High Aspect Ratio EHD Printing with High Viscosity Ink Ejection

J. Choi, S. Lee, Y-J Kim, S.U. Son, K.C. An
Sungkyunkwan University, KR

Keywords: EHD, printing, ejection, aspect ratio, high viscosity ink


EHD (Electro-hydro-dynamics) printing technology, one of the printing technologies based on EHD discharging theory, can be patterning of high resolution and high aspect ratio compared to conventional inkjet printing systems. We have been investigating to define the optimal regions of EHD printing, including ink conductivity and viscosity, to generate a high aspect ratio of line patterns for printed electronics. First, various industrial conductive inks are ejected to find the most suitable ejection mode for feature of patterning using a gate electrode type EHD printing system. Most inks have poor ejection performance with spraying, but some inks exhibit a good pulsed jet mode for the neat patterning. In particular, it requires at most 10-5 S/m of electrical conductivity of inks to be used for a stable pulsed jet mode of ejection; otherwise the ejection tends to appear with spraying. Higher viscosity ink has been patterned with better characteristics than lower viscosity ink on a non-conductive substrate without surface treatment because higher viscosity has retained the formation of pattern without spreadable phenomenon on a substrate using direct type EHD printing system. Also, higher viscosity ink is better to form a higher aspect ratio of patterning than a lower viscosity ink.