Thick film resistor testing by electro — Ultrasonic spectroscopy with DC electric signal

The new method of non-destructive testing of the thick film resistors is presented. There are two phenomena which lead to the resistance modulation: (i) The interaction of the charge carriers with phonons, (ii) The ultrasonic signal changes the contact area between the conducting grains in the resistor structure. Ultrasound-excited resistance change in polymer based thick film structures is about 0.005 Omega to 1 Omega, which corresponds to the relative resistance change of the order from 10
^-6
. We suppose that the resistive structures with defects are more influenced by the ultrasonic vibrations. The intermodulation signal can be used as the quality and reliability indicator.