U.S. patent number 3,751,801 [Application Number 05/139,947] was granted by the patent office on 1973-08-14 for method and apparatus for terminating electrical ribbon cable.
This patent grant is currently assigned to Honeywell Inc.. Invention is credited to Everhardt P. Praeger, Brian A. Wolfset.
United States Patent |
3,751,801 |
Praeger , et al. |
August 14, 1973 |
METHOD AND APPARATUS FOR TERMINATING ELECTRICAL RIBBON CABLE
Abstract
A new termination, with which a miniature ribbon cable can be
connected readily to other electrical devices, has adjacent cable
conductors connected without fan-out to a connector plate having
contacts on opposite sides of a board-like insulator. The cable
insulation is removed from the conductors, prior to assembly of the
cable with the connector plate, preferably along the entire
conductor length that overlies the insulator.
Inventors: |
Praeger; Everhardt P.
(Framingham, MA), Wolfset; Brian A. (Framingham, MA) |
Assignee: |
Honeywell Inc. (Minneapolis,
MN)
|
Family
ID: |
26837702 |
Appl.
No.: |
05/139,947 |
Filed: |
May 3, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
750291 |
Aug 5, 1968 |
3605060 |
|
|
|
Current U.S.
Class: |
29/860;
29/879 |
Current CPC
Class: |
H01R
12/777 (20130101); H05K 1/117 (20130101); Y10T
29/49179 (20150115); H05K 2201/10356 (20130101); H05K
3/3405 (20130101); Y10T 29/49213 (20150115); H05K
2201/09154 (20130101) |
Current International
Class: |
H01R
12/00 (20060101); H01R 12/24 (20060101); H05K
1/11 (20060101); H05K 3/34 (20060101); H01r
043/00 () |
Field of
Search: |
;29/63A,63B,629,628
;174/88 ;339/17F,176F |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lanham; Charles W.
Assistant Examiner: Duzan; James R.
Parent Case Text
This application is a division of pending application Ser. No.
750,291, filed Aug. 5, 1968, now U.S. Pat. No. 3,605,060, owned by
the assignee hereof.
Claims
Having described the invention, what is claimed as new and secured
by Letters Patent is:
1. A method for terminating an electrical ribbon cable having
insulated electrical conductors disposed side-by-side, said method
comprising the successive steps of
A. removing the insulation from the ends of said conductors at a
first end of said cable,
B. forming said uninsulated conductor ends into first and second
rows spaced apart in the direction of the thickness of said
cable,
C. disposing the ends of a first array of electrical contacts along
said uninsulated conductor ends in said first row thereof, with
said first array of contacts being supported on an insulated board
fitted between said rows of conductor ends, and
D. disposing the ends of a second array of electrical contacts
under said uninsulated conductor ends in said second row thereof
where said second array of contacts are supported on an insulated
board having an edge fitted between said rows of conductor ends so
that said first and second arrays of contacts are disposed
back-to-back, and
E. electrically connecting said conductor ends in said first and
second rows thereof to said contacts in said first and second
arrays thereof, respectively.
2. A method as defined in claim 1 further characterized in that
said cable connectors are substantially cylindrical.
3. A method as defined in claim 1 further comprising the step of
encapsulating the adjoining ends of said cable and said
board-supported contact arrays with an insulating material.
4. A method as defined in claim 1 further characterized in that
said forming step disposes the ends of adjacent cable conductors in
different ones of said first and second rows.
5. A method as defined in claim 1 including the step of maintaining
the spacing between said conductor ends not substantially greater
than the spacing between the corresponding cabled conductors.
6. A method as defined in claim 1 wherein said step of forming
includes the steps of:
A. forming said first row of conductor ends in the same plane as
said cable; and
B. forming said second row of conductor ends in a plane parallel to
said plane of said first row of conductor ends.
7. A method as defined in claim 1 wherein said step of forming
includes the steps of:
A. providing said uninsulated conductor ends in said first row in
substantially the same plane as their corresponding insulated
conductors which are in a first plane; and
B. forming said uninsulated conductor ends in said second row in a
second plane substantially parallel to said first plane.
8. A method as defined in claim 7 wherein the distance between said
first and second planes is slightly greater than the thickness of
said insulated board.
Description
BACKGROUND
This invention relates to the connection of a miniature electrical
ribbon cable to other electrical elements. More particularly the
invention provides a ribbon cable with a new termination to which
other electrical devices can readily be connected. The invention
also provides a new method for terminating a miniature ribbon
cable. The termination and the method of preparing it provide a new
degree of cost saving and compactness for terminations for ribbon
cable having miniature fragile conductors in such close proximity
to each other that separate connection to each conductor has
heretofore been relatively impractical.
A ribbon cable is terminated, within the context of this invention,
by electrically and mechanically attaching the cable conductors to
an assemblage of contacts to which further connection can readily
be made. The further connection can be by plug-in or other readily
effected, removable connection and, alternatively, can be more
permanent as by soldering or welding.
Ribbon cable is electrical cable in which many conductors are
embedded in a flat ribbon-like insulator. The conductors are
generally arranged sideby-side in a single layer. Recently ribbon
cable of miniature dimensions, and further, miniature cable
dimensioned to operate as open wire transmission line, have been
desired for electrical equipment, such as for interconnecting
elements of a computer. However, use of such cables has been
severely restricted by difficulty in terminating the cable at
reasonable cost with a compact structure to which further
connection can be effected with ease A further problem is to
terminate transmission line ribbon cable without introducing
excessive impedance discontinuities.
One reason miniature ribbon cable is difficult to terminate is that
there is little space between adjacent conductors, typically there
are 30 conductors in a cable 3/4 inch wide. Further, the small size
(typically less than 10 mil diameter) and hence fragility of each
conductor introduces mechanical problems, particularly problems in
positioning and supporting the individual conductors during
automatic machine or manual manipulation. This latter problem has
generally been skirted in the prior art by leaving the conductor
ends embedded in the cable insulation until the final steps in the
termination process, or by requiring that extensions of the
conductors - beyond the point of termination - remain on the cable
until the terminating connections are secure. These and other prior
techniques such as are disclosed in U.S. Pat. Nos. 3,004,237,
3,355,669, 3,221,286, 3,149,897, 3,189,864 and 3,017,602 are not
satisfactory, especially with miniature cables of rod-like
transmission-line conductors, as distinguished from older, cables
having relatively widely-spaced ribbon-like conductors.
Accordingly, it is an object of this invention to provide a new
cable termination suited for economical use with miniature ribbon
cables, with ribbon cables operated as transmission lines, and with
ribbon cables of rod-like conductors.
Another object is to provide a termination for cable of the
foregoing types which is compact, and, further, which can be
attached with relatively simple and low cost equipment by
relatively unskilled labor.
Another object is to provide a cable termination of the above
character to which further connection can be made readily,
including by plug-in connector, by soldering, and by welding.
A further object is to provide such a cable termination that does
not require conductor fan-out, that is compact, and that introduces
relatively small impedance discontinuities into transmission line
cables.
It is also an object of the invention to provide an economically
practical method for terminating miniature ribbon cable,
transmission line ribbon cable, and ribbon cable having rod-like
conductors.
A particular further object is to provide such a method in which
surplus conductor insulation, or surplus conductor length, is not
required during fabrication of the termination.
Other objects of the invention will in part be obvious and will in
part appear hereinafter.
SUMMARY OF INVENTION
In general, the cable termination of this invention is formed by
removing the ribbon insulation from the end of the ribbon cable to
expose, uninsulated, the ends of the cable conductors. Alternate
ones of the uninsulated conductor ends are displaced relative to
each other in opposite directions in the direction of the cable
thickness. This forms the uninsulated conductor ends into two rows
spaced apart in the direction of the cable thickness with the ends
of adjacent conductors being in different rows.
A connector plate, illustratively in the form of a small printed
circuit board, is fitted on the cable end with the edge of the
plate seated between the two rows of preformed conductor ends. The
connector plate has contacts on both plate surfaces, with a contact
under each conductor end. The conductor ends are then soldered or
otherwise secured to the contacts. The termination can be
encapsulated or otherwise packaged as desired.
Connection to the cable is now easily effected by the use of
conventional connector structure contacting the contacts on the
connector plate.
The resultant termination is characterized, particularly when
compared to the ribbon cable termination of the above-noted Cole et
al U.S. Pat. No. 3,004,237, by having the cable insulation
terminate sufficiently short of the cable end so that the
conductors extend without insulation to, and along, the connector
board. Further, the termination is easily used on cables having
conductors so close together, or so otherwise arranged, that one
cannot readily "weave" the connector plate between the cable
conductors, whether insulated or not; such weaving is disclosed in
the Cole patent.
The present cable termination is well suited for use with ribbon
cable having cylindrical or other rod-like conductors, as used in
recently introduced ribbon cable constructed to operate as open
wire transmission line. The invention generally requires that the
uninsulated conductor ends be self-supporting in the sense that the
uninsulated conductor ends maintain the position of being preformed
into two rows as described above.
The invention accordingly comprises an article of manufacture
possessing features, properties and the relation of elements
exemplified in the article hereinafter described and further
comprises the several steps for making the article and the relation
of one or more of such steps with respect to each of the others
thereof, all as exemplified in the method hereinafter disclosed,
and the scope of the invention is indicated in the claims.
BRIEF DESCRIPTION OF DRAWINGS
For a fuller understanding of the nature and objects of the
invention, reference should be had to the following detailed
description taken in connection with the accompanying drawings, in
which
FIG. 1 is a perspective view, partly broken away, of a cable
termination embodying features of the invention;
FIG. 2 is a plan view of a ribbon cable illustrative of those with
which the invention can be practiced;
FIG. 3 is a plan view of the cable of FIG. 2 with the insulation
removed from an end thereof and, further, of a connector plate for
use in making the termination of FIG. 1;
FIG. 4 is a side elevation view of the cable end and connector
plate of FIG. 3 with the uninsulated conductor ends formed into two
rows illustrative of the practice of the invention; and
FIGS. 5 and 6 show respectively side elevation and end views of
processing equipment for forming the conductor ends into two rows
as shown in FIG. 4.
DESCRIPTION OF ILLUSTRATED EMBODIMENT
In FIG. 1, the termination 10 on ribbon cable 12 has the cable
conductors 14 soldered to contacts 16 carried on a connector plate
18. An insulating encapsulation 20 is molded over the adjacent ends
of cable 12 and plate 18 to secure these elements together
mechanically and thereby minimize stress applied to the conductor
ends 14a that interconnect the plate and cable. The encapsulation
also facilitates attaching a conventional connector to the
connector plate 18 to effect further connection to the cable
12.
The cable 12 has a substantial number of conductors 14 disposed
side-by-side embedded in a ribbon of insulation 22. It is the
general practice that this is a unitary insulation formed over all
the conductors simultaneously; the individual conductors normally
do not have, in addition, individual insulating jackets. On the
other hand, the conductors alternatively could be individually
insulated and bonded side-by-side to provide the cable
configuration. The illustrated conductors 14 are cylindrical and
the illustrated cable is designed so that adjacent conductors
operate as open wire transmission line. The illustrated cable also
has miniature dimensions. For example, in one embodiment, the
conductors have 8 mil diameters, are spaced apart on 25 mil
centers, and are embedded in insulation 33 mils thick. The
insulation 22 is typically a synthetic resin of high loss and low
electric permitivity; trichlorofluorethylene (commercially
available under the trademark Teflon) is a preferred insulator
although it has such a high melting point that it cannot be melted
away with conventional soldering equipment.
As shown in FIGS. 2 and 3, the first step in fabricating the FIG. 1
termination 10 with a trimmed cable 12 as shown in FIG. 2 is to
remove the insulation 22 from the conductor ends 14a, as shown in
FIG. 3. This can be done with conventional skills, as by thermally
softening the insulation to be removed and then removing it from
the end of the cable 12. The technique selected often depends on
the nature of the insulation 22.
In the event the conductor ends 14a are bent or otherwise
misaligned after having the insulation stripped terefrom, they are
next straightened by pulling them through a comblike structure or
with equivalent techniques so that the conductor ends are straight
and aligned as in FIG. 3.
The conductor ends are next formed into two rows 24 and 26 as shown
in FIG. 4 with adjacent conductor ends being in different rows, as
shown also in FIG. 1. The two rows 24 and 26 are spaced apart, in
the direction of the thickness of the cable 12, sufficiently to
receive between them the connector plate 18 shown in FIGS. 1, 3 and
4 and described further below. As indicated, the rows 24 and 26 are
essentially parallel to the side-by-side arrangement of the
conductors 14 in the cable 12. It should be noted that the
illustrated conductors are not fanned apart in the plane of FIG. 3;
on the contrary, in this plane and in the plane parallel to the
cabled conductors and transverse to the plane of the ribbon cable,
the conductor ends remain in-line with the cabled conductors.
The cable ends can be staggered to form the two rows 24 and 26 by
laying the cable on a flat support bed 28 shown in FIG. 5. The
conductor ends 14 lie in slots 30 and 32 of a stamping form 34. The
slots 30 and 32 are aligned parallel to each other in-line with the
cabled conductors 14 but, as shown in FIG. 6, the alternate slots
32 are shallower than the intervening alternate slots 30 by the
amount of offset desired between the conductor rows 24 and 26 (FIG.
4). The bases of the slots 30 are substantially in the same plane
as the support bed 28, and the bases of slots 32 are above this
level.
As also shown in FIGS. 5 and 6, with the cable thus disposed, a
stamping die 36 having alternate long and short forming teeth 38
and 40, respectively, is pressed against the stamping form 34 with
the teeth 38 and 40 respectively meshing into the slots 30 and 32
to press alternate ones of the conductor ends 14a into the slots 30
and the other alternate conductor ends into the slots 32. The teeth
38 on stamping die 36 are dimensioned to position the conductor
ends at the bases of the deep slots 30 on the stamping form 34, and
similarly, the stamping die teeth 40 are dimensioned to press the
conductor ends lying in slots 32 to the bases of these slots.
The stamping die 36 also has a platen 47 that overlies the support
bed 28 and presses the cable 12 to the bed 28 as the teeth 38 push
conductor ends down into slots 30. Further, the illustrated die 36
has a cutting edge 46 that moves down closely spaced from the
forward face 48 of the stamping form to trim off excess conductor
lengths extending forward, out of the slots 30, 32 beyond the face
48.
With further reference to FIGS. 3 and 4, which show the alignment
of the connector plate 18 relative to staggered conductor ends 14a
prior to assembly of the plate with the cable, the illustrated
connector plate is a dielectric board 42 having contacts 16 secured
to the opposite "plate" surfaces thereof The board 42 and contacts
16 are conveniently of conventional printed circuit construction
and the board 42 generally can have the same width as the cable 12.
The contacts extend across the length of the board 42 from its
forward end 42a to the back end 42b that is adjacent to the cable
insulator 22 in the assembled termination. Further, the contacts 16
are so spaced apart on each side of the board 42 that each contact
is aligned under a different conductor end when the connector plate
is assembled with the cable, as shown in FIG. 1.
The connector plate 18 and cable 12 are assembled simply by
inserting the back end 42b of the board between the two rows of
conductor ends so that the end 42b is closely spaced from the edge
of the cable insulation 22, FIG. 1. This assembly is conveniently
carried out by placing the cable on a support plate in order to fix
the position of the rows 24 and 26 of conductor ends. The connector
plate is slid, toward the cable and between the rows of conductor
ends, guided on rails that position the plate with respect to the
width and thickness dimensions of the cable and hence relative to
the rows of conductor ends.
With the connector plate 18 thus assembled with the cable 12, one
row 24 of conductor ends overlays the contacts 16 on one side of
the board 42 and the other row 26 of conductor ends overlays the
contacts on the other side of the board 42. Further, each conductor
end is disposed substantially above the center of a contact.
The conductor ends are then attached and electrically connected to
the contacts as by reflow soldering. A preferred technique is to
heat the assemblage with infrared energy to cause a solder
pretinned on the contacts 16 to flow and bond to the overlying
conductor ends 14a, which can also be pretinned. Because the
contacts 16 on each side of the plate 14 are on center-line
spacings twice as large as the conductor-to-conductor center-line
spacing in the cable, sufficient space can be provided between
adjacent contacts so that solder does not "bridge" between two
adjacent contacts causing an undesired short circuit.
The final step in the assembly of the termination 10 is to mold or
otherwise form the encapsulation 20 (FIG. 1) bridging the adjacent
ends of the cable 12 and the connector plate 18. The forward
portion of plate 18 extends beyond the encapsulation 20 (toward the
board forward edge 42a) so that the contacts thereon can be engaged
for connecting the cable 12 to other devices. A thermosetting
synthetic resin material is preferred for the encapsulation 20. The
encapsulation serves to join the conductor plate and cable
insulation mechanically, thereby relieving the conductors that
extend between the connector plate and the cable insulation from
being stressed by manipulation and use of the terminated cable. The
encapsulation also provides mechanical and electrical protection
for the termination, and as previously noted, facilitates plugging
the end of the connector plate protruding from the encapsulation
into a mating conventional connector.
It will thus be seen that the object set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in carrying out the
above method, in the described article, and in the construction set
forth, without departing from the scope of the invention, it is
intended that all matter contained in the above description and
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which is a matter of language, might be said to fall
therebetween.
* * * * *