Patent ID: 8809688

Claim:
A polyamic acid solution comprising: (a) 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, and pyromellitic dianhydride as an aromatic tetracarboxylic acid dianhydride; (b) at least one aromatic diamine comprising p-phenylenediamine and 4,4′-oxydianiline; (c) an organic solvent; and (d) an inorganic filler, wherein the p-phenylenediamine and the 4,4′-oxydianiline are used in a ratio range of 55-85:15-45 mol %, said at least one aromatic tetracarboxylic acid dianhydride (a) and said at least one aromatic diamine (b) are mixed in a ratio range of a:b=1.05:1.00-1.00:1.05 mol, and the polyamic acid has a viscosity of 3,000 to 50,000 cps.