Present embodiments provide for a polymer film with a reflective ratio equal to or above about 80%, comprising a white polyimide layer and a white adhesive layer disposed on a surface of the white polyimide layer The white adhesive layer including an adhesive agent and a white filler distributed in the adhesive agent. Present embodiments also provide for a lighting assembly that comprises a substrate, a lighting component disposed on the substrate, and a reflective surface formed by the polymer film.