Coil component and fabrication method of the same

1. A coil component comprising:

a coil-containing insulator enclosure obtained by enclosing a coil, except for end portions of the coil, with an insulator which comprises a first resin; and

a magnetic core made of a mixture of a second resin and a powder, the powder comprises magnetic powder having particles, wherein at least one part of the coil-containing insulator enclosure is embedded in the magnetic core, the coil comprising a plurality of turns of a conductor, the turns being stacked along a predetermined direction with each space between neighboring turns being filled with the insulator,

wherein the insulator has a first thickness in a radial direction of the coil and a second thickness in an axial direction of the coil; and each of the first and the second thicknesses is larger than one-third of an average particle size of the magnetic powder, the insulator further comprises a non-magnetic filler added to the first resin, the coil comprising two coil members each having an axis, the coil members being arranged so that the axes of the coil members are parallel to each other, the insulator comprising a connection portion between the coil members, the connection portion having a third thickness between the coil members in a first direction perpendicular to the axial direction, the connection portion having a fourth thickness in a second direction perpendicular to the axial direction and the first direction, the fourth thickness being equal to or more than the third thickness, the third thickness being one-third or more of an average particle size of the non-magnetic filler.

2. The coil component according to claim 1 , wherein the coil-containing insulator enclosure is completely embedded in the magnetic core made of the mixture, except for the end portions of the coil.

3. The coil component according to claim 1 , wherein the coil-containing insulator enclosure is an insulator casting obtained by casting material of the insulator.

4. The coil component according to claim 1 , wherein the insulator comprises:

a bobbin which has, on a peripheral part thereof, a groove, wherein the coil is wound on the peripheral part of the bobbin to be held in the groove; and

a cover which covers the peripheral part of the bobbin, wherein the coil is accommodated in a space formed between the groove and the cover.

5. The coil component according to claim 1 , wherein the first resin and the second resin are one and the same kind of a curable or hardenable resin.

6. The coil component according to claim 1 , wherein each of the first resin and the second resin is a thermosettable resin.

7. The coil component according to claim 1 , wherein each of the particles of the magnetic powder is provided with a high permeability thin layer, which is formed on a surface of each particle of the magnetic powder.

8. The coil component according to claim 1 , wherein each of the particles of the magnetic powder is coated with at least one insulator layer in advance of forming the mixture of the powder and the second resin.

9. The coil component according to claim 1 , wherein a mixing ratio of the second resin in the mixture is in a range of from 20 percent by volume, to 90 percent, by volume, both inclusive.

10. The coil component according to claim 9 , wherein the mixing ratio is in a range of from 40 percent, by volume, to 70 percent, by volume, both inclusive.

11. The coil component according to claim 1 , wherein the second resin is an epoxy resin or a silicone resin.

12. The coil component according to claim 1 , wherein the first resin is an epoxy resin or a silicone resin.

13. The coil component according to claim 1 , wherein the magnetic powder is soft magnetic powder.

14. The coil component according to claim 13 , wherein the soft magnetic powder is soft magnetic metal powder.

15. The coil component according to claim 14 , wherein the soft magnetic metal powder is Fe—Si system powder.

16. The coil component according to claim 15 , wherein an average content of Si in the Fe—Si system powder is in a range of from 0.0 percent, by weight, to 11.0 percent, by weight, both inclusive.

17. The coil component according to claim 14 , wherein the soft magnetic metal powder is Fe—Si—Al system powder.

18. The coil component according to claim 17 , wherein an average content of Si in the Fe—Si—Al system powder is in a range of from 0.0 percent, by weight, to 11.0 percent, by weight, both inclusive, and an average content of Al in the Fe—Si—Al system powder is in a range of from 0.0 percent, by weight, to 7.0 percent, by weight, both inclusive.

19. The coil component according to claim 14 , wherein the soft magnetic metal powder is Fe—Ni system powder.

20. The coil component according to claim 19 , wherein an average content of Ni in the Fe—Ni system powder is in a range of from 30.0 percent, by weight, to 85.0 percent, by weight, both inclusive.

21. The coil component according to claim 14 , wherein the soft magnetic metal powder is Fe system amorphous powder.

22. The coil component according to claim 1 , wherein the mixture includes a non-magnetic filler.

23. The coil component according to claim 1 , wherein the magnetic core made of the mixture has a relative permeability of 10 or more in a magnetic field of 1000*10 3 /4π[A/m].

24. The coil component according to claim 1 , wherein the insulator further comprises a non-magnetic filler added to the first resin; and wherein:

the non-magnetic filler is selected from the group consisting of a glass fiber, a granular resin and an inorganic material base powder, said inorganic material base powder being selected from the group consisting of alumina powder, titanium oxide powder, zirconium powder, calcium carbonate powder and aluminum hydroxide powder.

25. The coil component according to claim 24 , wherein the non-magnetic filler is such that a linear expansion coefficient of the mixture when hardened corresponds to that of the insulator when hardened.

26. The coil component according to claim 24 , wherein the non-magnetic filler is such that an elastic modulus of the mixture when hardened corresponds to that of the insulator when hardened.

27. The coil component according to claim 24 , wherein the non-magnetic filler is substantially spherical powder.

28. The coil component according to claim 27 , wherein the insulator has a first thickness in a radial direction of the coil and a second thickness in an axial direction of the coil; each of the first and the second thicknesses is larger than one-third of an average particle size of the magnetic powder; and each of the first and the second thicknesses is larger than one-third of an average particle size of the non-magnetic filler.

29. The coil component according to claim 24 , wherein a ratio of the first resin in the insulator including the non-magnetic filler is in a range of 30 or more percent, by volume.

30. The coil component according to claim 1 , wherein the coil-containing insulator enclosure has a hollow portion surrounded by the coil.

31. The coil component according to claim 30 , further comprising a specific magnetic core member disposed around the coil-containing insulator enclosure and/or within the hollow portion of the coil-containing insulator enclosure, wherein the specific magnetic core member is fixed to the coil-containing insulator enclosure by means of the magnetic core made of the mixture.

32. The coil component according to claim 31 , wherein the specific magnetic core member is a dust core made of powder selected from the group consisting of Fe system amorphous powder, Fe—Si system powder, Fe—Si—Al system powder and Fe—Ni system powder, or a laminated core made of Fe base thin sheets.

33. The coil component according to claim 30 , further comprising a high magnetic reluctance member, which has a magnetic reluctance higher than the mixture and is embedded in the magnetic core made of the mixture.

34. The coil component according to claim 33 , wherein the high magnetic reluctance member is made of a material comprising the same resin as the first resin.

35. The coil component according to claim 34 , wherein the high magnetic reluctance member is made of the same material as the insulator.

36. The coil component according to claim 33 , wherein the high magnetic reluctance member is placed within the hollow portion.

37. The coil component according to claim 36 , comprising at least two of the high magnetic reluctance members, wherein the high magnetic reluctance members are arranged parallel to each other.

38. The coil component according to claim 36 , wherein the high magnetic reluctance member has a shape in which a peripheral part of the high magnetic reluctance member is larger in thickness than a central part of the high magnetic reluctance member.

39. The coil component according to claim 33 , wherein the high magnetic reluctance member constitutes a region which has a relative permeability of 20 or less within the magnetic core made of the mixture.

40. The coil component according to claim 30 , wherein the magnetic core made of the mixture constitutes a loop of a magnetic path passing a center of the coil.

41. The coil component according to claim 1 , wherein: the coil has a specific structure where at least two coil members are arranged so that axial directions of the coil members are parallel to each other and where neighboring ones of the coil members are connected to each other to form one magnetic path; and, between the neighboring ones of the coil members, there is formed a high magnetic resistance region which extends in a direction parallel to the axial directions of the coil members.

42. The coil component according to claim 41 , wherein the high magnetic resistance region has a relative permeability of 20 or less.

43. The coil component according to claim 41 , wherein the high magnetic resistance region is made of a material comprising the same resin as the first resin.

44. The coil component according to claim 43 , wherein the high magnetic resistance region is made of the same material as the insulator.

45. The coil component according to claim 1 , further comprising a case, wherein the coil-containing insulator enclosure is arranged within the case, and the magnetic core made of the mixture is filled between the coil-containing insulator enclosure and the case and encapsulates the coil-containing insulator enclosure therein.

46. The coil component according to claim 45 , wherein the case comprises a metal container and an insulator layer formed on an inner surface of the metal container, or wherein the case comprises a ceramic container.

47. The coil component according to claim 46 , wherein the metal container is made of aluminum or Fe—Ni alloy, or wherein the ceramic container is an alumina mold.

48. The coil component according to claim 1 , wherein the magnetic core is a casting obtained by casting the mixture.

49. The coil component according to claim 48 , wherein the mixture comprises materials which are capable of casting without any solvents.

50. A method of manufacturing a coil component according to claim 1 , which comprises: a coil-containing insulator enclosure obtainable by enclosing a coil, except for end portions of the coil, with an insulator comprising at least a first resin; and a magnetic core made of a mixture of a second resin and powder comprising magnetic powder, the method comprising the steps of:

forming a mixture spacer from the mixture;

positioning the coil-containing insulator enclosure within a case by the use of the mixture spacer;

casting the mixture into the case; and

hardening the mixture so that the coil-containing insulator enclosure is embedded in the magnetic core made of the mixture.

51. The method according to claim 50 , further comprising the steps of:

forming an insulator spacer from the insulator;

positioning the coil within a temporal container by the use of the insulator spacer;

casting the insulator into the temporal container to enclose the coil, except for the end portions of the coil, with the insulator; and

hardening the insulator to form the coil-containing insulator enclosure.

52. The method according to claim 50 , wherein the coil-containing insulator enclosure has a hollow portion surrounded by the coil, and the method further comprises the steps of:

forming a high magnetic reluctance member from the insulator; and

placing the high magnetic reluctance member within the hollow portion of the coil-containing insulator enclosure during the step of casting the mixture.

53. The coil component according to claim 1 , wherein the magnetic powder is substantially a spherical powder.

54. The coil component according to claim 1 , wherein the coil component is obtained by:

forming a mixture spacer from the mixture;

positioning the coil-containing insulator enclosure within a case by use of the mixture spacer;

casting the mixture into the case; and

hardening the mixture so that the coil-containing insulator enclosure is embedded in the magnetic core made of the mixture.