Highly Densified Cu Wirings Fabricated from Air-Stable Cu Complex Ink with High Conductivity, Enhanced Oxidation Resistance, and Flexibility

The microstructure of printed Cu wirings fabricated from air-stable Cu complex inks is greatly modified by low-temperature curing followed by intense pulsed light densification enhancement treatment. The resulting almost full densification of printed Cu wirings enables them to possess a high electrical conductivity of 50% bulk Cu. The dense structure also largely prevents the permeation of oxygen and water into the inner side of the Cu wirings, thereby improving their oxidation resistance and maintaining a stable resistance (R/R-0 < 1.5) even after 1000 h aging at 85 degrees C-85% RH. In addition, the dense and robust structure can improve the resistance to crack generation and propagation in Cu wirings during the bending, so as to improve their flexibility. The relative resistance of Cu wirings can be kept below 1.2 after 1000 bending cycles. All the results indicate that these highly densified Cu wirings fabricated from air-stable Cu complex inks can be used to replace the noble metallic Au and Ag wirings for practical application in flexible electronics.