CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent Application No. 2020-025658, filed Feb. 18, 2020, the disclosure of which is incorporated herein by reference in its entirety including any and all particular combinations of the features disclosed therein.

BACKGROUND

Field of the Invention

The present invention relates to a magnetic base body, a coil component, and an electronic device.

Description of the Related Art

Coil components that use metal magnetic grains offering excellent direct-current superimposition property, instead of ferrite, have been proposed. Since metal magnetic grains are low in insulating property, an art of coating the surface of metal magnetic grains with silicon oxide films, aluminum oxide films, or other insulating films is known. For example, magnetic base bodies, each comprising metal magnetic grains coated with an insulating film, and a glass component containing silicon, boron, and alkali metal, are known (refer to Patent Literature 1, for example). Also, magnetic base bodies, each comprising metal magnetic grains coated with an insulating film, and a silicone resin, are known (refer to Patent Literature 2, for example).

BACKGROUND ART LITERATURES

[Patent Literature 1] International Patent Laid-open No. 2014/024976[Patent Literature 2] Japanese Patent Laid-open No. 2019-153614

SUMMARY

It is desired that, to improve the reliability of coil components, their magnetic base bodies have high insulation reliability and mechanical strength. Also, conceivably, magnetic base bodies can be formed by bonding together the oxide films on multiple metal magnetic grains whose surface has been covered with an oxide film, in order to increase the filling rate of metal magnetic grains and thereby achieve better magnetic properties, for example. In this case, heat treatment at high temperature is needed to bond together the oxide films on metal magnetic grains. For example, heat treatment is performed at high temperature in Patent Literature 2. When subjected to heat treatment at high temperature, however, the metal magnetic grains will bond directly over the oxides (necking). This makes it difficult to administer heat treatment at high temperature in a manner preventing the metal magnetic grains from sintering, which consequently makes it difficult to obtain a magnetic base body having high mechanical strength.

The present invention was made in light of the aforementioned problems, and its object is to improve the mechanical strength while ensuring insulation reliability.

The present invention is a magnetic base body comprising multiple metal magnetic grains and bonding parts for bonding the multiple metal magnetic grains, wherein the bonding parts are constituted by an amorphous mixture containing carbon and an oxide of at least one element selected from silicon, aluminum, chromium, magnesium, titanium, and zirconium.

The aforementioned constitution may be a constitution where, when the total quantity by mol of silicon, aluminum, chromium, magnesium, titanium, and zirconium contained in the bonding parts is 1, the ratio by mol of carbon in the bonding parts is 5 or lower.

The aforementioned constitution may be a constitution where, when the total quantity by mol of silicon, aluminum, chromium, magnesium, titanium, and zirconium contained in the bonding parts is 1, the ratio by mol of carbon in the bonding parts is 0.4 or higher.

The aforementioned constitution may be a constitution where there are oxide films covering the surface of the multiple metal magnetic grains at least partially and containing substantially no carbon in the film, and the bonding parts bond the multiple metal magnetic grains as a result of their oxide films bonding together via the bonding parts.

The aforementioned constitution may be a constitution where the amorphous mixture constituting the bonding parts contains an oxide of silicon as its primary component.

The aforementioned constitution may be a constitution where the primary component of the multiple metal magnetic grains is iron.

The present invention is a coil component comprising the aforementioned magnetic base body and a coil conductor provided in the magnetic base body.

The present invention is an electronic device comprising the aforementioned coil component and a circuit board on which the coil component is mounted.

According to the present invention, mechanical strength can be improved while ensuring insulation reliability.

