ABSTRACTS

The following is a list of the abstracts for papers which will be presented in the 12TH INTERNATIONAL SYMPOSIUM ON PARTICLES ON SURFACES: DETECTION, ADHESION AND REMOVAL. The listing is alphabetical by presenting author. This list is updated continually to add abstracts as they become available and make appropriate corrections. This list may be conveniently searched by using the editor provided with most popular browsers (e.g. Microsoft Explorer, FIREFOX, Netscape, ... etc.)

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Sami B. Awad; Crest Ultrasonics Corp., Scotch Rd., P.O. Box 7266, Trenton, NJ 08628

Effect of Frequency on Particle Shedding from Solid Surfaces

(Abstract not yet available)

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J. Bottomley ^{1 2}, K. Rakos ¹, K. Kendall ² and. Greenwood ²

1) Duont Teijin Films UK Limited, P.O. Box 2002, Wilton, Middlesbrough, TS90 8JF, UK

2) School of Chemical Engineering, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

Application of Atomic Force Microscopy to Barrier Film Defect Analysis

With growing interest from manufacturers in the area of flexible electronics and displays, transparent polymers have become an attractive candidate for both front and back planes in devices.¹ Flexible flat panel display technologies offer many advantages over their rigid glass counterparts, including very thin profiles, exceptionally lightweight, robustness, extreme portability, high throughput manufacturing (roll to roll) and ultimate engineering freedom.²

One of the key requirements of such substrates is a minimum water and oxygen permeability (10^-6 g/m²/day), much lower than most polymeric materials and hence why current flat panel technology utilises substrates such as glass.³ As a result, additional coating layers including metal oxides are required to increase the barrier performance of these films to prevent degradation of Organic Light Emitting Diodes (OLEDs) encapsulated within such devices.¹

The so called ‘calcium test’ was developed as a way of testing the barrier performance of transparent polymer films without using expensive OLED materials.⁴ The test involves deposition of metallic calcium metal onto the barrier film and sealing it onto a glass substrate, this sample is then subjected to accelerated environmental conditions.⁴ Degradation sites can then be observed as transparent areas in the calcium caused by localised permeation of water / oxygen through defects in the barrier and ultimately into the calcium layer.

Barrier layers deposited using current techniques are disrupted by both intrinsic and extrinsic contaminants on the film surface, protruding through the thin film. Locating and analysing these defects is difficult, and methods such as SEM do not allow for absolute measurements of defect edge angles or dimensions.

An Atomic Force Microscope has been used to identify defects located by the calcium test (Figure 1), allowing characterisation of film disruptions and assisting identification of weak point in the manufacturing process. Fluorescent particles have also been used to purposefully contaminate an ultra-clean film with subsequent barrier coating, to allow a comparison of defects caused by known contaminants using the same analysis techniques.

Figure 1: Example defects found on barrier substrates; barrier hole caused by an extrinsic dust particle (left) and an intrinsic contaminant (right), note differences in scale

REFERENCES

1 –    R. Adam, W. A. MacDonald, M. K. Looney, R. Eveson, R. Blisset, C. Thomson, R. Kelly, L. Allan, S. Louch; 2007. The Calcium Test as a Tool for Water-vapor Barrier Evaluation of Flexible Barrier Substrates. Proceedings of Asia Display, 1, P.894-898.

2 –    G. P. Crawford; Flexible Flat Panel Displays. West Sussex, England, J. Wiley & Sons Ltd. Chapter 1, P.1.

3 –    B. A. MacDonald, K. Rollins, D. MacKerron, K. Rakos, R. Eveson, K. Hashimoto, B. Rustin; 2005. Engineered Films for Display Technologies, G. P. Crawford; Flexible Flat Panel Displays. West Sussex, England, J. Wiley & Sons Ltd. Chapter 2, P.23.

4 –    G. L. Graff, R. E. Williford, P. E. Burrows; 2004. Mechanisms of vapour permeation through multilayer barrier films: Lag time versus equilibrium permeation. Journal of Applied Physics, 96 (4), P.1840.

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John Durkee, Precision Cleaning, Hunt, TX 78024

Solvent Wipes for Particle Cleaning

This presentation will cover wipe clean solvents, which are often used to remove particles from surfaces. We will cover why CFC-113 was the “perfect” wipe clean solvent , and why it has been so difficult to replace it with a substitute.

The main theme of the presentation is that compromises are necessary to find a substitute wipe clean solvent. We will identify the parameters essential to choosing a substitute and show how to make the compromise decisions about those parameters which are required to select that substitute.

The role of the solvent, and of the fabric wiper, will both be identified. And the possibility of producing one’s own formulated wipe clean solvent will be discussed.

This presentation is for those who want to learn how to choose a wipe clean solvent to remove particles or other debris from surfaces.

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Deoksuk Jang and Dongsik Kim; Department of Mechanical Engineering, POSTECH, Pohang 790-784, KOREA

Surface Cleaning by Optical Breakdown of Micro Liquid Jet/Droplet

This work presents a novel surface cleaning process using laser-induced breakdown of a micro liquid jet or a micro droplet in the ambient air. In the process, a laser pulse (Q-switched Nd:YAG laser) induces optical breakdown in a small-volume liquid sample (a micro liquid jet or droplet), leading to explosion of the liquid. Plasma expansion following the liquid breakdown produces a shock wave in the ambient air, which is substantially stronger than that generated by air breakdown. Impingement of the shock wave on a solid surface removes submicron particles from the solid surface effectively. Furthermore, if the liquid volume is larger than a critical value, explosion of the liquid accompanies high-speed micro liquid jet from the sample. The high-speed liquid jet can remove particles smaller than 100 nm effectively without surface damage.

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Rajiv Kohli; The Aerospace Corporation, NASA Johnson Space Center, P.O. Box 58128, Houston, TX 77258

The Behavior of Particles at the Nanoscale

Conventional classification of nanoparticles refers to such particles as having a characteristic dimension from 1 to 100 nm with new physical and chemical properties that are not shared by larger, macroscale particles of the same material. In this size range, there is a critical size (~ 30 nm) below which the new properties become evident. The physical nature of such particles cannot be thought of in terms of classical surface or volume continua. Rather, the molecules statistically associated with the particle tend to define their physical and chemical behavior. The behavior of nanoparticles has significant implications for human health and for solutions for mitigating the effects of such particles. These issues will be discussed for some commercial applications.

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Kwang-seok Hwang¹, Inho Kim², and Jin W. Lee²

1) POSCO, Pohang, SOUTH KOREA

2) Dep’t of Mech. Eng., Pohang Univ. of Sci. & Tech., Hyoja 31, Pohang, SOUTH KOREA

Removing 10nm Particles Using the Supersonic Nano Particle Beam

Cryogenic particle beam has proved to be an effective means of removing nano-sized contaminant particles, and the supersonic beam of Ar particles smaller than 100nm was shown to remove ceramic contaminant particles almost completely down to 20nm size.

In this study particle beams of similar properties were used to remove 10nm particles from a flat substrate. Ar, N2, Ar/N₂ and CO₂ particles were generated over a wide range of velocity and particle size from 10nm to 200nm. In order to control the particle size and velocity, generation conditions were varied by a combination of two stagnation temperatures of 100K and 300K and four particle compositions with and without Helium carrier gas.

Removal efficiency for 10nm contaminant particles was sensitive to the choice of combined condition of the beam particle size and velocity. Use of high temperature and He carrier gas facilitated removal. The best removal efficiency obtained for 10nm Al₂O₃ particle was about 90%, which was the best performance reported to date.

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John Lyman; J LYMAN INDUSTRIES INC, 2664 W Eastwood Ave, Chicago IL 60625-2919

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Tack Cloths - Engineered Wipes for Removing Particles from Surfaces

This presentation will cover the following issues related to the use of tack cloths to remove unwanted particle contamination

    * a discussion of What IS Tack Cloth (and what it is NOT); a more detailed discussion of "tack" material systems (hot melt,water borne, etc., common miss perceptions) and similarities to paints, sealants, etc.; some discussion of the "cloth" textile varieties, their general properties and common issues with other wipes.

    * Discussion of how and where tack cloths are used, wiping techniques and common problems, competing technologies.

    * Discussion of product claims (e.g., lint free, antistatic), how tack cloths differ and how to specify and purchase them (e.g., USP standards).

    * Discussion of industry and market trends (e.g., migration of textiles and automotive sectors).New developments in tack cloths (e.g., water-soluble tack).

    * Future trends, opportunities and developing technologies (e.g., waste disposal concerns and “green”technologies)

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Dan Rodier; Particle Measuring Systems, Boulder, Colorado

Measuring Surface Particulate Contamination Levels on Components and Assessing the Effectiveness of Surface Cleaning Methodologies

Achieving clean components requires a consistent cleaning process and a repeatable means of detecting particulate levels. Processing components in aqueous cleaning baths with ultrasonic extraction can be used to remove surface particulate contamination from most components and materials, regardless of their shape or size. The ultrasonic energy can remove particles resting on the surface as well as particles that exhibit a degree of surface adhesion.

An optical particle counter can be used to monitor the cleaning bath while ultrasonic energy is applied to vessel to determine background contamination levels. The component(s) are then placed in the cleaning bath and sonicated for a fixed duration. The particle counts in the cleaning bath are measured and compared to background levels to determine the quantity of contamination originating from the components in the test. Lastly, particle counts in the bath are monitored to determine when background levels have been re-established, indicating the system is ready for the next test.

By processing components through different cleaning methodologies prior to testing, ultrasonic cleaning baths can be used to evaluate the effectiveness of various cleaning techniques. Ultrasonic cleaning systems can also be used to assess the cleanliness of various packaging materials and even cleanroom gloves. This paper presents optimizing ultrasonic cleaning systems and component testing results.

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Revised -- 3/26/2010
URL: http://mstconf.com/particle12-abs.htm