Flame retardant B-staged epoxy resin prepregs and laminates made therefrom
AssigneeWestinghouse Electric Corp.
InventorsJoseph R. Marchetti, Wilbur R. Thomas
Life of this patent
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Abstract
A prepreg useful in flame resistant copper clad printed circuit boards is made by impregnating a porous substrate with an impregnant containing: either a prebrominated epoxy resin or a mixture of a non-halogenated epoxy resin and flame retarding additive containing bromine, and phenolic hydroxyl groups. A phenolic novolac oligomer having an average of over 2.5 phenolic hydroxyl groups per oligomeric unit is used as curing agent. Optionally, a suitable catalyst may be included. The impregnated substrate is heated to cure or advance the resin to the "B"-stage.
Claims23
A porous substrate impregnated with a "B"-staged resin, the resin comprising a mixture of:
- (I) a brominated epoxy resin, or
- (II) a mixture of (A) a non-halogenated epoxy resin and (B) a flame retarding reactive additive containing bromine and phenolic hydroxyl groups, and
- (III) phenolic novolac oligomer curing agent having an average of over 2.5 phenolic hydroxyl groups per oligomeric unit.
A flame resistant, heat and pressure consolidated laminate comprising:
- (I) at least one metal foil outer layer,
- (II) a support layer comprising at least one resin impregnated sheet, bonded to the metal foil, the sheet impregnated with a cured resin reaction product admixture of:
- (I) a brominated epoxy resin, or
- (II) a mixture of (A) a non-halogenated epoxy resin and (B) a flame retarding reactive additive containing bromine and phenolic hydroxyl groups, and
- (III) phenolic novolac oligomer curing agent having an average of over 2.5 phenolic hydroxyl groups per oligomeric unit.
Dependencies are inferred from the claim text.