# US 2025/0157724 A1 · Multilayer coil component

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- Number: US 2025/0157724 A1
- Document ID: US20250157724A1
- Status: Published application
- Kind: A1
- Application number: 19/022,371
- Filed: 2025-01-15
- Published: 2025-05-15
- Earliest claimed: 2020-10-02
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Yusuke NAGAI; Takashi SUZUKI; Kazuhiro EBINA; Kunihiko KAWASAKI; Shinichi KONDO; Keito YASUDA; Ryuichi WADA; Makoto MORITA; Takashi KUDO; Kyohei TONOYAMA
- Web page: https://patentgrep.com/patent/US20250157724A1

## CPC

- H01F 27/292: {Surface mounted devices}
- H01F 17/0013: {with stacked layers}
- H01F 17/04: with magnetic core
- H01F 2017/048: {with encapsulating core, e.g. made of resin and magnetic powder}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

In a multilayer coil component, a part filled with a resin and a void part not filled with the resin exist between a plurality of metal magnetic particles in an element body, one main surface of the element body is a mounting surface with respect to an external electronic component, and the edge of an external electrode is positioned on the mounting surface. In the element body, a high void region where the porosity caused by the void part is higher than the porosity of the other part in the element body extends from the edge of the external electrode on the mounting surface toward an end surface of the element body.

## Claims

### Claim 1

A multilayer coil component comprising:
an element body containing a plurality of metal magnetic particles;
a coil disposed in the element body; and
an external electrode disposed so as to cover an end surface of the element body and electrically connected to the coil, wherein
a part filled with a resin and a void part not filled with the resin exist between the plurality of metal magnetic particles in the element body,
one surface of the element body other than the end surface is a mounting surface with respect to an external electronic component and an edge of the external electrode is positioned on the mounting surface,
a high void region where porosity caused by the void part is higher than porosity of another part in the element body extends from the edge of the external electrode on the mounting surface toward the end surface of the element body in the element body, and
the high void region has a formation depth extending from the mounting surface along a direction orthogonal to the mounting surface, and the formation depth of the high void region decreases from the edge of the external electrode toward the end surface of the element body.

### Claim 2

A multilayer coil component comprising:
an element body containing a plurality of metal magnetic particles;
a coil disposed in the element body; and
an external electrode disposed so as to cover an end surface of the element body and electrically connected to the coil, wherein
a part filled with a resin and a void part not filled with the resin exist between the plurality of metal magnetic particles in the element body,
one surface of the element body other than the end surface is a mounting surface with respect to an external electronic component and an edge of the external electrode is positioned on the mounting surface,
a high void region where porosity caused by the void part is higher than porosity of another part in the element body extends from the edge of the external electrode on the mounting surface toward the end surface of the element body in the element body,
the high void region includes:
a first formation depth extending from a portion of the mounting surface on which the edge of the external electrode is positioned along a direction orthogonal to the mounting surface, and
a second formation depth extending from a portion of the mounting surface on which the external electrode is not positioned along the direction orthogonal to the mounting surface, and
the first formation depth is greater than the second formation depth.

### Claim 3 (depends on 1)

The multilayer coil component according to claim 1, wherein the external electrode is a baking electrode.

### Claim 4 (depends on 1)

The multilayer coil component according to claim 1, wherein the high void region extends to the end surface of the element body.

### Claim 5 (depends on 1)

The multilayer coil component according to claim 1, wherein the high void region is separated from the coil.

### Claim 6 (depends on 2)

The multilayer coil component according to claim 2, wherein the external electrode is a baking electrode.

### Claim 7 (depends on 2)

The multilayer coil component according to claim 2, wherein the high void region extends to the end surface of the element body.

### Claim 8 (depends on 2)

The multilayer coil component according to claim 2, wherein the high void region is separated from the coil.