Inductor
An inductor includes a body including a coil and an encapsulant and an external electrode on an outer surface of the body. The encapsulant includes a first core surrounding the coil and a second core surrounding the first core. The first core includes a magnetic powder having high current characteristics, and the second core includes a magnetic powder having high capacity characteristics.
1. An inductor comprising:
a body including a coil and an encapsulant, and having a first surface disposed perpendicularly to a center of a core of the coil and a second surface opposing the first surface; and
an external electrode on an external surface of the body,
wherein the encapsulant includes a first core surrounding the coil and a second core disposed on upper and lower surfaces of the first core,
the first core includes a Fe-based nanocrystalline alloy represented by a compositional formula of (Fe (1-a) M 1 a ) 100-b-c-d-e-f-g M 2 b B c P d Cu e M 3 g , where, M 1 is at least one of cobalt (Co) and nickel (Ni), M 2 is at least one element selected from the group consisting of niobium (Nb), molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W), hafnium (Hf), titanium (Ti), vanadium (V), chromium (Cr) and manganese (Mn), M 3 is at least one element selected from the group consisting of carbon (C), silicon (Si), aluminium (Al), gallium (Ga) and germanium (Ge), and a, b, c, d, e and g of the compositional formula have a content condition of 0≤a≤0.5, 2≤b≤3, 9≤c≤11, 1≤d≤2, 0.6≤e≤1.5 and 9≤g≤11, respectively, based on an atomic %, and
the second core includes a Fe-based alloy represented by a compositional formula of (Fe (1-a) M 1 a ) 100-b-c-d-e-f-g M 2 b B c P d Cu e M 3 g , where, M 1 is at least one of Co and Ni, M 2 is at least one element selected from the group consisting of Nb, Mo, Zr, Ta, W, Hf, Ti, V, Cr and Mn, M 3 is at least two elements selected from a group consisting of C, Si, Al, Ga and Ge, C is an essential element, and a, b, c, d, e and g of the compositional formula have a content condition of 0≤a≤0.5, 1.5≤b≤3, 10≤c≤13, 0≤d≤4, 0≤e≤1.5 and 8.5≤g≤12, respectively, based on an atomic %.
2. The inductor according to claim 1 , wherein in the Fe-based alloy of the second core, a ratio of C content as compared to Fe+C content, based on a weight ratio is over 0.1 and less than 0.7.
3. The inductor according to claim 1 , wherein the first core includes a first inner core disposed inside the innermost coil pattern of the coil and a first outer core surrounding an upper surface of the coil, a lower surface of the coil, and the outermost coil pattern of the coil.
4. The inductor according to claim 3 , wherein the shortest distance from the first surface of the body to the first inner core is substantially equal in length to the shortest distance from the second surface of the body to the first inner core.
5. The inductor according to claim 3 , wherein the shortest distance from the first surface of the body to the first outer core is substantially equal in length to the shortest distance from the second surface of the body to the first outer core.
6. The inductor according to claim 3 , wherein the shortest distance from the first surface of the body to the first inner core is larger than the shortest distance from the first surface of the body to the first outer core.
7. The inductor according to claim 1 , wherein a magnetic saturation Ms of a magnetic powder included in the first core is smaller than a magnetic saturation Ms of a magnetic powder included in the second core.
8. The inductor according to claim 7 , wherein the magnetic saturation Ms of the magnetic powder included in the first core is 120 emu/g or more and 160 emu/g or less, and the magnetic saturation Ms of the magnetic powder included in the second core is larger than 160 emu/g.
9. The inductor according to claim 1 , wherein a coercive force Hc of a magnetic powder included in the first core is 20 A/m or less.
10. The inductor according to claim 1 , wherein a coercive force Hc of a magnetic powder included in the second core is 100 A/m or more.
11. The inductor according to claim 1 , wherein a parent phase of the Fe-based nanocrystalline alloy included in the first core has an amorphous single-phase structure.
12. The inductor according to claim 1 , wherein the first core surrounds the coil in a dumbbell shape.
13. The inductor according to claim 1 , wherein the first core is vertically symmetrical based on a core magnetic flux of the coil.
14. The inductor according to claim 1 , wherein the first core is horizontally symmetrical based on a line perpendicular to a core magnetic flux of the coil.
15. The inductor according to claim 1 , wherein the coil is insulated from an encapsulant, by being surrounded by an insulating layer.
16. The inductor according to claim 1 , wherein the body further includes a support member, and the support member includes a through-hole disposed on a center thereof.
17. An inductor comprising:
a body including a coil and an encapsulant, and having a first surface disposed perpendicularly to a center of a core of the coil and a second surface opposing the first surface; and
an external electrode on an external surface of the body,
wherein the encapsulant includes a first core surrounding the coil and a second core disposed on upper and lower surfaces of the first core,
the first and second cores each include a magnetic material, each magnetic material of the first and second cores including common materials in terms of an alloy, but being composed of different compositions and contents, and
each of the first and second cores is symmetrical on a horizontal basis and a vertical basis with respect to the center of the core of the coil, and not mixed with each other,
the first core includes a Fe-based nanocrystalline alloy represented by a compositional formula of (Fe (1-a) M 1 a ) 100-b-c-d-e-f-g M 2 b B c P d Cu e M 3 g , where, M 1 is at least one of cobalt (Co) and nickel (Ni), M 2 is at least one element selected from the group consisting of niobium (Nb), molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W), hafnium (Hf), titanium (Ti), vanadium (V), chromium (Cr) and manganese (Mn), M 3 is at least one element selected from the group consisting of carbon (C), silicon (Si), aluminium (Al), gallium (Ga) and germanium (Ge), and a, b, c, d, e and g of the compositional formula have a content condition of 0≤a≤0.5, 2≤b≤3, 9≤c≤11, 1≤d≤2, 0.6≤e≤1.5 and 9≤g≤11, respectively, based on an atomic %, and
the second core includes a Fe-based alloy represented by a compositional formula of (Fe (1-a) M 1 a ) 100-b-c-d-e-f-g M 2 b B c P d Cu e M 3 g , where, M 1 is at least one of Co and Ni, M 2 is at least one element selected from the group consisting of Nb, Mo, Zr, Ta, W, Hf, Ti, V, Cr and Mn, M 3 is at least two elements selected from a group consisting of C, Si, Al, Ga and Ge, C is an essential element, and a, b, c, d, e and g of the compositional formula have a content condition of 0≤a≤0.5, 1.5≤b≤3, 10≤c≤13, 0≤d≤4, 0≤e≤1.5 and 8.5≤g≤12, respectively, based on an atomic %.