Corrosion Kinetics Investigation on Cu-Al Alloy in Sulfate Environment under Various Temperature and pH Values

Corrosion is one of the major reliability concerns affecting the reliability of the Cu-Al wirebond system. The corrosion of intermetallic compound (IMC) has been shown to initiate at the Cu-Al wire bond ball bond-pad interface. Propagation of the interface crack would cause the failure of the semiconductor electronics devices. Methods are needed to quantify the corrosion propensity of the intermetallics under a range of operating conditions. The Cu-Al wirebond system may be exposed to sulfates present in the electronic mold compounds or from the residue of plating baths. In this paper, the specific intermetallics encountered at the Cu-Al wirebond interface have been formulated. The corrosion propensity has been measured under a range of impurity concentrations, temperatures, and pH values. The corrosion rate of the intermetallics has been quantified through the measurement of polarization curves, anodic and cathodic Tafel slopes, open circuit corrosion current density, and open circuit potential.