NFC Magnetic Sheet Paste with Nanoscale Alumina
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Solution Overview
Problem
Existing NFC magnetic sheets suffer from high magnetic loss due to metal interference in mobile devices, which reduces communication distance and sensitivity, and existing methods struggle to increase the real part of permeability while decreasing the imaginary part effectively.
Innovation Solution
A paste for NFC magnetic sheets comprising magnetic powder, nanoscale alumina powder, and an organic carrier, with specific weight ratios that reduce bridging connections between magnetic powders, thereby increasing the real part of permeability and decreasing the imaginary part, enhancing the quality factor and magnetic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the density of the magnetic sheet is increased to improve magnetic conductivity, then the real part of permeability increases, but the imaginary part of permeability also increases, resulting in increased magnetic loss and reduced quality factor
Solution Approach 1:
The patent introduces a non-magnetic substance as an intermediary between magnetic powder particles. This intermediary material isolates the magnetic particles, preventing direct contact and reducing eddy current formation while maintaining magnetic conductivity through the magnetic powder's intrinsic properties. The non-magnetic substance acts as a buffer that decouples the relationship between density and magnetic loss.
Solution Approach 2:
The patent creates a porous or discontinuous structure by incorporating non-magnetic substances between magnetic particles. This porous arrangement reduces the continuous magnetic pathways that lead to eddy current losses while preserving enough magnetic connectivity for acceptable conductivity. The controlled porosity allows magnetic flux to pass through magnetic particles without creating continuous conductive paths.
2Reliability
If magnetic powder is densely packed to increase the real part of permeability, then magnetic conductivity improves, but eddy current losses increase due to enhanced magnetic coupling between particles
Solution Approach 1:
The patent segments the magnetic material into discrete particles separated by non-magnetic substances. This segmentation breaks the continuous magnetic pathways that cause eddy current losses while maintaining sufficient magnetic coupling through the segmented structure. The magnetic powder is divided into individual units that can be independently controlled for optimal performance.
Solution Approach 2:
The non-magnetic substance serves as an intermediary layer between magnetic particles, controlling the degree of magnetic coupling. This intermediary allows for optimized magnetic conductivity by providing a controlled gap that prevents excessive coupling and eddy current formation while still permitting necessary magnetic flux penetration.
3Object-affected harmful factors
If conventional absorbing materials are used to reduce electromagnetic interference, then electromagnetic waves are absorbed, but electromagnetic energy is lost and the quality factor decreases
Solution Approach 1:
The patent converts the harmful effect of electromagnetic waves into a beneficial shielding effect. Instead of absorbing and dissipating electromagnetic energy as heat, the magnetic sheet redirects and contains magnetic flux lines, preventing them from reaching sensitive components. The magnetic particles create flux paths that guide electromagnetic energy away from interfering areas, transforming potential energy loss into useful magnetic shielding.
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 significantly decreases magnetic loss and improves the quality factor of the NFC magnetic sheets, leading to enhanced communication performance by reducing eddy current losses and increasing the real part of permeability while maintaining a high real-to-imaginary permeability ratio.
Implementation Method 1
The metal parts absorb the electromagnetic waves emitted by the reader-writer and then lose them in the form of eddy, thereby greatly reducing the electromagnetic waves through the antenna
Implementation Method 2
A wave absorbing magnetic sheet attached onto the antenna can absorb magnetic lines of force near the antenna without passing through the metal parts
Implementation Method 3
wave absorbing magnetic sheets for NFC antennas just absorb electromagnetic waves to converge the magnetic lines of force without any loss of the electromagnetic energy, which requires that the real part of the permeability is as large as possible and the imaginary part of the permeability is as small as possible
Data Source
AI summary
A paste for an NFC magnetic sheet is provided, which comprises: a magnetic powder; an organic carrier; and a nanoscale alumina powder; wherein a weight ratio of the nanoscale alumina powder to the magnetic powder ranges from about 0.0005 to about 0.005. A method of preparing the paste for the NFC magnetic sheet and an NFC magnetic sheet are also provided.