Failure analysis of RuO2 thick film chip resistors

This work presents the results of Failure Analysis carried out on RuO2 Thick Film Chip Resistors in field failed. Microscopical investigation performed on virgin, degraded and open circuit devices showed the failure mechanism involved: evidence for mechanical cracks may be related with the observed degradation and failures. On the failed and degraded devices some bad adhesion of the resistive film on the metallized alumina has been observed, which also could be consistent with thermomechanical hypothesis for the failure mechanism.