polyimide firm is the best thun-film type insulating material in nowadays world, using the polymerization of PMDA and DDE in strongly polar solvent, followed by cast film formation and imidization., which has a good property of resistance to heat, electrical insulation, adhesion, radioactive and chemical. It can be used in a long term during the temperature between -269℃. to 260℃.. it can also be used under 400℃. in a short term.
