Influence of Cold Rolling and Annealing on Residual Stress and Mechanical Properties of Rolled Copper Foil

A 150 μm-thick copper foil base metal was rolled by reversible cold rolling for four passes. The rolled copper foil with thickness of 35 μm was obtained, and was annealed at 180 °C for 1 h. The effects of cold rolling and annealing on the microstructure, surface residual stress, and mechanical properties of the rolled copper foil was studied. The results show that after cold rolling, the grain size of the copper foil was significantly refined, the average grain size was reduced to 5.7 μm, and the texture changed from annealing texture to deformation texture. After annealing, the average grain size increased to 9.4 μm and the texture was reverted to the annealing texture. After cold rolling, the surface residual stress of the copper foil increased sharply to 543.02 MPa, the hardness increased, the average flexural fatigue life was extended, the tensile strength along rolling direction (RD) was improved, and the elongation after fracture and the surface roughness of TD (transverse direction) face decreased. After annealing, the surface residual stress of the copper foil was recovered to 237.47 MPa, the hardness was reduced, the TD surface roughness slightly increased, the tensile strength decreased and elongation after fracture were slighthy improved, and the average flexural fatigue life was further extended.