Low-Frequency Noise and Third Harmonic Testing of Thick-Film Resistors as Reliability Indicators

摘要

The noise spectroscopy measurement and third harmonic testing of thick-film layers is proposed as a diagnostic tool for the prediction of possible types of failure. The sources of fluctuations are both in the resistor volume and in contact region. From the noise spectral density dependence on the applied voltage and the sample length, and from the determination of the burst noise, we found that the contact noise spectral density can be in first approximation neglected with respect to the volume one. There are two sources of noise and non-linearity in the resistor volume: the junctions between the metallic grains and glass layers and defects of the thick conducting layer structure. 1/f noise in low frequency range is given by two components: fundamental l/f_o noise, and excess l/f_d noise created by defects. Carrier transport in thick conducting layers is not strictly linear and third harmonic voltage is proportional to the third power of electric field intensity or current density. It was experimentally proved, that the noise spectral density is inversely proportional to the square of sample length, or electric field intensity. This is a second case, where an electric filed intensity can be considered as a signal source. Noise and non-linearity quality and reliability indicators screened samples, which are anomalous. The research is aimed to identify this anomalies related to irreversible processes of sample degradation. We shall try to give additional information to select the proper transport mechanism.