ASTM B298-12(2017)
(Specification)Standard Specification for Silver-Coated Soft or Annealed Copper Wire
Standard Specification for Silver-Coated Soft or Annealed Copper Wire
ABSTRACT
This specification covers silver-coated, soft or annealed, round copper wire, intended for use in electrical equipment. The silver-coated wires are classified according to the total weight of the coated wires, namely; Class A, B, C, D, and E. Tensile strength test, resistivity test, weight of coating, and dimensional measurements shall be performed to conform to the requirements specified.
SCOPE
1.1 This specification covers silver-coated, soft or annealed, round copper wire, intended for use in electrical equipment, as follows:
1.1.1 Class A—Wire whose silver coating is at least 1.25 % of the total weight of the coated wire.
1.1.2 Class B—Wire whose silver coating is at least 2.50 % of the total weight of the coated wire.
1.1.3 Class C—Wire whose silver coating is at least 4.00 % of the total weight of the coated wire.
1.1.4 Class D—Wire whose silver coating is at least 6.10 % of the total weight of the coated wire.
1.1.5 Class E—Wire whose silver coating is at least 10.00 % of the total weight of the coated wire.
1.2 Silver-coated wire having different minimum percentages of silver by weight may be obtained by mutual agreement between the manufacturer and the purchaser. For information purposes the thickness of coating in microinches provided by the percentages listed above is shown in Table 1 (Explanatory Note 1).
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3.1 Exceptions—The SI values for density, resistivity, and volume are to be regarded as standard.
1.4 The following precautionary caveat pertains only to the test method section 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. For specific precautionary statements see 8.4.1.2 and Explanatory Note 2.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:B298 −12 (Reapproved 2017)
Standard Specification for
Silver-Coated Soft or Annealed Copper Wire
This standard is issued under the fixed designation B298; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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. Scope 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 Thisspecificationcoverssilver-coated,softorannealed,
ization established in the Decision on Principles for the
round copper wire, intended for use in electrical equipment, as
Development of International Standards, Guides and Recom-
follows:
mendations issued by the World Trade Organization Technical
1.1.1 Class A—Wire whose silver coating is at least 1.25%
Barriers to Trade (TBT) Committee.
of the total weight of the coated wire.
1.1.2 Class B—Wire whose silver coating is at least 2.50%
2. Referenced Documents
of the total weight of the coated wire.
1.1.3 Class C—Wire whose silver coating is at least 4.00% 2.1 The following documents of the issue in effect at the
of the total weight of the coated wire. time of reference form a part of this specification to the extent
1.1.4 Class D—Wire whose silver coating is at least 6.10% referenced herein:
of the total weight of the coated wire. 2
2.2 ASTM Standards:
1.1.5 Class E—Wirewhosesilvercoatingisatleast10.00%
B49Specification for Copper Rod for Electrical Purposes
of the total weight of the coated wire.
B193Test Method for Resistivity of Electrical Conductor
1.2 Silver-coated wire having different minimum percent- Materials
agesofsilverbyweightmaybeobtainedbymutualagreement B258 Specification for Nominal Diameters and Cross-
between the manufacturer and the purchaser. For information SectionalAreasofAWGSizesofSolidRoundWiresUsed
purposes the thickness of coating in microinches provided by as Electrical Conductors
the percentages listed above is shown in Table 1 (Explanatory E50Practices for Apparatus, Reagents, and Safety Consid-
Note 1). erations for Chemical Analysis of Metals, Ores, and
Related Materials
1.3 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
3. Ordering Information
conversions to SI units that are provided for information only
and are not considered standard.
3.1 Ordersformaterialunderthisspecificationshallinclude
1.3.1 Exceptions—The SI values for density, resistivity, and the following information:
volume are to be regarded as standard.
3.1.1 Quantity of each size,
1.4 The following precautionary caveat pertains only to the 3.1.2 Wire size, diameter in inches (see 5.3 and Table 1),
testmethodsectionofthisspecification: This standard does not 3.1.3 Class of coating (Section 1 and Table 1),
purport to address all of the safety concerns, if any, associated
3.1.4 Type of copper, if special (see 4.2),
with its use. It is the responsibility of the user of this standard
3.1.5 Place of inspection (see 9.1), and
to establish appropriate safety and health practices and
3.1.6 Packaging and Package Marking (Section 10).
determine the applicability of regulatory limitations prior to
3.1.7 In addition supplementary requirements shall apply
use. For specific precautionary statements see 8.4.1.2 and
onlywhenspecifiedbythepurchaserintheinquiry,contract,or
Explanatory Note 2.
purchase order for direct procurement by agencies of the U.S.
Government (see S1, S2, and S3).
This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
Conductors of Copper and Copper Alloys. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2017. Published April 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1955. Last previous edition approved in 2012 as B298–12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0298-12R17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B298−12 (2017)
TABLE 1 Tensile Requirements
Area at 20°C Thickness of Coating, µin. (For Information Only)
Elongation
Diameter,
in 10 in.,
Class A, 1.25 Class B, 2.50 Class C, 4.00 Class D, 6.10 Class E, 10.00
in.
cmils in.
min, %
% Silver % Silver % Silver % Silver % Silver
0.1285 16 510 0.01297 30 340 680 1 090 1 659 2 720
0.1144 13 090 0.01028 30 303 605 970 1 477 2 422
0.1019 10 380 0.008155 25 270 539 864 1 316 2 157
0.0907 8 230 0.00646 25 240 480 768 1 171 1 941
0.0808 6 530 0.00513 25 214 428 684 1 043 1 710
0.0720 5 180 0.00407 25 190 381 610 930 1 524
0.0641 4 110 0.00323 25 170 339 542 828 1 357
0.0571 3 260 0.00256 25 151 302 483 737 1 209
0.0508 2 580 0.00203 25 134 269 430 656 1 075
0.0453 2 050 0.00161 25 120 240 383 585 959
0.0403 1 620 0.00128 25 107 213 341 520 853
0.0359 1 290 0.00101 25 95 190 304 464 760
0.0320 1 020 0.000804 25 85 169 270 413 677
0.0285 812 0.000638 25 75 151 241 368 603
0.0253 640 0.000503 25 67 134 214 327 536
0.0226 511 0.000401 25 60 120 191 292 478
0.0201 404 0.00317 20 53 106 170 260 425
0.0179 320 0.000252 20 47 95 151 231 379
0.0159 253 0.000199 20 42 84 135 205 337
0.0142 202 0.000158 20 . 75 120 183 301
0.0126 159 0.000125 20 . 67 107 163 267
0.0113 128 0.000100 20 . 60 96 146 239
0.0100 100 0.0000785 20 . 53 85 129 212
0.0089 79.2 0.0000622 15 . 47 75 115 188
0.0080 64.0 0.0000503 15 . 42 68 103 169
0.0071 50.4 0.0000396 15 . . 60 92 150
0.0063 39.7 0.0000312 15 . . 53 81 133
0.0056 31.4 0.0000246 15 . . 47 72 119
0.0050 25.0 0.0000196 15 . . 42 65 106
0.0045 20.2 0.0000159 15 . . . 58 95
0.0040 16.0 0.0000126 15 . . . 52 85
0.0035 12.2 0.00000962 15 . . . 45 74
0.0031 9.61 0.00000755 15 . . . 40 66
0.0028 7.84 0.00000616 10 . . . . 59
0.0025 6.25 0.00000491 10 . . . . 53
0.0022 4.84 0.00000380 10 . . . . 47
0.0020 4.00 0.00000314 10 . . . . 42
4. Materials and Manufacture 5.3 Dimensions and Permissible Variations—Thewiresizes
shall be expressed as the diameter of the wire in decimal
4.1 The material shall be silver-coated copper wire (Ex-
fractions of an inch to the nearest 0.0001 in. (0.0025 mm)
planatory Note 2), of such quality and purity that the finished
(Explanatory Note 3). The coated wire shall not vary from the
product shall have the properties and characteristics prescribed
specified diameter by more than the following amounts:
in this specification.
Permissible Variations in
Nominal Diameter, in.
NOTE 1—The following specifications define copper suitable for use:
Diameter, plus and minus
Specification B49.
Under 0.0100 0.0001 in.(0.1 mil)
0.0100 or over 1 %
4.2 Copper of special qualities, forms, or types, as may be
5.4 Continuity of Coating—Thecoatingshallbecontinuous.
agreed upon between the manufacturer and the purchaser, and
The continuity of the coating shall be determined on represen-
that will conform to the requirements prescribed in this
tativesamplestakenbeforestrandingorinsulatingandshallbe
specification may also be used.
determined by the sodium polysulfide test, in accordance with
5. General Requirements
8.4.Wirewhosecoatingweightcorrespondstoathicknessless
than 40µ in. (0.00004 in.) shall not be subject to this test
5.1 Tensile Properties—The silver-coated wire shall con-
(Explanatory Note 4).
form to the requirements for elongation prescribed in Table 1.
No requirements for tensile strength are specified. For wire
5.5 Weight of Coating—The weight of coating expressed in
whose nominal diameter is more than 0.001 in. (0.025 mm)
percent of the total weight of the wire shall be not less than
greater than a size listed in Table 1, but less than that of the
1.25% for Class A; 2.50% for Class B; 4.00% for Class C;
next larger size, the requirements of the next larger size shall
6.10% for Class D; and 10.00% for Class E. When coatings
apply.
other than these classes are required, the weight of the coating
5.2 Resistivity—The electrical resistivity of the coated wire shallbenotlessthanthatspecified.Foreaseofcomparison,the
at a temperature of 20°C shall not exceed 875.20 ohms·lb/ thickness of coating for these classes has been included in
mile . Table 1 (Explanatory Note 4).
B298−12 (2017)
5.6 Joints—Necessary joints in the wire and rods prior to 6.5 Weight of Coating—Theweightofcoatingofeachofthe
final plating and drawing shall be made in accordance with the four specimens shall conform to the requirements of 5.5.
bestcommercialpractice.Jointsmadeafterplatingshallnotbe Failure of more than one specimen shall constitute failure to
allowed to remain in the final product. meet the weight criteria. If only one specimen fails to meet the
weight criteria, four additional specimens from the lot shall be
5.7 Finish—The coating shall consist of a smooth continu-
tested, all of which shall conform to the weight criterion.
ouslayer,firmlyadherenttothesurfaceofthecopper.Thewire
However, any individual production unit, the specimen from
shall be bright and free from all imperfections not consistent
which failed the weight criteria, shall be rejected.
with the best commercial practice.
6.6 Packaging—Conformance to the packaging require-
6. Conformance Criteria (Explanatory Note 5)
ments specified by the purchaser shall be determined in
accordance with Table 3. The number of units in the sample
6.1 Any lot of wire, the samples of which comply with the
conformance criteria of this section, shall be considered as showing nonconformance to the requirements shall not exceed
the allowable defect number, c,in Table 3. Failure to meet this
complying with the requirements of Section 5. Individual
production units that fail to meet one or more of the require- requirement shall constitute failure to meet the packaging
mentsshallberejected.Failureofasamplegroupfromalotto conformance criterion.
meet one or more of the following criteria shall constitute
7. Density
causeforrejectionofthelot.Theconformancecriteriaforeach
7.1 For the purpose of calculating weights, cross-sections,
of the prescribed properties given in Section 5 are as follows:
etc., the density of the copper shall be taken as 8.89 g/cm
6.1.1 Elongation—Thelotshallbeconsideredconformingif
(0.32117 lb/in. ) at 20°C (Explanatory Note 6). The density of
theelongationofeachoftheselectedspecimensisnotlessthan
3 3
silver shall be taken as 10.5 g/cm (0.1 mil) (0.37933 lb/in. ).
the elongation value in Table 1.
6.2 Resistivity—The electrical resistivity of each of the four 8. Test Methods
specimens shall conform to the requirements of 5.2. Failure to
8.1 Tensile Strength and Elongation:
meet these requirements shall constitute failure to meet the
8.1.1 No test for tensile strength shall be required.
resistivity conformance criterion.
8.1.2 The elongation of wire with a nominal diameter
6.3 Dimensions—The dimensions of the first sample (Table greater than 0.0808 in. (2.052 mm) shall be determined as the
2) shall conform to the requirements of 5.3. If there are no permanent increase in length due to the breaking of the wire in
failures, the lot conforms to this requirement. If there are tension (see Explanatory Note 7). The elongation shall be
failures, but the number of these do not exceed the allowable measured between gage marks placed originally 10 in. (242
defectnumber, c (Table2),fortherespectivenumberofunits mm) apart upon the test specimen and expressed in percent of
in the sample, a second sample equal to n shall be taken and the original length.
the total defects of the n plus n units shall not exceed the 8.1.3 The elongation of wire with a nominal diameter equal
allowable defect number, c . Failure to meet this requirement to or less than 0.0808 in. (2.053 mm) may be determined as
shall constitute failure to meet the dimensional conformance describedaboveorbymeasurementsmadebetweenthejawsof
criterion. the testing machine. When measurements are made between
thejaws,thezerolengthshallbethedistancebetweenthejaws
6.4 Continuity of Coating—The continuity of the coating of
at the start of the tension test and be as near 10 in. (254 mm)
each of the eight specimens shall conform to the requirements
as practicable. The final length shall be the distance between
of 5.4. Failure of more than two specimens shall constitute
the jaws at the time of rupture. The fracture shall be between
failure to meet the continuity criterion. If not more than two
gage marks or jaws of the testing machine, depending on
specimens fail to meet the continuity criteria, eight additional
methodused,andnotcloserthan1in.(25.4mm)toeithergage
specimens from the lot shall be tested, all of which shall
mark or jaw.
conform to the continuity criteria. However, any individual
production unit, the specimen from which failed to meet the 8.2 Resistivity—The electrical resistivity of the material
continuity criteria, shall be rejected. shall be determined in accordance with Test Method B193
TABLE 2 Sampling for Dimensional Measurements and Surface Finish
First Sample Second Sample
Allowable
Allowable
Number of
Number of Number of
Number of Units
Number of
Defects in
Units in Units in
in Lot
Defects in n + n
1 2
Both Sample
Sample, Sample,
First Sample, 2
c
n n
1 2
c
1 to 14, incl All 0 . . .
15 to 50, incl 14 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
B298−12 (2017)
TABLE 3 Sampling for Packaging Inspection
exhausted if it fails to remove within 15 s the discoloration of
Allowable the silver due to the polysulfide immersion.
Number of
Number of Units Number of
8.4.3 Procedure:
Units in
in Lot Defective
Sample, n
8.4.3.1 Immersion in Polysulfide Solution—Immerse a
Units, c
length of at least 4 ⁄2 in. (114 mm) from each of the clean
1 to 30, incl all 0
31 to 50, incl 30 0
specimens for 30 s in the sodium polysulfide solution, de-
51 to 100, incl 37 0
scribed in 8.4.2.1, maintained at a temperature between 15.6
101 to 200, incl 40 0
and 21°C.
201 to 300, incl 70 1
301 to 500, incl 100 2
8.4.3.2 Washing—Aftert
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