Fine conductive line printing of high viscosity CuO ink using near field electrospinning (NFES)

Modern printed electronics applications require patterning of fine conductive lines of sufficient thickness. However, the two requirements for pattern width and thickness are a trade-off. To print fine pattern at a micrometer size, the nozzle diameter must be approximately the size of the pattern width, so only low-viscosity inks are used. As a result, the pattern is likely to be very thin and multiple overlapping printing is required for sufficient conductance. In order to use high viscosity ink for fine patterning, near field electrospinning (NFES) is attracting attention because it can print very thin and thick patterns using large nozzles (high-viscosity ink). Until now, silver paste ink has been used for microconductive patterning using electrospinning. However, Ag nanoparticle (NP) inks are expensive. In this study, we report the use of a relatively inexpensive CuO NP ink for electrospinning-based printing. For implementation, the material preparation, printing and post-processing process are discussed. For post-processing, a continuous wave (CW) green laser with a 532 nm wavelength was used to reduce the CuO to Cu and sinter the nanoparticles. After sintering, the 50 μm width and 1.48 μm thick Cu conductive line exhibited a resistivity of 5.46 μΩ·cm, which is 3.25 times of the bulk resistivity of Cu.