Molded electrical device

Claim 1

A molded electrical device comprising an electrical circuit element encapsulated in a body of cured insulating material and having at least one conductor for connection to an external circuit, said cured insulating material being the cured product of a molding composition comprising an epoxidized novolac prepolymer I, a novolac II, a catalyst selected and in a quantity effective to catalyze the polymerization of I and cross linking with II, said catalyst being also selected so as not to confer electrically conductive properties on the cured material, and an amount not less than about 50% by weight of the composition of a surface-treated fused silica, said prepolymer I having the formula ##SPC3## wherein m and n are small whole numbers greater than zero and wherein all or substantially all of the phenolic hydrogens are substituted by a group ##EQU10## and said prepolymer II having the formula ##SPC4## wherein a is a small whole number greater than zero, said prepolymers being present in a ratio between about stoichiometric and about 40% molar excess of I, said fused silica filler being a finely ground fused silica the surface of which is modified by surface treatment with a silazane to render the silica particles substantially free from adsorbed moisture and free silanol groups and such that the silica is not wetted by water.