Insulating Magnetic Metal Particles with Eutectic Oxide Layers
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Solution Overview
Problem
Existing methods for manufacturing insulating magnetic materials with high relative magnetic permeability face challenges such as high transmission loss due to eddy currents, agglomeration of magnetic metal particles, and difficulty in achieving uniform film quality and cost-effectiveness, particularly at high frequencies.
Innovation Solution
The development of insulating magnetic metal particles with a magnetic metal core coated by a first and second inorganic oxide layer, where the second layer forms a eutectic crystal upon heating, maintaining the first layer on the surface, and the particles are molded and heated to produce a eutectic crystal, enhancing magnetic properties and reducing eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal or alloy is used in high relative magnetic permeability material, then magnetic properties are improved, but transmission loss due to eddy currents becomes remarkable at high frequencies
Solution Approach 1:
The magnetic material is segmented into fine particles with a maximum diameter of 10 μm, which divides the continuous metal structure into discrete units. This segmentation interrupts eddy current paths, reducing transmission loss while maintaining magnetic properties through the collective behavior of the particles.
Solution Approach 2:
The invention uses composite material structure consisting of magnetic metal particles combined with insulating material. The insulating material surrounds the magnetic particles, providing electrical isolation that suppresses eddy currents while the magnetic particles maintain the high relative magnetic permeability needed for effective operation.
2Loss of energy
If insulating oxide such as ferrite is used to suppress eddy currents, then transmission loss is reduced, but the material approaches resonant frequency at high frequencies causing remarkable transmission loss
Solution Approach 1:
The invention creates a composite material that combines magnetic metal particles with insulating material, achieving a balance between eddy current suppression and frequency response. The magnetic metal particles provide high relative magnetic permeability while the insulating matrix prevents eddy currents, and the composite structure avoids the resonant frequency issues of pure ferrite materials.
3Loss of energy
If magnetic metal particles are dispersed in insulating material, then eddy currents are suppressed, but particles tend to agglomerate reducing dispersibility
Solution Approach 1:
An insulating coating layer is formed on the surface of each magnetic metal particle. This thin film shell prevents direct contact between magnetic particles, reducing magnetic attraction and preventing agglomeration. The coating maintains particle dispersibility in the insulating material while preserving the eddy current suppression benefits.
4Reliability
If thin film technique such as sputtering is used to manufacture nanogranular material, then high relative magnetic permeability is achieved, but large-scaled facilities are required and film formation rate is very slow
Solution Approach 1:
The invention replaces the mechanical thin film deposition process (sputtering) with a particle-based approach. Magnetic metal particles are dispersed in an insulating material matrix to form a molded body, which is then sintered. This substitution eliminates the need for large-scaled thin film facilities and achieves much higher formation rates while maintaining high relative magnetic permeability.
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 results in insulating magnetic materials with high relative magnetic permeability, improved thermal stability, and effective high-frequency characteristics, suitable for applications like antenna substrates, while maintaining the shape and magnetic properties of the magnetic metal particles.
Implementation Method 1
a second inorganic insulating layer made of an oxide which produces a eutectic crystal by reacting together with the first inorganic insulating layer at the time of heating them
Implementation Method 2
heating the molded body to produce the eutectic crystal by reacting between the first and second insulating layers
Data Source
AI summary
An insulating magnetic metal particle includes a magnetic metal particle containing at least one metal selected from the group consisting of Co, Fe, and Ni and having a diameter of 5 to 500 nm, a first inorganic insulating layer made of an oxide that covers the surface of the magnetic metal particle, and a second inorganic insulating layer made of an oxide that produces a eutectic crystal by reacting together with the first inorganic insulating layer at the time of heating them, the second inorganic insulating layer being coated on the first inorganic insulating layer. A thickness ratio of the second inorganic insulating layer with respect to the first inorganic insulating layer is set so that the first inorganic insulating layer remains on the surface of the magnetic metal particle after producing the eutectic crystal.