Adhesion and permeability of polyimide-clay nanocomposite as protective coating for microelectronic gas sensor

Abstract

Polyimide-clay (PI-clay) nanocomposite was prepared from solution of poly (amic acid), precursor of 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride and p-phenylenediamine, and dodecylamine-montomorillonite. Fourier transform infrared spectroscopy, thermogravimetric montomorillonite. Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and atomic absorption spectrosocopy were used to verify the incorporation of modifying agents into the structure of clay and intercalation of modified clay into the polyimide matrix. Both PI and PI-clay films were subsequently prepared by means of solution casting techniques. Gas permeability, resistivity, and adhesion properties were determined. In the case of gas permeability, only 3 wt% addition of clay brought permeability of O₂ gas to values less than half of that of unfilled polyimide. Furthermore, this hybrid showed an improvement in electrical resistivity due to the prevention of electrical tree growth by clay particles. More importantly, adhesion between the films and silicon was increased with increasing clay content.