Improved thermal stability of adhesion for an epoxy resin and a polyimide to copper has been achieved by pretreating the copper surface with polybenzimidazole solution. The adhesion strength for modified specimens was found to be twice of that for unmodified after aging at 250-degrees-C for 30 min. The coupling mechanism and interfacial structure of the copper-polymer composites have been investigated by surface enhanced Raman scattering and differencial scanning calorimetry.