METHOD AND DEVICE FOR MICROWAVE PLASMA DEPOSITION OF A COATING ON A THERMOPLASTIC CONTAINER SURFACE

摘要

The invention concerns the deposition of a coating on a thermoplastic container surface (3) using low pressure plasma by excitation of a precursor gas with UHF electromagnetic waves in a circular shaped vacuum cavity (1) receiving the container. It consists in dimensioning the cavity (1) with respect to the frequency of the UHF electromagnetic waves so as to obtain a coupling mode generating several electromagnetic fields inside the cavity. In particular a TM 120 coupling mode is provided which generates two central fields (4A, 4 B) inside the cavity, whereby two containers (3) can be simultaneously treated in said cavity (1).