Young's modulus and tensile strength of CuNi(Mn) thin films on polyimide foils by tensile testing

Force-strain curves were measured for 1.0 μm and 1.5 μm thick Cu_0.57Ni_0.42Mn_0.01 films on 8 μm thick polyimide foils by tensile testing. By separating the force working on the polyimide foil from that working on the metal-polyimide compound, stress-strain curves for the CuNi(Mn) films were obtained. Young's modulus and tensile strength were determined for as-deposited and annealed [350 °C, 1 h, N₂/H₂(5 vol%) atmosphere] films by this method. Crack propagation starts at the end of the elastic region at 0.2 to 0.7% strain, depending on the film thickness and the thermal treatment. The cracking behavior is described by a steady-state approximation.