Norzafriza Nitta, Tomohiro Ishii, Yoshihiro Sato, Hidemichi Fujiwara
It is well known that the metal nanoparticle features a melting point depression as opposed to the bulk metal material because of the size effect. It is possible for the metal nanoparticle to sinter at a relatively low temperature and we are interested in the metal nanoparticle as a conductive material for the printeded electronics applications. This study investigated the effect of the surface state of the copper nanoparticles and the polyol decomposition on the copper nanoparticle sintering process using the copper particle because of its advantageous cost and the polyol as the typical solvent. When the oxidation degree of the copper nanoparticle was low, the ketones were detected as the decomposition material, and since the ketones have a weak reduction apability, the effect of the nanoparticle on the sintering of the copper nanoparticles was low. However, in the case of the higher oxidized copper nanoparticles, the carboxylic acids were detected as the decomposition material, which had a leaching effect and the copper oxide was reduced in association with the decomposition process, the effect on the sintering of the copper nanoparticle was high. The optimization of the oxidation degree of the copper nanoparticle and the interaction between the oxidized copper nanoparticle and the polyol accelerated the grain growth of the sintered particles and the electric resistivity decreased. The crack in the obtained sintered film decreases. The oxidation degree is one of the most important factors for the development of the copper nanoparticles in the future.
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