NDE of multilayer ceramic chip capacitors based on acoustic waveguides excitation

An acoustic waveguide technique is investigated as a potential tool for detecting delaminations, voids, or microcracks in multilayer ceramic chip capacitors. The technique uses acoustic transducers mounted on tapered buffer rods to excite and to detect acoustic waves in a capacitor. The points of the transmitting and receiving buffer rods are brought in contact with the opposite ends of the capacitors, and a pulse excitation is applied. For a defect-free sample, the received acoustic signal is a series of echoes representing reverberations within the capacitor. The presence of defects in the capacitor changes the acoustic propagation properties, resulting in changes in the measured echo train. A series of experiments was performed for a number of capacitors to verify the potential of acoustic waveguide coupling