STUDY OF THE AL PET INTERFACE IN RELATION WITH ADHESION

Thermally evaporated aluminium thin layers have been deposited on two different industrial polyester (PET) films. The peel test shows that adhesion between Al films and PET depends on the heat setting conditions of the PET foils. In order to explain the observed differences in adhesion, ISS analyses were performed on the two surfaces obtained after peeling aluminium from the PET substrates. The Al/PET laminates were also studied by SIMS, RBS and TEM. ISS results show that the failure mechanisms differ for the two samples investigated. Fromthe SIMS depth profiles, a lower sputtering rate is found for the sample presenting a lower adhesion, and RBS spectra show that the Al/PET interface is steeper for this sample. Also, marked differences inthe Al grain sizes are observed by TEM: larger grains without preferred orientation are found on Al layers of poor adhesion.These results are discussed in view of elucidating the influence of the substrate properties on the metal/polymer adhesion.