ASTM B501-99
(Specification)Standard Specification for Silver-Coated, Copper-Clad Steel Wire for Electronic Application
Standard Specification for Silver-Coated, Copper-Clad Steel Wire for Electronic Application
SCOPE
1.1 This specification covers silver-coated, round, copper-clad steel wire for electronic application.
1.2 Silver coatings in mass percentages of the total mass of the coated wire are as follows: 1.25, 2.5, 4.0, 6.1, and 8.0.
1.2.1 Silver-coated wire having different minimum percentage of silver by mass may be obtained by mutual agreement between the manufacturer and the purchaser. For information purposes, the thickness of coating in microinches provided by the mass percentages listed in 1.2 is shown in Table 1.
1.3 Four classes of copper-clad steel wire are covered as follows: Class 30HS nominal 30% conductivity hard-drawn, Class 30A nominal 30% conductivity annealed, Class 40HS nominal 40% conductivity hard-drawn, and Class 40A nominal 40% conductivity annealed.
1.4 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only except for resistivity, where the SI units are to be regarded as the standard.
1.5 The following safety hazards caveat pertains to the test method described in 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. See Explanatory Note 1.
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Designation: B 501 – 99
Standard Specification for
Silver-Coated, Copper-Clad Steel Wire for Electronic
Application
This standard is issued under the fixed designation B 501; 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.
1. Scope B 193 Test Method for Resistivity of Electrical Conductor
Materials
1.1 This specification covers silver-coated, round, copper-
B 258 Specification for Standard Nominal Diameters and
clad steel wire for electronic application.
Cross–Sectional Areas of AWG Sizes of Solid Round
1.2 Silver coatings in mass percentages of the total mass of
Wires Used as Electrical Conductors
the coated wire are as follows: 1.25, 2.5, 4.0, 6.1, and 8.0.
B 452 Specification for Copper–Clad Steel Wire for Elec-
1.2.1 Silver-coated wire having different minimum percent-
tronic Application
age of silver by mass may be obtained by mutual agreement
E 50 Practices for Apparatus, Reagents, and Safety Precau-
between the manufacturer and the purchaser. For information
tions for Chemical Analysis of Metals
purposes, the thickness of coating in microinches provided by
the mass percentages listed in 1.2 is shown in Table 1.
3. Terminology
1.3 Four classes of copper-clad steel wire are covered as
3.1 Definitions of Terms Specific to This Standard:
follows: Class 30HS nominal 30 % conductivity hard-drawn,
3.1.1 lot—any amount of wire of one class and size pre-
Class 30A nominal 30 % conductivity annealed, Class 40HS
sented for acceptance at one time, such amount, however, not
nominal 40 % conductivity hard-drawn, and Class 40A nomi-
to exceed 10 000 lb (4500 kg) (Note 2).
nal 40 % conductivity annealed.
3.1.2 sample—a quantity of production units (coils, reels,
1.4 The values stated in inch-pound units are to be regarded
etc.) selected at random from the lot for the purpose of
as the standard. The values given in parentheses are for
determining conformance of the lot to the requirements of this
information only except for resistivity, where the SI units are to
specification.
be regarded as the standard.
3.1.3 specimen—a length of wire removed for test purposes
1.5 The following safety hazards caveat pertains to the test
from any individual production unit of the sample.
method described in this specification. This standard does not
purport to address all of the safety problems, if any, associated
NOTE 2—A lot should comprise material taken from a product regularly
with its use. It is the responsibility of the user of this standard meeting the requirements of this specification. Inspection of individual
lots of less than 500 lb (250 kg) of wire cannot be justified economically.
to establish appropriate safety and health practices and
For small lots of 500 lb (250 kg) or less, the purchaser may agree to the
determine the applicability of regulatory limitations prior to
manufacturer’s regular inspection of the product as a whole as evidence of
use. (See Note 1).
acceptability of such small lots.
NOTE 1—Caution: Consideration should be given to toxicity and
4. Ordering Information
flammability when selecting solvent cleaners.
4.1 Orders for material under this specification shall include
2. Referenced Documents
the following information:
2.1 The following documents of the issue in effect on date
4.1.1 Quantity of each size,
of material purchase form a part of this specification to the
4.1.2 Wire size (see 7.1 and Table 1),
extent referenced herein:
4.1.3 Class of basis wire (see 1.3),
2.2 ASTM Standards:
4.1.4 Mass percentage of coating (see 1.2 and Table 1),
4.1.5 Package size (see Section 12),
4.1.6 Special packaging marking, if required, and
This specification is under the jurisdiction of ASTM Committee B-1 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.06 on
Composite Conductors.
Current edition approved April 10, 1999. Published June 1999. Originally Annual Book of ASTM Standards, Vol 02.03.
published as B 509 – 69. Last previous edition B 509 – 93. Annual Book of ASTM Standards, Vol 03.05.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 501
TABLE 1 Silver Mass Percent and Thickness of Coating
Thickness of Silver, μin.
Diameter Cross-Sectional Area at 20°C
(for information only)
1.25 2.5 4.0 6.1 8.0
2 2
in. mm cmil in. mm
% % % % %
0.0720 1.829 5 180 0.00407 2.63 176 352 569 876 1 158
0.0641 1.628 4 110 0.00323 2.08 156 313 507 779 1 031
0.0571 1.450 3 260 0.00256 1.65 139 279 451 694 918
0.0508 1.290 2 580 0.00203 1.31 124 248 401 618 817
0.0453 1.151 2 050 0.00161 1.04 111 222 358 551 728
0.0403 1.024 1 620 0.00128 0.823 98 197 318 490 648
0.0359 0.912 1 290 0.00101 0.653 88 176 284 437 577
0.0320 0.813 1 020 0.000804 0.519 78 156 253 389 515
0.0285 0.724 812 0.000638 0.412 70 139 225 347 458
0.0253 0.643 640 0.000503 0.324 62 124 200 308 407
0.0226 0.574 511 0.000401 0.259 55 111 179 275 363
0.0201 0.511 404 0.000317 0.205 49 98 159 244 323
0.0179 0.455 320 0.000252 0.162 44 88 141 218 288
0.0159 0.404 253 0.000199 0.128 39 78 126 193 256
0.0142 0.361 202 0.000158 0.102 35 69 112 173 228
0.0126 0.320 159 0.000125 0.0804 31 62 100 153 203
0.0113 0.287 128 0.000100 0.0647 28 55 89 137 182
0.0100 0.254 100 0.0000785 0.0507 24 49 79 122 161
0.0089 0.226 79.2 0.0000622 0.0401 22 44 70 108 143
0.0080 0.203 64.0 0.0000503 0.0324 39 63 97 129
0.0071 0.180 50.4 0.0000396 0.0255 35 56 86 114
0.0063 0.160 39.7 0.0000312 0.0201 31 50 77 101
0.0056 0.142 31.4 0.0000246 0.0159 26 44 68 90
0.0050 0.127 25.0 0.0000196 0.0127 24 40 61 80
0.0045 0.114 20.2 0.0000159 0.0103 22 36 55 72
0.0040 0.102 16.0 0.0000126 0.00811 32 49 64
0.0035 0.089 12.2 0.00000962 0.00621 28 43 56
0.0031 0.079 9.61 0.00000755 0.00487 24 38 50
TABLE 2 Resistivity
4.1.7 Place of inspection (see 9.1).
Resistivity, max at 20°C
Class of Wire V·mm /m
30HS and 30A 0.05862 (0.0586160)
5. Materials and Manufacture
40HS and 40A 0.04397 (0.043970)
5.1 The basis material shall consist of copper-clad steel wire
conforming to the product description, quality and specifica-
tion requirements of Specification B 452.
5.2 The silver-coated wire shall consist of the basis wire 6.3 Continuity of Coating—The coating shall be continu-
coated with silver. The quality of the silver-coated wire shall be ous. The continuity of the coating shall be determined on
such that the finished product meets the properties and require-
representative samples taken before stranding or insulating and
ments in this specification (Note 3). shall be determined by the sodium polysulfide test, in accor-
dance with 10.2.3.1. Wire whose coating mass corresponds to
NOTE 3—Silver coatings on copper-clad steel provide for:
a thickness less than 0.00005 in. (50 μin.) shall not be subject
(a) A barrier between the copper and insulation whose curing tempera-
to this test.
ture in the process of fabricating is too high for the use of tin-coated wires.
(b) A low contact resistance between the strands of outer conductors of 6.4 Mass of Coating— The mass of coating expressed in
coaxial conductors used in high-frequency circuits.
percent of the total mass of the wire shall be not less than the
(c) A low radio-frequency resistance of conductors used in high-
percentage specified and referred to in this specification or the
frequency circuits (skin effect).
percentage as agreed on between the manufacturer and pur-
(d) Good solderability for high-temperature hook-up wires which
chaser at the time of the placing of the order. For ease of
prohibit the use of tin-coated wires due to high curing temperatures used
comparison, the thickness of coating for various percentages
in fabricating the finished wire.
has been included in Table 1.
6. General Requirements
6.5 Joints—Necessary joints in the wire and rods prior to
final coating and drawing shall be made in accordance with
6.1 Tensile strength and elongation of the silver-coated wire
good commercial practice. Joints made after coating shall not
shall conform to the requirements of Specification B 452 for
be allowed to remain in the final product.
the applicable size and class of copper-clad steel wire.
6.2 Resistivity— The electrical resistivity at a temperature
NOTE 4—Relationships which may be useful in connection with the
of 20°C shall not exceed the values prescribed in Table 2. See
values of electrical resistivity prescribed in this specification are shown in
Note 4 for calculating electrical resistance. Table 2. Resistivity units are based on the International Annealed Copper
B 501
Standard (IACS) adopted by IEC in 1913, which is ⁄58 V·mm /m at 20°C
of eight production units. From each unit, one test specimen of
for 100 % conductivity. The values of 0.017241 V·mm /m and the value
sufficient length shall be removed for the performance of the
of 0.15328 V·g/m at 20°C are respectively the international equivalent of
required test.
volume and mass resistivity of annealed copper equal to 100 % conduc-
9.3 For dimensional measurements and surface finish, the
tivity. The latter term means that a copper wire1min length and mass of
samples shall consist of a quantity of production units shown in
1 g would have a resistance of 0.15328 V. This is equivalent to a
resistivity value of 875.20 V·lb/mile , which signifies the resistance of a Table 3 under the heading “First Sample.”
copper wire 1 mile in length with mass of 1 lb. It is also equivalent, for
9.4 For packaging inspection (when specified by the pur-
example, to 1.7241 μV/cm of length of a copper bar 1 cm in cross section.
chaser at the time of placing the order), the sample shall consist
A complete discussion of this subject is contained in NBS Handbook 100
of a quantity of production units shown in Table 4.
of the National Institute of Standards and Technology. The use of five
significant figures in expressing resistivity does not imply the need for
NOTE 6—Cumulative results secured on the product of a single manu-
greater accuracy of measurement than that specified in Test Method
facturer indicating continued conformance to the criteria, are necessary to
B 193. The use of five significant figures is required for complete
ensure an overall product meeting the requirements of this specification.
reversible conversion from one set of resistivity units to another.
The sample size and conformance criteria given for the various charac-
teristics are applicable only to lots produced under these conditions.
7. Dimensions and Permissible Variations
7.1 The wire sizes shall be expressed as the diameter of the
10. Test Methods
wire in decimal fractions of an inch to the nearest 0.0001 in.
10.1 For tensile strength, elongation, resistivity, dimen-
(0.003 mm) (Note 5). For diameters under 0.0100 in. (0.254
sional measurement and the quality of the basis wire, the latest
mm), the wire shall not vary from the specified diameter by
issue of Specification B 452 shall apply and the tests shall be
more than 60.0001 in. (0.003 mm) and for diameters of 0.0100
performed on the silver-coated wire (Note 7).
in. (0.254 mm) and over, the wire shall not vary from the
specified diameter by more than 61 %, expressed to the NOTE 7—It is known that the rate of loading during tension testing
affects the performance of the sample to a greater or lesser extent
nearest 0.0001 in. (0.003 mm).
depending upon many factors. In general, tested values of tensile strength
NOTE 5—The values of the wire diameters in Table 1 are given to the
are increased and tested values of elongation are reduced with increase of
nearest 0.0001 in. and correspond to the standard sizes given in Specifi-
speed of the moving head of the testing machine. In the case of tests on
cation B 258. The use of gage numbers to specify wires is not recognized
soft or annealed wire, however, the effects of speed of testing are not
in this specification because of the possibility of confusion. An excellent
pronounced. Tests of soft wire made at speeds of moving head which
discussion of wire gages and related subjects is contained in NBS
under no-load conditions are not greater than 12 in./min (300 mm/min) do
Handbook 100 of the National Institute of Standards and Technology.
not alter the final results of tensile strength and elongation determinations
to any practical extent. In the case of hard-drawn wire, these effects are
8. Workmanship, Finish, and Appearance
pronounced when the speed of the moving head is excessive. It is
suggested that tests be made at speeds of moving head which, under
8.1 The coating shall consist of a smooth, continuous layer,
no-load conditions, are not greater than 3 in./min (76 mm/min), but in no
firmly adherent to the surface of the copper. The wire shall be
case at a speed greater than that at which correct readings can be made.
bright and free from all imperfections not consistent with good
commercial practice. 10.2 Continuity of Silver Coating:
10.2.1 Specimens:
9. Sampling
10.2.1.1 Length of Specimens—Test specimens shall each
9.1 The number of production units in a sample (Note 6)
have a length of about 6 in. (150 mm). They shall be tagged or
shall be as follows:
marked to correspond with the coil, spool, or reel from which
9.2 For elongation, resistivity, and mass of coating determi-
they were cut.
nations, the sample shall consist of four production units. For
10.2.1.2 Treatment of Specimens—The specimens shall be
continuity of coating determinations, the sample shall consist
thoroughly cleaned by immersion in a suitable organic solvent
such as benzene, ether, or trichlorethylene for at least 3 min;
then removed and wiped dry with a clean, soft cloth. The
specimens thus cleaned shall be kept wrapped in a clean, dry
Available from the National Institute of Standards and Technology, (NIST),
cloth until tested. That part of the specimen to be immersed in
Gaithersburg, MD 20899.
TABLE 3 Sampling for Dimensional Measurements
First Sample Second Sample
No. of Allowable No. No. of Allowable No.
No. of Units in Lot
Units in of Defects in Units in n + n of Defects in
1 2
Sample n Sample c Sample n both Samples, c
1 1 2 2
1 to 14, incl all 0 . . 0
15 to 50, incl 14 0 . . 0
51 to 100, incl 19 0 23 42 1
101 to 200, incl 24 0 46 70 2
201 to 400, incl 29 0 76 105 3
401 to 800, incl 33 0 112 145 4
Over 800 34 0 116 150 4
B 501
TABLE 4 Sampling for Surface Finish and Packaging Inspection
scribed in 10.2
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