Composite Magnetic Core Structure for Wideband EMI Filtering
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Solution Overview
Problem
Inductors with Mn—Zn-based ferrite magnetic cores face challenges in maintaining strength and magnetic properties after high-temperature heat treatment, leading to brittleness and poor workability, which affects the performance and yield of EMI filters.
Innovation Solution
A magnetic core configuration featuring a first ferrite-based body with a second Fe—Si-based metal ribbon wound in multiple layers, coated with a resin material to enhance strength and magnetic properties, including a specific resin distribution in interlayer spaces to improve noise removal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature heat treatment is applied to metal ribbon to improve magnetic properties, then magnetic permeability is improved, but strength is excessively reduced and brittleness increases
Solution Approach 1:
The patent uses a composite structure consisting of a metal ribbon core with ferrite particles dispersed within a resin matrix. This composite material provides both the magnetic properties needed for EMI filtering and the mechanical strength required for handling, resolving the contradiction between magnetic performance and structural integrity after heat treatment.
Solution Approach 2:
The patent changes the material parameters by dispersing ferrite particles within the resin-coated metal ribbon structure. This parameter modification allows the material to maintain magnetic permeability while gaining enhanced mechanical strength and impact resistance, eliminating the need for high-temperature heat treatment that would otherwise cause brittleness.
2Reliability
If Mn—Zn-based ferrite material is used in magnetic core, then magnetic permeability within 100 kHz to 1 MHz is improved, but common-mode noise removal at high frequencies becomes insufficient
Solution Approach 1:
The patent creates a composite magnetic material by dispersing ferrite particles within a resin matrix that coats the metal ribbon. This composite structure combines the high magnetic permeability of ferrite at lower frequencies with the high-frequency noise filtering capabilities of the metal ribbon, achieving broad-spectrum EMI suppression.
Solution Approach 2:
The patent applies different material properties to different frequency ranges: the ferrite particles provide high magnetic permeability for lower frequency noise (100 kHz to 1 MHz), while the metal ribbon structure handles high-frequency common-mode noise. This local quality differentiation resolves the contradiction between low-frequency permeability and high-frequency noise removal.
3Reliability
If metal ribbon is made brittle through heat treatment, then magnetic properties are improved, but workability and yield during manufacturing deteriorate
Solution Approach 1:
The patent employs a composite structure where ferrite particles are dispersed in a resin matrix that coats the metal ribbon. This composite approach provides the necessary magnetic properties without requiring high-temperature heat treatment that would cause brittleness, thereby maintaining ease of manufacturing and handling throughout the production process.
Solution Approach 2:
The resin matrix acts as a protective cushioning layer that prevents the metal ribbon from becoming brittle. By incorporating the ferrite particles within this protective matrix before manufacturing processes, the material maintains its mechanical strength and workability throughout production while still achieving the desired magnetic properties.
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
The configuration effectively improves the magnetic core's strength and noise removal capabilities over a wide frequency band, preventing magnetic flux concentration and enabling application in high-power products with adjustable performance through permeability adjustments.
Implementation Method 1
preventing magnetic flux concentration
Implementation Method 2
An inductor is one of electronic components that are used in printed circuit boards, and may be applied to resonance circuits, filter circuits, power circuits, etc. due to the electromagnetic characteristics thereof
Implementation Method 3
coated with a resin material to enhance strength and magnetic properties
Data Source
AI summary
An inductor according to an embodiment of the present invention comprises: a first magnetic body having a toroidal shape, and including a ferrite; and a second magnetic body disposed on an outer circumferential surface or an inner circumferential surface of the first magnetic body, wherein the second magnetic body includes: resin material and a plurality of layers of metal ribbons wound along the circumferential direction of the first magnetic body, wherein the resin material comprises a first resin material disposed to cover an outer surface of the plurality of layers of metal ribbons, and a second resin material disposed in at least a part of a plurality of layers of interlayer spaces.