Dielectric breakdown at sub-critical fields

We present a quantitative physical model based on experimentally determined parameter values for the description of the way that dielectric breakdown occurs after a period of stressing at fields below the critical values required for deterministic theories. It is found that for most of the material lifetime isolated regions of deterioration occur and that breakdown only ensues when the field in one such region reaches a critical value that produces a runaway extension. Only at low fields, do the deteriorated regions link up to form a conducting short-circuit. The generic form used means that the theory can be adapted for different physical mechanisms, and its concepts can be applied to the electrical reliability of many different types of dielectrics in a wide range of applications.