Digital image correlation of metal nanofilms on SU-8 for flexible electronics and MEMS

This paper presents strain measurements using digital image correlation of common microelectronic metal nanofilms deposited onto a polymer substrate (SU-8), which has applications in flexible electronics and nano/microsystems reliability analysis. The novel experimental method is based on digital image correlation coupled with microtensile test apparatus for the in situ investigation of the deformation behaviour of the deposited thin films under uniaxial tensile loading. One of the key features of the method is the real-time two-dimensional strain field measurements on a bare thin film surface, during the deformation process, without any initial speckle or grid deposition. The outstanding performances of the method, having a spatial resolution of 0.7 νm, allow one to envisage further studies related to the understanding of the mechanical behaviour of such thin films and, in particular, the damage localization process.