Metal Conductive Surface Patterning on Photoactive Polyimide

Current fabrication methods for metal interconnects and contacts are generally based on conventional photoresist fabrication procedures that require expensive equipment and multiple material/time‐consuming steps. In this work, a photopatternable polyimide is synthesized via the copolymerization of a functional diamine monomer with a 1,4‐dihydropyridine side‐chain which can decompose under UV irradiation into a pyridine group—a promising ligand for palladium ions. After the absorption of palladium ions, the electroless copper plating is carried out to form metal patterns of copper. Copper patterns with smooth boundaries are confirmed by scanning electron microscope and atomic force microscope. Robust interfacial bonding between the copper and the polyimide film is evidenced by Scotch tape adhesion tests. The photopatternable polyimide has the advantages of low Pd consumption, easy operation without expansive equipment. The linear thermal expansion coefficient of the photopatternable polyimide remains close to the one of copper wire, demonstrating the adaptability of the photopatternable polyimide for integrated circuit application. This work presents the approach of (i) the synthesis of a novel photopatternable polyimide and (ii) its application for making flexible conductive metal structures and patterned metal interconnects, which can be expected to have tremendous potential in the field of flexible electronics.