1、Designation: B520 12 (Reapproved 2017)Standard Specification forTin-Coated, Copper-Clad Steel Wire for ElectronicApplication1This standard is issued under the fixed designation B520; 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 () 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 c
3、overs tin-coated copper-clad steelwire for electronic application.1.2 Four classes of tin-coated copper-clad steel wire arecovered as follows:1.2.1 Class T30HSNominal 30 % conductivity, hard-drawn,1.2.2 Class T30ANominal 30 % conductivity, annealed,1.2.3 Class T40HSNominal 40 % conductivity, hard-dr
4、awn, and1.2.4 Class T40ANominal 40 % conductivity, annealed.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3.1 ExceptionThe SI val
5、ues for resistivity and volumeare to be regarded as standard.1.4 The following safety hazards caveat pertains only to thetest method portion, Section 6, of this specification: Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibilit
6、y of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use. (WarningConsideration should be givento toxicity and flammability when selecting solvent cleaners.)1.5 This international standard was developed
7、in accor-dance with internationally 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 Documents
8、2.1 The following documents of the issue in effect on dateof material purchase form a part of this specification to theextent referenced herein:2.2 ASTM Standards:2B193 Test Method for Resistivity of Electrical ConductorMaterialsB258 Specification for Nominal Diameters and Cross-SectionalAreas ofAWG
9、 Sizes of Solid Round Wires Usedas Electrical ConductorsB452 Specification for Copper-Clad Steel Wire for Elec-tronic Application2.3 National Institute of Standards and Technology:3NBS Handbook 100 Copper Wire Tables3. Ordering Information3.1 Orders for material under this specification shall includ
10、ethe following information:3.1.1 Quantity of each size.3.1.2 Wire size (see 5.3 and Table 1),3.1.3 Class of wire (see 1.2),3.1.4 Package size and shipping (see 7.1.7 and Section 9),packaging inspection if required (see 9.3.3),3.1.5 Special package marking, if required, and3.1.6 Place of inspection (
11、see 9.1).4. Material4.1 The basis material shall consist of copper-clad steel wireconforming to the product description, quality and specifica-tion requirements of Specification B452.4.2 The tin-coated wire shall consist of the basis wire coatedwith tin. The tin used for coating shall be commerciall
12、y pure(Note 1). For purposes of this specification, the tin shall beconsidered“ commercially pure” if the total of other elements,1This specification is under the jurisdiction of ASTM Committee B01 onElectrical Conductors and is the direct responsibility of Subcommittee B01.06 onBi-Metallic Conducto
13、rs.Current edition approved April 1, 2017. Published April 2017. Originallyapproved in 1970. Last previous edition approved in 2012 as B520 12. DOI:10.1520/B0520-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
14、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.Copyright ASTM International, 100 Barr Harbor Dr
15、ive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations i
16、ssued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1exclusive of copper, does not exceed 1 %. Notwithstanding theprevious sentence, chemical analysis of the tin coating or of thetin used for coating shall not be required under this specifica-tion.Adequacy of the tin co
17、ating is assured by the continuity ofcoating and adherence of coating requirements (see 5.4 and5.5). The quality of the tin-coated wire shall be such that thefinished product meets the properties and requirements in thisspecification.NOTE 1It is necessary that the coating of the tin on the wire beco
18、ntinuous. The test in the sodium polysulfide is for the purpose ofdetermining whether or not the wire carries a continuous envelope of puretin. The thickness of the tin coating is necessarily varied. Under the sameconditions of tinning, the coating on all sizes of wire, excepting on finewire, is app
19、roximately the same. The coating on fine wire is in generalrelatively heavier than that on coarse wire. It is not, therefore, correct toapply a larger number of cycles in the test on coarse wire than is appliedto fine wire. It is probable that one cycle of the dip test would be sufficientto discover
20、 defects in tinned wire, but in order to make certain that nopartially covered spots may escape attention, provision has been made fortwo cycles. It has been found that the tin coating on copper wire consistsof two parts, an envelope of pure tin on the outside, with an intermediatelayer of copper-ti
21、n alloy. This tin alloy, as well as the amount of tinpresent, has an effect on the resistivity of the wire. Since the relativeamount of tin coating and alloy is greater on the small wire than it is onthe coarser wire, the resistivity of the wire increases as the size decreases.This also accounts for
22、 the decrease in elongation due to tinning soft wire.5. General Requirements5.1 Tensile strength and elongation of the tin-coated wireshall conform to the requirements of Specification B452 for theapplicable size and class of copper-clad steel wire.5.2 ResistivityThe electrical resistivity at a temp
23、erature of20C shall not exceed the values prescribed in Table 2. SeeNote 2 for calculating electrical resistance.NOTE 2Relationships that may be useful in connection with the valuesof electrical resistivity prescribed in this specification are shown in Table3. Resistivity units158 mm2/m and 0.15328
24、g/m2at 20C arerespectively the international equivalent of volume and weight resistivityof annealed copper equal to 100 % conductivity. The latter term meansthat a copper wire1minlength and weighing 1 g would have a resistanceof 0.15328 . This is equivalent to a resistivity value of 875.20lb/mile2,
25、which signifies the resistance of a copper wire 1 mile in lengthweighing 1 lb. It is also equivalent, for example, to 1.7241 /cm oflength of a copper bar 1 cm2in cross section.Acomplete discussion of thissubject is contained in NBS Handbook 100. The use of five significantfigures in expressing resis
26、tivity does not imply the need for greateraccuracy of measurement than that specified in Test Method B193. Theuse of five significant figures is required for complete reversible conver-sion from one set of resistivity units to another.5.3 Dimensions and Permissible VariationsThe wire sizesshall be e
27、xpressed as the diameter of the wire in decimalfractions of an inch to the nearest 0.0001 in. (0.003 mm) (Note3). For diameters under 0.0100 in. (0.254 mm), the wire shallnot vary from the specified diameter by more than plus 0.0003in. (0.008 mm) and minus 0.0001 in. (0.003 mm) and fordiameters of 0
28、.0100 in. (0.254 mm) and over, the wire shall notvary from the specified diameter by more than plus 3 % andminus 1 %, expressed to the nearest 0.0001 in. (0.003 mm).NOTE 3The values of the wire diameters in Table 1 are given to thenearest 0.0001 in. (0.003 mm) and correspond to the standard sizes gi
29、venin Specification B258. The use of gage numbers to specify wire sizes is notrecognized in this specification because of the possibility of confusion.Anexcellent discussion of wire gages and related subjects is contained in“Copper Wire Tables” NBS Handbook 100.5.4 Continuity of CoatingThe tin coati
30、ng shall be continu-ous. The continuity of coating on the wire shall be determinedon representative samples taken before stranding or insulating.The continuity of tinning shall be determined by the hydro-chloric acid-sodium polysulfide test in accordance with 6.2.5.5 Adherence of CoatingThe tin coat
31、ing shall be firmlyadherent to the surface of the copper-clad steel wire. Theadherence of coating on the wire shall be determined onrepresentative samples taken before stranding or insulating.The adherence of coating shall be determined by the wrappingand immersion test in accordance with 6.3.TABLE
32、1 Wire SizesDiameter Cross-Sectional Area at 20C (68F)in. mm cmil in.2mm20.0720 1.8129 5180 0.00407 2.630.0641 1.6128 4110 0.00323 2.080.0571 1.450 3260 0.00256 1.650.0508 1.290 2580 0.00203 1.310.0453 1.151 2050 0.00161 1.040.0403 1.024 1620 0.00128 0.8230.0359 0.912 1290 0.00101 0.6530.0320 0.813
33、1020 0.000804 0.5190.0285 0.724 812 0.000638 0.4120.0253 0.643 640 0.000503 0.3240.0226 0.574 511 0.000401 0.2590.0201 0.511 404 0.000317 0.2050.0179 0.455 320 0.000252 0.1620.0159 0.404 253 0.000199 0.1280.0142 0.361 202 0.000158 0.1020.0126 0.320 159 0.000125 0.08040.0113 0.287 128 0.000100 0.0647
34、0.0100 0.254 100 0.0000785 0.05070.0089 0.226 79.2 0.0000622 0.04010.0080 0.203 64.0 0.0000503 0.03240.0071 0.180 50.4 0.0000396 0.02550.0063 0.160 39.7 0.0000312 0.02010.0056 0.142 31.4 0.0000246 0.01590.0050 0.127 25.0 0.0000196 0.01270.0045 0.114 20.2 0.0000159 0.01030.0040 0.102 16.0 0.0000126 0
35、.008110.0035 0.089 12.2 0.00000962 0.006210.0031 0.079 9.61 0.00000755 0.00487TABLE 2 Resistivity, max at 20CClass of WireNominal Diameter, in.(mm)mm2/mT30HS 0.0720 (1.829) to 0.067430.0201 (0.511) incl (0.067427)and under 0.0201 (0.511) to 0.073150.0113 (0.287) incl (0.073148)T30A under 0.0113 (0.2
36、87) to 0.076420.0031 (0.079) incl (0.076423)T40HS 0.0720 (1.829) to 0.048740.0201 (0.511) incl (0.048742)and under 0.0201 (0.511) to 0.051620.0113 (0.287) incl (0.051618)T40A under 0.0113 (0.287) to 0.053280.0031 (0.079) incl (0.053280)B520 12 (2017)25.6 JointsNecessary joints in the wire and rods p
37、rior tofinal coating and drawing shall be made in accordance withgood commercial practice. Joints made after coating shall notbe allowed to remain in the final product.5.7 FinishThe coating shall consist of a smooth, continu-ous layer, firmly adherent to the surface of the copper. The wireshall be b
38、right and free from all imperfections not consistentwith good commercial practice.6. Test Methods6.1 For tensile strength, elongation, resistivity, dimensionalmeasurement and the quality of the basis wire, the latest issueof Specification B452 shall apply and the tests shall beperformed on the tin-c
39、oated wire.6.2 Continuity of Coating:6.2.1 Specimens:6.2.1.1 Length of SpecimensTest specimens shall eachhave a length of about 6 in. (150 mm). They shall be tagged ormarked to correspond with the coil, spool, or reel from whichthey were cut.6.2.1.2 Treatment of SpecimensThe specimens shall bethorou
40、ghly cleaned by immersion in a suitable organic solventfor at least 3 min, then removed and wiped dry with a clean,soft cloth. (WarningSee 1.4.) The specimens thus cleanedshall be kept wrapped in a clean, dry cloth until tested. Thatpart of the specimen to be immersed in the test solution shallnot b
41、e handled. Care shall be taken to avoid abrasion by the cutends.6.2.2 Special Solutions:6.2.2.1 Hydrochloric Acid Solution (sp gr 1.088)Commercial HCl (sp gr 1.12) shall be diluted with distilledwater to a specific gravity of 1.088 measured at 15.6C (60F).A portion of HCl solution having a volume of
42、 180 mL shall beconsidered to be exhausted when the number of test specimensprescribed in Table 4 of a size as indicated in 6.2.3 have beenimmersed in it for two cycles.6.2.2.2 Sodium Polysulfide Solution (sp gr 1.142) (Note4)A concentrated solution shall be made by dissolvingsodium sulfide cp cryst
43、als in distilled water until the solution issaturated at about 21C (70F), and adding sufficient flowers ofsulfur (in excess of 250 g/L of solution) to provide completesaturation, as shown by the presence in the solution of anexcess of sulfur after the solution has been allowed to stand forat least 2
44、4 h. The test solution shall be made by diluting aportion of the concentrated solution with distilled water to aspecific gravity of 1.142 at 15.6C (60F). The sodium poly-sulfide test solution should have sufficient strength to blackenthoroughly a piece of clean untinned copper wire in 5 s. Thetest s
45、olution used for testing samples shall be consideredexhausted if it fails to blacken a piece of clean copper asdescribed above.NOTE 4It is important that the polysulfide solution be of propercomposition and strength at the time of test. A solution which is notsaturated with sulfur or which has been
46、made from decomposed sodiumsulfide crystals may give a false indication of failure. Therefore, therequirement that the solution be tested by observing its blackening effecton a bright copper wire is significant. Significant also is the requirementthat the solution be saturated with sulfur by allowin
47、g the solution to standat least 24 h after preparation. Attention is called also to the necessity forthe use of sodium sulfide which has not deteriorated through exposure toair; and if exposure has occurred, the crystals should be tested for purity.The “Standard Reagents Tests” of the American Chemi
48、cal Society areuseful in this connection.6.2.3 Procedure:6.2.3.1 Immersion of SpecimensImmerse a length of atleast 412 in. (115 mm) from each of the clean specimens, inaccordance with the following cycles, in test solutions main-tained at a temperature between 15.6 and 21C (60 and 70F):(1) immerse t
49、he specimen for 1 min in the HCl solutiondescribed in 6.2.2, wash, and wipe dry; (2) immerse thespecimen for 30 s in the sodium polysulfide solution describedin 6.2.2, wash, and wipe dry; (3) immerse the specimen for 1TABLE 3 Equivalent Resistivity ValuesClass and Size, in. (mm)VolumeConductivityat 20C% IACSResistivity Equivalents at 20CVolume Massmm2/m c mil/ft in. cm lb/mile2g/m2T30A and T30HS 0.0720(1.829) to 0.0201 (0.511)25.570 0.067427 40.56 2.6546 6.7427 3137.9 0.54953Under 0.0201 (0.511) to0.0113 (
