Method for treating polyamide acid by using ultrapure water and application of method

The invention relates to a method for treating polyamide acid using ultrapure water and application of the method. The method comprises the following steps: first reacting dianhydride monomer and diamine monomer in an organic solvent, so as to obtain a solution of polyamide acid with a viscosity average molecular weight of 10000-30000; leveling the polyamide acid solution in a glass tank into a thin film with the thickness of 0.5 mm to 1.5 mm, then adding ultrapure water into the glass tank until the entire polyamide acid is precipitated into a thin film, and then washing the thin film; wrapping the thin film by using filter cloth, and then performing centrifugal separation; and soaking the polyamide acid thin film in an ethyl alcohol-acetone-isopropanol solution for 15 min to 25 min, taking out for drying, and dissolving the polyamide acid thin film in a polar solvent. The method for treating the polyamide acid by using the ultrapure water, disclosed by the invention, is easy to operate, greatly reduces the