Abstract

Vacuum co-evaporation of polymer materials and metals or their compounds allows the production of thin layers of specific properties. The method is technologically convenient and presents a certain alternative to the "sol-gel" technologies. Composite thin layers (1-1.5 μm) have been obtained by the simultaneous evaporation (10 A/sec) of two monomers (oxydiamline and pyromellitdianhydride) and a metal. As metal a thermally evaporated Al (0.6 A/sec) or an organometalic compound [(CH₃)₃NAlH₃] have been used. The Al-organic compound is thermally decomposed during the first stage of imidization taking place at a temperature of 173 - 177 °C. Electron micrographs exhibit evenly distributed Al particles in the volume of the polyimide matrix with very small dispersivity values (2.5 - 5.0 nm - 90%). The second thermal stage od imidization (270 °C) does not cause coalescence of Al particles. It is assumed that a micro metal synthesis occurs by the build-up of strong C-O-Al bonds which fix the aluminium clusters. The optical parameters of the obtained composites have been measured at the various stages of the imidization process of the matrix. XeCl laser action (308 nm, 30 nsec, 30 to 4000 mJ/cm²) on the materials has been studied envisaging possibilities for micro-structuring. X-ray photoelectron spectroscopy in the exposure area shows a shift of Al₂O₃ (2.4 eV) which is higher than the Al photoelectron peak (1.7 eV). It is suggested that the laser action does not only break the imide bonds, but also stimulates the course of the chemical reaction on the particles' surfaces. Scanning micrographs demonstrate that the laser ablation process influences the average size of the Al particles.

© 1996 IEEE