A composition and process to make polyisocyanurate or polyurethane foam using a catalyst composition comprising at least one bismuth carboxylate catalyst and one or more co-catalysts selected from the group of alkali metal carboxylates and quaternary ammonium carboxylate salts, such that the resultant foam has improved insulation properties. The mentioned material is laid on the substrate as a layer in a thickness corresponding to one of the overall size values of any one of the magnetic segment being formed. In this embodiment, a desired performance value indicative of a user’s desired performance level for an electrical device is received.