Some Observations on the Accelerated Ageing of Thick-Film Resistors

[摘要] Methods of accelerating the ageing of thick-film resistors (TFRs) have been explored, with encouraging results fromexperiments in which elevated temperature and damp heat were inflicted on TFRs. Consistent acceleration wasobtained by increasing temperature, whether by storage or dissipation, the activation energies for thermal ageing ofvarious resistor families lying in the range 0.5 eV–1.5 eV. Acceleration by humidity (RH) was also obtained,corresponding, for example, to a halving of life for a 20% increase ofRH, some resistance changes being about anorder of magnitude larger than those obtained at elevated temperature. The encapsulations played a dominant rolein the degradation of resistors under both stress conditions.According to the theories of conduction, degradation could occur because of reactions at conductive sites,causing corresponding changes in the conductivity and resistance versus temperature (R(T)) characteristics.Progressive degradation certainly did occur, as evidenced by the conformity of the ageing behaviour to a diffusion-type(time)1/2dependence accompanied by shifts in theR(T) characteristics. Some interpretation of thedegradation has been possible by referring to an empirical model of the temperature dependence of resistance, butconflicting changes can be reconciled with the model only by postulating competing degradation mechanisms. Thereport covers an early stage of the work.

[学科分类] 工程和技术（综合）