Wearables, arched displays and buildings facades increasingly require bendable, flexible surfaces with tailored functionality and properties. These coating functionalities include the reduction of gas permeation, protection against chemicals, radiation and mechanical contact as well as conductive coatings and layers with specific optical properties.
Surfaces are equipped with thin functional layers to achieve these properties and functionalities. Increasing productivity and efficiency of these coating processes is an important focus of our applications-oriented research.
One of these deposition technologies is plasma-enhanced chemical vapor deposition (PECVD). Fraunhofer FEP is active in the field of improved PECVD processes for high productivity and efficient application in roll-to-roll coating equipment. These processes provide large-area, cost-effective coating of flexible substrate material. In contrast to conventional processes, Fraunhofer FEP employs magnetrons and hollow-cathodes as plasma sources.
“The development of our hollow-cathode PECVD process has provided us with a versatile tool for the deposition of silicon-containing plasma polymer layers on flexible substrates,” said Michiel Top, project manager in the Flat and Flexible Products division at Fraunhofer FEP. “The process not only allows us to scale up to web-widths up to four meters but can also be directly combined with other deposition techniques like sputtering and evaporation in a single facility.”
Dynamic coating rates of up to 3000 nanometers for 1 meter per minute web-speed have been attained for plasma polymer layers. It was shown that the water vapour transmittance of an inorganic barrier coating can be reduced by up to 50% by in-line deposition of a polymer-like protective layer.