Coil Magnetic Base Body With Si-Rich Particle Surfaces
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Solution Overview
Problem
The challenge lies in achieving a high Fe content ratio in soft magnetic metal particles for magnetic base bodies while maintaining excellent insulation performance, as high Fe content ratios during heat treatment lead to excessive oxidation, and low oxygen concentrations result in insufficient oxide film formation, compromising magnetic properties.
Innovation Solution
The solution involves creating a magnetic base body with soft magnetic metal particles containing Fe, Si, and an element like Cr or Al, where the Si content is higher in the surface region than the central region, forming Si—O precipitates that inhibit oxygen penetration and ensure a sufficient oxide film for insulation, even at high Fe content ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Fe content ratio in soft magnetic metal particles is increased to improve magnetic permeability and DC bias characteristics, then magnetic properties are improved, but excessive oxidation occurs during heat treatment compromising insulation performance
Solution Approach 1:
The patent applies local quality by creating a non-uniform Si distribution within the soft magnetic metal particles, with higher Si concentration at the surface region and lower Si concentration in the central region. This gradient distribution allows the surface to form a sufficient oxide film for insulation while the central region maintains high Fe content for magnetic properties, thus resolving the contradiction between magnetic performance and insulation performance.
2Object-generated harmful factors
If heating is performed in an atmosphere with low oxygen concentration to control Fe oxidation, then oxidation is controlled, but the oxide film thickness becomes insufficient compromising electrical insulation
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition distribution within the particles, specifically creating a Si concentration gradient. This compositional parameter change enables the surface region to provide sufficient oxygen for oxide film formation even when the overall oxygen concentration in the heating atmosphere is controlled to prevent excessive Fe oxidation, thus maintaining both oxidation control and electrical insulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for a high Fe content ratio in the magnetic base body while maintaining excellent insulation performance, enhancing magnetic permeability and DC bias characteristics by controlling oxide film thickness and distribution.
Implementation Method 1
During the heat treatment, the additive elements (e.g., Si, Cr, Al) contained in the powder particles are oxidized on the surface of each powder particle. Thus, an oxide film containing oxides of the elements of the raw material powder is formed on the surface of the soft magnetic metal particles.
Implementation Method 2
Each of the plurality of first soft magnetic metal particles includes a plurality of Si—O precipitates containing Si and O in the surface region
Implementation Method 3
The surfaces of the soft magnetic metal particles are covered with insulating films, and adjacent soft magnetic metal particles are bonded to each other via the insulating films.
Data Source
AI summary
A coil component includes: a magnetic base body including a plurality of soft magnetic metal particles that contain Fe and Si, and an oxide film provided on the surface of each of the plurality of soft magnetic metal particles; and a coil conductor provided in the magnetic base body. The oxide film contains an oxide of Si and an oxide of element A (wherein the element A is at least one selected from the group consisting of Cr and Al). Each soft magnetic metal particle is divided into a central region and a surface region radially outward of the central region. The surface region contains a higher atomic proportion of Si than the central region. The soft magnetic metal particles include first soft magnetic metal particles that include Si—O precipitates separated from each other in the surface region.