A vacuum cast or “solid” transformer coil assembly and a method of manufacturing thereof are provided. A solid transformer coil assembly, according to an embodiment of the invention, includes a dielectric substrate, the coil windings provided around the substrate, and an epoxy compound encapsulating the substrate and the coil windings. The substrate is provided with raised “buttons” comprising the same epoxy material as the epoxy compound used for encapsulation. The buttons maintain a specific distance between the coil and the dielectric substrate. The buttons are arranged such that they support the windings and allow the encapsulating epoxy to flow around them flooding the entire mold without entrapping air or creating voids.