Formation and growth of Cu–Al IMCs and their effect on electrical property of electroplated Cu/Al laminar composites

Abstract

Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet. During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion and reaction and its kinetics and also the electrical resistivity of the composites were studied. The results show that no Cu–Al IMC layer is observable as the composites are annealed at 473 K for time till 360 h, indicating that the Zn intermediate layer can effectively suppress the Cu/Al interfacial diffusion. However, as the composites are annealed at 573 K and above, Zn atoms in the Zn layer dissolve into the Cu layer. Tri-layered reaction product of CuAl2/CuAl/Cu9Al4 then forms from the Al side to the Cu side. The IMC layer follows the diffusion-controlled growth kinetics. Electrical resistivity of the Cu/Al composites increases with the increase of the annealing temperature and time.