The low modulus polyimide adhesive compositions of the present invention contain a low modulus polyimidosiloxane polymer, a thermosetting substantially-non-halogenated epoxy (optionally including an epoxy catalyst), a plasticizer, an insoluble halogen-free flame-retardant filler, and optionally an adhesion promoter. The adhesive can be applied upon (or incorporated into) flexible circuits using a relatively low lamination temperature, generally no higher than 200, 190, 180, 175, 170, 165, 160, 155, or 150.degree. C. The adhesive is generally resistant to unwanted curl even in cases where the adhesive polyimide and the base film polyimide have a coefficient of linear thermal expansions (measured between 50.degree. C. and 250.degree. C.) that differ by more than 10, 15, 20 25, or 30 ppm/.degree. C.