Growth kinetics of the intermetallic phase in diffusion-soldered (Cu-5 at.%Ni)/Sn/(Cu-5 at.%Ni) interconnections

A stereological analysis was carried out in order to obtain the kinetics parameters of the (Cu1-xNix)6Sn5 growth in the diffusion soldered (Cu–5 at.%Ni)/Sn/(Cu–5 at.%Ni) interconnections where previously anomalous fast growth of this phase was described. The n-parameter in the equation x = ktn was found to be 0.27–0.15 in the temperature range 240–260 °C, respectively. This is far away from the volume control process (n = 1 if total surface of forming phase is the reference). The TEM/EDX microanalysis made across the (Cu1-xNix)6Sn5/Sn – solder showed sudden change of Sn and Cu content typical for the grain boundary diffusion as the rate controlling mechanism