1、Designation: B488 18Standard Specification forElectrodeposited Coatings of Gold for Engineering Uses1This standard is issued under the fixed designation B488; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This specification covers requirements for e
3、lectrodepos-ited gold coatings that contain not less than 99.00 mass % goldand that are used for engineering applications.1.2 Specifically excluded from this specification areautocatalytic, immersion, and vapor deposited gold coatings.1.3 Gold coatings conforming to this specification are em-ployed
4、for their corrosion and tarnish resistance (includingresistance to fretting corrosion and catalytic polymerization),bondability, low and stable contact resistance, solderability,and infrared reflectivity. Several types of coatings, differing ingold purity and hardness, are covered by this specificat
5、ion.1.4 The values stated in SI units are to be regarded as thestandard. Values provided in parentheses are for informationonly.1.5 The following hazards caveat pertains only to the testmethods section, Section 9, of this specification: This standarddoes not purport to address all of the safety conc
6、erns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety, health, and environ-mental practices and determine the applicability of regulatorylimitations prior to use.1.6 This international standard was developed in accor-dance with int
7、ernationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B18
8、3 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB253 Guide for Preparation of Aluminum Alloys for Elec-troplatingB254 Practice for Preparation of and Electroplating onStainless SteelB281 Practice for Preparation of Co
9、pper 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 Preparation of Titanium and TitaniumAlloys for
10、ElectroplatingB482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB489 Practice for Bend Test for Ductility of Electrodepos-ited and Autocatalytically Deposited
11、 Metal Coatings onMetalsB499 Test Method for Measurement of Coating Thicknessesby the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Metal-lic Coatings by the Coulometric MethodB507 Practice for Design of Articles to Be Electroplated onR
12、acksB542 Terminology Relating to Electrical Contacts and TheirUseB558 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-Ray SpectrometryB571 Practic
13、e for Qualitative Adhesion Testing of MetallicCoatingsB578 Test Method for Microhardness of Electroplated Coat-ings1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatingsand is the direct responsibility of SubcommitteeB08.04 on Precious Metal Coatings.Cu
14、rrent edition approved Aug. 1, 2018. Published October 2018. Originallyapproved in 1968. Last previous edition approved in 2011 as B488 11. DOI:10.1520/B0488-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
15、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized
16、 principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1B602 Test Method for Attribute Sampling of Metallic andInorganic Coat
17、ingsB678 Test Method for Solderability of Metallic-CoatedProductsB697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB735 Test Method for Porosity in Gold Coatings on MetalSubstrates by Nitric Acid VaporB741 Test Method for Porosity In Gold Coa
18、tings On MetalSubstrates By Paper Electrography (Withdrawn 2005)3B748 Test Method for Measurement of Thickness of Metal-lic Coatings by Measurement of Cross Section with aScanning Electron MicroscopeB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB765 Guide for Selection of P
19、orosity and Gross Defect Testsfor Electrodeposits and Related Metallic 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 Electri
20、cal Conductivity and Resis-tivity of WaterD3951 Practice for Commercial PackagingF390 Test Method for Sheet Resistance of Thin MetallicFilms With a Collinear Four-Probe Array2.2 U.S. Government Standards:4MIL-DTL-45204 Gold Plating, ElectrodepositedMIL-STD-1916 DOD Preferred Methods for Acceptance o
21、fProduct2.3 ANSI/ASQC Standard:5ANSI/ASQC Z1.4 Sampling Procedures and Tables for In-spection by Attributes3. Terminology3.1 DefinitionsFor definitions of terms used in this speci-fication refer to Terminologies B374 or B542.3.2 Definitions of Terms Specific to This Standard:3.2.1 significant surfac
22、esdefined as those normally visible(directly or by reflection) or essential to the serviceability orfunction of the article. Can be the source of corrosion productsor tarnish films that interfere with the function or desirableappearance of the article. The significant surfaces shall beindicated on t
23、he drawings of the parts or by the provision ofsuitably marked samples.3.2.2 underplatinga 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, which is thin
24、ner.4. Classification4.1 Types of CoatingsA coating shall be specified by acombination of the following:4.1.1 Type, characterizing minimum purity in accordancewith 4.2.1,4.1.2 Code, designating Knoop hardness in accordance with4.2.3, and4.1.3 a numeral designating thickness in micrometers (m)in acco
25、rdance with 4.3.4.2 Purity and Hardness:4.2.1 PurityThe 2001 issue of this standard establishednew ASTM Type designations, which are identical to theoriginal standard (MIL-G-45204, which is now MIL-DTL-45204), established for electrodeposited gold and they areoutlined in the following table.Mass Per
26、cent Gold, Minimum,Excluding Potassium, Carbon how much greater islargely determined by the shape of the article (see Practice B507) and thecharacteristics of the plating process. In addition, the average coatingthickness on articles will vary from article to article within a productionlot. Therefor
27、e, if all the articles in a production lot are to meet thethickness requirement, the average coating thickness for the production lotas a whole will be greater than the average necessary to ensure that anysingle article meets the requirement (see 8.1).7.5 AdhesionThe gold coatings shall be adherent
28、to thesubstrate when tested by one of the procedures summarized in9.5.7.6 Integrity of the Coating:7.6.1 Gross Defects/Mechanical DamageThe coatingsshall be free of visible mechanical damage and similar grossdefects when viewed at magnifications up to 10. For someapplications this requirement may be
29、 relaxed to allow for asmall number of such defects (per unit area), especially if theyare outside or on the periphery of the significant surfaces (see7.6.2).7.6.2 PorosityAlmost all as-plated electrodeposits containsome porosity. The tolerable amount of porosity in the coatingdepends on the severit
30、y of the environment that the article islikely to encounter during service or storage. If the pores arefew in number or away from the significant surfaces, theirpresence can often be tolerated. Such acceptance (or pass-fail)criteria, if required, shall be part of the product specification forthe par
31、ticular article or coating requiring the porosity test (see9.6 for porosity testing).8. Sampling8.1 The supplier is urged to employ statistical processcontrol in the coating process. Properly performed, this processwill ensure coated products of satisfactory quality and willreduce the amount of acce
32、ptance inspection.The sampling planused for the inspection of the quality of the coated articles shallbe as agreed upon between the purchaser and the supplier.NOTE 12Usually, with a collection of coated articles, the inspectionlot (see 8.2) is examined for compliance with the requirements placed onB
33、488 184the articles, a relatively small number of the articles, the sample, isselected at random and is inspected. The inspection lot is then classified ascomplying with the requirements based on the results of the inspection ofthe sample. The size of the sample and the criteria of compliance aredet
34、ermined by the application of statistics. The procedure is known assampling inspection. Test Method B602, Guide B697, and Test MethodB762 contain sampling plans that are designed for the sampling inspectionof coatings. Test Method B602 contains four sampling plans, three for usewith tests that are n
35、ondestructive and one with those that are destructive.The purchaser and supplier may agree on the plan or plans to be used. Ifthey do not, Test Method B602 identifies the plan to be used. Guide B697provides a large number of plans and also gives guidance in the selectionof a plan. When Guide B697 is
36、 specified, the purchaser and supplier needto agree on the plan to be used. Test Method B762 can be used only forcoating requirements that have a numerical limit, such as coatingthickness. The test must yield a numerical value and certain statisticalrequirements must be met. Test Method B762 contain
37、s several plans andalso gives instructions for calculating plans to meet special needs. Thepurchaser and supplier may agree on the plan or plans to be used. If theydo not, Test Method B762 identifies the plan to be used.8.2 An inspection lot shall be defined as a collection ofcoated articles that ar
38、e of the same kind; that have beenproduced to the same specifications; that have been coated bya single supplier at one time, or at approximately the sametime; under essentially identical conditions; and that aresubmitted for acceptance or rejection as a group.9. Test Methods9.1 Deposit PurityUse an
39、y recognized method to deter-mine quantitatively the metallic impurities present. Atomicabsorption spectrophotometry (or any methods with demon-strated uncertainty less than 10 %) may be used to determinethe metallic impurities. Initial scanning should be carried outfor all elements in order to dete
40、ct any unknown or unexpectedmetallic impurities. Determine deposit purity by subtractingtotal impurities in mass from 100 %. Deposit purity should bedetermined on samples at plating conditions representative ofactual production.9.2 HardnessMeasure hardness in accordance with TestMethod B578. Deposit
41、 hardness should be determined onsamples at plating conditions representative of actual produc-tion.9.3 AppearanceThe coating shall be examined at magni-fications up to 10 for conformance to the requirements ofappearance.9.4 Thickness and Mass per Unit AreaMeasure thicknessby methods outlined in Tes
42、t Methods B487, B567, B568,orB748. The method chosen shall be such as to give anuncertainty of less than 10 % on the particular coating beingmeasured.9.4.1 ThicknessThe beta backscatter, X-ray fluorescencespectrometry, and coulometric methods measure the mass ofgold per unit area that is present ove
43、r the measured area. Thecross-sectioning and magnetic methods measure the geometri-cal thickness of the gold present. Since many gold coatingshave a density lower than the theoretical density of gold(19.3 gcm3), instruments utilizing the measuring principles inTest Methods B504, B567, and B568 will
44、often give lowerreadings than the microscopical cross-section method. Toconvert mass of gold per unit area that is present over themeasured area to a geometrical thickness, it is necessary to usestandards having a density identical to that of the coatings to bemeasured, or to multiply the reading ob
45、tained by factor, f.f 519.3d(1)where:d = density of gold coating, g/cm3.9.4.1.1 The density of gold coatings depends not only on thetype of gold coating but also on the gold content and thecomposition and purity of the electroplating solution. Thedensity figure, when the above methods are used for m
46、easure-ments of thickness, shall be considered to be 19.3 g/cm3forType III coatings and 17.5 g/cm3for Type I and Type IIcoatings, unless:(1) the density is supplied by the plating process vendor, or(2) the density has been measured.9.4.2 Mass Per Unit AreaTest Methods B504, B567, andB568 measure the
47、 mass of gold per unit area (coating weight)directly and independently of the density of gold.NOTE 13The calibration standards available from the National Insti-tute of Standards and Technology (NIST)8are certified in units of mass ofgold per unit area. Other calibration standards for gold are gener
48、allycertified in thickness units that can be converted to mass per unit area unitsby multiplying by the density of pure gold.Mass per unit area or coating weight! (2)in mg/cm25 19.3 3thickness m!/10This conversion should be verified by the supplier of thecalibration standards.9.5 AdhesionDetermine a
49、dhesion by one of the followingprocedures (see Practice B571 for full details).9.5.1 Bend TestBend the electroplated article repeatedlythrough an angle of 180 on a diameter equal to the thicknessof the article until fracture of the basis metal occurs. Examinethe fracture at a magnification of 10. Cracking withoutseparation does not indicate poor adhesion unless the coatingcan be peeled back with a sharp instrument.9.5.2 Heat TestNo flaking, blistering, or peeling shall beapparent at a magnification of 10 after the gold electroplatedparts are heated to
