Micromachining of polyurethane (PU) polymer using a KrF excimer laser (248 nm)

•We examine the micromachined surfaces of polyurethane polymer.•The effect of various operating parameters on micromachining are investigated.•Experiment performed in air and under water environments with different mask size.

Polyurethane (PU) polymer, due to its biocompatibility, weather resistance, and favorable physical properties, finds a number of applications in medical implants, protective coatings, and as a prototype material for structural components in MEMS devices. An excimer laser (wavelength = 248 nm, FWHM = 25 ns) is employed for micromachining of polyurethane (PU) polymer. For air environment, the ablation rate is 0.18 μm/pulse and for underwater environment, the ablation rate is 0.07 μm/pulse (with underwater ablation threshold as 0.10 J/cm2), which concluded low taper angles (∼32°) for in air as compared to high taper angles (∼65°) with underwater micromachining. The experimental results for air and under water micromachining demonstrate ablation process as a combination of photo-thermal and photo-chemical mechanism.