Aromatic Polyimides Based on 3, 3’-Dimethyl-4, 4’-Diaminodiphenylmethane as Potential Material for Interlayer Dielectrics in RF MEMS Circuits

New aromatic polyimides have been synthesized by polycondensation reaction of 3, 3’-dimethyl-4, 4’-diaminodiphenylmethane with benzophenon tetracarboxylic dianhydride or hexafluoroiso propylidene diphthalic anhydride in N-methylpyrrolidinone as a solvent, followed by chemical imidization in the presence of acetic anhydride and pyridine at 100°C for 4 h. The obtained polyimides exhibited excellent solubility, high thermal stability and good film forming ability. The degree of cure of polyimides has been observed to have a profound influence on the fluorescence of the films.