In the field ofroll-to-roll manufacturing, the accurate prediction and elimination of the tension disturbance in a flexible web are critical because of the unexpected deformation occurring in the roll-to-roll process. Although the causes of the tension error have been examined, no analytical models have been developed to estimate the tension disturbances in an industrial roll-to-roll process accurately. In this article, an advanced model was developed to determine the tension disturbances caused by the run-out arising from the axis mismatch, roundness error, and unbalance, and the velocity variation of the rollers on an industrial-scale roll-to-roll printing process. The estimation performance of the developed model was experimentally verified, and a high average accuracy of 92.4% was attained. Finally, the model was used to determine the maximum permissible run-out caused by the axis mismatch, roundness error, and unbalance of the roller in an industrial-scale roll-to-roll printing process. This model can be universally used to troubleshoot the tension disturbances in roll-to-roll multilayer printing and functional film manufacturing processes and, thereby, facilitate the mass production of highly integrated flexible and foldable electronics.

Slot-die coatings are advantageous when used for coating large-area flexible devices; in particular, the coating width can be controlled and simultaneous multi-layer coatings can be processed. To date, the effects of ink widening and the coating gap on the coating thickness have only been considered in a few studies. To this end, we developed two mathematical models to accurately estimate the coating width and thickness that consider these two effects. We used root mean square deviation (RMSD) to experimentally verify the developed method. When the coating gap was increased, the coating width increased and the coating thickness decreased. Experimental results showed that the estimated performances of the coating width and thickness models were as high as 98.46% and 95.8%, respectively. We think that the developed models can be useful for determining the coating conditions according to the ink properties to coat a functional layer with user-defined widths and thicknesses in both lab- and industrial-scale roll-to-roll slot-die coating processes.

In roll-to-roll (R2R) processing, web uniformity is a crucial factor that can guarantee high coating quality. To understand web defects due to thermal deformation, we analyzed the effect of web unevenness on the coating quality of an yttria-stabilized zirconia (YSZ) layer, a brittle electrolyte of solid oxide fuel cells (SOFCs). We used finite-element analysis to study thermal and mechanical deformations at different drying temperature levels. A YSZ layer was also coated using R2R slot-die coating to observe the effect of web unevenness on coating quality. Web unevenness was generated by thermal deformation due to conduction and convection heat from the dryer. Because of varying web unevenness with time, the YSZ layer developed cracks. At higher drying temperatures, more coating defects with larger widths were generated. Results indicated that web unevenness at the coating section led to coating defects that could damage the SOFCs and decrease yield in the R2R process. Coating defects generated by web unevenness caused by convection and conduction heat should be considered in the high-volume production of brittle electrolytes using the R2R process.