Robert Boschgmbh

Fedor Modic

Herbert Zimmermann

Kurt Spitzenberger

Wolfgang Leibfried

Manfred Nitsch

Gunter Kruger

Klaus Kuttner

Very fine solder-coated conduction paths are made on ceramic, glass or enamel substrates by the combination of a first step in thick-film technology followed by the photo-masking and etching steps typical of thin-film technology, after which galvanic reinforcement of the initial calcined copper paste layer is performed in the locations where the initial layer is exposed by the developed mask. A lead-tin solder layer is then galvanically deposited, which is thicker than the mask, after which the mask is removed and the newly exposed portions of the initial copper layer are etched away. A reflow treatment of the solder layer pattern consolidates the solder layer by melting on top of the boundaries of the unetched initial copper layer. It is possible to obtain conduction path spacings down to 50 .mu.m with conduction paths coated with solder that have excellent adhesion to ceramic, glass or enamel substrates.

Process of producing galvanic layers of solder of precise contour on

After a valve metal layer on an insulating substrate has been metallized by sputtering on two layers of copper separated by an intermediate layer of iron, nickel or cobalt, and the combined circuit and component pattern has been etched out, followed by selectively etching away the metallization over the resistance components of the circuit, electroless deposited nickel and gold layers are successively applied to the remaining metallization and a solder layer is then applied on top by contact with liquid solder.

Electronic thin film circuit unit and method of making the same

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Stuttgart, Germany

Fedor Modic