Hitachi Powdered Metals Co., Ltd.

Denso Corporation

Kohei Muramatsu

Chio Ishihara

Kazuo Asaka

Tsuyoshi Akao

Hirotake Hamamatsu

Masaki Yanaka

A powder mixture, which contains a soft magnetic powder and an insulating powder lubricant in an amount of 0.1% by mass or more relative to the soft magnetic powder, is formed by compacting at a compacting pressure of 800 MPa or less, thereby obtaining a powder compact that has a space factor of the soft magnetic powder of 93% or more. The powder compact can be used as a soft magnetic powdered core. The soft magnetic powdered core has a specific resistance or 10,000 &#x3bc;&#x3a9;cm or more. A powder of a metal soap such as barium stearate or lithium stearate is used as the insulating powder lubricant.

Soft magnetic powdered core and method for producing same

A method for producing a soft magnetic powdered core includes preparing a mixture of a soft magnetic powder and a resin powder, compacting the mixture into a predetermined shape so as to obtain a compact, and heating the compact. The resin powder has a median size of not more than 30 &#x3bc;m, a maximum particle size of not more than 100 &#x3bc;m, and a specific surface area of not less than 1.0 m/cm, and the additive amount thereof is 0.005 to 2 vol %.

Method for producing soft magnetic powdered core

A method for producing a soft magnetic powdered core comprises a mixing step for forming a raw powder by adding a thermoplastic resin powder to a soft magnetic powder and mixing them, a compacting step for forming a compact by compacting the raw powder into a predetermined shape, a melting and setting step for the resin in which the resin of the compact is melted by heating to at least the melting point of the thermoplastic resin and the melted resin is set by cooling to a room temperature, and a crystallizing step for the resin in which the set resin is heated to not less than the exothermic onset temperature and not more than the endothermic onset temperature, which are measured by DSC analysis of the thermoplastic resin, and is cooled to a room temperature.

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Matsudo, Japan

Kohei Muramatsu