AU688593B2 - Bonding discrete wires to form unitary ribbon cable for high performance connector - Google Patents

Description

BONDING DISCRETE WIRES TO FORM UNITARY RIBBON CABLE FOR HIGH PERFORMANCE CONNECTOR

This invention is directed to a method of bondinr the entry ends of a plurality of discrete wires to fo. ■ a unitary ribbon cable for insertion into and termination by an electrical connector, such as a modular plug, and to the enhancement of such connector by the use of a load bar insert to improve performance through a reduction in crosstalk. A current standard or performance level used today is identified as Category 5 products where operating frequencies may be 100 MHz or higher. While the invention has diverse application for the preparation and alignment of wires to be terminated within a connector, it has particular utility with the loading of modular plugs which often must be terminated in the field by technicians, or in small factory operations manually. A first approach introduced several years ago was the use of a wire organizer, where the discrete wires were first loaded into such wire organizer to align and position the wires for eventual entry into the connector. However, problems still persisted with the use of such organizers, as free ends of the wires still had to be directed to an assigned passageway in the connector, and stubbing of the end could result.

While the application of this invention is broad, for convenience, the further description will be directed to the field of modular plugs, a product well known in the art, and the applicability of the invention hereof as it relates to the loading and performance enhancement of a modular plug. Modular plugs, a relatively inexpensive electrical connector, are used extensively in telephonic and other data communication systems. Frequently such plugs must be terminated in the field by technicians, or in a factory by assemblers fabricating patch cords. Typically the cable to be terminated in the plug is a bundle of four twisted pair, insulated, multi-colored wires (eight in total) , within a cable jacket or wrap of an insulating sheath. The bundle may optionally include a surrounding shield or a drain wire for use in a shielded plug. In any case, to prepare the cable for eventual termination in the plug, the cable jacket is peeled back to expose the various insulated pairs. Thereafter, with the several insulated wires exposed, the wires are untwisted and arranged in the desired order, generally in a side-by-side fashion. The wires are then individually inserted into the connector housing and terminated by an insulation piercing blade, a termination procedure known in the art. Recognizing these cumbersome procedures, load bar inserts were developed to facilitate the loading process. A typical loading bar insert is illustrated in U.S. Patent No. 4,713,023. The invention thereof includes a wire positioning means for holding insulated conductors in an array so that the ends thereof are presented in alignment below terminal receiving cavities when the wire loaded positioning means is in the housing. The positioning means includes cam means formed thereon and adapted to engage a housing strain relief section when it is moved downwardly, whereby the positioning means is moved forwardly in the housing to fully seat the positioning means therein and position the free ends of the insulated conductors below the terminals.

In UK Patent Application NO. 2 249 222A, assigned to the assignee hereof, there is taught an electrical connector and insert therefor, where the invention relates to a plastic insert for such connector and has a row of wire guiding mouths each for guiding an individual wire into a passageway as the cable is inserted into the connector. The cable has at least one wire less than the number of the passageways and the insert has at least one solid blanking-off portion for blanking off the single or plural unused passageways. The wire guiding mouths of the insert are defined by at least one longitudinal opening having scalloped longitudinal edges. U.S. Patent 4,601,530, assigned to the assignee hereof, teaches a preloaded wire organizer for a modular type plug. Specifically, the patent teaches the process of preloading wires into a wire holder which locates the leading ends of the wires at the same pitch as passageways in the connector housing. The wire holder, supported by the wires, is then inserted into and along a mouth of the housing until it abuts a tapered throat at the entrance to the passageways. Further advance of the bundle feeds the discrete wires through the wire holder into the respective passageways guided by the throat, while the wire holder remains adjacent the tapered throat.

In a recent development that utilizes a load bar insert for use with a modular plug, while offering improved performance at Category 5 levels, a performance level known in the art, was introduced by Stewart Connector Systems, Inc. of Glen Rock, Pennsylvania. They introduced a Category 5 performing modular plug utilizing a sliding wire management bar, where such bar contains two rows, each with four through holes, to receive the standard eight wires of a cable. To use the management bar, the user is advised to arrange the wires in two equal sets, and cut each set of four at a 45° angle such that no two wires are of the same length. With the prepared wires, the wires are individually fed into the holes of the wire organizer, in sliding engagement therewith, then trimmed to the same length. For the loading step, the wire organizer is first pushed to the end of the trimmed wires, then inserted into the connector housing. In the fashion of U.S. Patent No. 4,601,530, when the wire organizer can no longer move forward, the wires are pushed beyond the wire organizer into a position to be individually terminated, as known in the art. While claiming to provide Category 5 performance, the assembly and termination of the modular plug is very labor intensive. The procedure by which this invention supports the performance and loading of the modular plug of the companion application, and its ability to generally improve the speed in which modular plugs may be factory terminated, will become apparent in the description which follows, particularly when read in conjunction with the accompanying drawings.

This invention is directed to the field of electrical connectors, such as a modular plug, where a plurality of insulation jacketed wires are inserted into and terminated within the plug, where one such termination procedure is by insulation piercing. The method of this invention is particularly directed to a procedure for aligning and bonding, such as by heat, adhesive or tape, a plurality of discrete insulation jacketed wires to facilitate the handling and insertion of the wires into a modular plug housing, for example, where they are terminated. The steps in bonding by heat comprise aligning the plural wires in side-by-side fashion on a first fixture, where the fixture includes a plurality of heating elements, with each heating element arranged to contact the insulation jackets of an adjacent pair of the wires. Thereafter, aligning a second fixture of comparable design and function in sandwich fashion to the opposite sides of the insulation jacketed wires, and applying electrical current to the heating elements to effect a localized melting and bonding of the insulation jackets of adjacent wires to one another. By this procedure a unitary ribbon type cable is formed which facilitates its handling and termination. As an optional feature hereof, to enhance the performance of the connector, a load bar insert may be provided down stream of the bonded wire ends. A preferred load bar insert is characterized by having an upper surface and a lower surface to space or separate selected pairs of the conductors. Within the limits of the connector or plug housing, the insert or spacing maximizes the separation of the selected pairs and arranges them in plural planes before being realigned upstream into a common plane for bonding and terminating at the conductor terminating end. A first embodiment includes grooves in the upper and lower surfaces of the insert, while a second embodiment is directed to a spacing rod like member, such as may be made of an elastomer, plastic, or plastic-like tube.

FIGURE 1 is an exploded perspective view of an electrical connector, such as a modular plug, for example, in which the procedure of the present invention has been practiced, further illustrating the use of a performance enhancing load bar insert.

FIGURES 2 to 4 are transverse sectional views illustrating the sequence for bonding discrete wires to form a uniform ribbon cable according to this invention. FIGURES 5 and 6 are lateral sectional views corresponding to the sequences illustrated in Figures 2 and 3, respectively.

FIGURE 7 is a lateral sectional view of the assembled modular plug illustrated in Figure 1. FIGURE 8 is a sectional view taken through line 8-8 of Figure 7.

FIGURE 9 is a perspective view of the load bar insert of Figure 1, illustrating a pre-loading condition thereof, with the discrete conductors poised for lacing therein.

FIGURE 10 is a sectional view of a prior art cable, taken along line 10-10 of Figure 1, showing plural conductors prior to a planar arrangement thereof for entry into the load bar insert of Figure 9.

FIGURE 11 is a sectional view of a preferred load bar insert of this invention, taken along line 11-11 of Figure 1.

FIGURE 12 is a sectional view, taken along line 12- 12 of Figure 1, showing the realigned conductors in a planar relationship for entry into a modular plug, for example, prior to termination therein. FIGURE 13 is a perspective view of a second embodiment for a load bar insert, where such load bar insert is optionally removable.

FIGURE 14 is a perspective view similar to Figure

13, showing a third embodiment where no insert is used, but rather a spacing is provided with the wires arranged for separation.

FIGURE 15 is an enlarged, longitudinal sectional view, similar to Figure 7, showing in phantom lines the position of the load bar of Figures 13 and 14.

This invention relates to a procedure for bonding plural, discrete, insulated wires to form a unitary ribbon cable, and to the product thereof. More particularly, the invention is directed to a cost effective method for manual factory wiring of a modular plug, for example, and to the optional use of a load bar insert to enhance performance of the modular plug.

Figure 1 illustrates a prime example of how the method of this invention can simplify the loading and termination of a modular plug. A typical electrical connector 10, as shown in Figure 1, comprises an insulating housing 12 formed with an open end 14 for receiving a multi-wire electrical cable 16, a terminating end 18 communicating with a row of cable wire receiving passageways. The passageways further communicate with an internal cavity 20 opening into end

14. By way of further understanding, the multi-wire electrical cable 16 is characterized as twisted pair cable, where preferably selected pairs of wires are twisted together. That is, a typical cable for an 8- position modular plug will reveal four twisted pairs of insulated wires. By way of further example, under specification TIA/EIA-568A, a preferred pairing arrangement of conductors or wires for the modular plug terminal numbers is as follows: 1-2, 3-6, 4-5, and 7-8. As noted previously, this invention has utility in the loading of fine wires to electrical connectors, with or without the assistance of a loading bar insert or wire organizer, as hereinafter explained. Nevertheless, the preferred approach lies in the use of this invention with a loading bar insert 22, and illustrated in Figure 1 and later Figures. While there are variations or embodiments for the load bar insert, ranging from a relatively solid body to a member with a low dielectric constant, hollow cylinder or shape, for example, the further discussion insofar as it relates to the bonding procedure, will be directed to the solid embodiment of Figures 1 and 7. This preferred embodiment of an insert, molded or formed of a rod or shaped body, includes upper and lower surfaces 24, 26, respectively, a back 28, and a tapered or divergent forward surface 30 directed to the cable receiving passageway 32 underlying the conductor terminating blades or terminals 23, see Figure 7. Along the respective upper and lower surfaces 24, 26, are pairs of slots or grooves 34, 36, respectively, into which selected pairs of wires 38 are laced or received. To carry on with the pairing arrangement above, pairs 3-6 and 7-8 are seated within upper slots 34, while the remaining two pairs are seated within lower slots 36. Note further that the upper slot containing pair 3-6 includes an end divider 40, to separate and align the wires into their numerically assigned position for termination. Once the selected pairs are positioned within the insert, or the insert is omitted, the discrete, insulated wires 1 to 8 are positioned between a sandwich like bench fixture 44 illustrated in Figures 2 to 6, a preferred practice in bonding the discrete wires. In any case, the pair of fixtures may each comprise a planar body 46 having plural, parallel resistance heating elements 48 arranged along the mating surfaces 50. As best seen in Figures 5 and 6, the opposite surface 52 includes means 54 for supplying electric current to the heating elements 48 to effect heating thereof. The heating elements 48 are positioned to lie between adjacent side-by-side wires, and to the outside thereof, see Figure 3. In the illustrations of Figures 2 to 4, if the number of wires is "n", the number of heating elements is "n + 1". With the respective fixtures positioned in a compressive relationship to the discrete wires, note the direction arrows of Figure 3, electrical current may be applied to the heating elements 48 by means 54 to effect melting and bonding of the insulated wires into a unitary ribbon cable at the end thereof. That is, the respective fixtures 44 are brought together to trap and locate the discrete wires exactly on the preferred 0.040" centerlines, where the heating elements 48, such as nichrome heating wires, are also spaced on 0.040" distances. By this arrangement, including the outermost heating elements, the heating elements act as miniature "V" blocks. With the fixtures separated, note the direction arrows of Figure 4, it will be seen that the wires are bonded, and that a scalloped profile 55 is revealed. Thereafter, the bonded wires are trimmed laterally through the scalloped profile to present a unitary member for insertion and termination within the modular plug. This profile offers a further advantage to the insertion and termination procedure, as hereinafter explained. Another advantage in the use of this type of fixture is the rather quick cool down of the system which allows for a rapid turnaround in repeating the operation with a new and different set of wires.

Figures 7 and 8 illustrate an inserted and preterminated unitary member in a modular plug, where the bonded wires are positioned under the plural terminating blades 23. The passageways 32 into which the bonded wires are received are typically a series of circular communicating sections, where the upper and lower surfaces are scalloped 60, and the sections are separated by two spaced apart opposing ribs 62. With a conventional discrete wire insertion, where the wire is not precisely aligned with the passageway, stubbing can occur. However, with the present invention, where the bonded web between adjacent wires has been modified by the newly impressed profile 55, stubbing problems are greatly minimized. Also, by reshaping or changing the wire profile, it is now possible to use larger diameter wires than heretofore possible. That is, the molded impressions from the scalloped profile 55 create clearances which ease the insertion process and even allow the use of wires exceeding 0.040" diameter, for example.

In accordance with a preferred procedure for practicing this invention, a fixture was prepared using a printed circuit board with nine SST wire loops arranged on .040" centerlines, the same spacing as the insulated wires, in parallel fashion. With a pair of such fixtures arranged in sandwich fashion to eight insulated wires, a current of 7 to 10 amps at from 5 to 2 seconds was applied to the SST wire loops to effecting bonding of the insulated wires. After trimming, the bonded wires were readily inserted into a modular plug. Alternate procedures are available to effect bonding of the wire ends. For example, while the wires are positioned in side-by-side fashion in a suitable fixture, an adhesive or tape may be applied to such ends to present a unitary ribbon cable at least at the end thereof. However, these alternate approaches do not offer the advantage of reshaping the wire ends as will be found in the heat bonding procedure. Turning now to the load bar insert in its several embodiments, as illustrated in Figures 1,7,9 and 11-15, it should again be noted that this is an optional feature to the wire bonding noted above. However, before continuing with a description of this optional feature, some brief background may be helpful. As known in the art, the multi-wire electrical cable 16, shown in section in Figure 10, is characterized as twisted pair cable, where preferably selected pairs of wires 38 are twisted together. That is, a typical cable for an 8-position modular plug will reveal four twisted pairs of insulated wires. By way of further example, under specification TIA/EIA-568A, a preferred pairing arrangement of conductors or wires for the modular plug terminal numbers are as follows: 1-2, 3-6, 4-5, and 7-8. This will be discussed in more detail hereinafter.

Nevertheless, it should be noted that under prior art practices it was believed that in the preparation and termination of the wires in a modular plug, the "1/2 inch untwist" rule had to be followed. That is, the twisted pairs had to remain twisted except for about 1/2 inch of the end of each of wire to effect termination. It was discovered that such rule for modular connectors can be violated by the practice of the optional feature hereof without suffering an increase in Near End Crosstalk (NEXT) . A critical factor is that the physical separation of the interfering pairs (primarily the 3-6 pair which is split around the 4-5 pair in the center of the plug) is more important than maintaining a tight twist. Crosstalk is inversely proportional to the distance between the interfering wires.

Continuing with the remaining Figures, Figure 9 illustrates a first embodiment of a load bar insert 22, adapted to be slidable received through opening 14 within the housing 10. This preferred insert, formed from a dielectric material, was described above. Note by providing for the upper and lower slots, separation of the wires is maximized within the housing 10. Further, by providing for the forward or diverging surface 30, the respective wire pairs along the upper surface 24 are in multiple planes before returning to a single plane, as shown in Figure 12. These factors contribute significantly to the improved performance of the plug, since crosstalk is reduced by increasing the wire separation distance.

A second embodiment for a load bar insert 64 is illustrated in Figures 13 to 15, with the primary purpose of the insert being to space-apart the wires into multiple planes prior to realignment for purposes of termination, this new insert satisfies well such purpose. The insert 64 comprises a spacing member, which may be an elastomer, styrofoa , or plastic cylinder, where the selected pairs of wires are placed either over the top or under the bottom. In the illustration of Figure 13, the critical pair 3-6 is along the top while the remaining pairs are below the insert. Specifically, in the different embodiments the wire divergence pattern is varied. Howev. , a common feature thereof is the provision that the critical pairs 3-6 and 4-5 are separated. By the use of a spacing member, the wires, when inserted into the connector housing, are maintained at a spacing to minimize crosstalk.

With the two embodiments illustrated in the several Figures, it will be seen that after the wires engage the insert 22,64, the respective wires, in the desired sequence, converge from their respective planes to a common plane for termination. It was discovered that insertion of a unitary braid of side-by-side wires could more easily be inserted into the passageways of a connector housing than a number of discrete wires. This recognition resulted in the wire bonding technique described above.

There is an obvious advantage that can be attributed to the combination of the wire bonding procedure and the performance enhancing feature. According to the wire bonding procedure described earlier, the wires after bonding are relatively fixed to one another. This advantage may be best illustrated by Figure 14 where the rod or cylindrical like insert 64 has been removed. Since the wires are fixed in position at the respective ends, i.e. within cable 52 and bonded zone 66, the wires will not resile into a common plane as would be expected with only one fixed end. Thus, the wires when bonded, such as described above, may be readily inserted into the connector as discussed above. Figure 15 illustrates the relative position of the wires with or without the insert 64.

Claims

1. A method of aligning and bonding a plurality of discrete insulation jacketed conductors to facilitate handing and insertion of said conductors into an electrical connector housing to be electrically terminated therein, said method comprising the steps of

(a) selecting plural discrete insulation jacketed conductors arranged in at least two different planes,

(b) arranging and aligning the ends of said plural conductors in side-by-side fashion in a common plane on a first fixture, and

(c) bonding the insulation jackets of adjacent said ends to form a unitary ribbon type cable for ease of handling and termination.

2. The method according to claim 1 wherein said bonding is by a procedure selected from the group of heat, adhesive or taping.

3. The method according to claim l wherein bonding is by heat and said insulation jacketed conductors are initially circular in configuration, and that said heat changes said configuration through displacement of a portion of said insulation.

4. The method according to claim 3 wherein said heat is derived through heating elements arranged along said fixture.

5. The method according to claim 4 wherein said the number of conductors is "n" and the number of said heating elements is at least "n + 1".

6. A method of aligning and bonding a plurality of discrete insulation jacketed conductors to facilitate handling and insertion of said conductors into an electrical connector housing to be electrically terminated therein, said method comprising the steps of (a) aligning said plural conductors in side- by-side fashion on a first fixture, where said fixture includes a plurality of heating elements, with each heating element arranged to contact the insulation jackets of an adjacent pair of said conductors,

(b) aligning a second fixture of comparable design and function in sandwich fashion to the opposite sides of said insulation jacketed conductors, and

(c) applying electrical current to said heating elements to effect a localized melting and bonding of the insulation jackets of adjacent conductors to one another, whereby to form a ribbon type cable for ease of handling and termination.

7. A wire bonding fixture for bonding a plurality of discrete, parallel, insulated wires to form a unitary ribbon cable at the end of said wires, said fixture comprising a pair of essentially planar, dielectric members for compressively engaging said wires, heating elements arranged in parallel fashion along opposing major surfaces of said planar members, where the number of said wires is "n", and the heating elements are at least "n + 1", and that the internal heating elements contact the insulation of two adjacent wires, and means to heat said heating elements to effect a bonding of said insulated wires into a unitary member.

8. An electrical connector of the plug assembly type for mating with a receptacle type connector, where a plurality of conductors are terminated therein for electrical engagement with corresponding contacts in said receptacle, said plug assembly comprising a dielectric housing having a conductor receiving end, a conductor terminating end, a passageway communicating internally between said respective ends, and a spacing insert in said passageway to receive said plurality of conductors and to position same in a manner to improve the crosstalk performance of the plug assembly, said insert having an upper surface and a lower surface with plural grooves arranged along said surfaces to receive selected pairs of said conductors.

9. The electrical connector according to claim 8 wherein said insert includes a tapered wall facing said conductor terminating end, whereby said selected wires of conductors along said upper surface are directed toward and between the selected pairs of conductors along said lower surface.

10. The electrical connector according to claim 9 wherein the free ends of said conductors are arranged in a parallel manner in a common plane and bonded at said conductor terminating end.

A method and fixture for aligning and bonding a plurality of discrete insulation jacketed conductors to facilitate handling and insertion of the conductors into an electrical connector housing to be electrically terminated therein. The method comprises the steps of selecting plural discrete insulation jacketed conductors arranged in at least two different planes, arranging and aligning the ends of plural conductors in side-by-side fashion in a common plane on a fixture, and bonding the insulation jackets of adjacent wire ends to form a unitary ribbon type cable for ease of handling and termination. A preferred bonding procedure is by the application of localized heat to the wire ends to effect a melting and bonding of the insulation jackets.

Optionally, a performance enhancing load bar insert may be incorporated between the conductors down stream from the wire ends, whereby to separate such conductors and reduce crosstalk.

(Designated Figure 1)