Preparation of micron-sized plate-like silver powders used in silver paste by wet-chemical reduction method

The micron-sized plate-like silver powders were prepared through wet-chemical reduction method using silver nitrate as the precursor, stearic acid as the dispersant, and ascorbic acid as the reducing agent. The effects of different types and the content of protective agents and the reaction solution adding methods on the shapes, particle size distribution, and other parameters of plate-like silver powders were investigated in the present work. When the sulfuric acid (2% of the mass of silver nitrate) is used as a protective agent, the plate-like silver powders with D50 = 6.52–11.48 μm were successfully prepared by adding the reducing solution into the silver nitrate solution dropwise. Moreover, the conductive silver paste made from as-prepared silver powders was screen printed on polyethylene terephthalate substrate to test the resistivity. Interestingly, the sintering time and temperature have significant effects on the resistivity, and the conductive paste exhibits a good conductivity of (2.19–2.27) × 10−6 Ω·m after sintering at 150 °C for 30 min. The results indicated that it is feasible to directly prepare plate-like silver powders by the wet-chemical reduction method, and the plate-like silver powders can be applied in the field of conductive silver paste.