Proton-assisted low-temperature sintering of Cu fine particles stabilized by a proton-initiating degradable polymer

Abstract

Metallic copper fine particles were prepared by chemical reduction of CuO in the presence of thermally degradable poly-1,4-butanediol-divinylether (BDVE). Because a BDVE thin layer formed on the particle surfaces, the obtained copper particles were stable and did not undergo obvious oxidation under ambient conditions. The ether groups of BDVE were hydrolyzed with protons, and this generated small fragment molecules. The BDVE-stabilized copper fine particles and their pastes can be therefore sintered at 150 °C in the presence of protons. Electro-conductive films with a relatively low resistivity of 8.5 × 10⁻⁵ Ω cm were obtained on a alumina substrate in the presence of formic acid, and hot pressed conductive pellets with a resistivity of 2.9 × 10⁻⁵ Ω cm were also obtained without any pre-oxidative annealing in the presence of proton generator molecules at very low temperatures. The hot pressed pellets show a high anti-oxidative ability and their corrosion tests revealed their good anti-corrosion property.