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 spec imen 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 mod ulus lower than literature values for bulk polycrystalline values, but had high values of the yield and ultimate strengths. Closed-loop feed back control of the piezoelectric actuators allowed load-controlled fa tigue tests with a cycle duration of 15 s. Stress-endurance results fo r this set of copper films is reported and compared to previous result s. Published by Elsevier Science Ltd.