Conclusion An ACF bonding system dedicated for curved substrates has been set up and bonding of polyimide flexcable to curved glass has been successfully demonstrated. Additional experiments have been conducted to figure out how to chemically remove ACF bonding in case any errors occur during he bonding procedure. Dry resist method is promising, seeing its compatibility with chemicals used in TFT fabrication and smooth lamination on curved glass In the future, the goal is to test whether ACF bonding has established successful electrical connections between flexcables and electrodes on curved glass substrates. ZnO TFTs will be driving PZT pixels on curved glass for reduced number of electrical connections PPG Undergraduate Research Fellowship Program Flexible Thin-Film Electronics on Curved Glass Substrates using Anisotropic Conductive Film Bonding Ecenaz Asku, Tianning Liu, and Dr. Thomas N. Jackson Department of Electrical Engineering, Penn State University Introduction Using adaptive optics = mirror figures corrected  increase the collecting area for X-ray telescopes The deposition of piezoelectric Pb[Zr x Ti 1-x ]O 3 (PZT) thin films on the backside of the mirrors = correct the figure error  PZT deform the mirror when actuated. ZnO thin film transistors (TFTs) have been used to address PZT pixels. This has been achieved on flat mirrors using thin film deposition and photolithography techniques. However, the actual mirror in the X-ray telescope is curved and conventional photolithography methods are not trivial given the small features of ZnO electronics. Objective Conventional lithography methods are not trivial on curved glass  electrical connection between PZT and TFTs on curved mirrors, anisotropic conductive film (ACF) area bonding We can area-bond flexible TFT electronics (e.g., ZnO TFTs on polymer substrates) to PZT pixels which are on the curved glass. Electrical connection as well as mechanical bonding are formed when heat and pressure are applied to sandwich the ACF between the electrodes of interest. Methods Method 1: With smooth-surface mandrel of the same curvature, and appropriate pressure setting from the ACF bonding tool, we are able to bond polymers on curved glass. Method 2: Dry resist  lithography and TFT fabrication on dry resist when laid flat  peel off  laminate onto curved surface (with sputtered PZT) Method 3 (future) : Vacuum bag  sealed + heated = heat and pressure for ACF bonding. Results Successful bonding on curved glass  new ACF tool set up completed TFT fabrication completed  acceptable characteristics. Solution-cast polyimide on rigid substrate  5µ free- standing film after mechanical delamination Designed and fabricated flexcables using the reactive ion etching tool, increased surface adhesion of the copper sample with oxygen gas. Pattern generator  new mask made for patterning metals on substrates to test electrical connections by ACF bonding. 500 micron The PPG Undergraduate Research Fellowship Program is supported by the PPG Research Foundation through the Materials Research Institute Acknowledgements Special thanks to PPG Research Fellowship Program, the Materials Research Institute, and Jackson’s Electronic Research Group (JERG). Flex cable bonded with ACF to the glass sample with Cr pattern. Mask pattern with Cr deposition through sputtering Dry resist laminated onto curved substrate. TFT’s on polyimide (PI-2611) TFT characteristics on flexible substrate ACF bonding :Curved glass on mandrel with 220mm curvature and 1.25” height