Selective electroetch of copper and other metals

摘要

The present invention relates to a method for selectively electroetching a metal from an electrical device having the steps of: immersing the electrical device in an etching solution; immersing a cathode in the etching solution; applying an etching potential to a preselected area of the metal; and maintaining a passivation potential at the metal to remain unetched. The metal to remain unetched is not electrically connected to the preselected area and the passivation potential does not equal the etching potential. The present invention further relates to a method of forming an electrical connection to the inner layers of a multilayer circuit board having a copper foil surface layer and copper containing inner layers.