Kinetic behaviour of diffusion-soldered Ni/Al/Ni interconnections

The layer growth of intermetallic phases occurring in Ni/Al/Ni interconnections formed by the process of diffusion soldering was studied. The layer thicknesses as a function of the treatment time at 720 °C and the Ni concentration profiles in the interconnection zone were measured for the stoichiometric AlNi, Ni-rich AlNi, and AlNi3 compounds. The growth rate constants were calculated, considering the incubation and transition periods preceding the steady-state growth of the intermetallic phases. The fastest growth occurs for stoichiometric AlNi and the slowest growth occurs for Ni-rich AlNi. The values of the integral interdiffusion coefficients for the stoichiometric AlNi, Ni-rich AlNi, and AlNi3 were determined. The results fall within the range of values presented in previous work dedicated to Ni/Al diffusion couples.