ASTM D2148-95
(Test Method)Standard Test Methods for Bondable Silicone Rubber Tapes Used for Electrical Insulation
Standard Test Methods for Bondable Silicone Rubber Tapes Used for Electrical Insulation
SCOPE
1.1 These test methods cover tests for bondable silicone rubber tapes which form a sealed structure either with the application of heat (and pressure if needed) or by the process of auto-adhesion (self-fusing).
1.2 The methods appear in the following sections:Test MethodSectionAdhesion3-9 Bond Strength10-17 Dielectric Breakdown Voltage18-25 Hardness40Length 32 and 33Thickness26-31Width 35-39
1.3 The values stated in inch-pound units are to be regarded as the standard except for °C.
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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement see 22.1.1.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 2148 – 95 An American National Standard
Standard Test Methods for
Bondable Silicone Rubber Tapes Used for Electrical
Insulation
This standard is issued under the fixed designation D 2148; 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.
1. Scope D 2240 Test Method for Rubber Property—Durometer
Hardness
1.1 These test methods cover tests for bondable silicone
rubber tapes which form a sealed structure either with the
ADHESION
application of heat (and pressure if needed) or by the process
of auto-adhesion (self-fusing).
3. Scope
1.2 The methods appear in the following sections:
3.1 This test method covers the determination of the self-
Test Method Section
adhesion of unsupported, self-fusing silicone rubber rectangu-
lar and taper-edge (Note 1) tape designed for use as electrical
Adhesion 3-9
Bond Strength 10-17 insulation.
Dielectric Breakdown Voltage 18-25
NOTE 1—Taper-edge tape includes such cross sections as triangular,
Hardness 40
Length 32 and 33
lens, etc.
Thickness 26-31
Width 35-39
4. Significance and Use
1.3 The values stated in inch-pound units are to be regarded
4.1 Self-adhesion is a primary initial property since it affects
as the standard except for °C.
layer-to-layer bonding. The integrity of the bond can signifi-
1.4 This standard does not purport to address all of the
cantly affect the electrical and physical performance of the
safety concerns, if any, associated with its use. It is the
insulation system. Therefore, the degree of self-adhesion is
responsibility of the user of this standard to establish appro-
directly related to apparatus performance.
priate safety and health practices and determine the applica-
4.2 A high degree of self-adhesion is desirable for most
bility of regulatory limitations prior to use. For a specific
electrical applications. In this test, a short unwinding length
hazard statement see 22.1.1.
indicates a high degree of self-adhesion.
4.3 This test method has been found useful as a quality
2. Referenced Documents
control test for lot acceptance.
2.1 ASTM Standards:
5. Apparatus
D 149 Test Methods for Dielectric Breakdown Voltage and
Dielectric Strength of Solid Electrical Insulating Materials
5.1 Inclined Mandrel Tack Test Fixture— A suggested
at Commercial Power Frequencies
fixture is shown in Fig. 1. The mandrel shall consist of a ⁄8-in.
D 374 Test Methods for Thickness of Solid Electrical Insu-
(15.9-mm) diameter aluminum rod mounted in low-friction
lation
bearings. Good alignment of bearings is necessary for accurate
D 618 Practice for Conditioning Plastics and Electrical
results. When properly assembled, the mandrel shall turn freely
2,3
Insulating Materials for Testing
when loaded with a 30-g weight suspended from a cotton
D 1000 Test Methods for Pressure-Sensitive Adhesive
thread wound in a single layer at the center of the mandrel.
Coated Tapes Used for Electrical and Electronic Applica-
5.2 Weights, as specified in Section 7 and means for
tions
attachment.
D 1458 Test Methods for Fully Cured Silicone Rubber-
6. Test Specimen
Coated Glass Fabric and Tapes for Electrical Insulation
6.1 A test specimen shall consist of two pieces of tape 12 to
15 in. (25 to 38 mm) long. Divisions spaced 1 in. (25.4 mm)
apart shall be marked off on one piece of tape. If tapes contain
These methods are under the jurisdiction of ASTM Committee D-9 on
Electrical and Electronic Insulating Materials and are the responsibility of Subcom-
mittee D 09.07 on Flexible and Rigid Insulating Materials.
Current edition approved Jan. 15, 1995. Published March 1995. Originally Annual Book of ASTM Standards, Vol 09.01.
published as D 2148 – 63 T. Last previous edition D 2148 – 90. A detailed drawing of a suggested fixture is available at a nominal cost from
Annual Book of ASTM Standards, Vol 10.01. ASTM Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
Annual Book of ASTM Standards, Vol 08.01. Request Adjunct No. ADJD2148.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2148
record the length of tape unwound in 3 min. Although the
original 1-in. dimensions will elongate due to the unwind
weight, consider each division as one unit. While the winding
weights are not critical, the use of proper unwinding weights is
mandatory. Consistent and comparable results depend upon
accurate width measurements and the use of the proper
unwinding weight.
NOTE 2—Commercial tapes are usually made to a 6 ⁄16-in. (61.59-
mm) tolerance. Therefore a 600-g weight shall be used for tapes varying
15 1
in width from ⁄16 to 1 ⁄16in. (23.8 to 27 mm); a 750-g weight shall be used
3 5
for tapes varying in width from 1 ⁄16 to 1 ⁄16 in. (30.2 to 33.3 mm) and a
7 9
900-g weight shall be used for tapes varying in width from 1 ⁄16 to 1 ⁄16in.
(36.5 to 39.7 mm). Tapes with widths outside these ranges shall be tested
in accordance with their width (determined to the nearest ⁄16 in. (1.59
mm). For example, a 1 ⁄8-in. (28.6 mm) wide tape shall be tested with a
675-g weight. The unwinding weights shall be made to a tolerance of6
2%.
8. Report
8.1 Report the following information:
FIG. 1 Inclined Mandrel Tack Test Fixture
8.1.1 Description of material, type of cross-section, tape
width and thickness,
8.1.2 Winding weight, in grams,
an interliner, the interliner shall be removed just prior to
8.1.3 Unwinding weight, in grams, and
wrapping the mandrel. Dirt and other forms of contamination
8.1.4 Length of unwind, to the nearest ⁄4 unit.
shall be avoided.
9. Precision and Bias
7. Procedure
9.1 The precision of this test method has not been deter-
7.1 Winding—Half lap the unmarked specimen perfectly on
mined. Since there is no accepted reference material, no
the mandrel of the test fixture, using the suggested weight as
statement on bias is being made.
shown in Table 1. These weights are not critical. However, they
are necessary to get intimate contact and conformability of the
BOND STRENGTH
tape. To obtain perfect half lapping, tilt the tack tester at an
10. Terminology
appropriate angle as shown in Fig. 1. Wrap the tape on the
mandrel at a speed of approximately 18 in. (450 mm)/min.
10.1 Definitions of Terms Specific to This Standard:
Using the winding procedure and weights just described, half
10.1.1 bond strength, of unvulcanized and semivulcanized
lap the marked tape sample on the mandrel over the first piece
supported silicone rubber tapes—the strength of chemical
of tape. With the winding weight attached, return the test
linkages achieved between successive layers of tape under
fixture to a horizontal position and allow the tape to bond for
controlled vulcanizing conditions.
1 min. Remove the winding weight from the tape and the
11. Significance and Use
handle from the fixture and proceed with the unwinding test.
7.2 Unwinding—After the tape has bonded for 1 min, attach
11.1 The bond strength is an indication of the physical
a load of 600 g/in. of the original tape width (Note 2). Attach
integrity that can be expected under end use conditions in
the weight to the free end of the tape by means of a bulldog
which the insulating tapes are applied with an overlap.
paper clamp or other suitable device. Release the weight and
12. Apparatus
12.1 Bonding Press—A platen press having the following
TABLE 1 Suggested Winding Weights For 1-in. Wide Tapes
characteristics:
NOTE 1—Winding weights are based on cross-sectional area and have
12.1.1 A temperature range to 205°C (400°F).
been selected to produce approximately the same unit stress on all
12.1.2 A thermostat that will allow a set temperature to be
cross-sections. For tapes of dimensions not listed, use a winding weight of
maintained 69°F (65°C).
2 2
approximately 300 g/0.01 in. (6.3 mm )
12.1.3 A pressure regulator to allow setting and control of
Tape Thickness, in. (mm)
the platen pressure.
Weight, g
Triangular Rectangular
12.1.4 A pressure indicator to show the pressure being
0.020 (0.51) 0.010 (0.25) 300
exerted between the platen faces.
0.030 (0.76) 0.015 (0.38) 450
12.1.5 A timer to allow measurement of bonding time. It is
0.040 (1.02) 0.020 (0.51) 600
0.050 (1.27) 0.025 (0.64) 750 preferred that a controller-type timer be used which will both
0.060 (1.52) 0.030 (0.76) 900
indicate bonding time and also cause the platen pressure to be
0.070 (1.78) . 1050
released and the platens separated at the end of the bonding
0.080 (2.03) . 1200
period.
D 2148
12.2 Temperature-Measuring Device(s) to indicate face 16. Report
temperature of the platen(s).
16.1 Report the following information:
12.3 Silicone Rubber Pad, approximately ⁄8 in. (3.20 mm)
16.1.1 Bond strength of each specimen and the average in
thick, 60 to 70 Shore A durometer hardness, larger in dimen-
pounds per inch or newtons per metre of width, and
sion than the specimens to be tested. This is used as a
16.1.2 Bonding time, pressure, and temperature used, if
pressure-equalizing device, compensating for irregularities in
other than as specified.
either the specimen or the platens.
17. Precision and Bias
12.4 Polytetrafluoroethylene or suitable release film, three
sheets, approximately 2 to 4 mils (0.05 to 0.10 mm) thick. One
17.1 The precision of this test method has not been deter-
sheet is placed on each side of the specimens as a release sheet,
mined. Since there is no accepted reference material, no
the third sheet being used to separate the ends of the two test
statement on bias is being made.
specimens.
12.5 Testing Machine—A power-driven testing machine of DIELECTRIC BREAKDOWN VOLTAGE
either the cross head or dead-weight pendulum type. The
18. Scope
machine shall be equipped with a tension weighing device
18.1 This test method covers determination of the break-
having a maximum capacity of 50 lb (22.7 kg) graduated to
down voltage of unsupported bondable silicone rubber tapes
read 0.1 lb (50 g) or less per scale division.
with tapered edges (Note 3) for use as electrical insulation.
18.2 The method to be used for rectangular cross section
13. Test Specimen
tapes is described in Test Methods D 1458.
13.1 The test specimen shall be selected to be representative
of the material to be tested. The size of sample shall be
NOTE 3—Tapes with tapered edges include such cross sections as
sufficient to give six strips at least 1.25 to 1.5 in. (32 to 38 mm) triangular and lens-shaped.
wide and 6 in. (150 mm) long. Care should be taken to prevent
19. Significance and Use
contamination.
19.1 The level of dielectric breakdown voltage as deter-
mined by this test is one measure of the quality of both material
14. Conditioning
and fabrication methods used in producing the tape. This
14.1 The specimen shall not be exposed to temperatures
voltage value should not be compared directly with the results
above 85°F (30°C) before bonding. The tests shall be con-
of tests made on rectangular cross section tapes. For further
ducted in the Standard Laboratory Atmosphere as described in
details, refer to Test Method D 149.
Practice D 618.
20. Apparatus
15. Procedure
20.1 Test Fixture, designed to support a removable mandrel
15.1 Cut the strips of material to 1.25 to 1.5 in. (32 to 38
⁄8 in. (15.9 mm) in diameter and about (20 in.) (500 mm) in
mm) wide and at least 6 in. (150 mm) long, the length being
length. This fixture may be a modification of the one described
measured in the warp or machine direction of the backing.
in 5.1.
15.2 Remove any interliner material.
20.2 Voltage Source, capable of applying alternating voltage
15.3 Superimpose one strip on another, front side to back
and increasing it at the rate of 500 V/s. This equipment shall
side, to form a specimen.
conform to the requirements of Test Method D 149.
15.4 Separate the two strips at one end for a distance of
about 1 in. (25 mm) and insert a strip of release film.
21. Test Specimen
15.5 Preheat the press to 177°C (350°F).
21.1 The test specimen shall consist of lengths of bondable
15.6 Assemble the test specimens between two sheets of
tape about 0.75 to 2 in. (19 to 50 mm) wide and of sufficient
release film. Place the assembly on the unheated silicone
length to cover the entire mandrel.
rubber pad and insert in the press.
21.2 Adjust the mandrel to such an angle as will provide a
15.7 Close the press and apply 50 psi (345 kPa) pressure to
half-lapped tape on winding. Wrap the tape on the mandrel at
the specimens for 5 min.
a linear speed of 18 in./min using the winding weight shown in
15.8 Release the pressure, remove the specimens, and allow
Table 2.
them to cool for at least 5 min.
15.9 Remove the release film and trim the specimens to a
TABLE 2 Winding Weights
1-in. (25-mm) width.
Nominal Thickness of Tape
15.10 Clamp one separated end in the upper jaw of the
Winding Weight, g
in. mm
testing machine; peel the other separated end back 180 deg and
0.02 0.5 300
clamp it in the lower jaw.
0.03 0.75 450
15.11 Adjust the testing machine to provide a jaw separation
0.04 1.0 600
rate of 20 in. (500 mm) per min. If the pendulum-type machine 0.05 1.25 750
0.06 1.5 900
is used, disengage the pawls during the test. Record the average
0.07 1.75 1050
observed force for each specimen using the technique de-
0.08 2.0 1200
scribed for adhesion strength in Test Methods D 1000.
D 2148
m
NOTE 4—Winding weights are based on cross sectional area and have
V 5 V t /t ! (1)
~
2 1 2 1
been selected to approximate the same unit stress for all cross sections.
For tapes of dimensions other than listed, use a winding weight of about
2 2
300 g/0.01 in. (6.3 mm ).
where:
V = actual breakdown voltage for measured thickness, t ,
1 1
21.3 Apply foil electrodes 0.0005 to 0.002 in. (0.013 to
V = corrected breakdown voltage for nominal thickness,
0.050 mm) thick by 1 in. (25 mm) wide over the tapes,
t , and
allowing approximately 4 in. (100 mm) between electrodes and
m = constant (approximately 0.60 for bondable silicone
from electrodes to the end of the mandrel (Note 5). For
rubber tape).
example, in evaluating 0.030-in. (0.75-mm) tapes, three elec-
NOTE 6—This expression is an equation for a straight line using log-log
trodes shall be placed on a 20-in. (500-mm) long mandrel.
graph paper. The exponential constant m is the slope of this line as plotted,
Thicker tapes which require higher voltage to failure may
and has been determined empirically.
require more distance between electrodes in order to avoid
flashover.
24. Report
NOTE 5—Int
...
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