Formation of Surface Microcrack for Separation of Nonmetallic Wafers Into Chips

1999 ◽  
Vol 122 (4) ◽  
pp. 317-322 ◽  
Author(s):  
T. Elperin ◽  
A. Kornilov ◽  
G. Rudin
Keyword(s):  
Laser Beam ◽  
Thermal Stresses ◽  
Theoretical Modeling ◽  
Water Spray ◽  
Electronic Industry ◽  
High Quality ◽  
Thermal Elasticity ◽  
Subsurface Region ◽  
Surface Microcrack

In recent years a technology for a high quality separation of nonmetallic materials into chips using a surface (“blind”) microcrack attracted considerable attention in the electronic industry. In this method a wafer is positioned on the translated X-Y table and is heated by a laser beam up to a temperature of the order of 300–400°C. The wafer is then cooled by an air-water spray, and a surface microcrack is formed due to relaxation of the thermal stresses. The initial microcrack with a depth of the order of several hundred microns then propagates in a subsurface region of a wafer and follows the path of the laser beam. Theoretical modeling based on the solution of the equations of thermal elasticity was performed to determine the distributions of temperature and thermal stresses that cause formation of an “edge” microcrack (at the edge of a wafer) followed by its transformation into a surface microcrack. The results of thermal stresses analysis are in an agreement with experimental observations. [S1043-7398(00)00804-5]

Modelling of Convective Melt Flow and Interface Shape in Commercial Bridgman-Stockbarger Growth of CdZnTe

2000 ◽  
Author(s):  
Toby D. Rule ◽  
Ben Q. Li ◽  
Kelvin G. Lynn
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Solute Transport ◽  
Latent Heat ◽  
Thermal Stresses ◽  
Radiation Detector ◽  
Time History ◽  
High Quality ◽  
Melt Convection ◽  
The Impact

Abstract CdZnTe single crystals for radiation detector and IR substrate applications must be of high quality and controlled purity. The growth of such crystals from a melt is very difficult due to the low thermal conductivity and high latent heat of the material, and the ease with which dislocations, twins and precipitates are introduced during crystal growth. These defects may be related to solute transport phenomena and thermal stresses associated with the solidification process. As a result, production of high quality material requires excellent thermal control during the entire growth process. A comprehensive model is being developed to account for radiation and conduction within the furnace, thermal coupling between the furnace and growth crucible, and finally the thermal stress fields within the growing crystal which result from the thermal conditions imposed on the crucible. As part of this effort, the present work examines the heat transfer and fluid flow within the crucible, using thermal boundary conditions obtained from experimental measurements. The 2-D axisymetric numerical model uses the deforming finite element method, with allowance made for melt convection, solidification with latent heat release and conjugate heat transfer between the solid material and the melt. Results are presented for several stages of growth, including a time-history of the solid-liquid interface (1365 K isotherm). The impact of melt convection, thermal end conditions and furnace temperature gradient on the growth interface is evaluated. Future work will extend the present model to include radiation exchange within the furnace, and a transient analysis for studying solute transport and thermal stress.

Development of 3D Finite Element Model for Predicting Process-Induced Defects in Additive Manufacturing by Selective Laser Melting (SLM)

2016 ◽  
Author(s):  
Bilal Hussain ◽  
A. Sherif El-Gizawy
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Thermal Stresses ◽  
Cost Effective ◽  
Element Model ◽  
Laser Melting ◽  
Two Phase ◽  
Free Process ◽  
Manufacturing Techniques

Selective Laser Melting (SLM) is one of the important Additive Manufacturing techniques for building functional products. Nevertheless, the absence of accurate models for predicting the SLM process behavior, delays development of cost effective and defects free process. This work presents a coupled thermo-mechanical numerical model to capture the two phase (solid-liquid) solidification melting phenomena that occur in the process. The proposed model will also predict the evolvement of process-induced properties and defects particularly residual stresses caused by temperature gradient and thermal stresses. CO2 or Nd:YAG laser beam can be used as a heat source with a Gaussian distribution for the laser beam energy.

Thermal Shock Experiment and Simulation of Ceramic/Metal Gradient Thermal Barrier Coating

2007 ◽  
Vol 336-338 ◽  
pp. 1818-1822
Author(s):  
Jin Sheng Xiao ◽  
Kun Liu ◽  
Wen Hua Zhao ◽  
Wei Biao Fu
Keyword(s):  
Heat Transfer ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Stresses ◽  
Initial Temperature ◽  
Thermal Barrier ◽  
Water Spray ◽  
Barrier Coating ◽  
Shock Experiment ◽  
Two Stages

A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The experiment procedure includes two stages, heating the specimen from the initial temperature 30°C for 40s, and then cooling for 20s. The heat transfer and the associated thermal stresses produced during the thermal shock procedure are simulated by finite element method. Experimental results indicated that the specimen of gradient coating behaves better in thermal shock experiments, which agree with the results of simulation.

scholarly journals APPLICATION OF ADDITIVE TECHNOLOGIES IN MODERN FOUNDRY PRODUCTION

2021 ◽  
Vol 117 (2) ◽  
pp. 20-27
Author(s):  
Zhannur Begendikova ◽  
Amina Bukayeva
Keyword(s):  
Laser Beam ◽  
New Products ◽  
Machine Building ◽  
Global Market ◽  
Model Material ◽  
Additive Technologies ◽  
The Body ◽  
Cad Model ◽  
High Quality ◽  
Building Products

The paper studies and analyzes the use of additive technologies in modern foundry production, determining their innovative development to create new products with high quality, reliability and determining its competitiveness in the world market of machine-building products. The essence of SLS-technology is defined as follows: model material - polystyrene powder with particle size of 50-150 microns - is rolled by a special roller on the working platform installed in a sealed chamber with an inert gas atmosphere - nitrogen. The laser beam "runs" where the computer "sees" the "body" in the given section of the CAD-model, as if "shading" the section of the part, as it is done by the constructor with a pencil on the drawing. In this case the laser beam is a source of heat, under the influence of which sintering of polystyrene particles takes place (working temperature - about 120°С). SLA, Polyjet and DLP technologies are the most widespread for metal casting. The first method involves sequential "running" of the laser beam over the entire surface of the layer to be formed where the model "body" is in the cross section. The second method of curing is performed by a beam in the form of a line in the process of layer formation due to radiation from a controlled ultraviolet lamp. The third way implies illumination of the whole layer simultaneously by creating the so-called mask - a "photo" of the current CAD-model section. Thus, additive technologies in modern foundry production have radically reduced labor intensity and costs of creating new products, which have high quality and reliability indicators and determine their competitiveness in the global market of machine-building products.

Ambient Temperature Temperbead Welding Using the Underwater Laser Beam Welding Process

2010 ◽  
Author(s):  
Bruce Newton
Keyword(s):  
Laser Beam ◽  
Ambient Temperature ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Nuclear Industry ◽  
High Quality ◽  
Gas Tungsten Arc ◽  
Class 1 ◽  
Gtaw Process ◽  
Underwater Laser

Ambient temperature temperbead welding using the Machine Gas Tungsten Arc Welding (GTAW) process is widely accepted in the nuclear industry. GTAW machine ambient temperature temperbead welding, addressed in ASME Code Case N-638, has been used to repair ASME Class 1 components in numerous safety related applications. Underwater laser beam welding (ULBW) is gaining increasing industry recognition as a method for producing high quality welds in high radiation environments. Since ULBW enables high quality weld deposition in underwater environments, the process enables water to serve as a radiation moderator, reducing personnel exposure levels. ULBW’s advantages go beyond radiation exposure reductions, and this paper will provide the reader a better understanding of the ULBW process’s capabilities and properties. A recently formed ASME Task Group is preparing a new Code Case that will delineate specific requirements and essential variables governing use of ULBW to repair ASME Class 1 components. In addition, this Code Case will provide specific rules for use of the ULBW process for ambient temperature temperbead welding. Extensive testing has been performed to demonstrate ULBW’s capabilities with regard to ambient temperature temperbead welding in an underwater environment, and this paper summarizes testing and test results. It also provides a technical summary of the new Code Case, it’s requirements, and summarizes several of the bases for these requirements.

A High-Quality Optical Sound Recording System Using a Scanned Laser Beam

SMPTE Journal ◽  
1980 ◽  
Vol 89 (2) ◽  
pp. 95-97 ◽  
Author(s):  
T. Taneda ◽  
Y. Sugiura ◽  
T. Motoki ◽  
G. Oishi ◽  
H. Miyatera ◽  
...  
Keyword(s):  
Laser Beam ◽  
Recording System ◽  
Sound Recording ◽  
High Quality

Exact laser beam positioning for measurement of vegetation vitality

2017 ◽  
Vol 44 (4) ◽  
pp. 532-541 ◽  
Author(s):  
Lars Lindner ◽  
Oleg Sergiyenko ◽  
Moises Rivas-López ◽  
Daniel Hernández-Balbuena ◽  
Wendy Flores-Fuentes ◽  
...  
Keyword(s):  
Laser Beam ◽  
Unmanned Aerial Vehicle ◽  
Laser Energy ◽  
Vision System ◽  
Field Of View ◽  
Continuous Control ◽  
High Quality ◽  
Content Type ◽  
Dc Motors ◽  
Aerial Vehicle

Purpose The purpose of this paper is to present a novel application for a newly developed Technical Vision System (TVS), which uses a laser scanner and dynamic triangulation, to determine the vitality of agriculture vegetation. This vision system, installed on an unmanned aerial vehicle, shall measure the reflected laser energy and thereby determine the normalized differenced vegetation index. Design/methodology/approach The newly developed TVS shall be installed on the front part of the unmanned aerial vehicle, to perform line-by-line scan in the vision system field-of-view. The TVS uses high-quality DC motors, instead of previously researched low-quality DC motors, to eliminate the existence of two mutually exclusive conditions, for exact positioning of a DC motor shaft. The use of high-quality DC motors reduces the positioning error after control. Findings Present paper emphasizes the exact laser beam positioning in the field-of-view of a TVS. By use of high-quality instead of low-quality DC motors, a significant reduced positioning time was achieved, maintaining the relative angular position error less than 1 per cent. Best results were achieved, by realizing a quasi-continuous control, using a high pulse-width modulated duty cycle resolution and a high execution frequency of the positioning algorithm. Originality/value The originality of present paper is represented by the novel application of the newly developed TVS in the field of agriculture. The vitality of vegetation shall be determined by measuring the reflected laser energy of a scanned agriculture zone. The paper’s main focus is on the exact laser beam positioning within the TVS field-of-view, using high-quality DC motors in closed-loop position control configuration.

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