# US 2018/0025822 A1 · Soft magnetic metal dust core and reactor having thereof

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- Number: US 2018/0025822 A1
- Document ID: US20180025822A1
- Status: Published application
- Kind: A1
- Application number: 15/656,242
- Filed: 2017-07-21
- Published: 2018-01-25
- Earliest claimed: 2016-07-25
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Yu YONEZAWA; Tomofumi KURODA; Yusuke TANIGUCHI
- Web page: https://patentgrep.com/patent/US20180025822A1

## CPC

- C22C 38/001: {containing N}
- B22F 1/052: characterised by a mixture of particles of different sizes or by the particle size distribution
- B22F 1/065: Spherical particles
- B22F 1/102: Metallic powder coated with organic material
- B22F 1/16: Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10)
- C22C 33/02: by powder metallurgy
- C22C 33/0292: {with more than 5% preformed carbides, nitrides or borides}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/02: containing silicon
- H01F 1/20: in the form of particles, e.g. powder (H01F1/147 takes precedence)
- H01F 1/26: by macromolecular organic substances
- B22F 3/02: Compacting only
- B22F 9/04: starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C)
- B22F 2009/044: {by jet milling}
- C22C 2202/02: Magnetic
- 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)}
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A soft magnetic metal dust core including a soft magnetic metal powder and a nonmagnetic material, in which when observing a field of view including “n”, a natural number of 50 or more, particles of the soft magnetic metal powder on a grinded smooth cross section of the dust core, the soft magnetic metal powder is coated by the nonmagnetic material, and a number of an opposing part P is n/2 or more, in which the opposing part P is a part where a length L is 10 μm or more, and the length L is a continuous length where a distance between particles of the soft magnetic metal powder is 400 nm or less, is provided. The soft magnetic metal dust core is superior in DC superimposing characteristic.

## Claims

### Claim 1

A soft magnetic metal dust core comprising a soft magnetic metal powder and a nonmagnetic material, wherein
when observing a field of view including “n”, a natural number of 50 or more, particles of the soft magnetic metal powder on a grinded smooth cross section of the dust core,
the soft magnetic metal powder is coated by the nonmagnetic material, and
a number of an opposing part P is n/2 or more, wherein
the opposing part P is a part where a length L is 10 μm or more, and
the length L is a continuous length where a distance between particles of the soft magnetic metal powder is 400 nm or less.

### Claim 2 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein
when observing the field of view on the smooth cross section,
a circularity of a cross section of 80% or more particles of the soft magnetic metal powder is 0.75 or more and 1.00 or less.

### Claim 3 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein
when observing the field of view on the smooth cross section,
68% or more of the opposing part P show that a closest distance X is 50 nm or more, wherein
the closest distance X is the shortest distance among the distances between particles at the opposing part P.

### Claim 4 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein
when observing the field of view on the smooth cross section,
an occupancy area ratio of the soft magnetic metal powder to the field of view is 90% or more and 95% or less.

### Claim 5 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein
the nonmagnetic material includes Silicon (Si) and Oxygen (O).

### Claim 6 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein
the nonmagnetic material includes boron nitride, and includes 0.80 mass % or less of Boron (B) and 1.00 mass % or less of Nitrogen (N), with respect to the soft magnetic metal dust core.

### Claim 7 (depends on 1)

The soft magnetic metal dust core according to claim 1, wherein, according to a particle size distribution of the soft magnetic metal powder,
d50% is 20 μm or more and 70 μm or less,
when d50% is a particle diameter of a 50% particle, obtained by accumulating particle numbers from smaller size.

### Claim 8 (depends on 1)

A reactor having the soft magnetic metal dust core according to claim 1.