METHOD FOR PREPARING POLYIMIDE FILM HAVING LOW DIELECTRIC CONSTANT AND HIGH FRACTURE TOUGHNESS

摘要

The present invention discloses a method for preparing a polyimide film having a low dielectric constant and high fracture toughness. The method comprises: first preparing an aromatic diamine solution, and then grinding and well mixing a carbic anhydride-maleimido heptaisobutyl polysilsesquioxane alternating copolymer and aromatic dianhydride; adding the mixture to the aromatic diamine solution, and then stirring to obtain a carbic anhydride-maleimido heptaisobutyl polysilsesquioxane alternating copolymer/polyamide acid solution; uniformly applying the carbic anhydride-maleimido heptaisobutyl polysilsesquioxane alternating copolymer/polyamide acid solution to a clean glass sheet, and then placing the glass sheet in a vacuum drying cabinet for treatment; cooling the treated glass sheet to room temperature and then putting same in water for ultrasonic peeling of a film, and vacuum drying the film to obtain a target product. The dielectric constant of the film obtained in the present invention is reduced to 2.2, the breaking elongation is increased by 272%, and the tensile energy is increased by 285%, so that the breaking elongation and tensile energy are greatly increased, and thus the fracture toughness is good.