Sintering Process Study On Paper-based Flexible Circuits Based On Nanosilver Conductive Ink

With the development of lightweighting and flexibility of electronic products, thetraditional rigid printed circuit boards can not meet the requirement of currentelectronic components. Paper, as a substrate for fabricating flexible electronics, couldpotentially cause a breakthrough in the electronics world. Not only are paper-basedcircuits lightweight, biodegradable, it can be rolled or folded into3D configurations.Thus，doing research on the conductive ink, printed technology, and sintering processrelated to paper-based circuits is vatial.Firstly，the silver nanoparticles covered by surfactant were synthesized in anaqueous by reducing silver nitrate （AgNO3） with sodium borohydrede （NaBH4） in thepresence of poly（vinyl pyrrolidone）（PVP） as a stabilizer. Prepared silvernanoparticles were characterized using TEM, SEM, and XRD. Then, the silvernanoparticles adsorbed by a small amount of PVP as conductive phase, weredispersed in ethanol, and ethylene glycol and glycerol were added to adjust theperformance of the ink. The solid loading of silver nanoparticles for ink was10wt%²0wt%.A kind of conductive pen was designed, prepared with nanosiver ink as theconductive composition and rollerball pen as the writing implement, and used todirect-write conductive patterns on Epson photo paper. Meanwhile, ink-jet printingwas also tried by converted Epson printer R230.Heat sintering and hot-pressure sintering were adopted to make the direct-writingpatterns conductive. Compared with heat sintering, hot-pressure sintering decreasedthe sintering time and reduced the resistance of the direct-writing coating. Under theoptimal hot-pressure sintering process, a typical resistivity value measured was1.37×10^-7Ωm, eight times as much as bulk silver.At the end, a series of test results showed that the paper-based circuit bydirect-writing and hot-pressure sintering had well stability and mechanical flexibility.A simple working circuit was prepared, driven by the3.0V power supply, the3.0VLED could work normally, which demonstrates the promising application for thepaper-based electric circuits.