Air‐Sintering of Dual‐Ligand Capped Copper Nanoparticles for High‐Temperature Interconnect Applications

ABSTRACT Copper nanoparticles (CuNPs) have promising applications in energy storage, sensing, and chip manufacturing because of their excellent properties and low cost. However, oxidation limits their sinterability and performance at high temperatures. Here, dual‐ligand CuNPs with oleylamine and ethylenediamine were synthesized and optimized. The results confirm that the dual‐ligand structure facilitated the continuous release of reducing NH 2 groups and formed a stable inert H 2 O/CO 2 atmosphere, effectively suppressing the oxidation of CuNPs during air sintering. Residual bidentate ethylenediamine ligands further enhanced the oxidation resistance of sintered structures at elevated temperatures. The optimized CuNPs could achieve ultralow resistivity: 6.91 μΩ cm at 300°C and 4.99 μΩ cm at 350°C, and exhibit high‐temperature oxidation resistance comparable to bulk Cu. When utilized in conjunction with flexible capacitive pressure sensors, the optimized CuNP sintered electrodes exhibited notable sensing stability, retaining robust signals for 100 cycles even at 350°C. The findings underscore the great potential of dual‐ligand CuNPs for high‐temperature antioxidant applications.