ASTM B520-93(2002)e1
(Specification)Standard Specification for Tin-Coated, Copper-Clad Steel Wire for Electronic Application
Standard Specification for Tin-Coated, Copper-Clad Steel Wire for Electronic Application
SCOPE
1.1 This specification covers tin-coated copper-clad steel wire for electronic application.
1.2 Four classes of tin-coated copper-clad steel wire are covered as follows:
1.2.1 Class T30HS— Nominal 30 % conductivity, hard-drawn,
1.2.2 Class T30A—Nominal 30 % conductivity, annealed,
1.2.3 Class T40HS—Nominal 40 % conductivity, hard-drawn, and
1.2.4 Class T40A—Nominal 40 % conductivity, annealed.
1.3 The values stated in inch-pound units are to be regarded as the standard. The metric equivalents of inch-pound units may be approximate. The values given in parentheses are for information only.
1.4 The following safety hazards caveat pertains only to the test method portion, Section 6, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (Warning—Consideration should be given to toxicity and flammability when selecting solvent cleaners.)
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e1
Designation: B 520 – 93 (Reapproved 2002)
Standard Specification for
Tin-Coated, Copper-Clad Steel Wire for Electronic
Application
This standard is issued under the fixed designation B 520; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript 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.
e NOTE—A precautionary note was moved into the section text editorially October 2002.
1. Scope Used as Electrical Conductors
B 452 Specification for Copper-Clad Steel Wire for Elec-
1.1 This specification covers tin-coated copper-clad steel
tronic Application
wire for electronic application.
2.3 National Institute of Standards and Technology:
1.2 Four classes of tin-coated copper-clad steel wire are
NBS Handbook 100—Copper Wire Tables
covered as follows:
1.2.1 Class T30HS— Nominal 30 % conductivity, hard-
3. Ordering Information
drawn,
3.1 Orders for material under this specification shall include
1.2.2 Class T30A—Nominal 30 % conductivity, annealed,
the following information:
1.2.3 Class T40HS— Nominal 40 % conductivity, hard-
3.1.1 Quantity of each size.
drawn, and
3.1.2 Wire size (see 5.3 and Table 1),
1.2.4 Class T40A—Nominal 40 % conductivity, annealed.
3.1.3 Class of wire (see 1.2),
1.3 The values stated in inch-pound units are to be regarded
3.1.4 Package size and shipping (see 7.1.7 and Section 9),
as the standard. The metric equivalents of inch-pound units
packaging inspection if required (see 9.3.3),
may be approximate. The values given in parentheses are for
3.1.5 Special package marking, if required, and
information only.
3.1.6 Place of inspection (see 9.1).
1.4 The following safety hazards caveat pertains only to the
test method portion, Section 6, of this specification: This
4. Material
standard does not purport to address all of the safety concerns,
4.1 Thebasismaterialshallconsistofcopper-cladsteelwire
if any, associated with its use. It is the responsibility of the user
conforming to the product description, quality and specifica-
of this standard to establish appropriate safety and health
tion requirements of Specification B 452.
practices and determine the applicability of regulatory limita-
4.2 Thetin-coatedwireshallconsistofthebasiswirecoated
tions prior to use. (Warning—Consideration should be given
with tin. The tin used for coating shall be commercially pure
to toxicity and flammability when selecting solvent cleaners.)
(Note 1). For purposes of this specification, the tin shall be
considered“ commercially pure” if the total of other elements,
2. Referenced Documents
exclusive of copper, does not exceed 1 %. Notwithstanding the
2.1 The following documents of the issue in effect on date
previoussentence,chemicalanalysisofthetincoatingorofthe
of material purchase form a part of this specification to the
tin used for coating shall not be required under this specifica-
extent referenced herein:
tion.Adequacyofthetincoatingisassuredbythecontinuityof
2.2 ASTM Standards:
coating and adherence of coating requirements (see 5.4 and
B 193 Test Method for Resistivity of Electrical Conductor
2 5.5). The quality of the tin-coated wire shall be such that the
Materials
finished product meets the properties and requirements in this
B 258 Specification for Standard Nominal Diameters and
specification.
Cross-SectionalAreasofAWGSizesofSolidRoundWires
NOTE 1—It is necessary that the coating of the tin on the wire be
continuous. The test in the sodium polysulfide is for the purpose of
determining whether or not the wire carries a continuous envelope of pure
This specification is under the jurisdiction of ASTM Committee B01 on
tin. The thickness of the tin coating is necessarily varied. Under the same
Electrical Conductors and is the direct responsibility of Subcommittee B01.06 on
Composite Conductors.
Current edition approved Oct. 10, 2002. Published September 1993. Originally
e1 3
published as B 520 – 70. Last previous edition B 520 – 70(1988) Available from National Institute of Standards and Technology (NIST), 100
Annual Book of ASTM Standards, Vol 02.03. Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B 520 – 93 (2002)
TABLE 1 Wire Sizes TABLE 2 Resistivity, max at 20°C
Diameter Cross-Sectional Area at 20°C (68°F) Class of Nominal Diameter, in.
V·mm /m
Wire (mm)
2 2
in. mm cmil in. mm
T30HS 0.0720 (1.829) to 0.06743
0.0720 1.8129 5180 0.00407 2.63
0.0201 (0.511) incl (0.067427)
0.0641 1.6128 4110 0.00323 2.08
and under 0.0201 (0.511) to 0.07315
0.0571 1.450 3260 0.00256 1.65
0.0113 (0.287) incl (0.073148)
0.0508 1.290 2580 0.00203 1.31
T30A under 0.0113 (0.287) to 0.07642
0.0453 1.151 2050 0.00161 1.04
0.0031 (0.079) incl (0.076423)
0.0403 1.024 1620 0.00128 0.823
T40HS 0.0720 (1.829) to 0.04874
0.0359 0.912 1290 0.00101 0.653
0.0201 (0.511) incl (0.048742)
0.0320 0.813 1020 0.000804 0.519
and under 0.0201 (0.511) to 0.05162
0.0285 0.724 812 0.000638 0.412
0.0113 (0.287) incl (0.051618)
0.0253 0.643 640 0.000503 0.324
T40A under 0.0113 (0.287) to 0.05328
0.0226 0.574 511 0.000401 0.259
0.0031 (0.079) incl (0.053280)
0.0201 0.511 404 0.000317 0.205
0.0179 0.455 320 0.000252 0.162
0.0159 0.404 253 0.000199 0.128
subject is contained in NBS Handbook 100. The use of five significant
0.0142 0.361 202 0.000158 0.102
figures in expressing resistivity does not imply the need for greater
0.0126 0.320 159 0.000125 0.0804
0.0113 0.287 128 0.000100 0.0647 accuracy of measurement than that specified in Test Method B 193. The
0.0100 0.254 100 0.0000785 0.0507
use of five significant figures is required for complete reversible conver-
sion from one set of resistivity units to another.
0.0089 0.226 79.2 0.0000622 0.0401
0.0080 0.203 64.0 0.0000503 0.0324
5.3 Dimensions and Permissible Variations—The wire sizes
0.0071 0.180 50.4 0.0000396 0.0255
shall be expressed as the diameter of the wire in decimal
0.0063 0.160 39.7 0.0000312 0.0201
fractions of an inch to the nearest 0.0001 in. (0.003 mm) (Note
0.0056 0.142 31.4 0.0000246 0.0159
0.0050 0.127 25.0 0.0000196 0.0127
3). For diameters under 0.0100 in. (0.254 mm), the wire shall
not vary from the specified diameter by more than plus 0.0003
0.0045 0.114 20.2 0.0000159 0.0103
in. (0.008 mm) and minus 0.0001 in. (0.003 mm) and for
0.0040 0.102 16.0 0.0000126 0.00811
0.0035 0.089 12.2 0.00000962 0.00621 diameters of 0.0100 in. (0.254 mm) and over, the wire shall not
0.0031 0.079 9.61 0.00000755 0.00487
vary from the specified diameter by more than plus 3 % and
minus 1 %, expressed to the nearest 0.0001 in. (0.003 mm).
NOTE 3—The values of the wire diameters in Table 1 are given to the
conditions of tinning, the coating on all sizes of wire, excepting on fine
nearest 0.0001 in. (0.003 mm) and correspond to the standard sizes given
wire, is approximately the same. The coating on fine wire is in general
in Specification B 258. The use of gage numbers to specify wire sizes is
relatively heavier than that on coarse wire. It is not, therefore, correct to
notrecognizedinthisspecificationbecauseofthepossibilityofconfusion.
apply a larger number of cycles in the test on coarse wire than is applied
An excellent discussion of wire gages and related subjects is contained in
to fine wire. It is probable that one cycle of the dip test would be sufficient
“Copper Wire Tables” NBS Handbook 100.
to discover defects in tinned wire, but in order to make certain that no
partially covered spots may escape attention, provision has been made for
5.4 Continuity of Coating—The tin coating shall be con-
two cycles. It has been found that the tin coating on copper wire consists
tinuous. The continuity of coating on the wire shall be
of two parts, an envelope of pure tin on the outside, with an intermediate
determinedonrepresentativesamplestakenbeforestrandingor
layer of copper-tin alloy. This tin alloy, as well as the amount of tin
insulating.The continuity of tinning shall be determined by the
present, has an effect on the resistivity of the wire. Since the relative
hydrochloric acid-sodium polysulfide test in accordance with
amount of tin coating and alloy is greater on the small wire than it is on
the coarser wire, the resistivity of the wire increases as the size decreases. 6.2.
This also accounts for the decrease in elongation due to tinning soft wire.
5.5 Adherence of Coating—The tin coating shall be firmly
adherent to the surface of the copper-clad steel wire. The
5. General Requirements
adherence of coating on the wire shall be determined on
5.1 Tensile strength and elongation of the tin-coated wire
representative samples taken before stranding or insulating.
shall conform to the requirements of Specification B 452 for
The adherence of coating shall be determined by the wrapping
the applicable size and class of copper-clad steel wire.
and immersion test in accordance with 6.3.
5.2 Resistivity— The electrical resistivity at a temperature
5.6 Joints—Necessary joints in the wire and rods prior to
of 20°C shall not exceed the values prescribed in Table 2. See
final coating and drawing shall be made in accordance with
Note 2 for calculating electrical resistance.
good commercial practice. Joints made after coating shall not
be allowed to remain in the final product.
NOTE 2—Relationships that may be useful in connection with the
5.7 Finish—The coating shall consist of a smooth, continu-
values of electrical resistivity prescribed in this specification are shown in
2 2
Table 3. Resistivity units ⁄58 V·mm /m and 0.15328 V · g/m at 20°C are
ouslayer,firmlyadherenttothesurfaceofthecopper.Thewire
respectively the international equivalent of volume and weight resistivity
shall be bright and free from all imperfections not consistent
of annealed copper equal to 100 % conductivity. The latter term means
with good commercial practice.
that a copper wire1min length and weighing 1 g would have a resistance
of 0.15328 V. This is equivalent to a resistivity value of 875.20
6. Test Methods
V·lb/mile , which signifies the resistance of a copper wire 1 mile in length
6.1 For tensile strength, elongation, resistivity, dimensional
weighing 1 lb. It is also equivalent, for example, to 1.7241 µV/cm of
lengthofacopperbar1cm incrosssection.Acompletediscussionofthis measurement and the quality of the basis wire, the latest issue
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B 520 – 93 (2002)
TABLE 3 Equivalent Resistivity Values
Volume Resistivity Equivalents at 20°C
Conductivity
Class and Size, in. (mm) Volume Mass
at 20°C
2 2 2
% IACS V·mm /m V·c mil/ft µV·in. µV·cm V·lb/mile V·g/m
T30A and T30HS 0.0720
25.570 0.067427 40.56 2.6546 6.7427 3137.9 0.54953
(1.829) to 0.0201 (0.511)
Under 0.0201 (0.511) to
23.570 0.073148 44.00 2.8799 7.3148 3404.1 0.59616
0.0113 (0.287)
Under 0.0113 (0.287) to
22.560 0.076423 45.97 3.0088 7.6423 3556.5 0.62285
0.0031 (0.079)
T40A and T40HS 0.0720
35.372 0.048742 29.32 1.9190 4.8742 2268.3 0.39725
(1.829) to 0.0201 (0.511)
Under 0.0201 (0.511) to
33.401 0.051618 31.05 2.0322 5.1618 2402.2 0.42069
0.0113 (0.287)
Under 0.0113 (0.287) to
32.359 0.053280 32.05 2.0977 5.3280 2479.5 0.43423
0.0031 (0.079)
of Specification B 452 shall apply and the tests shall be sulfur (in excess of 250 g/L of solution) to provide complete
performed on the tin-coated wire. saturation, as shown by the presence in the solution of an
6.2 Continuity of Coating: excess of sulfur after the solution has been allowed to stand for
6.2.1 Specimens: at least 24 h. The test solution shall be made by diluting a
6.2.1.1 Length of Specimens—Test specimens shall each portion of the concentrated solution with distilled water to a
have a length of about 6 in. (150 mm). They shall be tagged or specificgravityof1.142at15.6°C(60°F).Thesodiumpolysul-
marked to correspond with the coil, spool, or reel from which fide test solution should have sufficient strength to blacken
they were cut. thoroughly a piece of clean untinned copper wire in 5 s. A
6.2.1.2 Treatment of Specimens—The specimens shall be portion of the test solution used for testing samples shall not be
thoroughly cleaned by immersion in a suitable organic solvent considered to be exhausted until it fails to blacken a piece of
such as benzene, ether, or trichloroethylene for at least 3 min, clean copper as described above.
then removed and wiped dry with a clean, soft cloth.
NOTE 4—It is important that the polysulfide solution be of proper
(Warning—See1.4.)Thespecimensthuscleanedshallbekept
composition and strength at the time of test. A solution which is not
wrapped in a clean, dry cloth until tested. That part of the
saturated with sulfur or which has been made from decomposed sodium
specimen to be immersed in the test solution shall not be sulfide crystals may give a false indication of failure. Therefore, the
requirement that the solution be tested by observing its blackening effect
handled. Care shall be taken to avoid abrasion by the cut ends.
on a bright copper wire is significant. Significant also is the requirement
6.2.2 Special Solutions:
that the solution be saturated with sulfur by allowing the solution to stand
6.2.2.1 Hydrochloric Acid Solution (sp gr 1.088)—
at least 24 h after preparation.Attention is called also to the necessity for
Commercial HCl (sp gr 1.12) shall be diluted with distilled
the use of sodium sulfide which has not deteriorated through exposure to
water to a specific gravity of 1.088 measured at 15.6°C (60°F).
air; and if exposure has occurred, the crystals should be tested for purity.
Aportion of HCl solution having a volume of 180 mLshall be
The “Standard Reagents Tests” of the American Chemical Society are
considered to be exhausted when the number of test specimens useful in this connection.
prescribed in Table 4 of a size as indicated in 6.2.3 have been
6.2.3 Procedure:
immersed in it for two cycles.
6.2.3.1 Immersion of Specimens—Immerse a length of at
6.2.2.2 Sodium Polysulfide Solution (sp gr 1.142) (Note 1
least 4 ⁄2 in. (115 mm) from each of the clean specimens, in
4)—A concentrated solution shall be made by dissolving
accordance with the following cycles, in test solutions main-
sodium sulfide cp crystals in distilled water until the solution is
tained at a temperature between 15.6 and 21°C (60 and 70°F):
saturated at about 21°C (70°F), and adding sufficient flowers of
(1) immerse the specimen for 1 min in the HCl solution
described in 6.2.2, wash, and wipe dry; (2) immerse the
specimen for 30 s in the sodium polysulfide solution describe
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