Dendrimer/hyperbranched materials are combined with polyimide to form a low CTE material for use as a dielectric substrate layer or an underfill. In the alternative, ruthenium carbene complexes are used to catalyze ROMP cross-linking reactions in polyimides to produce a class of cross-linkable, thermal and mechanical stable material for use as a dielectric substrate or underfill. In another alternative, dendrimers/hyperbranched materials are synthesized by different methods to produce low viscosity, high Tg, fast curing, mechanically and chemically stable materials for imprinting applications.