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).

This specification shall cover only those insulating compounds characterized by combining the specific designators of 1.2.1 to 1.2.5, inclusive.

L 4 4 2 X6/04 T B Class (1.2.1) Dielectric Dielectric Flexural X-band Thermal Finish loss index strength strength (when conduc- (1.2.5) (1.2.2.1) (1.2.2.2) (modulus specified) tivity of rup- (1.2.3) (when ture) specified (1.2.2.3) (1.2.4)

Insulating compounds shall be identified by the single letter designator "L".

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., I422-- (see 6.1 and 6.2).

The designator for dielectric loss index is determined by the maximum dielectric loss index at 1 MHz of the specimens tested, as follows:

Grade Maximum designator dielectric loss index 2 0.070 3 .035 4 .016 5 .008 6 .004 7 .002 8 .001

The designator for dielectric strength is determined by the average dielectric strength of the specimens tested, as follows:

Grade Average designator dielectric strength volts/mil 1 180 to 199, incl 2 200 to 249, incl 3 250 to 299, incl 4 300 and above

The designator for flexural strength (modulus of rupture ) is determined by the average flexural strength (modulus of rupture) of the specimens tested, as follows:

Average Grade flexural strength designator pounds/sq. in. 1 7,000 to 11,900, incl 2 12,000 to 19,900, incl 3 20,000 to 29,900, incl 4 30,000 to 34,900, incl 5 35,000 to 49,900, Incl 6 50,000 and above

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, line, and a two-digit number. The one-digit number shall represent dielectric loss index measured at some X-bend frequency in the range from 8.2 GHz to 12.4 GHz, using the table of grade designators of 1.2.2.1, end 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).

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:

Grade designator Dielectric constant 12 11.6 - 12 11 10.6 - 11.5 10 9.6 - 10.5 09 8.6 - 9.5 08 7.6 - 8.5 07 6.6 - 7.5 06 5.6 - 6.5 05 4.6 - 5.5 04 3.6 - 4.5 03 2.6 - 3.5 02 1.6 - 2.5 01 1.0 - 1.5

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)

Insulating compounds shall be further identified by a single letter designator, "B," "W," or"C," to represent finish, i.e., L323B, L323 X/04B, L323TB or L323 X6/04FB. (See 6.1 and 6.2)

Symbol Finish B - - - - Brown glaze. Glass and glass-bonded mica are not included. W - - - - White glaze. Glass and glass-bonded mica are not included. C - - - - Natural vitreous surface. Includes the fired ceramics, e.g., porcelain, steatite, and alumina; and the non- fired ceramics, e.g., glass and glass-bonded mica.

intended Use: