Power core for use in circuitized substrate and method of making same

A power core adapted for use as part of a circuitized substrate, e.g., a PCB or LCC. The core includes a first layer of low expansion dielectric and two added layers of a different low expansion dielectric bonded thereto, with two conductive layers positioned on the two added low expansion dielectric layers. At least one of the conductive layers serves as a power plane for the power core, which in turn is usable within a circuitized substrate, also provided. Methods of making the power core and circuitized substrate are also provided. The use of different low expansion dielectric materials for the power core enables the use of support enhancing fiberglass in one layer while such use is precluded in the other two dielectric layers, thus preventing CAF shorting problems in highly precisely defined thru holes formed within the power core.