ASTM B971-10(2020)e1
(Specification)Standard Specification for Silver-Coated Braid and Ribbon Flat Copper Wire intended for use in Electronic Application
Standard Specification for Silver-Coated Braid and Ribbon Flat Copper Wire intended for use in Electronic Application
ABSTRACT
This specification covers silver-coated copper braid and ribbon flat wire intended for electronic application. Two classes of silver-coated braid and ribbon flat copper wire are covered: Class A (annealed temper) and Class H (hard-drawn). The material shall be silver-coated flat wire of such quality and purity that the finished product shall meet the properties and characteristics prescribed in this specification. The specification covers tensile properties, electrical resistivity requirements, permissible variations in thickness, and permissible variations in width.
SCOPE
1.1 This specification covers silver-coated copper braid and ribbon flat wire intended for electronic application (Explanatory Note 1).
1.2 Two classes of silver-coated braid and ribbon flat copper wire are covered as follows:
1.2.1 Class A—Annealed temper.
1.2.2 Class H—Hard-drawn.
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 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
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
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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.
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Designation:B971 −10 (Reapproved 2020)
Standard Specification for
Silver-Coated Braid and Ribbon Flat Copper Wire intended
for use in Electronic Application
This standard is issued under the fixed designation B971; 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.
ε NOTE—Editorial corrections were made to 6.4.1.2 and Explanatory Note 7 in January 2020.
1. Scope B49Specification for Copper Rod for Electrical Purposes
B193Test Method for Resistivity of Electrical Conductor
1.1 This specification covers silver-coated copper braid and
Materials
ribbon flat wire intended for electronic application (Explana-
B258Specification for Standard Nominal Diameters and
tory Note 1).
Cross-Sectional Areas of AWG Sizes of Solid Round
1.2 Twoclassesofsilver-coatedbraidandribbonflatcopper
Wires Used as Electrical Conductors
wire are covered as follows:
2.2 Other Standards:
1.2.1 Class A—Annealed temper.
NBS Handbook 100Copper Wire Tables
1.2.2 Class H—Hard-drawn.
1.3 The values stated in inch-pound units are to be regarded 3. Ordering Information
as standard. The values given in parentheses are mathematical
3.1 Ordersformaterialunderthisspecificationshallinclude
conversions to SI units that are provided for information only
the following information:
and are not considered standard.
3.1.1 Quantity of each size,
1.3.1 Exceptions—The SI values for density, resistivity, and
3.1.2 Wire size-thickness and width in inches (see 5.4),
volume are to be regarded as standard.
3.1.3 Class of wire (see 1.2),
1.4 This standard does not purport to address all of the
3.1.4 Type of copper, if special (see 4.2),
safety concerns, if any, associated with its use. It is the
3.1.5 Package size (see 10.1),
responsibility of the user of this standard to establish appro-
3.1.6 Special packaging marking, if required, and
priate safety, health, and environmental practices and deter-
3.1.7 Place of inspection (see 7.1).
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 4. Material
dance with internationally recognized principles on standard-
4.1 The material shall be silver-coated flat wire (Explana-
ization established in the Decision on Principles for the
toryNote1)ofsuchqualityandpuritythatthefinishedproduct
Development of International Standards, Guides and Recom-
shall meet the properties and characteristics prescribed in this
mendations issued by the World Trade Organization Technical
specification.
Barriers to Trade (TBT) Committee.
4.2 Copper-Base Metal—The base metal shall be copper of
such quality and purity that the finished product shall have
2. Referenced Documents
2 properties and characteristics prescribed in this specification.
2.1 ASTM Standards:
NOTE 1—Specifications B1, B3,or B49 define copper suitable for use.
B1Specification for Hard-Drawn Copper Wire
B3Specification for Soft or Annealed Copper Wire
5. General Requirements (See Section 8)
5.1 Temper—The silver-coated flat wire conductor shall be
This test method is under the jurisdiction of ASTM Committee B01 on provided in either hard-drawn condition (Class H) or annealed
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
condition (Class A) as agreed upon between the manufacturer
Conductors of Copper and Copper Alloys.
and purchaser.
Current edition approved Jan. 1, 2020. Published January 2020. Originally
approved in 2010. Last previous edition approved in 2014 as B971–10 (2014).
5.2 Tensile and Elongation (Explanatory Note 2):
DOI: 10.1520/B0971-10R20E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from National Technical Information Service (NTIS), 5285 Port
the ASTM website. Royal Rd., Springfield, VA 22161, http://www.ntis.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B971−10 (2020)
TABLE 2 Electrical Resistivity Requirements
5.2.1 Class A—The silver-coated copper flat wire in the
annealed condition shall conform to the elongation require- Class of Wire Ω·lb/mile
ments prescribed in Table 1. See Explanatory Note 3 for
A 875.20
equivalent round diameter calculations based on given thick-
H 902.27
nessandwidthdimensionsfortheflatwire.Forflatwirewhose
nominal equivalent round diameter is more than 0.001 in.
(0.025 mm) greater than a size listed in Table 1, but less than TABLE 3 Permissible Variations in Thickness
that of the next larger size, the requirements of the next larger
Nominal Thickness Tolerance,
Range, Inch (mm) Inch (mm)
size shall apply. No requirements for tensile strength are
specified.
0.0010 to 0.0014 +/- 0.0002
5.2.2 Class H—The silver-coated copper flat wire in the
(0.025 to 0.036) (0.005)
0.0015 to 0.0019 +/- 0.0003
hard-drawnconditionshallconformtoelongationrequirements
(0.038 to 0.048) (0.008)
of 1% minimum to 5% maximum. The tensile strength shall
0.0020 to 0.0049 +/- 0.0004
be 55000 psi (379 MPa) minimum.
(0.051 to 0.124) (0.010)
0.0050 to 0.0100 +/- 0.0005
5.3 Resistivity (Explanatory Note 4)—The electrical resis-
(0.127 to 0.254) (0.013)
tivity of the coated wire at a temperature of 20°C shall not
exceed the values prescribed in Table 2.
TABLE 4 Permissible Variations in Width
5.4 Dimensions and Permissible Variations—The flat wire
Nominal Width Range, Tolerance,
sizes shall be expressed as the thickness and width of the wire
Inch (mm) Inch (mm)
indecimalfractionsofaninchtothenearest0.0001in.(0.0025
mm). The silver-coated flat wire shall not vary from the 0.0100 to 0.0499 +/- 0.0013
(0.254 to 1.27) (0.033)
specified thickness and width by more than the amounts
0.0500 to 0.0699 +/- 0.0015
specified in Table 3 and Table 4, respectively.
(1.27 to 1.78) (0.038)
0.0700 to 0.0999 +/- 0.0020
5.5 Continuity of Coating—The silver coating shall be
(1.78 to 2.54) (0.051)
continuous. The continuity of coating on the flat wire shall be
0.1000 to 0.1249 +/- 0.0030
(2.54 to 3.17) (0.076)
determined on representative samples taken before braiding
0.1250 to 0.1500 +/- 0.0040
applications or insulating. The continuity of coating shall be
(3.18 to 3.81) (0.102)
determined by the hydrochloric acid-sodium polysulfide test in
accordance with 6.4. Wire whose coating weight corresponds
to a thickness less than 40 µ in. (0.00004 in.) shall not be
coating shall be determined in accordance withTest MethodA
subject to this test (Explanatory Note 5). The thickness of
as prescribed in Appendix X1.
5.6 Joints—Necessary joints in the wire and rods prior to
A
TABLE 1 Tensile Properties
finalcoatinganddrawingshallbemadeinaccordancewiththe
Equivalent Area at 20°C Elongation in 10
best commercial practice. There shall be no uncoated joints in
Round in.,
the final product.
Diameter, in. min, %
cmils in.
5.7 Finish—The coating shall consist of a smooth continu-
0.0641 4 110 0.00323 25
ouslayer,firmlyadherenttothesurfaceofthecopper.Thewire
0.0571 3 260 0.00256 25
0.0508 2 580 0.00203 25
shall be free of all imperfections not consistent with the best
0.0453 2 050 0.00161 25
commercial practice.
0.0403 1 620 0.00128 25
0.0359 1 290 0.00101 25
6. Test Methods
0.0320 1 020 0.000804 25
0.0285 812 0.000638 25
6.1 Tensile Strength and Elongation (Explanatory Note 6):
0.0253 640 0.000503 25
0.0226 511 0.000401 25 6.1.1 The tensile strength, expressed in pounds per square
0.0201 404 0.00317 20
inch, shall be obtained by dividing the maximum load carried
0.0179 320 0.000252 20
by the specimen during the tension test by the original
0.0159 253 0.000199 20
0.0142 202 0.000158 20 cross-sectional area of the specimen. Tensile strength and
0.0126 159 0.000125 20
elongation may be determined simultaneously on the same
0.0113 128 0.000100 20
specimen.
0.0100 100 0.0000785 20
0.0089 79.2 0.0000622 15
6.1.2 The elongation shall be determined as the permanent
0.0080 64.0 0.0000503 15
increase in length, expressed in percent of the original length,
0.0071 50.4 0.0000396 15
due to the wire breaking in tension. The elongation of the flat
0.0063 39.7 0.0000312 15
0.0056 31.4 0.0000246 15
wire may be determined by measurements made between the
0.0050 25.0 0.0000196 15
jawsofthetensiletestingmachine.Thezerolengthshallbethe
0.0045 20.2 0.0000159 15
distance between the jaws at the start of the tension test and be
0.0040 16.0 0.0000126 15
A asnear10in.(254mm)aspracticable.Thefinallengthshallbe
See Explanatory Note 3 for equivalent round calculation.
the distance between the jaws at the time of rupture. The
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B971−10 (2020)
fracture shall be between the jaws of the testing machine and 6.4.3.2 Washing—Aftertheimmersion,thoroughlywashthe
not closer than 1 in. (25.4 mm) to the jaw. specimens in clean water and wipe dry with a clean, soft cloth.
6.4.3.3 Immersion in Hydrochloric Acid—After washing,
6.2 Resistivity (Explanatory Note 4)—The electrical resis-
immediately immerse the specimen 15 s in the HCl solution
tivity of the material shall be determined in accordance with
described in 6.4.2.2, thoroughly wash in clean water, and wipe
TestMethodB193.Thepurchasermayacceptcertificationthat
dry with a clean, soft cloth.
the wire was drawn from rod stock meeting the international
6.4.3.4 Examination of Specimens—After immersion and
standard for annealed copper instead of resistivity tests on the
washing examine the specimens to ascertain if copper exposed
finished wire.
through openings in the silver coating has been blackened by
6.3 Dimensional Measurements—Dimensional measure-
action of the sodium polysulfide. Examine the specimen with
mentsforwidthandthicknessshallbemadewithamicrometer
the unaided eye (normal spectacles excepted) against a white
caliperequippedwithaverniergraduatedin0.0001in.(0.0025
background. The specimens shall be considered to have failed
mm). Measurements shall be made on at least three places on
if,bysuchblackeningexposedcopperisrevealed.Noattention
each unit selected for this test. Any measurement taken
shall be paid to blackening within 0.5 in. (12.7 mm) of the cut
exceeding the dimensions and permissible variation require-
end.
ments in 5.4 shall constitute failure to meet the dimensional
6.5 Finish—Surface-finishinspectionshallbemadewiththe
conformance criterion.
unaided eye (normal spectacles excepted).
6.4 Continuity of Coating:
6.4.1 Specimens:
7. Inspection
6.4.1.1 Length of Specimens—Test specimens shall each
7.1 General (Explanatory Note 9)—Unless otherwise speci-
have a length of about 6 in. (152 mm).They shall be tagged or
fied in the contract or purchaser order, the manufacturer shall
marked to correspond with the coil, spool, or reel from which
be responsible for the performance of all inspection and test
they were cut.
requirements specified.
6.4.1.2 Treatment of Specimens—Thoroughly clean the
7.1.1 All inspections and tests shall be made at the place of
specimens by immersion in a suitable organic solvent for at
manufacture unless otherwise especially agreed upon between
least 3 min; then remove and wipe dry with a clean, soft cloth
the manufacturer and the purchaser at the time of purchase.
(Warning—SeeExplanatoryNote7).Keepthespecimensthus
7.1.2 The manufacturer shall afford the inspector represent-
cleaned wrapped in a clean, dry cloth until tested. Do not
ing the purchaser all reasonable manufacturer’s facilities to
handle that part of the specimen to be immersed in the test
satisfy him that the material is being furnished in accordance
solution. Take care to avoid abrasion by the cut ends.
with this specification.
6.4.2 Special Solutions:
7.1.3 Unless otherwise agreed upon between the purchaser
6.4.2.1 Sodium Polysulfide Solution (sp gr 1.142)—Make a
and the manufacturer, conformance of the wire to the various
concentrated solution by dissolving sodium sulfide crystals
requirementslistedinSection5shallbedeterminedonsamples
(cp) in distilled water until the solution is saturated at about
taken from each lot of wire presented for acceptance.
21°C, and adding sufficient flowers of sulfur (in excess of 250
7.1.4 The manufacturer shall, if requested prior to
g/L of solution) to provide complete saturation, as shown by
inspection, certify that all wire in the lot was made under such
the presence in the solution of an excess of sulfur after the
conditions that the product as a whole conforms to the
solution has been allowed to stand for at least 24 h. Make the
requirements of this specification as determined by regularly
test solution by diluting a portion of the concentrated solution
made and recorded tests.
with distilled water to a specific gravity of 1.135 to 1.145 at
15.6°C. The sodium polysulfide test solution should have
7.2 Definitions Applicable to Inspection:
sufficient strength to blacken thoroughly a piece of clean
7.2.1 lot—any amount of wire of one type and size pre-
uncoated copper wire in 5 s.Aportion of the test solution used
sented for acceptance at one time.
for testing samples shall not be considered to be exhausted
7.2.2 Sample—a quantity of production units (coils, reels,
until it fails to blacken a piece of clean copper as described
andsoforth)selectedatrandomfromthelotforthepurposeof
(Explanatory Note 8):
determining conformance of the lot to the requirements of this
6.4.2.2 Hydrochloric Acid Solution (sp gr 1.088)—Dilute
specification.
commercial HCl (sp gr 1.12) with distilled water to a specific
7.2.3 Specimen—a length of wire removed for test purposes
gravity of 1.088 measured at 15.6°C. A portion of the HCl
from any individual production unit of the sample.
solution having a volume of 180 mL shall be considered
7.3 Sample Size (Explanatory Note 9)—The number of
exhausted if it fails to remove within 15 s the discoloration of
the silver due to the polysulfide immersion. production units in a sample shall be as follows:
7.3.1 A full (100 % inspection) will be completed at every
6.4.3 Procedure:
set-up prior to running the order.
6.4.3.1 Immersion in Polysulfide Solution—Immerse a
length of at least 4.5 in. (114 mm) from each of the clean 7.3.2 Forelongation,resistivity,dimensionalmeasurements,
specimens for 30 s in the sodium polysulfide solution, de- continuity of coating, and thickness of coating determinations,
scribed in 6.4.2.1, maintained at a temperatur
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