| abstract |
The invention is a formulation that contains: (1) a low-viscosity epoxy resin; (2) a phenolic chain extender whose concentration is less that 0.6 equivalents phenolic hydroxyl group per equivalent of the low-viscosity epoxy resin; (3) a catalyst that promotes self-curing reactions between epoxy groups; (4) an inhibitor that inhibits the activity of the catalyst under “B-staging” conditions; (5) less than 25 weight percent of a volatile organic solvent; and (6) optionally, a multifunctional cross-linking agent. The formulation contains low levels of volatile organic solvent, and can be used to make electrical laminates. It builds molecular weight controllably in B-staging, so that dripping is avoided but the prepreg can be easily laminated. |