3 39 biphenyltetracarboxylic acid dianhydride 2 3 3 39 4 39 biphenyltetracarboxylic acid dianhydride 3 3 39 4 4 39 benzophenonetetracarboxylic acid dianhydride 2 3 3 39 4 39 benzophenonetetracarboxylic acid dianhydride 2 2 39 3 3 39 benzophenonetetracarboxylic anhydride bis 3 4 dicarboxyphenyl ether dianhydride bis 3 4 dicarboxyphenyl sulfone dianhydride 1 2 5 6 naphthalenetetracarboxylic acid dianhydride 2 3 6 7 naphthalenetetracarboxylic acid dianhydride etc concrete examples of the diamines expressed by the formula 3 are as follows str12 among these silicone diamines those having a number average molecular weight in the range of 400 to 8 000 are suitable the n in the formula 3 is determined so that the number average molecular weight of the compound of the formula 3 may fall within the above range if the number average molecular weight of the silicone diamine is less than 400 varnishes containing a silicone polyimide precursor prepared from such a silicone diamine according to the same process as in the present invention have a low viscosity and have no sufficient coating properties contrarily if the number average molecular weight exceeds 8 000 the resulting silicone polyimide procursor has a reduced solubility in solvents and hence it is not practical concrete examples of the aminosilicon compounds expressed by the formula 4 are as follows the above raw material compounds may be reacted in solvents as described below concrete examples of such reaction solvents are n methylpyrrolidone dimethylacetamide dimethylformamide dimethylsulfoxide tetramethylurea pyridine dimethylsulfone hexamethylphosphoroamide methylformamide n acetyl 2 pyrrolidone toluene xylene methyl cellosolve ethyl cellosolve butyl cellosolve diethylene glycol monomethyl ether diethylene glycol dimethyl ether cyclopentanone cyclohexanone etc these solvents may.