ASTM_B_545-13.pdf

Designation:B545-13NTERNATIONALStandard Specification forElectrodeposited Coatings of Tin1This standard is issued under the fixed designation B545:the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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.This standard has been approved for use by agencies of the Department of Defense.1.Scope2.Referenced Documents1.1 This specification covers the requirements for electrode-2.1 ASTM Standards:2posited(electroplated)coatings of tin applied to metallicA623 Specification for Tin Mill Products,General Require-articles.Tin coatings are used to provide a low contact-mentsresistance surface,to protect against corrosion(see 1.2),toA623M Specification for Tin Mill Products,General Re-facilitate soldering,to provide anti-galling properties,and to bequirements Metrica stopoff coating in the nitriding of high-strength steels.B32 Specification for Solder Metal1.2 Some corrosion can be expected from tin coatingsB183 Practice for Preparation of Low-Carbon Steel forexposed outdoors.In normal indoor exposure,tin is protectiveElectroplatingon iron,steel,nickel,copper,and their alloys.Corrosion can beB242 Guide for Preparation of High-Carbon Steel for Elec-expected at discontinuities in the coating(such as pores)due totroplatinggalvanic couples formed between the tin and the underlyingB246 Specification for Tinned Hard-Drawn and Medium-metal through the discontinuities,especially in humid atmo-Hard-Drawn Copper Wire for Electrical Purposesspheres.Porosity increases as the coating thickness decreases,B281 Practice for Preparation of Copper and Copper-Baseso that minimum thicknesses must be specified for eachAlloys for Electroplating and Conversion Coatingsapplication.Parts coated with tin can be assembled safely inB320 Practice for Preparation of Iron Castings for Electro-contact with iron and steel,tin-coated aluminum,yellowplatingchromated zinc,cadmium,and solder coatings.(See X5.1 forB322 Guide for Cleaning Metals Prior to Electroplatingoxidation and corrosion properties.)B374 Terminology Relating to ElectroplatingB487 Test Method for Measurement of Metal and Oxide1.3 This specification applies to electroplated coatings ofCoating Thickness by Microscopical Examination ofnot less than 99 tin(except where deliberately alloyed forCross Sectionspecial purposes,as stated in X6.3)obtained from any of theB499 Test Method for Measurement of Coating Thicknessesavailable tin electroplating processes(see 4.3).by the Magnetic Method:Nonmagnetic Coatings on1.4 This specification does not apply to hot-dipped tin orMagnetic Basis Metalsother non-electrodeposited coating;it also does not apply toB504 Test Method for Measurement of Thickness of Metal-mill products.For mill products,refer to Specifications A623lic Coatings by the Coulometric Methodor A623M.B507 Practice for Design of Articles to Be Electroplated on1.5 The values stated in SI units are to be regarded as theRacksstandard.The values given in parentheses are for informationB542 Terminology Relating to Electrical Contacts and TheirUseonly.B558 Practice for Preparation of Nickel Alloys for Electro-1.6 This standard does not purport to address all of theplatingsafety concerns,if any,associated with its use.It is theB567 Test Method for Measurement of Coating Thicknessresponsibility of the user of this standard to establish appro-by the Beta Backscatter Methodpriate safety and health practices and determine the applica-B568 Test Method for Measurement of Coating Thicknessbility of regulatory limitations prior to use.by X-Ray SpectrometryThis specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.06 on Soft Metals.2 For referenced ASTM standards,visit the ASTM website,www.astm.org.orCurrent edition approved May 1,2013.Published July 2013.Originally approvedcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMin 1971.Last previous edition approved in 2009 as B545-97(2009).DOI:Standards volume information,refer to the standards Document Summary page on10.1520/B0545-13.the ASTM website.Copyright ASTM Intemational,100 Barr Harbor Drive,PO Box C700.West Conshohocken.PA 19428-2959.United StatesB545-13B571 Practice for Qualitative Adhesion Testing of Metallic4.2 Service Class:CoatingsClassMinimum ThicknessTypical ApplicationsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsA2.5um(100in.)Mild service conditions,particularly where thesignificant surface is shielded from theB659 Guide for Measuring Thickness of Metallic and Inor-atmosphere(as in electronic connectorganic Coatingshousings).To provide corrosion and tamishB678 Test Method for Solderability of Metallic-Coatedresistance where greater thicknesses may bedetrimental to the mechanical operation of theProductsproduct(for example,small electrical springB697 Guide for Selection of Sampling Plans for Inspectioncontacts and relays).Class A is often used forof Electrodeposited Metallic and Inorganic Coatingstin coatings that are not to be soldered,butmust function as low-resistance electricalB762 Test Method of Variables Sampling of Metallic andcontact surtaces.Inorganic CoatingsB 5 um(200 uin.)Mild service conditions with less severeB765 Guide for Selection of Porosity and Gross Defect Testsrequirements than Class C(below).Applications are as follows:precoating onfor Electrodeposits and Related Metallic Coatingssolderable basis metals to facilitate theB809 Test Method for Porosity in Metallic Coatings bysoldering of electrical components;as a surfaceHumid Sulfur Vapor(Flowers-of-Sulfur)preparation for protective painting;forantigalling purposes;and as a stopoff inB849 Specification for Pre-Treatments of Iron or Steel fornitriding.Also found on baking pans afterReducing Risk of Hydrogen Embrittlementreflow.B850 Guide for Post-Coating Treatments of Steel for Reduc-C8m(320in.),Moderate exposure conditions,usually indoors(10m(400in.)but more severe than Class B.Examples areing the Risk of Hydrogen Embrittlementfor steel substrates)electrical hardware(such as cases for relaysB851 Specification for Automated Controlled Shot Peeningand coils,transformer cans,screened cages,chassis,frames,and fittings)and for retentionof Metallic Articles Prior to Nickel,Autocatalytic Nickel,of the solderability of solderable articles duringor Chromium Plating,or as Final Finishstorage.D3951 Practice for Commercial PackagingD15um(600n.)Severe service,including exposure to(20um(800uin.)dampness and mild corrosion from moderate3.Terminologyfor steel substrates)industrial environments.Examples are fittingsfor gas meters,automotive accessories(such3.1 Definitions:as air cleaners and oil filters).and in some3.1.1 Many of the terms used in this specification areelectronic applications.E30m(0.0012in.)Very severe service conditions,includingdefined in Terminology B374 or B542.elevated temperatures,where underlying metal3.1.2 rack-plating-an electrodeposition process in whichdiffusion and intermetallic formation processesare accelerated.Thicknesses of 30 to 125 umarticles to be coated are mounted on racks or other fixtures(0.0012 to 0.005 in.)may be required if theduring the process.coating is subjected to abrasion or is exposed3.1.3 significant surface-that portion of the surface of ato slowty corrosive liquids or corrosiveatmospheres or gases.Thicker coatings arecoated article at which the coating is required to meet all of theused for water containers,threaded steelrequirements of the coating specification for that article;couplings of oil drilling strings,and seacoastatmospheres.Coatings subject to mild etchantssignificant surfaces are usually those that are essential to theare included.serviceability or function of the article,or that can be a sourceF1.5um(60in.)Similar to Class A,but for shorter-term contactof corrosion products or tarnish films that interfere with theapplications and short shelf-life requirements,subject to purchaser approval.function or desirable appearance of the article;significantsurfaces shall be indicated on the drawings of the parts or by4.3 Surface Appearance Type(Electroplating Process):the provision of suitably marked samples.4.3.1 Matte Tin Electrodeposits-Coatings with a matte3.1.4 undercoating(see 3.1.5)-also called an underplate inappearance are obtained from tin plating baths(stannate,the electronics industry.sulfate,methylsulfonate.and fluoborate)used without the3.1.5 underplating-application of a metallic coating layeraddition of any brightening agents.However,all matte baths(except for stannate baths)do require the addition of grain-between the basis metal or substrate and the topmost metallicrefiners,and often of other additives in order to produce thecoating or coatings.The thickness of such an undercoating isdesired matte finish.usually greater than 0.8 um(30 uin.).This is in contrast tostrikes or flashes,whose thicknesses are generally much4.3.2 Bright Tin Electrodeposits-Bright coatings are ob-smaller.tained when proprietary brightening agents are used in specificbright tin plating baths.4.Classification4.3.3 Flow-Brightened Electrodeposits-Flow-brightened4.1 General-Orders for articles to be plated in accordancecoatings are obtained by heating the matte coating above thewith this specification shall specify the service class(4.2)(andmelting point of tin for a few seconds,followed by quenching;underplating,if required),indicating the severity of servicepalm oil and hydrogenated oils and fats are used as heat-required for the coating.Other coatings variations,such astransfer medium at a temperature of 240 to 260C(464 tosurface appearance type(4.3)or alloy composition(Appendix500F),but other heating methods also are in use,such as hotX6),are optional.air.The maximum thickness for flow-brightening is,in mostB545-136.10 Deposit Purity-The tin coating shall be not less thansame conditions as typical production pieces99 tin,when tested in accordance with 8.1.Deliberate8.2 Thickness:alloying for special purposes shall only be allowed when8.2.1 Standard Thickness-The coating thickness shall bespecifically agreed upon between the purchaser and seller(seemeasured at locations on significant surfaces by one of theX6.3).following test methods:Test Methods B487,B499(magnetic7.Samplingsubstrates only),B504,B567,and B568.Practice B659 may beconsulted to determine the most appropriate test method.7.1 The sampling plan used for inspection of a quantity of8.2.1.1 When Methods B504 and B568 are used with tinthe coated articles shall be as agreed upon between theplatings that have been alloyed with more than 0.5%of leadpurchaser and the supplier.bismuth,or antimony to reduce whiskering(see X6.3.2.5),theNorE 6-The procedure for sampling is accomplished by selecting astandard shall have the same composition as the coating.Whenrelatively small number of the finished articles at random.These articlesTest Method B567 is used to measure these types of coatings,(the inspection lots)are inspected and classified as complying or notthe measuring instrument shall be calibrated with thicknesscomplying with the requirements of the specification.The size of thestandards that have the same substrate and same compositionsample and the criteria of compliance are determined by the application ofof coating as the product.statistics.The procedure is known as sampling inspection.Threestandards,Test Method B602,Guide B697,and Test Method B762.8.2.2 Mean Thickness-If the entire surface of the article iscontain sampling plans that are designed for the sampling inspection ofa significant surface,the mean thickness can also be deter-coatings.mined by the method described in Appendix X1.Also see NoteTest Method B602 contains four sampling plans,three for use with tests5that are non-destructive and one for use when they are destructive.Thebuyer and seller may agree on the plan or plans to be used.If they do not,8.3 Adhesion-Adhesion of the coating shall be tested byTest Method B602 identifies the plan to be used.one of the recommended methods of Practice B571(seeGuide B697 provides a large number of plans and also providesguidance in the selection of a plan.When Guide B697 is specified,theAppendix X2).buyer and seller must agree on the plan to be used.8.4 Solderability-For coatings that must be solderable,theTest Method B762 can be used only for coating requirements that havemethod by which solderability is tested shall be specified.a numerical limit,such as coating thickness.The test must yield aThree test methods are described in Appendix X3,while anumerical value,and certain statistical requirements must be met.TestMethod B762 contains several plans and also provides instructions forsimple dip test is given in Test Method B678.The purchasercalculating plans to meet special needs.The buyer and seller may agree onshall specify whether the tested articles are to receive anthe plan or plans to be used.If they do not,Test Method B762 identifiesartificial aging treatment,such as that given in Test Methodthe plan to be used.B678,so as to demonstrate whether the articles may be7.2 An inspection lot shall be defined as a collection ofexpected to retain their solderability during long storagecoated articles that meet the following requirements:they areperiodsof the same kind:have been produced to the same specifica-8.5 Porosity and Gross Defects Testing:tions;have been coated by a single supplier at one time,or at8.5.1 Coatings on articles of steel(or iron)having a localapproximately the same time,under essentially identical con-thickness of 10 u(0.4 mil)or greater should be subjected to theditions;and are submitted for acceptance or rejection as atest given in Appendix X5.group.8.5.2 For coatings on articles made from copper or copper7.3 Special Test Specimens-It may be preferable to usealloy as the basis metal,the following tests should be used:special test specimens to represent product in process control8.5.2.1 To determine mechanical damage or gross defectsor in acceptance inspection when,for example,destructiveonly,subject samples to the sodium polysulfide immersion testtests are used and it is desirable not to destroy product or if theoutlined in Specification B246.Black spots or lines aretest specimen is better adapted to the test.The use of specialevidence of mechanical damage or gross defects.test specimens,their number,the material from which they are8.5.2.2 To determine all porosity that penetrates down to themade,their size and shape,and the conditions of their coatingcopper substrate,especially for coatings in Service Class A,theshall be as agreed upon by the purchaser and the seller.humid sulfur vapor test(Test Method B809)shall be used.Blackening at pores will be evidence of porosity.8.Test Methods8.1 Deposit Purity-Atomic absorption or energy dispersion9.Rejection and Rehearingspectrophotometry,or any other methods with a demonstrated9.1 Articles that fail to conform to the requirements of thisuncertainty of less than 10 of the component measured,mayspecification may be rejected.Rejection shall be reported to thebe used to determine impurities.Initial scanning should beseller promptly and in writing.In cases of rejection,the sellerconducted for all elements in order to detect any unknown ormay make a claim for a rehearing.Product that shows coatingunexpected impurities.Determine deposit purity by subtractingimperfections in subsequent manufacturing operations may bethe total impurities from 100%rejected.NorE 7-Deposit purity is best determined on samples of the actual10.Keywordsproduct(see Section 7).If special test specimens are used(7.3),care mustbe taken to arrange the specimens so as to electroplate them under the10.1 electrodeposited tin;electroplated tin;tin;tin coatingsB545-13SUPPLEMENTARY REOUIREMENTSThe following supplementary requirements shall apply only when specified by the purchaser in thecontract or order.S1.Pretreatment of Iron and Steel for Reducing the Riskpost coating hydrogen embrittlement relief baking when speci-of Hydrogen Embrittlementfied by the purchaser,the tensile strength to be supplied by theS1.1 Parts for critical applications that are made of steelspurchaser.Specifications B850 may be consulted for a list ofwith ultimate tensile strengths of 1000 MPa,hardness of 31post treatments that are used widely.HRC or greater,that have been machined,ground,coldformed,or cold straightened subsequent to heat treatment,shallS3.Solderability Requirementsrequire stress relief treatment when specified by the purchaser,S3.1 If the coating must be solderable,refer to 8.4 for testthe tensile strength to be supplied by the purchaser.Specifica-methods for determining solderability.tions B849(heat treatment)and B851(shot peening)may beconsulted for a list of pretreatments that are used widely.S4.Government Packaging RequirementsS2.Post Coating Treatments of Iron and Steel for Reduc-S4.1 Parts plated for the U.S.government and military,ing the Risk of Hydrogen Embrittlementincluding subcontractors,shall be packaged according to Prac-S2.1 Parts for critical applications that are made of steelstice D3951.(Warning-Some contemporary packaging mate-with ultimate tensile strengths of 1000 MPa,hardness of 31rials may emit fumes that are deleterious to the surface of theHRC or greater,as well as surface hardened parts,shall requirecoating.)APPENDIXES(Nonmandatory Information)X1.DETERMINATION OF MEAN COATING THICKNESS OF SMALL ARTICLES BY THE WEIGHT LOSS METHODX1.1 Select at random from the production lot the numberand allow them to remain for I min after gas evolution stops.of coated articles specified by the purchaser.The number ofRemove the articles,rinse them in clean water,wipe and brusharticles shall be sufficient to have a total weight of coating ofas necessary to remove smut(antimony residues),and dry.at least 0.2 g.Calculate the coated area in mm-to an accuracyReweigh.of at least 1 part in 100.X1.2 Clean the articles by,for example,washing in aX1.4 Calculate the mean thickness in um by dividing theloss in weight of the articles by the area and multiplying thesolvent or water-detergent followed by a clean water rinse.Dryand weigh with an accuracy of at least 1 part in 1000.quotient by1.37105.X1.3 Immerse the articles in a solution of 20 g antimonytrioxide in 1 L of concentrated hydrochloric acid(sp gr 1.19)X2.ADHESION TESTSX2.1 Burnishing Test-Rub an area of not more than 630crack,and the plating will peel away from the basis metal.mm(1 in.)of the electroplated surface,selected at thediscretion of the inspector,rapidly and firmly for 15 s with aX2.2 Quenching Test-Heat the electroplated article in ansmooth metal implement.A suitable burnishing implement is aoven for a sufficient time to reach15010C(30020F),copper or steel disk used edgewise and broadside.Maintainand then quench in water at room temperature.Poor adhesionwill be shown if the coating blisters,cracks,or peels.pressure sufficient to burnish the film at every stroke,but not sogreat as to cut the deposit.Poor adhesion will be shown by theX2.3 Reflow Test-Parts may be evaluated by reflowing in aappearance of a loose blister that grows as rubbing is contin-bath of palm oil at a temperature of 235 to 260C(455 toued.If the quality of the deposit is also poor,the blister may500F)until the plating melts.A bright coating completely5