High rate coating of plastic films and plastic sheets with clear oxide layers

For the coating of moving substrates, bipolar technology with a dual magnetron sputtering system is recommended (see Fig.1). Here the two magnetrons alternately act as anode and cathode. In this way a metallic anode is also available over long operation times despite the presence of the reactive gas. If the chosen frequency is high enough, charging on the insulating layers is limited which would otherwise result in troublesome arcing. Typically, pulse generators with a sine wave or a square wave shaped output with a medium frequency of 50-100kHz in bipolar mode are used as power supply.