Dynamic adhesion test to measure thin film interface fracture toughness

A novel experimental technique is developed to measure thin film interface toughness using laser-induced stress waves. Controlled crack initiation is attained by selectively debonding a weak adhesion region beneath the film. The inertial forces acting on the debonded portion of the film lead to stable propagation of the delamination along the film/substrate interface. A simple energy balance is used to extract the critical energy for interfacial failure, a quantity that is difficult and sometimes impossible to characterize by more conventional methods for many thin film/substrate combinations. A more complete description of the dynamic interfacial crack propagation is obtained by monitoring the crack tip location during the delamination event.