Recent Developments of Optimized ITO Coatings on Ultra-Thin Flexible Glass in S2S and R2R processes
The functionalization of ultra-thin glass surfaces leads to changes of the mechanical properties of the substrate-layer-compound. This has enormous consequences for further process steps to complete the manufacture of a device or product, especially in roll-to-roll processes. We investigated several ultra-thin flexible glass types with thicknesses of 50 µm and 100 µm relating their mechanical strength in uncoated state and after coating with ITO thin-films. We studied the influence of several process parameters during the PVD coating on the mechanical reliability of the substrate-layer-compound, especially on the mechanical film stress, the bending radius, the hardness, and the Young’s-modulus. The ITO thin-films are grown in the pilot-scale in-line coating machine ILA900 in sheet-to-sheet process on a maximum flexible glass size of 600 x 600 mm². By variation of the sputtering process parameter, we matched the mechanical film stress under consideration of the electrical and optical properties of the ITO films. We report about the transfer of the optimized sputter process to the pilot scale roll-to-roll coater FOSA labX 330 for applying ITO thin-films on flexible glass in a roll-to-roll process.