Copper Nano/Fine Particles as JoiningMaterials for Low Temperature Sintering

This study reports on the development of a novel technology focusing on sub-oxide copper nanoparticles to meet the demand for low-temperature sinterable conductive materials and sintered bonding materials in the electronics industry. As a low-cost, high-performance alternative to conventional silver nanoparticles, the research established an efficient synthesis method for copper nanoparticles containing Cu<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">64</inf>O and Cu<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</inf>O structures and successfully created pastes using these particles. Using a chemical reduction method, copper nanoparticles containing sub-oxides were synthesized with controllable particle sizes ranging from a few nanometers to about 200 nm. Notably, the successful synthesis of core-shell nanoparticles was achieved, confirming that sub-oxide copper transforms into metallic copper at temperatures below 100°C. This phase transition promotes “necking” between materials even at low temperatures, forming strong bonds.