Patent ID: 7821371

Claim:
A planar magnetic device comprising: a first magnetic layer, a second magnetic layer, and a planar coil disposed between the first magnetic layer and the second magnetic layer, wherein magnetic particles, having a shape ratio S/L of 0.7 to 1 where a length of a long axis is L and a length of a short axis orthogonal to the long axis is S, fill a gap between coil wirings of the planar coil, the gap between the coil wirings of the planar coil being W, where W is 200 μm or less; an average particle diameter of the magnetic particles is W/2 or less; a thickness of the planar magnetic device is 0.5 mm or less; and a filling ratio of the magnetic particles filled in the gap between the coil wirings of the planar coil is 30 vol. % or more.