A structure includes a first layer having inductor windings. An inner area of the first layer is at least partially enclosed by the inductor windings and an outer area of the first layer is separated from the inner area by the inductor windings. This structure further includes a second layer having structural fill elements. The first layer and the second layer are parallel, and the second layer is relatively below the first layer in a direction perpendicular to the first layer. The density of the structural fill elements aligned below the inner area is less than the density of the structural fill elements aligned below the outer area.