NPFC - MIL-I-46058
INSULATING COMPOUND, ELECTRICAL (FOR COATING PRINTED CIRCUIT ASSEMBLIES)
|Publication Date:||22 December 1966|
This specification covers four types of conformal coatings which are suitable for application to printed circuit assemblies by dipping, brushing, or spraying.
Type ER. Epoxy resin coating is intended for use where the best electrical properties are required for a general purpose coating, is intended to be used as a brush, spray, or... View More
Type ER. Epoxy resin coating is intended for use where the best electrical properties are required for a general purpose coating, is intended to be used as a brush, spray, or dip-coat application on glass or paper epoxy laminates.
Type PUR. Polyurethane resin coating is intended for use where god This coating is resistance to moisture and abrasion is required. suitable for continuous operation up to 125°C.
Type SR. Silicone coating is intended where excellent dielectric and high arc resistance properties are required for use at continuous operating temperatures up to 200OC.
Type PO. Polystyrene coating is suitable for continuous operation up to 85 °C, where best dielectric properties are required.
Selection. The selection of coating should be such that
the curing process shall have no harmful effects on the parts or
materials coated. covered by this specification are not suitable
for use on boards fabricated from types 8 and GT
Q (resonance) and dissipation factor information. The average Q for uncoated type GB laminate at frequencies of 1, 50, and 100 Megahertz (MHz) is 54 +8, 84 +11, and 40 +7, respectively, and dissipation factor at 1, 50, and 100 mc is 0.022 maximum, 0.014 maximum, and 0.030 maximum, respectively. It should be noted that when boards are coated more than 0.0020 inch thickness, the Q factor begins to drop rapidly; coating thickness in range of 0.001 to 0.002 inch range gives maximum protection of the electrical qualities of the circuit,View Less