SIST EN ISO 27874:2008
(Main)Metallic and other inorganic coatings - Electrodeposited gold and gold alloy coatings for electrical, electronic and engineering purposes - Specification and test methods (ISO 27874:2008)
Metallic and other inorganic coatings - Electrodeposited gold and gold alloy coatings for electrical, electronic and engineering purposes - Specification and test methods (ISO 27874:2008)
This International Standard specifies the requirements for electrodeposited gold and gold alloy coatings for electrical, electronic and other engineering applications on metallic and non-metallic substrates. It also specifies test methods for measuring the properties of the coatings. Although this International Standard does not specify the condition, finish or surface roughness of the basis material prior to electroplating, the appearance and serviceability of electroplated gold or gold alloy coatings depends on the condition of the basis material. It is essential that the purchaser specify the surface finish and roughness of the basis material in order to conform to the product requirements. This International Standard does not apply to coatings on threaded articles or to coatings on sheet or strip in non-fabricated form.
Metallische Überzüge - Galvanische Gold- und Goldlegierungsüberzüge für elektrische, elektronische und technische Zwecke - Anforderungen und Prüfverfahren (ISO 27874:2008)
Diese Internationale Norm legt die Anforderung an galvanische Gold- und Goldlegierungs-Überzüge auf metallischen und nichtmetallischen Substraten für elektrische, elektronische und andere technische Anwendungen fest. Sie legt auch die Prüfverfahren zur Bestimmung der Eigenschaften dieser Überzüge fest.
Obgleich diese Internationale Norm Beschaffenheit, Finish und Rauheit des Grundmaterial vor der elektrolytischen Abscheidung nicht festlegt, hängt das Aussehen und die Brauchbarkeit von galvanischen Gold- und Goldlegierungs-Überzügen von der Beschaffenheit des Grundmaterials ab. Es ist wesentlich, dass der Käufer Finish und Rauheit des Grundmaterials festlegt, um dadurch die Anforderungen an das Produkt zu bestätigen.
Diese Internationale Norm gilt nicht für Verbindungselemente mit Gewinden (siehe ISO 4042) oder für Überzüge auf Blechen und Bändern in unbearbeiteter Form.
ANMERKUNG Die Verfahren, auf die sich diese Internationale Norm bezieht bzw. die sie beinhaltet, können die Benutzung gefährlicher Materialien, Betriebsbedingungen oder Einrichtungen erfordern. Diese Norm spricht keine Gesundheits- oder Sicherheits-Vorschriften an, die mit deren Anwendung verbunden sind. Es liegt in der Verantwortung des Anwenders dieser Norm, geeignete Gesundheits- und Sicherheits-Praktiken einzuführen, um alle erforderlichen Vorsichtsmaßnahmen zur Einhaltung nationaler oder regionaler Vorschriften zu erfüllen.
Revêtements métalliques et autres revêtements inorganiques - Dépôts électrolytiques d'or et d'alliages d'or pour usages électrique, électronique et industriels - Spécification et méthodes d'essai (ISO 27874:2008)
L'ISO 27874:2008 spécifie les exigences relatives aux dépôts électrolytiques d'or et d'alliages d'or destinés à des applications électriques, électroniques et d'autres applications industrielles sur des substrats métalliques et non métalliques. Elle spécifie également les méthodes d'essai permettant de mesurer les propriétés des revêtements.
Bien que l'ISO 27874:2008 ne spécifie pas l'état initial, la finition ou la rugosité de surface du matériau de base avant le dépôt électrolytique, l'aspect et l'aptitude à l'usage des dépôts électrolytiques d'or ou d'alliages d'or dépendent de l'état du matériau de base. Il est essentiel que le client spécifie la finition de surface et la rugosité du matériau de base afin de se conformer aux exigences du produit.
L'ISO 27874:2008 ne s'applique ni aux revêtements déposés sur des éléments filetés, ni aux dépôts appliqués sur des tôles ou des bandes à l'état non usiné.
Kovinske prevleke - Galvansko nanašanje prevlek iz zlata in njegovih zlitin za uporabo na področju elektrike, elektronike in inženirstva - Specifikacija in preskusne metode (ISO 27874:2008)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 27874:2008
01-november-2008
.RYLQVNHSUHYOHNH*DOYDQVNRQDQDãDQMHSUHYOHNL]]ODWDLQQMHJRYLK]OLWLQ]D
XSRUDERQDSRGURþMXHOHNWULNHHOHNWURQLNHLQLQåHQLUVWYD6SHFLILNDFLMDLQ
SUHVNXVQHPHWRGH ,62
Metallic and other inorganic coatings - Electrodeposited gold and gold alloy coatings for
electrical, electronic and engineering purposes - Specification and test methods (ISO
27874:2008)
Metallische Überzüge - Galvanische Gold- und Goldlegierungsüberzüge für elektrische,
elektronische und technische Zwecke - Anforderungen und Prüfverfahren (ISO
27874:2008)
Revêtements métalliques et autres revêtements inorganiques - Dépôts électrolytiques
d'or et d'alliages d'or pour usages électrique, électronique et industriels - Spécification et
méthodes d'essai (ISO 27874:2008)
Ta slovenski standard je istoveten z: EN ISO 27874:2008
ICS:
25.220.40 Kovinske prevleke Metallic coatings
SIST EN ISO 27874:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 27874:2008
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SIST EN ISO 27874:2008
EUROPEAN STANDARD
EN ISO 27874
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2008
ICS 25.220.40
English Version
Metallic and other inorganic coatings - Electrodeposited gold
and gold alloy coatings for electrical, electronic and engineering
purposes - Specification and test methods (ISO 27874:2008)
Revêtements métalliques et autres revêtements Metallische Überzüge - Galvanische Gold- und
inorganiques - Dépôts électrolytiques d'or et d'alliages d'or Goldlegierungsüberzüge für elektrische, elektronische und
pour usages électrique, électronique et industriels - technische Zwecke - Anforderungen und Prüfverfahren
Spécification et méthodes d'essai (ISO 27874:2008) (ISO 27874:2008)
This European Standard was approved by CEN on 13 September 2008.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 27874:2008: E
worldwide for CEN national Members.
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SIST EN ISO 27874:2008
EN ISO 27874:2008 (E)
Contents Page
Foreword.3
2
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SIST EN ISO 27874:2008
EN ISO 27874:2008 (E)
Foreword
This document (EN ISO 27874:2008) has been prepared by Technical Committee ISO/TC 107 "Metallic and
other inorganic coatings" in collaboration with 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 March 2009, and conflicting national standards shall be withdrawn at
the latest by March 2009.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 27874:2008 has been approved by CEN as a EN ISO 27874:2008 without any modification.
3
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SIST EN ISO 27874:2008
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SIST EN ISO 27874:2008
INTERNATIONAL ISO
STANDARD 27874
First edition
2008-09-15
Metallic and other inorganic coatings —
Electrodeposited gold and gold alloy
coatings for electrical, electronic and
engineering purposes — Specification
and test methods
Revêtements métalliques et autres revêtements inorganiques — Dépôts
électrolytiques d'or et d'alliages d'or pour usages électrique,
électronique et industriels — Spécification et méthodes d'essai
Reference number
ISO 27874:2008(E)
©
ISO 2008
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
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ii © ISO 2008 – All rights reserved
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Information to be supplied to the electroplater .3
5 Designation . 4
6 Requirements and test methods. 6
7 Sampling. 9
Annex A (normative) Requirements for undercoats. 10
Annex B (normative) Methods of measuring the thickness of gold and gold alloy coatings . 12
Annex C (normative) Adhesion tests . 20
Annex D (normative) Determination of gold content. 22
Bibliography . 24
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SIST EN ISO 27874:2008
ISO 27874:2008(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 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 27874 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,
Subcommittee SC 3, Electrodeposited coatings and related finishes.
This first edition of ISO 27874 cancels and replaces ISO 4523:1985, ISO 4524-1:1985, ISO 4524-4:1985 and
ISO 4524-5:1985, of which it constitutes a technical revision.
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
Introduction
The engineering uses of electrodeposited gold and gold alloy coatings have expanded with the growth of the
electrical and electronic industries. Low voltages and currents, dry circuits and microwave frequencies require
low-resistance interconnection systems, connectors and waveguides. Non-tarnishing, low-resistance gold
coatings were the logical choice for connectors where the stability of contact surfaces was critical. The need to
improve the wear resistance of gold coatings led to the development of new electroplating solutions containing
controlled amounts of metallic and non-metallic additives that either changed the composition or altered the
crystal structure of the coating. The special needs of the printed-circuit industry led to the development of acid
gold electroplating solutions that contained no free cyanide, yielding coatings that are hard, bright and
2
solderable. Formulations for high-speed electroplating up to current densities of 200 A/dm were introduced
for continuous strip, stripe or spot gold and gold alloy coatings.
The high cost of gold metal has led to the development of selective and thickness profile plating techniques to
limit the use of the metal to the active areas only of the components, where the gold is required. Designers will
therefore often specify the area requiring gold electroplating as well as the thickness profile, if required, by
reference to suitably marked drawings.
With the introduction of many new gold electroplating formulations and the proliferation of engineering
applications, the need for technical standards that specify the requirements of electrodeposited gold and gold
alloy coatings, as well as the test methods to ensure that the specified requirements are met, is critical.
Composition, appearance, hardness, thickness, purity, porosity, wear resistance, solderability, electrical
contact resistance, infrared reflectivity and other properties must be controlled to produce high-quality gold
and gold alloy coatings for engineering purposes.
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SIST EN ISO 27874:2008
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SIST EN ISO 27874:2008
INTERNATIONAL STANDARD ISO 27874:2008(E)
Metallic and other inorganic coatings — Electrodeposited gold
and gold alloy coatings for electrical, electronic and
engineering purposes — Specification and test methods
WARNING — This International Standard may not be compliant with some countries’ health, safety
and environmental legislations. It calls for the use of substances and/or procedures that may be
injurious to health if adequate safety measures are not taken. This International Standard does not
address any health hazards, safety or environmental matters, or legislation associated with its use. It
is the responsibility of the user of this International Standard to establish appropriate health, safety
and environmentally acceptable practices and take appropriate action to comply with any national,
regional and/or international regulations. Compliance with this International Standard does not, of
itself, confer immunity from legal obligations.
1 Scope
This International Standard specifies the requirements for electrodeposited gold and gold alloy coatings for
electrical, electronic and other engineering applications on metallic and non-metallic substrates. It also
specifies test methods for measuring the properties of the coatings.
Although this International Standard does not specify the condition, finish or surface roughness of the basis
material prior to electroplating, the appearance and serviceability of electroplated gold or gold alloy coatings
depends on the condition of the basis material. It is essential that the purchaser specify the surface finish and
roughness of the basis material in order to conform to the product requirements.
This International Standard does not apply to coatings on threaded articles or to coatings on sheet or strip in
non-fabricated form.
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 1463, Metallic and oxide coatings — Measurement of coating thickness — Microscopical method
ISO 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the measurement of
thickness
ISO 2080, Metallic and other inorganic coatings — Surface treatment, metallic and other inorganic coatings —
Vocabulary
ISO 2177, Metallic coatings — Measurement of coating thickness — Coulometric method by anodic
dissolution
ISO 2819, Metallic coatings on metallic substrates — Electrodeposited and chemically deposited coatings —
Review of methods available for testing adhesion
ISO 3497, Metallic coatings — Measurement of coating thickness — X-ray spectrometric methods
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
ISO 3543, Metallic and non-metallic coatings — Measurement of thickness — Beta backscatter method
ISO 3868, Metallic and other non-organic coatings — Measurement of coating thicknesses — Fizeau multiple-
beam interferometry method
ISO 3882, Metallic and other inorganic coatings — Review of methods of measurement of thickness
ISO 4516, Metallic and other inorganic coatings — Vickers and Knoop microhardness tests
ISO 4518, Metallic coatings — Measurement of coating thickness — Profilometric method
ISO 4519, Electrodeposited metallic coatings and related finishes — Sampling procedures for inspection by
attributes
ISO 4524-2, Metallic coatings — Test methods for electrodeposited gold and gold alloy coatings — Part 2: Mixed
flowing gas (MFG) environmental tests
ISO 4524-3:1985, Metallic coatings — Test methods for electrodeposited gold and gold alloy coatings — Part 3:
Electrographic tests for porosity
ISO 4524-6, Metallic coatings — Test methods for electrodeposited gold and gold alloy coatings — Part 6:
Determination of the presence of residual salts
ISO 9587, Metallic and other inorganic coatings — Pretreatment of iron or steel to reduce the risk of hydrogen
embrittlement
ISO 9588, Metallic and other inorganic coatings — Post-coating treatments of iron or steel to reduce the risk of
hydrogen embrittlement
ISO 10289, Methods for corrosion testing of metallic and other inorganic coatings on metallic substrates —
Rating of test specimens and manufactured articles subjected to corrosion tests
ISO 10308, Metallic coatings — Review of porosity tests
ISO 12687, Metallic coatings — Porosity tests — Humid sulfur (flowers of sulfur) test
ISO 14647, Metallic coatings — Determination of porosity in gold coatings on metal substrates — Nitric acid
vapour test
IEC 60068-2-20, Environmental testing — Part 2-20: Tests — Test T: Test methods for solderability and
resistance to soldering heat of devices with leads
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2064 and ISO 2080 and the
following apply.
3.1
gold or gold alloy coating
electrodeposited gold or gold alloy having intentional alloying elements in its composition
3.2
double-layer gold or gold alloy coating
gold or gold alloy coating consisting of two discrete layers of differing gold contents
3.3
multilayer gold or gold alloy coating
gold or gold alloy coating consisting of more than two discrete layers of differing gold contents
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
4 Information to be supplied to the electroplater
4.1 Essential information
The following information shall be supplied by the purchaser to the electroplater in writing in the purchase
order or contract, or on engineering drawings:
a) the designation (see Clause 5);
b) the significant surface of the article, indicated, for example, as dimensioned areas on drawings or by the
provision of suitably marked samples;
c) the nature, condition and finish of the basis metal if they are likely to affect the serviceability and/or the
appearance of the coating (see Clause 1);
d) the position on the surface of any unavoidable defects, such as rack marks (see 6.2);
e) the finish required, for example bright, dull or another type, preferably accompanied by approved samples
of the finish (see 6.2);
f) the method of porosity testing to be used and the permitted number and location of acceptable pores
(see 6.4);
g) the tensile strength of the part and the requirements for any heat treatment prior to, or after, electroplating
(see 6.7 and 6.8);
h) sampling methods, acceptance levels and any other inspection requirements if different from those
specified in ISO 4519 (see Clause 7);
i) the requirements for coating thickness, including positions of measurement as indicated on dimensioned
drawings (see 6.3);
j) the requirements for adhesion testing (see 6.9).
4.2 Additional information
The following additional information may be required and, if so, shall be specified by the purchaser in writing,
for example in the contract or purchase order, or on drawings:
a) the composition of the coating and details of intentional alloying elements and undesirable impurities
(see 6.6);
b) any special cleaning procedures to be used;
c) any special requirements for undercoats (see 6.15 and Annex A);
d) any requirements for the composition and thickness of each layer in double or multilayer coatings
(see Clause 3);
e) the electrical properties of the coating and the methods of test to be used (see 6.10);
f) the microhardness of the coating and the test method to be used (see 6.11);
g) any requirements for solderability and the test method to be used (see 6.12);
h) any requirements for wear resistance and the test method to be used (see 6.13);
i) the ductility of the coating and the method of test to be used (see 6.14);
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ISO 27874:2008(E)
j) any requirements for the freedom from surface contamination of the finished articles (see 6.16);
k) the agreed mean density of a gold alloy coating if the thickness measurement method requires a density
correction (see Annex B);
l) any requirements for accelerated-corrosion testing (see 6.5);
m) any other requirements, such as a residual-salts test, (see 6.16).
5 Designation
5.1 General
The designation shall appear on engineering drawings, in the purchase order, in the contract or in the detailed
product specification.
The designation specifies, in the following order, the basis metal, the specific alloy (optional), stress relief
requirements, the type(s) and thickness(s) of undercoats (when present), the thickness and composition of the
gold or gold alloy coating or coatings (when double or multilayer coatings are specified), and supplementary
treatments such as heat treatment to reduce susceptibility to hydrogen embrittlement.
5.2 Designation specifications
The designation shall comprise the following:
a) the term, “electrodeposited coating”;
b) the number of this International Standard (ISO 27874);
c) a hyphen;
d) the chemical symbol of the basis metal (see 5.3);
e) a solidus (/);
f) if appropriate, the chemical symbol for an undercoat metal followed, if necessary, by a number giving the
thickness of the undercoat in micrometres (see 6.15 and Annex A);
g) a solidus (/);
h) the chemical symbol for gold, Au, or the standard designation for a gold alloy, including the symbol of the
alloying element and a figure in parentheses giving the mean content of that element expressed as a mass
fraction in percent to one decimal place;
i) a number giving the minimum local thickness requirement for the gold or gold alloy coating in
micrometres;
j) for double and multilayer gold coatings, repeat h) and i), followed by a solidus (/), for each subsequent
gold or gold alloy coating required.
5.3 Designating the basis material
The basis material shall be designated by its chemical symbol or the chemical symbol of its principal
constituent if an alloy, for example:
Fe for iron and steel;
Zn for zinc alloys;
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ISO 27874:2008(E)
Cu for copper and copper alloys;
Al for aluminium and aluminium alloys.
In the case of non-metallic materials, the letters NM shall be used.
A specific alloy shall be identified by its standard designation, for example its UNS number or the local,
national, equivalent placed between the symbols < >.
For example, Fe is the UNS designation for a particular high-strength steel (see Reference [5] in
the Bibliography).
5.4 Designation of heat treatment requirements
The heat treatment requirements shall be in brackets and designated as follows:
a) the letters SR for stress relief heat treatment prior to electroplating, the letters ER for hydrogen
embrittlement relief heat treatment after electroplating, and the letters HT for heat treatment for other
purposes;
b) in parentheses, the minimum temperature, in °C;
c) the duration of the heat treatment in hours, for example SR(210)1 designates stress relief heat treatment
at 210 °C for 1 h.
When heat treatment prior to or after electrodeposition is specified, the requirements shall be included in the
designation as shown in the examples (see 5.5).
The structure and composition of gold and gold alloy coatings may be modified and the coating properties
substantially altered by heat treatment. Designers should be aware of these effects before specifying gold
coatings on high-tensile-strength basis material.
5.5 Examples
A pure gold coating, Au, with a minimum thickness of 5 µm on nickel-electroplated steel, Fe/Ni, will have the
following designation:
Electrodeposited coating ISO 27874 – Fe/Ni/Au5
An alloy coating containing 98,0 % gold and 2 % silver, AuAg(2,0), with a minimum thickness of 5 µm on a zinc
alloy, Zn, with copper and nickel undercoats will have the following designation:
Electrodeposited coating ISO 27874 – Zn/Cu/Ni/AuAg(2,0)5
An alloy coating containing 99,5 % gold and 0,2 % nickel, AuNi(0,2), with a minimum thickness of 0,5 µm
deposited over a pure-gold coating, Au, with a minimum thickness of 1 µm on a Cu alloy will have the
following designation:
Electrodeposited coating ISO 27874 – Cu/Au1/AuNi(0,2)0,5
A pure-gold coating with a minimum thickness of 5 µm, Au5, deposited over a copper undercoat that is 5 µm
thick, Cu5, on a steel that has an ultimate tensile strength of 1 200 MPa and is heat-treated prior to electroplating
for stress relief at 200 °C for 3 h, SR(200)3, and after electroplating to reduce the risk of hydrogen
embrittlement at 190 °C for 12 h, ER(190)12, will have the following designation:
Electrodeposited coating ISO 27874 – Fe/SR(200)3/Cu5/Au5ER(190)12
The designation describes the heat treatment and electroplating steps in the order in which they are
performed. The standard designation of the basis material could be placed after the chemical symbol, Fe, in
the above example. It is especially important to know the standard designation of a metal or alloy that is
difficult to prepare for electroplating and that is susceptible to hydrogen embrittlement.
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SIST EN ISO 27874:2008
ISO 27874:2008(E)
6 Requirements and test methods
6.1 General
Gold and gold alloy coatings normally consist of a single layer of gold metal, usually with a strike undercoat of
unspecified thickness, but double or multilayer coatings may be specified by the purchaser [see 4.2 c)].
6.2 Appearance
Although this International Standard does not specify the condition, finish or surface roughness of the basis
material prior to electroplating, the appearance of electroplated gold and gold alloy coatings depends on the
condition of the basis material (see the Bibliography for surface preparation methods). Over the significant
surface, the electroplated article shall be free from clearly visible blisters, pits, roughness, cracks and
uncoated areas other than those that arise from defects in the basis material. The electroplated article shall be
free from extraneous soil and mechanical damage. On articles where a contact mark is unavoidable, its
position and extent shall be specified by the purchaser [see 4.1 d)].
In the case of selectively plated articles, the degree and extent of discoloration at the boundary between the
areas that have been electroplated and those that are not electroplated shall be specified on the product
drawing.
If required, a preliminary sample with the required standard of finish shall be supplied or approved by the
purchaser [see 4.1 e)].
The types of article which are selectively electroplated with gold are commonly also selectively electroplated
with other metals, such as a nickel undercoat or solderable tin alloy coating. Agreements on visual standards
will thus extend to all such areas and boundaries. It is therefore essential that such parameters be specified
on the product drawing.
6.3 Thickness
The thickness of the coating specified in the designation shall be the minimum local thickness. The minimum
local thickness of the coating shall be measured within the reference area or at a site specified on the
component drawing. The minimum thickness of the gold or gold alloy coating shall be that specified by the
purchaser.
One or more of the methods given in Annex B shall be used to measure the thickness of the gold or gold alloy
coating.
A profile of the minimum-thickness distribution may alternatively be specified on suitably prepared drawings.
Thicknesses of gold and gold alloy coatings commonly specified for electrical, electronic or engineering
applications are given in Table 1.
Table 1 — Examples of commonly specified thicknesses of gold and gold alloy coatings
for various applications
Minimum thickness
Application
µm
Solderability retention, low-reliability electrical contacts 0,1
Medium-reliability electrical connector and switch contacts 0,25
(electroplated acid gold alloy)
Semiconductor bonding (pure gold) 0,5
High-reliability consumer electrical c
...
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