Preparation of nano-silver nanoparticles for conductive ink and the correlations with its conductivity

Nano-silver conductive ink meets the development demands of the flexible printed electronic products. The size of silver nanoparticles (AgNPs) was closely connected with the conductivity of the printed pattern. In this study, AgNPs were prepared, correlated with its conductivity. AgNPs were characterized by SEM, HR-TEM, UV–Vis, and XPS. The sintering methods of AgNPs were compared. The results showed that the optimum conditions of AgNPs with high conductivity were as follows: the molar ratio of polyvinylpyrrolidone to silver nitrate was 1.8:1, the concentration of silver nitrate was 0.05 mol/L, and the concentration of hydrazine hydrate was 2 mol/L. The particle size of AgNPs with a face-centred cubic structure was around 60 nm. Using sodium chloride as sintering agent at room temperature, AgNPs could get close to each other and sinter faster in comparison with the sintering at high temperature, and the sheet resistance of nano-silver film arrived at 1.2 × 10–5 Ω m.