Common mode choke coil
In a common mode choke coil having a magnetic core, a decrease in peak value of a common mode impedance in a vicinity of its resonance frequency is suppressed. A common mode choke coil includes a non-magnetic layer, a first magnetic layer formed on a top surface of the non-magnetic layer, a second magnetic layer formed on a bottom surface of the non-magnetic layer, a magnetic core provided between the first magnetic layer and the second magnetic layer so that its axis extends in a top-bottom direction, a first coil conductor embedded in the non-magnetic layer and wound around the magnetic core, a second coil conductor embedded in the non-magnetic layer and wound around the magnetic core, and a first magnetic gap provided between a top surface of the magnetic core and a bottom surface of the first magnetic layer. The magnetic core is made of a ferrite material.
1. A common mode choke coil, comprising:
a non-magnetic layer;
a first magnetic layer formed on a top surface of the non-magnetic layer;
a second magnetic layer formed on a bottom surface of the non-magnetic layer;
a magnetic core provided between the first magnetic layer and the second magnetic layer so that an axis thereof extends in a top-bottom direction;
a first coil conductor embedded in the non-magnetic layer and wound around the magnetic core;
a second coil conductor embedded in the non-magnetic layer and wound around the magnetic core; and
a first magnetic gap provided between either a top surface of the magnetic core and a bottom surface of the first magnetic layer or a bottom surface of the magnetic core and a top surface of the second magnetic layer,
wherein the non-magnetic layer is arranged in direct contact with the first magnetic layer and the second magnetic layer.
2. The common mode choke coil according to claim 1 , wherein the magnetic core is configured so that the top surface thereof has an area equal to or larger than a cross-sectional area of the magnetic core in a direction perpendicular to the axis.
3. The common mode choke coil according to claim 1 ,
wherein the magnetic core has a first portion and a second portion separated from each other in a direction along the axis, and
wherein the common mode choke coil further comprises a second magnetic gap made of a non-magnetic material, the second magnetic gap being provided between the first portion and the second portion, and
the second magnetic gap is formed so that a thickness thereof in the top-bottom direction is smaller than a thickness of the first magnetic gap in the top-bottom direction.
4. The common mode choke coil according to claim 1 , wherein the first coil conductor is disposed more closely to the first magnetic layer than the second coil conductor, and
the first magnetic gap has a thickness in the top-bottom direction smaller than a distance between a top surface of the first coil conductor and the first magnetic layer.
5. The common mode choke coil according to claim 1 , wherein a ratio of a thickness of the first magnetic gap in the top-bottom direction to a distance between the bottom surface of the first magnetic layer and a top surface of the second magnetic layer is smaller than 0.1.
6. The common mode choke coil according to claim 3 , wherein a ratio of a sum of a thickness of the first magnetic gap in the top-bottom direction and a thickness of the second magnetic gap in the top-bottom direction to a distance between the bottom surface of the first magnetic layer and a top surface of the second magnetic layer is smaller than 0.1.
7. The common mode choke coil according to claim 1 , wherein the magnetic core comprises a ferrite material.
8. The common mode choke coil according to claim 1 , wherein the second magnetic layer has a concave portion formed on a top surface thereof, and wherein a portion of the magnetic core is provided in the concave portion.
9. The common mode choke coil according to claim 8 , wherein the concave portion has an arc-shaped cross section.
10. The common mode choke coil according to claim 8 , wherein the magnetic core has a protruding portion that protrudes downward from a bottom surface of the non-magnetic layer and into the concave portion.
11. The common mode choke coil according to claim 8 , wherein a bottom end surface of the magnetic core has an area that is larger than a cross-sectional area of a portion of the magnetic core other than the bottom end surface.
12. A common mode choke coil, comprising:
a non-magnetic layer;
a first magnetic layer formed on a top surface of the non-magnetic layer;
a second magnetic layer formed on a bottom surface of the non-magnetic layer;
a magnetic core provided between the first magnetic layer and the second magnetic layer so that an axis thereof extends in a top-bottom direction;
a first coil conductor embedded in the non-magnetic layer and wound around the magnetic core;
a second coil conductor embedded in the non-magnetic layer and wound around the magnetic core; and
a first magnetic gap provided between a bottom surface of the magnetic core and a top surface of the second magnetic layer,
wherein the non-magnetic layer has a penetration hole therein and wherein the non-magnetic layer is arranged in direct contact with the first magnetic layer and the second magnetic layer,
wherein the second magnetic layer has a concave portion formed on the top surface thereof, and
wherein the magnetic core is provided in the penetration hole and wherein a portion of the magnetic core is provided in the concave portion.
13. The common mode choke coil according to claim 12 , wherein the concave portion has an arc-shaped cross section.
14. The common mode choke coil according to claim 12 , wherein the magnetic core has a protruding portion that protrudes downward from a bottom surface of the non-magnetic layer and into the concave portion.
15. The common mode choke coil according to claim 12 , wherein a bottom end surface of the magnetic core has an area that is larger than a cross-sectional area of a portion of the magnetic core other than the bottom end surface.
16. The common mode choke coil according to claim 1 , wherein the first magnetic gap is an air gap.