Special Reviews of Trends in Recent Printed Circuit Technology

Technical Trends of Photoresists and Resist Inks

Abstract

Focussing on the liquid photo-imageable solder mask, an outline has been given concerning the technological tendency of liquid type photoresists and resist inks for printed wiring boards. With the increasing progress of the surface mount technology, higher density and finer wirings are demanded for printed wiring boards, and a higher accuracy and a higher reliability are required for the solder masks. From these backgrounds, electrodeposition type photo-resists for forming patterns were developed, and the liquid photoimageable solder masks used already widely as a main stream of the solder masks are planned to improve further its characteristics such as resolution and electroless gold plating resistance, etc. On the other hand, the development of an ink capable of screen cleaning with an alkali solution is carried out concerning the resist ink due to strengthening the regulation for chlorine group solvents.