Hannover Messe 2019 Printing curved conductor tracks: The curved touchscreen
Besides foldable smartphones, some firms are also working on bendable displays. For this, the INM has developed new additive technologies.
In photo-chemical metallisation, colourless silver compounds are transformed with the help of a photo-active coating when UV light falls on it, says the INM (Leibniz Institute for New Materials). Using various methods, tracks or other structures are created on plastic films or glass: by means of UV lasers, conductor tracks can be “written”; UV-permeable photo-masks or transparent stamps, which displace the silver compound mechanically, are suitable for larger-scale applications. This enables tracks of different dimensions to be imaged to a thousandth-of-a-millimetre.
In a further printing process, the scientists make nano-particle inks from TCOs, such as indium-tin oxide (ITO), for inkjet or gravure printing: “We produce nano-particles with particular characteristics from the TCOs,” explains Peter W. de Oliveira, director of the Innovation Centre at the INM. “The TCO ink then results from the addition of a solvent and a special binding agent. This leads not only to good adhesion of the TCO particles on the film, but also raises the flexibility of the TCO coating.” This apparently preserves the conductivity when the films are bent. The coating becomes functional after hardening with UV light at low temperatures below 130 °C.
Visit INM – Leibniz-Institut für Neue Materialien at Hannover Messe in Hall 5, Booth C54.