Two-dimensional model for melting and vaporization during optical trepanning

Zeng, D.; Latham, W. P.; Kar, Aravinda

doi:10.1063/1.1897835

Cited by 14 publications

(7 citation statements)

References 20 publications

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“…They assumed that the melt front propagates with an averaged velocity and the averaged melt thickness is determined via dividing the thermal diffusivity of the melt by the averaged propagating velocity [12]. Zeng et al developed a 2-D analytical model for optical trepanning assuming that vaporization rate is negligible [13]. Collins and Gremaud developed a simple 1-D model by cross-section averaging while neglecting the contribution of the radial flow velocity component [14].…”

Section: Introductionmentioning

confidence: 99%

Melt flow and heat transfer in laser drilling

Yang

Chen

Zhang

2016

International Journal of Thermal Sciences

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During the laser drilling process the recoil pressure drives melt flow and affects the heat transfer and material removal rate. To get a more realistic picture of the melt flow, a series of differential equations are formulated here that govern the process from pre-heating to melting and evaporation. In particular, the Navier-Stokes equation governing the melt flow is solved with the use of the boundary layer theory and integral methods. Heat conduction in solid is investigated by using the classical method with the corrections that reflect the change in boundary condition from the constant heat flux to Stefan condition. The dependence of saturation temperature on the vapor pressure is taken into account by using the Clausius-Clapeyron equation. Both constantly rising radial velocity profiles and rising-fall velocity profiles are considered. The proposed approach is compared with existing ones. In spite of the assumed varying velocity profiles, the proposed model predicts that the drilling hole profiles are very close to each other in a specific super alloy for given laser beam intensity and pulse duration. The numerical results show that the effect of melt flow on material removal can be ignored in some cases. The findings obtained from the current work provide a better understanding of the effects of melt flow and vaporization on the laser drilling profile evolution, and could improve the solid material removal efficiency. , melting temperature at solid-liquid interface [K] 0 , saturation temperature at pressure 0 , [K] , saturation temperature at pressure , [K] , pulse on time, [s] , dimensionless radial velocity in the free flow Keywords

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Section: Introductionmentioning

confidence: 99%

Melt flow and heat transfer in laser drilling

Yang

Chen

Zhang

2016

International Journal of Thermal Sciences

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“…The annular beams were used to drill holes with different diameters through a 0.03 mm thick stainless steel foil, known as optical trepanning drilling [15,16]. The laser beam was focused on the upper surface of the stainless steel foil.…”

Section: Processing With Single Annular Beammentioning

confidence: 99%

“…The use of other interesting beam shape can make some specific laser micro-fabrication more flexible. For example, the generation of different sized annular beams can be used to obtain optical trepanning drilling, which is more efficient than the traditional mechanical trepanning drilling [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast laser parallel microdrilling using multiple annular beams generated by a spatial light modulator

Kuang¹,

Perrie²,

Edwardson³

et al. 2014

J. Phys. D: Appl. Phys.

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Ultrafast laser parallel microdrilling using diffractive multiple annular beam patterns is demonstrated in this paper. The annular beam was generated by diffractive axicon computer generated holograms (CGHs) using a spatial light modulator. The diameter of the annular beam can be easily adjusted by varying the radius of the smallest ring in the axicon. Multiple annular beams with arbitrary arrangement and multiple annular beam arrays were generated by superimposing an axicon CGH onto a grating and lenses algorithm calculated multi-beam CGH and a binary Dammann grating CGH, respectively. Microholes were drilled through a 0.03 mm thick stainless steel foil using the multiple annular beams. By avoiding huge laser output attenuation and mechanical annular scanning, the processing is ∼200 times faster than the normal single beam processing.

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“…Noguchi et al 12 applied the enthalpy method to formulate a one-dimensional volumetric heating model and solved it using a finite element technique. Semak et al 15 used a finite difference method, whereas Zeng et al 16 presented an analytic model to calculate the temperature field during laser drilling by considering convective heat transfer due to the liquid metal flow induced by the recoil pressure of the outgoing metal vapor. Semak et al 15 used a finite difference method, whereas Zeng et al 16 presented an analytic model to calculate the temperature field during laser drilling by considering convective heat transfer due to the liquid metal flow induced by the recoil pressure of the outgoing metal vapor.…”

Section: Introductionmentioning

confidence: 99%

A model for self-defocusing in laser drilling of polymeric materials

Zhang

Quick

Kar

2008

Journal of Applied Physics

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A numerical thermal model is presented for laser microvias drilling in multilayer electronic substrates with Nd:YAG ͑YAG denotes yttrium aluminum garnet͒ and CO 2 lasers. Such substrates have different optical properties such as the refractive index and absorption coefficient at these two laser wavelengths, resulting in different drilling mechanisms. Since the skin depth of the polymer is large for both the lasers, volumetric heating is considered in the model. As soon as a small cavity is formed during the drilling process, the concave curvature of the drilling front acts as a concave lens that diverges the incident laser beam. This self-defocusing effect can greatly reduce the drilling speed as predicted by the model. This effect makes the refractive index of the substrate at different wavelengths an important parameter for laser drilling. The model was used to calculate the laser ablation thresholds which were found to be 8 and 56 J / cm 2 for the CO 2 and Nd:YAG lasers respectively. Due to the expulsion of materials because of high internal pressures in the case of Nd:YAG laser microvia drilling, the ablation threshold may be far below the calculated value. A particular laser beam shape, such as pitch fork, was found to drill better holes than the Gaussian beam.

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Two-dimensional model for melting and vaporization during optical trepanning

Cited by 14 publications

References 20 publications

Melt flow and heat transfer in laser drilling

Melt flow and heat transfer in laser drilling

Ultrafast laser parallel microdrilling using multiple annular beams generated by a spatial light modulator

A model for self-defocusing in laser drilling of polymeric materials

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