Corrosion Investigation of Sn-0.7Cu Pb-Free Solder in Open-Circuit and Polarized Conditions

Abstract

Abstract The corrosion performance of Sn-0.7Cu solder alloy was investigated in 1 M hydrochloride acid by means of open-circuit potential and potentiodynamic polarization techniques. In open-circuit potential measurement, the potential showed almost constant reading after achieving potential -550 mV, consistent with single dissolution peak observed in potentiodynamic polarization. This revealed single element dissolution process of Sn took place. Supporting morphological and phase analyses were done by using scanning electron microscope and X-ray diffraction. Phase analysis confirmed the corrosion product are SnO and SnO2. Morphological analysis showed two type of oxide layer formed as corrosion product, which are compact oxide layer and loose rod-like oxide layer after polarization, while rod-like corrosion product was diminished in open-circuit condition. This indicate that complete protection from further corrosion was impossible due to the incomplete passivation layer formation in potentiodynamic polarization.