Influence of Surface Treatments on The Metallization of Thermostable Polymers

We have investigated the properties of metal/polyphenylquinoxaline (PPO) bonds as a function of polymer surface treatments. PPO, which starts to decompose at 550°C, was spin coated onto silicon wafers. Copper was sputtered with a DC magnetron machine and gold was evaporated with an e-gun under ultra-high vacuum conditions. Surfaces and interfaces were characterized by X-ray photoemission spectroscopy (XPS) and contact angle measurements. The adhesion of the metal layer was measured by the peel test. For the untreated surface, the peel strength is increased by annealing and the failure becomes cohesive. For the hydrophilic UV oxidized surface, the peel strength is lower than that for the untreated surface and is further decreased by annealing. CuO, which is a catalyst for the PPQ degradation, has been evidenced on the failure surface and is formed by interaction between copper and the highly oxidized carbon atoms. The properties of polymer surfaces irradiated by an excimer laser in air are dominated by the presence of debris which provokes the growth of metal clusters.