Tension modeling and precise tension control of roll-to-roll system for flexible electronics

Abstract This study proposes the design of a roll-to-roll system for flexible electronics that enables accurate and precise tension control. It analyzes the factors for change in the tension of a roll-to-roll system and develops a tension model for each section to successfully predict the tension that is applied to such a system, the sagging of film according to tension, and deformation due to residual stress. This series of modeling processes allow engineers to design a roll-to-roll system for flexible electronics. Both a velocity control method for the tension between in-feeder and out-feeder—where there is no change of roller radius—and torque control method for the tension in modules like the rewinder, where the roll radius changes, are proposed. A roll-to-roll system according to the proposed design procedure and tension control methods was manufactured and experimented on under various test conditions. The accuracy and precision of velocity control between the in-feeder and the out-feeder were 100.01% and 1.15%, respectively, whereas those of torque control between the out-feeder and the rewinder were 99.9% and 1.35%, respectively, both at one sigma. The experiments confirmed that the two proposed types of tension control methods were accurate and precise. The experimental result with a monitoring sensor showed that the modeling was valid and that an accurate roll-to-roll system minimizing tension reduction was built. This study successfully demonstrated roll-to-roll system design and control techniques that are applicable to various pieces of roll-to-roll process equipment.