‘Clean-on-Demand’ film could boost yields for roll-to-roll flexible electronics

Paul Boughton

As part of the EU-funded, Holst Centre-co-ordinated Clean4Yield project, DuPont Teijin Films (DTF) is developing a new ‘Clean-on-Demand’ PET polyester film that could boost yields and cut costs for roll-to-roll (R2R) production of flexible electronics. The new film features a protective layer that keeps the active surface of the film clean and free from particulate contamination until it is used, reducing defects.

High yields are essential for commercially viable mass-market flexible electronics. This latest development from DTF directly addresses one of the key issues affecting flexible electronics yields: defects caused by particulate contamination on the substrate. The new Clean-on-Demand film is covered with a protective layer that is removed immediately before depositing the barrier layer that protects the sensitive flexible electronics circuitry from the environment (the first step in producing a flexible electronic device).

Moreover, initial trials suggest that depositing and then removing the protective layer can change surface topography. Together, the lower contamination and altered surface smoothness allow high-quality barriers to be created using less material, significantly reducing manufacturing costs. In tests performed at Holst Centre, the Clean-on-Demand film with a single-layer silicon nitride barrier has already achieved water vapor transmission rates of just 5 x 10-5g /m2 /day – around an order of magnitude better than today’s commercially available films.

“Although further work is required to commercialize the Clean-on-Demand film, these results show its potential to greatly reduce a major source of contamination in R2R production. Being part of the Clean4Yield project was crucial in our ability to develop the film. The project had the foresight to identify yields and particle contamination as the key challenges, and gave us the opportunity to explore solutions. It also brought us together with partners like Holst Centre, whose testing and insight helped accelerate development,” said Valentijn von Morgen, Senior Process Engineer at DuPont Teijin Films.

“DTF’s Clean-on-Demand film had some of the best water vapor transmission results we’ve ever seen with a silicon nitride barrier. Developing the film is part of Clean4Yield’s multi-pronged approach to addressing yield in R2R production of flexible electronics through the detection, cleaning, prevention and repair of defects and contamination. By bringing together partners from across the value chain, Clean4Yield provides an ideal setting for research and product development in this emerging market,” says Clean4Yield Project Manager Juliane Gabel of Holst Centre.

For more information, visit www.clean4yield.eu