Soft magnetic composite material

• US 6,338,900 B1
• Filed: 08/24/1999
• Issued: 01/15/2002
• Est. Priority Date: 02/13/1997
• Status: Expired due to Fees

• Current Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
• Original Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
• Inventors: Suzuki, Keiichiro, Tada, Masahito
• Primary Examiner(s): Resan, Stevan A.
• Assistant Examiner(s): Bernatz, Kevin M.
• Application Number:
  US09/367,947
• Time in Patent Office: 875 Days
• Field of Search: 428/329, 428/332, 428/694.BS, 428/402, 428/688, 335/281, 335/296, 335/297, 336/233, 752/45, 753/48, 148/306, 252/62-1-
• US Class Current: 428/402
• CPC Class Codes: H01F 1/37 in a bonding agent
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

A soft magnetic composite material obtained by dispersing a powdered magnetic material (A) composed of soft ferrite in a polymer (B), wherein the powdered magnetic material (A) is a powdered magnetic material of a random form obtained by grinding a sintered magnetic material, and the average particle size (d₂) of the powdered magnetic material (A) is greater than the average crystal grain size (d₁) of the sintered magnetic material by at least twice.

Claims

1. A soft magnetic composite material obtained by dispersing a sintered, powdered magnetic material (A) composed of soft ferrite in a polymer (B), wherein the sintered, powdered magnetic material (A) is of a random form, and the average particle size (d₂) of the sintered, powdered magnetic material (A) is greater than the average crystal grain size (d₁) of the sintered, powdered magnetic material by at least twice.

2. The soft magnetic composite material according to claim 1, wherein the powdered magnetic material (A) is a powdered material composed of Mg—

Zn ferrite.

3. The soft magnetic composite material according to claim 1, wherein the powdered magnetic material (A) is a powdered magnetic material of a random form obtained by granulating unsintered ferrite powder into granules by a spray drying method, sintering the granules and grinding the resultant sintered magnetic material.

4. The soft magnetic composite material according to claim 1, wherein the average particle size (d₂) of the powdered magnetic material (A) is within a range of 2 to 10 times the average crystal grain size (d₁) of the sintered magnetic material.

5. The soft magnetic composite material according to claim 4, wherein the average particle size (d₂) of the powdered magnetic material (A) is within a range of 3 to 7 times the average crystal grain size (d₁) of the sintered magnetic material.

6. The soft magnetic composite material according to claim 1, wherein the average crystal grain size (d₁) of the sintered magnetic material is within a range of 2 to 50 μ

m, the average particle size (d₂) of the powdered magnetic material (A) is within a range of 20 to 500 μ

m, the average particle size (d₂) is within a range of 2 to 10 times the average crystal grain size (d₁).

7. The soft magnetic composite material according to claim 6, wherein the average crystal grain size (d₁) of the sintered magnetic material is within a range of 3 to 15 μ

m, the average particle size (d₂) of the powdered magnetic material (A) is within a range of 20 to 50 μ

m, the average particle size (d₂) is within a range of 3 to 7 times the average crystal grain size (d₁).

8. The soft magnetic composite material according to claim 1, which comprises 50 to 95 vol. % of the powdered magnetic material (A) and 5 to 50 vol. % of the polymer (B).

9. The soft magnetic composite material according to claim 8, which comprises 55 to 75 vol. % of the powdered magnetic material (A) and 25 to 45 vol. % of the polymer (B).

10. The soft magnetic composite material according to claim 1, wherein the polymer (B) is at least one polymer selected from the group consisting of polyolefins, polyamides and poly(arylene sulfides).

11. The soft magnetic composite material according to claim 10, wherein the polymer (B) is a poly(arylene sulfide).

12. The soft magnetic composite material according to claim 11, wherein the poly(arylene sulfide) is poly(phenylene sulfide).

13. The soft magnetic composite material according to claim 1, wherein the dielectric strength of the soft magnetic composite material is at least 1,500 V.

14. The soft magnetic composite material according to claim 13, wherein the dielectric strength of the soft magnetic composite material is within a range of 1,500 to 8,000 V.

15. The soft magnetic composite material according to claim 14, wherein the dielectric strength of the soft magnetic composite material is within a range of 3,500 to 6,000 V.

16. The soft magnetic composite material according to claim 1, wherein the relative permeability of the soft magnetic composite material is at least 10.

17. The soft magnetic composite material according to claim 16, wherein the relative permeability of the soft magnetic composite material is within a range of 10 to 20.

18. The soft magnetic composite material according to claim 1, which is obtained by dispersing the powdered magnetic material (A) composed of soft ferrite in the polymer (B), wherein:

(1) the powdered magnetic material (A) is a powdered magnetic material of a random form obtained by grinding a sintered magnetic material,

(2) the average crystal grain size (d₁) of the sintered magnetic material is within a range of 3 to 13 μ

m,

(3) the average particle size (d₂) of the powdered magnetic material (A) is within a range of 20 to 50 μ

m,

(4) the average particle size (d₂) of the powdered magnetic material (A) is within a range of 3 to 7 times the average crystal grain size (d₁),

(5) the soft magnetic composite material comprises 55 to75 vol. % of the powdered magnetic material (A) and 25 to 45 vol. % of the polymer (B),

(6) the dielectric strength of the soft magnetic composite material is within, a range of 1,500 to 8,000 V, and

(7) the relative permeability of the soft magnetic composite material is within a range of 10 to 20.

19. The soft magnetic composite material according to claim 18, wherein the powdered magnetic material (A) is powder of Mg—

Zn ferrite, and the dielectric strength of the soft magnetic composite material is within a range of 3,500 to 6,000 V.

20. The soft magnetic composite material according to claim 18, wherein the polymer (B) is poly(phenylene sulfide).

21. A soft magnetic composite material obtained by dispersing a sintered, powdered magnetic material (A) of a random form and composed of soft ferrite in a polymer (B), wherein:

(1) the sintered, powdered magnetic material (A) is composed of Mg—

Zn ferrite,

(2) the average particle size (d₂) of the sintered, powdered magnetic material (A) is greater than the average crystal grain size (d₁) of the sintered, powdered magnetic material by at least twice,

(3) the soft magnetic composite material comprises 50 to 95 vol. % of the sintered, powdered magnetic material (A) and 5 to 50 vol. % of the polymer (B), and

(4) the dielectric strength of the soft magnetic composite material is at least 1,500 V.