Two types of mechanical tests associated with acoustic microscopy characterizations were performed to investigate the mechanical stability of PSG and Si3N4 passivation films. An in situ tensile test micro-device was installed under a scanning acoustic microscope to study the damage development in the passivation films deposited on A1,1%Si substrates. The analysis of the attenuation of the acoustic signature of the film/substrate systems and the variations of the leaky surface acoustic wave velocity permitted detection of the cracking and decohesion of the passivation films. The four-point bending test was used to submit passivated aluminum multilayers deposited on silicon substrates to cyclic compression. Then subsurface acoustic images revealed decohered zones in the passivation.