Effect of process parameters in nanosecond pulsed laser micromachining of PMMA-based microchannels at near-infrared and ultraviolet wavelengths

Abstract

his paper presents investigations on the effects of nanosecond laser processing parameters on depth and width of microchannels fabricated from polymethylmethacrylate (PMMA) polymer. A neodymium-doped yttrium aluminium garnet pulsed laser with a fundamental wavelength of 1,064 nm and a third harmonic wavelength of 355 nm with pulse duration of 5 ns is utilized. Hence, experiments are conducted at near-infrared (NIR) and ultraviolet (UV) wavelengths. The laser processing parameters of pulse energy (402-415 mJ at NIR and 35-73 mJ at UV wavelengths), pulse frequency (8-11 Hz), focal spot size (140-190 μm at NIR and 75 μm at UV wavelengths) and scanning rate (400-800 pulse/mm at NIR and 101-263 pulse/mm at UV wavelengths) are varied to obtain a wide range of fluence and processing rate. Microchannel width and depth profile are measured, and main effects plots are obtained to identify the effects of process parameters on channel geometry (width and depth) and material removal rate. The relationship between process variables (width and depth of laser-ablated microchannels) and process parameters is investigated. It is observed that channel width (140-430 μm at NIR and 100-150 μm at UV wavelengths) and depth (30-120 μm at NIR and 35-75 μm at UV wavelengths) decreased linearly with increasing fluence and increased non-linearly with increasing scanning rate. It is also observed that laser processing at UV wavelength provided more consistent channel profiles at lower fluences due to higher laser absorption of PMMA at this wavelength. Mathematical modeling for predicting microchannel profile was developed and validated with experimental results obtained with pulsed laser micromachining at NIR and UV wavelength

Dross formation and process parameters analysis of fibre laser cutting of stainless steel thin sheets

“…The high repetition rates and the levels of cutting speed used during the experiments result in high overlapping between pulses (98.15-99.44%), calculated as presented in [23] making the assumption of the continuous wave acceptable. The convection and conduction are considered negligible.…”

The influence of organobentonite clay on CO2 laser grooving of nylon 6 composites

“…The above Eq. (12) is true both for continuous wave (CW) laser operation [25], as well as for long pulse quasi-CW operation [7]. In the case of CW laser operation, the depth of the groove is represented as a function of the laser power and scanning speed of the material, while in the Q-CW pulse operation one can use overlap between successive laser pulses O v as a alternative variable for scanning speed V [for a particular pulse repetition rate (PRR)].…”

“…Typically, laser processing of polymers is performed using excimer lasers: 157-355 nm [2], 248 nm [3], 308 nm [4]; solid-state lasers with fundamental or harmonics generation: 395/790 nm [5], 532/1,064 nm [6], 1,064 nm [6,7]; and CO 2 lasers 10.6 μm [4,[8][9][10][11][12]. In terms of the laser pulse duration, both ultra-short (femtosecond [13], and picosecond [14]), as well as long (microsecond) or continuous operation lasers [8][9][10][11][12] can be utilized.…”

“…There are many scientific articles presenting laser processing of various neat polymers (without fillers): for example polytetrafluoroethylene [8,14], polyethylene [5,9,10], polycarbonate [3,[9][10][11], PMMA [3,7,10,11], polyetheretherketone [3,14], as well as fiber-reinforced polymers [12,17], but there is still a lack of information on nylon grooving properties through vaporization by infrared lasers.…”

Effect of Fluence and Pulse Overlapping on Fabrication of Microchannels in PMMA/PDMS Via UV Laser Micromachining: Modeling and Experimentation

“…355 nm or 266 nm). The previous work done by the other researchers including the work by Teixidor et al [19] explored mainly laser micromachining of PMMA and PDMS at NIR wavelength of 1064 nm. However, the UV wavelength light obtained in nanosecond pulsed laser provides additional opportunities to promote photo-chemical ablation and reduces the thermal damage caused by photo-4 thermal ablation.…”