An apparatus for terminating a controlled-impedance cable using compliant electrical contacts to provide an interface to another device. The terminator includes a conductive ground block for securing the cable by its ground shield and providing a common ground. Once the cable is anchored in the ground block, the block face and cable ends are dressed to make a reliable electrical contact with the compliant signal contact that electrically connects the cable center conductor to the device. An insulating or conductive plate mounted to the ground block holds the signal contact and optional ground contacts that electrically connect the ground block to the ground plane of the device. The ground contacts surround the signal contact in a pattern that closely mimics the impedance environment of the cable. When using a conductive plate, the signal contact is insulated from the plate by an insulating centering plug or a non-conductive coating. A controlled-impedance cable terminator using compliant electrical contacts to provide an interface to another device. The terminator includes a conductive plate with a face surface and a device surface. signal through holes extend between the face surface and device surface. Each signal through hole has an insulating centering plug with a signal through aperture that has openings in the face surface and the device surface. The signal through aperture holds a skewed coil signal contact with contact points extending from each signal through aperture opening. Optionally, the plate includes ground through apertures that surround the signal through aperture. Each ground through aperture has openings in the face surface and device surface. The ground through aperture holds a skewed coil ground contact with contact points extending from each ground through aperture opening.
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0. 10. A controlled-impedance cable termination adapter comprising:
(a) a plate composed of an electrically-conductive material and having a face surface and a device surface;
(b) at least one signal through hole in the plate extending between the face surface and the device surface;
(c) an insulating plug within each of the at least one signal through hole, the insulating plug extending between the face surface and the device surface and having a signal through aperture with a signal block opening in the face surface and a signal device opening in the device surface; and
(d) an electrically-conductive compliant skewed coil signal contact captured within each of the at least one signal through aperture, the signal contact having a signal block contact point extending from the signal block opening and a signal device contact point extending from the signal device opening.
0. 1. A controlled-impedance cable termination comprising:
(a) a ground block composed of an electrically conductive material, said block having a face, at least one cable through hole adapted to receive a controlled-impedance cable, said cable hole having an opening in said face;
(b) a plate attached to said face, said plate having a face surface abutting said face and a device surface, said plate including at least one signal through aperture extending between said face surface and said device surface, said signal aperture having a signal block opening adjacent to and aligned with said cable hole opening, said signal aperture having a signal device opening in said device face; and
(c) an electrically-conductive compliant signal contact captured within each of said at least one signal aperture, said signal contact having a signal block contact point extending from said signal block opening and a signal device contact point extending from said signal device opening.
0. 2. The cable termination of
(a) said plate including a plurality of ground through apertures spaced from and surrounding said at least one signal aperture, each of said ground apertures extending between said face surface and said device surface, said ground apertures each having a ground block opening in said face surface and a ground device opening in said device face; and
(b) an electrically-conductive compliant ground contact captured within each of said ground apertures, said ground contact having a ground block contact point extending from said ground block opening and a ground device contact point extending from said ground device opening.
0. 3. The cable termination of
0. 4. The cable termination of
(a) said plate including a plurality of ground through apertures spaced from and surrounding said at least one signal aperture, each of said ground apertures extending between said face surface and said device surface, said ground apertures each having a ground block opening in said face surface and a ground device opening in said device face; and
(b) an electrically-conductive compliant ground contact captured within each of said ground apertures, said ground contact having a ground block contact point extending from said ground block opening and a ground device contact point extending from said ground device opening.
0. 5. A controlled-impedance cable termination assembly comprising:
(a) at least one controlled-impedance cable having at least one center conductor, a dielectric surrounding said center conductor, and a ground shield surrounding said dielectric;
(b) a ground block composed of an electrically conductive material, said block having a face, at least one cable through hole receiving said cable, and a means for securing said cable in said cable hole such that said cable shield is electrically connected to said ground block, said cable hole having an opening in said face, said face being polished such that said least one center conductor is flush with said face;
(c) a plate attached to said face, said plate having a face surface abutting said face and a device surface, said plate including at least one signal through aperture extending between said face surface and said device surface, said signal aperture having a signal block opening adjacent to and aligned with said cable center conductor, said signal aperture having a signal device opening in said device face; and
(d) an electrically-conductive compliant signal contact captured within each of said at least one signal aperture, said signal contact having a signal block contact point extending from said signal block opening into electrical contact with said center conductor and a signal device contact point extending from said signal device opening.
0. 6. The cable termination of
0. 7. The cable termination of
(a) said plate including a plurality of ground through apertures spaced from and surrounding said at least one signal aperture, each of said ground apertures extending between said face surface and said device surface, said ground apertures each having a ground block opening in said face surface and a ground device opening in said device face; and
(b) an electrically-conductive compliant ground contact captured within each of said ground apertures, said ground contact having a ground block contact point extending from said ground block opening into electrical contact with said ground block or shield and a ground device contact point extending from said ground device opening.
0. 8. The cable termination of
(a) said plate including a plurality of ground through apertures spaced from and surrounding said at least one signal aperture, each of said ground apertures extending between said face surface and said device surface, said ground apertures each having a ground block opening in said face surface and a ground device opening in said device face; and
(b) an electrically-conductive compliant ground contact captured within each of said ground apertures, said ground contact having a ground block contact point extending from said ground block opening into electrical contact with said ground block or shield and a ground device contact point extending from said ground device opening.
0. 9. A fixture for terminating a plurality of controlled-impedance cables with a ground block, each of said cables having a center conductor, a dielectric surrounding said center conductor, a ground shield surrounding said dielectric, said cable having a free end and connector at another end, said ground block having mounting holes, a face, and a cable through hole in said face to receive each of said cables, said fixture comprising:
(a) a generally rectangular, vertical frame having a bottom cross piece and an opposed top cross piece;
(b) four legs extending from bottom corners of said frame at an angle of at least 10° to horizontal;
(c) a block jig on said upper cross piece adapted to secure said block with said block face up;
(d) a tensioning plate having a threaded hole at each end and through holes adapted to be aligned with said cable holes in said block;
(e) a jack screw threaded into each threaded hole in said tensioning plate, said jack screw resting on said upper cross piece; and
(f) a connector jig on the bottom cross piece of said frame, said connector jig having a securement adapted for each cable connector, said securements being arranged in a arc such that the distance from said securement to the corresponding cable hole in said ground block is the same for all cables;
(g) whereby said ground block is mounted to said block jig, said tensioning plate is placed over said ground block, said cable free ends are threaded through said ground block cable holes and through the corresponding tensioning plate through holes, a coil spring is placed over each cable, a collar is secured to each cable adjacent to said spring, said cable connectors are placed in the corresponding securements, the jack screws are turned to tension the cables, the cable shields are soldered to the ground block, the jack screws are turned to remove tension from said cables, and said ground block and cable connectors are removed from said fixture.
0. 11. The controlled-impedance cable termination adapter of claim 10 further comprising:
(a) a plurality of ground through apertures in the plate spaced from and surrounding the at least one signal through aperture, each of the plurality of ground through apertures extending between the face surface and the device surface, the plurality of ground through apertures each having a ground block opening in the face surface and a ground device opening in the device surface; and
(b) an electrically-conductive compliant skewed coil ground contact captured within each of the plurality of ground through apertures, the ground contact having a ground block contact point extending from the ground block opening and a ground device contact point extending from the ground device opening.
0. 12. The controlled-impedance cable termination adapter of claim 10 wherein the plate is comprised of two sheets.
0. 13. The controlled-impedance cable termination adapter of claim 12 wherein the two sheets are mirror images, each including half of the signal through hole.
0. 14. The controlled-impedance cable termination adapter of claim 12 wherein one sheet has a majority of the signal through hole.
0. 15. The controlled-impedance cable termination adapter of claim 10 wherein the insulating plug is comprised of two parts.
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This application is a Divisional Reissue Application of Reissue application Ser. No. 15/248,185 filed on Aug. 26, 2016, both of which are Reissue Applications of U.S. Pat. No. 8,926,342 issued on Jan. 6, 2015 from application Ser. No. 14/238,215 with an effective filing date of Oct. 24, 2012. The entirety of the above-mentioned patent applications are hereby incorporated by reference herein and made a part of this application.
The present invention relates to electrical cable terminations, more particularly, to controlled impedance cable terminations which are generally used to transmit high-frequency signals in electronic equipment.
The purpose of a cable termination is to provide an interconnect from the cable to the electrical device and to provide a separable electrical interconnection between the cable and its operating environment. The characteristic of separability means that the cables are not interconnected by permanent mechanical means, such as soldering or bonding, but by temporary mechanical means.
Currently cables are terminated using a conventional type connector which is also controlled-impedance, such as an SMA (SubMiniature Version A) connector, or the cables are soldered to a printed circuit board (PCB) which is then separably connected to the working environment. The SMA connectors, while being generally the same impedance environment as the cable, have impedance mismatches which cause high-frequency attenuation at the point of interface between the cable and the connector and the connector and its working environment, such as like a PCB. Additionally, these cable terminations often require through holes in PCB's for mounting and, consequently, it can be difficult to design the best possible controlled impedance environment. These types of cable terminations are generally for a single cable and require a substantial amount of PCB area to terminate, thus decreasing the density capability of connections.
Another form of prior art is a system which uses two independent parts to mate several cables to its electrical environment. This system uses one part that is generally soldered to a printed circuit board and another part that is generally mated to several cables. The two pieces can be plugged together to form the controlled impedance interconnection. These systems are better-controlled impedance environments but are limited in the densities at which the cables can be used. That is, the cables require a minimum space between them to achieve the controlled impedance environment and thus only a small number of cables can be terminated in a given area.
Another form of prior art, disclosed in U.S. Pat. No. 7,544,093, is a system which employs removable cables that are held to the device by means of a spring. The cable has a terminal end which makes the signal conductor protrude from the cable terminal end. The terminal is then pressed to the device by means of a spring and the ground shield of the cable is connected to the device by a conductive rubber ground shield that shorts the terminal ground to the device ground.
The present invention is an apparatus and method for terminating a controlled-impedance cable that uses a compliant contact element at the point of termination minimizes detrimental electrical effects of the termination.
The present invention includes a cable terminator that employs compliant electrical contacts to provide an interface between the controlled-impedance cable (hereinafter, simply “cable”) and another device. The assembly is removably attached to the electrical device by a compression force in a direction of compression typically provided by jack screws that may not compress the assembly and device together linearly. Compliant contacts compensate for noncoplanarities between the conduction points of the electrical device.
Each embodiment of the terminator includes a conductive ground block for securing the cable by its ground shield and providing a common ground, one or more compliant signal contacts for making the electrical connection between the cable center conductor(s) and the electrical device, optional compliant ground contacts for making the electrical connection between the ground block and the ground plane of the device, and a plate mounted to the ground block that holds the contacts.
The ground shield of all of the cables are electrically connected to the ground block. The present invention contemplates several different methods to accomplish this including soldering the cable ground shield, crimping the ground shield, potting with a conductive adhesive, insert molding, press fitting a rigidized ground shield, threading, and twist-lock. Once the cables are anchored in the ground block, the ground block face and cable ends are dressed to make a reliable electrical contact with compliant contacts. Dressing may include polishing by some mechanical means, such as by milling, grinding, or sanding, in order to make sure that the cable center conductor is positioned at a known depth with respect to the ground block face.
Example compliant contacts for use with the present invention include spring probes, electrically-conductive rubber contacts, fuzz button contacts, stamped metal contacts, chemically etched contacts, and skewed coil contacts.
The plate holds the contacts. Features of the plate include a face surface that abuts the ground block face, a device surface that generally abuts the device, and at least one through aperture for the contacts. Each aperture has a ground block face opening and a device face opening. The apertures for the signal contacts are aligned with the corresponding cable hole in the ground block.
The cable center conductor is connected to the signal conduction point of the electrical device by the compliant signal contact. In most configurations, the signal contacts are surrounded by a number of ground contacts that connect either the ground block or the cable shield to the device in a pattern that closely mimics the impedance environment of the cable. The impedance of the system can be changed by changing the position of the ground contacts with respect to the signal contact or by changing the insulating material.
The skewed coil contact is captured in a through aperture in the plate. The aperture has a larger center section that narrows to a smaller block opening at the side adjacent to the ground block and to a smaller device opening at the other end. The length of the contact leads is such that the leads extend from the openings. Alternatively, the block opening is as wide as the center section. Optionally, the contact area between the center conductor and device and the corresponding contact lead can be increased by a pair of conductive bosses that the contact is captured in that is as wide as the cable center conductor. Optionally, the remaining space of the aperture is filled with a compliant, electrically conductive elastomer that adds resiliency and aids in electrically shorting the coil loops.
The fuzz button contact is cylindrical and forced into an aperture that is narrower at the center than the ends. The contact ends extend from the plate.
The conductive rubber contact for the signal contact can be cylindrical with a centrally-located annular depression that fits on an annular protrusion in the aperture. The contact ends extend from the plate. The conductive rubber contact for the ground contact can be the same structure as the signal contact or can be circular, surrounding the signal contact.
The etched or stamped contact is a strip of conductive material in a C shape that is captured in a C-shaped aperture.
The electrical connection between the center conductor and the signal contact and the electrical connection between the ground block and the ground contacts are compression connections. With the contacts installed in the plate, the plate is mounted to the ground block with mechanical attachments, thereby forcing the end of the signal contact against the end of the center conductor and the ends of the ground contacts against the ground block. Alternatively, the electrical connection between the center conductor and the signal contact is a solder connection. Alternatively, the end of the center conductor is formed into a compliant spring like the skewed coil contact.
The plate can be either insulating or conductive. The insulating plate is made of a non-electrically-conductive material. A conductive plate is preferably composed of an electrically-conductive metal that couples the ground contacts, thereby providing more precise impedance matching to the signal contact. The signal contact is insulated from the conductive plate by an insulating centering plug or a non-conductive coating.
Alternatively, the signal contact aperture is within a conductive boss. The boss is surrounded by an insulating annulus that insulates the boss from the conductive plate.
Also disclosed is a method and apparatus for assembling cables to the ground block so that the cables are the same length to within a very small tolerance. To facilitate the method, a soldering fixture is used that has a frame, a connector jig, a block jig, and legs. The frame is generally rectangular and stands vertically. The connector jig is mounted to the lower cross piece of the frame. The block jig is mounted to the upper cross piece of the frame. Four legs extend from the bottom corners of the frame in generally opposite directions at an angle of at least 10° from horizontal so that they prevent the frame from falling over but allow the user to tilt the frame.
The connector jig locks the cable connectors at a fixed distance away from where the other end of the cable will be soldered to the ground block. The connector jig locks the connectors in an upwardly open arc so that the cables are the same length to the ground block.
The ground block is secured to the block jig, face up, which is secured to the upper cross piece. A tensioning plate is mounted to the upper cross piece. Jack screws are threaded into holes at the end of the tensioning plate.
The cable sheath is stripped and the stripped portion is fed through the hole in the ground block and a corresponding cable hole in the tensioning plate. A coil spring is placed on each cable and a collar is tightly secured to the cable.
After putting the connectors in the connector jig, the jack screws are tightened until there is adequate tension on the cables. Each cable shield is soldered to the ground block. The angled legs allow the user to tilt the fixture for easier access to each side of the ground block. After the solder and ground block have cooled sufficiently, the jack screws are loosened, and the collars, springs, and tensioning plate are removed. The ground block is removed from the frame and the connectors are removed from the connector jig.
The ground block face is finished smooth and evenly flat by sanding, milling, planing, skiving, broaching, or any other appropriate method.
Objects of the present invention will become apparent in light of the following drawings and detailed description of the invention.
For a fuller understanding of the nature and object of the present invention, reference is made to the accompanying drawings, wherein:
The present application hereby incorporates by reference U.S. Provisional Patent Application No. 61/550,543 in its entirety, on which portions of this application are based.
The present invention is an apparatus and method for terminating a controlled-impedance cable that minimizes detrimental electrical effects of the termination by using a compliant or compressible contact element at the point of termination. With the present invention, impedance mismatches are minimized, allowing the cable to be more useful in high-frequency signal ranges. The present invention can be used with any cable structure where the impedance between the inner conductor(s) and the ground shield is controlled.
In addition, the present invention increases the density at which the controlled-impedance cables can be used. That is, with the present invention, more cables can be terminated in a given amount of space than with terminations of the prior art. Further, the interface between the components of the present invention may not require through-hole mounting, which may further enhance density capability.
The present invention calls for proper dressing of the cable end so that small, compliant contacts can be used for separably interconnecting the controlled-impedance cables to whatever electrical device the user desires. A prime example is connecting two printed circuit boards which must communicate with each other at high frequency, such as connecting a computer central processing PCB with its random access memory PCB or another central processing PCB.
As shown in
The present invention is for use with controlled-impedance cables having one or more center conductors. A coaxial cable 30 has a center conductor 32 surrounded by a dielectric 34 with a ground reference shield 36 outside the dielectric 34. Optionally, a sheath 38 covers the shield 36. A twin-axial cable 30 has two center conductors 32 surrounded by a dielectric 34 with a ground reference shield 36 outside the dielectric 34 and a sheath 38 covering the shield 36. Cables with more than two center conductors are available. Although not specifically described, the present invention can be adapted to accommodate cables having more than two center conductors.
The terminator 10 of the present invention has several embodiments. Each embodiment includes a conductive ground block 16 for securing the cable 30 by its ground shield 36 and providing a common ground, one or more compliant signal contacts 12 for making the electrical connection between the cable center conductor(s) 32 and the electrical device 2, optional compliant ground contacts 14 for making the electrical connection between the ground block 16 and the ground plane of the device 2, and a plate 18 mounted to the ground block 16 that holds the contacts 12, 14.
In order to produce the assembly 8, the ground shield 36 of all of the cables 30 are electrically connected to the ground block 16. The present invention contemplates several different methods to accomplish this. The ground shield 36 may be soldered into a hole 40 in ground block 16. The cable sheath 38 is stripped back at least the length of the ground block hole 40. The cable 30 is inserted into the hole 40 up to the end of the sheath 38 and the shield 36 is soldered to the ground block 16.
Alternatively, the cable 30 may be crimped into the ground block hole 40. After the sheath 38 is stripped back, the cable 30 is inserted into the hole 40. The hole 40 may have the path through which the cable 30 runs geometrically altered after insertion of the cable 30 to a point where the size of the path is smaller than the size of the cable 30, thereby anchoring the cable 30 to the ground block 16 and electrically connecting the shield 36 to the ground block 16.
Other methods of anchoring the cable 30 to the ground block 16 include potting the ground shield 36 with a conductive adhesive once it is placed in the hole 40, insert molding the ground block 16 with the cable 30 in place at the time of molding, and press fitting a rigidized, for example, pretinned, ground shield into the hole 40.
Once the cables 30 are anchored in the ground block 16, the face 20 of the ground block 16 and cable ends 136 are properly dressed to make a reliable electrical contact with small compliant contacts. The cable ends 136 and the ground block face 20 may need to be polished and planarized by some mechanical means, such as by milling, grinding, or sanding, in order to make sure that the cable center conductor 32 is positioned at a known depth with respect to the ground block face 20, in this case flush with the ground block face 20. The cable ends 136 and face 20 may also require noble metal plating to prevent the polished surface from oxidizing or otherwise degrading so as to inhibit acceptable electrical connection to the center conductor 32 and the ground block 16.
Methods of removably connecting the cable 30 to the ground block 16 are shown in
In the configuration of
The second method of removably attaching the cable 30 to the ground block 16 calls for the use of a twist-lock attachment 300, as shown in
The cable end 308 is inserted into a hole 310 in the ground block 16. Protrusions 312 from the twist-lock component 302 slide down opposed notches, not shown, in the sides of the hole 310 until they align with an annular depression 316 in the hole 310. With this alignment, the spring 304 is compressed so that it presses the center conductor 32 to the signal contact 12 in order to produce an electrical connection between the center conductor 32 and the signal contact 12. The twist-lock component 302 is turned so that the protrusions 312 are captured by the annular depression 316, thereby retaining the cable 30 in the hole 310.
In some designs, particularly with the removable attachments, the cable center conductor 32 may not be exactly flush with the ground block face 20, that is, it may be slightly recessed into or protruding from the ground block face 20. That recession or protrusion can be as much as 0.05 inch. The present specification and claims use the term, “flush”, to indicate that the center conductor 32 is actually flush with, slightly recessed into, or slightly protruding from the ground block face 20 by as much as 0.05 inch.
In most of the present figures, the ground block 16 is generally a rectangular solid where the cables 30 are perpendicular to the ground block face 20. However, the ground block 16 can have other shapes.
Example compliant contacts for use with the present invention include spring probes, electrically-conductive rubber contacts, fuzz button contacts, stamped metal contacts, chemically etched contacts, and skewed coil contacts.
A typical spring probe consists of a hollow barrel with a spring and one or two plungers. The spring is housed in the barrel with the end of the plungers crimped in opposed open ends of the barrel at the ends of the spring. The spring biases the plungers outwardly, thereby providing a spring force to the tip of the plungers.
Conductive elastomer bumps are made of rubber and/or silicones of varying types with embedded conductive metal elements. The elastomer bump can work when the device conduction point is elevated off the device, thus sometimes requiring a protruding feature from the device or the addition of a third conductive element to the system to act as a protruding member.
Alternatively, the contact can be made of a single sheet of anisotropic conductive elastomer which is an elastomeric sheet that only conducts electricity through its thickness.
A fuzz button is a wire that is crumpled into a cylindrical shape. The resulting shape looks very much like tiny cylinder made of steel wool. When the cylinder is placed within a hole in a sheet of nonconductive material, it acts like a spring that is continuously electrically shorted. Like elastomer bumps, the fuzz button can be used with a third element needed to reach inside the hole of the nonconductive sheet to make contact with the fuzz button.
Skewed coil contacts of various types and configurations are described in U.S. Pat. Nos. 7,126,062 and Re41,663, both of which are incorporated herein by reference. Briefly, the skewed coil contact includes a coil of conductive, inherently elastic wire with a pair of oppositely extending leads. The leads extend in a direction angled from the coil axis. During compression, the coil loops are electrically shorted together while they slide along each other.
The figures illustrate the use of skewed coil contacts, fuzz button contacts, conductive rubber contacts, and stamped metal or a chemically etched contacts. As indicated above, the plate 18 holds the contacts 12, 14. The structure of the plate 18 depends on the type of contact. Regardless of the type of contact, the plate 18 has several common features. These features are shown in
When there are two or more cables 30, there may be ground contacts 14 that are “shared” between cables 30. For example, in the coaxial structure of
As shown in
An alternative configuration is shown in
Because of the very small size of the wire used to make the skewed coil contact 42, the contact area between the skewed coil signal contact 12 and the cable center conductor 32 is small. This can cause a capacitive reactance at the interface of the contact leg 56 and the cable center conductor 32 which can cause reflections at high frequencies. To help alleviate this problem, the through aperture 44 is wide for its entire length, as in
In
Optionally, in any skewed coil contact configuration, after the contact 42 is installed, the remaining space of the aperture 44 is filled with a compliant, electrically conductive elastomer that adds resiliency and aids in electrically shorting the coil loops.
As shown in
As shown in
The conductive rubber contact for the ground contact 14 can be of the same structure as the signal contact 12.
Alternatively, the conductive rubber contact 112 for the ground contact 14 is circular, surrounding the signal contact 12, as in
In
An alternate terminator assembly 10 using the ground block of
The electrical connection 80 between the center conductor 32 and the signal contact 12 and the electrical connection 82 between the ground block 16 and the ground contacts 14 are compression connections. With the contacts 12, 14 installed in the plate 18, the plate 18 is mounted to the ground block 16 with mechanical attachments 28, such as screws, rivets, and the like. Installing the plate 18 forces the end of the signal contact 12 against the end of the center conductor 32 and forces the ends of the ground contacts 14 against the ground block 16.
Alternatively, the electrical connection 80 between the center conductor 32 and the signal contact 12 is a solder connection while the electrical connection 82 between the ground block 16 and the ground contacts 14 is a compression connection.
Alternatively, as shown in
The plate 18 can be either insulating or conductive.
A conductive plate 88, shown in
The plug 90 may be press fit into a through hole 92 in the conductive plate 88 or it may be bonded into the hole 92 with an adhesive. Alternatively, as shown in
Alternatively, the signal contact 12 can be insulated from the conductive plate 88 by a non-conductive coating such as powder coating. In this case the signal contact aperture may be made larger such that the coating reduces the aperture size to the appropriate size for use. As with the plug 90, the impedance of the system can be changed by either changing the thickness of the coating or by changing the coating material, thereby changing the dielectric constant of the material.
The center conductors 32 of the cable 30 are connected to the signal conduction points 4 of the electrical device 2 by the compliant signal contacts 12. As shown in
As with the coaxial cable configurations, the plate 18 can be either insulating or conductive.
The present specification describes a number of different compliant contacts that can be used in the present invention. These are merely examples. The present invention contemplates that any form of compliant contact that has the appropriate characteristics for the particular application can be used. In addition, the present specification contemplates that different types of contacts can be use in the same assembly. For example, a skewed coil contact can be used as the signal contact and a circular conductive rubber contact can be used as the ground contact.
The present invention produces a controlled-impedance, compliant cable to device interface which can be less than 1 mm thick (the length of the compliant contacts 12, 14) and mimics the controlled-impedance environment of the cable 30, thereby ensuring the highest possible signal rates through the termination.
The present invention can also produce a controlled-impedance device to device interface because the cables 30 can have terminators 10 at both ends.
When working with very high frequencies, for example, frequencies in the Gigahertz range and above, cable lengths are very critical. In order to maintain phase synchronization between signals on different cables, the cables must have as close to the exact same length as is practical. The present specification describes a method and apparatus for assembling cables 202 to the ground block 200 so that the cables 202 are the same length to within a very small tolerance, on the order of 0.001 inch for cables 202 that are 6 inches long from the cable connector 204 to the block face 206. The present method can be used for cables of any length. Longer cables result in larger tolerances. At a given temperature, a cable length can be controlled to within 0.03% to 0.05% of the cable's overall length.
To facilitate the method, a soldering fixture 210 is used. The fixture includes a frame 212, a connector jig 214, a block jig 216, and legs 218.
The frame 212 is generally rectangular and stands vertically. The connector jig 214 is mounted to the lower cross piece 222 of the frame 212 inside the frame 212. The block jig 216 is mounted to the upper cross piece 224 of the frame 212 outside of the frame 212. Four legs 218 extend from the bottom corners of the frame 212 in generally opposite directions. The legs 218 are angled from the frame 212 by at least 10° from horizontal so that they prevent the frame 212 from falling over but allow the user to tilt the frame 212. The preferred angle is about 20° so that the frame can be tilted between 70°, 90°, and 110° from vertical to facilitate use, as described below. The present invention contemplates that the angle of the legs 218 can vary from application to application.
The fixture 210 locks the connector 204 of each cable 202 at a fixed distance away from where the other end of the cable 202 will be soldered to the ground block 200. The connector jig 214 locks the connectors 204 and can be designed appropriately for any particular type of connector 204.
Because the distance (pitch) between cables 202 at the ground block 200 is smaller than the diameter of the connectors 204, the cables 202 cannot be secured parallel to each other to achieve equal length. To solve this problem, the connector jig 214 locks the connectors 204 in an upwardly open arc 240 so that the cables 202 are the same length to the ground block 200.
As shown in
A tensioning plate 252 is mounted to the upper cross piece 224. There are threaded holes 254 at each end of the tensioning plate 252 into which the jack screws 256 are threaded. The tensioning plate 252 is placed over the ground block face 206 and the jack screws 256 are turned into the holes 254 so that the tensioning plate 252 rests on the ground block face 206. The tensioning plate 252 has a cable hole 258 for each cable 202 that is aligned with the ground block cable hole 248 for the same cable 202. Optionally, the tensioning plate 252 is machined out above the ground block 200, as at 270, to facilitate access to the face 206.
Each cable 202 is trimmed so that it is at least 1.4 inches longer that the assembled length of the cable 202. The cable 202 is stripped at the end so that the length from the connector 204 to the stripped portion remains constant. The non-stripped portion of the cable 202 extends into the ground block hole 248 approximately 0.06 inches.
As shown in
As shown in
The connectors 204 are placed into the corresponding securement 228 and the two jack screws 256 are tightened until the cables 202 have enough tension to be pulled against their securements 226, making sure that the cables 202 are straight between the connector 204 and the ground block 200 with no kinks or bends. Optional stops 266 prevent the jack screws 256 from being tightened too much. In the illustrated configuration, the stops 266 are spacers 292 on the jack screws 256 between the tensioning plate 252 and the jack screw heads 294, as shown in
The springs 260 independently keep each cable 202 tight so that the distance from the connector 204 ground block face 206 remains consistent for all of the cables 202.
Each cable shield 208 is soldered to the ground block 200 such that the solder flows into the hole 248. The angled legs 218 allowing the user to tilt the fixture 210 permit easier access to each side of the ground block 200 for soldering.
After the solder and ground block 200 have cooled sufficiently, the jack screws 256 are loosened until tension on the springs 260 is released. The collars 262, springs 260, and tensioning plate 252 are removed. The ground block 200 is removed from the frame 212 and the connectors 204 are removed from the connector jig 214. The excess cable is cut off.
Next, the ground block face 206 is finished smooth and evenly flat. There are a number of ways known in the art to accomplish this, including sanding, milling, planing, skiving, and broaching. Once the cables 202 are secured in the ground block 200, any conceivable method can be used to dress the face 206 of the ground block 200 which achieves the desired surface finish and/or planarity.
Thus it has been shown and described a controlled-impedance cable termination and a method and apparatus for attaching controlled-impedance cables to the termination. Since certain changes may be made in the present disclosure without departing from the scope of the present invention, it is intended that all matter described in the foregoing specification and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
Diaz, Sergio, Vinther, Gordon A, Hebert, Jeffrey G
Patent | Priority | Assignee | Title |
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Oct 24 2012 | VINTHER, GORDON A | ARDENT CONCEPTS, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 045252 | /0171 | |
Oct 24 2012 | DIAZ, SERGIO | ARDENT CONCEPTS, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 045252 | /0171 | |
Oct 24 2012 | HEBERT, JEFFREY G | ARDENT CONCEPTS, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 045252 | /0171 | |
Mar 16 2018 | Ardent Concepts, Inc. | (assignment on the face of the patent) | / |
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