Dependence of surface tension and deposition rate of fluorocarbon polymer films on plasma parameters in a dielectric barrier discharge (DBD)

Fluorocarbon polymer films were deposited on Si, PP and PET foils in a dielectric barrier discharge (DBD) at atmospheric pressure. The deposition rate and surface tension were measured with dependence on external (gas composition, discharge power, discharge gap, pre- and post-treatment procedure) and internal plasma parameter (gas temperature and composition of the plasma). Experiments were performed using as starting molecules the following fluorocarbons: CF4, C2F6, C3HF7 and c-C4F8. Also the influence of additional hydrogen and oxygen on deposition rate and surface tension was investigated. By contact angle measurements with three liquids the polar as well as the dispersive component of surface tension were measured. The results of tension surface measurements correlate to results obtained by FTIR and XPS measurements of the films. It is shown that the amount of CF2- and CF3-bindings in the film is the dominant correlation factor between XPS and surface tension.