Multi nozzle electrohydrodynamic inkjet printing head by batch fabrication

We report a multi nozzle electrohydrodynamic (EHD) printing head by using batch fabrication for the first time. Inks can be ejected from a glass nozzle by applied large electric field. Tiny nozzles with a outer diameter of 100 microns are fabricated by sand blasting on a glass wafer. A stable continuous jetting with a commercial carbon black ink was observed. Continuous lines with a width of 30 microns on a silicon wafer were printed simultaneously with a DC bias voltage of 1.7 kV at the stage speed of 500 mm/s. Separated dot patterns with a diameter of 20 microns were printed with various jetting frequency up to 10 kHz on a super-hydropobic teflon coated silicon wafer. Also continuous line width can be reduced to 20 microns on a hydrophobic surface.

INTRODUCTION

As electronics industry becomes mature, need for low cost fabrication technology get stronger. One of the candidates for reducing the fabrication cost is to substitute traditional photolithography by direct printing. Due to the recent development of inkjet printing technology, there are several applications using piezoelectric inkjet printing process in a mass production of liquid crystal display (LCD) such as color filter or polyimide layer. But the conventional piezoelectric inkjet printing technology has several problems such as nozzle clogging, limited viscosity range of ink, and difficulty for printing of continuous lines.