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pp.476-481
Among the various roll-to-roll printing technologies such as gravure, gravure-offset, and reverse offset printing,reverse offset printing has the advantage of fine patterning, with less than 5µm line width. However, it involves complexprocesses, consisting of 1) the coating process, 2) the off process, 3) the patterning process, and 4) the set process of the ink.Each process demands various ink properties, including viscosity, surface tension, stickiness, and adhesion with substrate orcliché; these properties are critical factors for the printing quality of fine patterning. In this study, Ag nano ink was developedfor reverse offset printing and the effect of polyvinylpyrrolidone(PVP), used as a capping agent of Ag nano particles, on theprinting quality was investigated. Ag nano particles with a diameter of ~60nm were synthesized using the conventional polyolsynthesis process. Ethanol and ethylene glycol monopropyl ether(EGPE) were used together as the main solvent in order tocontrol the drying and absorption of the solvents during the printing process. The rheological behavior, especially ink adhesionand stickiness, was controlled with washing processes that have an effect on the offset process and that played a critical rolein the fine patterning. The electrical and thermal behaviors were analyzed according to the content of PVP in the Ag ink. Finally,an Ag mesh pattern with a line width of 10µm was printed using reverse offset printing; this printing showed an electricalresistivity of 36µΩ·cm after sintering at 200oC.
