Excimer laser ablation of polyimide in a manufacturing facility

Lankard, J. R.; Wolbold, Gerhard E.

doi:10.1007/bf00324201

Cited by 90 publications

(30 citation statements)

References 7 publications

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“…As diameter decrease (below 100µm) lasers are preferred over mechanical drills. Since copper is highly reflective thus, Q-switched Nd: YAG lasers (fundamental or 3rd-harmonic) are used to drill the metal, while CO 2 lasers are used to drill the dielectric material.Drilling microvias by ablation was first investigated in the early 1980's using pulsed Nd:YAG and CO 2 lasers [23,24].Excimer lasers led the way in applying it to volume production when the Nixdorf computer plant introduced polyimide ablative drilling of 80µm diameter vias in MCM's -as used to connect silicon chips together in high-speed computers [25].Other mainframe computer manufacturers such as IBM rapidly followed suite and installed their very own production lines for this application [26,27]. With fewer process steps than other methods, laser-drilling is regarded as the most versatile, robust, reliable and high-yield technology for creating microvias in thin film packages.…”

Section: Microvia Hole Drilling In Circuit Intermentioning

confidence: 99%

Laser Beam Micromachining– A Review

2016

Arimpie - 2016

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Abstract-Laser essentially is a coherent, monochromatic beam of electromagnetic radiation that can propagate in a straight line with negligible divergence and occur in a wide range of wavelength (ranging from ultra-violet to infrared). Lasers are widely used in manufacturing, communication, measurement and medical. Energy density of the laser beam can be altered by varying the wavelength. This property has made the lasers proficient for removing extremely small amount of material and has led to the use of lasers to manufacture very small features in work piece materials. The production of miniature features (dimensions from 1 µm to 999 µm) in sheet materials using laser machining is termed as laser micromachining.In the present study, the fundamental understanding of short and ultra-short laser ablation process has been explained. The critical analysis of various theoretical and experimental studies is used to describe the performance of laser beam micromachining (LBMM) on some of the advanced engineering materials.

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Section: Microvia Hole Drilling In Circuit Intermentioning

confidence: 99%

Laser Beam Micromachining– A Review

2016

Arimpie - 2016

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“…Debris can contribute to beam attenuation after ejection but before deposition [5] and can be generated in a mode that coats unimportant areas, areas still to be machined, or, worse still, features that have already been machined [6]. To compound matters, debris can coat machinery, requiring costly downtime for cleaning and servicing [7], or can become airborne in the working environment of tool users, posing potential respiratory health issues [7]. The use of a technique involving closed flowing thick film filtered water immersion of the sample during laser ablation has shown promise as a solution to such problems [9]; however, the impact of such techniques on the basic laser machining characteristics are not extensively documented.…”

Section: Background and Rationalmentioning

confidence: 99%

Excimer Laser Machining of Bisphenol a Polycarbonate under Closed Immersion Filtered Water with Varying Flow Velocities and the Effects on the Etch Rate

Dowding

Lawrence

2010

Proceedings of the Institution of Mechanical Engineers, Part B:

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• This is an article from the journal, Proceedings of the IMechE, Part B: Abstract: Until now, progress in laser ablation micromachining has been significantly limited with respect to feature miniaturization and output yield by ablation-generated debris. Gasjetting techniques have proven to be inadequate and vacuum environments are unwieldy in an industrial setting. To this end, a controlled geometry for both the optical interfaces of a flowing liquid film can be provided by a closed flowing thick film filtered water immersion technique. This ensures repeatable machining conditions and allows control of liquid flow velocity. To investigate the impact of this technique on etch rate, bisphenol A polycarbonate samples have been machined using KrF excimer laser radiation passing through a medium of filtered water flowing at a number of flow velocities that are controllable by modifying liquid flowrate. A mean increase in etch rate of 8.5 per cent when using a turbulent flow velocity regime immersed ablation over ablation in ambient air was recorded. However, use of laminar flow velocities resulted in a mean loss of 26.6 per cent in etch rate compared to ablation in ambient air. Plotting the recorded etch rate achieved with respect to flow velocity gives support for previously proposed flow-plume interactions: the primary cause of a 37 per cent variance in etch rate over a 72 per cent change in laminar flow velocity was a shift in the ratio between the refresh rate of liquid volume over the feature and laser repetition rate. The small variance of etch rate achieved by modification of turbulent regime flow velocity indicates that laser etching provided the dominating contribution to the total etch rate measured. This work demonstrates that this technique developed for ablation debris control does not reduce the efficiency of laser etching with respect to that achieved with established gas media laser ablation machining. Therefore, this process shows great promise for industrial implementation development.

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“…3,4 The impetus for development of laser micromachining has come largely from the electronics industry, where excimer lasers have been used extensively for via drilling in chip packages and printed wiring boards. 5,6 However, excimer lasers have also found applications across a much wider range of industries, covering a variety of materials from polymers to metals and ceramics. 7 Their ability to etch biological materials without collateral damage has also led to a number of surgical applications.…”

Section: Introductionmentioning

confidence: 99%

Excimer laser ablation of microstructures: A numerical model

Paterson

Holmes

Smith

1999

Journal of Applied Physics

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A new model for the ablation of microstructures with excimer laser radiation is presented. The model is based on an interactive two-step approach. The local distribution of the light over the developing structure is evaluated for each pulse. This distribution is then used to calculate the local etch rate, and hence the change to the structure. Despite the assumptions inherent in the model, in particular assumptions made about the propagation of the light through a developing structure and about the etching behavior of the materials, results from the model agree with actual aspects of ablated structures. The model has been used with some success to predict the wall angles of trench structures ablated using partially coherent illumination from a fly's eye homogenizer. Predictions of the model show good agreement with the experiment results. In particular, the model correctly predicts the variation of the wall angles with incident fluence and also predicts structures with well defined wall angles over depths much greater than the depth of focus of the image.

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Excimer laser ablation of polyimide in a manufacturing facility

Cited by 90 publications

References 7 publications

Laser Beam Micromachining– A Review

Laser Beam Micromachining– A Review

Excimer Laser Machining of Bisphenol a Polycarbonate under Closed Immersion Filtered Water with Varying Flow Velocities and the Effects on the Etch Rate

Excimer laser ablation of microstructures: A numerical model

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