LAUSR

A significant fraction of the volume of a dc–dc power module is often occupied by the filter inductor and by the molding compound padding the unused space. This letter presents a method to fabricate an inductor in which the core is realized by molding a magnetic mixture over the circuit board. Permeability above 20 was achieved using a curing temperature not exceeding 250 °C, and no applied pressure. A power converter with input of 12 V, output of 1.2 V at 5 A, and switching frequency of 500 kHz was constructed to check the operation with a 1.1-μH over-molded inductor. The over-molded magnetic material did not adversely interfere with converter operation, e.g., switching noise was low. The maximum temperature of 48.3 °C and full-load efficiency of 82% are similar to those of the same circuit using a discrete inductor.