Coating solution for forming flat-surface insulating film, flat-surface insulating film-coated substrate, and production method of a flat-surface insulating film-coated substrate

摘要

A coating solution for forming a flat-surface insulating film, which is a coating solution obtained by dissolving a poly(diorgano)siloxane A having a mass average molecular weight of 900 to 10,000 and a metal alkoxide B in an organic solvent C and further adding water, wherein the molar ratio A/B of the poly(diorgano)siloxane A to 1 mol of the metal alkoxide B is from 0.05 to 1.5, the organic solvent C has a hydroxyl group, the solubility of water in 100 g of the organic solvent C is from 3 to 20 g, and the molar ratio C/A of the organic solvent C to 1 mol of the poly(diorgano)siloxane A is from 0.05 to 100. This coating solution for forming a flat-surface insulating film ensures that an organic modified silicate composed of a poly(diorgano)siloxane and a metal alkoxide can be formed as a thick film having 1 μm or more and can be an organic modified silicate insulating film causing no irregularities due to phase separation and having a low Young's modulus and flexibility high enough to follow the deformation of a substrate board, as well as high film surface flatness allowing for mounting of microcomponents of an electronic device or the like.