Nondestructive evaluation of multilayer capacitors using electromechanical resonance phenomena

Electromechanical resonances of ceramic multilayer capacitors are calculated mechanically free and clamped boundary conditions using vibration and piezoelectric equations. BaTiO₃-based and Pb(Mg _1/3Nb_2/3)O₃-based multilayer capacitors have been used to check the theoretical calculation. Frequency spectra of impedance and phase angle, capacitance, and loss tangent of the capacitors under DC bias fields were carefully measured. A sudden change around the resonant frequency is observed in these spectra. A damped resonance indicates a defective capacitor while an undamped resonance corresponds to a defect-free one. Experimental results suggest that it is possible to use the spectra as a real-time nondestructive evaluation method