Fabrication of Conductive Patterns by Inkjet Printing of Silver Nano-suspension

摘要

Micro droplets of silver nano-suspension were inkjet printed onto glass substrates. The ink adopted in this study was made by dispersing synthesized silver nano-particles sized at about 4 nm into DI water at 30 wt%. An inkjet printing system with a piezoelectric printhead was used to print and patterned micro droplets. The bipolar pulse waveform employed in driving the piezoelectric printhead was set to be 2 μs for t_(rise), 5 μs for t_(dewell), 2 μs for t_(fall), 5 μs for t_(echo), and 2 μs for tfinalrise. Steady droplet evolution without satellite formation could be observed at a driving pulse voltage of ±20 V. Prior to printing, the glass substrate surfaces were treated by O_3 plasma to promote cleanliness. Single droplets of 30.95 μm were jetted on the treated substrates. Patterns including lines, square surfaces and their combinations could be successfully printed on substrate. Line patterns with various droplet interspaces sizes of 10, 20, 30, and 40 μm were printed and discussed. Moreover, the morphologies of line patterns were also investigated under different substrate temperatures of 25, 50, and 90°C in this study. In order to eliminate the protecting agent effectively, the substrates were subjected to heat treatment at 300°C with a heating rate of 1°C/min. The heat treated silver line exhibited electrical resistance about 8.59×10~(-3) Ω-cm at 360 nm thickness.