ASTM B866-95(2008)
(Test Method)Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by Polysulfide Immersion
Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by Polysulfide Immersion
SIGNIFICANCE AND USE
The purpose of the alkaline polysulfide immersion 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 alkaline polysulfide test serves to indicate if the damage has extended down to the copper or copper alloy basis metal since it will not detect exposed nickel underplate.
The alkaline polysulfide test has been specified in several ASTM specifications for tin-plated coatings, namely Specifications B 246 and B 545. This test could also be used to detect gross defects and mechanical damage in other metallic coatings, such as tin-nickel alloy (Specification B 605), nickel (Specification B 689), gold (Specification B 488), palladium (Specification B 679), and autocatalytic nickel-phosphorous coatings (Specification B 733).
This test detects mechanical damage that exposes copper underplate and copper basis metal. Such damage may occur in any post-plating operation or even towards the end of the plating operation. It is most often seen to occur in product assembly operations.
If properly performed, this test will also detect wear-through, provided the wear-through reaches a copper or copper-alloy layer.
Many types of gross defects are too small to be seen, except at magnifications so high (as in SEM) that a realistic assessment of the measurement area cannot be easily made. Other defects, such as many types of wear-through, provide insufficient contrast with the coating surface. Gross defects tests (as with porosity tests) are, therefore, used to magnify the defect sites by producing visible reaction products in and around the defects.
The polysulfide solution will react with copper ...
SCOPE
1.1 This test method covers equipment and methods for detecting gross defects and mechanical damage (including wear-through) in metallic coatings where the breaks in the coating penetrate down to a copper or copper alloy substrate.
1.2 This test method is suitable for coatings consisting of single or combined layers of any coating that does not significantly tarnish in an alkaline polysulfide solution. Examples are gold, nickel, tin, tin-lead, and palladium, or their alloys.
1.3 Recent reviews of porosity testing (which include those for gross defects) and testing methods can be found in 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 test standards are Test Methods B 735, B 741, B 798, B 799, and B 809.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:B866 −95(Reapproved 2008)
Standard Test Method for
Gross Defects and Mechanical Damage in Metallic Coatings
by Polysulfide Immersion
This standard is issued under the fixed designation B866; 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 B246Specification for Tinned Hard-Drawn and Medium-
Hard-Drawn Copper Wire for Electrical Purposes
1.1 This test method covers equipment and methods for
B374Terminology Relating to Electroplating
detecting gross defects and mechanical damage (including
B488Specification for Electrodeposited Coatings of Gold
wear-through) in metallic coatings where the breaks in the
for Engineering Uses
coating penetrate down to a copper or copper alloy substrate.
B542Terminology Relating to Electrical Contacts andTheir
1.2 This test method is suitable for coatings consisting of
Use
single or combined layers of any coating that does not
B545Specification for Electrodeposited Coatings of Tin
significantly tarnish in an alkaline polysulfide solution. Ex-
B605Specification for Electrodeposited Coatings of Tin-
amples are gold, nickel, tin, tin-lead, and palladium, or their
Nickel Alloy
alloys.
B679Specification for Electrodeposited Coatings of Palla-
dium for Engineering Use
1.3 Recent reviews of porosity testing (which include those
for gross defects) and testing methods can be found in B689Specification for Electroplated Engineering Nickel
2,3
Coatings
literature. An ASTM guide to the selection of porosity and
gross defect tests for electrodeposits and related metallic B733Specification for Autocatalytic (Electroless) Nickel-
Phosphorus Coatings on Metal
coatingsisavailableasGuideB765.Otherrelatedporositytest
standards are Test Methods B735, B741, B798, B799, and B735Test Method for Porosity in Gold Coatings on Metal
Substrates by Nitric Acid Vapor
B809.
B741Test Method for Porosity In Gold Coatings On Metal
1.4 The values stated in SI units are to be regarded as the
Substrates By Paper Electrography (Withdrawn 2005)
standard. The values given in parentheses are for information
B765GuideforSelectionofPorosityandGrossDefectTests
only.
for Electrodeposits and Related Metallic Coatings
1.5 This standard does not purport to address all of the
B798Test Method for Porosity in Gold or Palladium Coat-
safety concerns, if any, associated with its use. It is the
ings on Metal Substrates by Gel-Bulk Electrography
responsibility of the user of this standard to establish appro-
B799Test Method for Porosity in Gold and Palladium
priate safety and health practices and determine the applica-
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
bility of regulatory limitations prior to use.
B809Test Method for Porosity in Metallic Coatings by
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Definitions: Many terms used in this test method are
defined in Terminologies B374 or B542.
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
3.2 Definitions of Terms Specific to This Standard:
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
Test Methods.
3.2.1 defect indications—black or dark colored products
Current edition approved Aug. 1, 2008. Published September 2008. Originally
resulting from the reaction between the alkaline polysulfide
approved in 1995. Last previous edition approved in 2003 as B866–03. DOI:
reagent and exposed copper or copper alloy underlying metal.
10.1520/B0866-95R08.
Clarke, M., “Porosity and Porosity Tests,” in Properties of Electrodeposits,
3.2.2 gross defects—breaks in the coating that expose rela-
edited by Sard, Leidheiser, and Ogburn,The Electrochemical Society, 1975, p. 122.
tively large areas of underlying metal to the environment
Krumbein, S. J., “PorosityTesting of Contact Platings,”Trans. Connectors and
(comparewith intrinsic porosity(3.2.3)).Grossdefectsinclude
Interconnection Technology Symposium, Philadelphia, PA, October 1987, p. 47.
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 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
B866−95 (2008)
thoseproducedbymechanicaldamageandwear,inadditionto 5.3 The alkaline polysulfide test has been specified in
as-plated large pores (with diameters an order of magnitude several ASTM specifications for tin-plated coatings, namely
greater than intrinsic porosity) and networks of microcracks. Specifications B246 and B545. This test could also be used to
detect gross defects and mechanical damage in other metallic
NOTE 1—Such large pores and microcrack networks indicate serious
coatings, such as tin-nickel alloy (Specification B605), nickel
deviations from acceptable coating practice (as, for example, dirty
(Specification B689), gold (Specification B488), palladium
basis-metal substrates and contaminated or out-of-balance plating baths).
(Specification B679), and autocatalytic nickel-phosphorous
3.2.3 intrinsic porosity—the “normal” porosity that is pres-
coatings (Specification B733).
ent, to some degree, in all commercial thin platings (such as in
precious-metal coatings for engineering purposes) and will
5.4 This test detects mechanical damage that exposes cop-
generally follow an inverse relationship with thickness.
perunderplateandcopperbasismetal.Suchdamagemayoccur
in any post-plating operation or even towards the end of the
NOTE 2—Intrinsic porosity is due primarily to small deviations from
plating operation. It is most often seen to occur in product
ideal plating and surface preparation conditions. Scanning electron mi-
croscope(SEM)studieshaveshownthatthediameterofsuchpores,atthe
assembly operations.
plating surface, is of the order of micrometres, so that only small areas of
5.5 If properly performed, this test will also detect wear-
underlying metal are exposed to the environment.
through, provided the wear-through reaches a copper or
3.2.4 measurement area—the portion or portions of the
copper-alloy layer.
surfaceexaminedforthepresenceofgrossdefectsormechani-
caldamage(andwear-through).Themeasurementareashallbe
5.6 Many types of gross defects are too small to be seen,
indicated on the drawings of the parts, or by the provision of
except at magnifications so high (as in SEM) that a realistic
suitably marked samples.
assessment of the measurement area cannot be easily made.
3.2.5 metallic coatings—platings, claddings, or other metal- Other defects, such as many types of wear-through, provide
lic coatings applied to the basis-metal substrate. The coating insufficient contrast with the coating surface. Gross defects
can comprise a single metallic layer or a combination of tests(aswithporositytests)are,therefore,usedtomagnifythe
metallic layers. defect sites by producing visible reaction products in and
around the defects.
3.2.6 porosity (general)—in a coating, the presence of any
hole,crack,orotherdefectthatexposestheunderlyingmetalto
5.7 The polysulfide solution will react with copper and
the environment.
copperalloystoproduceadarkbrownorblackstain(thedefect
3.2.7 underplate—ametalliccoatinglayerbetweenthebasis indications) at the site of the defect. Silver also turns black
underthesameconditions.Thetestsolutionwillnotreactwith
metal and the topmost metallic coating. The thickness of an
underplatingisusuallygreaterthan1µm,incontrasttoastrike nickel and is only useful when the presence or absence of
copper exposure is a specific requirement.
or flash, which is usually thinner.
3.2.8 wear-through—the exposure of underplate or basis
5.8 The polysulfide immersion test is relatively insensitive
metal as a direct result of wear. Wear-through is an observable
to the presence of small pores. It shall not be used as a general
phenomenon.
porosity test. (Test Method B809 should be used instead.)
3.2.9 wear track—a mark that indicates the path along
5.9 Theextentandlocationofthegrossdefectsormechani-
whichphysicalcontacthadbeenmadeduringaslidingprocess
cal damage (revealed by this test) may or may not be
(such as the mating and unmating of an electrical contact).
detrimental to product performance or service life. Such
determinations shall be made by the user of the test through
4. Summary of Test Method
practical experience or judgment.
4.1 Thetestsamplesareimmersedinanalkalinepolysulfide
5.10 The present test can be used on samples of various
solution at 74°C (165°F) for 60 s.After rinsing and drying, the
geometries, such as curved surfaces. It can also be used for
samples are examined for dark or discolored areas which
selectiveareacoatingifallowanceismadefortarnishcreepage
indicate exposure of copper or copper alloys to the solution
from bare copper alloy areas.
through breaks in the coating.
5.11 Thistestisdestructiveinthatitrevealsthepresenceof
5. Significance and Use
gross defects by contaminating the surface with reaction-
5.1 Thepurposeofthealkalinepolysulfideimmersiontestis
productfilms.Anypartsexposedtothistestshallnotbeplaced
to determine the presence of mechanical damage, wear-
in service.
through, and other gross defects in the coating. Most metallic
5.12 However,thedefectindicationsonthesamplesurfaces
coatingsareintendedtobeprotectiveandthepresenceofgross
thatresultfromthistestarestable;samplesmayberetainedfor
defects indicates a serious reduction of such protection.
reference purposes.
5.2 Theprotectionaffordedbywellappliedcoatingsmaybe
diminished by improper handling following plating or as a 5.13 This test is neither recommended for predictions of
resultofwearormechanicaldamageduringtestingorwhilein product performance nor is it intended to simulate field failure
service. The alkaline polysulfide test serves to indicate if the mechanisms. For such product performance evaluations, an
damage has extended down to the copper or copper alloy basis environmental test that is known to simulate actual failure
metal since it will not detect exposed nickel underplate. mechanisms should be used.
B866−95 (2008)
6. Apparatus 9.1.1.8 Store solution in a tightly capped 25
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