Wet chemical mfr. of electronic circuit networks - using photolacquer and electroless plating to obtain resistors of different values

摘要

The circuits have through holes used as contacts, and integrated resistors with different surface resistivity (SR) or different temp. coeffts. of resistance (TCR). An insulating substrate is drilled to provide the holes; coated with a photolacquer negative for all conductors and resistors; sensitised; adn electroless plated with an alloy (a) of higher SR and specific TCR. The photolacquer is removed, and another lacquer (b) used to cover some resistors (a), followed by the deposition of other alloy resistor layers nc) with lower SR and the same or different TCR. Resistors (c) are then covered with lacquer (d); and electroless- or electro- plating is used to deposit a good conducting metal (e) for conductor paths. The thin layer (a) pref. has a sharp edge after removal of the first photolacquer with a usual solvent, e.g. acetone. Method avoids etching processes which involve metal recovery and pollute drain water.