SUMMARY

Scalable manufacturing of patterned thin films constitutes a persistent challenge for printed flexible electronics. In principle, liquid phase physical deposition techniques are well-suited to minimize cost and material waste. In practice, however, existing methods are either limited by material property requirements or penalized by costly auxiliary processing steps. The objective of this work is to introduce novel coating methods to process heterogeneous films in arbitrary 2D patterns, based on a hybrid tool that integrates working principles of slot die coating and ink-jet printing. These methods extend the scalability, simplicity, and robustness of coating to multiple liquids simultaneously in patterns such as stripes, patches or arbitrary digital patterns.

An experimental investigation will be carried out using prototype tooling incorporated into a custom roll-to-roll system for in-situ imaging of deposition phenomena. It has been shown from preliminary results that coating flows are a complex intersection of creeping flow within the tool, deformation of variable volume liquid bridges at deposition, and wetting behavior of the liquid film. For simultaneous coating of two fluid phases, miscibility has been found to be a key requirement for liquid bridge stability. In addition, response of the liquid bridge to flow actuation has been linked to the precision of complex pattern features. Further experimental characterization will focus on minimum pattern feature size, process sensitivity to inputs and materials, and classification of unique flow phenomena. Dimensional analysis will be used to aid the physical interpretation of these results. Simple computational models will also be developed to provide physical intuition of the coating process, and to inform expectations for future application of the novel processing techniques.