Ferrite substrates for high-frequency switching DC-to-DC converter applications

A hybrid IC of small capacity DC-to-DC converter was formed on a ferrite substrate which also serves as a core for inductors. The converter has characteristics of 80% in efficiency, 1.2 W/cm
³
in output power and a switching frequency of 500 kHz. To optimize both the magnetic property and mechanical strength of the substrate, a Ni-Cu-Zn ferrite was employed and LiO
2
and WO
3
were added to improve high mechanical strength.