The effect of corrosion in acidic solution to the phase and microstructure of SAC305 solder

Abstract

The effect of corrosion to the phase and microstructure of solder Sn-3.0Ag-0.5Cu (SAC305) in 1.0 M HCl were investigated under polarized condition. The potentiodynamic polarization analysis was fixed at a scan rate of 2.5 mV.s-1. The initial scan potential range was fixed from -2 to +2 V and scanned part by part accordingly from the polarization result. The samples were characterized by using scanning electron microscope (SEM), X-ray diffraction (XRD) and potentiodynamic polarization. Finally, the polarized solder will be sent to another phase and microstructure analysis. Evolutions and changes experienced by the solder due to polarization are discussed. SEM and XRD results confirmed that before the solder polarized, there are three phase that appeared at the surface that is β-Sn, Ag3Sn and Cu6Sn5. After polarized, a passivation layer consisting of SnO and SnO2 presented to increase protection of SAC305 solder against further corrosion attack. It was found that Sn is the major phase that dissolved during polarization, proven from the XRD analysis after polarization. This reveals that the dissolution process of Sn significantly control the corrosion performance of SAC305 solder in HCI solution.