Ultra near-field electrohydrodynamic cone-jet breakup of self-reducing silver inks

Ultra near-field electrohydrodynamic (UNF-EHD) jetting of highly conductive self-reducing silver inks is investigated and compared to a theoretical cone-jet breakup model. While models connecting spray angle to fluid properties exist for large substrate-nozzle gap and inks with high ionic conductivity, little is known about the validity of these models when operating under UNF conditions. Using a pulsed cone-jet approach, data on the effects of nozzle height, applied voltage, and waveform (pulse length, pulse frequency, number of pulses/bursts, and delay between bursts) on spot size were collected showing high conductivity inks have a feature resolution very dependent on substrate-nozzle gap.