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【范围】
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1.1 Scope:
This specification covers class L, low dielectric constant (12 or under), ceramic, electrical, insulating
compounds, for use in electronic, communications, and allied electrical equipments, and the grading
thereof (see 6.1).
1.2 Classification:
This specification shall cover only those insulating compounds characterized by combining the
specific designators of 1.2.1 to 1.2.5, inclusive.
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1.2.1 Insulating compound designator: Insulating compounds shall be identified by the single letter
designator “L”.
1.2.2 Grade designators: Insulating compounds shall be further identified by three numbers (grade
designators) following the above designator, the first representing dielectric loss index at one
megahertz (MHz), the second dielectric strength, and the third flexural strength (modulus of
rupture), as specified, i.e., L422-- (see 6.1 and 6.2).
1.2.2.1 Dielectric loss index at 1 MHz: The designator for dielectric loss index is determined by the
maximum dielectric loss index at 1 MHz of the specimens tested, as follows:
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1.2.2.2 Dielectric strength: The designator for dielectric strength is determined by the average dielectric
strength of the specimens tested, as follows:
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1.2.2.3 Flexural strength (modulus of rupture): The designator for flexural strength (modulus of rupture)
is determined by the average flexural strength (modulus of rupture) of the specimens tested, as
follows:
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1.2.3 X-band designators: When insulating compounds are required for frequency applications from 100
MHz to 24 gigahertz (GHz), they shall be identified by the designator “X”, followed by a one-digit
number, a slant line, and a two-digit number. The one-digit number shall represent dielectric loss
index measured at some X-band frequency in the range from 8.2 GHz to 12.4 GHz, using the table
of grade designators of 1.2.2.1, and the two-digit number shall represent dielectric constant
measured at some X-band frequency (see 1.2.3.1), as specified (see 6.1 and 6.2).
1.2.3.1 Dielectric constant at X band: The designator for dielectric constant is determined by the
dielectric constant at some X band frequency in the range from 8.2 to 12.4 GHz of the specimens
tested as follows:
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1.2.4 Thermal conductivity designator: When high thermal conductivity (see 3.7) insulating compounds
are required, they shall be identified by the designator “T”, i.e., L422T-- or L422 X6/04T--. (See 6.1
and 6.2).
1.2.5 Finish designator: Insulating compounds shall be further identified by a single letter designator, “G”
or “C,” to represent finish, i.e., L323G, L323 X/04G, L323TG or L323 X6/04TG. (See 6.1 and 6.2).
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