This invention pertains to a method of forming a coating on an electronic substrate and to the electronic substrates coated thereby. The method comprises applying on the electronic substrate a coating composition comprising an aqueous alkanol dispersion of colloidal silica and partial condensate of RSi(OH).sub.3 where R is selected from the group consisting of an alkyl radical having from 1 to 3 carbon atoms, the vinyl radical, the 3,3,3-trifluoropropyl radical, the gamma-glycidoxypropyl radical and the gamma-methacryloxypropyl radical with the provision that at least 70% of the R radicals are methyl, and thereafter ceramifying the coating by heating at a temperature of about 200.degree. C. to 1000.degree. C. The use of the coating composition comprising an aqueous alkanol dispersion of colloidal silica and partial condensate of RSi(OH).sub.3 allows for the formation of thick planarizing coatings on the electronic substrate.