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 replicate closely the geometry of the cable. The connector terminals are arranged in alignment with the cable signal conductors and shield extensions are provided so that shielding can be provided up to and over the termination between the cable signal conductors and the board connector terminal tails. Likewise, a similar termination structure is provided at the opposite end of the cable where a pair of terminals are supported by a second connector body and enclosed in a shield collar. The shield collar has an extension that engages the second end of the cable.

Description

34 38. Terminal housing 34 38 is then inserted into the via hole of the printed circuit board, where it couples to termination member.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Claims

1. A cable bypass assembly, the cable bypass assembly comprising:

a first connector, the first connector being configured for mounting to a circuit board, the first connector including a connector body, the connector body including a card slot and supporting a plurality of conductive terminals that extend into the card slot, the conductive terminals including contact portions and tail portions, the contact portions being held within the connector body card slot for contacting a mating blade of an opposing, mating connector, the tail portions extending out from the connector body rearward of the card slot;

an elongated cable, the elongated cable including:

a pair of signal conductors, the signal conductors being disposed within an insulative body portion of the elongated cable, the signal conductors extending, in a spaced-apart relationship, lengthwise through a body portion of the elongated cable,

a conductive shield, the conductive shield extending over an exterior of the elongated cable body portion,

an insulative outer covering, the insulative outer covering extending over the conductive shield, and

opposing first and second free ends, the first free end terminating directly to selected terminal tails of the first connector in a manner so that the signal conductors are in electrical communication with a pair of signal terminal tails;

a shield extension member, the shield extension member being configured to engage a first length of the conductive shield exposed at the first free end and extending therefrom over the signal conductors attached to the pair of signal terminal tails, the shield extension member including at least two spaced apart mounting feet; and

a second connector, the second connector including:

an insulative body, the insulative body supporting at least a pair of conductive signal terminals in a spaced-apart relationship, each conductive signal terminal including contact and tail portions wherein the second free end is connected to the tail portions of the at least a pair of terminals in the insulative body, and

a shielding collar, the shielding collar enclosing a body portion of the second connector, the shielding collar includes an extension portion, the extension portion engaging and receiving the conductive shield exposed at the second free end; wherein the cable bypass assembly is configured to support 10 GHz signaling.

2. The cable bypass assembly of claim 1, further including a second cable, the second cable including a pair of signal conductors, the second cable signal conductors disposed lengthwise therethrough in a spaced-apart relationship, the second cable signal conductors being attached to corresponding signal terminal tails of the first connector alongside the elongated cable.

3. The cable bypass assembly of claim 1, wherein the shield extension member further includes a cup portion, the cup portion being configured to receive the first free end therein.

4. The cable bypass assembly of claim 2, wherein the shield extension member further includes a pair of cup portions, each cup portion receivings receiving ends of the two cables therein.

5. The cable bypass assembly of claim 4, wherein the shield extension member includes at least three mounting feet, two of the mounting feet being disposed on opposing side edges of the shield extension member and a third of the three mounting feet being disposed between the cup portions.

6. The cable bypass assembly of claim 5, wherein the mounting feet and the two cable signal conductors are aligned with each other.

7. The cable bypass assembly of claim 1, wherein the tail and contact portions extend uninterruptedly lengthwise in a general horizontal plane through the first connector body.

8. The cable bypass assembly of claim 1, wherein the elongated cable includes a preselected length of flexible circuitry.

9. The cable bypass assembly of claim 1, A cable bypass assembly, the cable bypass assembly comprising:

a first connector, the first connector being configured for mounting to a circuit board, the first connector including a connector body, the connector body including a card slot and supporting a plurality of conductive terminals that extend into the card slot, the conductive terminals including contact portions and tail portions, the contact portions being held within the card slot for contacting a mating blade of an opposing, mating connector, the tail portions extending rearward of the card slot;

an elongated cable, the elongated cable including:

a pair of signal conductors, the signal conductors being disposed within an insulative body portion of the elongated cable, the signal conductors extending, in a spaced-apart relationship, lengthwise through a body portion of the elongated cable,

a conductive shield, the conductive shield extending over an exterior of the elongated cable body portion,

an insulative outer covering, the insulative outer covering extending over the conductive shield, and

opposing first and second free ends, the first free end terminating directly to selected terminal tails of the first connector in a manner so that the signal conductors are in electrical communication with a pair of signal terminal tails;

a shield extension member, the shield extension member being configured to engage a first length of the conductive shield exposed at the first free end and extending therefrom over the signal conductors attached to the pair of signal terminal tails, the shield extension member including at least two spaced apart mounting feet; and

a second connector, the second connector including:

an insulative body, the insulative body supporting at least a pair of conductive signal terminals in a spaced-apart relationship, each conductive signal terminal including contact and tail portions wherein the second free end is connected to the tail portions of the at least a pair of terminals in the insulative body, and

a shielding collar, the shielding collar enclosing a body portion of the second connector, the shielding collar includes an extension portion, the extension portion engaging and receiving the conductive shield exposed at the second free end, wherein the shielding collar further includes at least one through-hole terminal, the through-hole terminal extending from the shielding collar and engaging a through-hole of the circuit board.

10. The cable bypass assembly of claim 1, wherein the shielding collar further includes a cap portion, the cap portion having a cup portion formed therein, the cup portion being configured to receive an exposed second end of the cable therein and contact a length of exposed cable shielding.

11. The cable bypass assembly of claim 1, A cable bypass assembly, the cable bypass assembly comprising:

a first connector, the first connector being configured for mounting to a circuit board, the first connector including a connector body, the connector body including a card slot and supporting a plurality of conductive terminals that extend into the card slot, the conductive terminals including contact portions and tail portions, the contact portions being held within the card slot for contacting a mating blade of an opposing, mating connector, the tail portions extending rearward of the card slot;

an elongated cable, the elongated cable including:

a pair of signal conductors, the signal conductors being disposed within an insulative body portion of the elongated cable, the signal conductors extending, in a spaced-apart relationship, lengthwise through a body portion of the elongated cable,

a conductive shield, the conductive shield extending over an exterior of the elongated cable body portion,

an insulative outer covering, the insulative outer covering extending over the conductive shield, and

opposing first and second free ends, the first free end terminating directly to selected terminal tails of the first connector in a manner so that the signal conductors are in electrical communication with a pair of signal terminal tails;

a shield extension member, the shield extension member being configured to engage a first length of the conductive shield exposed at the first free end and extending therefrom over the signal conductors attached to the pair of signal terminal tails, the shield extension member including at least two spaced apart mounting feet; and

a second connector, the second connector including:

an insulative body, the insulative body supporting at least a pair of conductive signal terminals in a spaced-apart relationship, each conductive signal terminal including contact and tail portions wherein the second free end is connected to the tail portions of the at least a pair of terminals in the insulative body, and

a shielding collar, the shielding collar enclosing a body portion of the second connector, the shielding collar includes an extension portion, the extension portion engaging and receiving the conductive shield exposed at the second free end, wherein the second connector is configured to connect directly to a chip member.

12. A cable bypass assembly with low loss performance at high data frequencies, the cable bypass assembly comprising:

a first connector, the first connector being configured for mounting to a circuit board, the first connector including a connector body with a card slot, the connector body supporting a plurality of conductive terminals, the conductive terminals including contact portions and tail portions, the contact portions being held within the connector body card slot for contacting a mating blade of an opposing, mating connector, the tail portions extending out from rearward of the connector body card slot;

an elongated cable having, the elongated cable including:

first and second opposing ends,

a pair of signal conductors, the signal conductors being disposed within the elongated cable in a spaced-apart relationship and extending lengthwise through the elongated cable, and

at least one conductive shield, each conductive shield extending lengthwise through the elongated cable and substantially enclosing the signal conductors, the signal conductors, at the first end, being terminated directly to selected terminal tails of the first connector in a manner so that the signal conductors are in electrical communication with a pair of signal terminal tails along a horizontal extent thereof;

a shield, the shield extending over the signal conductors attached to the signal terminal tails, the shield including a pair of ground shields; and

a second connector, the second connector including an insulative body, the insulative body supporting at least a pair of conductive signal terminals in a spaced-apart relationship, each conductive signal terminal including contact and tail portions, the cable signal conductors at the second end thereof being terminated to the contact portions, and the cable at least one conductive shield being terminated to selected terminals of the second connector designated for ground purposes; wherein the cable bypass assembly is configured to support 10 GHz signaling.

13. The cable bypass assembly of claim 12, wherein the cable is an extent of flexible circuitry, the signal conductors including two signal conductors.

14. The cable bypass assembly of claim 13, wherein the ground shields are disposed on opposite sides of the signal conductors.

15. A cable bypass assembly, the cable bypass assembly comprising:

a first connector, the first connector being configured for mounting to a circuit board, the first connector including a connector body with a card slot, the connector body supporting a plurality of conductive terminals, the conductive terminals including contact portions and tail portions, the contact portions extending in the card slot for contacting an opposing mating connector;

an elongated cable, the elongated cable including:

a pair of signal conductors, the signal conductors being disposed within an insulative body portion of the elongated cable, the signal conductors extending, in a spaced-apart relationship, lengthwise through a body portion of the elongated cable,

a conductive shield, the conductive shield extending over an exterior of the elongated cable body portion,

an insulative outer covering, the insulative outer covering extending over the conductive shield, and

opposing first and second free ends, the first free end terminating directly to selected terminal tails of the first connector in a manner so that the signal conductors are in electrical communication with a pair of signal terminal tails;

a shield extension member, the shield extension member being configured to engage a first length of the conductive shield exposed at the first free end and extending therefrom over the signal conductors attached to the pair of signal terminal tails, the shield extension member including at least two spaced apart mounting feet; and

a second connector, the second connector including:

an insulative body, the insulative body supporting at least a pair of conductive signal terminals in a spaced-apart relationship, each conductive signal terminal including contact and tail portions, and

a shielding collar, the shielding collar enclosing a body portion of the second connector, the shielding collar includes an extension portion, the extension portion engaging and receiving the conductive shield exposed at the second free end, wherein the cable bypass assembly is configured to support 10 GHz signaling.

16. The cable bypass assembly of claim 15, further including a second cable, the second cable including a pair of signal conductors, the second cable signal conductors disposed lengthwise therethrough in a spaced-apart relationship, the second cable signal conductors being attached to corresponding signal terminal tails of the first connector alongside the elongated cable.