We report an innovative application of an Inductively Coupled Plasma (ICP) to surface treatment of a plastic material. The plasma was created by applying a low power 13.56 MHz radio frequency to a λ/4 antenna outside the plasma chamber in low pressure conditions, thus giving rise to a capacitively coupled plasma in the so-called E-mode, below the mode switching to a real inductive plasma (H-mode). The working gas was either Argon or Nitrogen at working pressures in the range from 0.1 to 1 mbar. The plasma has been characterized by convenient techniques: Langmuir-probe analysis has been used to relate the physical properties to the treatment working conditions, while optical spectra have been acquired to understand the chemical reactions of the treatment.
With this source, a plasma treatment has been performed on a plastic material. The application was a plasma etching on a PolyVinylChloride (PVC) film. This plasma source is especially well suited for very long treatments thanks to the lack of vacuum feed-through, therefore the film could be exposed to the plasma for about two hours. The result was the superficial generation of double C=C bonds. Investigations with a FIB/SEM microscope revealed the presence of bi-dimensional clusters with average radius of about 200 nm.
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