ScholarWorks@성균관대학교

초록

This study evaluates the thermal performance of a hot-air drying chamber for roll-to-roll (R2R) flexible electronics using experiments and three-dimensional heat transfer simulations. A computational fluid dynamic model incorporating a moving reference frame for the polyethylene terephthalate film was developed in ANSYS Fluent (ANSYS Inc., USA) and validated against measured surface temperature data over film speeds ranging from 10 to 90 mm s-1, yielding errors below 10.4%. At 90 mm s-1, the baseline chamber with 6 mm distributor holes showed a time-averaged spatial coefficient of variation ( CV & horbar;s) of 3.87% and a temporal coefficient of variation ( CVt) of 1.84% in the transverse direction. Increasing the distributor hole diameter from 6 to 8 or 9 mm resulted in little to no improvement in transverse temperature uniformity, due to the reduced jet momentum and enhanced thermal stratification. In contrast, a multi-diameter configuration (6 mm bottom half, 7 mm middle quarter, and 8 mm top quarter) effectively compensated for hydrostatic pressure drop, ensuring balanced airflow, enhanced mixing, and fewer recirculation zones. This optimized design reduced CV & horbar;s to 2.18% and CVt to 1.71%, representing improvements of 43.67% and 7.07% relative to the baseline case. As a result, the chamber delivered more uniform and stable thermal conditions, particularly in the downstream region which critically governs the drying process. The proposed multi-diameter distributor design offers a simple and cost-effective retrofit that significantly enhances thermal uniformity, which is expected to reduce drying-related defects such as cracking, delamination, and poor adhesion in printed electronics. These results offer practical guidelines for optimizing thermal design in high-performance R2R drying systems.

키워드