ASTM B679-98(2004)e1

Standard Specification for Electrodeposited Coatings of Palladium for Engineering Use

ABSTRACT
This specification establishes the requirements for electrodeposited palladium coatings for use in engineering applications. This specification also covers composite coatings of palladium with a thin gold overplate for applications involving electrical contacts. The plating system shall indicate the basis metal involved, thickness of the underplates, thickness of the palladium coating, and grade of the gold overplate. Coatings shall be sampled, tested, and conform accordingly to specified requirements as to purity, appearance, thickness, dutility, adhesion (to be examined either by bend, heat, or cutting test), and integrity (gross defects, mechanical damage, and porosity).
SCOPE
1.1 Purity -This specification covers requirements for electrodeposited palladium coatings containing at least 99.7 mass % of palladium metal.
1.2 Properties -Palladium is the lightest and least noble of the platinum group metals. It has a specific gravity of 12.0, which is substantially less than gold (19.3) and platinum (21.5). This yields a greater volume or thickness of coating and, consequently, some saving of metal weight accompanied by a small sacrifice in corrosion resistance and reflectivity. The hardness range of electrodeposited palladium compares favorably with the other electroplated noble metals and their alloys.  
1.3 The values stated in SI units are the preferred values. Values provided in parentheses are for information only.
1.4 The following hazards caveat pertains only to the test methods section of this specification: This standard does not purport to address all of the safety problems, 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

• Status: Historical
• Publication Date: 31-Mar-2004
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.04 - Precious Metal Coatings

Relations

• Replaces: ASTM B679-98 - Standard Specification for Electrodeposited Coatings of Palladium for Engineering Use
• Effective Date: 01-Apr-2004
• Replaced By: ASTM B679-98(2009) - Standard Specification for Electrodeposited Coatings of Palladium for Engineering Use
• Effective Date: 01-Sep-2009
• Referred By: ASTM B866-95(2018) - Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by Polysulfide Immersion
• Effective Date: 01-Apr-2004
• Referred By: ASTM B984-12(2020)e1 - Standard Specification for Electrodeposited Coatings of Palladium-Cobalt Alloy for Engineering Use
• Effective Date: 01-Apr-2004
• Referred By: ASTM B877-96(2018) - Standard Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by the Phosphomolybdic Acid (PMA) Method
• Effective Date: 01-Apr-2004

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
´1
Designation: B679 – 98 (Reapproved 2004)
Standard Specification for
Electrodeposited Coatings of Palladium for Engineering
Use
This standard is issued under the fixed designation B679; 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.
´ NOTE—Warning note updated and keywords added editorially in April 2004.
1. Scope 2.2 ASTM Standards:
B183 Practice for Preparation of Low-Carbon Steel for
1.1 This specification covers requirements for electrodepos-
Electroplating
ited palladium coatings containing at least 99.7 mass % of
B242 Guide for Preparation of High-Carbon Steel for Elec-
palladium metal. Composite coatings consisting of palladium
troplating
with a thin gold overplate for applications involving electrical
B254 Practice for Preparation of and Electroplating on
contacts are also covered.
Stainless Steel
1.2 Properties—Palladium is the lightest and least noble of
B281 Practice for Preparation of Copper and Copper-Base
the platinum group metals. It has a specific gravity of 12.0,
Alloys for Electroplating and Conversion Coatings
which is substantially less than gold (19.3) and platinum
B322 Guide for Cleaning Metals Prior to Electroplating
(21.5). This yields a greater volume or thickness of coating
B343 Practice for Preparation of Nickel for Electroplating
and, consequently, some saving of metal weight accompanied
with Nickel
by a small sacrifice in corrosion resistance and reflectivity.The
B374 Terminology Relating to Electroplating
following table compares the hardness range of electrodepos-
B481 Practice for Preparation of Titanium and Titanium
ited palladium with other electrodeposited noble metals and
Alloys for Electroplating
alloys (1,2).
B482 Practice for Preparation of Tungsten and Tungsten
Approximate Hardness (HK )
Alloys for Electroplating
Gold 50–250
Palladium 75–600
B487 Test Method for Measurement of Metal and Oxide
Platinum 150–550
CoatingThicknessbyMicroscopicalExaminationofCross
Palladium-Nickel 300–650
Section
Rhodium 750–1100
Ruthenium 600–1300
B488 Specification for Electrodeposited Coatings of Gold
for Engineering Uses
1.3 The values stated in SI units are the preferred values.
B489 Practice for Bend Test for Ductility of Electrodepos-
Values provided in parentheses are for information only.
ited and Autocatalytically Deposited Metal Coatings on
1.4 This standard does not purport to address all of the
Metals
safety concerns, if any, associated with its use. It is the
B499 Test Method for Measurement of Coating Thick-
responsibility of the user of this standard to establish appro-
nessesbytheMagneticMethod:NonmagneticCoatingson
priate safety and health practices and determine the applica-
Magnetic Basis Metals
bility of regulatory limitations prior to use.
B507 Practice for Design ofArticles to Be Electroplated on
2. Referenced Documents
Racks
B542 Terminology Relating to Electrical Contacts and
2.1 The following standards form a part of this specification
Their Use
to the extent referenced herein:
B558 Practice for Preparation of NickelAlloys for Electro-
plating
This specification is under the jurisdiction of ASTM Committee B08 on
B567 Test Method for Measurement of Coating Thickness
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
B08.08.02 on Precious Metal Coatings.
Current edition approved April 1, 2004. Published April 2004. Originally
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1980. Last previous edition approved in 1998 as B679 – 98. DOI:
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
10.1520/B0679-98R04E01.
Standards volume information, refer to the standard’s Document Summary page on
The boldface numbers in parentheses refer to the list of references at the end of
this specification. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B679 – 98 (2004)
A
TABLE 1 Thickness Class
by the Beta Backscatter Method
B568 Test Method for Measurement of Coating Thickness Thickness Class Minimum Thickness of Pd (µm)
by X-Ray Spectrometry
0.08 0.08
0.15 0.15
B571 Practice for Qualitative Adhesion Testing of Metallic
0.25 0.25
Coatings
0.50 0.50
B602 Test Method for Attribute Sampling of Metallic and
0.75 0.75
1.00 1.00
Inorganic Coatings
1.25 1.25
B689 Specification for Electroplated Engineering Nickel
1.5 1.5
Coatings
2.5 2.5
3.0 3.0
B697 Guide for Selection of Sampling Plans for Inspection
5.0 5.0
of Electrodeposited Metallic and Inorganic Coatings
A
See Appendix X4 for specific applications of the various thickness classes.
B741 Test Method for Porosity In Gold Coatings On Metal
Substrates By Paper Electrography
A
TABLE 2 Gold Overplate
B748 Test Method for Measurement of Thickness of Me-
Thickness
tallic Coatings by Measurement of Cross Section with a
Grade Type MIL-G-45204 Hardness (Code)
Range
Scanning Electron Microscope
0 No Overplate . . . . . . . . .
B762 Test Method of Variables Sampling of Metallic and
1 1 (99.9 % Au min) III 90 HK max (A) 0.05-0.12 µm
Inorganic Coatings
2 2 (99.7 % Au min) I 130-200 HK (C) 0.05-0.25 µm
B765 Guide for Selection of Porosity and Gross Defect
A
See Specification B488 and Appendix X1.
Tests for Electrodeposits and Related Metallic Coatings
B799 Test Method for Porosity in Gold and Palladium
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
5.1.4 Significant surfaces shall be defined (see 3.2.2).
B809 Test Method for Porosity in Metallic Coatings by
5.1.5 Requirements, if any, for porosity testing (see 9.5):
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
5.1.6 Requirement, if any, for bend ductility testing (see
D1125 Test Methods for Electrical Conductivity and Resis-
9.6):
tivity of Water
5.1.7 Sampling plan employed (see Section 8), and
D3951 Practice for Commercial Packaging
5.1.8 Requirement, if any, for surface coating cleanliness
(absence of residual salts). See Appendix X3.
3. Terminology
3.1 Definitions—Many terms used in this specification are
6. Manufacture
defined in Terminology B374 or B542B374B542.
6.1 Any process that provides an electrodeposit capable of
3.2 Definitions of Terms Specific to This Standard:
meeting the specified requirements will be acceptable.
3.2.1 underplating—a metallic coating layer between the
6.2 Substrate:
basis metal or substrate and the topmost metallic coating. The
6.2.1 The surface condition of the basis metal should be
thickness of an underplating is usually greater than 1 µm (40
specified and should meet this specification prior to the plating
µin.), in contrast to a strike or flash.
of the parts.
4. Classification 6.2.2 Defects in the surface of the basis metal, such as
scratches, porosity, pits, inclusions, roll and die marks, laps,
4.1 Orders for articles to be plated in accordance with this
cracks, burrs, cold shuts, and roughness may adversely affect
specification shall specify the plating system, indicating the
the appearance and performance of the deposit, despite the
basis metal, the thickness of the underplatings, the thickness of
observance of the best plating practice. Any such defects on
the palladium coating, and the grade of the gold overplating
significant surfaces should be brought to the attention of the
according to Tables 1 and 2.
supplier and the purchaser.
6.2.3 Clean the basis metal as necessary to ensure a satis-
5. Ordering Information
factory surface for subsequent electroplating in accordance
5.1 In order to make the application of this standard
with Practices B183, B254, B281, B322, B343, B481, B482,
complete, the purchaser needs to supply the following infor-
and B558, and Guide B242.
mation to the seller in the purchase order or other governing
6.2.4 Proper preparatory procedures and thorough cleaning
document:
of the basis metal are essential for satisfactory adhesion and
5.1.1 The name, designation, and date of issue of this
performance of these coatings.The surface must be chemically
standard.
clean and continuously conductive, that is, without inclusions
5.1.2 The coating system including basis metal, thickness
orothercontaminants.Thecoatingsmustbesmoothandasfree
class and gold overplate grade (see 4.1 and Tables 1 and 2).
of scratches, gouges, nicks, and similar imperfections as
5.1.3 Presence, type, and thickness of underplating (see
possible.
3.2.3).
NOTE 1—A metal finisher can often remove defects through special
treatments such as grinding, polishing, abrasive blasting, chemical treat-
ments, and electropolishing. However, these may not be normal in the
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org. treatmentstepsprecedingtheplating,andaspecialagreementisindicated.
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B679 – 98 (2004)
6.3 Apply the coating after all basis metal preparatory 7.3 Thickness—Everywhere on the significant surface (see
treatments and mechanical operations on significant surfaces 5.1.4), the thickness of the palladium coating shall be equal to
have been completed. or exceed the specified thickness. The maximum thickness,
6.4 Racking: however, shall not exceed the drawing tolerance.
6.4.1 Positionpartstoallowfreecirculationofsolutionover
NOTE 4—The coating thickness requirement of this specification is a
all surfaces. The location of rack or wire marks in the coating
minimumrequirement;thatis,thecoatingthicknessisrequiredtoequalor
should be agreed upon between the producer and supplier.
exceed the specified thickness everywhere on the significant surfaces
6.5 Plating Process: while conforming to all maximum thickness tolerances given in the
engineeringdrawing.Variationinthecoatingthicknessfrompointtopoint
6.5.1 Nickel Underplating—Apply a nickel underplating
on a coated article is an inherent characteristic of electroplating processes.
before the palladium when the product is made from copper or
Therefore, the coating thickness will have to exceed the specified value at
copper alloy. Nickel underplatings are also applied for other
some points on the significant surfaces to ensure that the thickness equals
reasons. See Appendix X2.
or exceeds the specified value at all points. Hence, in most cases, the
average coating thickness on an article will be greater than the specified
NOTE 2—In certain instances where high frequency analog signals are
value; how much greater is largely determined by the shape of the article
employed, such as wave guides, the magnetic properties of nickel may
(see Practice B507) and the characteristics of the plating process.
attenuate the signal. Palladium itself is non-ferromagnetic.
In addition, the average coating thickness on articles will vary from
6.5.2 Strikes—Standard practice calls for a gold or palla-
article to article within a production lot. Therefore, if all of the articles in
dium strike to follow any underplate or substrate (other than
aproductionlotaretomeetthethicknessrequirement,theaveragecoating
silver or platinum) immediately prior to applying the palla- thicknessfortheproductionlotasawholewillbegreaterthantheaverage
necessary to assure that a single article meets the requirement.
dium.
6.5.3 Plating—Good practice calls for the work to be
7.4 Adhesion—The palladium coatings shall be adherent to
electrically connected when entering the bath. A minimum of
the substrate, when tested by one of the procedures summa-
0.5 V is suggested. During electroplating it is extremely
rized in 9.4.
important to maintain the voltage, current density, or both
7.5 Integrity of the Coating:
beneath the value for hydrogen evolution. (See 7.2)
7.5.1 Gross Defects/Mechanical Damage—The coatings
6.5.4 Stress Cracking—Problems associated with the incor-
shall be free of visible mechanical damage and similar gross
poration of hydrogen in the palladium, which can lead to stress
defects when viewed at magnifications up to 103. For some
cracking of the coating, shall be controlled by choosing plating
applications this requirement may be relaxed to allow for a
baths and plating conditions that minimize the H/Pd deposition
small number of such defects (per unit area), especially if they
ratio (3). The presence of stress-induced microcracks that
are outside of or on the periphery of the significant surfaces.
penetrate to the underlying substrate or underplating can be
See 7.5.2 and 6.5.4.
detected with one of the porosity tests specified in 9.5.
7.5.2 Porosity—Almostallas-platedelectrodepositscontain
6.5.5 Gold Overplating—Apply a thin gold overplating
some porosity, and the amount of porosity to be expected for
after the palladium in any application in which palladium
any one type of coating will increase with decreasing the
plated electrical connectors are mated together in a contact
thickness of that particular coating type. The amount of
pair. This process is necessary to preserve the performance of
porosity in the coating that may be tolerable depends on the
the contact surface. See Appendix X1 for other reasons for
severity of the environment that the article is likely to
using a gold overplate.
encounter during service or storage. If the pores are few in
number, or away from the significant surfaces, their presence
NOTE 3—When using Type 1 gold, the thickness of the gold overplate
can often be tolerated. Acceptance or pass-fail criteria, if
shall not exceed 0.12 µm (5 µin.) due to increased risk of degrading
durability and increasing the coefficient of friction. required, shall be part of the product specification for the
particular article or coating requiring the porosity test. See 9.5.
6.5.6 Residual Salts—For rack and barrel plating applica-
tions,residualplatingsaltscanberemovedfromthearticlesby
NOTE 5—Extensive reviews of porosity and porosity testing can be
a clean, hot (50 to 100°C) water rinse. A minimum rinse time found in the literature (4, 5).
of 2.5 min (racks) or 5 min (barrel) is suggested. Best practice
8. Sampling
calls for a minimum of three dragout rinses and one running
8.1 Thesamplingplanusedfortheinspectionofaqualityof
rinse with dwell times of 40 s in each station when rack plating
the coated articles shall be as agreed upon between the
and 80 s when barrel plating. Modern high-velocity impinge-
purchaser and the supplier.
ment type rinses can reduce this time to a few seconds. This is
particularly useful in automatic reel-to-reel applications where
NOTE 6—Usually, when a collection of coated articles, the inspection
dwell times are significantly reduced. See Appendix X3. lot (see 8.2), is examined for compliance wit
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