Ferrite Laminate Noise Suppression Sheet Wide Frequency Range
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Solution Overview
Problem
Conventional noise suppression sheets are ineffective at frequencies below several tens of MHz, failing to provide sufficient noise suppression for electronic devices that generate noise across a wide range of frequencies from 10 MHz to 1 GHz.
Innovation Solution
A ferrite laminate comprising a conductive layer with a conductive filler and resin, and a magnetic layer made of sintered ferrite with a specific composition (47-50 mol% Fe2O3, 8-16 mol% NiO, 24-35 mol% ZnO, and 7-12.5 mol% CuO), laminated with an adhesive or protective layer, which achieves transmission attenuation of 3.6-8 dB at 1 GHz and 12-30 dB at 10 MHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise suppression sheets are used, then noise suppression at high frequencies (several hundreds of MHz to several GHz) is achieved, but noise suppression at low frequencies (10 MHz to several tens of MHz) is insufficient
Solution Approach 1:
The invention uses a composite structure consisting of a conductive layer (with conductive filler and resin) and a magnetic layer (with sintered ferrite and resin). This composite material approach enables the noise suppression sheet to effectively suppress noise across a wide frequency range from 10 MHz to 1 GHz, overcoming the limitation of conventional sheets that only work well at high frequencies.
Solution Approach 2:
The invention optimizes specific parameters including the complex magnetic permeability (real part μ' and imaginary part μ'') and volume resistivity of the sintered ferrite. By controlling these parameters within specific ranges, the noise suppression sheet achieves effective noise suppression at both low frequencies (10 MHz) and high frequencies (1 GHz), expanding the frequency range coverage.
2Object-affected harmful factors
If Ni-Zn ferrite sintered ceramics are used to reduce electromagnetic wave reflection, then reflection reduction at 10 MHz to 1 GHz is achieved, but the amount of electromagnetic waves absorbed is as small as several percent
Solution Approach 1:
The invention combines a conductive layer with a magnetic layer containing sintered ferrite in a resin matrix. This composite structure enhances both the reflection reduction and absorption capabilities, achieving significantly higher electromagnetic wave absorption (12-30 dB at 10 MHz and 3.6-8 dB at 1 GHz) compared to conventional Ni-Zn ferrite sheets.
Solution Approach 2:
The invention optimizes the complex magnetic permeability parameters (real part μ' = 130-480 and imaginary part μ'' = 30-440 at 10 MHz) and volume resistivity of the sintered ferrite. These parameter optimizations enable the material to achieve both low reflection and high absorption of electromagnetic waves across the frequency range.
3Volume of moving object
If high-density packaging of electronic parts is implemented, then device size and weight are reduced, but unnecessary radiation from electronic devices increases
Solution Approach 1:
The invention converts the harmful unnecessary radiation generated by high-density packaged electronic devices into a manageable issue by providing a noise suppression sheet that absorbs and dissipates this radiation. The sheet transforms the harmful electromagnetic noise into heat energy through controlled absorption, allowing continued use of high-density packaging while eliminating the adverse radiation effects.
Solution Approach 2:
The invention optimizes the volume resistivity and complex magnetic permeability of the sintered ferrite to achieve effective noise suppression. By controlling these parameters, the noise suppression sheet can handle the increased radiation from high-density packaged devices, converting the harmful radiation into acceptable heat dissipation.
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 ferrite laminate effectively absorbs noise across both high-frequency (1 GHz) and low-frequency (10 MHz) bands, making it suitable for use in mobile electronic devices as a noise suppression sheet.
Implementation Method 1
a magnetic layer comprising a sintered ferrite... an amount of transmission attenuation of the ferrite laminate is 12 to 30 dB as measured at 10 MHz... the noise suppression sheet is capable of exhibiting a sufficient noise suppressing effect even at a frequency of 10 MHz
Implementation Method 2
a conductive layer comprising a conductive filler and a resin... a real part of a magnetic permeability of the magnetic layer as measured at 10 MHz is 130 to 480, and an imaginary part of the magnetic permeability of the magnetic layer as measured at 10 MHz is 30 to 440
Data Source
AI summary
In accordance with the present invention, there is provided a noise suppression sheet that is capable of absorbing noise at a wide frequency range of from 10 MHz to 1 GHz. The present invention relates to a ferrite laminate formed by laminating a conductive layer comprising a conductive filler and a resin and a magnetic layer comprising ferrite; the conductive layer has a surface electrical resistance of of 100 to 5000 Ω/□; the ferrite is partitioned into small parts; and a real part of a magnetic permeability of the ferrite as measured at 10 MHz is 130 to 480, and an imaginary part of of the magnetic permeability of the ferrite as measured at 10 MHz is 30 to 440.