Impact of temperature on the corrosion of lead-free solder alloy during salt spray test

Abstract

This paper presents the impact of temperature on the corrosion behaviour of lead-free solder alloy during neutral salt spray (NSS) test. The focus is made on the Sn-Ag-Cu (SAC305) solder alloy Ball Grid Array components. Components were aged during 24, 48, 72, and 96 h in a salt spray chamber Ascott at 35 °C with 5% sodium chloride (NaCl) solution at temperatures ranging from 25 °C to 45 °C to investigate the effect of temperature on the corrosion. Two observables corrosion criteria were defined for this analysis. Solder balls deterioration is visible after 72, 48, and 24 h, respectively, at 25 °C, 35 °C, and 45 °C. This shows that the temperature has a significant effect on the corrosion behaviour of lead-free solder balls. An increase in temperature from 25 °C to 35 °C and 45 °C led to an earlier onset of corrosion. Tin (Sn), oxygen (O), and chloride ion (Cl) are found on solder balls. Finally, thermal “Arrhenius Law” is used to estimate an acceleration factor (AF) and an indicative value of the activation energy (Ea) after 96 h of exposure. The kinetic of the corrosion failure mechanisms is being investigated in order to predict lead-free solder balls lifetime.