Dielectric Breakdown of Polymer Films

Strong electric fields have been applied to dielectric polymer films to study field-induced mechanical stresses. For voltages near breakdown the mechanical forces are sufficient to cause localized deformation in some polymer films. Considerable field enhancement can occur at the deformation sites, leading to reduced nominal dielectric strength for the samples. Experimental evidence for electromechanical deformation is presented as a possible explanation for the poor agreement between the observed dielectric strength and that predicted theoretically.