Method of making flat cable

DETAILED DESCRIPTION A principal object of this invention is to provide a flat electrical cable comprising an upper insulator layer, a lower insulator layer connected to the upper layer, a lower insulator layer connected to the upper layer along continuous parallel spaced-apart seams and an intermediate layer comprised of individual strands of conductors which lie adjacent and parallel to the seams and the conductors do not have an adhesive residue thereon.
The upper layer may include a plurality of raised surfaces running parallel to each other along the length of the flat cable.
The lower layer may be substantially planar and include a pattern formed on the majority of the surface of the lower layer.
The upper and lower insulator layers may be polyester.
The conductors may be copper.
The seams may be ultrasonically welded.
The conductors may be exposed at an end portion of the flat cable beyond the upper and lower insulator layers.
The cable may include a continuous seam except for a nonbonded area where the upper and lower insulator layers are not connected.
The cable may include a continuous seam except for a nonbonded area where the upper and lower insulator layers include windows that expose the conductors.
In another embodiment of the invention, a flat electrical cable is provided comprising an upper layer of polyester having a ribbed surface, a lower layer of polyester connected to the upper layer along continuous parallel spaced-apart ultrasonically bonded seams and individual strands of copper conductors lying substantially parallel and adjacent to the seams between the upper and lower layers.
The lower layer may have a pattern along the majority of its exposed surface.
In another embodiment of the invention, a clockspring is provided for electrically connecting an airbag in a steering wheel of a vehicle through a steering column to crash sensors, the clockspring comprising a housing having an inner chamber and a flat electrical cable including an upper insulator layer, a lower insulator layer connected to the upper layer along continuous parallel spaced-apart seams and an intermediate layer comprised of individual strands of conductors which lie adjacent and parallel to the seams and the conductors do not have an adhesive residue thereon, the flat electrical cable being mounted in the chamber of the clockspring