Synthesis of Conductive Nano Ink Using 1-Octanethiol Coated Copper Nano Powders in 1-Octanol for Low Temperature Sintering Process

Abstract

A conductive nanoink was prepared using copper nanoparticles (CNPs). In order to prevent the oxidation of CNPs, the particles were coated by 1-octanethiol using Vaporized Self-Assembled Multi-layers (VSAMs) method. The coating of 1-octanethiol onto CNPs was confirmed by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Dispersion stability of CNPs was checked by monitoring its viscosity over 6 weeks. The sheet-type of patterned samples using the fabricated ink was sintered at 350 and 230 degrees C, respectively. Electrical resistivity was measured to be 5.69 x 10(-8) Omega.m when sintered at 350 degrees C and 7.67 x 10(-8) Omega.m when sintered at 230 degrees C. These results were 3.4 and 4.6 times than the value for bulk copper. During the sintering process, the optimum temperature of removing organic materials was found to be 200 degrees C. This removal temperature dramatically influenced necking and the density of samples. Therefore, 1-octanethiol VSAMs and 1-octanol ink were used successfully for the low-temperature sintering process to fabricate conductive Cu patterns by finding the optimum temperature of 200 degrees C for complete removal of organic materials prior to the sintering process.