1、Designation: B679 98 (Reapproved 2009)Standard Specification forElectrodeposited Coatings of Palladium for EngineeringUse1This standard is issued under the fixed designation B679; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers requirements for electrodepos-ited palladium coatings containing at least 99.7 mass
3、 % ofpalladium metal. Composite coatings consisting of palladiumwith a thin gold overplate for applications involving electricalcontacts are also covered.1.2 PropertiesPalladium is the lightest and least noble ofthe platinum group metals. It has a specific gravity of 12.0,which is substantially less
4、 than gold (19.3) and platinum(21.5). This yields a greater volume or thickness of coatingand, consequently, some saving of metal weight accompaniedby a small sacrifice in corrosion resistance and reflectivity. Thefollowing table compares the hardness range of electrodepos-ited palladium with other
5、electrodeposited noble metals andalloys (1,2).2Approximate Hardness (HK25)Gold 50250Palladium 75600Platinum 150550Palladium-Nickel 300650Rhodium 7501100Ruthenium 60013001.3 The values stated in SI units are the preferred values.Values provided in parentheses are for information only.1.4 This standar
6、d does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 The
7、following standards form a part of this specificationto the extent referenced herein:2.2 ASTM Standards:3B183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB254 Practice for Preparation of and Electroplating onStainle
8、ss SteelB281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB322 Guide for Cleaning Metals Prior to ElectroplatingB343 Practice for Preparation of Nickel for Electroplatingwith NickelB374 Terminology Relating to ElectroplatingB481 Practice for Prep
9、aration of Titanium and TitaniumAlloys for ElectroplatingB482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB488 Specification for Electrodeposited Coatings of
10、 Goldfor Engineering UsesB489 Practice for Bend Test for Ductility of Electrodepos-ited and Autocatalytically Deposited Metal Coatings onMetalsB499 Test Method for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB507 Practice for Design of Arti
11、cles to Be Electroplated onRacksB542 Terminology Relating to Electrical Contacts andTheir UseB558 Practice for Preparation of Nickel Alloys for Electro-platingB567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB568 Test Method for Measurement of Coating Thicknessby X-
12、Ray Spectrometry1This specification is under the jurisdiction of ASTM Committee B08 on and isthe direct responsibility of Subcommittee B08.08.02 on Precious Metal Coatings.Current edition approved Sept. 1, 2009. Published November 2009. Originallyapproved in 1980. Last previous edition approved in 2
13、004 as B679 98(2004)1.DOI: 10.1520/B0679-98R09.2The boldface numbers in parentheses refer to the list of references at the end ofthis specification.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
14、ds volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.B571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute S
15、ampling of Metallic andInorganic CoatingsB689 Specification for Electroplated Engineering NickelCoatingsB697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB741 Test Method for Porosity In Gold Coatings On MetalSubstrates By Paper Electrography
16、4B748 Test Method for Measurement of Thickness of Me-tallic Coatings by Measurement of Cross Section with aScanning Electron MicroscopeB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB765 Guide for Selection of Porosity and Gross DefectTests for Electrodeposits and Related Me
17、tallic CoatingsB799 Test Method for Porosity in Gold and PalladiumCoatings by Sulfurous Acid/Sulfur-Dioxide VaporB809 Test Method for Porosity in Metallic Coatings byHumid Sulfur Vapor (“Flowers-of-Sulfur”)D1125 Test Methods for Electrical Conductivity and Resis-tivity of WaterD3951 Practice for Com
18、mercial Packaging3. Terminology3.1 DefinitionsMany terms used in this specification aredefined in Terminology B374 or B542.3.2 Definitions of Terms Specific to This Standard:3.2.1 underplatinga metallic coating layer between thebasis metal or substrate and the topmost metallic coating. Thethickness
19、of an underplating is usually greater than 1 m (40in.), in contrast to a strike or flash.4. Classification4.1 Orders for articles to be plated in accordance with thisspecification shall specify the plating system, indicating thebasis metal, the thickness of the underplatings, the thickness ofthe pal
20、ladium coating, and the grade of the gold overplatingaccording to Tables 1 and 2.5. Ordering Information5.1 In order to make the application of this standardcomplete, the purchaser needs to supply the following infor-mation to the seller in the purchase order or other governingdocument:5.1.1 The nam
21、e, designation, and date of issue of thisstandard.5.1.2 The coating system including basis metal, thicknessclass and gold overplate grade (see 4.1 and Tables 1 and 2).5.1.3 Presence, type, and thickness of underplating (see3.2.3).5.1.4 Significant surfaces shall be defined (see 3.2.2).5.1.5 Requirem
22、ents, if any, for porosity testing (see 9.5):5.1.6 Requirement, if any, for bend ductility testing (see9.6):5.1.7 Sampling plan employed (see Section 8), and5.1.8 Requirement, if any, for surface coating cleanliness(absence of residual salts). See Appendix X3.6. Manufacture6.1 Any process that provi
23、des an electrodeposit capable ofmeeting the specified requirements will be acceptable.6.2 Substrate:6.2.1 The surface condition of the basis metal should bespecified and should meet this specification prior to the platingof the parts.6.2.2 Defects in the surface of the basis metal, such asscratches,
24、 porosity, pits, inclusions, roll and die marks, laps,cracks, burrs, cold shuts, and roughness may adversely affectthe appearance and performance of the deposit, despite theobservance of the best plating practice. Any such defects onsignificant surfaces should be brought to the attention of thesuppl
25、ier and the purchaser.6.2.3 Clean the basis metal as necessary to ensure a satis-factory surface for subsequent electroplating in accordancewith Practices B183, B254, B281, B322, B343, B481, B482,and B558, and Guide B242.6.2.4 Proper preparatory procedures and thorough cleaningof the basis metal are
26、 essential for satisfactory adhesion andperformance of these coatings. The surface must be chemicallyclean and continuously conductive, that is, without inclusionsor other contaminants. The coatings must be smooth and as freeof scratches, gouges, nicks, and similar imperfections aspossible.NOTE 1A m
27、etal finisher can often remove defects through specialtreatments such as grinding, polishing, abrasive blasting, chemical treat-ments, and electropolishing. However, these may not be normal in thetreatment steps preceding the plating, and a special agreement is indicated.6.3 Apply the coating after
28、all basis metal preparatorytreatments and mechanical operations on significant surfaceshave been completed.4Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.TABLE 1 Thickness ClassAThickness Class Minimum Thickness of Pd (m)0.08 0.080.15 0.150.25 0.250.50
29、 0.500.75 0.751.00 1.001.25 1.251.5 1.52.5 2.53.0 3.05.0 5.0ASee Appendix X4 for specific applications of the various thickness classes.TABLE 2 Gold OverplateAGrade Type MIL-G-45204 Hardness (Code)ThicknessRange0 No Overplate . . . . . . . . .1 1 (99.9 % Au min) III 90 HK25max (A) 0.05-0.12 m2 2 (99
30、.7 % Au min) I 130-200 HK25(C) 0.05-0.25 mASee Specification B488 and Appendix X1.B679 98 (2009)26.4 Racking:6.4.1 Position parts to allow free circulation of solution overall surfaces. The location of rack or wire marks in the coatingshould be agreed upon between the producer and supplier.6.5 Plati
31、ng Process:6.5.1 Nickel UnderplatingApply a nickel underplatingbefore the palladium when the product is made from copper orcopper alloy. Nickel underplatings are also applied for otherreasons. See Appendix X2.NOTE 2In certain instances where high frequency analog signals areemployed, such as wave gu
32、ides, the magnetic properties of nickel mayattenuate the signal. Palladium itself is non-ferromagnetic.6.5.2 StrikesStandard practice calls for a gold or palla-dium strike to follow any underplate or substrate (other thansilver or platinum) immediately prior to applying the palla-dium.6.5.3 PlatingG
33、ood practice calls for the work to beelectrically connected when entering the bath. A minimum of0.5 V is suggested. During electroplating it is extremelyimportant to maintain the voltage, current density, or bothbeneath the value for hydrogen evolution. (See 7.2)6.5.4 Stress CrackingProblems associa
34、ted with the incor-poration of hydrogen in the palladium, which can lead to stresscracking of the coating, shall be controlled by choosing platingbaths and plating conditions that minimize the H/Pd depositionratio (3). The presence of stress-induced microcracks thatpenetrate to the underlying substr
35、ate or underplating can bedetected with one of the porosity tests specified in 9.5.6.5.5 Gold OverplatingApply a thin gold overplatingafter the palladium in any application in which palladiumplated electrical connectors are mated together in a contactpair. This process is necessary to preserve the p
36、erformance ofthe contact surface. See Appendix X1 for other reasons forusing a gold overplate.NOTE 3When using Type 1 gold, the thickness of the gold overplateshall not exceed 0.12 m (5 in.) due to increased risk of degradingdurability and increasing the coefficient of friction.6.5.6 Residual SaltsF
37、or rack and barrel plating applica-tions, residual plating salts can be removed from the articles bya clean, hot (50 to 100C) water rinse. A minimum rinse timeof 2.5 min (racks) or 5 min (barrel) is suggested. Best practicecalls for a minimum of three dragout rinses and one runningrinse with dwell t
38、imes of 40 s in each station when rack platingand 80 s when barrel plating. Modern high-velocity impinge-ment type rinses can reduce this time to a few seconds. This isparticularly useful in automatic reel-to-reel applications wheredwell times are significantly reduced. See Appendix X3.7. Coating Re
39、quirements7.1 Nature of CoatingThe palladium deposit shall haveminimum purity of 99.7 mass %.7.2 AppearancePalladium coatings shall be coherent,continuous, and have a uniform appearance to the extent thatthe nature of the basis metal and good commercial practicespermit.7.3 ThicknessEverywhere on the
40、 significant surface (see5.1.4), the thickness of the palladium coating shall be equal toor exceed the specified thickness. The maximum thickness,however, shall not exceed the drawing tolerance.NOTE 4The coating thickness requirement of this specification is aminimum requirement; that is, the coatin
41、g thickness is required to equal orexceed the specified thickness everywhere on the significant surfaceswhile conforming to all maximum thickness tolerances given in theengineering drawing. Variation in the coating thickness from point to pointon a coated article is an inherent characteristic of ele
42、ctroplating processes.Therefore, the coating thickness will have to exceed the specified value atsome points on the significant surfaces to ensure that the thickness equalsor exceeds the specified value at all points. Hence, in most cases, theaverage coating thickness on an article will be greater t
43、han the specifiedvalue; how much greater is largely determined by the shape of the article(see Practice B507) and the characteristics of the plating process.In addition, the average coating thickness on articles will vary fromarticle to article within a production lot. Therefore, if all of the artic
44、les ina production lot are to meet the thickness requirement, the average coatingthickness for the production lot as a whole will be greater than the averagenecessary to assure that a single article meets the requirement.7.4 AdhesionThe palladium coatings shall be adherent tothe substrate, when test
45、ed by one of the procedures summa-rized in 9.4.7.5 Integrity of the Coating:7.5.1 Gross Defects/Mechanical DamageThe coatingsshall be free of visible mechanical damage and similar grossdefects when viewed at magnifications up to 103. For someapplications this requirement may be relaxed to allow for
46、asmall number of such defects (per unit area), especially if theyare outside of or on the periphery of the significant surfaces.See 7.5.2 and 6.5.4.7.5.2 PorosityAlmost all as-plated electrodeposits containsome porosity, and the amount of porosity to be expected forany one type of coating will incre
47、ase with decreasing thethickness of that particular coating type. The amount ofporosity in the coating that may be tolerable depends on theseverity of the environment that the article is likely toencounter during service or storage. If the pores are few innumber, or away from the significant surface
48、s, their presencecan often be tolerated. Acceptance or pass-fail criteria, ifrequired, shall be part of the product specification for theparticular article or coating requiring the porosity test. See 9.5.NOTE 5Extensive reviews of porosity and porosity testing can befound in the literature (4, 5).8.
49、 Sampling8.1 The sampling plan used for the inspection of a quality ofthe coated articles shall be as agreed upon between thepurchaser and the supplier.NOTE 6Usually, when a collection of coated articles, the inspectionlot (see 8.2), is examined for compliance with the requirements placed onthe articles, a relatively small number of the articlesthe sampleisselected at random and is inspected. The inspection lot is then classified ascomplying or not complying with the requirements based on the results ofthe inspection of the sample. The size of t
