We have investigated, using X-ray photoelectron spectroscopy (XPS), the surface of polyterafluoroethylene (PTFE) films which were subjected to micromachining by femtosecond UV radiation from an excimer laser (KrF: λ = 248 nm, tp ∼ 380 fs) in air ambient. Bulk characterization of processed PTFE films by Fourier transform infrared spectroscopy (FTIR) allowed us to study laser-induced modifications of the material at energy densities below the ablation threshold. No features in the XPS or FTIR spectra indicated incorporation of hydrogen and/or oxygen or the formation of cross-linked networks of carbon, indicating chemically clean processing in contrast to nanosecond excimer laser processing which chemically degrades the surface being machined. Scanning electron microscopy (SEM) of micrometer size microvias indicates mechanically and thermally damage-free processing of PTFE with good edge quality, again in contrast to nanosecond excimer laser processing.

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