EN ISO 14644-9:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Reinräume und zugehörige Reinraumbereiche - Teil 9: Klassifzierung der partikulären Oberflächenreinheit (ISO 14644-9:2012)Salles propres et environnements maîtrisés apparentés - Partie 9: Classification de la propreté des surfaces par la concentration de particules (ISO 14644-9:2012)Cleanrooms and associated controlled environments - Part 9: Classification of surface cleanliness by particle concentration (ISO 14644-9:2012)13.040.35Brezprašni prostori in povezana nadzorovana okoljaCleanrooms and associated controlled environmentsICS:Ta slovenski standard je istoveten z:EN ISO 14644-9:2012SIST EN ISO 14644-9:2012en,fr01-oktober-2012SIST EN ISO 14644-9:2012SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN ISO 14644-9
August 2012 ICS 13.040.35 English Version
Cleanrooms and associated controlled environments - Part 9: Classification of surface cleanliness by particle concentration (ISO 14644-9:2012)
Salles propres et environnements maîtrisés apparentés - Partie 9: Classification de la propreté des surfaces par la concentration de particules (ISO 14644-9:2012)
Reinräume und zugehörige Reinraumbereiche - Teil 9: Klassifzierung der partikulären Oberflächenreinheit (ISO 14644-9:2012) This European Standard was approved by CEN on 14 August 2012.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
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Reference numberISO 14644-9:2012(E)© ISO 2012
INTERNATIONAL STANDARD ISO14644-9First edition2012-08-15Cleanrooms and associated controlled environments — Part 9: Classification of surface cleanliness by particle concentration Salles propres et environnements maîtrisés apparentés — Partie 9: Classification de la propreté des surfaces par la concentration de particules
ISO 14644-9:2012(E)
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ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56  CH-1211 Geneva 20 Tel.
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ISO 14644-9:2012(E) © ISO 2012 – All rights reserved iii Contents Page Foreword . iv Introduction . v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 1 4 Abbreviated terms . 2 5 Classification system . 3 5.1 ISO-SCP classification format . 3 5.2 Designation . 6 5.3 General information on surface cleanliness by particle concentration . 6 6 Demonstration of compliance . 6 6.1 Principle . 6 6.2 Testing . 6 6.3 Test report . 7 Annex A (informative)
Surface characteristics . 9 Annex B (informative)
Descriptor for specific particle size ranges . 12 Annex C (informative)
Parameters influencing the SCP classification . 15 Annex D (informative)
Measurement methods for determining surface cleanliness by particle concentration . 17 Bibliography . 25
ISO 14644-9:2012(E) iv © ISO 2012 – All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14644-9 was prepared by Technical Committee ISO/TC 209, Cleanrooms and associated controlled environments. ISO 14644 consists of the following parts, under the general title Cleanrooms and associated controlled environments:  Part 1: Classification of air cleanliness  Part 2: Specifications for monitoring to prove continued compliance with ISO 14644-1  Part 3: Test methods  Part 4: Design, construction and start-up  Part 5: Operations  Part 6: Vocabulary  Part 7: Separative devices (clean air hoods, gloveboxes, isolators, and mini-environments)  Part 8: Classification of air cleanliness by chemical concentration  Part 9: Classification of surface cleanliness by particle concentration  Part 10: Classification of surface cleanliness by chemical concentration Attention is also drawn to ISO 14698, Cleanrooms and associated controlled environments — Biocontamination control:  Part 1: General principles and methods  Part 2: Evaluation and interpretation of biocontamination data SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) © ISO 2012 – All rights reserved v Introduction Cleanrooms and associated controlled environments provide for the control of contamination to levels appropriate for accomplishing contamination-sensitive activities. Products and processes that benefit from the control of contamination include those in such industries as aerospace, microelectronics, optics, nuclear, and life sciences (pharmaceuticals, medical devices, food, healthcare). ISO 14644-1 to ISO 14644-8 and ISO 14698-1 and ISO 14698-2 (biological contamination) deal exclusively with airborne particle and chemical contamination. Many factors, besides the classification of surface cleanliness, should be considered in the design, specification, operation and control of cleanrooms and other controlled environments. These factors are covered in some detail in other parts of ISO 14644 and ISO 14698. This part of ISO 14644 provides a classification for the determination and designation of surface cleanliness levels based on particle concentrations. This part of ISO 14644 also lists some methods of testing, as well as procedure(s) for determining the concentration of particles on surfaces. Where regulatory agencies impose supplementary guidelines or restrictions, appropriate adaptations of the testing procedures might be required.
INTERNATIONAL STANDARD ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 1 Cleanrooms and associated controlled environments — Part 9: Classification of surface cleanliness by particle concentration 1 Scope This part of ISO 14644 establishes the classification of cleanliness levels on solid surfaces by particle concentration in cleanrooms and associated controlled environment applications. Recommendations on testing and measuring methods, as well as information about surface characteristics, are given in Annexes A to D. This part of ISO 14644 applies to all solid surfaces in cleanrooms and associated controlled environments, such as walls, ceilings, floors, working environments, tools, equipment and products. The classification of surface cleanliness by particle concentration (SCP) is limited to particles between 0,05 µm and 500 µm. The following issues are not considered in this part of ISO 14644:  requirements for the cleanliness and suitability of surfaces for specific processes;  procedures for the cleaning of surfaces;  material characteristics;  references to interactive bonding forces or generation processes that are usually time-dependent and process-dependent;  selection and use of statistical methods for classification and testing;  other characteristics of particles, such as electrostatic charge, ionic charges, microbiological state, etc. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14644-6:2007, Cleanrooms and associated controlled environments — Part 6: Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 14644-6:2007 and the following apply. 3.1 descriptor for specific particle size ranges differential descriptor that expresses SCP level within specific particle size ranges SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 2 © ISO 2012 – All rights reserved NOTE The descriptor may be applied to particle size ranges of special interest or those particle size ranges that are outside the range of the classification system, and specified independently or as a supplement to the SCP classes. 3.2 direct measurement method assessment of the contamination without any intermediate steps 3.3 indirect measurement method assessment of the contamination with intermediate steps 3.4 solid surface boundary between the solid and a second phase 3.5 surface particle solid and/or liquid matter adhered and discretely distributed on a surface of interest, excluding film-like matter that covers the whole surface NOTE Surface particles are adhered via chemical and/or physical interactions. 3.6 surface cleanliness by particle concentration SCP condition of a surface with respect to its particle concentration NOTE The surface cleanliness depends upon material and design characteristics, stress loads (complexity of loads acting on a surface) and prevailing environmental conditions, along with other factors. 3.7 surface cleanliness by particle concentration class SCP class grading number stating the maximum allowable surface concentration, in particles per square metre, for a considered size of particles (SCP Classes 1 to 8) 3.8 surface cleanliness by particle concentration classification SCP classification level (or the process of specifying or determining the level) that represents maximum allowable surface concentrations, in particles per square metre, for considered sizes of particles, expressed in terms of an ISO SCP Class N 3.9 surface particle concentration number of individual particles per unit of surface area under consideration 4 Abbreviated terms For the purposes of this document, the following abbreviated terms apply. AFM atomic force microscopy CNC condensation nucleus counter EDX energy dispersive X-ray spectroscopy ESCA electron spectroscopy for chemical analysis ESD electrostatic discharge SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 3 IR infrared (absorption spectroscopy) OPC optical particle counter PET polyethylene terephthalate SCP surface cleanliness by particle concentration SEM scanning electron microscopy UV ultraviolet (spectroscopy) WDX wavelength-dispersive X-ray spectroscopy 5 Classification system 5.1 ISO-SCP classification format The class of surface cleanliness by particle concentration (SCP) in a cleanroom or associated controlled environment shall be designated by a classification number, N, specifying the maximum total particle concentration on surfaces permitted for a considered particle size. N shall be determined from the following equation with the maximum permitted total particle concentration on the surface, CSCP;D, in particles per square metre of surface, for each considered particle size, D: SCP;D10NCkD (1) where CSCP;D is the maximum permitted total surface concentration, in particles per square metre of surface, of particles that are equal to or larger than the considered particle size; CSCP;D is rounded to the nearest whole number, using no more than three significant figures; N is the SCP classification number, which is limited to SCP Class 1 through SCP Class 8; SCP Class number N is represented by the measured particle diameter D, in micrometres; NOTE N refers to the exponent base 10 for the concentration of particles at the reference particle size of 1 µm. D is the considered particle size, in micrometres. k is a constant 1, in micrometres. NOTE 1 The SCP class based on the particle concentration can be a time- and process-dependent value due to the dynamic characteristics of particle generation and transportation. NOTE 2 Due to the complexity of statistical evaluations and readily available additional references, the selection and use of statistical methods for classification and testing are not described in this part of ISO 14644. The concentration CSCP;D, as derived from Equation (1), shall serve as the definitive value. Table 1 presents selected SCP classes and corresponding maximum cumulative permitted total surface concentrations for considered particle sizes. Figure 1 provides a representation of the selected classes in graphical form. SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 4 © ISO 2012 – All rights reserved Table 1 — Selected SCP classes for cleanrooms and associated controlled environments Units in particles per square metre SCP Class Particle size R 0,05 µm R 0,1 µm R 0,5 µm R 1 µm R 5 µm R 10 µm R 50 µm R 100 µm R 500 µmSCP Class 1 (200) 100 20 (10)
SCP Class 2 (2 000) 1 000 200 100 (20) (10)
SCP Class 3 (20 000) 10 000 2 000 1 000 (200) (100)
SCP Class 4 (200 000) 100 000 20 000 10 000 2 000 1 000 (200) (100)
SCP Class 5
1 000 000200 000 100 000 20 000 10 000 2 000 1 000 (200) SCP Class 6
(10 000 000)2 000 000 1 000 000 200 000 100 000 20 000 10 000 2 000 SCP Class 7
10 000 0002 000 0001 000 000 200 000 100 000 20 000 SCP Class 8
10 000 0002 000 000 1 000 000 200 000 The values in Table 1 are concentrations of particles of the related particle size and SCP class per surface area of one square metre (1 m2) equal to or larger than the considered particle size (CSCP;D). For figures in parentheses, the corresponding particle sizes should not be used for classification purposes; select another particle size for classification. The minimum area for testing should be statistically representative of the surface under consideration. NOTE Classification of the lower SCP classes requires numerous measurements to establish a significant value.
ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 5
Key X considered particle size, D (µm) Y particle concentration on a surface ≥ D, CSCP;D (particles/m2) 1 SCP Class 1 2 SCP Class 2 3 SCP Class 3 4 SCP Class 4 5 SCP Class 5 6 SCP Class 6 7 SCP Class 7 8 SCP Class 8 The solid classification lines shown on the graph shall be used for classification purposes. The dashed lines should not be used for classification purposes. NOTE Particle distribution on surfaces typically is not a normal distribution, but is affected by different factors, such as roughness, porosity, electrostatic charge, deposition mechanisms, etc. (see Annex A). EXAMPLE SCP Class 5 (1 µm) signifies that 1 m2 of surface may carry a maximum of 105 particles with a considered particle size R 1 µm (D = 1). SCP Class 5 (10 µm) signifies that 1 m2 of surface may carry a maximum of 104 particles per square metre with a considered particle size R 10 µm (D = 10). Any other measured particle size (D = x) which leads to a concentration that lies below the relevant SCP class line is within the specification of SCP Class 5 (x µm). Figure 1 — SCP classes For particle sizes out of the classification system and in cases where only a narrow particle range or individual particle sizes are of interest, a descriptor can be used (see Annex B). SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 6 © ISO 2012 – All rights reserved 5.2 Designation The SCP class number shall be formatted as follows: SCP Class N (D µm). The designation of the SCP class for cleanrooms and associated controlled environments shall also include the following: a) the surface type measured; b) the surface area measured; c) the measurement method applied. Details of measurement methods applied, including sampling techniques and measurement devices, should be retrieved from test reports. The considered particle size should be determined by agreement between the customer and supplier. The SCP classification shall be stated in relation to the measured particle size diameter. EXAMPLE 1 SCP Class 2 (0,1 µm); wafer or glass substrate, surface area: 310 cm2; surface particle counter. EXAMPLE 2 SCP Class 5 (0,5 m); inner wall of a bottle, surface area: 200 cm2; liquid dispersion — liquid particle counter. 5.3 General information on surface cleanliness by particle concentration Airborne particle concentration and surface particle concentration are generally related. The relationship is dependent on many factors, such as airflow turbulence, rate of deposition, time of deposition, deposition velocity, concentration within the air, and surface characteristics such as electrostatic charge (see A.2.4). To determine surface cleanliness by particle concentration, various parameters (see Annex C) and surface characteristics (see Annex A) that influence testing should be taken into account. 6 Demonstration of compliance 6.1 Principle Compliance with SCP class requirements, as specified by the customer, is verified by performing tests and by providing documentation of the results and conditions of the testing. Details for demonstrating compliance (see 6.3) shall be agreed upon between the customer and supplier in advance of testing. 6.2 Testing Tests performed to demonstrate compliance shall be conducted in a controlled environment using suitable test methods and calibrated instruments, whenever possible. Direct and indirect test methods can be used for demonstrating compliance and are given in Annex D. The list of typical methods described is not exhaustive. Alternative methods of comparable accuracy may be specified by agreement. NOTE Measurement by different methods, even when correctly applied, can produce different results of equal validity. Repeated measurements are recommended. SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 7 The test method and environment shall be agreed upon between the customer and supplier. Precautions should be taken to reduce electrostatic charge around the test zone, since electrostatic charge enhances particle deposition onto surfaces. If the surface is neither conductive, nor grounded or charge-neutralized, electrostatic charges might occur (see Annex A). Therefore, test results may vary. 6.3 Test report The results from testing each surface shall be recorded and submitted as a comprehensive report, along with a statement of compliance or non-compliance with the specified SCP class(es). The test report shall include as a minimum the following: a) basic data:  date and time of testing;  name/address of the testing organization;  name of testing personnel; b) references consulted:  standards;  guidelines;  regulations;  number and year of publication of this part of ISO 14644, i.e. ISO 14644-9:2012; c) environmental data:  environmental conditions for sampling (i.e. temperature, humidity, cleanliness);  environmental conditions for measurement (i.e. temperature, humidity, cleanliness) (not essential for use with direct methods);  location (room, etc.) used for the measurements; d) specimen:  clear identification of the test object;  description of the test object;  graph and/or sketch of test specimen; e) test setup:  photo and/or sketch of the test setup;  description of operating parameters;  description of measurement points;  description of hardware used in the test setup; SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 8 © ISO 2012 – All rights reserved f) measurement devices:  identification of the instrument(s) and measuring devices used and current calibration certificate(s);  measurement range of measuring devices used;  reference of calibration certificates; g) performing the test:  relevant details of the test procedure used, with any available data describing deviations from the test procedure (if agreed);  surface condition before sampling (e.g. after cleaning, after packaging, under atmospheric or vacuum conditions);  specified test and measurement procedure/method;  occupancy state(s) during sampling and measurement;  specified test method(s);  all agreed documentation (e.g. raw data, background particle concentrations, pictures, graphs, cleaning and packaging);  duration, location and position of sampling (not essential for use with direct methods);  duration, location and position of measurement (not essential for use with direct methods);  noticeable observations made during sampling/measurement, where applicable;  number of measurements performed;  clear identification of the position and the area of the surface measured and specific designations for coordinates of the surface, if applicable; h) results and analysis:  visual inspection of the test surface before and after measurement, where applicable;  measurement values and/or their analysis;  statement of data quality;  particle size ranges considered;  test results, including particle concentration data for given particle sizes, for all tests performed;  surface cleanliness by particle concentration class with designation expressed as SCP Class N;  acceptance criteria for the clean surface, if agreed between the customer and supplier.
ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 9 Annex A (informative)
Surface characteristics A.1 Surface description A surface is commonly characterized by its texture (such as roughness, porosity), its mechanical properties (such as hardness) and its physicochemical properties (such as electrostatic surface charge and surface tension). Each of these properties should be considered before selecting a test method for the surface cleanliness classification, or as an aid for the interpretation of the test results. A.2 Surface characteristics A.2.1 Roughness A.2.1.1 Description As the roughness of a surface affects many of its physical properties, surface roughness is not easily described by one single parameter, nor is it an intrinsic property of the surface. Roughness exists in two principal planes: at right angles to the surface, where it may be characterized by height, and in the plane of the surface, identified as “texture” and characterized by waviness. The roughness of a surface can be determined by mechanical or optical methods. A.2.1.2 Testing A frequently used mechanical method for the determination of roughness is the stylus instrument (for example, see ISO 4287 or ISO 4288). Frequently used optical methods for the determination of roughness and porous texture are microscopes (optical, confocal, interferometry, with/without tunnel effect, taper sectioning). A.2.2 Porosity A.2.2.1 Definition and description Porosity is a measure of the void spaces in a material, and is expressed as a decimal between 0 and 1, or as a percentage between 0 % and 100 %.  Effective porosity (also called open porosity) refers to the fraction of the total volume in which fluid flow is effectively taking place (this excludes dead-end pores or non-connected cavities).  Macroporosity refers to pores equal to or greater than 50 nm in diameter. Fluid flow through macropores is described by bulk diffusion.  Mesoporosity refers to pores equal to or greater than 2 nm but less than 50 nm in diameter.  Microporosity refers to pores smaller than 2 nm in diameter. Movement in micropores is by activated diffusion. SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 10 © ISO 2012 – All rights reserved A.2.2.2 Testing There are several ways to estimate the porosity of a given material or mixture of materials, which is called material matrix. The volume/density method is fast and highly accurate (normally within 2 % of the actual porosity). The volume and the weight of the material are measured. The weight of the material divided by the density of the material gives the volume that the material takes up, minus the pore volume. Therefore, the pore volume is simply equal to the total volume minus the material volume, or more directly (pore volume) = (total volume)  (material volume). The water saturation method is slightly more difficult, but is more accurate and more direct. Take a known volume of the material and a known volume of water. Slowly dump the material into the water and allow it to saturate while pouring. Allow it to sit for a few hours to ensure that the material is fully saturated. Then remove the unsaturated water from the top of the beaker and measure its volume. The total volume of the water originally in the beaker minus the volume of water not saturated is the volume of the pore space, or again more directly (pore volume) = (total volume of water)  (unsaturated water). Mercury intrusion porosimetry requires the sample to be placed in a special filling device that allows the sample to be evacuated, followed by the introduction of liquid mercury. The size of the mercury envelope is then measured as a function of increased applied pressure. The greater the applied pressure, the smaller the pore entered by mercury. Typically, this method is used over the range of pores from 300 µm to 0,0 035 µm. Because of increased safety concerns over the use of mercury, several non-mercury intrusion techniques have been developed and should be considered as alternatives. Nitrogen gas adsorption is used to determine fine porosity in materials. In very small pores, nitrogen gas condenses on pore walls that are less than 0,090 µm in diameter. This condensation is measured either by volume or weight. A.2.3 Hardness There are many National and International Standards on hardness tests for each material type. Hardness is frequently measured by the penetrating force of a diamond ball or tip, by the indentation of a hard body or by the rebound properties of an impactor. The Rockwell, Brinell, Shore and Vickers method for metals is covered by ASTM E18-07. Geometry and pressure are chosen at the beginning of the test, as a function of the thickness of the sample, the composition of the metal and the supposed hardness. A.2.4 Static electricity A.2.4.1 Definition and description Static electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material. This imbalance of electrons produces an electrostatic field that can influence the determination of the surface cleanliness of objects. Electrostatic discharge (ESD) is defined as the transfer of charge between bodies at different electrical potentials. Any relative motion and physical separation of materials or flow of solids, liquids, or particle-laden gases can generate electrostatic charges. Common sources of ESD include personnel, items made from common polymeric materials, and processing equipment. ESD can damage parts by direct contact with a charged source or by electric fields emanating from charged objects. Charged surfaces can attract and hold particle contaminants. If the selected measurement method to determine the surface cleanliness is based on an indirect detection of particles on surfaces (see D.2.3.3.5), these measurement results might be inaccurate, as the particle removal is diminished. Therefore, especially when using indirect measurement methods, action should be taken to reduce ESD effects. SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 11 A.2.4.2 Testing Determination of the ESD properties of the specimen surfaces may be helpful in estimating the influence of the removal efficiency of particles from surfaces (e.g. IEC 61340-5-1, ISO 10015, IEST RP-CC022.2, SEMI E43-0301, SEMI E78-0706). A.2.5 Superficial tension A.2.5.1 Definition Superficial tension is the energy necessary to increase the surface by one area unit. It is usually defined as  and expressed in joules per square metre (J/m2) or in newtons per metre (N/m). A.2.5.2 Testing The best-known method is the measurement of the contact angle by the “set drop” (see Reference [22] in the Bibliography). When a drop of liquid is brought into contact with a flat solid surface, its shape depends on the molecular force within the liquid for cohesive force, or between the liquid and solid for adhesive force. The contact angle between the liquid and solid is used as the surface tension index (see Figure A.1). It is generally found that liquids with low surface tension easily wet most solid surfaces, giving a zero contact angle. The molecular adhesion between solid and liquid is greater than the cohesion between the molecules of the liquid. The contact angle measurement is performed with an optical method (10 to 50) magnifying the drop profile set on the flat solid surface.
Key 1 gas 2 liquid 3 solid Figure A.1 — Shape of a drop of liquid in contact with a solid surface when the contact angle is   90°
ISO 14644-9:2012(E) 12 © ISO 2012 – All rights reserved Annex B (informative)
Descriptor for specific particle size ranges B.1 Application For particle sizes outside the range of the classification system, a differential descriptor can be used. This descriptor can also be used for specific particle size ranges that are of special interest. In these cases, the descriptor can be used in addition to the SCP classification. B.2 Surface descriptor for specific particle size ranges The Nss (particle number concentration of a specific particle size range) descriptor for specific particle size ranges may be specified independently or as a supplement to the SCP classes. The descriptor can be applied to any particle size range of special interest. The surface particle concentration Cs within the particle size range DL and DU is a differential value. The Nss for a single particle size range is expressed in the format: sssLU;;;NCDDab (B.1) where Cs
is the maximum permitted total surface concentration, in particles per square metre of surface, of the specified particle size range; DL is the lower limit of the specified particle size range, in micrometres; DU is the upper limit of the specified particle size range, in micrometres; a is the measurement method used to determine particle size in the specified range; b is the considered surface. EXAMPLE 1 For the particle concentration on a metallic surface in the particle size range between 1 m and 5 m, the required value is 10 000 particles/m2 (1,0 particles/cm2). The particle concentration is measured by an optical microscope. The designation would be: ss10000;1;5opticalmicroscope;metallicsurfaceN
ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 13 If two or more size ranges are used, apply Formula (B.2). Nss is then expressed in the format: s1L1U11s2L2U22sssLU;;;;;;.;;;.iiiiCDDabCDDabNabCDD (B.2) where Csi is the maximum permitted total surface concentration, in particles per square metre of surface, of the i-th particle size range; DLi is the lower limit of the i-th particle size range, in micrometres; DUi is the upper limit of the i-th particle size range, in micrometres; ai is the measurement method used to determine particle size in the i-th range; b is the considered surface. EXAMPLE 2 For the particle concentration on a glass plate, based on the simultaneous use of a scattered-light scanner in the particle size range between 0,1 m and 0,5 m, and an optical microscope in the particle size range between 5 m and 20 m, the measured values are 9 000 particles/m2 (0,9 particles/cm2) and 500 particles/m2 (0,05 particles/cm2), respectively. The values are within the maximum allowable limits of 10 000 particles/m2 and 500 particles/m2, respectively. The designation would be: 10000;0,1;0,5scattered light scanner;
glass platess
optical microscope;
glass plate500;5;20N When measurement methods and/or specific surfaces are not predefined or are not essential, designations a and b might be omitted. In this case, the descriptor is expressed as follows: sssLU;;NCDD (B.3) where Cs is the maximum permitted total surface concentration, in particles per square metre of surface, of the specified particle size range; DL is the lower limit of the specified particle size range, in micrometres; DU is the upper limit of the specified particle size range, in micrometres. Where only one particle size is of interest, the lower and upper limit in Formula (B.3) might be used to frame the particle size of interest through an agreement between the customer and supplier. EXAMPLE 3 For the particle size 5 m, the required value is 200 particles/m2 (0,02 particles/cm2). DL could be set to 4,5 m and DU could be set to 5,5 m. The designation would be: ss200;4,5;5,5N SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 14 © ISO 2012 – All rights reserved When measurement methods and/or specific surfaces are not predefined or are not essential, designations a and b might be omitted. The descriptor for two or more particle size ranges is expressed as follows: s1L1U1s2L2U2sssLU;;;;.;;.iiiCDDCDDNCDD (B.4) EXAMPLE 4 For the particle concentration in the particle size ranges between 0,1 m and 0,5 m and between 5 m and 20 m, the measured values are 9 000 particles/m2 (0,9 particles/cm2) and 500 particles/m2 (0,05 particles/cm2), respectively. They are within the maximum allowable limits of 10 000 particles/m2 and 500 particles/m2, respectively. The designation would be: ss10000;0,1;0,5500;5;20N (B.5)
ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 15 Annex C (informative)
Parameters influencing the SCP classification C.1 Background Parameters that may influence the testing and measuring of surfaces are presented in C.2. The information is not exhaustive and there is no ranking. More detailed information on measurement methods and surface characteristics is given in Annex D. C.2 Parameters C.2.1 Physical/chemical properties  Surface energy states. The attraction and removal of particles might be influenced, for example, by cohesive/adhesive characteristics and/or hydrophilic/hydrophobic properties of the surface.  Porosity of the surface. In most cases, the higher the degree of porosity, the more complex the distinction between surface imperfection and particle detection.  Cleanability of the surface. When surfaces are difficult to clean, the discrimination between surface imperfection and particle detection is complex.  Optical characteristics of the surface. When direct test methods are applied, different optical characteristics of the surface to be tested will lead to different measurement results. This difference is not noted for indirect methods.  Electrostatic properties of the surface. The electrostatic properties of the surface will influence the attraction and removal of ESD-charged contamination.  Magnetic characteristics of the surface. The magnetic characteristics of the surface will influence the attraction and removal of materials with magnetic properties. C.2.2 Shape of the surface and particles  Morphology of the particle (round, flat, oval, peaked, etc.) and topography of the surface can influence the measurement result.  Surface condition (being cleaned, extruded, polished, etc.). The particle attachment force varies depending on the surface condition. This variation also affects the removal efficiency of particles and the ability to distinguish between particles, roughness and porosity.  Roughness/porosity/waviness of the surface. The roughness, porosity or waviness will have an effect on the efficiency of removing particles for indirect methods.  Shape/geometry of particle. The shape of particles can also influence the measurement results. For example, long particles and perfectly round particles can lead to the same optical particle counter values after detaching the particles from the surface, but to completely different gravimetric values. In general, fibres are considered as particles having an aspect (length-to-width) ratio of 10 or more. SIST EN ISO 14644-9:2012

ISO 14644-9:2012(E) 16 © ISO 2012 – All rights reserved C.2.3 Ability to measure/analyse and appropriate statistics for particle analysis The number of measurements should lead to statistically significant results. Therefore, an appropriate statistical method with regard to the frequency distribution of individual measurements should be used to estimate the confidence limit.  Ability to measure/analyse. Feasibility to perform the measurements, depending on the accessibility of a measurement device to the specimen. EXAMPLE Performing measurements within holes or microtubes.  Ability to detect particles (direct or indirect methods). The ability to distinguish between surface sedimented particles and surface imperfections (direct method) or the detachability of surface sedimented particles (indirect method) will influence the SCP classification.  Geometric size/surface area to be measured. Depending on the geometric size of the surface area to be measured, different methods should be selected. In the majority of cases, the statistics for the number of samples to be taken and how to analyse the measurement values should be developed individually.  Inline capability. Several measurements should be taken for statistical significance. The influence of measurement repeatability is diminished with inline options.  Frequency distribution of individual measurements.  Particle size(s) to be measured.  Distribution of particles on surface area. C.2.4 Particle origin Particles on the surface can originate, for example, from material friction, deterioration, deposition of airborne particles or chemical reaction of gaseous matters with the surface, forming solid or liquid products. EXAMPLE 3234422NHHOSONHSO.
ISO 14644-9:2012(E) © ISO 2012 – All rights reserved 17 Annex D (informative)
Measurement methods for determining surface cleanliness by particle concentration D.1 Surface cleanliness by particle concentration In order to obtain quantitative information on surface cleanliness, appropriate measurement methods should be selected. In some cases where quantitative information cannot be ascertained on a surface, it is possible at least to obtain a qualitative result. Qualitative results cannot be used for the surface cleanliness by particle concentration classification defined in Clause 5. D.2 Criteria for the measurement of surface cleanliness by particle concentration D.2.1 General The cleanliness of surfaces can be classified as soon as the particle contamination is detectable. As a quantitative criterion for the evaluation and classification of the surface cleanliness, the number of all adherent particles of undesired material should be determined. It should be possible to determine the dimension and number in relation to the contaminated surface area (surface particle contamination). NOTE The cleanliness classification of textiles and/or porous surfaces also takes into account particles which might emanate from the specimen. D.2.2 Requirements of the measurement method The measurement method is essentially selected according to criteria determined by the surface
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