he film preparation method is as follows: polyamide acid solution flow forming film, stretching, high temperature imide.Thin film is yellow transparent, relative density 1.39 ~ 1.45, has outstanding high temperature resistance, radiation resistance, chemical corrosion resistance and electrical insulation properties, can be used in 250 ~ 280ºC air for a long time.The vitrification temperatures are 280ºC(Upilex R), 385ºC(Kapton) and above 500ºC (Upilex S), respectively.The tensile strength is 200MPa at 20ºC and greater than 100MPa at 200ºC.It is especially suitable for flexible printed circuit board base material and insulation material of various high temperature resistant electric motor.