The present invention relates to a process for treating a metal substrate to improve adhesion of polymeric materials thereto, comprising the steps of intergranular etching a surface of the metal substrate; and applying an immersion plated metal to the intergranular etched surface by immersing the surface in an immersion plating composition comprising one or more plating metals selected from tin, silver, bismuth, copper, nickel, gallium and germanium. In one embodiment, the immersion plated metal is tin. In one embodiment, the process further comprises a step of adhering the immersion metal plated surface to a surface of a polymeric non-conductive material. In another embodiment, the polymeric nonconductive material is one or more of PTFE, an epoxy resin , a polyimide, a polycyanate ester,a butadiene terephthalate resin, or mixtures thereof. In one embodiment, the process further comprises a step of applying a silane over the immersion plated metal from an aqueous solution of a silane.