Fabrication of Conductive Patterns by Laser Irradiation and Thermal Treatment of Silver Nanoparticle Inks for Flexible Printed Electronics

Abstract

Abstract A combination of laser irradiation and thermal treatment of a silver (Ag) nanoparticle (NP) ink was introduced to produce conductive patterns for flexible electronics applications. All of the patterns were laser irradiated followed by thermal treatment. The Ag patterns sintered under formic acid (FA) exhibited increased necking and coalescence. The sheet resistance of the patterns was influenced by sintering atmospheres and the Ag pattern sintered in the FA demonstrated the lowest value of 0.0016 Ω/sq. The hardness values were varied with different sintering atmospheres and the Ag pattern sintered in the FA exhibited the highest hardness value of 4.38 N/mm2. The patterns sintered in different atmospheres exhibited a weight loss in the range of 5.73–7.62% and the roughness varied from 67.95–211.3 nm. This can be attributed to the presence of organic residues after sintering and the degree of NP agglomeration. After conducting folding tests on Ag patterns for up to 50 cycles, all atmospheric conditions exhibited an increasing trend in resistance ratio with each subsequent folding cycle. The Ag patterns that were sintered under air and FA exhibited the lowest and highest resistance ratios of 1.57 and 8.58, respectively.