ASTM B877-96(2008)
(Test Method)Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by the Phosphomolybdic Acid (PMA) Method
Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by the Phosphomolybdic Acid (PMA) Method
SIGNIFICANCE AND USE
The primary purpose of the PMA test is to determine the presence of mechanical damage, wear through, and other gross defects in the coating. Most metallic coatings are intended to be protective, and the presence of gross defects indicates a serious reduction of such protection.
The protection afforded by well applied coatings may be diminished by improper handling following plating or as a result of wear or mechanical damage during testing or while in service. The PMA test can serve to indicate the existence of such damage.
This test is used to detect underplate and substrate metal exposed through normal wear during relative motions (mating of electrical contacts) or through mechanical damage. As such, it is a sensitive pass/fail test and, if properly performed, will rapidly detect wear through to base metals or scratches that enter the base metal layers.
This test is relatively insensitive to small pores. It is not designed to be a general porosity test and shall not be used as such. The detection of pores will depend upon their sizes and the length of time that the reagent remains a liquid.
This test cannot distinguish degrees of wear through or whether the wear through is to nickel or copper. Once base metal is exposed, the colored molybdenum complex is formed. While relatively small area defects (compared to the area of the droplet) may be seen at the bottom of the drop as tiny colored regions immediately after applying the PMA, any larger areas of exposed base metal will cause the entire droplet to turn dark instantly.
The PMA test also detects mechanical damage that exposes underplate and substrate metal. Such damage may occur in any postplating operation or even at the end of the plating operation. It can often occur in assembly operations where plated parts are assembled into larger units by mechanical equipment.
The PMA test identifies the locations of exposed base metal. The extent and location of these exposed areas may or may not be detrime...
SCOPE
1.1 This test standard covers equipment and methods for using phosphomolybdic acid (PMA) to detect gross defects and mechanical damage including wear through in metallic coatings of gold, silver, or palladium. These metals comprise the topmost metallic layers over substrates of nickel, copper, or copper alloys.
1.2 Recent reviews of porosity testing, which include those for gross defects, and testing methods can be found in the literature. , An ASTM guide to the selection of porosity and gross defect tests for electrodeposits and related metallic coatings is available as Guide B 765. Other related porosity and gross defects test standards are Test Methods B 735, B 741, B 798, B 799, B 809, and B 866, Specifications B 488, B 679,and B 689.
1.3 The values stated in SI units are the preferred units. Those in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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
Designation: B877 − 96(Reapproved 2008)
Standard Test Method for
Gross Defects and Mechanical Damage in Metallic Coatings
1
by the Phosphomolybdic Acid (PMA) Method
This standard is issued under the fixed designation B877; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope B542Terminology Relating to Electrical Contacts andTheir
Use
1.1 This test standard covers equipment and methods for
B679Specification for Electrodeposited Coatings of Palla-
usingphosphomolybdicacid(PMA)todetectgrossdefectsand
dium for Engineering Use
mechanical damage including wear through in metallic coat-
B689Specification for Electroplated Engineering Nickel
ings of gold, silver, or palladium. These metals comprise the
Coatings
topmost metallic layers over substrates of nickel, copper, or
B735Test Method for Porosity in Gold Coatings on Metal
copper alloys.
Substrates by Nitric Acid Vapor
1.2 Recent reviews of porosity testing, which include those
B741Test Method for Porosity In Gold Coatings On Metal
5
for gross defects, and testing methods can be found in the
Substrates By Paper Electrography (Withdrawn 2005)
2,3
literature. An ASTM guide to the selection of porosity and
B765GuideforSelectionofPorosityandGrossDefectTests
gross defect tests for electrodeposits and related metallic
for Electrodeposits and Related Metallic Coatings
coatingsisavailableasGuideB765.Otherrelatedporosityand
B798Test Method for Porosity in Gold or Palladium Coat-
gross defects test standards are Test Methods B735, B741,
ings on Metal Substrates by Gel-Bulk Electrography
B798, B799, B809, and B866, Specifications B488, B679,and
B799Test Method for Porosity in Gold and Palladium
B689.
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
1.3 The values stated in SI units are the preferred units. B809Test Method for Porosity in Metallic Coatings by
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
Those in parentheses are for information only.
B866Test Method for Gross Defects and Mechanical Dam-
1.4 This standard does not purport to address all of the
age in Metallic Coatings by Polysulfide Immersion
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety and health practices and determine the applica-
3.1 Definitions—Many terms in this test method are defined
bility of regulatory limitations prior to use.
in Terminology B374 or B542
2. Referenced Documents
3.2 Definitions of Terms Specific to This Standard:
4
2.1 ASTM Standards: 3.2.1 base metal, n—any metal other than gold, silver,
B374Terminology Relating to Electroplating platinum, palladium, iridium, or rhodium. Typical base metals
B488Specification for Electrodeposited Coatings of Gold used as underplates or substrates are copper, nickel, tin, lead,
for Engineering Uses and their alloys.
3.2.2 defect indications, n—colored droplets resulting from
the reaction between the PMA reagent and the underlying
1
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
metal.
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.10 on
3.2.3 gross defects, n—those breaks in the coating that
Test Methods.
Current edition approved Aug. 1, 2008. Published September 2008. Originally
expose relatively large areas of underlying metal to the
approved in 1996. Last previous edition approved in 2003 as B877–96 (2003).
environment. Gross defects include those produced by me-
DOI: 10.1520/B0877-96R08.
chanicaldamageandwear,aswellasas-platedlargeporeswith
2
Clarke,M.,“PorosityandPorosityTests,” Properties of Electrodeposits,ed.by
diameters an order of magnitude greater than intrinsic porosity
Sand, Leidheiser, and Ogburn, The Electrochemical Society, 1975, p. 122.
3
Krumbein, S. J., “PorosityTesting of Contact Platings,”Trans. Connectors and
and networks of microcracks.
Interconnection Technology Symposium, Philadelphia, PA, October 1987, p. 47.
4
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
5
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B877 − 96 (2008)
NOTE 1—Large pores and microcrack networks indicate serious devia-
5. Significance and Use
tions from acceptable coating practice (dirty substrates and con
...
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