Soft magnetic powder, method of manufacturing the same, noise suppression sheet using the same, and method of manufacturing the same

1. A noise suppression sheet formed of a composite magnetic body comprising a flat magnetic powder having a saturation magnetostriction of 12.0×10 −6 or more and 38.0×10 −6 or less and an organic binder, the flat magnetic powder being obtained by heat-treating a flat Fe-based amorphous alloy powder having an amorphous phase, the flat magnetic powder having the amorphous phase at least at one part of the flat magnetic powder, and not having a compound crystalline phase precipitated in the flat magnetic powder, excluding an α-Fe crystalline phase;

wherein the flat Fe-based amorphous alloy powder contains a soft magnetic metal material;

wherein the flat magnetic powder has two phases consisting of the amorphous phase and a crystalline phase consisting of the α-Fe crystalline phase; and

wherein the flat Fe-based amorphous alloy powder is a powder of a Fe—Si—B—P—Cr amorphous alloy, and said alloy containing 76 to 80 at % of Fe.

2. The noise suppression sheet according to claim 1 , wherein the flat magnetic powder has a saturation magnetostriction of 12.1×10 −6 or more and 30.6×10 −6 or less.

3. The noise suppression sheet according to claim 1 , wherein the flat magnetic powder has an average particle size (D 50 ) of 50 μm or more and 127 μm or less.

4. The noise suppression sheet according to claim 1 , wherein the noise suppression sheet has an imaginary part magnetic permeability μ″ of 8.3 or more and 15.4 or less at 2.45 GHz.

5. A method of manufacturing a noise suppression sheet comprising forming, into a sheet shape, a composite magnetic body in which an organic binder is mixed into a flat magnetic powder having a saturation magnetostriction of 12.0×10 −6 or more and 38.0×10 −6 or less, the flat magnetic powder being obtained by heat-treating a flat Fe-based amorphous alloy powder having an amorphous phase, the flat magnetic powder having the amorphous phase at least at one part of the flat magnetic powder, and not having a compound crystalline phase precipitated in the flat magnetic powder, excluding an α-Fe crystalline phase;

wherein the flat Fe-based amorphous alloy powder contains a soft magnetic metal material;

wherein the flat magnetic powder has two phases consisting of the amorphous phase and a crystalline phase consisting of the α-Fe crystalline phase; and

wherein the flat Fe-based amorphous alloy powder is a powder of a Fe—Si—B—P—Cr amorphous alloy, and said alloy containing 76 to 80 at % of Fe.

6. The method of manufacturing a noise suppression sheet according to claim 5 , wherein the flat magnetic powder has a saturation magnetostriction of 12.1×10 −6 or more and 30.6×10 −6 or less.

7. The method of manufacturing a noise suppression sheet according to claim 5 , wherein the flat magnetic powder has an average particle size (D 50 ) of 50 μm or more and 127 μm or less.

8. The method of manufacturing a noise suppression sheet according to claim 5 , wherein the noise suppression sheet has an imaginary part magnetic permeability μ″ of 8.3 or more and 15.4 or less at 2.45 GHz.

9. A flat magnetic powder having a saturation magnetostriction of 12.0×10 −6 or more and 38.0×10 −6 or less and having a flat shape, the flat magnetic powder being obtained by heat-treating a flat Fe-based amorphous alloy powder having an amorphous phase, the flat magnetic powder having the amorphous phase at least at one part of the flat magnetic powder, and not having a compound crystalline phase precipitated in the flat magnetic powder, excluding an α-Fe crystalline phase;

wherein the flat Fe-based amorphous alloy powder contains a soft magnetic metal material;

wherein the flat magnetic powder has two phases consisting of an amorphous phase and a crystalline phase consisting of the α-Fe crystalline phase; and

wherein the flat Fe-based amorphous alloy powder is a powder of a Fe—Si—B—P—Cr amorphous alloy, and said alloy containing 76 top 80 at % of Fe.

10. The flat magnetic powder according to claim 9 , wherein the flat magnetic powder has a saturation magnetostriction of 12.1×10 −6 or more and 30.6×10 −6 or less.

11. The flat magnetic powder according to claim 9 , wherein the flat magnetic powder has an average particle size (D 50 ) of 50 μm or more and 127 μm or less.

12. A method of manufacturing the flat magnetic powder claimed in claim 9 , the method comprising:

(a) forming a Fe-based amorphous alloy powder from the soft magnetic metal material by an atomizing method,

(b) grinding the Fe-based amorphous alloy powder from step (a) to form it into the flat Fe-based amorphous alloy powder,

(c) heat-treating the flat Fe-based amorphous alloy powder from step (b) to obtain the flat magnetic powder, which is a flat shape soft magnetic metal powder having a saturation magnetostriction of 12.0×10 −6 or more and 38.0×10 −6 or less;

wherein the flat magnetic powder has two phases consisting of an amorphous phase and a crystalline phase consisting of the α-Fe crystalline phase; and

wherein the flat Fe-based amorphous alloy powder is a powder of a Fe—Si—B—P—Cr amorphous alloy, said alloy containing 76 to 80 at % of Fe.

13. The method of manufacturing a flat magnetic powder according to claim 12 , wherein the heat-treating step (c) is carried out by heating the flat Fe-based amorphous alloy powder at a temperature lower than a crystallization temperature to precipitate said crystalline phase consisting of the α-Fe crystalline phase, in an Fe amorphous phase.

14. The method of manufacturing a flat magnetic powder according to claim 12 , wherein the flat magnetic powder has an average particle size (D 50 ) of 50 μm or more and 127 μm or less.