| abstract |
A composition containing 100 parts by weight of a soluble polyimidosiloxane obtained by polymerization and imidation of an aromatic tetracarboxylic acid component and a component comprising a diaminopolysiloxane, an aromatic diamine with a hydroxyl group and optionally another aromatic diamine, 1 to 50 parts by weight of an epoxy resin, and optionally, also 2 to 150 parts by weight of an inorganic filler such as mica, silica or barium sulfate, and an organic solvent. The composition is homogeneously soluble in organic solvents, and when formed into a protective film on a flexible wiring board it has high heat resistance, flexing resistance, adhesion and chemical resistance (against soldering flux and tin plating solutions). |