Preh Elektrofeinmechanische Werke Jakob Preh Nachf Gmbh & Co.

Gisela Westermeir

Peter Ambros

Walter Budig

Heinz-Jurgen Siede

Friedhard Fehr

Rudolf Limpert

Hans-Peter Koch

The present invention describes an improved reverse lamination process for reparing printed circuits with resistors, conductor strips and/or contacts integrated in the circuit. A separating layer is applied on a metallic intermediate carrier. The intermediate carrier thus coated is then printed with a conductive paste in a desired. mirror-inverted layout to provide the resistors, conductor strips and/or contacts. This is followed by the lamination which is carried out under temperature effect and under pressure, the thus laminated package comprising the intermediate carrier, an intermediate layer and the final substrate. The intermediate carrier is subsequently removed, and the separating layer is etched off. The separating layer acts as a parting agent to permit easy mechanical separation and reuse of the metallic intermediate carrier.

Process for preparing printed circuits

An x-y position detector is shown which comprises a pen and contact plate with a resistive layer formed thereon. Point electrodes are provided on the four sides of the resistive layer. The materials of the resistive layer and the pen are selected such that the pen is in reliable galvanic contact with the resistive layer. The resistive layer is hard and smooth, and permits easy motion of the pen. The resistive layer consists of carrier particles with a hardness of between 5 and 9 on the Mohs hardness scale, pyrolytically coated with carbon and embedded in a binder whereby the resistive layer is hard and enables easy motion of the pen. The surface on which the pen moves is formed by molding the resistive material on a smooth intermediate substrate.

X-Y Position detector

A thick-film capacitor and a printed circuit are described, this capacitor being designed for implementation by printed-circuit technology, while the printed circuit contains capacitors of this type, together with the associated conducting paths. The capacitor dielectric comprises a screen-printable dispersion of dielectric filler substances in a polymeric material which can be cured at comparatively low temperatures, especially a polymeric resin from the group comprising polyurethane resins, polyester resins, epoxy resins and melamine formaldehyde resins. The use of a dielectric of this type enables lower curing temperatures to be used, in the region of approximately 200.degree. C., in contrast to conventional designs of thick-film capacitors with a dielectric containing a glass or ceramic frit, which require firing temperatures of the order of 1,000.degree. C. The production of the lower and upper electrodes of the capacitors is preferably carried out in combination with the production of the associated conducting paths of the printed circuit. The electrodes of the capacitors and the conducting paths associated therewith, are preferably obtained by a deposition process, from a chemical bath, this process involving no electric current. Deposition is carried out onto an activated base layer producing completely solderable electrodes and conducting paths, of copper or nickel, which adhere strongly to the substrate layers. A description is also given of a printed circuit, of the above type, with capacitors arranged in a matrix, and with associated connecting leads, this printed circuit being designed as a capacitive input keyboard for data-processing systems.

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Hohenroth, Germany

Gisela Westermeir