Low‐Temperature Sintering Copper Inks: In‐Situ X‐Ray Diffraction of Decomposition, Enhanced Conductivity and Morphology, and Nickel‐Improved Weather Resistance

We present a metal–organic decomposition (MOD) copper ink based on copper formate and 1‐amino‐2‐propanol (MIPA), with octylamine (OA) as a printability modifier and nickel formate as an antioxidation additive. X‐ray diffraction (XRD) indicates complex formation and storage stability at low temperature, while Fourier‐transform infrared (FT‐IR) confirms coordination of MIPA to CuF. Thermogravimetric–differential thermal analysis (TG–DTA) shows that the CuF/MIPA/OA complex lowers the decomposition temperature from 215°C (CuF) to ∼130°C; in‐situ XRD detects metallic Cu even at ∼120°C. Copper films sintered on alumina under nitrogen exhibit decreasing resistivity with increasing temperature below 200°C, reaching 2.86 × 10 ⁻⁵ Ω·cm at 180°C for a CuF:MIPA:OA molar ratio of 1:1.3:0.8. Scanning electron microscope (SEM) reveals progressive densification with temperature. Incorporating NiF (5–10 wt%) increases the initial resistivity but markedly improves weather resistance over 35 days. These results establish a coherent low‐temperature route to copper metallization and elucidate how complex chemistry and Ni addition govern conductivity and durability.