Abstract
Polyether(ether)ketone (PEEK) has been widely used in the electronics and biomedical industries due to excellent electrical, chemical and thermal stability. The ablation and optical properties of amorphous PEEK have been investigated using ultrahigh intensity fs laser pulses (180 fs/ 1 kHz) for precision manufacture. The single pulse ablation threshold was found to be 2.01±0.05 J cm-2 and 0.23±0.02 J cm-2 at 775 nm and 387 nm respectively. The significant difference has been attributed to the change in wavelength dependent nonlinear absorption order from multi-photon at 775 nm (via virtual states) to sequential 2-photon at 387 nm with photon energy within the material band edge. The 2-photon absorption coefficient at 387 nm was measured to be β ∼ 38 cm GW-1 at I ∼3 GW cm-2 leading to a strong light-matter coupling. Fs ablation quality is much superior at 387 nm with almost no melting and debris, allowing the observation of laser induced periodic surface structures (LIPSS) with pitch Λ < 0.4 µm. Large area LIPSS have been machined on 200 µm thick amorphous PEEK film with the direction of LIPSS parallel to the direction of linear polarisation.
Original language | English |
---|---|
Journal | Procedia CIRP |
Early online date | 15 Sept 2020 |
DOIs | |
Publication status | E-pub ahead of print - 15 Sept 2020 |