Scintillation Breakdowns and Reliability of Solid Tantalum Capacitors

Abstract

Scintillations are momentarily local breakdowns in tantalum capacitors, which are often considered as nuisances rather than failures. However, this paper shows that scintillations are damaging for more than 30% of part types and up to 100% for some lots. Scintillations can be observed after many hours of operation, and the probability of repeat scintillations is higher than of the initial event. In this paper, a time-dependent scintillation breakdown is considered as one of the major reasons of failures during steady-state operation of the capacitors. Using a modified thermochemical model, the distribution of times to failure can be simulated based on the distribution of breakdown voltages. The analysis of distributions of scintillation breakdown voltages and the assessment of the safety margins are critical to assure high quality and reliability of tantalum capacitors.