Laser ablation behavior and mechanism of polyimide by UV irradiation

A research focused on ablation characteristics of polyimide (PI) film induced by a nanosecond ultraviolet (UV) laser was presented. The effect of varying the laser power (P), scanning speed (S) and their combined impact – linear laser energy density (LLED) on the ablation behavior on PI was investigated. The characteristics of both photothermal and photochemical ablation regimes were observed, which extremely depend on LLED. A relatively narrow interference ablation region (~43 μm) was observed at low LLED (< 3 J/m) and a typical photothermal ablation area (~101 μm) was observed at high LLED (> 6 J/m) accompanied with thermal expansion and cracks. The surface morphology and composition was analyzed using SEM, EDX, and Raman spectroscopy. Then through TGA-FTIR and Py-GC–MS technique, the composition of the residue and the decomposition process were discussed in detail. The experimental results and developed mechanism offer some insights into the characteristics of UV laser ablation of PI film.