Effect of tension on conductivity of gravure printed Ag layer in roll-to-roll process

A curing process as a post-treatment of roll-to-roll (R2R) printing is designed to form a functionality of printed pattern such as conductivity when devices e.g., radio frequency identification, fuel cell, display, and flexible printed circuits board are fabricated by solution-based printing process. Polyethylene naphthalate (PEN) as well as polyethylene terephthalate (PET), which were employed as a flexible substrate, would be stretched much in the post-treatment process due to reduced elastic modulus in high temperature. The elongation of substrate generates cracks inside the printed layer. The formation of crack triggers increasing in electrical resistance and deteriorating in the performance of the device. Therefore, the elongation of substrate should be minimized considering the variations of conductivity of printed layer during the R2R process. In this study, a mathematical model for the relationship among the operating tension, the temperature, and the conductivity of printed layer was developed. The deterioration of conductivity was investigated by observation of cracks in printed layer. The conductivity of printed layer on the stretched substrate was estimated by the proposed model. Also, operating tension was determined for guarantying conductivity even in various temperatures for posttreatment process.