ASTM B480-88(2022)

Standard Guide for Preparation of Magnesium and Magnesium Alloys for Electroplating

SIGNIFICANCE AND USE
3.1 Metals are electroplated on magnesium for various purposes: solderability, RF grounding, hermetic sealing, wear resistance, corrosion resistance, appearance, and electrical conductivity, for example. Because magnesium is covered with a naturally occurring oxide film, usual procedures for the preparation of metals for autocatalytic or electrolytic plating cannot be used.
SCOPE
1.1 This guide describes two processes used for plating on magnesium and magnesium alloys: direct electroless nickel plating and zinc immersion. Some users report that the direct electroless nickel procedure does not produce quite as high a level of adhesion as zinc immersion.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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 specific hazard statements, see 5.1.1 and 5.2.9.2.  
1.4 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

• Status: Published
• Publication Date: 30-Apr-2022
• ICS: 25.220.10 - Surface preparation
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.02 - Pre Treatment

Relations

• Refers: ASTM B322-99(2009) - Standard Guide for Cleaning Metals Prior to Electroplating
• Effective Date: 01-Sep-2009
• Refers: ASTM B322-99(2004) - Standard Guide for Cleaning Metals Prior to Electroplating
• Effective Date: 01-Oct-2004
• Refers: ASTM B322-99 - Standard Guide for Cleaning Metals Prior to Electroplating
• Effective Date: 10-Nov-1999

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.
Designation: B480 − 88 (Reapproved 2022)
Standard Guide for
Preparation of Magnesium and Magnesium Alloys for
Electroplating
This standard is issued under the fixed designation B480; 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.
1. Scope a naturally occurring oxide film, usual procedures for the
preparation of metals for autocatalytic or electrolytic plating
1.1 This guide describes two processes used for plating on
cannot be used.
magnesium and magnesium alloys: direct electroless nickel
plating and zinc immersion. Some users report that the direct
4. Reagents
electroless nickel procedure does not produce quite as high a
level of adhesion as zinc immersion.
4.1 PurityofReagents—Allacidsandchemicalsusedinthis
guide are of technical grade.Acid and base solutions are based
1.2 The values stated in SI units are to be regarded as
on the following assay materials:
standard. No other units of measurement are included in this
Ammonium hydroxide (NH OH) 30 mass %, density 0.895 g/L
standard. 4
Nitric acid (HNO ) 67 mass %, density 1.16 g/L
1.3 This standard does not purport to address all of the
Sulfuric acid (H SO ) 93 mass %, density 1.40 g/L
2 4
Hydrofluoric acid (HF) 70 mass %, density 1.258 g/L
safety concerns, if any, associated with its use. It is the
Phosphoric acid (H PO ) 85 mass %, density 1.689 g/L
3 4
responsibility of the user of this standard to establish appro-
4.2 Purity of Water—All water used for solutions, whether
priate safety, health, and environmental practices and deter-
new or recycled, should be monitored for cations, anions, and
mine the applicability of regulatory limitations prior to use.
organic matter that are known to interfere with the plating
For specific hazard statements, see 5.1.1 and 5.2.9.2.
process.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Processes
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.1 Procedures:
mendations issued by the World Trade Organization Technical
5.1.1 Wheel polish and buff parts for smooth, highly pol-
Barriers to Trade (TBT) Committee.
ished surfaces.Tumble and burnish small parts.Acid pickle the
parts after use of wire brushing or steel wool. (Warning—
2. Referenced Documents
Because of the high flammability of powdered magnesium,
special precautions against fire are important. Polishing and
2.1 ASTM Standards:
B322 Guide for Cleaning Metals Prior to Electroplating buffing lathes should be kept scrupulously clean. Dust from
grinding in and around lathes should be swept up and placed in
3. Significance and Use closed containers for proper disposal. Exhaust systems should
be cleaned frequently and the residues handled similarly. If
3.1 Metals are electroplated on magnesium for various
abrasives are used in tumble finishing, similar precautionary
purposes: solderability, RF grounding, hermetic sealing, wear
techniques should be used for the solids from the abrasive
resistance, corrosion resistance, appearance, and electrical
slurry.)
conductivity, for example. Because magnesium is covered with
5.1.2 Chemical—Remove oil and grease in an alkaline soak
cleaner. Remove other soils and coatings in suitable acid
pickling solutions.
This guide is under the jurisdiction of ASTM Committee B08 on Metallic and
Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on Pre
NOTE 1—General information on the cleaning of metals is given in
Treatment.
Practice B322.
Current edition approved May 1, 2022. Published June 2022. Originally
5.2 General Electroplating Procedure:
approvedin1968.Lastpreviouseditionapprovedin2017asB480 – 88(2017).DOI:
10.1520/B0480-88R22.
5.2.1 Remove oil, grease, and other soils left from preplat-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ing procedures by soak cleaning in an alkaline cleaner suitable
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
for magnesium.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 5.2.2 Rinse in cold water.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B480 − 88 (2022)
NOTE 2—As generally used in rinsing terminology, cold water refers to
fiberglass equipment of any kind. Careful control is essential
water from an unheated water supply as opposed to heated water used for
for best results. Maintain the pH between 10.2 and 10.4
drying or other purposes. In some areas, particularly in water, ambient
electrometric(glasselectrode)measuredat25 °C.(Warning—
water temperatures may be too low for effective rinsing. In those
The glass electrode must be used with caution. Do not allow
instances, the rinse water may need to be heated.Aminimum temperature
the electrode to remain in contact with the zincate solution for
of 16 °C is recommended for effective rinsing.
prolonged periods. Inspect and test the electrode regularly to
5.2.3 Electroclean parts in an alkaline electrocleaner suit-
ensure that no change has occurred from contact with fluoride
ableformagnesium.Makethemagnesiumcathodicat7.5to13
ion. Colorimetric (paper) methods may be used. However, the
A/dm and 85 °C.
colorimetric readings may vary 60.5 pH units.)
5.2.4 Rinse in cold water.
5.2.10 Rinse thoroughly in cold water.
5.2.5 Pickle in one of the following solutions:
5.2.5.1 Ferric Nitrate Pickle: NOTE 6—For alloys M1660, M13120, M13312, or M13310, a double
zinc immersion is required. After step 5.2.10, steps 5.2.7 – 5.2.10 are
Chromic acid (CrO ) 180 g/L
repeated followed by step 5.2.11. It is advisable to use separate solutions
Ferric nitrate (Fe(NO )·9H O) 40 g/L
3 2
for steps 5.2.7 and 5.2.9 when the double zinc immersion technique is
Potassium fluoride (KF) 3.5 g/L
practiced.
Temperature 16 to 38 °C
Time 15sto3min
5.2.11 Copper strike in either of the following:
NOTE 3—This pickle removes metal from a surface at the rate of 3
Bath 1:
µm/min at 38 °C. Where no dimensional change can be tolerated, use of
the chromic acid pickle in 5.2.5.2 is recommended.
Copper cyanide (CuCN) 38 to 42 g/L
3 Potassium cyanide (KCN) 64.5 to 71.5 g/L
5.2.5.2 Chromic Acid Pickle:
Potassium fluoride (KF) 28.5 to 31.5 g/L
Chromic acid (CrO ) 180 g/L Free potassium cyanide 7 to 8 g/L
Temperature 16 to 93 °C pH 9.6 to 10.4
Time 2to10min Temperature 54 to 60 °C
NOTE 4—The use of chromic acid pickles may leave chromate films on
Bath 2:
the surface that will reduce the adhesion of the subsequently deposited
coating. Copper cyanide (CuCN) 38 to 42 g/L
Sodium cyanide (NaCN) 50 to 55 g/L
5.2.6 Rinse in cold water.
Rochelle salt (KNaC H O ·4H O) 40 to 48 g/L
4 4 6 2
5.2.7 Activate in the following solution: Free sodium cyanide 7 to 8 g/L
pH 9.6 to 10.4
Phosphoric acid, (H PO ) 20 % by vol
3 4
Temperature 54 to 60 °C
Ammonium bifluoride (NH HF ) 105 g/L
4 2
Temperature 16 to 38 °C 5.2.11.1 Platethepartsabout6min.Cathoderodagitationis
Time 15sto2min
suggested. With either bath make electrical contact quickly
5.2.8 Rinse in cold water. withinitialcurrent5to10A/dm ,thenlowercurrentto1to2.5
5.2.9 Zinc coat in the following solution: A/dm .
5.2.12 Rinse thoroughly in cold water.
Zinc sulfate (ZnSO ·H O) 30 g/L
4 2
Tetrasodium pyrophosphate (Na P O ) 120 g/L
5.2.13 Dip in diluted acid (1 % by vol sulfuric acid + 99 %
4 2 7
Sodium fluori
...