US-12624431-B2 - Coil component and method for manufacturing same

US12624431B2US 12624431 B2US12624431 B2US 12624431B2US-12624431-B2

Abstract

A magnetic body of the coil component contains, as soft magnetic alloy grains, first grains whose alloy components are substantially Fe, Si, and Cr, and second grains which contain, as alloy components, Fe, Si, and an element other than Si or Cr that oxidizes more easily than Fe; the first grains have, on their surface, an amorphous oxide film containing Si and Cr; the second grains have, on their surface, a crystalline oxide layer containing the element other than Si or Cr that oxidizes more easily than Fe; and the crystalline oxide forms adhesion parts, each contacting a multiple number of the first grains via the amorphous oxide film thereof and coupling or bridging the multiple number of the first grains. The coil component can offer improved mechanical strength.

Inventors

Yoko ORIMO
Tomoo Kashiwa

Assignees

TAIYO YUDEN CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20230627
Priority Date: 20190830

Claims (7)

1 . A coil component comprising: a magnetic body containing soft magnetic alloy grains; and a conductor embedded in the magnetic body or placed on the surface of the magnetic body; the coil component characterized in that the magnetic body contains, as soft magnetic alloy grains, first grains whose alloy components are substantially or consists essentially of Fe, Si, and Cr, as well as second grains which contain, as alloy components, Fe, Si, and an element other than Si or Cr that oxidizes more easily than Fe; wherein, the first grains and the second grains are mixed throughout the magnetic body; the first grains and the second grains are different in that the first grains have, on their surface, an amorphous oxide film containing Si and Cr, whereas the second grains have, on their surface, a layer of crystalline oxide containing the element other than Si or Cr that oxidizes more easily than Fe; and the crystalline oxide forms adhesion parts, each contacting a multiple number of the first grains via the amorphous oxide film thereof and coupling or bridging the multiple number of the first grains throughout the magnetic body.
2 . The coil component according to claim 1 , wherein a ratio by mass of Fe in the soft magnetic alloy grains is 30 to 98%.
3 . The coil component according to claim 1 , wherein the crystalline oxide is monocrystalline.
4 . The coil component according to claim 1 , wherein the element other than Si or Cr that oxidizes more easily than Fe is Al or Mn.
5 . The coil component according to claim 1 , wherein the adhesion parts fills voids between the soft magnetic alloy grains.
6 . A circuit board carrying the coil component according to claim 1 .
7 . The coil component according to claim 1 , wherein the layer of crystalline oxide is thicker than the amorphous oxide film.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 16/995,174, filed Aug. 17, 2020, which claims priority to Japanese Patent Application No. 2019-157979, filed Aug. 30, 2019, each disclosure of which is incorporated herein by reference in its entirety. The applicant herein explicitly rescinds and retracts any prior disclaimers or disavowals or any amendment/statement otherwise limiting claim scope made in any parent, child or related prosecution history with regard to any subject matter supported by the present application. BACKGROUND Field of the Invention The present invention relates to a coil component and a method for manufacturing the same. Description of the Related Art For coil components, inductance and other basic properties are determined by which magnetic body and conductor are combined. In particular, the properties of a coil component are significantly affected by the magnetic material that constitutes its magnetic body and therefore, normally, different coil components use different magnetic materials according to their construction, use environment, etc. For example, ferrite-type magnetic materials offering excellent dielectric strength are often adopted by coil components for automobiles that are required to operate at high voltage. In recent years, however, metal magnetic materials are beginning to replace ferrite types for use in coil components for automobiles. This is because metal magnetic materials, which are less likely to saturate magnetically compared to ferrite-type materials, allow for size reduction of coil components. The number of electronic components used on automobiles is increasing in recent years due to their computerization. In the meantime, the space available for installing electronic components and boards carrying electronic components is limited, which is imposing a requirement that the electronic components be made smaller. It is in response to this requirement that coil components featuring metal magnetic materials are beginning to be adopted. Metal magnetic materials, while more advantageous to ferrite types in that they are less likely to saturate magnetically, are inferior to ferrite types in terms of electrical insulating property. For this reason, magnetic bodies made of metal magnetic materials may conduct electricity under high voltage. Magnetic bodies made of metal magnetic materials are constituted by metal magnetic grains that are in contact with one another. Accordingly, various means have been studied for improving the electrical insulating property of these magnetic bodies, with the focus on electrically insulating the surfaces of metal magnetic grains. Additionally, coil components for automobiles are subject to vibration and temperature differences, which means that the magnetic bodies that constitute these coil components must have high mechanical strength and durability, as well. Since the mechanical strength and durability of magnetic bodies made of metal magnetic materials manifest primarily through the joining together of metal magnetic grains, arts of electrically insulating the surfaces of metal magnetic grains while joining the grains together at the same time are also known. For example, Patent Literature 1 discloses an art of heat-treating in air a compact of soft magnetic alloy grains containing iron, silicon, and an element that oxidizes more easily than iron, so that an oxide layer constituted by a metal oxide is produced on the surfaces of the grains, thereby causing the grains to bond together via the oxide layer. Also, Patent Literature 2 discloses an art of coating or depositing TEOS, colloidal silica, or other Si compound around or onto the surfaces of the grains constituting a Fe—Si—Cr soft magnetic alloy powder, after which the powder is compacted and then heat-treated in air, thereby causing the grains to bond together via an oxide phase. BACKGROUND ART LITERATURES [Patent Literature 1] Japanese Patent Laid-open No. 2011-249774[Patent Literature 2] Japanese Patent Laid-open No. 2015-126047 SUMMARY It has been reported that, according to each of the aforementioned means, magnetic bodies and coil components offering excellent mechanical strength can be obtained; however, further improvement in mechanical strength is required of magnetic bodies and coil components. Accordingly, an object of the present invention is to provide a coil component offering improved mechanical strength. After conducting various studies to achieve the aforementioned object, the inventor of the present invention found that a coil component comprises a magnetic body containing soft magnetic alloy grains; and a conductor embedded in the magnetic body or placed on the surface of the magnetic body, wherein the coil component has the characteristics of [1] to [4] below would exhibit high mechanical strength, and eventually completed the present invention. [1] The magnetic body is constituted by soft mag