Preparation of hybrid layers consisting of copper nanoparticles and polyimide matrix via polyol in situ reducing process

Hybrid layers consisting of copper nanoparticles and polyimide have been successfully fabricated using copper nitrate as the copper precursor and pyromellitic dianhydride/oxydianiline-(PMDA/ODA-) based polyimide films as the substrate. The fabrication method relies on the potassium hydroxide-induced chemical modification of the polyimide surface to introduce carboxylic acid groups, the incorporation of copper ions through subsequent ion exchange reaction, and followed by the polyol in situ reduction of copper ions contained polyimide layers in ethylene glycol solution at 197 degrees C. The amount of copper ions in the modified layer strongly depended on the ion exchange time. The copper nanoparticles size changed from 3 nm to 27 nm when the reduction time increased from 5 min to 30 min. These experiments provided an efficient route for copper metallization of polyimide substrate. The detailed reaction progress and resulted films were characterized by Attenuated total reflection-Fourier transform infrared, X-ray photoelectron spectroscopy, inductively coupled plasma atomic emission spectrometer, X-ray diffraction, transmission and scanning electron microscope.