Direct fabrication and morphology of metallic micropatterns by pulsed jet nanoelectrospraying of silver nano-ink

A pulsed jet nanoelectrospray technique was applied to direct fabrication of silver micropatterns. The deposition of a commercial organic silver nano-ink was performed in a fully voltage-controlled fashion by voltage pulses ranging from 550 to 800 V with variable durations. By using 15 μm nozzles, patterns with 100-μm-sized features were locally freeformed on a silicon substrate with a spraying distance of 250 μm. An energy-dispersive X-ray spectrum confirmed metallic silver was developed in all the patterns after heat treatment at 220°C. The size and microstructural evolution of silver films was observed to strongly depend on the deposition volume and material flow over substrate surface. A good linear relationship between the deposition volume and pulse duration was exhibited over the applied voltage range in the cone-jet mode, demonstrating a drop-on-demand capability. By fitting, the deposition volume rate was estimated to be in the range of 0.38-0.59 pL/ms and was shown to increase with the applied voltage.