Electrodeposition of Photoresist for Printed Writing Board Application – An Answer to Lower cost and Fine Line Requirements

Spring/Summer 1995

H. Schwab, CIBA-GEIGY Limited

The electro-deposition ( ED) of organic coatings is over 30 years old. Development initiated during the 1960s, brought this technology into practical applica­tions. Now ED is a state-of-the-art coating process which finds use in various industries. ED is used to apply protective coatings to car bodies, with substantially better results than previous methods. In other industries, cost savings are achieved through improved uniformity of the surface coating. A more recent refinement of this technology is used to apply photoresist for the manufacture of PWB. This development was introduced during the 1980’s and resulted in the practical use of electrophoretic depositable photoresists as materials used for image transfer in the Printed Wiring Boards (PWB) industry. In the following paper, the various aspects of the available systems will be described; and questions will be answered relating to process integration, advantages over existing photoresist technologies, environmental compatibility, and costs.