ASTM B281-88(2008)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B281 − 88 (Reapproved2008)
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 Department of Defense.
1. Scope 3.2 This practice outlines procedures required to produce
satisfactory coatings on surfaces of copper and copper alloy
1.1 This practice is intended to serve as a guide for the
surfaces.
proper preparation of copper and its alloys for electroplating
and conversion coating. This practice is also suitable for use
4. Process Chemicals
before autocatalytic plating. Only alloys containing at least 50
mass %copperareconsideredwithinthescopeofthispractice.
4.1 All process chemicals are of technical grade or better.
Acid solutions are prepared from grade chemicals as listed in
1.2 Thewidevarietyofmethodsofmechanicalfinishingare
Appendix X1.
not considered strictly as preparation for electroplating or
conversion coating and consequently are described only
4.2 Purity of Water—High quality water is not normally
briefly.
required to make up and maintain the solutions utilized in this
1.3 Details of electroplating and subsequent treatments for practice. If reused or recycled water from waste treatment
processes or from other in-plant sources is to be used, it should
applying conversion coatings are not within the scope of this
practice. be relatively free of chromium salts, oil, wetting agents, or
insoluble materials. Excessively hard water can decrease the
1.4 This standard does not purport to address all of the
life and performance of many cleaning solutions and make
safety concerns, if any, associated with its use. It is the
parts more difficult to rinse completely.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. General Considerations
bility of regulatory limitations prior to use. For a specific
hazard statement, see 6.5.2.
5.1 Removal of Oxides—Oxides can be removed from as
fabricated, annealed, or heat-treated alloys by abrasive meth-
2. Referenced Documents
ods such as tumbling, burnishing, and emery set-up wheel
polishing and by chemical methods, such as deoxidizing
2.1 ASTM Standards:
solutions, bright dips, and cyanide dips. The choice of method
D322 Test Method for Gasoline Diluent in Used Gasoline
is dependent on the resultant surface finish required, amount of
Engine Oils by Distillation
oxide to be removed, and the end-use properties of the article
finished.
3. Significance and Use
5.2 CastingsandForgings—Castingsandforgingsrequiring
3.1 The proper preparation of copper and copper alloy
abrasive methods to produce a desired surface finish do not
surfaces for electroplating, conversion coating, or autocatalytic
plating is often critical to the performance of the coatings. necessarily need pickling or bright dipping. If pickled, bright
dipped, or deoxidized, however, castings and other porous
parts should be thoroughly rinsed between operations to avoid
or minimize staining or stain spots. Castings or forgings
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
processed in solutions containing wetting agents, which are in
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
Pre Treatment. many proprietary products or which may be added by the
Current edition approved Aug. 1, 2008. Published September 2008. Originally
individual, usually require greater care in rinsing.
approved in 1953. Last previous edition approved in 2001 as B281 – 88 (2001).
DOI: 10.1520/B0281-88R08.
5.3 Stampings and Drawn Products—Stampings and drawn
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
work follow the same rule as castings and forgings except, for
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
economy considerations, it may be advisable to pickle or
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. deoxidize before abrasive finishing if heavy oxides are present.
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B281 − 88 (2008)
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. sulfuricacid,50mL/Lto100mL/Lbyvolume,orhydrochloric
acid, 100 mL/L to 200 mL/L by volume. Fluoboric acid, 50
5.5 Screw Machine Products—Screw machine products
mL/L to 100 mL/L by volume, can be used before fluoborate
may be readily electroplated with only mild cleaning and acid
electroplating solutions. These solutions are maintained at
dipping as they are produced from the machines. Abrasive
roomtemperature.Leadedcopperalloysforminsolublesaltsin
methods may be applied as appropriate before cleaning and
either sulfuric or hydrochloric acid, and therefore should be
acid dipping.
pickled in fluoboric acid, 20 mL/L to 50 mL/L by volume, or
nitric acid, 100 mL/L to 200 mL/L by volume.
6. Preparation for Electroplating and Conversion
6.5.2 Cyanide Dipping—After the work has been cleaned,
Coating
acid pickled, or acid dipped, and thoroughly rinsed, it is
6.1 Outlines of Typical Preparatory Cycles:
sometimesimmersedina15to45g/Lsodiumcyanidesolution
6.1.1 Vapor degrease or alkaline clean or emulsion soak
to remove slight tarnish. This step is more common if the first
clean, or tumble clean,
electroplating solution also contains cyanide. (Warning—One
6.1.2 Rinse,
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,
NOTE6—Whenprocessingpartscontainingleadasanalloyconstituent,
6.1.5 Acid dip,
such as free-machining brass, care should be taken not to allow lead to
6.1.6 Rinse, and
accumulate in a cyanide solution beyond 50 mg/L as Pb.
6.1.7 Electroplate or conversion coat in an acid solution.
6.5.3 Deoxidizing and Bright Dipping :
NOTE 1—A bright dip, electropolish, or deoxidization may be added
6.5.3.1 Deoxidizing is usually performed to activate the
after step 6.1.4 or 6.1.2.4 followed by two agitated and running rinses
surface of the part by the removal of the oxide coating. Strong
prior to step 6.1.5.
oxidizing solutions such as mixtures of sulfuric acid and
NOTE 2—If chromium compounds are used in the bright dip or
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
6.5.3.2 Bright dipping is primarily used to improve the
or copper alloys prior to electroplating may be found in Practice D322.
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
proprietarycompositionwhichcanproducegoodsurfaceluster
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 electroplating or subsequent coatings, an solution may be employed to neutralize residual acids before
electrolytic cleaner may be used with the part as the anode or immersion in any cyanide-containing solution. An excess of
cathode. Anodic cleaning, particularly of brass, may cause hydrochloric acid in the bright dip composition must be
slight tarnishing or etching if applied for a prolonged time avoided; otherwise, a dull finish will result.
(more than a few seconds) or at too high or too low an
7. Striking
operating temperature. A contaminated cathodic cleaner may
7.1 Copper Strike—In order to prevent peeling, a
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