As part of the Polysafe project funded by the German Federal Ministry of Education and Research (BMBF), the Fraunhofer FEP developed a new process for the deposition of metal coatings in a roll-to-roll process. In this process, the metal layers are applied to the polymer films by electron beam evaporation. The research team was able to demonstrate the deposition of copper and aluminum layers up to 1 µm thick on 12 µm thick PET films. The deposition took place in a roll-to-roll process on a roll width of up to 60 cm.
Claus Luber, technical project manager, explains: "The challenge was to design the polymer films and the coating process in such a way that a thickness of the current collector comparable to current metal foils and optimum electrical conductivity of the metal layer could be guaranteed." The aim was to gain a holistic understanding of the influence of the parameters of the belt run, substrate pre-treatment and metal evaporation and to develop optimum process settings to achieve the technological and economic requirements. Another challenge was to minimize the thermal load during the deposition process.