Effect of Strain-rate on the Mechanical Behavior of Pt-Films for MEMS

A method to measure the mechanical behavior of Pt thin films was developed. It employs high magnification optical microscopy and Digital Image Correlation to extract sub-micron (100 nm local displacement resolution) deformation fields in free-standing thin films and calculate their elastic/plastic properties as a function of strain rate. In this study, the specimen gauge length and thickness were 1000 μm and 400 nm, respectively, and the gauge width varied between 100 μm and 200 μm. The micron scale specimens were loaded using a custom-made piezoelectrically driven micro-tension system and the applied nominal strain rates were between 10 to 10 s. The stress-strain diagrams showed a linear elastic regime up to the yield stress, with elastic modulus E = 178.3 ≤ 6.2 GPa.