1、Designation:E209006 Designation: E2090 12Standard Test Method forSize-Differentiated Counting of Particles and FibersReleased from Cleanroom Wipers Using Optical andScanning Electron Microscopy1This standard is issued under the fixed designation E2090; the number immediately following the designatio
2、n indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONTechniques for determining the numbe
3、r of particles and fibers that can potentially be released fromwiping materials consist of two steps. The first step is to separate the particles and fibers from thewiper and capture them in a suitable medium for counting, and the second step is to quantify thenumber and size of the released particl
4、es and fibers.The procedure used in this test method to separate particles and fibers from the body of the wiperis designed to simulate conditions that the wiper would experience during typical use. Therefore, thewiper is immersed in a standard low-surface-tension cleaning liquid (such as a surfacta
5、nt/watersolution or isopropyl alcohol/water solution) and then subjected to mechanical agitation in that liquid.The application of moderate mechanical energy to a wiper immersed in a cleaning solution is effectivein removing most of the particles that would be released from a wiper during typical cl
6、eanroomwiping. This test method assumes the wiper is not damaged by chemical or mechanical activity duringthe test.Once the particles have been released from the wiper into the cleaning solution, they can becollected and counted. The collection of the particles is accomplished through filtration of
7、theparticle-laden test liquid onto a microporous membrane filter. The filter is then examined using bothoptical and scanning electron microscopy where particles are analyzed and counted. Microscopy waschosen over automated liquid particle counters for greater accuracy in counting as well as formorph
8、ological identification of the particles.The comprehensive nature of this technique involves the use of a scanning electron microscope(SEM) to count particles distributed on a microporous membrane filter and a stereo-binocular opticalmicroscope to count large fibers. Computer-based image analysis an
9、d counting is used for fields wherethe particle density is too great to be accurately determined by manual counting.Instead of sampling aliquots, the entire amount of liquid containing the particles and fibers insuspension is filtered through a microporous membrane filter. The filtering technique is
10、 crucial to theprocedure for counting particles. Because only a small portion of the filter will actually be counted,the filtration must produce a random and uniform distribution of particles on the filter. After filtration,the filter is mounted on an SEM stub and examined using the optical microsco
11、pe for uniformity ofdistribution. Large fibers are also counted during this step. Once uniformity is determined and largefibers are counted, the sample stub is transferred to the SEM and examined for particles.Astatisticallyvalid procedure for counting is described in this test method. The accuracy
12、and precision of theresultant count can likewise be measured.This test method offers the advantage of a single sample preparation for the counting of bothparticles and fibers. It also adds the capability of computerized image analysis, which providesaccurate recognition and sizing of particles and f
13、ibers. Using different magnifications, particles from0.5 to 1000 m or larger can be counted and classified by size. This procedure categorizes three classesof particles and fibers: small particles between 0.5 and 5 m; large particles greater than 5 m but1This test method is under the jurisdiction of
14、 ASTM Committee E21 on Space Simulation and Applications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Nov.April 1, 2006.2012. Published December 2006.May 2012. Originally approved in 2000. Last previous edition approved in 20002
15、006 asE2090 - 006. DOI: 10.1520/E2090-06.10.1520/E2090-12.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all chang
16、es accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Uni
17、ted States.smaller than 100 m; and large particles and fibers equal to or greater than 100 m. The technique asdescribed in this test method uses optical microscopy to count large particles and fibers greater than100 m and SEM to count the other two classes of particles. However, optical microscopy c
18、an beemployed as a substitute for SEM to count the large particles between 5 and 100 m2.1. Scope1.1 This test method covers testing all wipers used in cleanrooms and other controlled environments for characteristics relatedto particulate cleanliness.1.2 This test method includes the use of computer-
19、based image analysis and counting hardware and software for the countingof densely particle-laden filters (see 7.7-7.9). While the use of this equipment is not absolutely necessary, it is stronglyrecommended to enhance the accuracy, speed, and consistency of counting.1.3 The values stated in SI unit
20、s are to be regarded as the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimit
21、ations prior to use.2. Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterF25 Test Method for Sizing and Counting Airborne Particulate Contamination in Cleanrooms and Other Dust-Controlled AreasF312 Test Methods for Microscopical Sizing and Counting Particles from Aerospace
22、 Fluids on Membrane Filters2.2 Other Documents:ISO 14644-1 Cleanrooms and Associated Controlled Environments Classification of Air Cleanliness4ISO 14644-2 Cleanrooms and Associated Controlled Environments Part 2: Specifications for testing and monitoring to provecontinued compliance with ISO 14644-1
23、4Fed. Std. 209E Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones53. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 automatic counting, ncounting and sizing performed using computerized image analysis software.3.1.2 cleanroom wiper, na piece of absorbent kni
24、t, woven, nonwoven, or foam material used in a cleanroom for wiping, spillpickup, or applying a liquid to a surface.3.1.2.1 DiscussionCharacteristically, these wipers possess very small amounts of particulate and ionic contaminants and areprimarily used in cleanrooms in the semiconductor, data stora
25、ge, pharmaceutical, biotechnology, aerospace, and automotiveindustries.3.1.3 effective filter area, nthe area of the membrane which entraps the particles to be counted.3.1.4 fiber, na particle having a length to diameter ratio of 10 or greater.3.1.5 illuminance, nluminous flux incident per unit of a
26、rea.3.1.6 particle, na unit of matter with observable length, width, and thickness.3.1.7 particle size, nthe size of a particle as defined by its longest dimension on any axis.4. Summary of Test Method4.1 Summary of Counting MethodsSee the following:Counting Technique Particle Size Range100 m 5100 m
27、 0.55 mStereobinocular optical microscope 203manualANABScanning electron microscope NA 2003 auto 30003 manualor automaticBASee Footnote 2.BNA = not applicable.2The counting of particles 5 to 100 m by optical microscopy is not described in this test method. However, procedures for counting particles
28、in this size range aredescribed in the Test Methods F25 and F312.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM we
29、bsite.4Available from American National Standards Institute, 11 W. 42nd St., 13th Floor, New York, NY 10036.4Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.5Cancelled Nov. 29, 2001 and replaced with ISO 14644-1 and ISO 1
30、4644-2, FED-STD-209E may be used by mutual agreement between buyer and seller. Available fromU.S. Government Printing Office,Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.E2090 1225. Significance and Use5.1 This test method
31、 provides for accurate and reproducible enumeration of particles and fibers released from a wiper immersedin a cleaning solution with moderate mechanical stress applied. When performed correctly, this counting test method is sensitiveenough to quantify very low levels of total particle and fiber bur
32、den. The results are accurate and not influenced by artifact orparticle size limitations. A further advantage to this technique is that it allows for morphological as well as X-ray analysis ofindividual particles.6. Apparatus6.1 Scanning Electron Microscope , with high-quality imaging and computeriz
33、ed stage/specimen mapping capability.6.2 Stereo-Binocular Optical Microscope, with at least 403-magnification capability equipped with a two-arm, adjustable-anglevariable-intensity light source and a specimen holding plate.6.3 Orbital Shaker, that provides 20-mm (34-in.) diameter circular motion in
34、a horizontal plane at 150 r/min.6.4 Microanalytical Stainless Steel Screen-Supported Membrane Filtration Apparatus, with stainless steel funnel, TFE-fluorocarbon gasket and spring clamp.6.5 Vacuum Pump, capable of providing a pressure of 6.5 kPa (65 mb) (49 torr) or lower.6.6 Cold Sputter/Etch Unit,
35、 with gold or gold/palladium foils.6.7 Video Camera (3-CCD preferable), that can be attached to the stereo-binocular microscope and a monitor to provide videomicroscopy capability.6.8 Personal Computer (486-Type Processor or Better) and Monitor.6.9 Frame-Grabbing Hardware and Image Analysis Software
36、, compatible with the personal computer.66.10 Hand-Operated Tally Counter.6.11 Stage Micrometer, with 0.1- and 0.01-mm subdivisions.6.12 Horizontal, Unidirectional Flow Workstation, with ISO Class 5 (Fed. Std. 209 Class 100) or cleaner air.7. Materials7.1 Deionized Water, in accordance with Specific
37、ation D1193, Type III, 4.0 3 106(V-cm)1or better.7.2 Cleanroom Gloves (for example, unpowdered latex gloves).7.3 Fine-Point, Duckbill Tweezers.7.4 Forceps, two pairs, with flat gripping surface tips.7.5 Glass Beakers, 1.5 L, cleaned in accordance with 10.2.1.7.6 Polyethylene Photographic Tray, appro
38、ximately 250 by 340 by 45 mm cleaned in accordance with 10.2.1.7.7 Polycarbonate Membrane Filters (typically 0.1- to 0.4-m pore size), white, and 25-mm diameter.7.8 Petri Slide,47mm.7.9 SEM Aluminum Specimen Stubs, typically 32-mm diameter by 10-mm height.7.10 Polystyrene Latex Microspheres (sizes 0
39、.5 and 5 m) for use in calibration (see Section 9).7.11 Carbon Paint, for SEM stub preparation.7.12 Low-Surface-Tension Cleaning LiquidAny 8- to 10-mole ethoxylated-octyl- or nonyl-phenol-type surfactant7preparedas a 0.1 % stock solution in deionized water. This solution will facilitate the release
40、of both nonpolar and polar contaminants andcan serve as a general test standard across industries. However, this test method is not limited to a specific cleaning solution andonly requires that the cleaning liquid used be relatively free of particles and fibers. It is recommended that the cleaning l
41、iquid mostrelevant to the product end use be considered for this test method.8. Preparation of Apparatus8.1 Setting Up Stereo-Binocular Optical MicroscopeSee Section 10.8.2 Fiber Counting by Optical MicroscopySee Section 10.8.3 Setting Up Scanning Electron Microscope (SEM)See Section 10.8.4 Particle
42、 Counting by SEMSee Section 10.9. Calibration and Standardization9.1 For the fiber counting by optical microscopy, the size calibration at 203 magnification can be done by comparing the fibersizes, as visualized in the video monitor, with the rulings on the stage micrometer (with 0.1- and 0.01-mm su
43、bdivisions). For the6“Image-Pro Plus,” Version 3.0,7, available from Media Cybernetics, has been found to be satisfactory for this test method.The sole source of supply of the apparatus known to the committee at this time is Media Cybernetics. If you are aware of alternative suppliers, please provid
44、e thisinformation to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you mayattend.7Tritont X-100 manufactured by Rohm and Haas Co. has been found to be satisfactory for this test method.The sole source of s
45、upply of the apparatus known to the committee at this time is Rohm and Haas Co. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which yo
46、u mayattend.E2090 123equipment described above, a linear dimension of 8 mm in the video screen equaled 100 m. The conversion factors areequipment-dependent and users of this test method shall establish the relation between screen size and object size.9.2 In the SEM study, to determine the values of
47、the start and the end areas for the computer-assisted automatic particlecounting, it is necessary to perform the size calibration study by experimenting with standard-sized particles such as polystyrenemicrospheres or actual particles of known dimensions which can be ascertained by using the microme
48、tre bar measurement toolavailable on most SEMs.9.3 To prepare a stub with 0.5- and 5-m spheres, add 10 L of each of the 0.5- and 5-m sphere suspensions to a beakercontaining 500 mL of deionized water.9.4 Filter the solution using a new membrane filter.9.5 Prepare the SEM stub. Save the stub in a cle
49、an container as a standard size reference for the automatic particle countingat 200 and at 30003.9.6 For the manual procedure at 30003, avoid counting particles having approximate linear lengths of 25 mm and up, as thosewill have sizes larger than 5 m as determined from measurements done against the micrometre bars at various magnifications inthe SEM.10. Procedure10.1 The procedure consists of two parts: preparing the sample and counting the fibers and particles. Fibers and particles greaterthan 100 m are counted using an optical microsco
