Silicone-coated polyimide films deposited by surface dielectric barrier discharges

Hybrid dielectric barrier discharges are investigated for plasma generated on the surface of a dielectric layer, where two conducting electrodes of high voltage and ground are formulated on the upper and bottom surfaces. Using a flexible thin polyimide-film of a thickness ranging from 25 to 125 mu m, a plasma is generated with a voltage of about 1 kV and a frequency of 40 kHz. However, the surface of the dielectric layer was etched through a chemical reaction involving plasma oxygen radical species, and thus the polyimide films failed readily, resulting in dielectric breakdown within short operating time ranging from a few minutes to several tens of minutes, based on the film thicknesses of 25 mu m and 125 mu m, respectively. These plasma erosions were prevented by coating the polyimide surface with a 25 mu m thick silicone paste. The silicone-coated film surface was then reinforced remarkably against plasma erosion as the organic polymer was vulnerable to chemical reaction of the plasma species, while the inorganic silicone exhibited a high chemical resistance against plasma erosion.