A Novel Method to Guarantee the Specified Thickness and Surface Roughness of the Roll-to-Roll Printed Patterns Using the Tension of a Moving Substrate

TLDR

Roll‑to‑roll continuous printing is a promising mass‑production method for flexible electronics, but its quality depends on substrate flexibility, ink formulation, printing method, and curing. The authors model the ink‑transfer process, linking dynamic surface roughness to web tension, and construct simple design‑of‑experiment meta‑models to capture this relationship. Experiments confirm that pattern thickness and surface roughness are governed by web tension, with optimal tension and precise tension control being essential for achieving the desired specifications.

Abstract

Roll-to-roll (R2R) continuous printing is an attractive technology for mass-producing flexible printed electronics. Many studies have been conducted in this field. The application of the R2R printing process, however, requires information pertaining to system parameters such as substrate flexibility, ink formulation, and printing method as well as the curing method for conductive ink. We show that the quality of a printed pattern (thickness and surface roughness) could be affected by tension variation of the flexible bare substrate in spite of the optimal settings of the ink, substrate, and printing method. In addition, an ink-transfer mechanism for the R2R printed electronics is analyzed to reveal the relationships between the dynamic surface roughness and tension of a moving web. Since the dynamics of the physical problem are complex, simple meta models using a design of experiment are developed. The experimental results are found to be in agreement with the meta models. It is found that the two important factors for achieving the desired thickness and surface roughness of the R2R printed patterns are optimal tension and control accuracy of the operating tension.