1、Designation: B 520 93 (Reapproved 2007)Standard Specification forTin-Coated, Copper-Clad Steel Wire for ElectronicApplication1This standard is issued under the fixed designation B 520; 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 (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. Scope1.1 This specification cov
3、ers 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-draw
4、n, and1.2.4 Class T40ANominal 40 % conductivity, annealed.1.3 The values stated in inch-pound units are to be regardedas the standard. The metric equivalents of inch-pound unitsmay be approximate. The values given in parentheses are forinformation only.1.4 The following safety hazards caveat pertain
5、s 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 responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicab
6、ility of regulatory limita-tions prior to use. (WarningConsideration should be givento toxicity and flammability when selecting solvent cleaners.)2. Referenced Documents2.1 The following documents of the issue in effect on dateof material purchase form a part of this specification to theextent refer
7、enced herein:2.2 ASTM Standards:2B 193 Test Method for Resistivity of Electrical ConductorMaterialsB 258 Specification for Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Usedas Electrical ConductorsB 452 Specification for Copper-Clad Steel Wire for Elec-tronic Applicat
8、ion2.3 National Institute of Standards and Technology:3NBS Handbook 100 Copper Wire Tables3. Ordering Information3.1 Orders for material under this specification shall includethe 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
9、.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 (see 9.1).4. Material4.1 The basis material shall consist of copper-clad steel wireconforming to the product description, quali
10、ty and specifica-tion requirements of Specification B 452.4.2 The tin-coated wire shall consist of the basis wire coatedwith tin. The tin used for coating shall be commercially pure(Note 1). For purposes of this specification, the tin shall beconsidered“ commercially pure” if the total of other elem
11、ents,exclusive 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 coating is assured by the continuity ofcoating and adherence of coating requirem
12、ents (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 becontinuous. The test in the sodium polysulfide is for the purpose ofdetermining
13、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 approximately the same. The coating on fine wire is in general1This specification
14、 is under the jurisdiction of ASTM Committee B01 onElectrical Conductors and is the direct responsibility of Subcommittee B01.06 onComposite Conductors.Current edition approved Oct. 1, 2007. Published October 2007. Originallyapproved in 1970. Last previous edition approved in 2002 as B 520 70 (2002)
15、e12For referenced ASTM standards, visit 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.3Available from National Institute of Standards and Technol
16、ogy (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.relatively heavier than that on coarse wire. It is not, therefore, correct toapply a larger number
17、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 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
18、found that the tin coating on copper wire consistsof two parts, an envelope of pure tin on the outside, with an intermediatelayer of copper-tin 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
19、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 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 req
20、uirements of Specification B 452 forthe applicable size and class of copper-clad steel wire.5.2 ResistivityThe electrical resistivity at a temperature of20C shall not exceed the values prescribed in Table 2. SeeNote 2 for calculating electrical resistance.NOTE 2Relationships that may be useful in co
21、nnection with thevalues of electrical resistivity prescribed in this specification are shown inTable 3. Resistivity units158 V mm2/m and 0.15328 V g/m2at 20C arerespectively the international equivalent of volume and weight resistivityof annealed copper equal to 100 % conductivity. The latter term m
22、eansthat a copper wire1minlength and weighing 1 g would have a resistanceof 0.15328 V. This is equivalent to a resistivity value of 875.20Vlb/mile2, which signifies the resistance of a copper wire 1 mile in lengthweighing 1 lb. It is also equivalent, for example, to 1.7241 V/cm oflength of a copper
23、bar 1 cm2in cross section.Acomplete discussion of thissubject is contained in NBS Handbook 100. The use of five significantfigures in expressing resistivity does not imply the need for greateraccuracy of measurement than that specified in Test Method B 193. Theuse of five significant figures is requ
24、ired for complete reversible conver-sion from one set of resistivity units to another.5.3 Dimensions and Permissible VariationsThe wire sizesshall be expressed 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. (0.2
25、54 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 0.0100 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
26、 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 givenin Specification B 258. The use of gage numbers to specify wire sizes isnot recognized in this specification because of the possibility of confusi
27、on.An excellent discussion of wire gages and related subjects is contained in“Copper Wire Tables” NBS Handbook 100.5.4 Continuity of CoatingThe tin coating shall be con-tinuous. The continuity of coating on the wire shall bedetermined on representative samples taken before stranding orinsulating. Th
28、e continuity of tinning shall be determined by thehydrochloric acid-sodium polysulfide test in accordance with6.2.5.5 Adherence of CoatingThe tin coating shall be firmlyadherent to the surface of the copper-clad steel wire. Theadherence of coating on the wire shall be determined onrepresentative sam
29、ples taken before stranding or insulating.The adherence of coating shall be determined by the wrappingand immersion test in accordance with 6.3.5.6 JointsNecessary joints in the wire and rods prior tofinal coating and drawing shall be made in accordance withgood commercial practice. Joints made afte
30、r 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 bright and free from all imperfections not consistentwith good commercial practice.6. Test Methods6.1 For te
31、nsile strength, elongation, resistivity, dimensionalmeasurement and the quality of the basis wire, the latest issueof Specification B 452 shall apply and the tests shall beperformed on the tin-coated wire.TABLE 1 Wire SizesDiameter Cross-Sectional Area at 20C (68F)in. mm cmil in.2mm20.0720 1.8129 51
32、80 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 1020 0.000804 0.5190.0285 0.724 812 0.000638 0.4120.0253 0.643 640 0.000503 0.3240.0226 0
33、.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 0.06470.0100 0.254 100 0.0000785 0.05070.0089 0.226 79.2 0.0000622 0.04010.0080 0.203 64.0 0.00
34、00503 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 0.008110.0035 0.089 12.2 0.00000962 0.006210.0031 0.079 9.61 0.00000755 0.00487TABLE 2 Res
35、istivity, max at 20CClass ofWireNominal Diameter, in.(mm)Vmm2/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 (0.287) to 0.076420.0031 (0.079) incl (0.076423)T40HS 0.0720 (1.829) to 0.048740.0201 (0.511)
36、 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)B 520 93 (2007)26.2 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
37、 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 bethoroughly cleaned by immersion in a suitable organic solventsuch as benzene, ether, or trichloroethylene for at least 3 min,then removed and wiped dry wi
38、th a clean, soft cloth.(WarningSee 1.4.) The specimens thus cleaned shall be keptwrapped in a clean, dry cloth until tested. That part of thespecimen to be immersed in the test solution shall not behandled. Care shall be taken to avoid abrasion by the cut ends.6.2.2 Special Solutions:6.2.2.1 Hydroch
39、loric 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 180 mL shall beconsidered to be exhausted when the number of test specimensprescribed in Table 4 of a
40、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 crystals in distilled water until the solution issaturated at about 21C (70F), and adding sufficient flowers
41、 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 24 h. The test solution shall be made by diluting aportion of the concentrated solution with distilled w
42、ater to aspecific gravity of 1.142 at 15.6C (60F). The sodium polysul-fide test solution should have sufficient strength to blackenthoroughly a piece of clean untinned copper wire in 5 s. Aportion of the test solution used for testing samples shall not beconsidered to be exhausted until it fails to
43、blacken a piece ofclean copper as described 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 made from decomposed sodiumsulfide crystals may give a false indication of fa
44、ilure. 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 allowing the solution to standat least 24 h after preparation. Attention is called a
45、lso 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 Chemical Society areuseful in this connection.6.2.3 Procedure:6.2.3.1 Immersion of
46、 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 the specimen for 1 min in the HCl solutiondescribed in 6.2.2, wash, and wipe d
47、ry; (2) immerse thespecimen for 30 s in the sodium polysulfide solution describedin 6.2.2, wash, and wipe dry; (3) immerse the specimen for 1min in the HCl solution, wash, and wipe dry; (4) immerse thespecimen for 30 s in the sodium polysulfide solution, wash, andwipe dry.6.2.3.2 Washing SpecimensAf
48、ter each immersion, imme-diately wash the specimens thoroughly in clean water and wipedry with a clean, soft cloth.6.2.3.3 Examination of SpecimensAfter immersion andwashing, examine the specimens with the unaided eye (normalspectacles excepted) to ascertain if copper exposed throughopenings in the
49、tin coating has been blackened by action of thesodium polysulfide. The specimens shall be considered to haveTABLE 3 Equivalent Resistivity ValuesClass and Size, in. (mm)VolumeConductivityat 20C% IACSResistivity Equivalents at 20CVolume MassVmm2/m Vc mil/ft Vin. Vcm Vlb/mile2Vg/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 (0.287)23.570 0.073148 44.00 2.8799 7.3148 3404.1 0.59616Under 0.0113 (0.287) to0.0031 (0.079)22.560 0.076423 45.97 3.0088 7.6423
