Physico-chemical Insights on Tuning the Morphology of a Photosensitive Polyimide by UV Laser Irradiation

An aromatic photosensitive polyimide is prepared from 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 4,4'-diaminodiphenyl methane and its structuring ability upon UV-laser exposure is investigated. Surface modification is performed at two laser fluences, i.e. 89 and 244 mJ/cm2, and different number of pulses. The changes of the surface morphology, induced by the employed patterning technique, are examined. According to atomic force microscopy data cone-like structures are formed and their appearance mechanism is analyzed taking into account the laser irradiation conditions. Surface wettability tests reveal an intensification of hydrophobic character, which may be ascribed to the formation of a thin carbon-enriched layer at the polyimide surface.