1、Designation: B 679 98 (Reapproved 2004)e1Standard Specification forElectrodeposited Coatings of Palladium for EngineeringUse1This standard is issued under the fixed designation B 679; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEWarning note updated and keywords added editorially in April 2004.1. Scope1.1 This specification covers requir
3、ements for electrodepos-ited palladium coatings containing at least 99.7 mass % 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 platinu
4、m 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 coatingand, consequently, some saving of metal weight accompaniedby a small sacrifice in corrosion resistance and reflectivity. Thefollowing
5、 table compares the hardness range of electrodepos-ited palladium with other 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 va
6、lues.Values provided in parentheses are for information only.1.4 This standard 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-
7、bility of regulatory limitations prior to use.2. Referenced Documents2.1 The following standards form a part of this specificationto the extent referenced herein:2.2 ASTM Standards:3B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Guide for Preparation of High-Carbon Steel f
8、orElectroplatingB 254 Practice for Preparation of and Electroplating onStainless SteelB 281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB 322 Practice for Cleaning Metals Prior to ElectroplatingB 343 Practice for Preparation of Nickel for Electr
9、oplatingwith NickelB 374 Terminology Relating to ElectroplatingB 481 Practice for Preparation of Titanium and TitaniumAlloys for ElectroplatingB 482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Micr
10、oscopical Examination of aCross SectionB 488 Specification for Electrodeposited Coatings of Goldfor Engineering UsesB 489 Practice for Bend Test for Ductility of Electrodepos-ited and Autocatalytically Deposited Metal Coatings onMetalsB 499 Test Method for Measurement of Coating Thick-nesses by the
11、Magnetic Method: Nonmagnetic Coatings onMagnetic Basis Metals1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.02 on Precious Metal Coatings.Current edition approved April 1, 2004. Published Ap
12、ril 2004. Originallyapproved in 1980. Last previous edition approved in 1998 as B 679 98.2The 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 servi
13、ceastm.org. For Annual Book of ASTMStandards 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.B 507 Practice for Design of Articles to Be Electroplate
14、d onRacksB 542 Terminology Relating to Electrical Contacts andTheir UseB 558 Practice for Preparation of Nickel Alloys for Electro-platingB 567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB 568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB 5
15、71 Practice for Qualitative Adhesion Testing of MetallicCoatingsB 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB 689 Specification for Electroplated Engineering NickelCoatingsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorgan
16、ic CoatingsB 741 Test Method for Porosity in Gold Coatings on MetalSubstrates by Paper ElectrographyB 748 Test Method for Measurement of Thickness of Me-tallic Coatings by Measurement of a Cross Section with aScanning Electron MicroscopeB 762 Test Method of Variables Sampling of Metallic andInorgani
17、c CoatingsB 765 Guide for Selection of Porosity and Gross DefectTests for Electrodeposits and Related Metallic CoatingsB 799 Test Method for Porosity in Gold and PalladiumCoatings by Sulfurous Acid/Sulfur-Dioxide VaporB 809 Test Method for Porosity in Metallic Coatings byHumid Sulfur Vapor (Flowers-
18、of-Sulfur)D 1125 Test Methods for Electrical Conductivity and Re-sistivity of WaterD 3951 Standard Practice for Commercial Packaging3. Terminology3.1 DefinitionsMany terms used in this specification aredefined in Terminology B 374 or B 542.3.2 Definitions of Terms Specific to This Standard:3.2.1 und
19、erplatinga metallic coating layer between thebasis metal or substrate and the topmost metallic coating. Thethickness 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 sha
20、ll specify the plating system, indicating thebasis metal, the thickness of the underplatings, the thickness ofthe palladium 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 ne
21、eds to supply the following infor-mation to the seller in the purchase order or other governingdocument:5.1.1 The name, 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,
22、type, and thickness of underplating (see3.2.3).5.1.4 Significant surfaces shall be defined (see 3.2.2).5.1.5 Requirements, 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,
23、 for surface coating cleanliness(absence of residual salts). See Appendix X3.6. Manufacture6.1 Any process that provides 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 t
24、his specification prior to the platingof the parts.6.2.2 Defects in the surface of the basis metal, such asscratches, 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
25、 of the best plating practice. Any such defects onsignificant surfaces should be brought to the attention of thesupplier and the purchaser.6.2.3 Clean the basis metal as necessary to ensure a satis-factory surface for subsequent electroplating in accordancewith Practices B 183, B 254, B 281, B 322,
26、B 343, B 481,B 482, and B 558, and Guide B 242.6.2.4 Proper preparatory procedures and thorough cleaningof the basis metal are essential for satisfactory adhesion andperformance of these coatings. The surface must be chemicallyclean and continuously conductive, that is, without inclusionsor other co
27、ntaminants. The coatings must be smooth and as freeof scratches, gouges, nicks, and similar imperfections aspossible.NOTE 1A metal finisher can often remove defects through specialTABLE 1 Thickness ClassAThickness Class Minimum Thickness of Pd (m)0.08 0.080.15 0.150.25 0.250.50 0.500.75 0.751.00 1.0
28、01.25 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 (99.7 % Au min) I 130-200
29、 HK25(C) 0.05-0.25 mASee Specification B 488 and Appendix X1.B 679 98 (2004)e12treatments 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
30、 Apply the coating after all basis metal preparatorytreatments and mechanical operations on significant surfaceshave been completed.6.4 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
31、the producer and supplier.6.5 Plating 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 s
32、ignals areemployed, such as wave guides, 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 app
33、lying the palla-dium.6.5.3 PlatingGood 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.
34、5.4 Stress CrackingProblems associated 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 tha
35、tpenetrate to the underlying substrate 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 pro
36、cess is necessary to preserve the performance 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 coefficien
37、t of friction.6.5.6 Residual SaltsFor 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 rinse
38、s and one runningrinse with dwell times 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 red
39、uced. See Appendix X3.7. Coating Requirements7.1 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 practicespe
40、rmit.7.3 ThicknessEverywhere on the 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 aminim
41、um requirement; that is, the coating 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 i
42、s an inherent characteristic of electroplating 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 thickn
43、ess on an article will be greater than the specifiedvalue; how much greater is largely determined by the shape of the article(see Practice B 507) and the characteristics of the plating process.In addition, the average coating thickness on articles will vary fromarticle to article within a production
44、 lot. Therefore, if all of the articles 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
45、 adherent tothe substrate, when tested 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 requ
46、irement may be relaxed to allow for 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 f
47、orany one type of coating will increase 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,
48、or away from the significant surfaces, 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
49、 befound in the literature (4, 5).8. 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 insp
