Effect of cold rolling on microstructure and mechanical properties of a Cu–Zn–Sn–Ni–Co–Si alloy for interconnecting devices

Abstract A Cu–Zn–Sn–Ni–Co–Si alloy has been developed to meet the requirements of high thermal stability and good processing properties for interconnecting devices. The effects of cold rolling on the microstructure and mechanical properties are investigated. The tensile properties, thermal stability, and microstructure are characterized, complemented by electron back-scatter diffraction analysis and transmission electron microscopy. The precipitated phase of the orthorhombic (Ni, Co)2Si has been found in the rolled alloy, which is incoherent to the Cu matrix. With the increasing rolling strain, the alloy exhibits higher tensile strength and thermal stability while the electrical conductivity and strain rate sensitivity remain constant. The increasing rolling strain has a combined effect on the matrix and precipitates, leading to higher densities of dislocation and twin as well as more and finer precipitates. After cold rolling to 50% stain, the tensile strength, electrical conductivity and softening temperature of the Cu–Zn–Sn–Ni–Co–Si alloy are 650 MPa, and 33% IACS, and 325 °C, respectively.