Surface modification of Ag-coated Cu particles using dicarboxylic acids to enhance the electrical conductivity of sintered films by suppressing dewetting in Ag shells

A resin-free paste containing 1.5 μm Cu@Ag particles was fabricated and used to form a film with excellent electrical conductivity even after a significantly high-speed sintering process. The particle surfaces were treated using three types of dicarboxylic acids, namely OA, SA, and PA, with carboxyl groups to suppress the dewetting behavior of Ag shells generated during thermal sintering. SEM, UV–vis, FT-IR, Raman spectroscopy, XPS, and TG-DTA analysis were performed to verify the morphological changes, chemical binding states (formation of an organo-metallic surface), and thermal behavior changes on the particle surfaces after surface treatment. The PA-modified particle surface exhibited a delayed dewetting behavior and the most suppressed oxidation degree. Furthermore, the paste containing the surface-modified particles exhibited a significantly low electrical resistivity (5.05 × 10⁻⁶ Ω·cm) after sintering for just 1 min at 300 °C under N₂, which is an improvement of approximately three orders of magnitude over the original paste. Consequently, the surface treatment using effective dicarboxylic acid, which simultaneously inhibited Ag dewetting and suppressed Cu oxidation, improved Ag sintering between particles and enhanced the electrical properties of the sintered film.