Impact of circuit resistance on the breakdown voltage of tantalum chip capacitors

Experiments are described in this paper whose results suggest a clear mathematical relationship between total circuit resistance (including the capacitor’s ESR) and the voltage at which a capacitor is likely to break down. Specifically, the relationship defines how much each capacitor’s (not precisely known) breakdown voltage is affected by changes in circuit resistance. Since a factor that strongly influences the reliability of a tantalum capacitor is the ratio of the capacitor’s breakdown voltage to the applied voltage, if the impact of circuit resistance on breakdown voltage can be established, then, at least indirectly, the impact of circuit resistance on reliability can be inferred. The breakdown voltages of individual capacitors, drawn from large randomized samples, were determined for different values of circuit resistance. These data were analyzed and found to fit a specific mathematical relationship with a high degree of confidence. The relationship was found to hold for different batches and part-types. The test methods employed to minimize statistical noise are described in the paper as is the resulting mathematical relationship. Implications of the relationship are explored and avenues of future research are suggested.