ASTM D2305-18

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2305 − 10 D2305 − 18
Standard Test Methods for
Polymeric Films Used for Electrical Insulation
This standard is issued under the fixed designation D2305; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 These test methods cover the testing of homogeneous organic polymer films not over 2.4 mm (95 mils) thick that are to be
used for electrical insulation.
1.2 These test methods are not necessarily applicable to testing films in combinations with a coating, another film, or with other
types of substrate, such as fabrics or papers.
1.3 The values stated in SI units are the standard. The values in parentheses are provided for information only.
1.4 The procedures appear in the following sections:
Procedure Sections
Conditioning 5 and 6
Conditioning 6 and 7
Dielectric Breakdown Voltage & Dielectric Strength 20 to 25
Dielectric Breakdown Voltage & Dielectric Strength 21 to 26
Extractables 64 to 69
Extractables 65 to 70
Heat-Seal Strength 58 to 63
Heat-Seal Strength 59 to 64
Permittivity and Dissipation Factor 41 to 46
Permittivity and Dissipation Factor 42 to 47
Resistance Method for Measuring the Tendency to
Corrode Metals 37 to 40
Corrode Metals 38 to 41
Sampling 4
Sampling 5
Shrinkage 47 to 52
Shrinkage 48 to 53
Strain Relief 12 to 19
Strain Relief 13 to 20
Surface Resistivity 26 to 30
Surface Resistivity 27 to 31
Tensile Properties 11
Tensile Properties 12
Thickness 7 to 10
Thickness 8 to 11
Volume Resistivity 31 to 36
Volume Resistivity 32 to 37
Water Absorption 52 to 57
Water Absorption 53 to 58
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For a specific warning statement see 23.1.
NOTE 1—These test methods are similar to IEC 60674–2.
1.6 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.
These test methods are under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and are the direct responsibility of Subcommittee
D09.07 on Flexible and Rigid Electrical Insulating Materials.
Current edition approved Oct. 1, 2010May 1, 2018. Published October 2010June 2018. Originally published in 1964. Last previous edition approved in 20022010 as
D2305 – 02.D2305 – 10. DOI: 10.1520/D2305-10.10.1520/D2305-18.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2305 − 18
2. Referenced Documents
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D150 Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
D257 Test Methods for DC Resistance or Conductance of Insulating Materials
D374 Test Methods for Thickness of Solid Electrical Insulation (Metric) D0374_D0374M
D570 Test Method for Water Absorption of Plastics
D882 Test Method for Tensile Properties of Thin Plastic Sheeting
D883 Terminology Relating to Plastics
D1000 Test Methods for Pressure-Sensitive Adhesive-Coated Tapes Used for Electrical and Electronic Applications
D1531 Test Methods for Relative Permittivity (Dielectric Constant) and Dissipation Factor by Fluid Displacement Procedures
(Withdrawn 2012)
D1676 Test Methods for Film-Insulated Magnet Wire
D1711 Terminology Relating to Electrical Insulation
D5032 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Glycerin Solutions
D6054 Practice for Conditioning Electrical Insulating Materials for Testing (Withdrawn 2012)
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 IEC Standard:
Publication 60674–2 Specification for Plastic Films for Electrical Purposes
3. Terminology
3.1 Definitions:
3.1.1 Definitions are in accordance with Terminologies D1711 and D883 unless otherwise specified.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 sheet, n—material greater than 75 mm in width.
3.2.2 strain relief, n—relaxation at a specified elevated temperature of induced strains.
3.2.3 strip, n—material 75 mm or less in width.
4. Hazards
4.1 High Voltage:
4.1.1 Lethal voltages are a potential hazard during the performance of this test. It is essential that the test apparatus, and all
associated equipment electrically connected to it, be properly designed and installed for safe operation.
4.1.2 Solidly ground all electrically conductive parts which it is possible for a person to contact during the test.
4.1.3 Provide means for use at the completion of any test to ground any parts which were at high voltage during the test or have
the potential for acquiring an induced charge during the test or retaining a charge even after disconnection of the voltage source.
4.1.4 Thoroughly instruct all operators as to the correct procedures for performing tests safely.
4.1.5 When making high voltage tests, particularly in compressed gas or in oil, it is possible for the energy released at
breakdown to be sufficient to result in fire, explosion, or rupture of the test chamber. Design test equipment, test chambers, and
test specimens so as to minimize the possibility of such occurrences and to eliminate the possibility of personal injury. If the
potential for fire exists, have fire suppression equipment available. See section
5. Sampling
5.1 Remove the outer three or more layers down from the roll or stack of material before sampling.
5.2 If the film is known or suspected to be anisotropic for a given property, prepare and mark each test specimen to indicate
the axis of maximum orientation. The axis parallel to the direction of extrusion, or casting, is conventionally described as the
machine direction and is abbreviated MD. The axis that is normal to both the MD axis and the thickness axis is conventionally
described as the transverse direction and is abbreviated TD.
5.3 Prepare test specimens suitable for each test from samples that have been cut across the entire width of the sampled material.
If the width of strip material is too small to permit preparation of specimens of the required dimensions, then it is acceptable to
prepare specimens from samples taken from mill rolls prior to slitting to the furnished width.
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 the ASTM website.
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Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D2305 − 18
CONDITIONING
6. Significance and Use
6.1 Many electrical and physical properties of films vary significantly with changes in temperature and humidity. Properties of
thin plastic films can change very rapidly; therefore, the specimen needs to be in the stated conditioning environment when the
test is being performed. When the test is performed in a different environment, note these conditions and the time of exposure to
this new environment.
7. Procedure
7.1 Unless otherwise specified in the individual test methods, test the specimens in the Standard Laboratory Atmosphere 23 6
2°C, 50 6 5 % R.H. prescribed in Practice 10 % R.H.D6054.
THICKNESS
8. Significance and Use
8.1 The determination of film thickness is frequently necessary to ensure (1) the satisfactory production of electrical equipment,
and (2) the maintenance of desired electrical properties of the film during the use of the electrical equipment. Some properties, such
as dielectric strengths, vary with the thickness of the material; other properties, such as permittivity, cannot be calculated without
a proper determination of thickness unless special techniques are used.
9. Procedure
9.1 Use Method C of Test Methods D374 for this measurement, with the apparatus modified as follows: Use a presser foot of
6.25 6 0.05 mm (250 6 1 mil) diameter, and an anvil surface, upon which the specimen rests, of at least 50-mm (2-in.) diameter.
Apply a force of 0.84 6 0.2 N (3 6 0.75) ozf to the specimen. Take ten measurements, equally spaced throughout the specimen.
10. Report
10.1 Report the average, maximum, and minimum thicknesses to the nearest 0.5 μm (0.02 mil) for specimens thinner than 50
μm (2 mils) and to the nearest 1 μm (0.04 mil) for specimens 50 μm (2 mils) or more in thickness.
11. Precision and Bias
11.1 Precision—A formal round robin test in accordance with Practice E691 has not been conducted. Persons familiar with this
method have determined that two test results can be expected (with a probability of 95 %) to agree within 3 %. Each test result
is the average of 10 thickness readings taken on a single sample of polyimide film in one laboratory in which a multiple number
of operators used the same apparatus.
11.2 Bias—This test method has no bias because the value for thickness is determined solely in terms of this test method.
TENSILE PROPERTIES
12. Procedure
12.1 Use Method A of Test Methods D882. Report data only for the specific tests required by a specification.
12.2 Prepare five specimens in each of the two principal directions, each 12 by 200 mm (0.5 by 8 in.).
12.3 Unless otherwise stated, measure the tensile strength and tensile elongation, with initial jaw separation of 100 6 2 mm
(4.06 0.08 in.) and rate of jaw separation of 50 6 2 mm (2 6 0.08 in.)/min.
12.4 For each specimen, record the thickness and width prior to the application of the tensile force. Use these values to calculate
the tensile strength for each specimen. Report the tensile strength in MPa (lbf/in. ).
STRAIN RELIEF
13. Significance and Use
13.1 The strain relief test gives an indication of the dimensional changes that have the potential to occur when a film is exposed
to elevated temperatures during a manufacturing process or while in service.
14. Apparatus
14.1 Ovens, shall be of a forced-convection type capable of maintaining the specified temperature6 5°C.temperature 65°C.
14.2 Scale, graduated in 0.25-mm (0.01-in.) divisions with a total length of at least 300 mm (12 in.).
D2305 − 18
15. Test Specimen
15.1 Prepare test specimens 25 mm (1 in.) wide and at least 300 mm (12 in.) long. When sheets or rolls are greater than 300
mm wide, also cut specimens in the transverse direction.
16. Conditioning
16.1 Condition test specimens in accordance with Section 67 before the initial and final measurements are made.
17. Procedure
17.1 Mark gage lines on five specimens approximately 25 mm (1 in.) in from the ends of the specimen at a gage distance of
250 mm (10.0 in.). Determine the initial gage distance by measuring both edges of each specimen. Hang the specimen freely in
the oven at the time and temperature specified for the material. Determine the final gage distance by measurement after
conditioning.
17.1.1 Use a marking technique that does not affect the properties or dimensions of the material.
17.1.2 Adjust the air flow in the oven so that the specimens do not whip.
18. Calculation
18.1 Calculate the liner dimensional change as follows:
Linear change, %5 D 2 D /D 3100 (1)
@~ ! #
t v v
where:
D = final dimensions, in. (mm), and
t
D = original dimension, in. (mm).
v
A negative value denotes shrinkage, and a positive value indicates expansion.
18.2 Average the values obtained for each direction.
19. Report
19.1 Report the following information:
19.1.1 Identification of the material tested,
19.1.2 Test conditions (time and temperature), including the conditioning of the test specimens,
19.1.3 Average percentage linear change and maximum deviations, in both machine and transverse directions of the film, and
19.1.4 Any curl at the edges or other visual defects.
20. Precision and Bias
20.1 Precision—This test method has been in use for many years, but no information has been presented to ASTM upon which
to base a statement of precision. No activity has been planned to develop such information.
20.2 Bias—This test method has no bias because the value for strain relief is determined solely in terms of this test method itself.
DIELECTRIC BREAKDOWN VOLTAGE AND DIELECTRIC STRENGTH
21. Significance and Use
21.1 The dielectric breakdown voltage and dielectric strength of a film is an indication of its ability to withstand electric stress.
This value needs to be used primarily as an indication of quality and for comparison of different lots or types of the same material.
Secondarily, this value will potentially be useful as a design criterion, particularly when considering short term exposures,
providing that sufficient experience has been gained to give an adequate correlation between this test and the proposed end uses.
21.2 Unless special precautions are taken, these test results will potentially be just a measure of the quality of the electrode
surfaces and the electrical apparatus. This is especially true with thinner films.
21.3 For further details on the significance of this test, refer to Test Method D149.
22. Apparatus
22.1 Use apparatus that conforms to that specified in Test Method D149, including the 25-mm (1-in.) diameter electrodes
described therein. As an exception, the 6.4-mm ( ⁄4-in.) diameter electrodes are permitted where only narrow tape is available; and
note such exceptions in the report. For further details on electrodes refer to the electrode section of Test Method D149.
NOTE 2—Tests made with different size electrodes are not necessarily comparable. In many cases, a change in electrode size can make a significant
difference in test results. Take care to keep electrodes parallel, clean, and free of pits.
23. Test Specimen
23.1 Test clean specimens only. Surface contamination can form dents when the electrodes are applied to the specimen or can
alter the electrical field pattern, or both, to give erroneous results.
D2305 − 18
NOTE 3—To help prevent the specimen from becoming contaminated during the test, it is recommended that the tests be made in a clean, air-conditioned
room supplied with filtered air.
24. Procedure
24.1 Determine the dielectric breakdown voltage in air and dielectric strength in accordance with Test Method D149, and in
accordance with the applicable sections of this test method. Unless otherwise specified, make ten breakdown measurements,
equally spaced throughout the specimen.
NOTE 4—When testing films in a medium other than air, it is possible that different results will be obtained.
(Warning—Lethal voltages are a potential hazard during the performance of this test. It is essential that the test apparatus, and
all associated equipment electrically connected to it, be properly designed and installed for safe operation. Solidly ground all
electrically conductive parts which it is possible for a person to contact during the test. Provide means for use at the completion
of any test to ground any parts which were at high voltage during the test or have the potential for acquiring an induced charge
during the test or retaining a charge even after disconnection of the voltage source. Thoroughly instruct all operators as to the
correct procedures for performing tests safely. When making high voltage tests, particularly in compressed gas or in oil, it is
possible for the energy released at breakdown to be suffıcient to result in fire, explosion, or rupture of the test chamber. Design
test equipment, test chambers, and test specimens so as to minimize the possibility of such occurrences and to eliminate the
possibility of personal injury. If the potential for fire exists, have fire suppression equipment available.)
25. Application of Voltage
25.1 Unless otherwise specified, use the short-time test method with a rate of rise of 500 V/s.
26. Report
26.1 Unless otherwise specified, report the following information:
26.1.1 Average breakdown voltage,
26.1.2 Average thickness of breakdown specimens,
26.1.3 Average, maximum, and minimum dielectric strength (optional),
26.1.4 Ambient medium and ambient condition,
26.1.5 Conditioning of specimens,
26.1.6 Rate of voltage increase, and
26.1.7 Size and material of electrodes used.
SURFACE RESISTIVITY
27. Significance and Use
27.1 Surface resistivity is of value for determining the suitability of a material under severe service conditions such as high
temperature and high humidity. Its primary use needs to be as an indication of quality and for comparison of different lots or types
of the same material. Secondarily, it is possible that this test will be used to classify materials into broad groups that differ from
each other by at least one power of ten.
28. Conditioning
28.1 Use one or more of the following conditions (see Practice D6054):
28.1.1 Condition 18/35/90,
28.1.2 Condition 2/90, or
28.1.3 Condition 2/130.
29. Procedure
29.1 Determine the surface resistivity in the conditioning atmosphere in accordance with Test Methods D257, using strip
electrodes as shown in Fig. number 3 of that test method.
29.2 It is important that the specimens not be contaminated during the placement of the electrodes.
29.3 Do not allow the specimens used for test to contact unclean su
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