1、Designation: B488 11Standard 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 Department of Defense.1. Scope1.1 This specification covers requirements for electr
3、odepos-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 are auto-catalytic, immersion, and vapor deposited gold coatings.1.3 Gold coatings conforming to this specification are em-ployed for
4、 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 specification
5、.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 concern
6、s, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2B183 Practice for Preparation of Low-Carbon Ste
7、el 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 Copper and Copper-BaseAlloys for Electroplatin
8、g 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 ElectroplatingB482 Practice for Preparation
9、of Tungsten and TungstenAlloys for ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB489 Practice for Bend Test for Ductility of Electrodepos-ited and Autocatalytically Deposited Metal Coatings onMetalsB499 Test Method for
10、 Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Me-tallic Coatings by the Coulometric MethodB507 Practice for Design of Articles to Be Electroplated onRacksB542 Terminology Relating to Electrica
11、l 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-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of Meta
12、llicCoatingsB578 Test Method for Microhardness of ElectroplatedCoatingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB678 Test Method for Solderability of Metallic-CoatedProducts1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Co
13、atings and is the direct responsibility of SubcommitteeB08.08.02 on Precious Metal Coatings.Current edition approved Oct. 1, 2011. Published November 2010. Originallyapproved in 1968. Last previous edition approved in 2010 as B488 01(2010)e01.DOI: 10.1520/B0488-11.2For referenced ASTM standards, vis
14、it the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.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 19428-2
15、959, United States.B697 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 Coatings On MetalSubstrates By Paper Electrograph
16、y3B748 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 M
17、etallic 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 Co
18、mmercial 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 ofProduct2.3 ANSI/ASQC Standard:5ANSI/ASQC Z1.4 Sampling Procedu
19、res and Tables forInspection by Attributes3. Terminology3.1 DefinitionsFor definitions of terms used in this speci-fication refer to Terminologies B374 or B542, B374, and B542.3.2 Definitions of Terms Specific to This Standard:3.2.1 significant surfacesdefined as those normally vis-ible (directly or
20、 by reflection) or essential to the serviceabilityor function of the article. Can be the source of corrosionproducts or tarnish films that interfere with the function ordesirable appearance of the article. The significant surfacesshall be indicated on the drawings of the parts or by theprovision of
21、suitably 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 thinner.4. Classification4.1 Types of CoatingsA coa
22、ting 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 micrometres inaccordance with 4.3.4.2 Purity and Hardness:4.2.1 Purit
23、yThe issue of this standard establishes a newASTM Type designation, which is identical to the originalstandard (MIL-G-45204, which is now MIL-DTL-45204),established for electrodeposited gold and is outlined in thefollowing table.Mass Percent Gold, Minimum,Excluding Potassium, Carbon how much greater
24、 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. Therefore, if all the articles in a production lot are to meet thethick
25、ness 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 to thesubstrate when tested by one of the procedures summarized
26、 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 103. For someapplications this requirement may be relaxed to allow for asmall number of such defects (per unit
27、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 severity of the environment that the article islikely to encounter du
28、ring 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 particular article or coating requiring the porosity test (see9.6
29、 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 acceptance inspection. The sampling planused for the inspection of
30、 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 onthe articles, a relatively small number of the articles, the s
31、ample, 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 aredetermined by the application of statistics. The procedure is known assa
32、mpling inspection. Test Method B602, Guide B697, and Test MethodB488 114B762 contain sampling plans that are designed for the sampling inspectionof coatings. Test Method B602 contains four sampling plans, three for usewith tests that are nondestructive and one with those that are destructive.The pur
33、chaser 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 specified, the purchaser and supplier needto agree on the pl
34、an 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 contains several plans andalso gives instructions for calculating pl
35、ans 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 are of the same kind; that have beenproduced to the same specif
36、ications; 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 any recognized method to deter-mine quantitatively the metallic
37、 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 detect any unknown or unexpectedmetallic impurities. Determine de
38、posit 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 hardness should be determined onsamples at plating condition
39、s representative of actual produc-tion.9.3 AppearanceThe coating shall be examined at magni-fications up to 103 for conformance to the requirements ofappearance.9.4 Thickness and Mass per Unit AreaMeasure thicknessby methods outlined in Test Methods B487, B567, B568,orB748. The method chosen shall b
40、e 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 over the measured area. Thecross-sectioning and magnetic method
41、s measure the geometri-cal thickness of the gold present. Since many gold coatingshave a density lower than the theoretical density of gold (19.3g/cm3), instruments utilizing the measuring principles in TestMethods B504, B567, and B568 will often give lower readingsthan the microscopical cross-secti
42、on method. To convert massof gold per unit area that is present over the measured area toa geometrical thickness, it is necessary to use standards havinga density identical to that of the coatings to be measured, or tomultiply the reading obtained by factor, f.f 519.3d(1)where:d = density of gold co
43、ating, 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 measure-ments of thickness, shall be considered to be 19.3 g
44、/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 mass of gold per unit area (coating weight)directly and in
45、dependently 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 generallycertified in thickness units that can be converted to m
46、ass per unit area unitsby multiplying by the density of pure gold.Mass per unit area or coating weight!in mg/cm25 19.3 3 thickness m!/10 (2)This conversion should be verified by the supplier of thecalibration standards.9.5 AdhesionDetermine adhesion by one of the followingprocedures (see Practice B5
47、71 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 103. Cracking withoutseparation does not indicate poor adhesion
48、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 103 after the gold electroplatedparts are heated to 300 to 350C (570 to 660F) for 30 min andallowed to cool.9.5.3 Cutting TestMake a cut with a sharp
49、instrument andthen probe with a sharp point and examine at a magnificationof 103. No separation of the coating from the substrate shalloccur.9.6 Plating IntegrityPorosity shall be determined prefer-ably by either Test Method B735, B741, B799,orB809 unlessotherwise specified. See Guide B765 for guidelines for select-ing the appropriate test method.NOTE 14The test to be selected will depend upon the gold thickness,the nature of the basis metal, the nature and thickness of any intermediatelayers or underplate, the shape of the gold-coated part, and its int
