Patent ID: 7920043

Claim:
A planar magnetic device comprising: a first magnetic layer and a second magnetic layer that are made of a mixture of a magnetic powder and a resin; and a planar coil disposed between the first magnetic layer and the second magnetic layer, wherein the planar coil and the magnetic powder satisfy the relationship W >2L, where W represents the intervals between adjacent windings of the planar coil and L represents the maximum particle size of the magnetic powder, wherein the intervals W between adjacent windings of the planar coil are filled with the mixture of the magnetic powder and the resin, and the planar magnetic device has a thickness of 0.4 mm or less, wherein at least three particles of the magnetic powder are disposed in a segment having a length w defined by the adjacent winding interval W of the planar coil, and an insulating layer is not formed between the magnetic layers and the planar coil, and wherein the magnetic powder contained in the magnetic layer is close to the planar coil at a distance of 1 μm or less or is in contact with the planar coil, the thickness of the planar coil is 10 to 200 μm, and the interval W is 10 μm or more.