Mixed Three-Parameter Weibull Breakdown Distribution Model and Breakdown Mechanism of Metalized Films

The breakdown characteristics of the metallized film significantly affect the reliability of self-healing capacitors. Traditional two-parameter Weibull distribution can be well described breakdown distribution of metallized film, but it is difficult to describe its early failure intuitively. Metallized film breakdown under low field strength has important influence on the reliability of the capacitor. In this paper, a mixed three-parameter Weibull distribution model is established to describe the breakdown characteristics and to analyze the mechanisms of metallized film. Metallized polypropylene films with different electrode thicknesses are chosen as the object to study the breakdown characteristics and mechanisms. The paper has shown there are three apparent breakdown peaks in the breakdown field strength of 400–500, 500–600 and 600–700 V/μm, which correspond early failure breakdown, low-field defects breakdown, near-intrinsic breakdown. The metallized film with electrode thickness d1 has been used as an example to state that three-parameter Weibull model can well describe different breakdown mechanisms. Moreover, the paper has shown that near-intrinsic breakdown is the main breakdown mechanism for metallized films.