scholarly journals Glass Substrate Dust Removal Using 233 fs Laser-Generated Shockwave

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1382
Author(s):  
Myeongjun Kim ◽  
Philgong Choi ◽  
Jae Heung Jo ◽  
Kyunghan Kim
Keyword(s):  
Glass Substrate ◽  
Pulse Number ◽  
Surface Cleaning ◽  
Dust Particles ◽  
Optimum Number ◽  
Cleaning Efficiency ◽  
Pixel Resolution ◽  
Removal Ratio ◽  
Critical Requirement ◽  
Cleaning Methods

Eliminating dust is gaining importance as a critical requirement in the display panel manufacturing process. The pixel resolution of display panels is increasing rapidly, which means that even small dust particles on the order of a few micrometers can affect them. Conventional surface cleaning methods such as ultrasonic cleaning (USC), CO2 cleaning, and wet cleaning may not be sufficiently efficient, economical, or environment friendly. In this study, a laser shockwave cleaning (LSC) method with a 233 fs pulsed laser was developed, which is different from the laser ablation cleaning method. To minimize thermal damage to the glass substrate, the effect of the number of pulses and the gap distance between the focused laser beam and the glass substrate were studied. The optimum number of pulses and gap distance to prevent damage to the glass substrate was inferred as 500 and 20 μm, respectively. With the optimal pulse number and gap distance, cleaning efficiency was tested at a 95% removal ratio regardless of the density of the particles. The effective cleaning area was measured using the removal ratio map and compared with the theoretical value.

TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites

1991 ◽  
Vol 49 ◽  
pp. 802-803
Author(s):  
C.M. Sung ◽  
M. Levinson ◽  
M. Tabasky ◽  
K. Ostreicher ◽  
B.M. Ditchek
Keyword(s):  
Substrate Surface ◽  
Bulk Sample ◽  
Surface Cleaning ◽  
Native Oxide ◽  
Czochralski Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Cleaning Methods ◽  
Field Emission Cathodes

Directionally solidified Si/TaSi2 eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2 substrates by TEM.Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2 composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2 fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+ until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

Plasma Surface Engineering: An Enabling Technology Designed to Clean and Protect Printed Circuit Boards

2020 ◽  
Vol 2020 (1) ◽  
pp. 000197-000200
Author(s):  
Daphne Pappas ◽  
Sebastian Guist ◽  
Dhia Ben Salem
Keyword(s):  
Organic Contaminants ◽  
Atmospheric Pressure ◽  
Printed Circuit Boards ◽  
Surface Cleaning ◽  
Solvent Free ◽  
Atmospheric Plasma ◽  
Dust Particles ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Surface Contaminants

Abstract Long term reliability and performance of printed circuit boards (PCBs) are strongly affected by the presence of surface contaminants from the manufacturing and assembly processes. Flux and solder residue, dust particles, oils and greases are often found on the assembled boards and can inhibit the successful application of conformal coatings that are used to protect the electronic components. Surface contaminants can cause coating delamination, dendritic growth, electromigration, corrosion and result in compromised coatings. In the first part of this paper, the fundamental mechanism of plasma-induced removal of organic contaminants from PCBs will be presented. While vacuum based plasmas are considered the traditional solvent-free technology for surface cleaning, a new approach involving air plasma operating under atmospheric pressure conditions is gaining interest due to its adaptability for industrial inline processing. The low concentration of oxygen that is available in the plasma gas is effective in vaporizing organic contaminants leaving behind a clean surface. Additionally, atmospheric plasma processes focusing on the development of functional nanocoatings on PCBs have been investigated. These plasma-enhanced chemical vapor deposition (PECVD) processes involve the delivery and vaporization of small volumes of solvent-free precursors that react with the plasma to form thin coatings on polymer substrates. Depending on the chemical structure of the precursor used, adhesion promoting, water repellant or electrical barrier coatings of 30–100nm thickness can be deposited. These protective functional coatings do not require any curing or special handling and no chemical waste is generated. The latest developments in atmospheric pressure PECVD for electronics protection will be presented in the second part of the paper. Besides the improvement of device performance and reliability, the application of PECVD has the potential to replace chemical substances such as primers known to have harmful impact on human health and the environment.

scholarly journals Exploring surface cleaning strategies in hospital to prevent contact transmission of methicillin-resistant Staphylococcus aureus

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Hao Lei ◽  
Rachael M. Jones ◽  
Yuguo Li
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Cleaning ◽  
Hospital Environment ◽  
Route Guidance ◽  
Cleaning Efficiency ◽  
Methicillin Resistant ◽  
Environmental Surfaces ◽  
Susceptible Patient ◽  
Contact Transmission ◽  
Care Worker

Abstract Background Cleaning of environmental surfaces in hospitals is important for the control of methicillin-resistant Staphylococcus aureus (MRSA) and other hospital-acquired infections transmitted by the contact route. Guidance regarding the best approaches for cleaning, however, is limited. Methods In this study, a mathematical model based on ordinary differential equations was constructed to study MRSA concentration dynamics on high-touch and low-touch surfaces, and on the hands and noses of two patients (in two hospitals rooms) and a health care worker in a hypothetical hospital environment. Two cleaning interventions – whole room cleaning and wipe cleaning of touched surfaces – were considered. The performance of the cleaning interventions was indicated by a reduction in MRSA on the nose of a susceptible patient, relative to no intervention. Results Whole room cleaning just before first patient care activities of the day was more effective than whole room cleaning at other times, but even with 100% efficiency, whole room cleaning only reduced the number of MRSA transmitted to the susceptible patient by 54%. Frequent wipe cleaning of touched surfaces was shown to be more effective that whole room cleaning because surfaces are rapidly re-contaminated with MRSA after cleaning. Wipe cleaning high-touch surfaces was more effective than wipe cleaning low-touch surfaces for the same frequency of cleaning. For low wipe cleaning frequency (≤3 times per hour), high-touch surfaces should be targeted, but for high wipe cleaning frequency (>3 times per hour), cleaning should target high- and low-touch surfaces in proportion to the surface touch frequency. This study reproduces the observations from a field study of room cleaning, which provides support for the validity of our findings. Conclusions Daily whole room cleaning, even with 100% cleaning efficiency, provides limited reduction in the number of MRSA transmitted to susceptible patients via the contact route; and should be supplemented with frequent targeted cleaning of high-touch surfaces, such as by a wipe or cloth containing disinfectant.

scholarly journals CFD and Laboratory Studies of Dust Cleaning Efficacy of an Efficient Four Stage Non-Clogging Impingement Filter for Flooded-Bed Dust Scrubbers

2021 ◽  
Author(s):  
Ashish Ranjan Kumar ◽  
Neeraj Gupta ◽  
Steven Schafrik
Keyword(s):  
Laboratory Experiments ◽  
Computer Models ◽  
Dust Particles ◽  
Airflow Rate ◽  
Water Spray ◽  
Laboratory Studies ◽  
Cleaning Efficiency ◽  
Industrial Dust ◽  
Dust Filter ◽  
Cleaning Efficacy

Abstract Fibrous-type filters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods. Dust cleansing systems including flooded-bed dust scrubbers use these mesh-type multi-layered filters. These filters trap dust particles efficiently on their surface and inside their mesh. However, their continued operation leads to dust build-up and subsequent clogging. This results in increased resistance of the filter and lowered airflow rate through the scrubber. This could potentially enhance the exposure of the miners. A non-clogging self-cleaning impingement screen type dust filter was designed by the authors for use in mining and industrial dust cleansing applications. The filter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles. The particles impact one of the impermeable solid metallic filter surfaces and are removed from the airstream. A full cone water spray installed upstream prevents any surface build-up of dust. This paper summaries the computer models generated to show the filter operations and laboratory experiments including optical particle counting to establish the cleaning efficiency.

scholarly journals The Optimal Periodicity of the Gas Transmission Systems Cleaning

2019 ◽  
pp. 85-90
Author(s):  
V. Ya. Hrudz ◽  
N. B. Slobodian
Keyword(s):  
Economic Efficiency ◽  
Transcendental Equation ◽  
Optimal Number ◽  
Gas Pipeline ◽  
Optimum Number ◽  
Hydraulic Efficiency ◽  
Gas Pipelines ◽  
Cleaning Efficiency ◽  
Transmission Systems ◽  
Pipe Line

The technical and economic aspects of improving the hydraulic efficiency of pipeline transmission are considered. Hydraulic efficiency of gas transmission systems reveals directly their economic efficiency and practicability, as well as the process of "aging" of the main gas pipelines over time. One of the effective methods of improving the hydraulic efficiency of a gas pipeline is its periodical cleaning with the use mechanical cleaning units. The process of cleaning gas transmission systems with cleaning pistons is technologically complicated and expensive. Therefore, when planning, it is necessary to create all the conditions that guarantee maximum cleaning efficiency and are costeffective. The increase of the number of gas pipeline cleanings improves the hydraulic effi-ciency of the systems. It increases the profit of gas transmission organizations. As a result, the cost for cleaning goes up and leads to the decrease of profit of the gas transportation companies. Therefore, the number of clean-ings of gas pipelines and gas transmission systems should be equal to the optimum number of cleanings over a period of time. The indices of economic efficiency of gas pipelines pigging are analyzed. The authors find that a more specific indicator of the evaluation of gas pipeline cleaning procedure is the increase in the total profit of the gas transmission company. The dependence of the gas transmission company profit on the number of gas pipe-line cleaning over a certain period of time is investigated. The method of specifying the optimal periodicity of gas transmission systems cleaning is offered. The mathematical model of the process is constructed. On the basis of the model, a transcendental equation for finding the optimal number of gas transportation system cleanings for a certain lifetime is obtained. A grapho-analytical method for the solution of the equation is offered. Based on the calculations, a graphical dependence of the optimal periodicity of gas transmission systems cleaning is constructed.

Real-Time Monitoring of Indium Tin Oxide Laser Ablation in Liquid Crystal Display Patterning

1998 ◽  
Vol 526 ◽  
Author(s):  
M.H. Hong ◽  
Y.F. Lu ◽  
M. Meng ◽  
T.S. Low
Keyword(s):  
Laser Ablation ◽  
Acoustic Wave ◽  
Laser Fluence ◽  
Indium Tin Oxide ◽  
Glass Substrate ◽  
Ablation Threshold ◽  
Liquid Crystal Display ◽  
Pulse Number ◽  
Spectral Lines ◽  
Spectral Intensities

AbstractAudible acoustic wave detection is applied to investigate KrF excimer laser ablation of Indium Tin Oxide (ITO) thin film layer for Liquid Crystal Display (LCD) patterning. It is found that there is no acoustic wave generation if laser fluence is lower than ITO ablation threshold. For laser fluence higher than the threshold, audible acoustic wave will be detected due to shock wave generation during ITO laser ablation. The amplitude of the acoustic wave is closely related to the laser ablation rate. With more laser pulse applied, the amplitude is dropped to zero because the ITO layer is completely removed. However, if laser fluence is increased higher than ablation threshold for glass substrate, the amplitude is also dropped with pulse number but not to zero. It is due to laser ablation of ITO layer and glass substrate at the same time. Since the thickness of ITO layer is in a scale of 100 nm, laser interaction with glass substrate will happen even at the first pulse of high laser fluence irradiation. Laser ablation induced ITO plasma emission spectrum in visible light region is analyzed by an Optical Multi-channel Analyzer (OMA). Specific spectral lines are In I (325.8, 410.2 and 451.1 nm) and In II 591.1 nm. Spectral intensities of 410.2 and 451.1 nm lines are selected to characterize the evolution of ITO plasma intensity with laser fluence and pulse number. It is found that the spectral intensities are reduced to zero with laser pulse number. It is also found that spectral lines other than ITO plasma will appear for laser fluence higher than ablation threshold for glass substrate. Threshold fluences for glass and ITO ablation are estimated for setting up a parameter window to control LCD patterning in real-time.

Experimental Analysis for Low-Temperature Poly-Si Films Produced by Using the Excimer Laser Annealing Method

2006 ◽  
Vol 505-507 ◽  
pp. 277-282 ◽  
Author(s):  
Yu Ru Chen ◽  
Long Sun Chao
Keyword(s):  
Grain Size ◽  
Excimer Laser ◽  
Glass Substrate ◽  
Laser Annealing ◽  
Pulse Number ◽  
Sio2 Layer ◽  
Excimer Laser Annealing ◽  
Melt Pool ◽  
Si Films ◽  
Annealing Method

This paper is to investigate the effects on grain size of different working conditions for making poly Si films by using the excimer laser annealing method. In this research, a KrF excimer laser of 248 nm in wavelength is used to irradiate a-Si films of 0.1 μm in thickness on glass substrate to produce poly-Si ones. The control parameters are laser intensity (200~500 mJ/cm2), pulse number (1~10 shots) and coverage fraction (0~100%). Besides, the effect of a SiO2 layer is also studied, which is utilized as a heat-isolated zone located between the Si film and glass substrate. Average grain sizes from SEM photos are used to analyze the effects of these parameters. Purely from the heat transfer view, the Si film obtains more energy would have the slower cooling or solidification rate, which results in the larger grain. From the experimental results, if the melt pool is within the range of Si film or does not contact its neighboring layer (SiO2 layer or glass substrate), the more absorbed energy from the higher energy intensity, the larger pulse number or the bigger coverage fraction can have the larger average grain size. However, with large enough energy, the melt pool could go through the Si film and touch the lower layer. This would induce much more nuclei due to the homogeneous nucleation in the pool and the heterogeneous nucleation near the interface between the film and the neighboring layer. The resulting grain size is much smaller than that of the former one. The transition points of these two cases for different control parameters can be obtained from the experimental results in this study. When the energy from the laser is small, the SiO2 layer acts like a heat absorber and makes the grain size smaller than that of not having the SiO2 layer. On the other hand, when the energy is large, the SiO2 layer becomes a heat insulator and makes the grain size larger.

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