Integrated circuits and processes for manufacturing integrated circuits are described that use printed wiring board substrates (200) having a core layer (10) that is part of the circuit of the printed wiring board. In a number of embodiments, the core layer is constructed from a carbon composite. In several embodiments, techniques are described for increasing the integrity of core layers in designs calling for high density clearance hole (25) drilling. One embodiment of the invention includes a core layer that includes electrically conductive material and at least one build-up wiring portion formed on an outer surface of the core layer. In addition, the build-up portion comprises at least one micro wiring layer (36) including a circuit that is electrically connected to the electrically conductive material in the core layer via a plated through hole (45).