Positive-working aqueous base developable photosensitive polybenzoxazole (PBO) precursor/organoclay nanocomposites have been prepared through the addition of an organoclay to a PBO precursor. The organoclay was formed by a cation exchange reaction between a Na+-montmorillonite clay and an ammonium salt of dodecylamine. The PBO precursor used in this study was a polyhydroxyamide that was prepared from a low-temperature polymerization of 2'2'-bis(3-amino-4-hydroxyphenyl) hexafluoropropane and 4,4'-oxydibenzoyl chloride with an inherent viscosity of 0.3 dL/g. The photosensitive resin/clay formulations were prepared from the precursor with 2,3,4-tris(1-oxo-2-diazonaphthoquinone-5sulfonyloxy)-benzophenone photosensitive compound and 3-5 wt % organoclay. The PBO precursor/clay was subsequently thermally cared to PBO/clay at 350 degrees C. Both X-ray diffraction and transmission electron microscope analyses showed that the organoclay was dispersed in the PBO matrix in a nanometer scale. The thermal expansion coefficient of PBO/clay film, which contained 5 wt % organoclay, was decreased 33% compared to the pure PBO film. The PBO/clay nanocomposite films also displayed higher thermal stability, glass transition temperature, and water resistance than the pure PBO film. The photosensitive PBO precursor/clay nanocomposite showed a line/space pattern with a resolution of 5 mu m and its sensitivity and contrast were not affected by the organoclay. (c) 2005 Wiley Periodicals, Inc.