This paper discloses the recent evolution of flexible substrates with conductive film patterns by use of inkjet patterning of UV curable resist, etching process, and then striping the resist film in sequence. The UV curable ink has a viscosity of about 8∼20cps and surface tension of 30∼40 dyne/cm at operation temperature, which is appropriate for the inkjet printing process conducted on the ink at an elevated temperature. Experimental results indicated that the single drop size on the conductive film is about 75∼80μm. For the continuous line pattern, the minimum line width and line spacing of the printed resist can reach from 80 μm/60 μm to 80 μm/20 μm, and the resist thin film thickness is 5μm. After the etching and striping process, the conductive line width and line spacing can be 80 μm/20 μm. This low-cost and easy process is potentially promising to flexible electronics in the future.
Chung-Wei Wang, Wen-Chun Chen, Kevin Cheng, Yuh-Zheng Lee, "Inkjet Patterning of UV Curable Etching Resist for Flexible Conductive Circuit Electrodes" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP23), 2007, pp 855 - 858, https://doi.org/10.2352/ISSN.2169-4451.2007.23.1.art00084_2