Contribution of Electrohydrodynamic (EHD) Inkjet Printing for micro-LED Display Fabrication and Evolution to Multi-Nozzle EHD Inkjet Printhead

Recently, as the growth of the technology and market of printing based displays, demands and importance of high-resolution printing technology have been increased rapidly. Solution-based inkjet printing fabrication process has advantages of rapid and large area fabrication, low cost and easy tunability.
The electrohydrodynamic (EHD) jet printing method was suggested to one of the alternatives and advanced printing technique. The EHD jet printing uses a force balance of electrical force and fluid dynamics to control jetting phenomena. This could allow the smaller droplet generation than nozzle size and ejection of a wide range of ink viscosity. Due to these advantages, more precise and smaller patterning of different materials was possible such as silver or QD inks in micro scales. These high-resolution patterning also have the advantage of suppressing the coffee-ring effect from its extremely small droplet size.
In this talk, we present the successful contribution of EHD Inkjet technology for micro-LED display development. For example, we could fabricate the bond-pads for transferring chips and repair the electrodes of display panels. We also could make uniform small dots of QDs. Recently we opened multi-nozzle EHD inkjet printhead in a market and tried to apply for micro- LED display. This multi-nozzle EHD inkjet printhead could show high performance of high resolution printing and high production capability.