Phase growth competition in solid/liquid reactions between copper or Cu3Sn compound and liquid tin-based solder

Interfacial reaction between solid ɛ-Cu3Sn compound and liquid Sn at 250 °C is studied for the first time. The reaction product formed at the ɛ-Cu3Sn/liquid Sn interface consists of the single η-Cu6Sn5 phase. The growth kinetics of the η phase formed at the incremental ɛ/liquid Sn couple (ɛ/η/Sn configuration) is compared to that of η phase formed at the classical Cu/liquid Sn couple (Cu/ɛ/η/Sn configuration). The experimental method consists first in processing of intimate interfaces by dipping peaces of solid ɛ-Cu3Sn compound and Cu in liquid Sn for 1 s at 250 °C. Afterwards, isothermal holding of such pre-performed couples for 10, 30, 120 and 480 min at 250 °C are performed for both couples. A theoretical analysis of the growth kinetics of η phase and comparison of its growth in both configurations are performed.