Fluorinated Heterocyclic Polyimides for Potential Use in RF MEMS Devices

A series of fluorinated polyimides containing oxadiazole rings and hexafluoroisopropylidene groups in the main chain were prepared by polycondensation in solution at high temperature of hexafluoroisopropylidene diphthalic dianhydride with aromatic diamines containing preformed oxadiazole ring. These polymers are soluble in polar aprotic solvents and show remarkable film-forming ability. The free standing films exhibit low dielectric constant and strong adhesion to various substrates. The polymers are highly thermostable with decomposition temperature being above 470degC and glass transition above 220degC. All these properties make the present polymers potential candidates for applications as high performance materials.