Abstract: Disclosed is a method of fabricating a microelectronic package, especially a microelectronic package having copper circuitization on a dielectric substrate. The method includes the steps of depositing a chromium adhesion layer on the dielectric substrate, depositing a copper seed layer on the chromium adhesion layer, depositing photoresist on the copper seed layer, imaging and developing the photoresist, and forming a pattern of copper circuitization on the selected portions of the send copper layer. The chromium adhesion layer material is removed from the dielectric substrate by contacting the chromium adhesion layer with aqueous sulfuric acid electrolyte, while maintaining the chromium adhesion layer electrolytically in series with a counterelectrode, and maintaining the chromium adhesion layer anodic with respect to the counterelectrode. The chromium adhesion layer material is oxidized to soluble Cr.sup.+3, while substantially avoiding formation of Cr.sup.+6.

Abstract: A fully cured or substantially fully cured polyimide is etched by contacting the imide with an aqueous solution of a metal hydroxide such as an alkali metal or alkali earth hydroxide and a metallic compound selected from metal carbonates, sulfates and phosphates. The presence of the carbonate, sulfate or phosphare reduces the undercutting of a resist pattern on the polyimide.