Solvent Pre-wet of R2R Micro-contact Printing

• Main Authors: Hsien Che Kuo, 郭憲哲
• Other Authors: John Cheng
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/99537946470339086082

碩士 === 國立中正大學 === 機械工程學系暨研究所 === 103 === Our group has devoted to flexible electronics fabrication for a long time and been focused on fabricating patterned organic thin films. One major research issue is how to make a uniform organic thin film with patterns in atmospheric environment. And our group develops a innovative micro-contact printing (μCP) process with solvent pre-wetting technique. It can improve the uniformity of printed thin films when we use the poly(dimethyl siloxane) (PDMS) as the printing stamp. The solvent pre-wetting has been proved useful in μCP, but nowadays we don't have a reliable criterion to determine if the pre-wetting is enough or not. In this thesis, an effective criterion for solvent pre-wetting has developed. Specifically, variations in the contact angles on the pre-wetted PDMS stamp is proposed for the pre-wetting criterion. The experiment result shows the best coating result is when the standard deviation of contact angles is lower than 0.5 degree. To implement the pre-wetting criterion on a roll-to-roll (R2R) machine, we use a web camera to take pictures of the pre-wetted PDMS along with the droplet of a testing liquid, and then use image processing algorithms to calculate the contact angles for pre-wetting evaluation. At last we combine the solvent pre-wetting and self-adjusting blade coating, another previous technique developed in our group, to print large-area thin films without patterns by using a prototype R2R μCP machine. We successfully print large-area poly(3-hexyl thiophene) (P3HT) thin films with dimensions of 5.5 cm x 100 cm and 20 cm x 100 cm, respectively. Finally, possible improvements to the prototype R2R μCP machine regarding self-adjusting blade coating, thickness uniformity of PDMS ring stamps, parallelism among rollers and environmental controls were identified for future high quality R2R μCP printing.