High-strength and high-conductivity nanotwinned Cu lightly doped with Ni

We utilized a Cu–Ni co-electrodeposition method to enhance the mechanical strength of nanotwinned copper (NT-Cu), achieving an ultimate tensile strength (UTS) of over 866 ± 20.1 MPa, a 13.1% increase from the original NT-Cu (UTS max of 766 ± 2.7 MPa). ICP-MS analysis showed a nickel content of 0.467 ppm. The Cu–Ni alloy also demonstrated an international annealed copper standard (IACS) value of over 81%, outperforming cold-rolled Cu foils in terms of mechanical strength and IACS value. The addition of Ni was to reduce the Cu grain size, and to increase the twin density of the NT-Cu. A modified confined layer slip (CLS) model is proposed to account for the refined microstructure of the NT-Cu-Ni alloys. Therefore, this approach can tailor the microstructure of NT-Cu, increase its strength, and maintain high electrical conductivity, making it a promising option for advanced packaging materials.