Firma Carl Freudenberg

Gunter Trogisch

Horst Kober

A multi-layer through-hole contacted flexible circuit board and method of manufacture thereof is presented having a laminar construction which is strictly symmetrical in the bending area; and which have no exposed adhesive. Registration holes are first introduced in a copper-laminated base material, then, avoiding the bending area, with the aid of the registration holes, an adhesive layer is applied to the non-conductive film carrier of the base material. Next, a second copper foil is placed on the adhesive layer. Thereafter, all of the layers are laminated. This is followed by the formation of through-holes in the area surrounding the bending area while circuit patterns are formed in the flexible or bending area (the registration holes again providing assistance in positioning). The spaces between the circuit pattern, as well as the entire copper foil, is then etched away in the bending area, and, finally, all the conducting path areas are covered with non-conductive cover film. As a result, the conducting paths are located in the 'neutral section', that is, the area of the flexible circuit board which is neutral with respect to the forces generated during bending.

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Seeheim-Jugenheim, Germany

Gunter Trogisch