On the initial stages of phase formation at the solid Cu/liquid Sn-based solder interface

The very initial stages of interfacial interactions between Cu and liquid Sn-0.7 wt%Cu alloy for dipping time t between about 50 and 65 ms are studied for the first time by ultra rapid dipping. For t < 65 ms, only the η-Cu6Sn5 phase is observed at the interface, the ε-Cu3Sn phase being absent at TEM scale. For t ∼ 1 s the classical Cu/ε-Cu3Sn/η-Cu6Sn5/liquid alloy configuration is found at the interface. A schematic illustration of phase growth at Cu/liquid Sn interface, based on these experimental results, is proposed.183