Processing-Structure-Property Relationship In Direct Laser Writing Carbonization Of Polyimide

Direct laser writing carbonization (DLWc) of polyimide has recently emerged as a versatile method for facile fabrication of a variety of functional devices. Up-to-date, there is still a lack of comprehensive and in-depth experimental studies to understand the processing-structure-property relationship involved in this promising technique. With assistance of methylene blue adsorption as an in situ porous structure characterization method along with scanning electron microscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy, and electrical property measurements, we systematically investigate the multiscale structure evolution and the electrical sheet resistance of the carbon lines fabricated by DLWc at varied laser processing conditions. The key processing parameters being investigated included: laser power (P), laser beam scanning speed (S), distance of laser beam waist to the surface of polyimide film (D), and their combined effect-the averaged areal laser energy density-(E). Quantitative relationships are established between these processing parameters and the specific surface area, the porosity, the degree of perfection of the layered carbon or graphitic basic structure units, as well as the electrical sheet resistance of the carbon lines created by DLWc. The comprehensive and quantitative processing-multiscale structure-electrical property relationships for DLWc established in this study expect to be useful for better understanding the complicated photo-thermally induced polyimide pyrolysis/carbonization process.