Tension-tension fatigue of copper thin films

Tension-tension, load-controlled fatigue results extending to over 100 000 cycles for electron-beam-evaporated copper are reported. The specimen is fabricated as a single tensile coupon with hundreds of grains across the width but only one or few through the thickness, supported on a silicon frame. These specimens had measured values of Young's modulus lower than literature values for bulk polycrystalline values, but had high values of the yield and ultimate strengths. Closed-loop feedback control of the piezoelectric actuators allowed load-controlled fatigue tests with a cycle duration of 15 s. Stress-endurance results for this set of copper films is reported and compared to previous results.