Printable Thick Copper Conductors from Optically Modulated Multidimensional Particle Mixtures.

Printing techniques that enable the formation of arbitrarily designed architectures have been implemented in various research fields owing to their characteristic advantages in processing over other techniques. In particular, low-cost, printable conductors are of paramount importance in the production of highly functioning printed electronics. Among various candidates, copper (Cu) particle-based printable fluid has been regarded as the most promising constituent material in conjunction with the use of the flash-light-sintering (FLS) process in air. In this study, we synthesized surface-oxidation-suppressed Cu nanoparticles, sub-micronparticles, and flakes to regulate the optical absorption characteristics in FLS-processed, Cu-based printed conductors. Our results revealed clearly that the critical issues in FLS-processed conductors, namely, undesirable crack formation and a limitation of thickness, are resolved by adjusting the optical behaviors of particulate layers by variation of the composition of multidimensional mixture particles. It is suggested that crack-free, 13.2 μm thick printed Cu conductors can be generated with a resistivity of 11.4 μΩ cm by printing and FLS processes in air. The proposed alternative approach is demonstrated with electrical circuits comprising electrodes and interconnections.