Interfacial reactions at Ga-21.5In–10Sn/Cu liquid-solid interfaces under isothermal and non-isothermal conditions

The present work investigated the effect of isothermal and non-isothermal conditions on the interfacial reactions at Ga-21.5In–10Sn/Cu interfaces. Increasing the isothermal temperature from 140 to 180 °C, the growth mechanism of CuGa2 changed from mixed mechanism (reaction control and volume diffusion) to volume diffusion mechanism. At higher reaction temperature such as 220 and 260 °C, the growth behavior of interfacial CuGa2 was controlled by grain diffusion regime. When the reaction temperature increased from 140 to 310 °C, the morphology and the preferred orientation degree of CuGa2 plane was weakened while phase structure and preferred orientation of CuGa2 did not change. At the same hot end temperature, the temperature gradients induced by non-isothermal environment had no significant influence on the morphology of interfacial CuGa2. This study can provide the important information to determine the soldering process temperature for the soldering of Ga-based alloys/Cu system and will guide the design of Ga-based liquid alloys/Cu conductors for the flexible and wearable electronics.