Improving reliability of silver nanoparticle thin films

Abstract

Solution-based direct metal printing methods without conventional microfabrication processes are drawing a significant attention as the next generation manufacturing processes for low-cost electronics applications. Gold or silver nanoparticles with size from a few to tens of nanometers are typically used as the materials of metal nanoparticle-based ink solutions for the printed flexible electronics fabrication process. In this master`s thesis, we present four methods to improve reliability of silver nanoparticle thin film. First, we investigated the adhesion characteristics by double cantilever beam (DCB) test of silver nanoparticle thin film on the silicon substrate. Basing on the results of DCB test of fracture mechanics, using SEM, AFM, XPS and other analytical equipment, we can propose a bridging mechanism of improving the reliability of the nanoparticle thin film. Second, we made nanocomposite by adding nanowires into nanoparticle thin film like rebar in a concrete. From the research results, there were almost no micro-cracks that formed in the existing thin film, and even there were cracks, nanowires were bridging between the cracks maintaining electrical and mechanical properties. The third solution is the effects of UV-Ozone treatment decomposing the organics of nanoparticles surrounded by organic shells. By removing the organics shells that block self-cohesion within the nanoparticles, higher reliability was obtained for more nanoparticles were induced to contact each other intimately. In addition, nanocomposite and UV-Ozone treatment measured the resistance of the thin film on the polymer substrate under tensile. Lastly, evaluating the characteristics that porous nanoparticle thin film will be sensitive to moisture is the solution. Through the subcritical test, an effect of moisture was forming crack growths and nanoparticle resistance to moisture was investigated.