A circuitized substrate including a composite layer including a first dielectric sub-layer including a plurality of fibers having a low coefficient of thermal expansion and a second dielectric sub-layer of a low moisture absorptivity resin, the second dielectric sub-layer not including continuous or semi-continuous fibers or the like as part thereof. The substrate further includes at least one electrically conductive layer as part thereof. An electrical assembly and a method of making the substrate are also provided, as is an information handling system (e.g., computer) incorporating the circuitized substrate of the invention as part thereof.