Effect of Ag3Sn intermetallic compounds on corrosion of Sn-3.0Ag-0.5Cu solder under high-temperature and high-humidity condition

The aim of this study is to evaluate the effects of Ag3Sn intermetallic compounds (IMCs) on corrosion of Sn-3.0Ag-0.5Cu (SAC305) solder alloy under high-temperature and high-humidity condition. The Ag3Sn IMCs of SAC305 with various size and morphology were obtained by changing cooling rate. Commercial SAC305 solder with smallest Ag3Sn IMCs exhibits better corrosion resistance than air-cooled and furnace-cooled SAC305 solders because microgalvanic corrosion between large cathodic Ag3Sn IMCs plates and anodic Sn matrix decreased the corrosion resistance of air-cooled and furnace-cooled SAC305 solders.

► The corrosion of solder under humidity due to the microgalvanic corrosion.
► Commercial SAC305 with smaller size of Ag3Sn exhibits better corrosion resistance.
► It was postulated the occurrence of reaction between Sn and O2, Ag3Sn and O2.