Fe-B Magnetic Powder Composition for 100 kHz-20 MHz Noise Suppression
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Solution Overview
Problem
Existing noise suppressing sheets, particularly those using ferrite and Fe—Si—Al-based powders, are inefficient in high frequency ranges (100 kHz to 20 MHz) for recent portable electronic devices, leading to radio wave interference issues.
Innovation Solution
A powder for magnetic members composed of an alloy with 5.0 to 8.0 mass % Boron (B) and optional Cr, Mn, Co, or Ni, with an Fe2B phase, providing high permeability and effective noise suppression in the specified frequency range, and potentially coated with an insulation layer for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ferrite is used as magnetic material for noise suppressing sheet, then the sheet can be easily processed and has high flexibility in shape, but the permeability in high frequency region (100 kHz to 20 MHz) is small, resulting in insufficient conversion efficiency from radio wave to magnetism
Solution Approach 1:
The invention changes the magnetic material composition from conventional ferrite to a specific alloy system containing Fe, B (5-15 mass%), and optional elements (Cr, Mn, Co, Ni, Al, Si, Ti, V, Nb, Ta, Mo, W, Cu, Zn, In, Ga, Ge, Pb, Bi, Zr, Hf, Pd, Pt, Ir, Rh, Ag, Au, Ce, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). This compositional parameter change enables high permeability in the 100 kHz to 20 MHz frequency range while maintaining processability.
Solution Approach 2:
The invention uses a composite alloy material combining multiple elements (Fe-B base alloy with optional additive elements) to achieve properties that neither ferrite nor simple Fe-B alloy can provide alone. The composite structure with specific phase composition (Fe2B phase presence) delivers both high frequency performance and manufacturability.
2Reliability
If conventional Fe—Si—Al-based flaky powder is used to achieve high permeability in relatively high frequency region, then the powder is flattened for processing, but the noise suppression in high frequency range close to 20 MHz is insufficient
Solution Approach 1:
The invention modifies the alloy composition parameters by incorporating specific amounts of Boron (5-15 mass%) along with controlled amounts of Cr, Mn, Co, Ni, and other elements. This compositional adjustment shifts the magnetic properties to achieve effective noise suppression up to 20 MHz, overcoming the limitation of Fe-Si-Al based powders.
Solution Approach 2:
The invention optimizes the local chemical composition and phase distribution within the alloy particles, ensuring appropriate content of Fe2B phase and controlled distribution of alloying elements. This local compositional optimization enables the material to exhibit high permeability and effective noise suppression in the critical 100 kHz to 20 MHz range.
3Reliability
If particles are flattened to reduce demagnetizing factor, then high permeability can be achieved, but the particles are not suitable for use in spherical shape and mixture with resin
Solution Approach 1:
The invention changes the particle morphology parameter from flattened shape to spherical shape, and adjusts the alloy composition parameters (Fe-B system with 5-15 mass% B and optional elements) to compensate for the shape change. This enables the spherical particles to achieve high permeability through compositional optimization rather than relying on flattened geometry.
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 powder effectively suppresses noise in the frequency range of 100 kHz to 20 MHz, enhancing electromagnetic wave shielding and absorption properties while maintaining high saturation magnetic flux density.
Implementation Method 1
The noise suppressing sheet converts emitted radiation radio wave (noise) into magnetism, to prevent the emission of radio wave out of an electronic circuit.
Implementation Method 2
The alloy contains an Fe2B phase
Data Source
AI summary
Provided is a powder suitable for a magnetic member capable of suppressing noise in a frequency range of 100 kHz to 20 MHz. The powder for a magnetic member contains a plurality of particles 2. The main part of the particle 2 is made of an alloy. The alloy contains B. The content of B in the alloy is 5.0 mass % or more and 8.0 mass % or less. The alloy may further contain one or more elements selected from the group consisting of Cr, Mn, Co, and Ni. The content of these elements is 0 mass % or more and 25 mass % or less. The balance of the alloy is Fe and unavoidable impurities. The alloy contains an Fe2B phase. The area percentage of the Fe2B phase in the alloy is 20 mass % or more and 80 mass % or less.