Modeling of solid-state and excimer laser processes for 3D micromachining

Holmes, Andrew S.; Onischenko, A.; George, David J.; Pedder, J. E. A.

doi:10.1117/12.600632

Cited by 5 publications

(6 citation statements)

References 14 publications

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“…Ignoring the workpiece greatly simplifies the calculation, while at the same time limiting the range of situations to which the simulator can be applied. Details of the calculation, which takes full account of the illumination optics, can be found in earlier publications [9,11].…”

Section: Multi-pulse Ablation Simulatormentioning

confidence: 99%

“…Both the cost of mask manufacture and the delay caused by iterative corrections to the mask design can be a problem for many potential users of laser ablation. We have previously reported on the development of simulation tools to aid in the design of laser tool paths and photomasks [9][10][11]. These tools can reduce the need for iterative corrections and reduce the overall cost of producing a prototype structure.…”

Section: Introductionmentioning

confidence: 99%

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A study of angular dependence in the ablation rate of polymers by nanosecond pulses

Pedder

Holmes

2006

Photon Processing in Microelectronics and Photonics V

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Measurements of ablation rate have traditionally been carried out only at normal incidence. However, in real-world applications ablation is often carried out at oblique angles, and it is useful to have prior knowledge of the ablation rate in this case. Detailed information about the angular dependence is also important for the development of ablation simulation tools, and can provide additional insight into the ablation mechanism. Previously we have reported on the angular dependence of direct-write ablation at 266 nm wavelength in solgel and polymer materials. In this paper we present a systematic study of angular dependence for excimer laser ablation of two polymer materials of interest for microfabrication: polycarbonate and SU8 photoresist. The results are used to improve simulation models to aid in mask design.

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Section: Multi-pulse Ablation Simulatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A study of angular dependence in the ablation rate of polymers by nanosecond pulses

Pedder

Holmes

2006

Photon Processing in Microelectronics and Photonics V

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“…This approach has difficulties in accounting for the interaction between two consecutive pulses such as preheating [18,27], surface property modification [28], material ejection [18] that are present during nanosecond ablation with a high level of overlapping and rapid repetition rate of the pulses. Generally, a high level of overlapping of the pulses is used to obtain a machined surface with a low roughness; therefore, the pulse-topulse description is not the best method to predict accurately the workpiece micro-topography in real-life machining [25,26].…”

Section: Introductionmentioning

confidence: 99%

“…From these families of modelling frameworks, the model that relies on empirical calibration seems to be the one that gives better results and high ver- satility; however it cannot accurately simulate large scale machining [25,26].…”

Section: Introductionmentioning

confidence: 99%

“…These approaches encompass modelling (i) based upon simplified assumptions such as rectangular temporal profile of the laser pulse [19], constant material properties over a large temperature range [20], material removal over a defined temperature/energy [21] which does not provide good accuracy for the profile of the trench and might still require significant computing power; (ii) based on artificial intelligence methods (neural network, genetic algorithms, etc.) [22,23,24], that require a significant set of data for training the algorithm, are not able to capture the details of the physics of the process, work only within the range in which they have been trained and cannot be modified to capture experimental observation of overlapped pulses; (iii) based on empirical calibration [1,25,26] that describe the interaction between the workpiece and one pulse from the laser by fitting the result from experimental data; the main drawback of this method is the loss of accuracy during overlapping of pulses [25,26].…”

Section: Introductionmentioning

confidence: 99%

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Continuous trench, pulsed laser ablation for micro-machining applications

Cadot

Axinte

Billingham

2016

International Journal of Machine Tools and Manufacture

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The generation of controlled 3D micro-features by pulsed laser ablation in various materials requires an understanding of the material's temporal and energetic response to the laser beam. The key enabler of pulsed laser ablation for micro-machining is the prediction of the removal rate of the target material, thus allowing real-life machining to be simulated mathematically.Usually, the modelling of micro-machining by pulsed laser ablation is done using a pulse-by-pulse evaluation of the surface modification, which could lead to inaccuracies when pulses overlap.To address these issues, a novel continuous evaluation of the surface modification that use trenches as a basic feature is presented in this paper. The work investigates the accuracy of this innovative continuous modelling framework for micro-machining tasks on several materials. The model is calibrated using a very limited number of trenches produced for a range of powers and feed speeds; it is then able to predict the change in topography with a size comparable to the laser beam spot that arises from essentially arbitrary toolpaths. The validity of the model has been proven by being able to predict the surface obtained from single trenches with constant feed speed, single 1 trenches with variable feed speed and overlapped trenches with constant feed speed for three different materials (graphite, polycrystalline diamond and a metal-matrix diamond CMX850) with low error. For the three materials tested, it is found that the average error in the model prediction for a single trench at constant feed speed is lower than 5 % and for overlapped trenches the error is always lower than 10 %. This innovative modelling framework opens avenues to: (i) generate in a repeatable and predictable manner any desired workpiece micro-topography; (ii) understand the pulsed laser ablation machining process, in respect of the geometry of the trench produced, therefore improving the geometry of the resulting parts; (iii) enable numerical optimisation for the beam path, thus supporting the development of accurate and flexible computer assisted machining software for pulsed laser ablation micro-machining applications.

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