Decomposition of poly(amide-imide) film using atmospheric pressure non-equilibrium plasma generated in a stream of H2O/Ar mixed gases

Atmospheric pressure non-equilibrium Ar-H2O plasma was irradiated to exfoliate a thin film of a heat-resistant polymer, poly(amide-imide) coating on enamel copper wire. The plasma was produced by applying microwave power inducted with Ar-H2, Ar-O2, Ar-H2O or Ar-H2-O2 mixed gases. The poly(amide-imide) thin film was exfoliate by those plasma irradiations. The magnitude of exfoliation depended on the distance of the copper wire from the plasma generating material and reached a maximum at a distance around 4cm for each plasma irradiation. Surface conditions of the copper wire varied depending on the inducted gases. Ar-O2 plasma irradiation oxidized the copper surface while other plasmas kept the copper surface unchanged. The time it took to exfoliate the poly(amide-imide) depended on the irradiation source, either Ar-O2 (within 60s), Ar-H2O (within 70s), Ar-H2-O2 (within 70s) or Ar-H2 (within 125s). The Ar-H2O plasma irradiation under non-equilibrium atmospheric pressure was found to be the best method for exfoliating the poly(amide-imide) thin film coating on enamel copper wires rather than the Ar-H2-O2 plasma because of its simplicity and safety.