ASTM B867-95(2008)
(Specification)Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use
Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use
ABSTRACT
This specification establishes the requirements for electrodeposited palladium-nickel (Pd-Ni) coatings for engineering applications. Composite coatings consisting of palladium-nickel and a thin gold over-plate for applications involving electrical contacts are also covered. The classification system for the coatings covered here shall be specified by the basis metal, the thickness of the underplating, the composition type and thickness class of the palladium-nickel coating, and the grade of the gold overplating. Coatings should be sampled, tested, and conform to specified requirements as to purity, appearance, thickness, composition, adhesion, ductility, and integrity (including gross defects, mechanical damage, porosity, and microcracks). Alloy composition shall be examined either by wet method, X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Auger or electron probe X-ray microanalysis (EPMA), or wavelength dispersive spectroscopy (WDS). Coating adhesion shall be analyzed either by bend, heat, or cutting test.
SCOPE
1.1 Composition—This specification covers requirements for electrodeposited palladium-nickel coatings containing between 70 and 95 mass % of palladium metal. Composite coatings consisting of palladium-nickel and a thin gold overplate for applications involving electrical contacts are also covered.
1.2 Properties—Palladium is the lightest and least noble of the platinum group metals. Palladium-nickel is a solid solution alloy of palladium and nickel. Electroplated palladium-nickel alloys have a density between 10 and 11.5, which is substantially less than electroplated gold (17.0 to 19.3) and comparable to electroplated pure palladium (10.5 to 11.8). This yields a greater volume or thickness of coating per unit mass and, consequently, some saving of metal weight. The hardness range of electrodeposited palladium-nickel compares favorably with electroplated noble metals and their alloys (1, 2).
Note 1—Electroplated deposits generally have a lower density than their wrought metal counterparts.
Approximate Hardness (HK25) Gold 50–250 Palladium 75–600 Platinum150–550 Palladium-Nickel300–650 Rhodium 750–1100 Ruthenium600–1300
1.3 The values stated in SI units are to be regarded as the standard. The values given 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.
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Designation:B867 −95(Reapproved 2008)
Standard Specification for
Electrodeposited Coatings of Palladium-Nickel for
Engineering Use
This standard is issued under the fixed designation B867; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 Composition—This specification covers requirements
for electrodeposited palladium-nickel coatings containing be- B183Practice for Preparation of Low-Carbon Steel for
Electroplating
tween 70 and 95 mass % of palladium metal. Composite
coatings consisting of palladium-nickel and a thin gold over- B242Guide for Preparation of High-Carbon Steel for Elec-
troplating
plate for applications involving electrical contacts are also
covered. B254Practice for Preparation of and Electroplating on
Stainless Steel
1.2 Properties—Palladium is the lightest and least noble of
B281Practice for Preparation of Copper and Copper-Base
the platinum group metals. Palladium-nickel is a solid solution
Alloys for Electroplating and Conversion Coatings
alloy of palladium and nickel. Electroplated palladium-nickel
B322Guide for Cleaning Metals Prior to Electroplating
alloys have a density between 10 and 11.5, which is substan-
B343Practice for Preparation of Nickel for Electroplating
tially less than electroplated gold (17.0 to 19.3) and compa-
with Nickel
rabletoelectroplatedpurepalladium(10.5to11.8).Thisyields
B374Terminology Relating to Electroplating
a greater volume or thickness of coating per unit mass and,
B481Practice for Preparation of Titanium and Titanium
consequently, some saving of metal weight. The hardness
Alloys for Electroplating
rangeofelectrodepositedpalladium-nickelcomparesfavorably
2 B482Practice for Preparation of Tungsten and Tungsten
with electroplated noble metals and their alloys (1, 2).
Alloys for Electroplating
NOTE 1—Electroplated deposits generally have a lower density than
B487Test Method for Measurement of Metal and Oxide
their wrought metal counterparts.
Coating Thickness by Microscopical Examination of
Approximate Hardness (HK )
Cross Section
Gold 50–250
B488Specification for Electrodeposited Coatings of Gold
Palladium 75–600
Platinum 150–550 for Engineering Uses
Palladium-Nickel 300–650
B489Practice for Bend Test for Ductility of Electrodepos-
Rhodium 750–1100
ited and Autocatalytically Deposited Metal Coatings on
Ruthenium 600–1300
Metals
1.3 The values stated in SI units are to be regarded as the
B507Practice for Design ofArticles to Be Electroplated on
standard. The values given in parentheses are for information
Racks
only.
B542Terminology Relating to Electrical Contacts andTheir
1.4 This standard does not purport to address all of the
Use
safety concerns, if any, associated with its use. It is the
B558Practice for Preparation of Nickel Alloys for Electro-
responsibility of the user of this standard to establish appro-
plating
priate safety and health practices and determine the applica-
B568Test Method for Measurement of Coating Thickness
bility of regulatory limitations prior to use.
by X-Ray Spectrometry
B571Practice for Qualitative Adhesion Testing of Metallic
Coatings
B602Test Method for Attribute Sampling of Metallic and
This specification is under the jurisdiction of ASTM Committee B08 on
Metallic and Inorganic Coatings and is under the direct responsibility of Subcom-
Inorganic Coatings
mittee B08.03 on Engineering Coatings.
Current edition approved Aug. 1, 2008. Published September 2008. Originally
approved in 1995. Last previous edition approved in 2003 as B867–95 (2003). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/B0867-95R08. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Standards volume information, refer to the standard’s Document Summary page on
this specification. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B867−95 (2008)
TABLE 1 Composition Type
B697Guide for Selection of Sampling Plans for Inspection
of Electrodeposited Metallic and Inorganic Coatings Type Nominal Composition (Mass %) Range (Mass% Pd)
B741Test Method for Porosity In Gold Coatings On Metal I 75 % Pd/25 % Ni 70–80 % Pd
II 80 % Pd/20 % Ni 75–85 % Pd
Substrates By Paper Electrography (Withdrawn 2005)
III 85 % Pd/15 % Ni 80–90 % Pd
B748Test Method for Measurement of Thickness of Metal-
IV 90 % Pd/10 % Ni 85–95 % Pd
lic Coatings by Measurement of Cross Section with a
Scanning Electron Microscope
A
B762Test Method of Variables Sampling of Metallic and TABLE 2 Thickness Class
Inorganic Coatings Thickness Class Minimum Thickness of Pd-Ni (µm)
B765GuideforSelectionofPorosityandGrossDefectTests 0.4 0.4
0.5 0.5
for Electrodeposits and Related Metallic Coatings
0.7 0.7
B798Test Method for Porosity in Gold or Palladium Coat-
1.0 1.0
ings on Metal Substrates by Gel-Bulk Electrography 1.3 1.3
1.5 1.5
B799Test Method for Porosity in Gold and Palladium
2.0 2.0
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
2.5 2.5
B809Test Method for Porosity in Metallic Coatings by 3.0 3.0
A
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
See Appendix X3 on Electrical Contact Performance Versus Thickness Class.
B827Practice for Conducting Mixed Flowing Gas (MFG)
Environmental Tests
A
TABLE 3 Gold Overplate
B845Guide for Mixed Flowing Gas (MFG) Tests for Elec-
MIL-G- Thickness
trical Contacts
Grade Type Hardness (Code)
45204 Range
B849Specification for Pre-Treatments of Iron or Steel for
0 No Overplate . . .
Reducing Risk of Hydrogen Embrittlement
1 1 (99.9 % Au min) III 90 HK max (A) 0.05–0.12 µm
B850GuideforPost-CoatingTreatmentsofSteelforReduc-
2 2 (99.7 % Au min) I 130–200 HK (C) 0.05–0.25 µm
ing the Risk of Hydrogen Embrittlement A
See Specification B488 and Appendix X1 and Appendix X2.
D1125Test Methods for Electrical Conductivity and Resis-
tivity of Water
D3951Practice for Commercial Packaging
5. Ordering Information
3. Terminology
5.1 In order to make the application of this specification
3.1 Definitions: Many terms used in this specification are
complete,thepurchasershallsupplythefollowinginformation
defined in Terminology B374 or B542.
tothesellerinthepurchaseorderorothergoverningdocument:
3.2 Definitions of Terms Specific to This Standard: 5.1.1 The name, designation, and date of issue of this
3.2.1 overplating, n—a coating applied onto the topmost specification;
palladium-nickel coating. The thickness of an overplating or 5.1.2 The coating system including basis metal, composi-
“flash” is usually less than 0.25 µm. tiontype,thicknessclassandgoldoverplategrade(see4.1and
Table 1, Table 2, and Table 3);
3.2.2 significant surfaces, n—those surfaces normally vis-
5.1.3 Presence, composition, and thickness of underplating
ible (directly or by reflection) or which are essential to the
(see 3.2.1). For nickel underplating see 6.5.1;
serviceability or function of the article; or which can be the
5.1.4 Significant surfaces shall be defined (see 3.2.3);
sourceofcorrosionproductsortarnishfilmsthatinterferewith
5.1.5 Requirements, if any, for porosity testing (see 9.6);
the function or desirable appearance of the article. The signifi-
5.1.6 (Steel parts only) Stress relief if required (see Speci-
cantsurfacesshallbeindicatedonthedrawingsoftheparts,or
fication B849);
by the provision of suitably marked samples.
5.1.7 (Steel parts only) Hydrogen embrittlement relief (see
3.2.3 underplating, n—a metallic coating layer or layers
B850 );
between the basis metal or substrate and the palladium-nickel
5.1.8 Sampling plan employed (see Section 8); and,
coating. The thickness of an underplating is usually greater
5.1.9 Requirement, if any, for surface coating cleanliness
than 1 µm, in contrast to a strike which is thinner.
(absence of residual salts). See Appendix X6.
4. Classification
6. Manufacture
4.1 Orders for articles to be plated in accordance with this
6.1 Any process that provides an electrodeposit capable of
specification shall specify the coating system, indicating the
meeting the specified requirements will be acceptable.
basis metal, the thicknesses of the underplatings, the type and
thickness class of the palladium-nickel coating, and the grade 6.2 Substrate:
ofthegoldoverplatingaccordingtoTable1,Table2,andTable 6.2.1 The surface condition of the basis metal should be
3. See Section 7. specified and should meet this specification prior to the plating
of the parts.
6.2.2 Defects in the surface of the basis metal, such as
The last approved version of this historical standard is referenced on
www.astm.org. scratches, porosity, pits, inclusions, roll and die marks, laps,
B867−95 (2008)
cracks, burrs, cold shuts, and roughness may adversely affect 6.5.4 Gold Overplating—Applyathingoldoverplatingafter
the appearance and performance of the deposit, despite the the palladium-nickel in any application in which palladium-
observance of the best plating practice. Any such defects on nickel plated electrical connectors are mated together in a
significant surfaces should be brought to the attention of the contact pair. This process is necessary to preserve the perfor-
supplier and the purchaser. mance of the contact surface. See Appendix X1 for other
reasons for using a gold overplate.
6.2.3 Clean the basis metal as necessary to ensure a satis-
factory surface for subsequent electroplating in accordance
NOTE 6—When using Type 1 gold, the thickness of the gold overplate
with Practices B183, B242, B254, B281, B322, B343, B481,
shall not exceed 0.12 µm (5 µin.) due to increased risk of degrading
B482, and B558. durability and increasing the coefficient of friction.
6.2.4 Proper preparatory procedures and thorough cleaning
6.5.5 Residual Salts—For rack and barrel plating
of the basis metal are essential for satisfactory adhesion and
applications, residual plating salts can be removed from the
performanceofthesecoatings.Thesurfacemustbechemically
articles by a clean, hot (50 to 100°C) water rinse.Aminimum
clean and continuously conductive, that is, without inclusions
rinse time of 2.5 min (racks) or 5 min (barrel) is suggested.
orothercontaminants.Thecoatingsmustbesmoothandasfree
Best practice calls for a minimum of three dragout rinses and
of scratches, gouges, nicks, and similar imperfections as
onerunningrinsewithdwelltimesof40sineachstationwhen
possible.
rack plating and 80 s when barrel plating. Modern high-
velocity impingement type rinses can reduce this time to a few
NOTE 2—A metal finisher can often remove defects through special
seconds. This is particularly useful in automatic reel-to-reel
treatments such as grinding, polishing, abrasive blasting, chemical
applications where dwell times are significantly reduced. See
treatments,andelectropolishing.However,thesemaynotbenormalinthe
treatmentstepsprecedingtheplating,andaspecialagreementisindicated.
Appendix X6.
6.3 Ifrequired(see5.1.6),steelpartswithahardnessgreater
7. Coating Requirements
than 1000 MPa (31 HRC) shall be given a suitable stress relief
7.1 Nature of Coating—The palladium-nickel deposit shall
heattreatmentpriortoplatinginaccordancewithSpecification
have a minimum purity of 70 mass % palladium.
B849.Suchstressreliefshallnotreducethehardnesstoavalue
below the specified minimum. Avoid acid pickling of high
7.2 Composition—The composition of the palladium-nickel
strength steels.
electrodepositshallbewithin 65mass%ofthespecifiedtype.
6.3.1 Applythecoatingafterallbasismetalpreparatoryheat
7.3 Appearance—Palladium-nickel coatings shall be
treatments and mechanical operations on significant surfaces
coherent, continuous, and have a uniform appearance to the
have been completed.
extent that the nature of the basis metal and good commercial
6.4 Racking: practices permit.
6.4.1 Positionpartstoallowfreecirculationofsolutionover
7.4 Thickness—Everywhere on the significant surface (see
all surfaces. The location of rack or wire marks in the coating
5.1), the thickness of the palladium-nickel coating shall be
should be agreed upon between the producer and supplier.
equal to or exceed the specified thickness. The maximum
thickness, however, shall not exceed the drawing tolerance.
6.5 Plating Process:
6.5.1 Nickel Underplating—Apply a nickel underplating
NOTE 7—The coating thickness requirement of this specification is a
minimumrequirement,thatis,thecoatingthicknessisrequiredtoequalor
before the palladium-nickel when the product is made from
exceed the specified thickness everywhere on the significant surfaces
copper or copper alloy. Nickel underplatings are also applied
while conforming to all maximum thickness tolerances given in the
for other reasons. See Appendix X5.
engineeringdrawing.Variationinthecoatingthicknessfrompointtopoint
onacoatedarticleisaninherentcharacteristicofelectroplatingprocesses.
NOTE 3—In certain instances where high frequency analog signals are
The coating thickness at any single point on the significant surface,
employed, such as wave guides, the magnetic properties of nickel may
therefore, will sometimes have to exceed the specified value in order to
attenuatethesignal.Palladium-nickelitselfisnon-ferromagneticwhenthe
ensurethatthethicknessequalsorexceedsthespecifiedvalueatallpoints.
nickel content is less than 14 mass %.
Hence,mostaveragecoatingthicknesseswillbegreaterthanthespecified
NOTE 4—In applications where forming or flaring operations are to be
value. How much greater is largely determined by the shape of the article
applied to the plated component, a ductile nickel electrodeposit should be
(see Practice B507) and the characteristics of the plating process. In
specified.
addition, the average coating thickness on products will vary from article
to article within a production lot. If all of the articles in a production lot
6.5.2 Strikes—Good practice suggests the use of a palla-
are to meet the thickness requirement, the average coating thickness for
dium strike to follow any underplate or substrate (other than
theproductionlotasawholewillbegreaterthantheaveragenecessaryto
silver or platinum) immediately prior to applying the
assure that a single article meets the requirement. See 8.1.
palladium-nickel.
7.5 Adhesion—The palladium-nickel coatings shall be ad-
6.5.3 Plating—Good practice calls for the work to be
herent to the substrate or underplate when tested by one of the
electrically connected when entering the palladium-nickel
procedures summarized in 9.5.
so
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