SURFACE-PROPERTIES OF CHEMICALLY-MODIFIED POLYIMIDE FILMS

Surface modification of Kapton polyimide film (325 nm thick) by means of chromic acid and perchloric acid at different times and temperature s has been carried out. The contact angle of water decreased from 82 t o 55 degrees and the surface energy increased accordingly from 26 to 4 5 mJ/m(2) with times of etching by chromic acid up to 45 min at 33 deg rees C. Etching at higher temperatures increased the surface energy. C hromic acid was more effective than perchloric acid. IR and XPS studie s indicated multiple bonding and generation of poler groups on the sur face. The peak at 1778 cm(-1) due to the imide group decreased on acid etching. The O/C ratio increased and the N/C ratio decreased. The pee l strength of the joint polyimide film/copper film/epoxy adhesive/alum inium sheet increased about two-fold on modification of the polyimide (PI) film at 33 degrees C for 45 min, although the changes were margin al for the PI film/silicone rubber/PI film joint. The peel strength is a function of the time and temperature of etching.