Failure Characteristics of Thin Film Capacitors

Failure characteristics of thin film capacitors are described in terms of lognormal statistics and acceleration factors are calculated from step stress and static stress testing over a limited range of stress levels. When extrapolations are made to use stress conditions, estimates of the failure probability are obtained. The range of stress conditions producing failures in a reasonable time interval is not adequate to determine whether linear or log-voltage-stress is appropriate for extrapolation. One case yields pessimistically high failure rates and might be rationalized by an extension of the commonly accepted anodization mechanism. This model assumes linear-voltage-stress to failure is linear with log-time to failure.