High Speed Bypass Cable Assembly

Abstract

A cable bypass assembly is disclosed for use in providing a high speed transmission line for connecting a board mounted connector of an electronic device to a chip on the device board. The bypass cable assembly has a structure that permits it, where it is terminated to the board mounted connector and the chip member, or closely proximate thereto, to allow signals to be transmitted at greater than 10 GHz with substantially lower loss than a traditional FR4 circuit board.

Claims

1. A cable bypass assembly, comprising: a cage that defines a port; a first connector positioned in the cage and including a first body with a card-slot, the first body supporting a plurality of terminals, each terminal of the plurality of terminals including a contact portion positioned in the card slot and a tail, wherein two terminals of the plurality of terminals are adjacent each other and form a first terminal pair; a cable with a first end and a second end that defines a length, the cable including a pair of signal conductors disposed within an insulative body portion of the cable, the signal conductors extending in a spaced-apart relationship through the insulative body portion along the length, the cable further including a conductive shield extending over an exterior of the cable body portion and an insulative outer covering extending over the cable conductive shield, the first end being terminated directly to selected terminal tails of the first connector in a manner so that the pair of signal conductors are in electrical communication with a pair of signal terminal tails, and wherein the conductive shield is connected to a ground terminal adjacent the pair of signal terminals; and a second connector connected to the second end, the second connector including a second body that supports a second pair of terminals, each terminal of the second pair of terminals including a contact portion and a tail portion, the tail portion of each terminal of the second pair of terminals connected to one of the signal conductors and the second connector further including a ground terminal connected to the ground shield.

2. The cable bypass assembly of claim 1, wherein the plurality of terminals in the first connector are supported by two terminal assembly supports that align a portion of the terminals on both sides of the card slot so that in operation, during mating with an opposing mating connector the contacts portions on both sides of the card slot are deflected in opposing directions.

3. The cable bypass assembly of claim 2, wherein the cable is configured to support a signaling frequency of at least 10 GHz.

4. The cable bypass assembly of claim 1, wherein the second connector is configured to be press-fit into a circuit board adjacent a chip member.

5. A cable bypass assembly, comprising: a cage that defines a port with a front opening; a first connector positioned in the cage and including a first body with a card-slot, the first body supporting a plurality of terminals, each terminal of the plurality of terminals including a contact portion positioned in the card slot and a tail, wherein two terminals of the plurality of terminals are adjacent each other and form a first terminal pair; a cable with a first end and a second end that defines a length, the cable including a pair of signal conductors disposed within an insulative body portion of the cable, the signal conductors extending in a spaced-apart relationship through the insulative body portion along the length, the cable further including a drain wire extending along the length, the first end being terminated directly to selected terminal tails of the first connector in a manner so that the pair of signal conductors are in electrical communication with a pair of signal terminal tails; and a second connector connected to the second end, the second connector including a second body that supports a second plurality of terminals that form a second terminal pair, each terminal of the second terminals pair including a contact portion and a tail portion, the tail portion of each terminal of the second terminal pair connected to one of the signal conductors and the second connector further including a ground terminal connected to the drain wire.

6. The cable bypass assembly of claim 5, wherein the plurality of terminals in the first connector are supported by two terminal assembly supports that align a portion of the terminals on both sides of the card slot so that in operation, during mating with an opposing mating connector the contacts portions on both sides of the card slot are deflected in opposing directions.

7. The cable bypass assembly of claim 5, wherein the card slot is recessed a substantial distance from the front opening.

8. The cable bypass assembly of claim 5, wherein the cable is configured to support a signaling frequency of at least 10 GHz.

9. The cable bypass assembly of claim 5, wherein the second connector is configured to be press-fit into a circuit board adjacent a chip member.

10. The cable bypass assembly of claim 5, wherein the second connector is configured to be connected directly to a chip member.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0010] The organization and manner of the structure and operation of the Present Disclosure, together with further objects and advantages thereof, may best be understood by reference to the following Detailed Description, taken in connection with the accompanying Figures, wherein like reference numerals identify like elements, and in which:

[0011] FIG. 1 illustrates a perspective view of one embodiment of a high speed interconnect cable assembly, developed in accordance with the Present Disclosure;

[0012] FIG. 2 illustrates a perspective view of another embodiment of a high speed interconnect cable assembly, developed in accordance with the Present Disclosure;

[0013] FIG. 3 illustrates a perspective view of another embodiment of a high speed interconnect cable assembly, developed in accordance with the Present Disclosure;

[0014] FIG. 4 illustrates a perspective and inset view of the via transfer connector of the interconnect cable assembly of FIG. 3;

[0015] FIG. 5 illustrates a perspective and inset view of the first connector member of the interconnect cable assembly of FIG. 3;

[0016] FIG. 6 is a perspective view of a second embodiment of a cable bypass assembly constructed in accordance with the Present Disclosure;

[0017] FIG. 7 is a top plan view of the cable bypass assembly of FIG. 6;

[0018] FIG. 8 is an exploded view of the assembly of FIG. 6, illustrating in greater detail the board connector to which the cable bypass assembly is terminated;

[0019] FIG. 9 is a perspective view of the board mounted connector of FIG. 8, with the first ends of the bypass assembly attached thereto;

[0020] FIG. 10 is a partially exploded view of FIG. 9;

[0021] FIG. 11 is a top plan view of FIG. 9, with the EMI shield removed for clarity;

[0022] FIG. 11A is a side elevational view of FIG. 11;

[0023] FIG. 12 is perspective view of four pairs of signal wires terminated to the board connector terminal assembly and with one set of the shielding extensions removed for clarity;

[0024] FIG. 12A is the same view as FIG. 12, but taken from the rear thereof;

[0025] FIG. 12B is a end view of two pairs of signal wires with an associated shielding extension in place, illustrating the relative alignments of the signal conductors with each other and to the shielding of the cables;

[0026] FIG. 13 is a perspective view of one manner of terminating the ends of the cables of the cable bypass assembly which is opposite that of the termination to the board mounted connector;

[0027] FIG. 13A is the same view as FIG. 13, but with one of the exterior shielding components removed for clarity;

[0028] FIG. 13B is the same view as FIG. 13A but with the lower shielding component removed and the terminal support in place on the terminals attached to the second end of the cable;

[0029] FIG. 13C is the same view as FIG. 13B but with the terminal support removed for clarity;

[0030] FIG. 13D is the same view as FIG. 13C, but taken from the other end thereof;

[0031] FIG. 13E is a sectional view of FIG. 13;

[0032] FIG. 14 is an embodiment of a termination structure for direct connection to a chip member;

[0033] FIG. 14A is an exploded view of FIG. 14;

[0034] FIG. 14B is an enlarged detail view of FIG. 14A.

[0035] FIG. 15 is a partially exploded view of an extent of flexible circuitry which may be used as a signal transmission line in cable bypass assemblies of the disclosure; and,

[0036] FIG. 16 is a graph comparing the losses between 12-inch lengths of signal transmission lines incorporated on a circuit board made from FR-4 material and a cable bypass assembly constructed in accordance with the principles of the disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] While the Present Disclosure may be susceptible to embodiment in different forms, there is shown in the Figures, and will be described herein in detail, specific embodiments, with the understanding that the disclosure is to be considered an exemplification of the principles of the Present Disclosure, and is not intended to limit the Present Disclosure to that as illustrated.

[0038] In the embodiments illustrated in the Figures, representations of directions such as up, down, left, right, front and rear, used for explaining the structure and movement of the various elements of the Present Application, are not absolute, but relative. These representations are appropriate when the elements are in the position shown in the Figures. If the description of the position of the elements changes, however, these representations are to be changed accordingly.

[0039] While the Present Disclosure may be susceptible to embodiment in different forms, there is shown in the Figures, and will be described herein in detail, specific embodiments, with the understanding that the disclosure is to be considered an exemplification of the principles of the Present Disclosure, and is not intended to limit the Present Disclosure to that as illustrated.

[0040] FIGS. 1-5 provide various perspective views of some basic components of a high speed interconnect cable assembly, developed in accordance with the teachings and tenets of the Present Disclosure.

[0041] Referring more specifically to FIG. 1, high speed interconnect cable assembly 10 generally comprises chip member 12 mounted on printed circuit board member 14, first connector member 16 interfacing between chip member 12 and bypass cable member 18, and termination member 20 interfacing between bypass cable member 18 and second connector member 22 disposed at the edge of printed circuit board member 14.

[0042] Preferably, chip member 12 may comprise a PHY Chip, or any other surface-mounted, physical layer device, known in the art, from which a high speed signal is generated, such as an ASIC and transmitted to a cable assembly. Chip member 12 is mounted to any currently-known printed circuit board, using preferably any of the various currently-known mounting means. Preferably, an FR-4 type printed circuit board is used, in an effort to take advantage of its low cost and wide usage. For purposes of the Present Disclosure, the generated high speed signal may be any type of signal, but typically a data signal, generally having a frequency of 5 GHz and above, and most preferably and is a data signal having a frequency of 10 GHz or more.

[0043] Bypass cable member 18 is connected to chip member 12 by means of first connector member 16. First connector member 16 is capable of transmitting a signal greater than 10 GHz between chip member 12 and bypass cable member 18. The interface between first connector member 16 and chip member 18 may be by any known means, including, for example, a plug-receptacle connection, a friction-based connection or the like. It is preferred that the interface be removable. First connector member 16 is preferably capable of receiving the high speed signal generated by the chip member and transmitting it to the bypass cable member without need for a repeater or an amplifier, and without having to use the conductive properties of printed circuit board 14.

[0044] Bypass cable member 18 comprises a flexible circuit member, such as a cable, extending from first connector member 16 to termination member 20. Preferably, bypass cable member 18 is capable of receiving and carrying signals above 10 GHz. Preferably, bypass cable member 18 includes one or more wire pairs that transmit differential signals at high speeds. Each such wire pair may have a ground, or drain, wire associated with it. Further, the pairs may be enclosed within bypass cable member 18 and within an associated cable shield. Like first connector member 16, bypass cable member 18 is preferably capable of receiving the high speed signal generated by first connector member 18 and transmitting it to termination member 20 without need for a repeater or an amplifier, and without having to use the conductive properties of printed circuit board 14.

[0045] Termination member 20 is electrically connected to bypass cable member 18, and receives the signal from bypass cable member 18. Like all other elements in interconnection assembly 10, termination member 20 is capable of receiving signals greater than 10 GHz. Preferably, termination member 20 is located at or near the edge of printed circuit board 14. Termination member 20 may be mounted to the edge of printed circuit board 14. Alternatively, termination member 20 may be freestanding, and not connected to any aspect of assembly 10. Termination member 20 may receive bypass cable member 18 though any methods and means as currently described in the art.

[0046] Second connector member 22 preferably provides one end of a male-female relationship with termination member 20 (with termination member 20 providing the second end). It is not imperative that second connector member 22 (or termination member 20) be specifically relegated to the male or female end, as the teachings of the Present Disclosure will nevertheless be realized.

[0047] Second connector member 22 is preferably not disposed on any other aspect of interconnection assembly 10 of the Present Disclosure, i.e., second connector member 22 is not mounted on printed circuit board 14. Second connector member 22 receives the signal from termination member 20, and transmits the signal to its next or final destination.

[0048] The discussion above focused on a single interconnection assembly. Nevertheless, a plurality of interconnection assemblies may be used on a single printed circuit board, each generally comprising the above-referenced elements. A plurality of assemblies is generally illustrated in FIG. 1. Further, in a second embodiment, which is illustrated in FIG. 2, lamination member 24 may encompass all or part of multiple bypass cable members 18 for ease in assembly, as well as to maintain order on printed circuit board 14 and reduce the cost of assembly 10. Preferably, lamination member 24 may comprise a rigid, formable polymer material that can be molded over both first connector member 16 and bypass cable member 18.

[0049] Further, in another embodiment, a plurality of interconnection assemblies, used on a single printed circuit board, may be channeled to a single termination member 26 for transmission of signals beyond the printed circuit board. As illustrated in FIG. 3, bypass cable members 18 extend from chip members 12, via first connector member 16, towards first via transfer connectors 28. Each via transfer connector 28 allows the signal being carried in bypass cable members 18 to pass through holes (or vias) in the printed circuit board where they connect with termination member 26.

[0050] FIG. 4 illustrates a perspective close up of the connection of via transfer connectors 28 to termination member (not shown in FIG. 4). As illustrated, each via transfer connector 28 houses the termination of bypass cable members 18. Individual wires 30 extending from bypass cable members 18 are mounted within connector housing 32. Connector housing 32, along with individual wires 30 and a portion of bypass cable members 18, are overmolded with terminal housing 34. Terminal housing 34 is then inserted into the via hole of the printed circuit board, where it couples to termination member.

[0051] FIG. 5 illustrates a perspective close up of first connector member 16. As illustrated, each first connector 16 houses the termination of bypass cable members 18. Individual wires 36 extending from bypass cable members are overmolded with terminal housing 38. Terminal housing 38 is then coupled to chip member 12.

[0052] FIGS. 6-13E illustrate another embodiment of a bypass cable assembly 100 constructed in accordance with the principles of the Present Disclosure. As shown in FIG. 6, a circuit board 101 that is used in an electronic device (not shown) has mounted thereon a chip member 104, such as an ASIC, at one location and a shielding cage 102 mounted to the circuit board at another location, remote from the one location. The shielding cage 102 houses a receptacle connector assembly 110 that includes a receptacle connector 112 configured to receive the mating blade (typically the leading edge of a circuit card) of an opposing, mating connector (not shown) in a elongated card-receiving slot 113. The connector 112 may also include a channel 114 disposed underneath the card slot 113 to receive a polarizing member of the mating connector. The connector 112 is accessible through an opening 103 at one end of the shielding cage 102. A portion of the shielding cage 102 extends past the edge of the circuit board 101 and out of the enclosure which houses the circuit board 101. This opening 103 permits access to the connector 112 from the exterior of the device and permits the insertion of a mating connector, typically in the form of a plug connector, therein in order to connect the device to another device and permit the transfer of signals between them.

[0053] A bypass cable assembly 105 is provided to connect together, the connector 112 and the chip member 104, in order to form a signal transmission line extending therebetween for transmitting signals at high speeds of approximately 5 GHz and greater and preferably of approximately 10 GHz and greater. The cable assembly 105 includes a preselected length of cable 107 that has at a first end 107a thereof, a first termination assembly and at a second and opposite end 107b thereof, a second termination assembly. As shown best in FIG. 12B, each cable 107 may be of the twin-ax type, in which a pair of signal conductors 144A, 144B are positioned in spaced-apart relationship within an insulative body 142. This cable body 142 is surrounded by an outer conductive shielding layer 148 that is located underneath an exterior, insulative covering 140 and all of the cable elements may be formed as the single component illustrated. The structure of this particular type of twin-ax cable lends itself to uniformity throughout its length so that a consistent impedance profile is attained for the length of the cable. The cable assemblies 105 of this disclosure may include as few as one or two cables, or they may include greater numbers, such as the eight cables shown in FIGS. 6, 9 & 11.

[0054] In order to avoid losses that normally occur in the use of signal transmission lines in the circuit board 101 using FR-4 as the board material, the cables 107 are used as the signal transmission lines. As noted above, the cables 107 are made in a manner that controls their size, thickness and the position and spacing of the signal conductors 144A, 144B so as to define a constant impedance profile throughout the lengths of the cables. Accordingly, twin-ax type of cable is desirable as well as flexible circuitry where positioning of the conductors and insulators may be controlled to a high degree of tolerance. Problems with impedance profiles typically occur at the termination points of cables where the geometry of the cable disrupted in order to effect a termination. One such solution to this problem is disclosed in U.S. Pat. No. 6,454,605, issued Sep. 24, 2002 and assigned to the assignee of the Present Disclosure and which is hereby incorporated by reference, in its entirety.

[0055] The cable assemblies of the Present Disclosure are terminated at their opposite ends 107A, 107B in a manner that seeks to reduce the modification of the cable geometry in order to reduce the magnitude of the aforementioned discontinuities and to prevent to the extent possible excessive loss, noise and crosstalk. Returning to the drawings and in particular FIGS. 12 & 12A, it can be seen that the terminals 120 of the receptacle connector 112 have tail portions 132 that extend outwardly from the rear face of the terminal assembly supports 118A, 118B and contact portions 130 that extend forwardly within the card-receiving slot 113 of the body of the receptacle connector 112. The terminal contact and tail portions 130, 132a, 132b, extend in a continuous, generally horizontal extent through the connector without any vertical terminal extents that would provide an interruption of the horizontal extent. Consequently, as used herein, the term uninterrupted means a generally horizontal extent without any vertical portions. Similarly, generally horizontal extent also means that there are no vertical portions of the terminals that change the levels of the terminal contact and tail portions as would be found in terminals configured for surface mounting such as the low speed, power and status terminals 134 that are interposed between the high speed terminal sets. These non-high speed terminals 134 may be positioned with the use of a tail aligner block 116 or the like. In order to provide strain relief and to facilitate assembly, two cables may be held together by a block 106 applied to the cables 107 downstream of the termination areas.

[0056] In this manner, a direct connection is effected between the cable first end 107A and the connector 112, in a manner such that the signal terminal tail portions 132a, 132b are aligned with the exposed leads of the cable conductors 144A, 144B so that the exposed leads may be placed on the flat surfaces which the terminal tail portions 132a, 132b preferably provide. The inner shielding 148 of each cable 107 is pulled back over the exposed end of the cable and a shield extension 146 is provided for engaging these cable ends. The extension 146 is shown as a dual extension that can accommodate two cables. The shield extension 146 has what may be considered a cup portion 145 that is formed in a configuration that is generally complementary to the exterior configuration of the cable 107, and it is provided with contact feet 146a-c for contacting the associated terminal tail portions 132c of ground terminals in the receptacle connector 112.

[0057] The dual shield extension 146 shown in the drawings has two such cup portions 145 and three contact feet. Two contact feet 146a, 146b are formed along the outer edges of the cup portion 145, while the third contact foot 14c is formed between the cup portions 145. The contact surfaces 147 formed on the bottom of the contact feet are preferably aligned with each other along a common plane, shown as H in FIG. 12B. The conductors 144A, 144B of the cable 107 are also preferably aligned with the contact feet, along H as illustrated best in FIG. 12B. In this manner a direct connection is effected between first ends 107A of the cables 107 and the board mounted connector 112, thereby eliminating the need for surface mounting or through hole mounting of the connector high speed terminal tails, all of which contribute to loss, noise and crosstalk at high speeds. Terminals of the connector 112 for which high speed performance is not an issue, such as low speed signal terminals and/or power and status terminals 134, may be terminated in conventional manners mentioned above and they are shown in FIGS. 12 & 12A as surface mounted, and such terminals may be disposed between sets of high speed terminals as illustrated for additional separation between the high speed terminal sets. Removing the high speed signals of the receptacle connector from attachment directly to the board, reduces the cost in formation and manufacture of the circuit board 102. Additionally, the termination style shown in the drawings mirrors the geometry of the cable and provides generally complete shielding at the direct connection.

[0058] The shield extensions 146 provide as close as can be attained complete shielding at the direct termination to the board connector and they extend forwardly to completely cover the exposed ends of the cable signal conductors 144A, 144B as shown in FIG. 11. The shield extension mounting feet 146a-c thereof are spaced apart and contact opposing tail portions of ground terminals of the first connector 112. The shield extension feet 146a-c and the conductors 144A, 144B of the cables 107 can be soldered or welded in their attachment to the connector terminals and the shield extensions 146 may be attached to the cables 107 by contact, a conductive adhesive, soldering or other suitable means. In this manner, the cable geometry is closely replicated in the termination area and more effective shielding is provided than just an ordinary ground wire to ground terminal connection. An EMI housing 109 may be utilized to provide an enclosure, in combination with the shielding cage 102 about the cable termination area.

[0059] FIGS. 13A-D illustrate one form of termination that may be applied to the second ends of the cables 107, which may be either connected directly to the chip member or to the circuit board 101 in close proximity thereto. As illustrated in FIGS. 13B-D, the exposed leads of the cable conductors 144A, 144B are attached to signal terminals 160, shown as a pair of signal terminals 160A, 160B. These terminal preferably have flat tail portions 163 and through hole contact portions 162. The flat tail portions 163 preferably provide a flat surface to which the exposed conductors 144A, 144B may be contacted and attached via solder, welding or the like. The signal terminal 160 may be held in by an insulative support 156 that as shown is molded over body portions of the terminal 160, leaving the tail and contact portions 163, 162 exposed for termination purposes. A shield collar 152 is provided that houses the signal terminal support 156 and substantially encloses the signal terminals with a conductive shield. The shield collar 152 has a shield extension 153B that is similar in configuration to cable first end shield extensions 146 in that is has a cup portion 145 that contacts and receives the cable 107 and its inner shielding 148 therein. A cap member 153 is also provided and the cap member includes a block portion 154 that preferably abuts the terminal support 156 and which further preferably engages the shield collar 152 by way of tabs 156 that engage like holes 157 in the walls of the collar 152.

[0060] FIGS. 14-14B illustrate another embodiment of a manner or termination to a second connector. In this embodiment, the second connector 200 is one that is used to attach directly to the chip member 104, and typically to a top surface thereof. In this regard, the second connector 200 has a housing 202 that receives a plurality of cables 204, and the type of cables illustrated are of a different twin-ax structure, namely one in which each cable 204 contain a pair of signal wires 205 and a drain (ground) wire 206. The signal wires 205 have signal conductors 207 running their length and surrounded by an outer insulative covering 208 and an outer covering 209 is provided that encloses a pair of the signal wires 205 and an associated drain wire 206. A perforated base portion 210 of the housing 202 has a plurality of slots, or cavities 211, each of which is configured to receive a single terminal 212 therein. LGA-style terminals are illustrated and each such terminal 212 includes a body portion 213 that engages the housing cavity 211, a tail portion or mounting stub 214 that extends out of the cavity 211 and into contact with an exposed conductor 207 of the signal wires 205, and a contact portion 215 that extend out of the opposite end of the cavity 211. The second connector 200 also includes second cavities 216 that receive ground terminals (not shown) that are connected at their upper ends to the drain wires 206 and at their lower ends to the chip member 104. The termination arrangement of this connector 200 also maintains, to the extent possible the geometry of the cables 204 through the connector termination, in the sense that the triangular arrangement of the three wires of each cable is maintained until the point where the drain wire is attached to the ground terminal and then the extent of the ground terminal is spaced from the ends of the signal wire terminals 212 as evidenced by the pattern of the first and second terminal cavities 211, 216.

[0061] FIG. 15 illustrates an alternate construction for use as a signal transmission line in accordance with the disclosure and takes the form of an extent of flat flexible circuitry 300. The extent includes a pair of signal conductors 302 that are spaced apart from each other and which run lengthwise between opposite ends of the cable 300. The conductors 302 are surrounded on their top and bottom surfaces and sides by insulative portions 304, 305. Ground shields 306 are provided to enclose the signal conductors 302, and although shown only as above and below the signal conductors 302, it will be understood that they may be disposed alongside of the signal conductors. With this sort of structure, the signal conductors may be exposed and aligned with terminal tails, while the ground shield extended to cover the termination areas in a manner similar to that shown above.

[0062] FIG. 16 is a graph comparing the loss between two 12-inch lengths of signal transmission lines, with one of the transmission lines comprising a pair of circuit traces formed in or on FR-4 circuit board material and the other transmission line comprising cables of the Present Disclosure. It can be seen from FIG. 16 that the use of the cable of the Present Disclosure leads to a very low loss transition that only breaks past the 5 dB mark at approximately the 20 GHz frequency. Within the range of testing error, we believe that the cables of the Present Disclosure have low loss characteristics of no greater than between about 5 dB and about 8 dB at frequencies greater than about 19 Ghz.

[0063] While a preferred embodiment of the Present Disclosure is shown and described, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the foregoing Description and the appended Claims.