Effect of dielectric barrier discharge on surface modification characteristics of polyimide film

Polyimide (PI) films have been used extensively in electronic packaging because of their excellent thermal stability, good mechanical properties, low dielectric constant and good chemical resistance. The effect of dielectric barrier discharge (DBD) plasma treatment on the surface properties and adhesion characteristics of PI films were investigated by means of X-ray photoelectron spectroscopy (XPS), surface free energy analysis and atomic microscopy (AFM). The increasing number of C = O and C–O–C species observed on the surface of the PI films after the DBD plasma treatment is attributable to the oxidation in air of the active species on the PI surface induced by the DBD treatment, and the increase in the surface energy of the PI films treated by DBD plasma is attributed to the improvement in both the polar and London dispersive components. Also, the root mean square roughness (Ra) of the PI film surface was confirmed by AFM observation.