Synthesis of submicron sized silver powder for metal deposition via laser sintered inkjet printing

Submicron sized silver powder was prepared from AgNO₃ using a chemical-reduction method. A spherical silver power exhibiting an average particle size distribution of 0.2–0.4 μm and an excellent dispersibility was achieved and applied to the inkjet printing process. A drop-on-demand (DOD) inkjetting system was used to print the silver particles suspended in a terpineol solvent. Through sintering at 300 °C, the size of the particles adjacent to the borderline of droplets were gradually increased and necking was observed between the droplets. Alternatively, the substrate for the particles could be heated to a lower temperature, and the sintering process of the conducting line was completed by the application of a laser beam. Increase in the laser power reduces the resistivity of the line. Through microstructure analysis, the necks between droplets were sintered at a specific energy density (ψ = 0.0398 J mm⁻³). The conducting lines were soldered and of a larger aggregation, between which a discontinuous micro-crack was observed. This was attributed to the surface tension effect and shrinkage during solidification. Influence of the densification parameters on resistivity was significant.