Planar magnetic device and power supply IC package using same
View Patent ↗A planar magnetic device 1 includes a first magnetic layer 3 and a second magnetic layer 5 that are made of a mixture of a magnetic powder 7 and a resin, and a planar coil 4 disposed between the magnetic layers. When the planar coil 4 has an adjacent winding interval W between the potions 4 c of the coil and the magnetic powder 7 has a maximum particle size L, planar magnetic device 1 satisfies the relationship W>L. In the planar magnetic device 1 having the above structure, fine magnetic powder that can produce a high inductance fills the spaces between the adjacent windings. Thus, the invention can achieve a high-performance planar magnetic device, such as a thin inductor.
1. 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.
2. The planar magnetic device according to claim 1 , wherein at least five particles of the magnetic powder are disposed in the segment having the length W defined by the adjacent winding interval W.
3. The planar magnetic device according to claim 1 , wherein the magnetic powder contains at least one selected from the group consisting of amorphous alloys, fine crystal alloys, pure iron, sendust, Fe-Ni alloys, Fe-Si alloys, and ferrites.
4. The planar magnetic device according to claim 1 , wherein the magnetic powder has an average particle size of 80 μm or less.
5. The planar magnetic device according to claim 1 , wherein the planar coil is made of a sintered body of metal powder.
6. The planar magnetic device according to claim 1 , wherein the planar coil is formed by etching a metal foil.
7. A power IC package comprising:
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, and
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.
8. The power IC package according to claim 7 , wherein the power IC package is integrated with an IC.
9. The planar magnetic device according to claim 7 , wherein at least five particles of the magnetic powder are disposed in the segment having the length W defined by the adjacent winding interval W.
10. The planar magnetic device according to claim 7 , wherein the magnetic powder contains at least one selected from the group consisting of amorphous alloys, fine crystal alloys, pure iron, sendust, Fe-Ni alloys, Fe-Si alloys, and ferrites.
11. The planar magnetic device according to claim 7 , wherein the magnetic powder has an average particle size of 80 μm or less.
12. The planar magnetic device according to claim 7 , wherein the planar coil is made of a sintered body of metal powder.
13. The planar magnetic device according to claim 7 , wherein the planar coil is formed by etching a metal foil.