4.1 This specification is a revision of STD MIL-M-14H, Specification for Molding Compound, Thermosetting, retaining the MIL-M-14H material designations and property requirements while conforming to ASTM form and style. It is intended for qualification and batch acceptance for materials used by government and industry, and is intended as a direct replacement for MIL-M-14H.

This specification covers the basic properties of thermoset molding plastic compounds and the test methods used to establish the properties. The plastic compounds shall be a resin, cellulose-filled or mineral/glass-filled phenolic, melamine, polyester, diallyl iso-phthalate, diallyl ortho-phthalate, silicone, or epoxy. Standard test specimens shall be in the as-received condition or shall be conditioned before testing by humidity, immersion, or temperature conditioning. The specimens shall undergo mechanical or physical qualification tests which shall conform to the following properties: compressive strength; dimensional stability; flexural strength; heat deflection temperature; heat resistance; impact strength; tensile strength; and water absorption. Electrical qualification tests shall be conducted; wherein, the specimens shall comply with the following requirements: arc resistance; dielectric breakdown; dielectric constant; dielectric strength; dissipation factor; surface resistance; comparative track index; volume resistance; and water extract conductance. Tests for combustion qualification shall also be performed to determine the flame resistance ignition time, burning time, flammability, and toxicity requirements. Batch acceptance tests shall be conducted as well to ensure the quality conformance of the specimens.

1.1 This specification covers the basic properties of thermoset molding compounds and the test methods used to establish the properties.

1.2 Classification—Molding thermosetting plastic compounds shall be of the following resins and are covered by the individual specification sheets (see 5.1 and Annex A1-Annex A8).

Resin

Phenolic, cellulose filled

Phenolic, mineral/glass filled

Melamine

Polyester

Diallyl iso-phthalate

Diallyl ortho-phthalate

Silicone

Epoxy

1.3 Order of Precedence—In the event of a conflict between the text of this specification and the references cited in Section 2 (except for related specification sheets), the text of this specification takes precedence. Nothing in this specification, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

1.4 The values stated in SI units are to be considered standard.