A series of plated through hole (PTH) vias are interconnected by traces
that alternate between a top surface and a bottom surface of a dielectric
board. The PTH vias in the series can be positioned to create a collinear
inductive filter, a coil-type inductive filter, or a transformer.
Multiple, electrically isolated series of interconnected PTH vias can be
used as a multi-phase inductive filter in one embodiment. In another
embodiment, multiple series of interconnected PTH vias are electrically
connected by a linking portion of conductive material, resulting in a
low-resistance inductive filter. Ferromagnetic material patterns can be
embedded in the dielectric board to enhance the inductive characteristics
of the interconnected via structures. In one embodiment, a closed-end
pattern is provided with two series of interconnected vias coiling around
the pattern, resulting in an embedded transformer structure. A method of
producing an interconnected series of PTH vias includes providing a
dielectric board having a series of holes. In some embodiments, the board
includes an embedded ferromagnetic material pattern. The holes and the
top and bottom surface of the dielectric board have a conductive material
thereupon. Portions of the conductive material are selectively removed,
resulting in the embedded inductive filter and/or transformer structure.