In one embodiment, an integrated circuit package substrate includes a core layer comprising a plurality of metal vias electrically coupling a first side of the core layer and a second side of the core layer opposite the first side. The package substrate further includes a build-up layer on the first side of the core layer, the build-up layer comprising metal vias within a dielectric material and electrically connected to the metal vias of the core layer. The dielectric material includes Silicon, Oxygen, and at least one of Boron or Phosphorus.