Patent ID: 7192997

Claim:
An encapsulant composition comprising: a resin material selected from the group consisting of epoxy and cyanate ester resins; from about 1.0% by weight to about 5% by weight of the composition of a flexibilizing agent comprising a flexibilizer containing functional groups capable of reaction with the epoxy or cyanate ester resin during thermally induced curing, and a thermoplastic other than the flexibilizer, wherein the thermoplastic is separated from the cured epoxy or cyanate ester resin; and a filler material comprising substantially spherical or spheroidal particles, each particle having a diameter of less than about 41 microns, wherein the composition has a higher fracture toughness, a lower viscosity, and increased thermal shock resistance at a temperature excursion below −40° C., or combinations thereof than the composition would have if the flexibilizing agent were not present in the composition, wherein the thermoplastic comprises a poly(arylene)ether, and wherein the flexibilizer comprises bis(2,3-epoxy-2-methylpropyl)ether.