Corrosion-induced degradation and its mechanism study of Cu–Al interface for Cu-wire bonding under HAST conditions

Abstract

This study explores the Cu wire corrosion-related issues and provides solutions for evaluation & analysis as the Automotive Electronics Council (AEC) continually formulates industry specification and qualification procedures for evolving Cu wire-bonding technology. Evaluation of molding resin attributes concerning about the preferential Intermetallic Compounds (IMCs) corrosion and formation of oxidation layer in the Cu–Al interface during accelerated reliability stress test (bias HAST) is discussed. Failure mechanism for Cu–Al system is microgalvanic corrosion accompanied with crevice/pitting corrosion-induced deterioration in the presence of moisture and ion impurity from resin encapsulatants. Failure analysis techniques conduct on corrosion-induced broken stitch bond issue are proposed and root cause is identified. Electrochemical studies of Au, Cu, Pd-doped Cu (PCC) and Ag alloy wire presents here for further understanding the corrosion behavior in wire-bonding packages. Potentiodynamic polarization is used to investigate the electrolyte property and corrosion performance of these specimen in the corrosive medium. The results provide vital information on the Cu corrosion study not only in ball bonds but also in stitch bonds which are of practical value to the current industry under “design for reliability” (DfR) approach to product development.