Wetting interaction between Pb-free Sn-Zn series solders and Cu, Ag substrates

This study investigated the wetting behavior of Cu and Ag with pure Sn and several Sn-Zn solders, including Sn-9Zn (abbreviated as Sn-Zn), Sn-8.55Zn-0.5Al (abbreviated as Sn-Al), and Sn-8.55Zn-0.5Ag-0.1Al-0.5Ga (abbreviated as Sn-Zn-Ag-Al-Ga). Results show that Sn-Zn solders exhibit better wettability with both Cu and Ag than pure Sn. The primary interfacial intermetallics in Sn-Zn are (Ag,Cu)Zn rather than (Ag,Cu)Sn. By way of alloying modification, the Sn-Zn-Ag-Al-Ga alloy exhibits a greater wetting behavior than other solders.