The influence of moisture on atmospheric pressure plasma etching of PA6 films

The moisture in the substrate material may have a potential influence on atmospheric pressure plasma treatment. In order to investigate how the existence of moisture affects atmospheric pressure plasma treatment, polyamide 6 (PA6) films were treated by helium, helium/oxygen (O₂) plasmas using atmospheric pressure plasma jet (APPJ) at different moisture regain. The film surfaces were investigated using contact-angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to characterize the surfaces. The exposure of PA6 film surfaces to the plasmas led to the etching process on the surfaces and changes in the topography of the surfaces. It was shown that the etching rate and the surface roughness were higher for the 9.33% moisture regain (relative humidity 100%) group than that of the 1.61% moisture regain (relative humidity 10%) group with the same plasma gas and power.