Novel methods for increasing breakdown voltages in film capacitors

Breakdown voltage of wound, polymer-film/metal-foil capacitors have been dramatically increased by briefly exposing them (after they had been spirally wound) to a low-pressure, low-temperature gas plasma. Exposure of wound polycarbonate-based capacitors to a 96%CF₄/4%O₂ gas plasma for 4 min, for example, produced a 200% increase in breakdown voltage, while exposure of similarly constructed polyester-and polypropylene-based capacitors to the same gas plasma showed more modest 23% and 4% improvements, respectively, in breakdown voltages