Thick-film capacitor manufactured by printed-circuit techniques

Abstract

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.