Electrochemical Evaluation of Copper Etchant to Minimize Galvanic Etching

Abstract

In the PCB industry, Cu is the most commonly used metal for circuit line and pad materials. After the wiring process, soft etching is performed to remove the copper oxide layer formed on the circuit or pad. When Au is applied to lower some contact resistance, Cu is excessively etched by a galvanic coupling of Au and Cu. In this study, electrochemical evaluation such as open circuit voltage (OCV) and polarization curve in two different solutions were analyzed since the over etching phenomenon was observed only in the case of Au and Cu galvanic coupling. Finally, the etching conditions in which over etching did not occur even in the galvanic couple of Au and Cu were confirmed.