Cost-Effective and Low-Temperature Sintering of Oxidized Copper Nanoparticles for Power Electronics

As power electronics continue to advance, the demand for cost-effective and highly reliable interconnection materials has increased. Sintered metal nanoparticles, particularly copper (Cu), have gained attention as a promising alternative to lead-free solder due to their high electrical and thermal conductivity. However, conventional sintering processes often require high temperatures and reducing atmospheres, which limit their applicability in industrial settings. This study investigates the low-temperature sintering of slightly oxidized copper nanoparticles (Cu<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> O-NPs: X = 64 or 8) under cost-effective and practical conditions. We developed a novel approach that utilizes a mild reducing agent combined with a controlled sintering atmosphere to achieve efficient densification at temperatures below 200°C. By optimizing the nanoparticle size, oxidation state, and sintering conditions, we successfully improved the mechanical properties of the sintered Cu structures. The sintered Cu demonstrated a resistivity close to that of bulk copper and exhibited excellent adhesion, making it suitable for power electronic applications. Furthermore, this low-temperature process eliminates the need for expensive reducing environments such as hydrogen gas, significantly reducing manufacturing costs and enhancing process safety. The proposed sintering approach is highly attractive for next-generation electronic packaging and interconnections.