ASTM B488-01(2010)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: B488 – 01 (Reapproved 2010)
Standard Specification for
Electrodeposited Coatings of Gold for Engineering Uses
This standard is issued under the fixed designation B488; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Editorially corrected throughout in March 2011.
1. Scope B254 Practice for Preparation of and Electroplating on
Stainless Steel
1.1 This specification covers requirements for electrodepos-
B281 Practice for Preparation of Copper and Copper-Base
ited gold coatings that contain not less than 99.00 mass % gold
Alloys for Electroplating and Conversion Coatings
and that are used for engineering applications.
B322 Guide for Cleaning Metals Prior to Electroplating
1.2 Specifically excluded from this specification are auto-
B343 Practice for Preparation of Nickel for Electroplating
catalytic, immersion, and vapor deposited gold coatings.
with Nickel
1.3 Gold coatings conforming to this specification are em-
B374 Terminology Relating to Electroplating
ployed for their corrosion and tarnish resistance (including
B481 Practice for Preparation of Titanium and Titanium
resistance to fretting corrosion and catalytic polymerization),
Alloys for Electroplating
bondability, low and stable contact resistance, solderability,
B482 Practice for Preparation of Tungsten and Tungsten
and infrared reflectivity. Several types of coatings, differing in
Alloys for Electroplating
gold purity and hardness, are covered by this specification.
B487 Test Method for Measurement of Metal and Oxide
1.4 The values stated in SI units are to be regarded as the
CoatingThicknessbyMicroscopicalExaminationofCross
standard. Values provided in parentheses are for information
Section
only.
B489 Practice for Bend Test for Ductility of Electrodepos-
1.5 The following hazards caveat pertains only to the test
ited and Autocatalytically Deposited Metal Coatings on
methods section, Section 9, of this specification: This standard
Metals
does not purport to address all of the safety concerns, if any,
B499 Test Method for Measurement of Coating Thick-
associated with its use. It is the responsibility of the user of this
nessesbytheMagneticMethod:NonmagneticCoatingson
standard to establish appropriate safety and health practices
Magnetic Basis Metals
and determine the applicability of regulatory limitations prior
B504 Test Method for Measurement of Thickness of Me-
to use.
tallic Coatings by the Coulometric Method
2. Referenced Documents
B507 Practice for Design ofArticles to Be Electroplated on
Racks
2.1 ASTM Standards:
B542 Terminology Relating to Electrical Contacts and
B183 Practice for Preparation of Low-Carbon Steel for
Their Use
Electroplating
B558 Practice for Preparation of NickelAlloys for Electro-
B242 Guide for Preparation of High-Carbon Steel for Elec-
plating
troplating
B567 Test Method for Measurement of Coating Thickness
B253 Guide for Preparation of Aluminum Alloys for Elec-
by the Beta Backscatter Method
troplating
B568 Test Method for Measurement of Coating Thickness
by X-Ray Spectrometry
This specification is under the jurisdiction of ASTM Committee B08 on
B571 Practice for Qualitative Adhesion Testing of Metallic
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
Coatings
B08.08.02 on Precious Metal Coatings.
B578 Test Method for Microhardness of Electroplated
Current edition approved Nov. 1, 2010. Published November 2010. Originally
approvedin1968.Lastpreviouseditionapprovedin2006asB488 – 01(2006).DOI:
Coatings
10.1520/B0488-01R10E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B488 – 01 (2010)
B602 Test Method for Attribute Sampling of Metallic and 4. Classification
Inorganic Coatings
4.1 Types of Coatings—A coating shall be specified by a
B678 Test Method for Solderability of Metallic-Coated
combination of the following:
Products
4.1.1 Type, characterizing minimum purity in accordance
B697 Guide for Selection of Sampling Plans for Inspection
with 4.2.1,
of Electrodeposited Metallic and Inorganic Coatings
4.1.2 Code, designating Knoop hardness in accordance with
B735 Test Method for Porosity in Gold Coatings on Metal
4.2.3, and
Substrates by Nitric Acid Vapor
4.1.3 a numeral designating thickness in micrometres in
B741 Test Method for Porosity In Gold Coatings On Metal
3 accordance with 4.3.
Substrates By Paper Electrography
4.2 Purity and Hardness:
B748 Test Method for Measurement of Thickness of Me-
tallic Coatings by Measurement of Cross Section with a 4.2.1 Purity—The issue of this standard establishes a new
Scanning Electron Microscope ASTM Type designation, which is identical to the original
B762 Test Method of Variables Sampling of Metallic and standard (MIL-G-45204, which is now MIL-DTL-45204),
established for electrodeposited gold and is outlined in the
Inorganic Coatings
following table.
B765 Guide for Selection of Porosity and Gross Defect
Tests for Electrodeposits and Related Metallic Coatings Mass Percent Gold, Minimum, New ASTM MIL-DTL- Old ASTM
Excluding Potassium, Carbon & Type 45204 Type Type
B799 Test Method for Porosity in Gold and Palladium
Nitrogen
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
99.70 I I 2
99.00 II II 3
B809 Test Method for Porosity in Metallic Coatings by
99.90 III III 1
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
D1125 Test Methods for Electrical Conductivity and Resis- NOTE 1—It is commonly accepted that a gold purity of 99.7 % is
defined as no more than 0.3 % of total codeposited metallic components,
tivity of Water
excludingpotassiumandsodium.Likewise,99.9 %purityisrecognizedto
D3951 Practice for Commercial Packaging
mean no more than 0.1 % of total codeposited metal impurities, excluding
F390 Test Method for Sheet Resistance of Thin Metallic
potassium and sodium. Almost all gold electrodeposits will contain
Films With a Collinear Four-Probe Array
potassium, carbon and nitrogen that are occluded or precipitated in the
2.2 U.S. Government Standards:
deposit.InthecaseofTypeIgold,theoccludedpotassiumhasbeenshown
,
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to improve durability and is desirable for that reason.
MIL-DTL-45204 Gold Plating, Electrodeposited
MIL-STD-1916 DOD Preferred Methods forAcceptance of
4.2.2 Gold purity is calculated by subtraction of the sum of
Product
all non-gold metals in mass %, excluding potassium (K) and
2.3 ANSI/ASQC Standard:
sodium (Na), from 100 %. The presence of Carbon (C),
Nitrogen (N), Hydrogen (H), Na, and K contained in the
ANSI/ASQC Z1.4 Sampling Procedures and Tables for
electrodeposit are not included in the calculation.
Inspection by Attributes
4.2.3 Hardness—Hardness values shall be specified by
3. Terminology ASTM Code. The military standard designation of Grade is
included for reference.
3.1 Definitions—For definitions of terms used in this speci-
Knoop Hardness Range ASTM Code MIL-DTL-
ficationrefertoTerminologiesB374orB542,B374,andB542.
3.2 Definitions of Terms Specific to This Standard:
90 HK maximum A A
91–129 HK BB
3.2.1 significant surfaces—defined as those normally vis-
90–200 HK (see Note 2) .
ible (directly or by reflection) or essential to the serviceability
130–200 HK CC
or function of the article. Can be the source of corrosion
>200 HK DD
products or tarnish films that interfere with the function or
NOTE 2—ASTM Code B has previously been specified for hardness
desirable appearance of the article. The significant surfaces
grade 90–200. This hardness grade has been eliminated and replaced with
shall be indicated on the drawings of the parts or by the
hardness grade 91–129 in accordance with MIL-DTL-45204.
provision of suitably marked samples.
4.2.4 Relationship Between Purity and Hardness—The fol-
3.2.2 underplating—a metallic coating layer between the
lowing combinations of purity and hardness ranges are repre-
basis metal or substrate and the topmost metallic coating. The
sentative of good commercial practice:
thickness of an underplating is usually greater than 1 µm (40
New ASTM Old ASTM Type Code
µin.), in contrast to a strike or flash, which is thinner.
I 2 A, B and C
II 3 B, C and D
III 1 A only
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:// Whitlaw, K. J., Souter, J.W., Trans. Inst. Metal Fin., “The Role of Codeposited
dodssp.daps.dla.mil. Elements in Gold Plated Contacts,” 1984, 62(1), pp. 29–31.
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Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., Whitlaw, K. J., Souter, J., Wright, I.S., Nottingham, M., Electrical Contacts,
th.
4th Floor, New York, NY 10036, http://www.ansi.org. “Wear Properties of High Speed Gold Electrodeposits,” (1984), 30 pp. 33–45.
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B488 – 01 (2010)
4.3 Thickness—Thickness shall be specified by an Arabic the appearance and performance of the deposit, despite the
numeral that designates the minimum linear thickness in observance of the best plating practice. Any such defects on
micrometres. Examples of commonly specified thicknesses are significant surfaces shall be brought to the attention of the
shown in Table 1. purchaser.
4.3.1 See 7.4.2 for thickness tolerances. 6.2.3 The basis metal shall be subject to such cleaning
4.3.2 Insteadofspecifyingthethicknessinmicrometres,the procedures as are necessary to ensure a satisfactory surface for
purchaser may specify the mass of gold per unit area (coating subsequent electroplating (see Practices B183, B242, Guide
weight) in milligrams per square centimeter. Unless otherwise B253, Practices B254, B281, B322, B343, B481, B482, and
specified, the density of gold is assumed to be 19.3 g/cm for B558).
Type III and 17.5 g/cm for Type I and Type II. 6.2.4 Proper preparatory procedures and thorough cleaning
of the basis metal are essential for satisfactory adhesion and
NOTE 3—The density of Type III gold coatings will be less than or
3 3 performance of these coatings.The surface must be chemically
equal to 19.3 g/cm , but not less than 18.5 g/cm .
clean and continuously conductive, that is, without inclusions
NOTE 4—Whensignificantsurfacesareinvolvedonwhichthespecified
thickness of deposit cannot readily be controlled, such as threads, holes, or other contaminants. They must be smooth and as free of
deep recesses, bases of angles, and similar areas, the purchaser and the
scratches, gouges, nicks, and similar imperfections as possible.
supplier should recognize the necessity for either thicker deposits on the
NOTE 5—A metal finisher can often remove defects through special
more accessible surfaces or for special racking. Special racks may involve
treatments such as grinding, polishing, abrasive blasting, chemical treat-
the use of conforming, auxiliary, bipolar electrodes, or nonconducting
ments, and electropolishing. However, these may not be normal in the
shields.
treatment steps preceding the plating and a special agreement is indicated.
5. Ordering Information
6.3 Ifrequired(see5.1.7),steelpartswithahardnessgreater
5.1 To make the application of this standard complete, the
than 31 HRC shall be given a suitable stress relief heat
purchaser needs to supply the following information to the
treatmentpriortoplating.Suchstressreliefshallnotreducethe
supplier in the purchase order or other governing document.
hardness to a value below the specified minimum. Acid
5.1.1 The name, designation, and date of issue of this
pickling of high strength steels shall be avoided.
specification.
6.3.1 The coating shall be applied after all basis metal heat
5.1.2 Classification: Type, Code, and thickness (or mass per
treatments and mechanical operations on significant surfaces
unit area) (see Section 4).
have been completed.
5.1.3 Presence and thickness of underplating, if required
6.4 Racking—Parts should be positioned so as to allow free
(see 3.2.2).
circulation of solution over all surfaces.The location of rack or
5.1.4 Significant surfaces shall be specified (see 3.2.1). wire marks in the coating shall be agreed upon between the
5.1.5 Requirement, if any, for performance testing such as
purchaser and the supplier.
porosity testing (see 9.6), solderability testing (see Appendix 6.5 Plating Process:
X4), ductility testing (see 9.7), etc.
6.5.1 Nickel Underplating—For thickness Classes except
5.1.6 If the substrate is one that requires a nickel underplat-
5.0, a nickel underplating shall be applied before the gold
ing (see 6.5.1 and Appendix X6).
coating when the product is made from copper or copper alloy.
5.1.7 Whether or not stress relief has been or is to be done
Nickel underplatings are also applied for other reasons (see
(steel parts only).
Appendix X6).
5.1.8 Sampling plan employed (see Section 8).
NOTE 6—When the thickness of the nickel underplate has a detrimental
impact on the mechanical properties or bondability of the substrate, the
6. Manufacture
nickel thickness may be reduced to a non-detrimental level as specified by
6.1 Any process that provides an electrodeposit capable of
the purchaser.
meeting the specified requirements is acceptable.
NOTE 7—In certain instances in which high-frequency analog signals
6.2 Substrate: are employed, such as in wave guides, the magnetic properties of nickel
may attenuate the signal.
6.2.1 The surface condition of the basis metal should be
NOTE 8—In applications in which forming or flaring operations are to
specified and should meet this specification prior to the plating
be applied to the plated component, a ductile nickel electrodeposit should
of the parts.
be specified.
6.2.2 Defects in the surface of the basis metal such as
6.5.2 Strikes—It is recommended to apply a gold strike to
scratches, porosity, pits, inclusions, roll and die marks, laps,
the underplate or substrate, except if the latter is silver or
cracks, burrs, cold shuts, and roughness may adversely affect
platinum, prior to applying the gold top coating.
6.5.3 Plating—Good practice calls for parts to be electri-
TABLE 1 Coating Thickness
cally connected when entering the gold plating solution. A
Class Minimum Thickness, µm
minimum o
...