US 3772775 A
In the preferred embodiment, a plurality of flat conductors are arranged in spaced parallel relation and encased in a dielectric covering to form a flexible flat conductor cable. At selected intervals along the length of this cable, a pair of spaced abrasive wheels are moved in a direction normal to the cable's length for removing pairs of spaced strips of insulation from one side of the dielectric cover. An electrical connector is then mounted on the flat conductor cable at each of these selected intervals. This electrical conductor comprises an elongated housing having an elongated U-shaped spring contained therein, with the opposed faces of the arms of the U-shaped spring underlying an axial slot formed in the top of the elongated housing. The electrical connector is mounted on the cable by removing its top portion to expose the upper end of the elongated spring and pushing a loop of the cable between the arms of the U-shaped spring such that the spaced strips of exposed conductors coincide with the opposed faces of the loop. Finally, the top portion of the electrical connector is replaced.
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Description (OCR text may contain errors)
United States Patent Bonnke et a1.
[ Nov. 20, 1973 METHOD OF MAKING FLAT CONDUCTOR CABLE ASSEMBLIES  Inventors: Hans R. Bonnke, Schaumburg,
Robert J. Melcher, Itasca, both of 111.
 Assignee: Methods Electronics Inc., Chicago,
 Filed: July 17, 1972  Appl. No.: 272,384
 US. Cl. 29/628, 29/629  Int. Cl 1101r 43/00  Field of Search 29/624, 628, 629; 339/17 F, 174 MP, 176
 References Cited UNITED STATES PATENTS 3,084,302 4/1963 Braeutigam 339/17 3,696,319 10/1972 Olsson 339/17 F 3,614,707 10/1971 Kaufmann 339/17 F 3,102,767 9/1963 Schneck 339/176 3,239,916 3/1966 Love 29/155.5
3,059,211 10/1962 Thomas et al 339/126 3,144,288 4/1964 Grant 339/17 3,350,530 10/1967 Fry 200/166 3,461,221 8/1969 Herb 174/84 Primary ExaminerCharles W. Lanham Assistant Examiner-James R. Duzan Attorney-John A. Dienner et al.
[5 7 ABSTRACT In the preferred embodiment, a plurality of flat conductors are arranged in spaced parallel relation and encased in a dielectric covering to form a flexible flat conductor cable. At selected intervals along the length of this cable, a pair of spaced abrasive wheels are moved in a direction normal to the cables length for removing pairs of spaced strips of insulation from one side of the dielectric cover. An electrical connector is then mounted on the flat conductor cable at each of these selected intervals. This electrical conductor comprises an elongated housing having an elongated U-shaped spring contained therein, with the opposed faces of the arms of the U-shaped spring underlying an axial slot formed in the top of the elongated housing. The electrical connector is mounted on the cable by removing its top portion to expose the upper end of the elongated spring and pushing a loop of the cable between the arms of the U-shaped spring such that the spaced strips of exposed conductors coincide with the opposed faces of the loop. Finally, the top portion of the electrical connector is replaced.
2 Claims, 4 Dim Figures PATENIEDuuvzo I975 III!" IIIIIIIII IIIIIIIIIIIIII'IIIIIIII III ITT' J /2 a a ,4
III IIIIII I METHOD OF MAKING FLAT CONDUCTOR CABLE ASSEMBLIES BACKGROUND OF THE INVENTION This invention related to an electrical conductor assembly comprising a flat conductor cable on which is mounted a plurality of electrical connectors at selected space intervals.
The present state of the art of making electrical conductor cable assemblies is disclosed by Schneck US. Pat. No. 3,102,767. In this patent, the flat conductor cable which is encased in a dielectric covering has a large strip (of the order of inch) removed from one side of the dielectric covering to expose the electrical conductors. This exposed area of the cable is then bent into a loop and the loop portion is pushed into the center of an elongated U-shaped spring carried inside of an elongated electrical housing, with the exposed area of the conductors extending the entire length of the loop portion.
The loop of exposed conductors formed in the manner disclosed by the Schneck Patent is objectionable for a number or reasons. The principle reason is that there is a possibility the exposed conductor portion will separate from the dielectric covering and contact adjacent conductors to cause a short circuit condition. Also foreign material will collect at the base of the loop portion of the cable having a detrimental effect on the conductance values of the conductors in the cable.
One solution to prevent the short circuit condition is to add an adhesive material to the dielectric covering of sufficient mechanical strength to hold the conductors in place even though one side of the dielectric covering is removed at the loop portion. This solution, of course, adds to the cost of the manufacturing the cable conductors since another material must be added in making the cables.
This invention avoids the above mentioned disadvantages of the Schneck disclosure. This is accomplished by providing two relatively narrow strips of exposed conductors which are spaced apart a selected amount to provide two points of contact. By reducing the amount of insulation removed from the cables, the chance of contamination of exposed conductors is greatly reduced, and likewise the cost of gold-plating the conductors is reduced with no loss of integrity of the part. The foreign material which collects at the base of the loop portion can no longer cause problems since this base section is now covered by a dielectric material.
DESCRIPTION OF DRAWING For a better understanding of this invention reference may be made to the accompanying drawing, in which:
FIG. I is a top plan view of a flat conductor cable constructed in accordance with the principles of this invention;
FIG. 2 is a cross sectional view of a portion of FIG. 1 taken along the line 2-2 in FIG. 1;
FIG. 3 is enlarged side view of the pair of strips removed from one side of the cable of FIG. 1; and
FIG. 4 is a cross sectional view showing the loop portion of the cable of FIG. 1 mounted in an electrical connector.
DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, there is shown a flat flexible electrical cable generally designated by the reference numeral 10, which comprises a plurality of generally straight electrical conductors 12 arranged in closely spaced parallel relation and encased in a dielectric covering 14. As depicted in FIG. 2, the dielectric covering 14 completely encases each conductor 12 to electrically insulate adjacent conductors.
As described in the above identified Schneck Patent, the flat conductor cable can be interconnected to printed circuit boards or other electrical flat components by mounting specially designed electrical connectors onto the flat conductor cable at selected intervals at which point the dielectric covering is removed from one side to expose the conductors for electrical connection. In the prior art Schneck structure, the bared portion of the conductor cable is a relatively wide strip to insure good electrical contact will be made between the exposed conductors and the printed circuit board at two spaced locations.
Referring now to FIGS. 1 and 3, there is shown a portion of the conductor cable 10 in which a pair of spaced strips 16 and 18 have been formed across the conductor cable in a normal relation to its length. These strips are removed by a pair of spaced abrasive wheels that are moved across the cable 10 in a direction normal to its length. After the two strips have been removed from the conductor cable 10, that portion of the cable 10 is bent into a Ushaped loop configuration and fitted into an electrical conductor 20 as will now be described.
Electrical connector 20 has an elongated hollow housing 22 having a base portion 24 and cover portion 26. The base portion 24 has a U-shaped cross section as depicted in FIG. 4, and the cover 26 fits over its upper open end. The cover portion 26 comprises a flat plate 28 having a centrally located elongated slot 30 formed lengthwise of a sufficient width to permit a circuit board 32 to be inserted therethrough. At the opposite ends of the cover portion 28 there is provided a pair of downwardly extending legs 34 spaced apart a distance slightly less than the width of side walls 36 to provide a frictional fit. Between the upper edge of side walls 36 and the lower surface of plate 28 there is provided a pair oflongitudinal slots 38 of a sufficient thickness to permit the conductor cable 10 to be inserted therethrough as shown in FIG. 4.
An elongated U-shaped cross sectional spring element 40 is contained within the housing 20 for spring biasing the exposed cable conductors against the sides of the circuit board 32. The outer ends of the arms 42 of U-shaped spring 40 underlie the longitudinal slot 30 and are in alignment therewith.
To mount the connector 20 on the cable 10, cover 26 is removed and the cable 10 is bent into a substantially U-shaped symmetrical with the pair of stripped sections 16 and 18. This loop portion is then inserted between the spring arms 42 until it substantially reaches the bottom. In this position, it is noted that the unstripped portion 44 between the pair of strip sections 16 and 18 is located at the base of the loop portion and that the faces of strip portions are in opposed relation at the curved upper portion of the arms 42 of U-shaped spring 40. Thus, when the printed circuit board 32 or the like is inserted into the connector, it will make contact with the stripped sections of the electrical conductor 10.
From the foregoing, it will be appreciated that similar connectors 20 can be mounted along the length of the conductor cable as required.
To insure good electrical contact between circuit board 32 and both exposed conductor strips 16 and 18, it has been found that the width of each strip should be in the range between one-fourth and three-eights of the total distance between the far lateral edges 48 and 50.
We claim as our invention:
1. An improved method of making a flexible flat conductor cable and mounting one or more electrical connectors on said cable at selected intervals along its length, said connectors having an elongated spring of substantially U-shaped cross section contained within an elongated housing such that the opposed faces of the arms of said U-shaped spring underlie and are aligned with an axial slot in said housing, comprising the steps of:
a. arranging a plurality of flat conductors in a spaced parallel relation,
b. encasing said flat conductors in a dielectric covering to form a flexible flat conductor cable,
0. removing across said entire cable pairs of spaced strips of said dielectric covering from one side of said cable in a direction normal to the cable's length at selected intervals along said cable's length, and
d. mounting one of said electrical connectors on said cable at said selected intervals with said cable extending sidewise through its elongated housing and with a loop disposed between the arms of its U- shaped spring, where the distance between said spaced strips and the width of each strip is selected to coincide with the opposed faces of said loop.
2. The method defined in claim 1, wherein the width of each of said strips in between one-fourth and threeeights of the total distance between the far lateral edge of said pair of strips.