Fabrication of high-resolution conductive line via inkjet printing of nano-palladium catalyst onto PET substrate

In this paper, a method to fabricate high-resolution conductive metal line on a flexible PET substrate is described. This method involves inkjet printing of a thermo-sensitive St-co-NIPAAm/Pd nanoparticle-based ink on an untreated polymer to create the catalytic site, onto which nickel is subsequently deposited by an electroless plating method, to obtain the desired width and conductivity of the metal line. The Pd nanoparticles reduced and stabilized by styrene-N-isopropylacrylamide co-oligomer showed their well dispersion in the water without surfactant and reductant in the mixture and these nanoparticles adhered well to untreated PET surface. Through a systematic study with a variety of inkjet variables such as firing voltage and droplet spacing, the optimum inkjet parameters were obtained. The adhesion of the deposited Ni–P coating to the substrate was ascertained by the scotch tape test method. The line width and electrical resistivity were examined as function of electroless plating time. The procedure was successfully applied for manufacturing high-resolution conductive metal line.