▎ 摘　　要

NOVELTY - Preparation of polyimide composite film comprises grafting nano-silica with amino groups on the surface and fluorinated graphene with oxygen-containing groups, dispersing in N,N-dimethylformamide, sonicating, and stirring; and adding to a polyamic acid solution, casting and subjecting to thermal imidization, where mass ratio of the mixed solution to the polyamic acid solution is 1-5:100. USE - The method is used for preparing polyimide composite film for printed circuit board (claimed). ADVANTAGE - The composite film has low dielectric constant and dielectric loss and meets the requirement of high frequency signal transmission of the printed circuit board.