A unified expression for enlargement law on electric breakdown strength of polymers under short pulses: mechanism and review

A unified expression for the enlargement law including the volume, the area, and the thickness effects on electric breakdown strength (EBD) of polymers under short pulses is presented based on the electron impact ionization criterion and the two-parameter Weibull statistical distribution. It is concluded that EBD is related to the total amount of the discontinuous structures (Amt) in a dielectric and that logEBD is linearly dependent on logAmt with a slope rate of -1/β, where β is the shape parameter of the two-parameter Weibull distribution. Three deductions have been obtained for the enlargement law based on this conclusion, respectively, that is, EBD and the dielectric volume (or the thickness or the cross-section) conforms to a minus power law with a power exponent of -1/β. Different sets of experimental data are reviewed and re-analyzed to give a support for each deduction.