Environmental testing - Part 3-13: Supporting documentation and guidance on test T: Soldering

This part of IEC 60068 provides background information and guidance for writers and users of
specifications for electric and electronic components, containing references to the test
standards IEC 60068-2-20, IEC 60068-2-58, IEC 60068-2-69, IEC 60068-2-83, and to
IEC 61760-1, which defines requirements to the specification of surface mounting
components.

Umgebungseinflüsse - Teil 3-13: Ergänzende Unterlagen und Anleitung zur Prüfung T - Löten

Essais d'environnement - Partie 3-13: Documentation d'accompagnement et guide sur les essais T: Brasage

L'IEC 60068-3-13:2016 donne des informations de base et des lignes directrices aux rédacteurs et utilisateurs de spécifications relatives aux composants électriques et électroniques, avec des références aux normes d'essai IEC 60068-2-20, IEC 60068-2-58, IEC 60068-2-69 et IEC 60068-2-83, ainsi qu'à l'IEC 61760-1 qui définit les exigences pour la spécification des composants pour montage en surface. L'IEC 60068-3-13 annule et remplace la deuxième édition de l'IEC 60068-2-44. Cette norme constitue une révision technique. Ce document inclut les modifications techniques majeures suivantes par rapport à l'IEC 60068-2-44: - ajout d'informations sur les brasages sans plomb; - mise à jour technique et restructuration.

Okoljsko preskušanje - 3-13. del: Podporna dokumentacija in navodilo za preskus T: Spajkanje

Ta del standarda IEC 60068 podaja dodatne informacije in navodila za avtorje in uporabnike specifikacij za električne in elektronske komponente, ki vsebujejo reference za preskusne standarde IEC 60068-2-20, IEC 60068-2-58, IEC 60068-2-69, IEC 60068-2-83 in IEC 61760-1, ki določajo zahteve za specifikacije komponent za površinsko montažo.

General Information

Status
Published
Publication Date
14-Nov-2016
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
10-Oct-2016
Due Date
15-Dec-2016
Completion Date
15-Nov-2016

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Okoljsko preskušanje - 3-13. del: Podporna dokumentacija in navodilo za preskus T: SpajkanjeEssais d'environnement - Partie 3-13: Documentation d'accompagnement et guide sur les essais T: BrasageEnvironmental testing - Part 3-13: Supporting documentation and guidance on test T: Soldering25.160.01Varjenje, trdo in mehko spajkanje na splošnoWelding, brazing and soldering in general19.040Preskušanje v zvezi z okoljemEnvironmental testing01.110L]GHONHTechnical product documentationICS:Ta slovenski standard je istoveten z:EN 60068-3-13:2016SIST EN 60068-3-13:2016en01-december-2016SIST EN 60068-3-13:2016SLOVENSKI

STANDARDSIST EN 60068-2-44:20011DGRPHãþD
SIST EN 60068-3-13:2016
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 60068-3-13
September 2016 ICS 19.040
Supersedes
EN 60068-2-44:1995
English Version

Environmental testing - Part 3-13: Supporting documentation and guidance on Test T - Soldering (IEC 60068-3-13:2016)

Essais d'environnement - Partie 3-13: Documentation d'accompagnement et guide sur les essais T - Brasage (IEC 60068-3-13:2016)

Umweltprüfungen - Teil 3-13: Ergänzende Unterlagen und Anleitung zur Prüfung T: Löten (IEC 60068-3-13:2016) This European Standard was approved by CENELEC on 2016-06-17. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization

Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17,

B-1000 Brussels © 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 60068-3-13:2016 E SIST EN 60068-3-13:2016

EN 60068-3-13:2016 2 European foreword The text of document 91/1345/FDIS, future edition 1 of IEC 60068-3-13, prepared by IEC/TC 91 "Electronics assembly technology" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 60068-3-13:2016.

The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2017-03-17 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2019-06-17

This document supersedes EN 60068-2-44:1995.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.

Endorsement notice The text of the International Standard IEC 60068-3-13:2016 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60068-2 Series NOTE Harmonized as EN 60068-2 Series. IEC 60749-20 NOTE Harmonized as EN 60749-20. IEC 61190-1-1 NOTE Harmonized as EN 61190-1-1. IEC 61191 Series NOTE Harmonized as EN 61191 Series. IEC 61192 Series NOTE Harmonized as EN 61192 Series. IEC 61760-4 NOTE Harmonized as EN 61760-4. SIST EN 60068-3-13:2016

EN 60068-3-13:2016 3 Annex ZA (normative)

Normative references to international publications with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu

Publication Year Title EN/HD Year
IEC 60068-2-20 2008
Environmental testing -

Part 2-20: Tests - Test T: Test methods for solderability and resistance to soldering heat of devices with leads EN 60068-2-20 2008

IEC 60068-2-58 -
Environmental testing -

Part 2-58: Tests - Test Td: Test methods for solderability, resistance to dissolution of metallization and to soldering heat of surface mounting devices (SMD) EN 60068-2-58 -

IEC 60068-2-69 -
Environmental testing -

Part 2: Tests - Test Te: Solderability testing of electronic components for surface mounting devices (SMD) by the wetting balance method EN 60068-2-69 -

IEC 60068-2-83 -
Environmental testing -

Part 2-83: Tests - Test Tf: Solderability testing of electronic components for surface mounting devices (SMD) by the wetting balance method using solder paste EN 60068-2-83 -

IEC 61760-1 -
Surface mounting technology -

Part 1: Standard method for the specification of surface mounting components (SMDs) EN 61760-1 -

IEC 62137-3 -
Electronics assembly technology -
Part 3:

Selection guidance of environmental and endurance test methods for solder joints EN 62137-3 -

SIST EN 60068-3-13:2016
SIST EN 60068-3-13:2016

IEC 60068-3-13 Edition 1.0 2016-05 INTERNATIONAL STANDARD NORME INTERNATIONALE Environmental testing –

Part 3-13: Supporting documentation and guidance on Test T – Soldering
Essais d'environnement –
Partie 3-13: Documentation d'accompagnement et guide sur les essais T – Brasage

INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE

ICS 19.040
ISBN 978-2-8322-3359-7
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. SIST EN 60068-3-13:2016

– 2 – IEC 60068-3-13:2016  IEC 2016 CONTENTS FOREWORD ......................................................................................................................... 4 1 Scope ............................................................................................................................ 6 2 Normative references..................................................................................................... 6 3 Terms, definitions and abbreviations .............................................................................. 6 3.1 Terms and definitions ............................................................................................ 6 3.2 Abbreviations ........................................................................................................ 7 4 Overview ....................................................................................................................... 7 4.1 Factors influencing the formation and reliability of solder joints (ability to be soldered) .............................................................................................................. 7 4.2 Physics of surface wetting ..................................................................................... 8 4.3 Quality and reliability of solder joints ................................................................... 10 5 Component soldering – Processes ............................................................................... 10 5.1 General considerations ........................................................................................ 10 5.1.1 Components' ability to be soldered ............................................................... 10 5.1.2 Soldering processes ..................................................................................... 12 5.1.3 Soldering defects ......................................................................................... 12 5.1.4 Geometrical factors which may influence the soldering result ........................ 12 5.1.5 Process factors ............................................................................................ 12 5.1.6 Material factors ............................................................................................ 12 5.2 Solder ................................................................................................................. 13 5.3 Grouping of soldering conditions ......................................................................... 13 5.4 Ability to be soldered ........................................................................................... 13 5.5 Moisture sensitivity of components ...................................................................... 13 5.6 Relation between storage time/storage conditions and solderability ...................... 14 5.6.1 Natural and accelerated ageing .................................................................... 14 5.6.2 Oxidation ..................................................................................................... 14 5.6.3 Growth of intermetallic layers ....................................................................... 14 5.6.4 Effect of ageing to wetting characteristics ..................................................... 14 5.6.5 Test conditions for accelerated ageing .......................................................... 15 5.7 Place of soldering tests in testing ........................................................................ 16 6 Soldering tests ............................................................................................................ 17 6.1 General ............................................................................................................... 17 6.2 Solder ................................................................................................................. 18 6.3 Fluxes ................................................................................................................. 18 6.4 Test equipment ................................................................................................... 18 6.5 Evaluation methods ............................................................................................. 18 6.5.1 Criteria for visual inspection ......................................................................... 18 6.5.2 Criteria for quantitative evaluation of the wetting characteristic ..................... 19 6.5.3 Special cases .............................................................................................. 19 6.6 Acceptance criteria ............................................................................................. 19 7 Soldering tests – Methods ............................................................................................ 19 7.1 General principles ............................................................................................... 19 7.2 Survey of test methods ........................................................................................ 19 7.3 Bath test ............................................................................................................. 22 7.4 Reflow test .......................................................................................................... 23 7.4.1 With/without solder land ............................................................................... 23 SIST EN 60068-3-13:2016

IEC 60068-3-13:2016  IEC 2016 – 3 – 7.4.2 Selection of solder paste (flux system and activity grade) .............................. 23 7.5 Soldering iron test ............................................................................................... 23 7.6 Resistance to dissolution of metallization and soldering heat ................................ 23 7.6.1 General ....................................................................................................... 23 7.6.2 Limitations ................................................................................................... 23 7.6.3 Choice of severity ........................................................................................ 24 7.7 Wetting balance test ............................................................................................ 24 7.7.1 General ....................................................................................................... 24 7.7.2 Test methods available ................................................................................ 25 7.7.3 Limitations ................................................................................................... 25 8 Requirements and statistical character of results .......................................................... 25 Bibliography ....................................................................................................................... 27

Figure 1 – Sessile drop of solder on oxidised copper ............................................................. 8 Figure 2 – Sessile drop of solder plus flux on clean copper .................................................... 9 Figure 3 – Sessile drop equilibrium forces ............................................................................. 9 Figure 4 – Typical soldering processes ................................................................................ 12 Figure 5 – Soldering tests for devices with leads ................................................................. 21 Figure 6 – Soldering tests for SMDs .................................................................................... 22

Table 1 – Solder process groups ......................................................................................... 13

SIST EN 60068-3-13:2016

– 4 – IEC 60068-3-13:2016  IEC 2016 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________

ENVIRONMENTAL TESTING –
Part 3-13: Supporting documentation and guidance on Test T – Soldering

FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60068-3-13 has been prepared by IEC technical committee 91: Electronics assembly technology. This first edition cancels and replaces IEC 60068-2-44:1995 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: – information for lead-free solders are added; – technical update and restructuring.

SIST EN 60068-3-13:2016

IEC 60068-3-13:2016  IEC 2016 – 5 – The text of this standard is based on the following documents: FDIS Report on voting 91/1345/FDIS 91/1356/RVD

Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60068 series, published under the general title Environmental testing, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be • reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.

SIST EN 60068-3-13:2016
– 6 – IEC 60068-3-13:2016  IEC 2016 ENVIRONMENTAL TESTING –
Part 3-13: Supporting documentation and guidance on Test T – Soldering

1 Scope This part of IEC 60068 provides background information and guidance for writers and users of specifications for electric and electronic components, containing references to the test standards IEC 60068-2-20, IEC 60068-2-58, IEC 60068-2-69, IEC 60068-2-83, and to IEC 61760-1, which defines requirements to the specification of surface mounting components. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60068-2-20:2008, Environmental testing – Part 2: Tests – Test T: Test methods for solderability and resistance to soldering heat of devices with leads IEC 60068-2-58, Environmental testing – Part 2-58: Tests – Test Td: Test methods for solderability, resistance to dissolution of metallization and to soldering heat of surface mounting devices (SMD) IEC 60068-2-69, Environmental testing – Part 2-69: Tests – Test Te: Solderability testing of electronic components for surface mounting devices (SMD) by the wetting balance method1 IEC 60068-2-83, Environmental testing – Part 2-83: Tests – Test Tf: Solderability testing of electronic components for surface mounting devices (SMD) by the wetting balance method using solder paste IEC 61760-1, Surface mounting technology – Part 1: Standard method for the specification of surface mounting components (SMDs) IEC 62137-3, Electronics assembly technology – Part 3: Selection guidance of environmental and endurance test methods for solder joints 3 Terms, definitions and abbreviations 3.1 Terms and definitions For the purposes of this document the following terms and definitions apply. 3.1.1

solderability ability of the lead, termination or electrode of a component to be wetted by solder at the temperature of the termination or electrode, which is assumed to be the lowest temperature in the soldering process within the applicable temperature range of the solder alloy ________________ 1

A new edition (third edition) is currently under consideration. SIST EN 60068-3-13:2016

IEC 60068-3-13:2016  IEC 2016 – 7 – Note 1 to entry: The term “solderability” is often used in combination with the term “test”, indicating a specific method to evaluate the wettability or ability to be soldered of a surface under worst case conditions (soldering temperature and contact time with solder). It is not to be confused with the concepts “ability to be soldered” (see 4.1, 5.1.1) or “soldering ability” (see 3.1.4). 3.1.2

resistance to soldering heat ability of the component to withstand the highest temperature stress in terms of temperature gradient, peak temperature and duration of the soldering process, where the temperature of the component body is within the applicable temperature range of solder alloy 3.1.3

wettability intrinsic property of the termination material to form an alloy with the solder Note 1 to entry: Wettability depends on the base metal used to produce the termination or, in the case of a plated termination, the condition and material used to plate the base metal. 3.1.4

soldering ability ability of a specific combination of components to facilitate the formation of a proper solder joint Note 1 to entry: See 3.1.3, wettability. 3.2 Abbreviations SMD Surface mounted device SMT Surface mounting technology THD Through-hole mounting device THT Through-hole mounting technology THR Through-hole reflow soldering 4 Overview 4.1 Factors influencing the formation and reliability of solder joints (ability to be soldered) The conditions of ease of production and the reliability of a soldered joint can be classified in three groups, as follows. a) The joint design, determined by the choice of the two metallic elements to be joined (their shape, size, composition, etc.) and of the assembly method (relative position, initial fastening, etc.). b) The wettability of the surfaces to be joined. c) The conditions adopted for the soldering operation (temperature, time, flux, solder alloy, equipment, etc.). The choice of conditions of groups a) and c) concerns the manufacturer of equipment or subassemblies, who shall know the importance of each of the conditions and the limits of their variation. Condition b) depends to a large extent on the component manufacturer, except in cases of unusual handling or storage conditions by the equipment manufacturer. The wettability of surfaces needs to be defined with whatever degree of precision is necessary to allow the equipment manufacturer to choose conditions of classes a) and c) appropriate to that wettability. On the other hand, components of satisfactory surface quality will not necessarily prevent rejectable joints arising from faults in joint design or joining conditions. SIST EN 60068-3-13:2016

– 8 – IEC 60068-3-13:2016  IEC 2016 This often complex overlapping of responsibilities between component manufacturers and equipment manufacturers creates a need to be able to define with considerable precision the wettability of component terminations or, more generally, the solderability of components. 4.2 Physics of surface wetting In order to obtain wetting between a substrate and molten solder, the tin in the solder shall react with the substrate to form an alloy. In order to form an alloy the tin and the substrate has to come into molecular contact. In order to do this the surface of both the molten solder and the substrate shall be free from contamination. In order to better understand how molten solder spreads over a substrate, and what determines solderability, the surface tension property of the solder needs to be examined. A free droplet of molten solder held in free space will form into a globule shape, just as a free drop of water will form into a spherical shape. The droplet is held in this shape by the surface tension force of the molten solder. Inside the droplet the atoms are uniformly surrounded by other atoms, and the net force on them is zero, ignoring thermal motion. At the surface there is an imbalance in the inter-atomic attraction forces, as the surface atoms experience a net force into the body of the droplet. The complete system tries to adopt a shape that has the minimum free energy, which means the minimum surface-to-volume ratio. This situation is achieved when the molten solder forms into a sphere. The strength of the surface tension force is determined by the bond energies between the atoms within the molten solder. If the molten sphere of solder is placed onto a heated, oxidised copper plate, the shape of the sphere is depressed by gravity, to form a sessile drop, as shown in Figure 1 below.

Figure 1 – Sessile drop of solder on oxidised copper If a suitable flux is added to the sessile drop on the oxidised copper, the oxide layer will be removed from the copper and the solder, and the tin in the solder will react with the copper to form an intermetallic layer, allowing the solder to spread, as shown in Figure 2 below. IEC Solder Oxide layer SIST EN 60068-3-13:2016

IEC 60068-3-13:2016  IEC 2016 – 9 –

Figure 2 – Sessile drop of solder plus flux on clean copper The final shape of the spreading solder will depend on the surface tension forces acting at the interfaces. Solid and solid-liquid interfaces also exert a surface tension force, and all try to reduce their surface areas to a minimum to attain a minimum free energy. As a result equilibrium is reached whereby the net force at the advancing solder front is zero. Figure 3 below shows the forces acting at the advancing solder front. The surface tension of the solid copper in air is balanced by the surface tension between the liquid solder and the air, and the liquid solder and the solid copper.

Figure 3 – Sessile drop equilibrium forces The resulting forces at the advancing solder front can be written as follows: SA = LS + LA cos

where SA is surface tension between solid copper and air; LS is surface tension between liquid solder and solid copper; LA is surface tension between liquid solder and air. This equation is known as Young’s equation. The contact angle

can be used as a measure of the degree of spreading obtained. The smaller the contact angle, the greater the spreading, and the better the wetting obtained. If the cohesive forces within the solder are greater than the adhesive forces between the solder and the copper, then the solder will remain as a non-spreading sessile drop, and the contact angle will be greater than 90°. If the adhesive forces exceed the cohesive forces, then it is energetically favourable for the solder to react with the copper and spread outward, reducing the contact angle below 90°. IEC Solder Diffusion layer IEC γLA γLS γSA θ SIST EN 60068-3-13:2016

– 10 – IEC 60068-3-13:2016  IEC 2016 The surface tension between solid and air, SA, will be high when the solid is free from oxides, sulphides, chlorides, hydrocarbons and other surface contaminants, which will all reduce the surface tension. For the surface tension between liquid and solid, LS, to be low, a metallurgical bond has to be formed between the tin and the substrate. The surface tension between liquid solder and air, or flux film, will depend on the solder alloy, the soldering temperature and the flux used to solder the parts. The surface tension of the alloy can be markedly affected by the impurities in the solder. Very small levels of impurity can have a large effect on the surface tension. This is because the surface tension of a liquid is determined by the surface composition of the solder and not the composition of the bulk of the solder. Impurities with low surface energies will rapidly segregate to the surface of the liquid, reducing the surface tension, LA. Impurities in the solder alloy, and changes to the alloy composition may also affect the surface tension between the liquid and the solid, altering the intermetallic formation, and can also affect the surface tension between the solid and the air, affecting the diffusion process across the solid, ahead of the liquid front. Alloy additions or impurities may also affect the spreading and wetting properties of an alloy, by altering the viscosity of the liquid solder. 4.3 Quality and reliability of solder joints The quality of solder joints is characterised by wetted area, wetting angle, microstructure and specific visual criteria. One factor affecting the reliabil

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