Common Mode Filter with Magnetic Particle-Resin Composite
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Solution Overview
Problem
Conventional common mode filters are too large and have poor electrical properties, limiting their application in miniaturized electronic devices, and struggle to effectively manage signal delays and noise at high frequency bands, especially in devices like digital TVs with complex internal circuits.
Innovation Solution
A common mode filter with a magnetic substrate, a multilayer coil pattern structure, and a magnetic particle-resin composite layer containing fine and coarse magnetic particles, where the core part has an average particle diameter of 30 μm or less and the cover part includes both fine and coarse particles, filling a cavity of 50 μm diameter without voids, ensuring high permeability and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wound-type or multilayer-type common mode filters are used, then electromagnetic wave interference protection is provided, but the device size becomes large and electrical properties deteriorate
Solution Approach 1:
The patent employs a thin film-type common mode filter structure where coil patterns are formed on a substrate and covered with a thin magnetic particle-resin composite layer. This thin film approach enables the filter to be miniaturized while maintaining electromagnetic interference protection functionality, directly resolving the contradiction between providing EMI protection and reducing device size.
Solution Approach 2:
The patent uses a magnetic particle-resin composite layer combining fine magnetic particles (average particle diameter of 30 μm or less) with a resin binder. This composite material structure provides both the magnetic properties needed for EMI protection and the mechanical flexibility required for thin film fabrication, enabling small-size implementation while maintaining reliability.
2Volume of moving object
If conventional common mode filters are miniaturized for thinned electronic products, then device thickness is reduced, but manufacturing complex internal circuits in small area becomes limited
Solution Approach 1:
The patent replaces complex three-dimensional internal circuit structures with a planar thin film structure where coil patterns are formed on a substrate surface. This substitution of mechanical/structural complexity with planar patterning enables miniaturization while maintaining ease of manufacture through standard thin film fabrication processes.
Solution Approach 2:
The patent changes the structural parameters from thick multilayer or wound configurations to thin film dimensions, with the magnetic particle-resin composite layer having a thickness suitable for thin film processing. This parameter change enables both device thinning and compatibility with standard manufacturing processes for forming complex patterns in small areas.
3Speed
If high frequency signals are transmitted to increase data capacity, then transmission rate increases, but common mode noise and signal delays occur
Solution Approach 1:
The patent uses the magnetic particle-resin composite layer to convert the harmful high-frequency electromagnetic noise into beneficial magnetic flux that is guided through the magnetic particles. The fine magnetic particles with specific permeability characteristics absorb and redirect common mode noise, transforming it from a harmful interference into a controlled magnetic field that enhances filter performance while allowing high-speed signal transmission.
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 solution enables a compact common mode filter with sufficient impedance, reducing signal delays and noise, suitable for miniaturized electronic devices by maintaining high inductance and permeability while preventing void formation in the cavity.
Implementation Method 1
the core part may contain fine magnetic particles having an average particle diameter of 30 μm or less, and the cover part may contain fine magnetic particles having an average particle diameter of 30 μm or less and coarse magnetic particles having an average particle diameter greater than that of the fine magnetic particles
Data Source
AI summary
A common mode filter includes a substrate; an insulating layer disposed on the substrate and including coil patterns, the insulating layer having a cavity disposed in a central portion therein; and a magnetic particle-resin composite layer including a core part filling the cavity and a cover part covering the insulating layer. The core part contains fine magnetic particles having an average particle diameter of 30 μm or less, and the cover part contains the fine magnetic particles having the average particle diameter of 30 μm or less and coarse magnetic particles having an average particle diameter greater than that of the fine magnetic particles.