Process of producing galvanic layers of solder of precise contour on inorganic substrates

US4640739A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Fedor Modic · Leonberg, DE
• Wolfgang Leibfried
• Manfred Nitsch · Schwieberdingen, DE
• Kurt Spitzenberger · Laichingen, DE
• Herbert Zimmermann · Freiberg am Neckar, DE

Key dates

• Filing date: Aug 15, 1985
• Grant date: Feb 3, 1987
• Expiry date: Aug 15, 2005

Classification

• Technology area (CPC H): Electricity
• CPC primary: H05K2203/0723
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

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.