Process for producing electrical circuits with precision surface features

摘要

A process for producing fine pitch surface features on a multilayer printed circuit boards such as copper-polyimide interconnects without requiring a thick copper plating foil. Initially, a thin first conductor (less than 1 micron) is vacuum deposited on a dielectric base and the dielectric base is disposed on a substrate. The substrate is then laminated and through-holes are formed therethrough. A plating seed is deposited in the through-holes and resist is patterned on the first conductor. A second conductor is deposited on the exposed portions of the first conductor and on the sidewalls, the resist is stripped and the portions or the first conductor beneath the resist are removed using a brief wet chemical etch to form spaced features without significant undercut. In the preferred embodiment, vacuum deposition occurs in a continuous roll sputtering system.