Tdk Corporation

Miyuki Asai

Hitoshi Ohkubo

Masazumi Arata

Kyohei Tonoyama

Kentaro Saito

Hokuto Eda

Ken Satoh

Satoshi Sugimoto

Takahiro Kawahara

Takamasa Iwasaki

To provide a coil device capable of preventing a short circuit between turns of the coil part. A coil deviceincludes a core partincluding a magnetic powderand a resin, and a coil partembedded in the core partand having a wound wirewith an insulation coating layer

Coil device

In a coil component, the pressure resistance is improved by main surfaces and of a main body portion being covered with an insulating layer. The main body portion has a surface part, the resin ratio of the surface part is higher than the internal resin ratio, and insulation is enhanced at the surface part. As a result, the pressure resistance on the surface of the main body portion is further improved and the pressure resistance of the entire coil component is further improved.

Coil component

In a coil component, a second magnetic portion disposed in the vicinity of a coil is designed to have a higher proportion of Fe than a metal magnetic powder-containing resin constituting a first magnetic portion. Therefore, a magnetic flux of the coil flows smoothly. Although the second magnetic portion has a relatively lower withstand voltage than the first magnetic portion, since the second magnetic portion is surrounded by the first magnetic portion, it is not exposed on an outer surface of a magnetic body. For this reason, a situation in which the coil and external terminal electrodes are short-circuited with the second magnetic portion therebetween is effectively curbed, and short-circuiting between the coil and the external terminal electrodes can be curbed.

In a coil component, an uneven structure provided by an insulation layer and a resin wall contributes to extension of a contact area with respect to a magnetic body, so that an adhesive force with respect to the magnetic body is improved. In addition, the magnetic body protrudes downward toward an exposed region of the resin wall corresponding to a recessed portion in the uneven structure, a volume thereof is increased, and coil characteristics such as an inductance value are improved.

A magnetic core includes a metal magnetic powder, which has a large size powder, an intermediate size powder, and a small size powder. A particle size of the large size powder is 10 &#x3bc;m or more and 60 &#x3bc;m or less. A particle size of the intermediate size powder is 2.0 &#x3bc;m or more and less than 10 &#x3bc;m. A particle size of the small size powder is 0.1 &#x3bc;m or more and less than 2.0 &#x3bc;m. The large size powder, the intermediate size powder, and the small size powder have an insulation coating. When A1 represents an average insulation coating thickness of the large size powder, A2 represents an average insulation coating thickness of the intermediate size powder, A3 represents an average insulation coating thickness of the small size powder, A3 is 30 nm or more and 100 nm or less, A3/A1&#x2265;1.3, and A3/A2&#x2265;1.0.

Magnetic core and coil component

A magnetic core and a coil component with excellent permeability, core loss, DC superimposition property, and withstand voltage. A magnetic core has a metal magnetic powder containing resin including a metal magnetic powder. The metal magnetic powder includes a large size powder, an intermediate size powder, and a small size powder. A particle size of the large size powder is 10 &#x3bc;m or more and 60 &#x3bc;m or less. A particle size of the intermediate size powder is 2.0 &#x3bc;m or more and less than 10 &#x3bc;m. A particle size of the small size powder is 0.1 &#x3bc;m or more and less than 2.0 &#x3bc;m. The large size powder includes a nano crystal. A ratio of the large size powder existing with respect to the metal magnetic powder is 39% or more and 91% or less in terms of an area ratio in a cross section of the magnetic core.

In a coil component, an insulation layer covers an upper surface of a conductor pattern. Accordingly, insulating properties between the conductor pattern and a magnetic body are enhanced, and insulating properties between the conductor patterns are enhanced. In addition, in the coil component, the magnetic body enters a space between resin walls such that the insulation layer is covered. Therefore, a volume of the magnetic body above the conductor pattern is increased, and high coil characteristics are realized.

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Tokyo, Japan

Miyuki Asai