Bonding discrete wires to form unitary ribbon cable

This invention is directed to a method and to a preferred 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.

BACKGROUND OF THE INVENTION 
This invention is directed to a method of bonding the entry ends of a 
plurality of discrete wires to form a unitary ribbon cable for insertion 
into and termination by an electrical connector, such as a modular plug. 
While the invention has diverse application for the preparation 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 load bar insert, or wire 
organizer, where the discrete wires were first loaded into such load bar 
insert to align and position the wires for eventual entry into the 
connector. However, problems still persisted with the use of such inserts, 
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 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. 
Pat. 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. Pat. No. 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, Pa. 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.degree. 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. Pat. 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. 
In a companion patent application, filed concurrently with this application 
by one of the inventors hereof, where such companion application was 
assigned U.S. Ser. No. (Attorney Docket 16012), an improved load bar 
insert is disclosed. The invention thereof, where the application is 
incorporated herein in its entirety, relates to an electrical connector, 
preferably a modular plug. A preferred embodiment of the invention of said 
companion application comprises a dielectric housing having a conductor 
receiving end, a conductor terminating end, a passageway communicating 
internally between the respective ends, and a spacing insert in the 
passageway to receive a plurality of conductors and to position same in a 
manner to achieve Category 5 performance levels in the modular plug. The 
insert is characterized by having an upper surface and a lower surface to 
receive or position selected pairs of the conductors. Within the limits of 
the housing, the insert maximizes the separation of the selected pairs and 
arranges them in plural planes before being realigned into a common plane 
for termination 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 rod like member, such as may be made of 
an elastomer, styrofoam, or plastic tube. A feature of this companion 
invention is the provision of separating the wires into plural planes, 
then bringing them together for loading into the modular plug. By 
incorporating the method of this invention, improved performance levels 
are ensured in a timely and cost efficient manner. 
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. 
SUMMARY OF THE INVENTION 
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.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
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. 
FIG. 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 FIG. 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. Nevertheless, the preferred approach 
lies in the use of this invention with a loading bar insert 22, as more 
fully taught in the companion application, and illustrated in FIGS. 1 and 
7. While the companion application discloses some alternative embodiments 
for the insert, ranging from a relatively solid body to a member with a 
low dielectric constant, hollow cylinder or shape, for example, the 
further discussion will be directed to the solid embodiment of FIGS. 1 and 
7. This alternate 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 FIG. 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 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 FIGS. 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 
FIGS. 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 FIG. 3. In the illustrations of 
FIGS. 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 FIG. 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 FIG. 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. 
FIGS. 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 0.040" 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.