ASTM B520-93(1998)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 problems, 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. Specific hazard statements are given in Explanatory Note 1.
General Information
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Standards Content (Sample)
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Designation: B 520 – 93 (Reapproved 1998)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
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.
e NOTE—Editorial changes were made throughout in March 1998.
1. Scope B 452 Specification for Copper-Clad Steel Wire for Elec-
tronic Application
1.1 This specification covers tin-coated copper-clad steel
2.3 National Institute of Standards and Technology:
wire for electronic application.
NBS Handbook 100—Copper Wire Tables
1.2 Four classes of tin-coated copper-clad steel wire are
covered as follows:
3. Ordering Information
1.2.1 Class T30HS— Nominal 30 % conductivity, hard-
3.1 Orders for material under this specification shall include
drawn,
the following information:
1.2.2 Class T30A—Nominal 30 % conductivity, annealed,
3.1.1 Quantity of each size.
1.2.3 Class T40HS— Nominal 40 % conductivity, hard-
3.1.2 Wire size (see 5.3 and Table 1),
drawn, and
3.1.3 Class of wire (see 1.2),
1.2.4 Class T40A—Nominal 40 % conductivity, annealed.
3.1.4 Package size and shipping (see section 7.8 and Section
1.3 The values stated in inch-pound units are to be regarded
9), packaging inspection if required (see 9.3.3),
as the standard. The metric equivalents of inch-pound units
3.1.5 Special package marking, if required, and
may be approximate. The values given in parentheses are for
3.1.6 Place of inspection (see 9.1).
information only.
1.4 The following safety hazards caveat pertains only to the
4. Material
test method portion, Section 6, of this specification: This
4.1 The basis material shall consist of copper-clad steel wire
standard does not purport to address all of the safety concerns,
conforming to the product description, quality and specifica-
if any, associated with its use. It is the responsibility of the user
tion requirements of Specification B 452.
of this standard to establish appropriate safety and health
4.2 The tin-coated wire shall consist of the basis wire coated
practices and determine the applicability of regulatory limita-
with tin. The tin used for coating shall be commercially pure
tions prior to use. Specific hazard statements are given in Note
(Note 2). For purposes of this specification, the tin shall be
1.
considered“ commercially pure” if the total of other elements,
NOTE 1—Precaution: Consideration should be given to toxicity and
exclusive of copper, does not exceed 1 %. Notwithstanding the
flammability when selecting solvent cleaners.
previous sentence, chemical analysis of the tin coating or of the
tin used for coating shall not be required under this specifica-
2. Referenced Documents
tion. Adequacy of the tin coating is assured by the continuity of
2.1 The following documents of the issue in effect on date
coating and adherence of coating requirements (see 5.4 and
of material purchase form a part of this specification to the
5.5). The quality of the tin-coated wire shall be such that the
extent referenced herein:
finished product meets the properties and requirements in this
2.2 ASTM Standards:
specification.
B 193 Test Method for Resistivity of Electrical Conductor
NOTE 2—It is necessary that the coating of the tin on the wire be
Materials
continuous. The test in the sodium polysulfide is for the purpose of
B 258 Specification for Standard Nominal Diameters and
determining whether or not the wire carries a continuous envelope of pure
Cross-Sectional Areas of AWG Sizes of Solid Round Wires
tin. The thickness of the tin coating is necessarily varied. Under the same
Used as Electrical Conductors
conditions of tinning, the coating on all sizes of wire, excepting on fine
wire, is approximately the same. The coating on fine wire is in general
relatively heavier than that on coarse wire. It is not, therefore, correct to
This specification is under the jurisdiction of ASTM Committee B-1 on
apply a larger number of cycles in the test on coarse wire than is applied
Electrical Conductors and is the direct responsibility of Subcommittee B01.06 on
Composite Conductors.
Current edition approved July 15, 1993. Published September 1993. Originally
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published as B 520 – 70. Last previous edition B 520 – 70(1988) Available from the National Institute of Standards and Technology, (NIST),
Annual Book of ASTM Standards, Vol 02.03. Gaithersburg, MD 20899.
B 520
TABLE 1 Wire Sizes
Note 3 for calculating electrical resistance.
Diameter Cross-Sectional Area at 20°C (68°F)
NOTE 3—Relationships that may be useful in connection with the
2 2
in. mm cmil in. mm
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
0.0720 1.8129 5180 0.00407 2.63
0.0641 1.6128 4110 0.00323 2.08 respectively the international equivalent of volume and weight resistivity
0.0571 1.450 3260 0.00256 1.65
of annealed copper equal to 100 % conductivity. The latter term means
0.0508 1.290 2580 0.00203 1.31
that a copper wire1min length and weighing 1 g would have a resistance
0.0453 1.151 2050 0.00161 1.04
of 0.15328 V. This is equivalent to a resistivity value of 875.20
0.0403 1.024 1620 0.00128 0.823
V·lb/mile , which signifies the resistance of a copper wire 1 mile in length
weighing 1 lb. It is also equivalent, for example, to 1.7241 μV/cm of
0.0359 0.912 1290 0.00101 0.653
0.0320 0.813 1020 0.000804 0.519 length of a copper bar 1 cm in cross section. A complete discussion of this
0.0285 0.724 812 0.000638 0.412
subject is contained in NBS Handbook 100. The use of five significant
0.0253 0.643 640 0.000503 0.324
figures in expressing resistivity does not imply the need for greater
0.0226 0.574 511 0.000401 0.259
accuracy of measurement than that specified in Test Method B 193. The
0.0201 0.511 404 0.000317 0.205
use of five significant figures is required for complete reversible conver-
sion from one set of resistivity units to another.
0.0179 0.455 320 0.000252 0.162
0.0159 0.404 253 0.000199 0.128
5.3 Dimensions and Permissible Variations—The wire sizes
0.0142 0.361 202 0.000158 0.102
shall be expressed as the diameter of the wire in decimal
0.0126 0.320 159 0.000125 0.0804
0.0113 0.287 128 0.000100 0.0647
fractions of an inch to the nearest 0.0001 in. (0.003 mm) (Note
0.0100 0.254 100 0.0000785 0.0507
4). For diameters under 0.0100 in. (0.254 mm), the wire shall
not vary from the specified diameter by more than plus 0.0003
0.0089 0.226 79.2 0.0000622 0.0401
0.0080 0.203 64.0 0.0000503 0.0324
in. (0.008 mm) and minus 0.0001 in. (0.003 mm) and for
0.0071 0.180 50.4 0.0000396 0.0255
diameters of 0.0100 in. (0.254 mm) and over, the wire shall not
0.0063 0.160 39.7 0.0000312 0.0201
0.0056 0.142 31.4 0.0000246 0.0159 vary from the specified diameter by more than plus 3 % and
0.0050 0.127 25.0 0.0000196 0.0127
minus 1 %, expressed to the nearest 0.0001 in. (0.003 mm).
0.0045 0.114 20.2 0.0000159 0.0103
NOTE 4—The values of the wire diameters in Table 1 are given to the
0.0040 0.102 16.0 0.0000126 0.00811
nearest 0.0001 in. (0.003 mm) and correspond to the standard sizes given
0.0035 0.089 12.2 0.00000962 0.00621
in Specification B 258. The use of gage numbers to specify wire sizes is
0.0031 0.079 9.61 0.00000755 0.00487
not recognized in this specification because of the possibility of confusion.
An excellent discussion of wire gages and related subjects is contained in
“Copper Wire Tables” NBS Handbook 100.
to fine wire. It is probable that one cycle of the dip test would be sufficient
to discover defects in tinned wire, but in order to make certain that no
5.4 Continuity of Coating—The tin coating shall be con-
partially covered spots may escape attention, provision has been made for
tinuous. The continuity of coating on the wire shall be
two cycles. It has been found that the tin coating on copper wire consists
determined on representative samples taken before stranding or
of two parts, an envelope of pure tin on the outside, with an intermediate
insulating. The continuity of tinning shall be determined by the
layer of copper-tin alloy. This tin alloy, as well as the amount of tin
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
6.2.
the coarser wire, the resistivity of the wire increases as the size decreases.
5.5 Adherence of Coating—The tin coating shall be firmly
This also accounts for the decrease in elongation due to tinning soft wire.
adherent to the surface of the copper-clad steel wire. The
adherence of coating on the wire shall be determined on
5. General Requirements
representative samples taken before stranding or insulating.
5.1 Tensile strength and elongation of the tin-coated wire
The adherence of coating shall be determined by the wrapping
shall conform to the requirements of Specification B 452 for
and immersion test in accordance with 6.3.
the applicable size and class of copper-clad steel wire.
5.6 Joints—Necessary joints in the wire and rods prior to
5.2 Resistivity— The electrical resistivity at a temperature
final coating and drawing shall be made in accordance with
of 20°C shall not exceed the values prescribed in Table 2. See
good commercial practice. Joints made after coating shall not
be allowed to remain in the final product.
TABLE 2 Resistivity, max at 20°C
5.7 Finish—The coating shall consist of a smooth, continu-
Class of Nominal Diameter, in.
V·mm /m ous layer, firmly adherent to the surface of the copper. The wire
Wire (mm)
shall be bright and free from all imperfections not consistent
T30HS 0.0720 (1.829) to 0.06743
with good commercial practice.
0.0201 (0.511) incl (0.067427)
and under 0.0201 (0.511) to 0.07315
6. Test Methods
0.0113 (0.287) incl (0.073148)
T30A under 0.0113 (0.287) to 0.07642
6.1 For tensile strength, elongation, resistivity, dimensional
0.0031 (0.079) incl (0.076423)
measurement and the quality of the basis wire, the latest issue
T40HS 0.0720 (1.829) to 0.04874
of Specification B 452 shall apply and the tests shall be
0.0201 (0.511) incl (0.048742)
performed on the tin-coated wire.
and under 0.0201 (0.511) to 0.05162
6.2 Continuity of Coating:
0.0113 (0.287) incl (0.051618)
T40A under 0.0113 (0.287) to 0.05328
6.2.1 Specimens:
0.0031 (0.079) incl (0.053280)
6.2.1.1 Length of Specimens—Test specimens shall each
B 520
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)
have a length of about 6 in. (150 mm). They shall be tagged or fide test solution should have sufficient strength to blacken
marked to correspond with the coil, spool, or reel from which thoroughly a piece of clean untinned copper wire in 5 s. A
they were cut. portion of the test solution used for testing samples shall not be
6.2.1.2 Treatment of Specimens—The specimens shall be considered to be exhausted until it fails to blacken a piece of
thoroughly cleaned by immersion in a suitable organic solvent clean copper as described above.
such as benzene, ether, or trichloroethylene for at least 3 min,
NOTE 5—It is important that the polysulfide solution be of proper
then removed and wiped dry with a clean, soft cloth.
composition and strength at the time of test. A solution which is not
(Precaution—See Note 1.) The specimens thus cleaned shall
saturated with sulfur or which has been made from decomposed sodium
be kept wrapped in a clean, dry cloth until tested. That part of
sulfide crystals may give a false indication of failure. Therefore, the
the specimen to be immersed in the test solution shall not be
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
that the solution be saturated with sulfur by allowing the solution to stand
6.2.2 Special Solutions:
at least 24 h after preparation. Attention is called also to the necessity for
6.2.2.1 Hydrochloric Acid Solution (sp gr 1.088)—
the use of sodium sulfide which has not deteriorated through exposure to
Commercial HCl (sp gr 1.12) shall be diluted with distilled
air; and if exposure has occurred, the crystals should be tested for purity.
water to a specific gravity of 1.088 measured at 15.6°C (60°F).
The “Standard Reagents Tests” of the American Chemical Society are
A portion of HCl solution having a volume of 180 mL shall be
useful in this connection.
considered to be exhausted when the number of test specimens
6.2.3 Procedure:
prescribed in Table 4 of a size as indicated in 6.2.3 have been
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 least 4 ⁄2in. (115 mm) from each of the clean specimens, in
5)—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
sulfur (in excess of 250 g/L of solution) to provide complete described in 6.2.2, wash, and wipe dry; (2) immerse the
saturation, as shown by the presence in the solution of an specimen for 30 s in the sodium polysulfide solution described
excess of sulfur after the solution has been allowed to stand for in 6.2.2, wash, and wipe dry; ( 3) immerse the specimen for 1
at least 24 h. The test solution shall be made by diluting a
min in the HCl solution, wash, and wipe dry; (4) immerse the
portion of the concentrated solution with distilled water to a specimen for 30 s in the sodium polysulfide soluti
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