• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.123-128
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• 2021

Liquid dispensing systems are extensively used in various industries such as display, semiconductor, and battery manufacturing. Of the many types of dispensers, drop-on-demand piezoelectric jetting systems are widely used in semiconductor industries because of their ability to dispense minute volumes with high precision. However, due to the problems of nozzle clogging and undesirable dispensing behavior in these dispensers, which often result in device failure, the use of highly viscous fluids is limited. Accordingly, we studied the behaviors of droplet formation based on changes in viscosity. The effects of surface energy and the inner diameters of needle-type nozzles were also studied. Results showed that nozzles with lower surface energies reduced the ejection volume of droplets when a smaller nozzle diameter (0.21 mm in this study) was applied. These results indicate that the hydrophobic treatment of nozzle surfaces and the use of smaller nozzle diameters are critical factors enabling the use of highly viscous fluids in precision dispensing applications.

• Clean Technology
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• v.22 no.4
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• pp.232-240
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• 2016

Recently, various research studies have been conducted and many are in progress for the suitable alternative materials for ITO based touch screen panel (TSP) due to limitations in size and flexibility. Various researches from all over the world have been attempted to fabricate the fine electrode less than $5{\mu}m$ for the rapid developing of display technology. Research is also being carried out in metal mesh methods using the existing technologies and alternative materials at commercial level. However, by using the existing technologies certain discrepancies are observed like low transparency and low yield which also results in the distortion of patterns. For repairing the damaged pattern, the conventional laser CVD technique has also been used but there are some challenges observed in CVD technique like achieving a stable fine electrode of $10{\mu}m$ or less and avoiding the formation of satellite drops. To overcome these issues, a new printing process named Electrohydrodynamic (EHD) printing, has been introduced by which $5{\mu}m$ fine patterns can be printed in one step. This EHDA printing technique has been applied to print very fine electrodes of $5{\mu}m$ or less by using conductive inks of various viscosities. This study also presents the optimized process parameters for printing $5{\mu}m$ fine electrode patterns during experiments by controlling the applied voltage and supply flow rate. The $5{\mu}m$ repair electrodes were fabricated for repairing $50{\mu}m$ shorted electrode samples.