Study of pretreatment methods for vacuum metallization of plastics

In this study some aspects of the vacuum metallization of plastics and composite materials were investigated from an industrial point of view. The study involved the most commonly used substrate materials being ABS, PC, PP and a composite (glass fiber/epoxy resin) material. Substrates were subjected to industrially feasible pretreatments such as flame treatment, chemical treatment, mechanical treatment, oxygen plasma and also a lacquer treatment. Surface characterization before and after the pretreatments has been done by atomic force microscopy, X-ray photo-electron spectroscopy and contact angle measurements. An aluminium layer was deposited by magnetron sputtering to nominal thicknesses of 0.1 and 1.0 μm. The adhesion of the metallic layer was studied by the cross-cut test (ISO 2409) and the falling-weight test (ISO 6272), two standardized methods that can be easily performed in an industrial environment. The results indicate that these tests can only be used for a go or no-go decision on the adhesion.