ASTM B281-88(2019)e1
(Practice)Standard Practice for Preparation of Copper and Copper-Base Alloys for Electroplating and Conversion Coatings
Standard Practice for Preparation of Copper and Copper-Base Alloys for Electroplating and Conversion Coatings
SIGNIFICANCE AND USE
3.1 The proper preparation of copper and copper alloy surfaces for electroplating, conversion coating, or autocatalytic plating is often critical to the performance of the coatings.
3.2 This practice outlines procedures required to produce satisfactory coatings on surfaces of copper and copper alloy surfaces.
SCOPE
1.1 This practice is intended to serve as a guide for the proper preparation of copper and its alloys for electroplating and conversion coating. This practice is also suitable for use before autocatalytic plating. Only alloys containing at least 50 mass % copper are considered within the scope of this practice.
1.2 The wide variety of methods of mechanical finishing are not considered strictly as preparation for electroplating or conversion coating and consequently are described only briefly.
1.3 Details of electroplating and subsequent treatments for applying conversion coatings are not within the scope of this practice.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 6.5.2.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: B281 − 88 (Reapproved 2019)
Standard Practice for
Preparation of Copper and Copper-Base Alloys for
Electroplating and Conversion Coatings
This standard is issued under the fixed designation B281; 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 U.S. Department of Defense.
ε NOTE—The name and designation of the ASTM standard cited in 2.1 and Note 3 were updated editorially in May 2019.
1. Scope 3. Significance and Use
1.1 This practice is intended to serve as a guide for the
3.1 The proper preparation of copper and copper alloy
proper preparation of copper and its alloys for electroplating
surfaces for electroplating, conversion coating, or autocatalytic
and conversion coating. This practice is also suitable for use
plating is often critical to the performance of the coatings.
before autocatalytic plating. Only alloys containing at least 50
3.2 This practice outlines procedures required to produce
mass %copperareconsideredwithinthescopeofthispractice.
satisfactory coatings on surfaces of copper and copper alloy
1.2 The wide variety of methods of mechanical finishing are
surfaces.
not considered strictly as preparation for electroplating or
conversion coating and consequently are described only
4. Process Chemicals
briefly.
4.1 All process chemicals are of technical grade or better.
1.3 Details of electroplating and subsequent treatments for
Acid solutions are prepared from grade chemicals as listed in
applying conversion coatings are not within the scope of this
Appendix X1.
practice.
4.2 Purity of Water—High quality water is not normally
1.4 This standard does not purport to address all of the
required to make up and maintain the solutions utilized in this
safety concerns, if any, associated with its use. It is the
practice. If reused or recycled water from waste treatment
responsibility of the user of this standard to establish appro-
processes or from other in-plant sources is to be used, it should
priate safety, health, and environmental practices and deter-
be relatively free of chromium salts, oil, wetting agents, or
mine the applicability of regulatory limitations prior to use.
insoluble materials. Excessively hard water can decrease the
For a specific hazard statement, see 6.5.2.
life and performance of many cleaning solutions and make
1.5 This international standard was developed in accor-
parts more difficult to rinse completely.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5. General Considerations
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 Removal of Oxides—Oxides can be removed from as
Barriers to Trade (TBT) Committee.
fabricated, annealed, or heat-treated alloys by abrasive meth-
ods such as tumbling, burnishing, and emery set-up wheel
2. Referenced Documents
polishing and by chemical methods, such as deoxidizing
2.1 ASTM Standards: solutions, bright dips, and cyanide dips. The choice of method
B322 Guide for Cleaning Metals Prior to Electroplating
is dependent on the resultant surface finish required, amount of
oxide to be removed, and the end-use properties of the article
finished.
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
5.2 CastingsandForgings—Castingsandforgingsrequiring
Pre Treatment.
abrasive methods to produce a desired surface finish do not
Current edition approved April 1, 2019. Published May 2019. Originally
necessarily need pickling or bright dipping. If pickled, bright
approvedin1953.Lastpreviouseditionapprovedin2013asB281 – 88(2013).DOI:
10.1520/B0281-88R19E01.
dipped, or deoxidized, however, castings and other porous
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
parts should be thoroughly rinsed between operations to avoid
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
or minimize staining or stain spots. Castings or forgings
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. processed in solutions containing wetting agents, which are in
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B281 − 88 (2019)
many proprietary products or which may be added by the typical tumble cleaner is listed in Appendix X1. Proprietary
individual, usually require greater care in rinsing. cleaners are available and are generally considered preferable.
5.3 Stampings and Drawn Products—Stampings and drawn
6.5 Tarnish and Stain Removal, Deoxidizing, and Neutral-
work follow the same rule as castings and forgings except, for izing:
economy considerations, it may be advisable to pickle or
6.5.1 Acid Dipping—After the work has been thoroughly
deoxidize before abrasive finishing if heavy oxides are present.
cleaned and rinsed, it must be acidified to neutralize any
residual alkali before it enters an electroplating bath. Thus,
5.4 Cold-Headed and Progressive Die Products—Cold-
before nickel, copper, tin, chromium, and similar plating
headed products and progressive die products often require
solutions, an acid dip is used. The most common dips used are
relief annealing to avoid subsequent season cracking.
sulfuric acid, 50 mL⁄L to 100 mL⁄L by volume, or hydrochlo-
5.5 Screw Machine Products—Screw machine products
ric acid, 100 mL⁄L to 200 mL⁄L by volume. Fluoboric acid,
may be readily electroplated with only mild cleaning and acid
50 mL⁄L to 100 mL/L by volume, can be used before fluobo-
dipping as they are produced from the machines. Abrasive
rate electroplating solutions. These solutions are maintained at
methods may be applied as appropriate before cleaning and
roomtemperature.Leadedcopperalloysforminsolublesaltsin
acid dipping.
either sulfuric or hydrochloric acid, and therefore should be
pickled in fluoboric acid, 20 mL⁄L to 50 mL⁄L by volume, or
6. Preparation for Electroplating and Conversion
nitric acid, 100 mL⁄L to 200 mL⁄L by volume.
Coating
6.5.2 Cyanide Dipping—After the work has been cleaned,
acid pickled, or acid dipped, and thoroughly rinsed, it is
6.1 Outlines of Typical Preparatory Cycles:
6.1.1 Vapor degrease or alkaline clean or emulsion soak sometimesimmersedina15to45 g⁄Lsodiumcyanidesolution
to remove slight tarnish. This step is more common if the first
clean, or tumble clean,
6.1.2 Rinse, electroplating solution also contains cyanide. (Warning—One
should provide adequate rinsing before and after any cyanide-
6.1.3 Alkaline electroclean,
containing solution before going into an acid solution.)
6.1.4 Rinse,
6.1.5 Acid dip,
NOTE6—Whenprocessingpartscontainingleadasanalloyconstituent,
6.1.6 Rinse, and
such as free-machining brass, care should be taken not to allow lead to
6.1.7 Electroplate or conversion coat in an acid solution. accumulate in a cyanide solution beyond 50 mg⁄L as Pb.
6.5.3 Deoxidizing and Bright Dipping:
NOTE 1—A bright dip, electropolish, or deoxidization may be added
after step 6.1.4 or 6.1.2.4 followed by two agitated and running rinses
6.5.3.1 Deoxidizing is usually performed to activate the
prior to step 6.1.5.
surface of the part by the removal of the oxide coating. Strong
NOTE 2—If chromium compounds are used in the bright dip or
oxidizing solutions such as mixtures of sulfuric acid and
alternatives in Note 1, additional steps will be required to ensure complete
hydrogen peroxide are used as pickling agents. Most of these
chromium removal from surfaces before any plating process.
compositions are proprietary.
NOTE 3—Additional information on procedures for cleaning of copper
or copper alloys prior to electroplating may be found in Guide B322.
6.5.3.2 Bright dipping is primarily used to improve the
surface luster of the work. It also serves as a deoxidizing
6.2 Precleaning—Solvent or solvent-alkali emulsion-soak
solution. While proprietary processes are available one non-
cleaners can be used if the parts being electroplated can be
proprietary composition which can produce good surface luster
rinsed easily and completely; otherwise, mild alkaline cleaners
(not mirror brightness) is included in Appendix X1. The bright
and vapor degreasing should be used.
dipped parts should be rinsed thoroughly by immersion in
6.3 Electrocleaning—To produce the chemically clean sur-
several water rinses with constant agitation. A mild alkaline
face required for
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