Patent ID: 8257820

Claim:
A circuit subassembly, comprising a conductive layer; a dielectric layer formed from a thermosetting composition, wherein the thermosetting composition comprises, based on the total weight of the thermosetting composition: a polybutadiene or polyisoprene resin, about 30 to about 70 percent by weight of a magnesium hydroxide having less than about 1000 ppm of ionic contaminants, and about 5 to about 15 percent by weight of a nitrogen-containing compound, wherein the nitrogen-containing compound comprises at least about 15 weight percent of nitrogen and is selected from the group consisting of cyanurates, isocyanurates, melamine phosphate, melamine pyrophosphate, and melamine polyphosphate and adducts of triazine compounds with cyanuric acid and isocyanuric acid; and wherein the circuit subassembly has a UL-94 rating of at least V-1, a combined bromine and chlorine content of less than about 900 ppm; and at least one of a water absorption of less than 0.5 percent after submersion in water at 23° C. for 24 hours; a xylene absorption of less than 2% by weight, after a test sample having dimensions of 2 inches×2 inches×20 mils is submerged in xylene at 23° C. for 24 hours; and an acid weight loss less of than 1.0% after submersion in 10 wt. % sulfuric acid at 70° C. for 20 minutes.