends of electrical contact  1502  and electrical contact  1504  are offset in a direction orthogonal to the surface of the single sheet. In some embodiments, such an arrangement using a single sheet may result in a lower density of electrical contacts compared to the density of electrical contacts formed using two sheets, as described with respect to  FIG. 7 , because one connection between a paddle card and a printed circuit board requires an area of the sheet at least as large as contacts  1502  and  1504  together—which is about twice the area for the configuration in  FIG. 7 . However, the area may nonetheless be suitably small for many electronic systems. 
     In  FIG. 15B , the insulative body of the interposer is shown transparent, revealing further structure of the contacts, including a web  1510  electrically and mechanically connecting an upward facing contact and a downward facing contact. 
       FIG. 16A  shows a plan view of interposer  1222 , in accordance with some embodiments. The interposer includes electrical contacts and an insulative body partially or fully encapsulating bases of the electrical contacts to hold the electrical contacts with a desired spacing. The insulative body may also include one or more pillars for orienting the placement of the interposer with respect to another component, such as frame  204  or flexible printed circuit board  1208 . 
     In the illustrated example, interposer  1222  has long edge  1602  of length, a, and short edge  1604  of length, b. The length, a, of long edge  1602  is 13.70 mm in some embodiments, less than 20 mm in some embodiments, less than 15 mm in some embodiments, less than 10 mm in some embodiments, or less than 5 mm in some embodiments. The length, b, of short edge  1604  is 7.68 mm in some embodiments, less than 15 mm in some embodiments, less than 10 mm in some embodiments, less than 5 mm in some embodiments, or less than 2 mm in some embodiments. Within this area, multiple rows of at least 10 contacts each may be formed. The rows, for example may have up to 12, 16 or 20 contacts in some embodiments. There may by at least 8 such rows. For example, there may be up to 10 rows, 12 rows or up to 16 rows, for example. 
       FIG. 16B  shows an enlarged view  1650  of a portion of the illustrative interposer of  FIG. 16A  within box A, in accordance with some embodiments. Electrical contact  1656  may be a downwardly facing contact  1226 . Electrical contacts  1652  and  1654  may be upwardly facing contact  1224 . Side-by-side upwardly facing and downwardly facing contacts, such as contacts  1654  and  1656  may be electrically and mechanically connected. In the illustrated example, interposer  1222  includes electrical contacts arranged in a configuration such that the spacing between electrical contact  1652  and electrical contact  1654 , adjacent to electrical contact  1652 , is distance, c. The center-to-center distance, c, between electrical contact  1652  and electrical contact  1654  may be 0.60 mm in some embodiments, less than 1 mm in some embodiments, less than 0.5 mm in some embodiments, or less than 0.2 mm in some embodiments. This spacing applies to both upwardly facing and downwardly facing contacts. 
     In the embodiment illustrated, the upwardly facing contacts are aligned in rows and the downwardly facing contacts may be aligned in parallel rows. The rows, however, may be offset in a direction along edge  1602 . Electrical contact  1654  and electrical contact  1656  are also offset in a direction orthogonal to the surface of interposer  1222  by an offset distance, f. The offset distance, f, between electrical contact  1654  and electrical contact  1656  is 0.27 mm in some embodiments, less than 0.5 mm in some embodiments, less than 0.2 mm in some embodiments, or less than 0.1 mm in some embodiments. In some embodiments, the center-to-center distance c and/or the offset distance f may be determined to maintain a compatible footprint and/or work mechanically with a midboard cable termination assembly or another suitable component disposed on the printed circuit board. 
       FIG. 17A  shows a side view of interposer  1222 , in accordance with some embodiments. In the illustrated example, interposer  1222  includes spring or compressive electrical contacts and insulative body  1702  partially or fully encapsulating bases of the electrical contacts to hold the electrical contacts with a desired spacing. Insulative body  1702  includes pillars  1228 . Insulative body  1702  has a thickness, d (excluding any further thickness due to pillars  1228 ). The thickness, d, of insulative body  1702  may be less than 1 mm in some embodiments, less than 0.5 mm in some embodiments, less than 0.2 mm in some embodiments, or less than 0.1 mm in some embodiments. As a specific example, the thickness may be approximately 0.40 mm in some embodiments. 
       FIG. 17B  shows an enlarged view  1750  of the interposer of  FIG. 17A  within box B, in accordance with some embodiments. In the illustrated example, interposer  1222  includes electrical contacts arranged in a configuration such that the space between upwardly facing electrical contact  1752  and upwardly facing electrical contact  1754 , opposite to electrical contact  1752 , is distance, w. The distance, w, between electrical contact  1752  and electrical contact  1754  is 1.00 mm in some embodiments, less than 3 mm in some embodiments, less than 2 mm in some embodiments, less than 1 mm in some embodiments, or less than 0.5 mm in some embodiments. 
     The distance, in a direction parallel to surfaces  1402  and  1404 , between the contact surface of an upwardly facing electrical contact  1754  and an adjacent downwardly facing electrical contact  1756  is distance, g. The distance, g, between electrical contact  1754  and electrical contact  1756  is 0.33 mm in some embodiments, less than 0.5 mm in some embodiments, less than 0.2 mm in some embodiments, or less than 0.1 mm in some embodiments. In some embodiments, an elongated member of the insulative body  1702 , in which the bases of electrical contacts and the webs joining them are embedded may have castellations  1512  ( FIG. 15A ). The castellations may have a length, which may also be g, that ensures that the amount of the base of each electrical contact embedded within the insulative body is close enough to being equal that the spring force generated by each electrical contact is equivalent. 
     In some embodiments, the distance w and/or the distance g may not be limited by the construction techniques of the interposer, but may, instead, be based on the spacing of pads of the adjacent rows of contact pads on a printed circuit board to which the interposer makes contact. In some embodiments, the distance w and/or the distance g may be determined to maintain a compatible footprint and/or work mechanically with a midboard termination assembly or another suitable component disposed on the printed circuit board. 
     In the pictured embodiments, interposer  1222  may not need to be mounted on either a flexible or rigid printed circuit board using surface-mount or similar technology. In some embodiments, interposer  1222  may be attached to either using a staking process.  FIG. 18  illustrates an embodiment in which interposer  1222  is mechanically attached to flexible printed circuit board  1208 , forming a cable assembly. That cable assembly may then be pressed against a printed circuit board  1210 , using mechanical components, such as bolt  1202  and nut  1212  described above in connection with  FIG. 12 . That mechanical force can compress electrical contacts on opposing surfaces of interposer  1222  into both flexible printed circuit board  1208  and printed circuit board  1210 . 
     Printed circuit board  1210  may include a connector footprint  1820  on its surface for this purpose. Footprint  1820  includes multiple parallel rows  1822  of conductive pads that make connections to traces or other conductive structures within printed circuit board  1210 . The pads may be positioned with the same spacing as the downward facing electrical contacts of interposer  1222 . The pads may be spaced with respect to hole  1824  such that, when interposer  1222  is held to printed circuit board  1210  with bolt  1202 , the downward facing electrical contacts of interposer  1222  will press against the pads. 
     Pillars  1228  may align interposer  1222  with flexible printed circuit board  1208  such that upward facing electrical contacts  1224  of interposer  1222  contact pads  1910  ( FIG. 19 ) on flexible printed circuit board  1208 . Pillars  1228  may pass through holes  1810  for alignment and/or mechanical attachment of interposer  1222  and flexible printed circuit board  1208 . The tops of pillars  1228  may then be modified to prevent them from being withdrawn through holes  1810 , thereby securing interposer  1222  to flexible printed circuit board  1208 . 
       FIG. 19  illustrates, in cross section, an embodiment in which a staking process alters the tops of pillars  1228  to hold pillars  1228  within holes  1810 . The tops have pancaked portions  1920  that are larger than holes  1810 . In embodiments in which the insulative body of interposer  1222  is formed of a thermoplastic material, pancaked portions  1920  may be formed by applying sufficient heat to the tops of pillars  1228  to soften the pillars, allowing them to be deformed. A heated tool pressed against pillars  1228  may modify the shapes of pillars  1228  to be as shown without applying so much heat to interposer  1222  that other portions of the insulative body deform, which might occur in a solder reflow operation. Thus, a staking process as illustrated may enable a very thin interposer with less risk of deformation during solder reflow. 
       FIG. 19  shows that, even after pillars  1228  have been modified with pancaked portions  1920 , they may be of sufficient length that flexible printed circuit board  1208  may slide up and down the pillars, allowing “float” in the direction F. In this way, upward facing electrical contacts  1224  need not be compressed upon attachment of interposer  1222  to flexible printed circuit board  1208 . Rather, compression may occur when the cable assembly, including flexible printed circuit board  1208  and interposer  1222  are attached to a printed circuit board  1210 , such as by bolt  1202  passing through both hole  1812  ( FIG. 18 ) in flexible printed circuit board  1208  and hole  1824  in rigid printed circuit board  1210 . 
     Having thus described several embodiments, it is to be appreciated various alterations, modifications, and improvements may readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. 
     For example,  FIG. 1  illustrates an electronic device in which a midboard cable termination assembly might be used. It should be appreciated that  FIG. 1  shows a portion of such a device. For example, board  110  may be larger than illustrated and may contain more components than illustrated. Likewise, board  118  may be larger than illustrated and may contain components. Moreover, multiple boards parallel to board  118  and/or parallel to board  110  may be included in the device. 
     A midboard cable termination assembly might also be used with board configurations other than the illustrated orthogonal configuration. The midboard cable termination assembly might be used on a printed circuit board connected to another, parallel printed circuit board or might be used in a daughter card that plugs into a backplane at a right angle. As yet another example, the midboard cable termination assembly might be mounted on a backplane. 
     As yet another example of a possible variation, a midboard cable termination assembly mounted on board  110  is shown with a cable that connects to a connector that is similarly mounted to board  110 . That configuration is not, however, a requirement, as the cable may be connected directly to the board, an integrated circuit or other component, even directly to the board  110  to which the midboard cable termination assembly is mounted. As another variation, the cable may be terminated to a different printed circuit board or other substrate. For example, a cable extending from a midboard cable termination assembly mounted to board  110  may be terminated, through a connector or otherwise, to a printed circuit board parallel to board  110 . 
     As yet another example, a paddle card is described as forming a portion of the midboard cable termination assembly. A paddle card may be formed using known printed circuit board manufacturing technology. However, other approaches for forming a suitable structure may be used. A set of leads may stamped from a sheet of metal. Each lead may have a conductive region to which a wire of a cable may be terminated. Another region may be shaped as a pad to make contact with a compliant contact of an interposer. The leads may be held together with plastic molded around them. The plastic may provide surfaces, with the regions for cable on surfaces facing in one direction and pads for contact with an interposer on surfaces facing in another direction. 
     Further, exemplary materials were described for components of the midboard cable termination assembly. Other materials may be used. For example, the frame and lid of the midboard cable termination assembly may be made of insulative material, such as plastic. Alternatively, some or all of the components may be conductive. The lid, for example, may be conductive and connected to ground so as to provide shielding for the cable terminations. Likewise, the frame may be made conductive and grounded to provide shielding or may be surrounded by a shielding cage. 
     Also, connections between a cable shield and the ground structure of the midboard cable termination assembly were described to be made via a pad on a surface of the paddle card. In other embodiments, connections may be made to other conductive portions of the assembly. 
     Further, a thin and high density interposer was described as used in a midboard cable termination assembly. Such an interposer is suitable for other uses. It may be used, for example, to connect a packaged semiconductor device or any other electronic component to a printed circuit board. In such a configuration, a semiconductor device with a Ball Grid Array or Land Grid Array may be connected to the board through the interposer. Alternatively or additionally, the component may be the end of a flexible printed circuit. Accordingly, it should be appreciated that a component with a substrate having contact pads thereon may be pressed against the interposer to make electrical connections. 
     Further, it is described that compressive force is applied to an interposer as a result of a lid being closed with some mechanism to bias the lid towards the interposer. That mechanism was described as spring-like members with camming surfaces formed as part of the frame. Similar spring-like members may be formed as part of a sheet-metal shell surrounding the frame and/or the interposer. 
     Moreover, as described, the lid was mechanically coupled to a frame that was secured to a printed circuit board. In alternative embodiments, the interposer may be secured to the printed circuit board directly, without a frame. For example, a screw may pass through the interposer, and one or both of the components connected by the interposer. Rotating the screw may draw those two components together, creating the compressive force on the interposer that electrically connects the components. 
     Terms signifying direction, such as “upwards” and “downwards,” were used in connection with some embodiments. These terms were used to signify direction based on the orientation of components illustrated or connection to another component, such as a surface of a printed circuit board to which a termination assembly is mounted. It should be understood that electronic components may be used in any suitable orientation. Accordingly, terms of direction should be understood to be relative, rather than fixed to a coordinate system perceived as unchanging, such as the earth&#39;s surface. 
     Further, though advantages of the present invention are indicated, it should be appreciated that not every embodiment of the invention will include every described advantage. Some embodiments may not implement any features described as advantageous herein and in some instances. Accordingly, the foregoing description and drawings are by way of example only. 
     Various aspects of the present invention may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. 
     Also, the invention may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. 
     Also, circuits and modules depicted and described may be reordered in any order, and signals may be provided to enable reordering accordingly. 
     Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     Also, the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof herein, is meant to encompass the items listed thereafter (or equivalents thereof) and/or as additional items.