1、Designation: B545 13Standard 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 parenth
2、eses 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 the requirements for electrode-posited (elect
3、roplated) coatings of tin applied to metallicarticles. Tin coatings are used to provide a low contact-resistance surface, to protect against corrosion (see 1.2), tofacilitate soldering, to provide anti-galling properties, and to bea stopoff coating in the nitriding of high-strength steels.1.2 Some c
4、orrosion can be expected from tin coatingsexposed outdoors. In normal indoor exposure, tin is protectiveon iron, steel, nickel, copper, and their alloys. Corrosion can beexpected at discontinuities in the coating (such as pores) due togalvanic couples formed between the tin and the underlyingmetal t
5、hrough the discontinuities, especially in humid atmo-spheres. Porosity increases as the coating thickness decreases,so that minimum thicknesses must be specified for eachapplication. Parts coated with tin can be assembled safely incontact with iron and steel, tin-coated aluminum, yellowchromated zin
6、c, cadmium, and solder coatings. (See X5.1 foroxidation and corrosion properties.)1.3 This specification applies to electroplated coatings ofnot less than 99 % tin (except where deliberately alloyed forspecial purposes, as stated in X6.3) obtained from any of theavailable tin electroplating processe
7、s (see 4.3).1.4 This specification does not apply to hot-dipped tin orother non-electrodeposited coating; it also does not apply tomill products. For mill products, refer to Specifications A623or A623M.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parenthes
8、es are for informationonly.1.6 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-bility of regulatory limitations p
9、rior to use.2. Referenced Documents2.1 ASTM Standards:2A623 Specification for Tin Mill Products, General Require-mentsA623M Specification for Tin Mill Products, General Re-quirements MetricB32 Specification for Solder MetalB183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide
10、 for Preparation of High-Carbon Steel for Elec-troplatingB246 Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire for Electrical PurposesB281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB320 Practice for Preparation of Iron Cas
11、tings for Electro-platingB322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology Relating to ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB499 Test Method for Measurement of Coating Thicknessesby the Mag
12、netic 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 onRacksB542 Terminology Relating to Electrical Contacts and TheirUseB558 Practice for Prepar
13、ation 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 Spectrometry1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings
14、 and is the direct responsibility of SubcommitteeB08.06 on Soft Metals.Current edition approved May 1, 2013. Published July 2013. Originally approvedin 1971. Last previous edition approved in 2009 as B545 97 (2009). DOI:10.1520/B0545-13.2For referenced ASTM standards, visit the ASTM website, www.ast
15、m.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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1B571 Pract
16、ice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB659 Guide for Measuring Thickness of Metallic and Inor-ganic CoatingsB678 Test Method for Solderability of Metallic-CoatedProductsB697 Guide for Selection of Sampling Pla
17、ns for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB765 Guide for Selection of Porosity and Gross Defect Testsfor Electrodeposits and Related Metallic CoatingsB809 Test Method for Porosity in Metallic Coatings b
18、yHumid Sulfur Vapor (“Flowers-of-Sulfur”)B849 Specification for Pre-Treatments of Iron or Steel forReducing Risk of Hydrogen EmbrittlementB850 Guide for Post-Coating Treatments of Steel for Reduc-ing the Risk of Hydrogen EmbrittlementB851 Specification for Automated Controlled Shot Peeningof Metalli
19、c Articles Prior to Nickel, Autocatalytic Nickel,or Chromium Plating, or as Final FinishD3951 Practice for Commercial Packaging3. Terminology3.1 Definitions:3.1.1 Many of the terms used in this specification aredefined in Terminology B374 or B542.3.1.2 rack-platingan electrodeposition process in whi
20、charticles to be coated are mounted on racks or other fixturesduring the process.3.1.3 significant surfacethat portion of the surface of acoated article at which the coating is required to meet all of therequirements of the coating specification for that article;significant surfaces are usually thos
21、e that are essential to theserviceability or function of the article, or that can be a sourceof corrosion products or tarnish films that interfere with thefunction or desirable appearance of the article; significantsurfaces shall be indicated on the drawings of the parts or bythe provision of suitab
22、ly marked samples.3.1.4 undercoating (see 3.1.5)also called an underplate inthe electronics industry.3.1.5 underplatingapplication of a metallic coating layerbetween the basis metal or substrate and the topmost metalliccoating or coatings. The thickness of such an undercoating isusually greater than
23、 0.8 m (30 in.). This is in contrast tostrikes or flashes, whose thicknesses are generally muchsmaller.4. Classification4.1 GeneralOrders for articles to be plated in accordancewith this specification shall specify the service class (4.2) (andunderplating, if required), indicating the severity of se
24、rvicerequired for the coating. Other coatings variations, such assurface appearance type (4.3) or alloy composition (AppendixX6), are optional.4.2 Service Class:Class Minimum Thickness Typical ApplicationsA 2.5 m (100 in.) Mild service conditions, particularly where thesignificant surface is shielde
25、d from theatmosphere (as in electronic connectorhousings). To provide corrosion and tarnishresistance where greater thicknesses may bedetrimental to the mechanical operation of theproduct (for example, small electrical springcontacts and relays). Class A is often used fortin coatings that are not to
26、 be soldered, butmust function as low-resistance electricalcontact surfaces.B 5 m (200 in.) Mild service conditions with less severerequirements than Class C (below).Applications are as follows: precoating onsolderable basis metals to facilitate thesoldering of electrical components; as a surfacepre
27、paration for protective painting; forantigalling purposes; and as a stopoff innitriding. Also found on baking pans afterreflow.C 8 m (320 in.),(10 m (400 in.)for steel substrates)Moderate exposure conditions, usually indoors,but more severe than Class B. Examples areelectrical hardware (such as case
28、s for relaysand coils, transformer cans, screened cages,chassis, frames, and fittings) and for retentionof the solderability of solderable articles duringstorage.D 15 m (600 in.)(20 m (800 in.)for steel substrates)Severe service, including exposure todampness and mild corrosion from moderateindustri
29、al environments. Examples are fittingsfor gas meters, automotive accessories (suchas air cleaners and oil filters), and in someelectronic applications.E 30 m (0.0012 in.) Very severe service conditions, includingelevated temperatures, where underlying metaldiffusion and intermetallic formation proce
30、ssesare accelerated. Thicknesses of 30 to 125 m(0.0012 to 0.005 in.) may be required if thecoating is subjected to abrasion or is exposedto slowly corrosive liquids or corrosiveatmospheres or gases. Thicker coatings areused for water containers, threaded steelcouplings of oil drilling strings, and s
31、eacoastatmospheres. Coatings subject to mild etchantsare included.F 1.5 m (60 in.) Similar to Class A, but for shorter-term contactapplications and short shelf-life requirements,subject to purchaser approval.4.3 Surface Appearance Type (Electroplating Process):4.3.1 Matte Tin ElectrodepositsCoatings
32、 with a matteappearance are obtained from tin plating baths (stannate,sulfate, methylsulfonate, and fluoborate) used without theaddition of any brightening agents. However, all matte baths(except for stannate baths) do require the addition of grain-refiners, and often of other additives in order to
33、produce thedesired matte finish.4.3.2 Bright Tin ElectrodepositsBright coatings are ob-tained when proprietary brightening agents are used in specificbright tin plating baths.4.3.3 Flow-Brightened ElectrodepositsFlow-brightenedcoatings are obtained by heating the matte coating above themelting point
34、 of tin for a few seconds, followed by quenching;palm oil and hydrogenated oils and fats are used as heat-transfer medium at a temperature of 240 to 260C (464 to500F), but other heating methods also are in use, such as hotair. The maximum thickness for flow-brightening is, in mostB545 132cases, appr
35、oximately 8 m (300 in.). The shape of the part isalso a factor; flat surfaces dewet more readily than wires orrounded shapes.NOTE 1Terms commonly used in soldering, such as dewet, aredescribed in soldering textbooks (1)3or reviews of solderability testing(2). Some examples are given in Appendix X6.5
36、. Ordering Information5.1 In order to make the application of this specificationcomplete, the purchaser must supply the following informationto the seller in the purchase order and drawings:5.1.1 Title, ASTM designation number, and year of issue ofthis specification;5.1.2 Deposit by classification (
37、4.1), including thickness orservice class (4.2);5.1.3 Composition and metallurgical condition of the sub-strate to be coated (6.1);5.1.4 Additional underplating, if required (6.8);5.1.5 Surface-appearance type (for example, matte, flow-brightened, or bright), if required (4.3 and 6.2);5.1.6 Location
38、 of significant surfaces (3.1.3);5.1.7 Hydrogen embrittlement relief, if required (Supple-mentary Requirement S2); and5.1.8 Any other items needing agreement (for example,6.5.2, 8.4 and 8.5).6. Coating Requirements6.1 SubstrateThe metal substrate shall be subjected tosuch surface preparation, cleani
39、ng, and electroplating proce-dures as are necessary to yield deposits with the desiredquality.NOTE 2Careful preparation of metal surfaces is necessary in order toassure good adhesion and quality. For suitable methods, see PracticesB183, B242, B281, B320, B322, and B558. Also see 6.6.6.2 Electroplati
40、ng shall be applied after all basis metal heattreatments and mechanical operations have been completed.6.3 AppearanceTin coatings shall have the characteristicappearance, including surface texture (4.3), for the processused. The appearance shall be uniform throughout, insofar asthe basis metal will
41、permit. They shall be adherent and visuallyfree of blisters, pits, peeled areas, cracks, nodules, and unplatedareas. They shall not be stained or discolored. Flow-brightenedcoatings shall be free of dewetted areas and beads.All surfacesshall be substantially free of grease or oil used in theflow-bri
42、ghtening process.6.4 All tin-coated articles shall be clean and undamaged.When necessary, preliminary samples showing the finish shallbe supplied to and approved by the purchaser. Where a contactmark is inevitable, its location shall be subject to agreementbetween the supplier and the purchaser.6.5
43、Thickness of CoatingsTin coatings on articles shallconform to the thickness requirements specified in 4.2 as to theminimum thickness on significant surfaces.6.5.1 Local ThicknessThe thickness values specified in4.2 are the minimum local thicknesses measured by one ormore of the methods given in Prac
44、tice B659 at any number ofdesired spots on the significant surface.6.5.2 Mean ThicknessWhen specified by the purchaser,instead of being a local minimum requirement, the thicknessrequirement can be a minimum (arithmetic) mean thickness.NOTE 3Specification of the coating thickness in terms of the mean
45、 isnormally made when the coated articles are small and relatively simple,such as connector pins and terminals.NOTE 4Thickness of electrodeposited coatings varies from point topoint on the surfaces of a product (see Practice B507). The thickness isless in interior corners and holes. Such surfaces ar
46、e normally exempt fromthe thickness requirement. If the full thickness is required on thesesurfaces, the electroplater will have to use special techniques that probablywill increase the cost of the process.NOTE 5When articles are plated by mass plating techniques (such asbarrel plating), such measur
47、ement methods as “strip and weigh” or “weighbefore and after plating” may be used to determine the mean thickness.6.6 AdhesionAdhesion of the coating shall be tested byone of the methods given in Practice B571. The coating shouldadhere to the basis metal when subjected to the agreed test;flaking or
48、blistering of the coating is to be taken as evidence ofunsatisfactory adhesion.6.7 Integrity of the Coating:6.7.1 Gross Defects/Mechanical DamageCoatings shallbe free of visible mechanical damage and similar gross defectswhen viewed at up to 4 magnification. For some applications,this requirement ma
49、y be relaxed to allow for a small number ofsuch defects (per unit area), especially if they are outside of oron the periphery of significant surfaces (also see 6.7.2), asallowed by the purchaser.6.7.2 PorosityAlmost all as-plated electrodeposits containsome porosity. The amount of porosity in the coating that maybe tolerable depends on the severity of the environment that thearticle is likely to encounter during service or storage. If thepores are few in number, or away from significant surfaces,their presence can often be tolerated. Suc
