Sustainable Production Process for Capacitor Foil

The current production process for capacitor foil consists of a metal refinement process to 99,99% aluminium quality followed by casting of rolling slabs. The slabs are hot and cold rolled down to a final thickness of about 100 µm. After degreasing, annea ling is done to create a cubic texture suitable for tunnel etching. During the subsequent tunnel etching process the effective surface area is increased by a factor of 20. Finally a dielectric layer is produced by an electrochemical process (anodising). T he energy consumption of the last process step for High Voltage (HV) capacitor foil is 130 kWh/kg-produced foil. This is 10 times more than the energy required for primary aluminium production. We have identified three crucial steps in the production pro cess: i) the production of a rolled foil suitable for tunnel etching, ii) the etching step itself, and iii) the final energy-demanding dielectric layer formation. This project will focus on i) and iii). A process for making the dielectric layer based on electrophoresis of dispersed nanosized particles is proposed. The aim is to develop this process to a level required for making a decision of industrial utilisation. There is a great potential for energy saving if this new process rout is implemented. The whole thermomechanical process route will be studied with the aim of finding the crucial parameters influencing the tunnel etching properties. These results will be used in order to optimise the process and reducing cost. The project aims at making t he industrial partners robust against the increasing competition from Asian capacitor foil producers