High temperature-assisted electrohydrodynamic jet printing of sintered type nano silver ink on a heated substrate

Sintered type silver ink has been widely applied in photovoltaics and piezoceramics due to its unique electrical and mechanical properties. This study presents a high temperature-assisted electrohydrodynamic jet (HTAEJ) printing technique for direct printing high aspect ratio micro-scale silver structures using sintered type silver ink. It makes use of an external electrical field force to form a focused jet to produce fine features using a large sized nozzle. During the printing process, a certain temperature is necessary to accelerate evaporation of the solvent in the just printed structure, to hold its original printed feature. It was found that a high temperature of 200 degrees C generated by a heating substrate can help to produce fine silver structures using the electrohydrodynamic jet printing technique. A sintered type nano silver ink was prepared for HTAEJ printing. Unique equipment with a heating platform and a cooling fixture was designed and produced for HTAEJ printing of sintered type silver ink. Besides, the printing parameters of temperature, electric field strength and motion speed have been investigated to achieve a stable jet and desired printed silver structures. It was demonstrated that the HTAEJ printed silver structure has a width of 50 mu m, an aspect ratio of 0.4 and a resistivity of 6.5 mu Omega cm. Furthermore, 3D silver micro-pillars with a diameter of 20 mu m and height of 80-120 mu m were produced using the HTAEJ printing technique.