Antenna Shielding Sheet Structure for Thin High-Permeability Design
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Solution Overview
Problem
Conventional magnetic field shielding sheets face challenges in achieving high magnetic permeability of 2,000 or more while maintaining a thin thickness, as they require a flake process that increases production costs and decreases magnetic permeability due to repeated separation into smaller pieces, leading to increased resistance and eddy current issues.
Innovation Solution
A magnetic field shielding sheet is designed with through-portions and cracks formed locally in partial regions, using a manufacturing method that avoids the need for a separate flake process, allowing for high magnetic permeability and thin thickness by selectively forming these features in areas corresponding to an antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flake process is performed repeatedly to separate the sheet into smaller pieces, then the flexibility and eddy current reduction are improved, but the magnetic permeability decreases to 1,500 or less and production costs increase
Solution Approach 1:
The sheet is segmented into a land portion and a pattern portion with different structures. The pattern portion contains through-portions and cracks that provide flexibility and reduce eddy currents, while the land portion maintains high magnetic permeability. This selective segmentation resolves the contradiction by applying different structural characteristics to different functional regions.
Solution Approach 2:
Different regions of the sheet are given different qualities: the pattern portion has through-portions and cracks for flexibility and eddy current reduction, while the land portion remains intact for high magnetic permeability. This local differentiation allows simultaneous achievement of both flexibility and high magnetic permeability in different areas.
2Reliability
If the overall thickness of the sheet is increased to achieve high magnetic permeability of 2,000 or more, then the magnetic permeability requirement is met, but the thin thickness design goal is compromised
Solution Approach 1:
The sheet maintains thin overall thickness while achieving high magnetic permeability through local quality differentiation. The land portion provides high magnetic permeability in a thin configuration, while the pattern portion's through-portions and cracks provide the necessary flexibility without requiring increased thickness.
3Loss of energy
If a separate flake process is performed to form the shielding sheet, then the eddy current loss is reduced, but the production cost increases
Solution Approach 1:
The formation of through-portions and cracks is merged with the existing sheet manufacturing process rather than being a separate flake process. This integration reduces production costs while still achieving eddy current reduction through the patterned through-portions and cracks in the pattern portion.
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 magnetic field shielding sheet with a magnetic permeability of 2,000 or more and a thickness of 55 μm to 85 μm, reducing eddy current influence and enhancing antenna inductance while maintaining flexibility and reducing production costs.
Implementation Method 1
a sheet body formed as a ribbon sheet including at least one selected from an amorphous alloy and a nanocrystalline alloy
Implementation Method 2
a plurality of through-portions formed in a region of the sheet body corresponding to the pattern portion, and a plurality of cracks formed to extend from the through-portions
Data Source
AI summary
Provided is a magnetic field shielding sheet. A magnetic field shielding sheet according to an exemplary embodiment of the present invention is a magnetic field shielding sheet for an antenna, which includes a hollow portion having a predetermined area in a central portion thereof and a pattern portion configured to surround the hollow portion, includes a sheet body formed as a ribbon sheet including at least one selected from an amorphous alloy and a nanocrystalline alloy, a plurality of through-portions formed in a region of the sheet body corresponding to the pattern portion, and a plurality of cracks formed to extend from the through-portions.