Composite magnetic body, and magnetic element and method of manufacturing the same

• US 20020097124A1
• Filed: 04/25/2001
• Published: 07/25/2002
• Est. Priority Date: 04/28/2000
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fujii, Hiroshi, Takahashi, Takeshi, Inoue, Osamu, Matsutani, Nobuya, Kato, Junichi
• Granted Patent: US 6,784,782 B2
• Time in Patent Office: Days
• US Class Current: 336/83
• CPC Class Codes: H01F 1/24 the particles being insulated
• CPC Class Codes: H01F 1/26 by macromolecular organic substances
• CPC Class Codes: H01F 1/28 dispersed or suspended in a bonding agent
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 27/027 specially adapted for combination of signal type inductors or transformers with electronic circuits, e.g. mounting on printed circuit boards
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 41/127 Encapsulating or impregnating encapsulating coil and core H01F41/005
• CPC Class Codes: Y10S 156/922 Specified electronic component delaminating in preparation for recycling
• CPC Class Codes: Y10T 156/1082 Partial cutting bonded sandwich [e.g., grooving or incising]
• CPC Class Codes: Y10T 156/11 Methods of delaminating, per se; i.e. , separating at bonding face
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49021 Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core
• CPC Class Codes: Y10T 29/49158 with molding of insulated base
• CPC Class Codes: Y10T 29/49172 by molding of insulating material
• CPC Class Codes: Y10T 29/49176 with molding of electrically insulating material
• CPC Class Codes: Y10T 29/4922 with molding of insulation
• CPC Class Codes: Y10T 29/49261 : by composite casting or molding
• CPC Class Codes: Y10T 29/49277 : including casting or molding
• CPC Class Codes: Y10T 428/11 : Magnetic recording head
• CPC Class Codes: Y10T 428/32 : Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer

Abstract

The present invention provides a composite magnetic body containing metallic magnetic powder and thermosetting resin and having a packing ratio of the metallic magnetic powder of 65 vol % to 90 vol % and an electrical resistivity of at least 10⁴Ω·cm. When a coil is embedded in this composite magnetic body, a miniature magnetic element can be obtained that has a high inductance value and is excellent in DC bias characteristics.

Claims

1. A composite magnetic body, comprising:

metallic magnetic powder; and

thermosetting resin,

wherein the composite magnetic body has a packing ratio of the metallic magnetic powder of 65 vol % to 90 vol % and an electrical resistivity of at least 10⁴Ω

·

cm.

2. The composite magnetic body according to claim 1, wherein the packing ratio of the metallic magnetic powder is 70 vol % to 85 vol %.

3. The composite magnetic body according to claim 1, wherein the metallic magnetic powder contains, as a main component, a magnetic metal selected from Fe, Ni, and Co and, as a subsidiary component, a non-magnetic element in a total amount not exceeding 10 wt %.

4. The composite magnetic body according to claim 1, wherein the metallic magnetic powder contains at least one non-magnetic element selected from Si, Al, Cr, Ti, Zr, Nb, and Ta.

5. The composite magnetic body according to claim 1, further comprising an electrical insulating material other than the thermosetting resin.

6. The composite magnetic body according to claim 5, wherein the electrical insulating material comprises an oxide film formed on a surface of the metallic magnetic powder.

7. The composite magnetic body according to claim 6, wherein the oxide film contains at least one non-magnetic element selected from Si, Al, Cr, Ti, Zr, Nb, and Ta.

8. The composite magnetic body according to claim 7, wherein the oxide film has a thickness of 10 nm to 500 nm.

9. The composite magnetic body according to claim 5, wherein the electrical insulating material contains at least one selected from an organic silicon compound, an organic titanium compound, and a silica-based compound.

10. The composite magnetic body according to claim 5, wherein the electrical insulating material is a solid powder with a mean particle size not exceeding one tenth of that of the metallic magnetic powder.

11. The composite magnetic body according to claim 5, wherein the electrical insulating material is plate- or needle-like particles.

12. The composite magnetic body according to claim 11, wherein the plate- or needle-like particles have an aspect ratio of at least 3/1.

13. The composite magnetic body according to claim 11, wherein the plate- or needle-like particles have a mean largest-diameter of 0.2 to 3 times a mean particle size of the metallic magnetic powder.

14. The composite magnetic body according to claim 11, wherein the plate- or needle-like particles contain at least one selected from talc, boron nitride, zinc oxide, titanium oxide, silicon oxide, aluminum oxide, iron oxide, barium sulfate, and mica.

15. The composite magnetic body according to claim 5, wherein the electrical insulating material is at least one selected from fatty acid salt, fluororesin, talc, and boron nitride.

17. The magnetic element according to claim 16, further comprising a second magnetic body when the composite magnetic body is defined as a first magnetic body,

wherein the second magnetic body has a higher magnetic permeability than that of the first magnetic body.

18. The magnetic element according to claim 17, wherein the coil and the second magnetic body are disposed so that a closed path passing through inner and outer sides of the coil via the second magnetic body alone is not formed.

19. The magnetic element according to claim 17, wherein the second magnetic body is at least one selected from ferrite and a dust core.

16. A magnetic element, comprising:

a composite magnetic body comprising metallic magnetic powder and thermosetting resin and having a packing ratio of the metallic magnetic powder of 65 vol % to 90 vol % and an electrical resistivity of at least 10⁴Ω

·

cm; and

a coil embedded in the composite magnetic body.

20. A method of manufacturing a magnetic element comprising a composite magnetic body containing metallic magnetic powder and thermosetting resin and having a packing ratio of the metallic magnetic powder of 65 vol % to 90 vol % and an electrical resistivity of at least 10⁴Ω

·

cm, and a coil embedded in the composite magnetic body, the method comprising;

obtaining a mixture including metallic magnetic powder and thermosetting resin present in an uncured state;

obtaining a molded body by pressure-molding the mixture to embed the coil; and

curing the thermosetting resin by heating the molded body.

21. The method of manufacturing a magnetic element according to claim 20, further comprising, before curing the thermosetting resin, heating the mixture containing the metallic magnetic powder and the thermosetting resin present in the uncured state in a range between 65°

C. and 200°

C.

22. The method of manufacturing a magnetic element according to claim 20, further comprising granulating the mixture containing the metallic magnetic powder and the thermosetting resin present in the uncured state.

23. The method of manufacturing a magnetic element according to claim 20, wherein the thermosetting resin whose main component in the uncured state is powder at ordinary temperature is mixed, without being dissolved in a solvent, with a remaining portion of the material containing the metallic magnetic powder.

24. The method of manufacturing a magnetic element according to claim 20, wherein the main component of the thermosetting resin is a liquid at ordinary temperature.