Metallic coatings - Determination of porosity in gold coatings on metal substrates - Nitric acid vapour test (ISO 14647:2000)

This International Standard specifies equipment and a method for using nitric acid vapour to determine porosity in gold coatings, particularly electrodeposits and clad metals used on electrical contacts.
This method is designed to show whether the porosity level is less than or greater than some value that, by experience, is considered by the user to be acceptable for the intended application.
It is suitable for inlays or claddings containing 75 % or more of gold, for electrodeposits containing 95 % or more of gold or for substrates of copper, nickel and their alloys that are commonly used in electrical contacts.
The nitric acid vapour test is too severe to be used for gold coatings less than 0,6 μm thick. It is also not suitable for coatings that are less noble than gold or platinum, such as palladium and its alloys, or gold-flashed palladium and its alloys.
Several other porosity testing methods are described in ISO 10308 and in the literature (see e.g. Bibliography, [1] and [2]).

Metallische Überzüge - Bestimmung der Porosität in Goldbeschichtungen auf Metallsubstraten - Salpetersäure-Dampftest (ISO 14647:2000)

Diese Internationale Norm legt die Prüfeinrichtung und ein Verfahren zur Bestimmung der Porosität mittels Salpetersäuredampf in Goldüberzügen, insbesondere galvanische Abscheidungen und Plattierungen, für elektrische Kontakte fest.
Dieses Verfahren beabsichtigt aufzuzeigen, ob die Porosität geringer oder größer als ein Wert ist, der vom Anwender als erfahrungsgemäß zulässig für den vorgesehenen Verwendungszweck gilt.
Sie ist geeignet für Inlays oder Plattierungen, die mindestens 75 % Gold enthalten, für galvanische Überzüge, die mehr als 95 % Gold enthalten, oder für Grundwerkstoffe aus Kupfer, Nickel und deren Legierungen, die gewöhnlich für elektrische Kontakte verwendet werden.
Die Prüfung mit Salpetersäuredampf ist für Goldüberzüge mit einer geringeren Dicke als 0,6 µm zu streng. Außerdem ist diese Prüfung ungeeignet für metallische Überzüge, die weniger edel als Gold oder Platin sind, z. B. Palladium und dessen Legierungen oder teilvergoldetes Palladium und dessen Legierungen.
In ISO 10308 und in der Literatur (siehe z. B. Literaturhinweise [1] und [2]) sind mehrere andere Porositätsprüfverfahren beschrieben.

Revêtements métalliques - Détermination de la porosité des revêtements d'or sur les substrats de métal - Essai à la vapeur d'acide nitrique (ISO 14647:2000)

Kovinske prevleke - Ugotavljanje poroznosti v zlatih prevlekah na kovinskih podlagah - Preskus s hlapi dušikove kisline (ISO 14647:2000)

Ta mednarodni standard določa opremo in metodo za uporabo hlapov dušikove kisline pri ugotavljanju poroznosti v zlatih prevlekah, zlasti v galvanskih prevlekah in ploščah, prevlečenih s kovino, ki se uporabljajo za električne kontakte. Ta metoda je zasnovana tako, da pokaže, ali je raven poroznosti manjša ali večja od določene vrednosti, ki na podlagi uporabnikovih izkušenj velja kot sprejemljiva za predvideno uporabo. Primerna je za vložke ali obloge z vsebnostjo 75 % ali več zlata, galvanske prevleke z vsebnostjo 95 % ali več zlata ali podlage iz bakra, niklja in njunih zlitin, ki se pogosto uporabljajo za električne kontakte. Preizkus s hlapi dušikove kisline na zlatih prevlekah z debelino, manjšo od 0,6 μm, je prezahteven. Prav tako ni primeren za prevleke, ki so manj plemenite kot zlato ali platina, npr. paladij in njegove zlitine ali z zlatom prevlečen paladij in njegove zlitine. V standardu ISO 10308 in literaturi (glej bibliografijo [1] in [2]) je opisanih več drugih metod preskušanja poroznosti.

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Status
Published
Publication Date
19-Apr-2016
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
20-Apr-2016
Completion Date
20-Apr-2016

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SLOVENSKI STANDARD
SIST EN ISO 14647:2016
01-julij-2016
Kovinske prevleke - Ugotavljanje poroznosti v zlatih prevlekah na kovinskih
podlagah - Preskus s hlapi dušikove kisline (ISO 14647:2000)

Metallic coatings - Determination of porosity in gold coatings on metal substrates - Nitric

acid vapour test (ISO 14647:2000)
Metallische Überzüge - Bestimmung der Porosität in Goldbeschichtungen auf
Metallsubstraten - Salpetersäure-Dampftest (ISO 14647:2000)

Revêtements métalliques - Détermination de la porosité des revêtements d'or sur les

substrats de métal - Essai à la vapeur d'acide nitrique (ISO 14647:2000)
Ta slovenski standard je istoveten z: EN ISO 14647:2016
ICS:
25.220.40 Kovinske prevleke Metallic coatings
SIST EN ISO 14647:2016 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 14647:2016
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SIST EN ISO 14647:2016
EN ISO 14647
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2016
EUROPÄISCHE NORM
ICS 25.220.40
English Version
Metallic coatings - Determination of porosity in gold
coatings on metal substrates - Nitric acid vapour test (ISO
14647:2000)

Revêtements métalliques - Détermination de la Metallische Überzüge - Bestimmung der Porosität in

porosité des revêtements d'or sur les substrats de Goldbeschichtungen auf Metallsubstraten -

métal - Essai à la vapeur d'acide nitrique (ISO Salpetersäure-Dampftest (ISO 14647:2000)

14647:2000)
This European Standard was approved by CEN on 2 April 2016.

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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14647:2016 E

worldwide for CEN national Members.
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SIST EN ISO 14647:2016
EN ISO 14647:2016 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 14647:2016
EN ISO 14647:2016 (E)
European foreword

The text of ISO 14647:2000 has been prepared by Technical Committee ISO/TC 107 “Metallic and other

inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over

as EN ISO 14647:2016 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the

secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by October 2016, and conflicting national standards shall

be withdrawn at the latest by October 2016.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent

rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: 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 the United Kingdom.
Endorsement notice

The text of ISO 14647:2000 has been approved by CEN as EN ISO 14647:2016 without any modification.

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SIST EN ISO 14647:2016
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SIST EN ISO 14647:2016
INTERNATIONAL ISO
STANDARD 14647
First edition
2000-03-15
Metallic coatings — Determination of
porosity in gold coatings on metal
substrates — Nitric acid vapour test
Revêtements métalliques — Détermination de la porosité des revêtements
d'or sur les substrats de métal — Essai à la vapeur d'acide nitrique
Reference number
ISO 14647:2000(E)
ISO 2000
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SIST EN ISO 14647:2016
ISO 14647:2000(E)
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ii © ISO 2000 – All rights reserved
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SIST EN ISO 14647:2016
ISO 14647:2000(E)
Contents Page

Foreword.....................................................................................................................................................................iv

Introduction.................................................................................................................................................................v

1 Scope ..............................................................................................................................................................1

2 Normative references ....................................................................................................................................1

3 Terms and definitions ...................................................................................................................................2

4 Apparatus .......................................................................................................................................................2

5 Reagent...........................................................................................................................................................3

6 Safety ..............................................................................................................................................................3

7 Procedure .......................................................................................................................................................3

8 Precision.........................................................................................................................................................5

9 Test report ......................................................................................................................................................5

Annex A (informative) Time of exposure to nitric acid vapour...............................................................................6

Annex B (informative) Procedure recommended for avoiding the use of chlorinated hydrocarbons ...............7

Bibliography................................................................................................................................................................8

© ISO 2000 – All rights reserved iii
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SIST EN ISO 14647:2016
ISO 14647:2000(E)
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 3.

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 International Standard may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

International Standard ISO 14647 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic

coatings, Subcommittee SC 7, Corrosion tests.
Annexes A and B of this International Standard are for information only.
iv © ISO 2000 – All rights reserved
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SIST EN ISO 14647:2016
ISO 14647:2000(E)
Introduction

Gold coatings are often specified for the contacts of separable electrical connectors and other devices.

Electrodeposits are the form of gold that is most used on contacts, although it is also employed as clad metal and

as weldments on the contact surface. The intrinsic nobility of gold enables it to resist the formation of insulating

oxide films that could interfere with reliable contact operation.

In order that the nobility of gold be assured, porosity, cracks, and other defects in the coating that expose base

metal substrates and underplates should be minimal or absent, except in those cases where it is feasible to use the

contacts in structures that shield the surface from the environment or where corrosion inhibiting surface treatments

for the deposit are employed. The level of porosity in the coating that may be tolerable depends on the severity of

the environment to the underplate or substrate, design factors for the contact device like the force with which it is

mated, circuit parameters, and the reliability of contact operation that it is necessary to maintain. Also, when

present, the location of pores on the surface is important. If the pores are few in number and are outside the zone

of contact of the mating surfaces, their presence can often be tolerated.

Methods for determining pores on a contact surface are most suitable if they enable their precise location and

numbers to be determined. Contact surfaces are often curved or irregular in shape, and test methods should be

suitable for them. In addition, the severity of porosity-determining tests may vary. The test method described in this

International Standard is regarded as severe.

The relationship of porosity levels revealed by particular tests to contact behavior should be made by the user of

these tests through practical experience or by judgement. Thus, absence of porosity in the coating may be a

requirement for some applications, while a few pores on the critical surfaces may be acceptable for another. Such

acceptance (or pass-fail) criteria should be part of the product specification for the particular product or part

requiring the porosity test.

The test method described is highly sensitive and is capable of detecting virtually all porosity or other defects in

gold coatings that could participate in substrate corrosion reactions. It is rapid, simple and inexpensive. In addition,

it can be used on contacts having complex geometry such as pin-socket contacts. However, it is preferred that

deeply recessed sockets are opened to expose their critical surfaces prior to testing.

The test method described is considered destructive in that it reveals the presence of porosity by contaminating the

surface with corrosion products and by undercutting the coating at pore sites or at the boundaries of unplated

areas. Any parts exposed to these tests should not be placed in service.

The test described involves corrosion reactions in which the products delineate defect sites in coatings. Since the

chemistry, and properties of these products may not resemble those found in natural or service environments,

these tests are not recommended for prediction of the electrical performance of contacts unless correlation is first

established with service experience.

The test method described employs nitric acid (HNO ) vapour at low relative humidity. Reaction of the gas mixture

with a corrodible base metal at pore sites produces reaction products that appear as discrete spots on the gold

surface. Individual spots are counted with the aid of a lens or low-power stereomicroscope.

The test method described is intended to be used for quantitative descriptions of porosity (such as number of pores

per unit area or per contact) only on coatings that have a pore density sufficiently low that the corrosion sites are

well separated and can be readily resolved. As a general guideline this can be achieved for pore densities up to

about 100 per square centimetre or per 100 contacts. Above this value the tests are useful for the qualitative

detection and comparison of porosity.
© ISO 2000 – All rights reserved v
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SIST EN ISO 14647:2016
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SIST EN ISO 14647:2016
INTERNATIONAL STANDARD ISO 14647:2000(E)
Metallic coatings — Determination of porosity in gold coatings on
metal substrates — Nitric acid vapour test

WARNING: This International Standard does not purport to address all of the safety problems, if any,

associated with its use. It is the responsibility of the user of this International Standard to establish

appropriate safety and health practices and to determine the applicability of regulatory limitations prior

...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.NRYLQVNLKMetallische Überzüge - Bestimmung der Porosität in Goldbeschichtungen auf Metallsubstraten - Salpetersäure-Dampftest (ISO 14647:2000)Revêtements métalliques - Détermination de la porosité des revêtements d'or sur les substrats de métal - Essai à la vapeur d'acide nitrique (ISO 14647:2000)Metallic coatings - Determination of porosity in gold coatings on metal substrates - Nitric acid vapour test (ISO 14647:2000)25.220.40Kovinske prevlekeMetallic coatingsICS:Ta slovenski standard je istoveten z:FprEN ISO 14647kSIST FprEN ISO 14647:2015en,fr,de01-december-2015kSIST FprEN ISO 14647:2015SLOVENSKI

STANDARD
kSIST FprEN ISO 14647:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN ISO 14647
October
t r s w ICS
t wä t t rä v r English Version

Metallic coatings æ Determination of porosity in gold Revêtements métalliques æ Détermination de la porosité des revêtements d 5or sur les substrats de

Metallische Überzüge æ Bestimmung der Porosität in Goldbeschichtungen auf Metallsubstraten æ This draft European Standard is submitted to CEN members for unique acceptance procedureä It has been drawn up by the

If this draft becomes a European Standardá CEN members are bounwhich stipulate the conditions for giving this European Standard the status of a national standard without any alterationä

This draft European Standard was established by CEN in three ofer language made by translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

Recipients of this draft are invited to submitá with their commentsá notification of any relevant patent rights of which they are aware and to provide supporting documentationä

Warning ã This document is not a European Standardä It is distributed for review and commentsä It is subject to change without notice and shall not be referred to as a European Standardä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s w CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä FprEN ISO

s v x v yã t r s w EkSIST FprEN ISO 14647:2015

FprEN ISO 14647:2015 (E) 2 Contents Page European foreword ....................................................................................................................................................... 3 kSIST FprEN ISO 14647:2015

FprEN ISO 14647:2015 (E) 3 European foreword The text of ISO 14647:2000 has been prepared by Technical Committee ISO/TC 107 “Metallic and other inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over as FprEN ISO 14647:2015 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This document is currently submitted to the Unique Acceptance Procedure. Endorsement notice The text of ISO 14647:2000 has been approved by CEN as FprEN ISO 14647:2015 without any modification. kSIST FprEN ISO 14647:2015

kSIST FprEN ISO 14647:2015

ReferencenumberISO14647:2000(E)©ISO2000INTERNATIONALSTANDARDISO14647Firstedition2000-03-15Metalliccoatings—Determinationofporosityingoldcoatingsonmetalsubstrates—NitricacidvapourtestRevêtementsmétalliques—Déterminationdelaporositédesrevêtementsd'orsurlessubstratsdemétal—Essaiàlavapeurd'acidenitriquekSIST FprEN ISO 14647:2015

ISO14647:2000(E)PDFdisclaimerThisPDFfilemaycontainembeddedtypefaces.InaccordancewithAdobe'slicensingpolicy,thisfilemaybeprintedorviewedbutshallnotbeeditedunlessthetypefaceswhichareembeddedarelicensedtoandinstalledonthecomputerperformingtheediting.Indownloadingthisfile,partiesacceptthereintheresponsibilityofnotinfringingAdobe'slicensingpolicy.TheISOCentralSecretariatacceptsnoliabilityinthisarea.AdobeisatrademarkofAdobeSystemsIncorporated.DetailsofthesoftwareproductsusedtocreatethisPDFfilecanbefoundintheGeneralInforelativetothefile;thePDF-creationparameterswereoptimizedforprinting.EverycarehasbeentakentoensurethatthefileissuitableforusebyISOmemberbodies.Intheunlikelyeventthataproblemrelatingtoitisfound,pleaseinformtheCentralSecretariatattheaddressgivenbelow.©ISO2000Allrightsreserved.Unlessotherwisespecified,nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromeitherISOattheaddressbeloworISO'smemberbodyinthecountryoftherequester.ISOcopyrightofficeCasepostale56CH-1211Geneva20Tel.+41227490111Fax+41227341079E-mailcopyright@iso.chWebwww.iso.chPrintedinSwitzerlandii©ISO2000–AllrightsreservedkSIST FprEN ISO 14647:2015

ISO14647:2000(E)©ISO2000–AllrightsreservediiiContentsPageForeword.....................................................................................................................................................................ivIntroduction.................................................................................................................................................................v1Scope..............................................................................................................................................................12Normativereferences....................................................................................................................................13Termsanddefinitions...................................................................................................................................24Apparatus.......................................................................................................................................................25Reagent...........................................................................................................................................................36Safety..............................................................................................................................................................37Procedure.......................................................................................................................................................38Precision.........................................................................................................................................................59Testreport......................................................................................................................................................5AnnexA(informative)Timeofexposuretonitricacidvapour...............................................................................6AnnexB(informative)Procedurerecommendedforavoidingtheuseofchlorinatedhydrocarbons...............7Bibliography................................................................................................................................................................8kSIST FprEN ISO 14647:2015

ISO14647:2000(E)iv©ISO2000–AllrightsreservedForewordISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISOmemberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnicalcommittees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhastherighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnon-governmental,inliaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnicalCommission(IEC)onallmattersofelectrotechnicalstandardization.InternationalStandardsaredraftedinaccordancewiththerulesgivenintheISO/IECDirectives,Part3.DraftInternationalStandardsadoptedbythetechnicalcommitteesarecirculatedtothememberbodiesforvoting.PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote.AttentionisdrawntothepossibilitythatsomeoftheelementsofthisInternationalStandardmaybethesubjectofpatentrights.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.InternationalStandardISO14647waspreparedbyTechnicalCommitteeISO/TC107,Metallicandotherinorganiccoatings,SubcommitteeSC7,Corrosiontests.AnnexesAandBofthisInternationalStandardareforinformationonly.kSIST FprEN ISO 14647:2015

ISO14647:2000(E)©ISO2000–AllrightsreservedvIntroductionGoldcoatingsareoftenspecifiedforthecontactsofseparableelectricalconnectorsandotherdevices.Electrodepositsaretheformofgoldthatismostusedoncontacts,althoughitisalsoemployedascladmetalandasweldmentsonthecontactsurface.Theintrinsicnobilityofgoldenablesittoresisttheformationofinsulatingoxidefilmsthatcouldinterferewithreliablecontactoperation.Inorderthatthenobilityofgoldbeassured,porosity,cracks,andotherdefectsinthecoatingthatexposebasemetalsubstratesandunderplatesshouldbeminimalorabsent,exceptinthosecaseswhereitisfeasibletousethecontactsinstructuresthatshieldthesurfacefromtheenvironmentorwherecorrosioninhibitingsurfacetreatmentsforthedepositareemployed.Thelevelofporosityinthecoatingthatmaybetolerabledependsontheseverityoftheenvironmenttotheunderplateorsubstrate,designfactorsforthecontactdeviceliketheforcewithwhichitismated,circuitparameters,andthereliabilityofcontactoperationthatitisnecessarytomaintain.Also,whenpresent,thelocationofporesonthesurfaceisimportant.Iftheporesarefewinnumberandareoutsidethezoneofcontactofthematingsurfaces,theirpresencecanoftenbetolerated.Methodsfordeterminingporesonacontactsurfacearemostsuitableiftheyenabletheirpreciselocationandnumberstobedetermined.Contactsurfacesareoftencurvedorirregularinshape,andtestmethodsshouldbesuitableforthem.Inaddition,theseverityofporosity-determiningtestsmayvary.ThetestmethoddescribedinthisInternationalStandardisregardedassevere.Therelationshipofporositylevelsrevealedbyparticularteststocontactbehaviorshouldbemadebytheuseroftheseteststhroughpracticalexperienceorbyjudgement.Thus,absenceofporosityinthecoatingmaybearequirementforsomeapplications,whileafewporesonthecriticalsurfacesmaybeacceptableforanother.Suchacceptance(orpass-fail)criteriashouldbepartoftheproductspecificationfortheparticularproductorpartrequiringtheporositytest.Thetestmethoddescribedishighlysensitiveandiscapableofdetectingvirtuallyallporosityorotherdefectsingoldcoatingsthatcouldparticipateinsubstratecorrosionreactions.Itisrapid,simpleandinexpensive.Inaddition,itcanbeusedoncontactshavingcomplexgeometrysuchaspin-socketcontacts.However,itispreferredthatdeeplyrecessedsocketsareopenedtoexposetheircriticalsurfacespriortotesting.Thetestmethoddescribedisconsidereddestructiveinthatitrevealsthepresenceofporositybycontaminatingthesurfacewithcorrosionproductsandbyundercuttingthecoatingatporesitesorattheboundariesofunplatedareas.Anypartsexposedtothesetestsshouldnotbeplacedinservice.Thetestdescribedinvolvescorrosionreactionsinwhichtheproductsdelineatedefectsitesincoatings.Sincethechemistry,andpropertiesoftheseproductsmaynotresemblethosefoundinnaturalorserviceenvironments,thesetestsarenotrecommendedforpredictionoftheelectricalperformanceofcontactsunlesscorrelationisfirstestablishedwithserviceexperience.Thetestmethoddescribedemploysnitricacid(HNO3)vapouratlowrelativehumidity.Reactionofthegasmixturewithacorrodiblebasemetalatporesitesproducesreactionproductsthatappearasdiscretespotsonthegoldsurface.Individualspotsarecountedwiththeaidofalensorlow-powerstereomicroscope.Thetestmethoddescribedisintendedtobeusedforquantitativedescriptionsofporosity(suchasnumberofporesperunitareaorpercontact)onlyoncoatingsthathaveaporedensitysufficientlylowthatthecorrosionsitesarewellseparatedandcanbereadilyresolved.Asageneralguidelinethiscanbeachievedforporedensitiesuptoabout100persquarecentimetreorper100contacts.Abovethisvaluethetestsareusefulforthequalitativedetectionandcomparisonofporosity.kSIST FprEN ISO 14647:2015

kSIST FprEN ISO 14647:2015

INTERNATIONALSTANDARDISO14647:2000(E)©ISO2000–Allrightsreserved1Metalliccoatings—Determinationofporosityingoldcoatingsonmetalsubstrates—NitricacidvapourtestWARNING:ThisInternationalStandarddoesnotpurporttoaddressallofthesafetyproblems,ifany,associatedwithitsuse.ItistheresponsibilityoftheuserofthisInternationalStandardtoestablishappropriatesafetyandhealthpracticesandtodeterminetheapplicabilityofregulatorylimitationspriortouse.Specificprecautio

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