Enduring and Stable Surface Dielectric Barrier Discharge (SDBD) Plasma Using Fluorinated Multi-Layered Polyimide

In this work, multi-layered polyimide (PI) films were surface fluorinated at 328 K and 0.05 MPa using F(2)/N(2) mixture with 20% F(2) by volume, for a fluorination time of 0, 30 and 60 min, respectively. Then, they were subjected to discharge plasma as barrier dielectrics of surface dielectric barrier discharge (SDBD) at ambient atmospheric air. The dielectric lifetime of SDBD greatly extends after 60 min surface fluorination. In addition, optical emission spectroscopy (OES) results indicate that during the plasma processing, SDBD with fluorinated PI can obtain more stable plasma parameters, including gas temperature and electron temperature. Dielectric surface properties were further evaluated by infrared thermography, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). It is considered that both physical and chemical effects lead to the extension of dielectric lifetime. The physical effect is reflected in low surface temperature and increased surface roughness, while the chemical effect is reflected in the graft of fluorine groups.