Non-Contact Evaluation of Film Electroadhesion using Laser Ultrasonics and SAWs
Film adhesion is a critical phenomenon that has been thoroughly investigated to improve structural reliability, notably in microelectronics. In this work, Laser Ultrasonics is used to evaluate the bond quality achieved by an original electroadhesion process. More precisely, an electrostatic field is applied to a polyvinyl chloride film deposited on an aluminum substrate, thereby eliminating the need for an adhesive layer. The effects of electroadhesion on Surface Acoustic Waves (SAWs) are explored, with results solely attributable to interfacial adhesion changes. These waves are generated in thermoelastic regime by a frequency-doubled Nd:YAG pulsed laser and detected by a Mach-Zehnder heterodyne interferometer. The experimental Rayleigh mode dispersion curves are compared to the theoretical ones, facilitating adhesion evaluation through inverse problems. Furthermore, Finite Element Modeling predicts acoustic wave propagation in the structure, enabling experimental and numerical comparisons. This research paves the way for a multiphysical analysis of electrostatic field-induced coating adhesion.