Adhesion Improvement of Copper Nanopaste on Glass Surface Modified by Atmospheric-Pressure Plasma

Printed electronics are beginning to make a gradual advance into commercial applications such as radio frequency identification tags, sensors, and displays. One of the concerns for commercialization is weak adhesion of directly-printed conductive nanoink/nanopaste. For adhesion enhancement, atmospheric-pressure plasma (APP) treatment was conducted on a glass substrate before screen printing. The best wettability of samples was obtained at the plasma power of 150 W, oxygen flow ratio of 30 sccm, and 6 treatments. While the screen-printed copper (Cu) nanopaste was scratched, its adhesion was evaluated in terms of critical friction. By the optimal condition of APP treatment, the critical friction forces of the Cu/glass system increased by approximately an average of 81% in the sintering temperature range from 250 degrees C to 400 degrees C. The Cu nanopaste sintered at higher temperatures on the APP-treated glass substrate showed a mixed interfacial failure mode of buckling and spallation due to higher critical friction forces. The APP-treated glass surface was modified to be more hydrophilic with the higher surface energy, which is attributed to the adhesion enhancement of the Cu/glass system.