Electromagnetic Noise Suppression Sheet Using Composite Ferrite and Carbon
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Solution Overview
Problem
The challenge is to develop an electromagnetic noise suppression sheet with a smaller thickness that maintains excellent electromagnetic absorption performance and reduced reflection across a wide frequency range, suitable for high-density mounting of electronic parts and wiring circuit boards, while ensuring practical flexibility and strength.
Innovation Solution
The electromagnetic noise suppression sheet comprises 3 to 10% by volume of conductive carbon, 40 to 65% by volume of spinel ferrite particles with a cumulative 50% volume particle diameter of 1 to 10 µm, and a resin selected from styrene-based elastomers, applied in a thickness not exceeding 100 µm, with a production process involving coating and thermoforming under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of electromagnetic noise suppression sheet is reduced, then it becomes suitable for high-density mounting, but electromagnetic absorption performance deteriorates
Solution Approach 1:
The patent uses a composite material consisting of soft magnetic particles (ferrite or amorphous magnetic alloy) dispersed in a resin matrix. This composite structure enables the thin sheet to achieve effective electromagnetic absorption through the magnetic properties of the particles while maintaining flexibility and processability through the resin binder.
Solution Approach 2:
The patent optimizes the particle size parameters of the soft magnetic particles (average diameter 1-10 μm, aspect ratio 1.05-2.0) and their volume concentration (30-70 vol%) to achieve effective electromagnetic absorption in a thin sheet configuration. By carefully controlling these parameters, the sheet achieves good absorption performance at reduced thickness.
2Ease of operation
If the thickness of electromagnetic noise suppression sheet is reduced, then flexibility is improved, but strength deteriorates
Solution Approach 1:
The resin matrix provides mechanical strength and structural integrity to the thin sheet, while the dispersed soft magnetic particles provide electromagnetic absorption functionality. This composite structure allows the sheet to maintain both flexibility and adequate strength at reduced thickness.
Solution Approach 2:
The patent creates a heterogeneous structure where the resin provides continuous matrix support for mechanical strength, while the soft magnetic particles are locally distributed to provide electromagnetic absorption. This local differentiation of material functions allows the thin sheet to achieve both flexibility and sufficient strength.
3Reliability
If soft magnetic particles are blended in resin for electromagnetic absorption, then near electromagnetic field suppression is achieved, but design becomes experience-dependent
Solution Approach 1:
The patent establishes specific parameter ranges for particle size (average diameter 1-10 μm, aspect ratio 1.05-2.0), particle concentration (30-70 vol%), and sheet thickness (10-100 μm) that can be objectively optimized using electromagnetic field theory. This transforms the design from experience-dependent to parameter-driven, enabling systematic optimization of electromagnetic absorption performance.
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 configuration achieves a high transmission attenuation power ratio and low return loss over a wide frequency range, making it suitable for high-density electronic mounting with improved flexibility and strength, suitable for use in flat cables and flexible printed circuit boards.
Implementation Method 1
electromagnetic noise suppression sheets have been used for absorbing electromagnetic radiation in the near electromagnetic magnetic field
Implementation Method 2
electromagnetic noise suppression sheets of such a type in which flat magnetic metal particles as soft magnetic particles are blended in a resin, have been used for absorbing electromagnetic radiation
Implementation Method 3
after a magnetic coating material obtained by dispersing flat magnetic metal particles in a resin and a solvent is applied onto a substrate having a release layer and then dried
Implementation Method 4
subjecting the thus dried coating film to thermoforming under pressure
Data Source
AI summary
An electromagnetic noise suppression sheet obtained by using combination of a conductive carbon and spinel ferrite particles having a cumulative 50% volume particle diameter of 1 to 10 µm, can exhibit an excellent transmission attenuation power ratio and a reduced return loss in a near electromagnetic field, and is suitable for high-density mounting. The electromagnetic noise suppression sheet of the present invention can be produced by the process of the present invention which includes the steps of applying a coating material in which the conductive carbon and the spinel ferrite particles having a cumulative 50% volume particle diameter of 1 to 10 µm are dispersed, to form a coating film having a thickness of 10 to 100 µm after dried, and subjecting the resulting coating film to thermoforming under pressure.