ASTM D748-14
(Specification)Standard Specification for Natural Block Mica and Mica Films Suitable for Use in Fixed Mica-Dielectric Capacitors
Standard Specification for Natural Block Mica and Mica Films Suitable for Use in Fixed Mica-Dielectric Capacitors
ABSTRACT
This specification covers the electrical, visual, and physical properties of natural blocks and films made from mica that are suitable for use in fixed mica-dielectric capacitors. The materials under this specification are of three forms and four classes. Samples should be taken and tested according to the test methods prescribed here. All samples should adhere to the specified values of conducting path, Q value, dielectric constant, weight loss on heating, thickness uniformity, temperature coefficient of capacitance and retrace, and amount of air inclusions, waves, cracks, tears, pin holes, stones, buckles, and ridges.
SIGNIFICANCE AND USE
4.1 The properties included in this specification are those required to identify the types of natural block mica and mica films (cut and uncut) suitable for use in the manufacture of fixed mica-dielectric capacitors. It is possible that other requirements will be necessary to identify particular characteristics. These will be added to the specification as their inclusion becomes generally desirable, and the necessary test data and methods become available. It is possible that natural block mica and mica films that do not conform to the requirements of this specification for capacitor use are capable of meeting the requirements for other critical electrical insulation purposes.
4.2 The system of classifying electrical quality of natural block and mica films (cut and uncut) covered by this specification is based on a combination of electrical and physical properties, and visual qualities specified herein, which the mica must possess. This system differs radically from past practices and previous concepts of mica quality for capacitor use. The electrical classification system does not discriminate against the presence of spots and stains in even first quality electrically selected mica, provided the mica conforms to specific and physical requirements. Appreciable amounts of air inclusions and waviness also are permitted in all electrical quality classes, provided the mica meets specific electrical and physical requirements. Mica meeting these requirements is acceptable without regard to color or origin. However, mica meeting these electrical and physical requirements but having lower visual quality than that meeting the requirements for the visual quality classification is not considered generally as desirable.
4.3 In capacitor fabrication, one or more pieces of cut film or block mica having lower than required electrical and physical properties will possibly prevent meeting the end requirements of the capacitor. It is therefore required that each piece of block ...
SCOPE
1.1 This specification covers natural block mica2 and mica films (cut and uncut) suitable for use in the manufacture of fixed mica-dielectric capacitors, based on electrical, visual, and physical properties as determined by tests specified herein.
1.2 The values stated in inch-pound units are to be regarded as standard.
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Designation:D748 −14
Standard Specification for
Natural Block Mica and Mica Films Suitable for Use in Fixed
1
Mica-Dielectric Capacitors
This standard is issued under the fixed designation D748; 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* istics.Thesewillbeaddedtothespecificationastheirinclusion
2 becomes generally desirable, and the necessary test data and
1.1 This specification covers natural block mica and mica
methods become available. It is possible that natural block
films (cut and uncut) suitable for use in the manufacture of
mica and mica films that do not conform to the requirements of
fixedmica-dielectriccapacitors,basedonelectrical,visual,and
this specification for capacitor use are capable of meeting the
physical properties as determined by tests specified herein.
requirements for other critical electrical insulation purposes.
1.2 The values stated in inch-pound units are to be regarded
4.2 The system of classifying electrical quality of natural
as standard.
block and mica films (cut and uncut) covered by this specifi-
2. Referenced Documents
cation is based on a combination of electrical and physical
3
properties,andvisualqualitiesspecifiedherein,whichthemica
2.1 ASTM Standards:
must possess. This system differs radically from past practices
D149 Test Method for Dielectric Breakdown Voltage and
and previous concepts of mica quality for capacitor use. The
Dielectric Strength of Solid Electrical Insulating Materials
electrical classification system does not discriminate against
at Commercial Power Frequencies
the presence of spots and stains in even first quality electrically
D351 Classification for Natural Muscovite Block Mica and
selected mica, provided the mica conforms to specific and
Thins Based on Visual Quality
physical requirements. Appreciable amounts of air inclusions
D1082 Test Method for Dissipation Factor and Permittivity
and waviness also are permitted in all electrical quality classes,
(Dielectric Constant) of Mica
provided the mica meets specific electrical and physical
2.2 ASTM Adjuncts:
requirements. Mica meeting these requirements is acceptable
Test electrodes
without regard to color or origin. However, mica meeting these
Grid test electrodes
electrical and physical requirements but having lower visual
3. Terminology qualitythanthatmeetingtherequirementsforthevisualquality
classification is not considered generally as desirable.
3.1 For definitions pertaining to this specification see Clas-
sification D351.
4.3 In capacitor fabrication, one or more pieces of cut film
or block mica having lower than required electrical and
4. Significance and Use
physical properties will possibly prevent meeting the end
4.1 The properties included in this specification are those
requirements of the capacitor. It is therefore required that each
required to identify the types of natural block mica and mica
piece of block (cut) or film (cut or uncut), or both, be tested for
films (cut and uncut) suitable for use in the manufacture of
the electrical requirements and inspected for the visual require-
fixed mica-dielectric capacitors. It is possible that other re-
ments listed in this specification.
quirements will be necessary to identify particular character-
5. Forms
1
This specification is under the jurisdiction of ASTM Committee D09 on
5.1 This specification covers the following three forms of
Electrical and Electronic Insulating Materials and is the direct responsibility of
natural mica, suitable for use in the manufacture of mica-
Subcommittee D09.01 on Electrical Insulating Products.
dielectric capacitors:
Current edition approved Nov. 1, 2014. Published December 2014. Originally
approved in 1943. Last previous edition approved in 2011 as D748 – 00 (2011).
5.1.1 Form 1—Full-knife trimmed natural block mica 0.007
DOI: 10.1520/D0748-14.
to 0.035 in. (0.18 to 0.89 mm) in thickness.
2
Coutlee, K. G., “Electrical Quality Classification of Raw Mica by a Rapid,
Direct-Reading Test Method,” Proceedings, ASTM, Vol 46, 1946, p. 1486.
5.1.1.1 It is acceptable for a certain percentage of block
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mica thinner than 0.007 in. to be accepted under this
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
specification, upon agreement between the purchaser and the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. manufacturer.
*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
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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: D748 − 00 (Reapproved 2011) D748 − 14
Standard Specification for
Natural Block Mica and Mica Films Suitable for Use in Fixed
1
Mica-Dielectric Capacitors
This standard is issued under the fixed designation D748; 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*
2
1.1 This specification covers natural block mica and mica films (cut and uncut) suitable for use in the manufacture of fixed
mica-dielectric capacitors, based on electrical, visual, and physical properties as determined by tests specified herein.
1.2 The values stated in inch-pound units are to be regarded as the standard.
2. Referenced Documents
3
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D351 Classification for Natural Muscovite Block Mica and Thins Based on Visual Quality
D1082 Test Method for Dissipation Factor and Permittivity (Dielectric Constant) of Mica
2.2 ASTM Adjuncts:
Test electrodes
Grid test electrodes
3. Terminology
3.1 For definitions pertaining to this specification see Classification D351.
4. Significance and Use
4.1 The properties included in this specification are those required to identify the types of natural block mica and mica films
(cut and uncut) suitable for use in the manufacture of fixed mica-dielectric capacitors. There may be It is possible that other
requirements will be necessary to identify particular characteristics. These will be added to the specification as their inclusion
becomes generally desirable, and the necessary test data and methods become available. Natural It is possible that natural block
mica and mica films that do not conform to the requirements of this specification for capacitor use may well be are capable of
meeting the requirements for other critical electrical insulation purposes.
4.2 The system of classifying electrical quality of natural block and mica films (cut and uncut) covered by this specification is
based on a combination of electrical and physical properties, and visual qualities specified herein, which the mica must possess.
This system differs radically from past practices and previous concepts of mica quality for capacitor use. The electrical
classification system does not discriminate against the presence of spots and stains in even first quality electrically selected mica,
provided the mica conforms to specific and physical requirements. Appreciable amounts of air inclusions and waviness also are
permitted in all electrical quality classes, provided the mica meets specific electrical and physical requirements. Mica meeting these
requirements is acceptable without regard to color or origin. However, mica meeting these electrical and physical requirements but
having lower visual quality than that meeting the requirements for the visual quality classification is not considered generally as
desirable.
1
This specification is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.19 on Dielectric Sheet and Roll Products.
Current edition approved April 1, 2011Nov. 1, 2014. Published April 2011December 2014. Originally approved in 1943. Last previous edition approved in 20052011 as
{1
D748 – 00 (2011). (2005) . DOI: 10.1520/D0748-00R11.10.1520/D0748-14.
2
Coutlee, K. G., “Electrical Quality Classification of Raw Mica by a Rapid, Direct-Reading Test Method,” Proceedings,ASTM, Vol 46, 1946, p. 1486.
3
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.
*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
1
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D748 − 14
4.3 In capacitor fabrication, one or more pieces of cut film or block mica having lower than required electrical and physical
properties may will possibly prevent meeting the end requirements of the capacitor. It is therefore required that each piece of block
(cut) or film (cut or uncut), or both, be tested f
...
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