Patent ID: 7635524

Claim:
A method of preparation for a dielectric insulating film comprising the steps of: a) dissolving an organosiloxane polymer in an organic solvent; b) regulating the content of second metal ions to be 0.5 ppm or lower where the second metal ions are at least one selected from the group consisting of Na, K, Ca, Fe, Cu, Ni, Mg, and Zn; c) regulating the content of first metal ions to be 1 to 200 ppm based on the weight of a coating composition, where the first metal ions are at least one selected from the group consisting of Rb ions, Cs ions, and a mixture thereof to obtain a coating composition; and d) manufacturing the dielectric insulating film from the coating composition, wherein regulating the content of the second metal ions comprises removing the second metal ions by washing with water, or by using an ion exchange resin filter or a zeta-potential filter.