MECHANICAL BEHAVIOR OF COPPER THIN FILMS SUBJECTED TO VARIOUS STRAIN RATE LOADINGS

In this study, a micro-force tensile testing machine (MTS Tytron 250) was applied to test the polyimide samples coated with different thicknesses of copper (500-1500 nm). The experiments using different strain rates (1.6 x 10(-4) to 1.6 x 10(-2) s(-1)) were conducted to the test vehicles. The results showed that the stress and strain of Cu films were strongly correlated with the strain rate and film thickness. The mechanical strength, yield stress, Young's modulus, and maximum tensile stress, increase as the strain rate increases or the thickness decreases. Strain rate sensitivity rapidly increases as the thickness decreases from 750 to 500 nm to imply that the workhardening rate increases while the thickness decreases, resulting in a higher probability of brittle failure.