CO2 Laser Drilling of Microvias Using Diffractive Optics Techniques: I — Mathematical Modeling

2005 ◽  
Author(s):  
Chong Zhang ◽  
Sachin Bet ◽  
Islam A. Salama ◽  
Nathaniel R. Quick ◽  
Aravinda Kar
Keyword(s):  
Mathematical Modeling ◽  
Laser Beam ◽  
Co2 Laser ◽  
Thermal Energy ◽  
Laser System ◽  
Damage Threshold ◽  
Laser Drilling ◽  
Diffractive Optics ◽  
Prototype System ◽  
Drilling Process

This paper is the first of three parts summarizing the research to use diffractive optics at the CO2 laser wavelength to drill microvias in the 40–50 μm range for organic packaging applications. This first part mainly focuses on mathematical modeling of the drilling process, which is used to define the characteristics of the laser beam necessary to achieve the required geometry of the microvias. These laser characteristics and the properties of the incoming laser beam of the CO2 laser system are then used to provide a deterministic approach for obtaining performance data for the diffractive optics design. The targeted optics are designed based on the modeling result and are then integrated into a prototype system to execute the drilling operation. The model is based on the conversion of optical energy into thermal energy due to laser-substrate interaction, propagation of thermal energy in the substrate, thermal as well as radiation damage threshold of the substrate and other important laser drilling parameters (e.g., fluence, temporal and spatial characteristics of the beam, residue at the via bottom).

Theoretical and Experimental Investigation of Laser Drilling in a Partially Transparent Medium

1992 ◽  
Vol 114 (1) ◽  
pp. 71-80 ◽  
Author(s):  
T. Nowak ◽  
R. J. Pryputniewicz
Keyword(s):  
Laser Beam ◽  
Three Dimensional ◽  
Laser Drilling ◽  
Drilling Process ◽  
Transparent Medium ◽  
Finite Sample ◽  
Cross Sectional ◽  
Quantitative Correlation ◽  
Study Results ◽  
Successful Prediction

An investigation of pulsed, laser drilling in a partially transparent medium was conducted. The study included both theoretical and experimental analyses. The theoretical analysis included development of a computer simulation to model the laser drilling process—a three-dimensional finite difference solution with temperature-dependent thermal properties, finite sample geometry, and experimentally determined laser beam characteristics. Both qualitative and quantitative correlation of the theoretical and experimental results was good with successful prediction of hole shapes and minimum error in the theoretically predicted cross-sectional areas of the laser-drilled holes ranging approximately ± three percent over the range of energies per laser pulse considered in this study. Results of calculations and experiments demonstrated the importance of the shape and irradiance distribution of the incident laser beam on the quality of laser-drilled holes in Al2O3 samples.

scholarly journals Laser Drilling Effusion Cooling Holes in Low NOx Turbine Engine Components

1996 ◽  
Author(s):  
Terry L. VanderWert ◽  
Scott A. Litzer ◽  
Loh Wai Meng
Keyword(s):  
Fuel Efficiency ◽  
Laser System ◽  
Major Change ◽  
Laser Drilling ◽  
Drilling Process ◽  
Combustion Chambers ◽  
Turbine Engine ◽  
Minimum Number ◽  
Key Aspects ◽  
Cooling Air

The move to turbine engine designs featuring low NOx emissions and greater fuel efficiency has resulted in a major change in design and manufacture of certain engine parts such as combustion chambers. For example, effusion cooling combustor designs use thousands of 0.5 mm diameter, shallow angle (less than 30 degrees from the surface) holes to provide a film of cooling air over the surface of the combustor. A variety of thermal barrier coatings are also used to protect the surface during operation. Laser drilling is playing a key role in the production of effusion cooling holes. Laser drilling, which uses the focused output of a high power industrial pulsed Nd:YAG laser to trepan the holes, has become the process of choice for producing these because of: - low heat input - rapid drilling rates - ability to drill ceramic coated metals - a minimum number of process variables contributes to reliable, repeatable processes This paper reviews the laser drilling process for producing effusion cooling holes, characteristics of the holes, and developments aimed at increasing the throughput and, therefore, reducing the cost for laser drilling. The paper also summarizes the key aspects of the laser system required to produce combustors that meet airflow and other quality (metallurgical) specifications.

Built-Up Alignment System by Four-Quadrant Detector in High Power Laser System

2013 ◽  
Vol 552 ◽  
pp. 415-419
Author(s):  
Ru Hai Guo ◽  
Kui Shi ◽  
Jun Ma ◽  
Run Qiang Jiang ◽  
Shuai Bei Yu
Keyword(s):  
Laser Beam ◽  
Laser System ◽  
Damage Threshold ◽  
Feedback System ◽  
Alignment Error ◽  
Pointing Error ◽  
Alignment System ◽  
High Laser ◽  
High Power Laser System ◽  
Four Quadrant

Spatial stability is an important property of a laser beam for a laser system. Because four-quadrant detector has more high damage threshold than CCD, it can be applied in a high laser system to monitor the direction of laser beam. In this article, the four-quadrant detector as pointing monitor device is used for a 532nm semiconductor laser, which can obtain the center position of laser spot quickly. In the experiment, the amount of shift and jitter for laser beam is measured at first. Next step is combining rotating stage and lens to measure the alignment error for three angles. The results show that the top amount of shift and jitter is 3.6″ and the average of combined pointing error is around 6″. The data can support the spatial beam pointing stability system which needs feedback system with fast steering mirrors.

Heat Absorbing Rate in Laser Drilling of YG8 Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 4164-4167
Author(s):  
Xu Yue Wang ◽  
Wen Ji Xu ◽  
Lian Ji Wang ◽  
Jun Wang ◽  
Yan De Liang
Keyword(s):  
Laser Beam ◽  
Laser System ◽  
Laser Drilling ◽  
The Novel ◽  
Spatial Mode ◽  
Drilling Temperature ◽  
Research Outcome ◽  
Novel Method ◽  
Relationship Of ◽  
The Relationship

Based on a principle of laser drilling size and the roundness copied with respect of laser spatial mode, heat absorbing rate for laser drilling of YG8 is presented in theory and application. The mathematical models are then developed. The relationship of heat absorbing rate compared to the original absorbing rate is thus derived that is A = T +A0. It shows that heat absorbing rate to laser beam increases linearly with drilling temperature. The research outcome is used to optimize preheating process in which the novel method improves laser drilling precision from 0.03mm of primitive laser system to 0.01mm under the condition of heat absorbing.

Microstructure fabrication with a CO2 laser system: characterization and fabrication of cavities produced by raster scanning of the laser beam

Lab on a Chip ◽  
2003 ◽  
Vol 3 (4) ◽  
pp. 302 ◽  
Author(s):  
Martin F. Jensen ◽  
Mikkel Noerholm ◽  
Leif H�jslet Christensen ◽  
Oliver Geschke
Keyword(s):  
Laser Beam ◽  
Co2 Laser ◽  
Laser System ◽  
Raster Scanning ◽  
Microstructure Fabrication ◽  
System Characterization

scholarly journals Effects of Beam Size and Pulse Duration on the Laser Drilling Process

2016 ◽  
Author(s):  
Nazia Afrin ◽  
Pengfei Ji ◽  
J. K. Chen ◽  
Yuwen Zhang
Keyword(s):  
Laser Beam ◽  
Pulse Duration ◽  
Material Removal ◽  
Convection Heat Transfer ◽  
Laser Drilling ◽  
Drilling Process ◽  
Beam Diameter ◽  
Beam Size ◽  
Laser Beam Diameter ◽  
Ablation Efficiency

A two-dimensional axisymmetric transient laser drilling model is used to analyze the effects of laser beam diameter and laser pulse duration on the laser drilling process. The model includes conduction and convection heat transfer, melting, solidification and vaporization, as well as material removal resulting from the vaporization and melt ejection. The validated model is applied to study the effects of laser beam size and pulse duration on the geometry of the drilled hole. It is found that the ablation effect decrease with the increasing beam diameter due to the effect of increased vaporization rate, and deeper hole is observed for the larger pulse width due to the higher thermal ablation efficiency.

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