Flexible Soft Magnetic Core Using Embedded Ferromagnetic Wires

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Solution Overview

Problem

The fragility of ferrite cores in inductive devices and antennae leads to reduced magnetic permeability and inductance, making them unsuitable for applications requiring flexibility and durability, especially in RFID and NFC systems.

Innovation Solution

A flexible soft magnetic core composed of continuous ferromagnetic wires embedded in a polymeric medium, allowing flexibility in two orthogonal directions and maintaining magnetic properties under deformation, replacing traditional fragile ferrite cores.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional ferrite cores are used in inductive devices and antennas, then magnetic permeability and inductance are maintained, but the cores are fragile and prone to cracking under flexion and torsion

Engineering Contradiction:
Improvedurability of magnetic coreVSAvoidmechanical strength of magnetic core
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses composite materials by embedding ferromagnetic particles or wires within a flexible polymeric matrix. This combination provides both the magnetic properties needed for inductive devices and the mechanical flexibility to withstand deformation without cracking, directly resolving the contradiction between reliability and mechanical strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical state and composition of the magnetic core from solid ferrite to a composite structure with ferromagnetic elements dispersed in a polymeric medium. This parameter change enables the core to maintain magnetic permeability while gaining flexibility and resistance to mechanical failure under flexion and torsion.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If ferrite cores are protected by casting in resin or hard shell, then mechanical protection is improved, but the cores remain intrinsically fragile and can still crack

Engineering Contradiction:
Improveprotection of magnetic coreVSAvoidcomplexity of protection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the magnetic core material with the protective polymeric matrix into a single integrated composite structure. The ferromagnetic particles or wires are embedded within the flexible polymer, eliminating the need for separate protective shells or casting layers, thus reducing device complexity while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a flexible polymeric matrix as the protective medium that surrounds and protects the ferromagnetic elements. This flexible polymer provides mechanical protection while allowing the core to bend and deform without cracking, replacing rigid protective shells with a flexible alternative.

Inventive Principle:
Principle #30Flexible shells and thin films

3Power

If ferrite cores are used with high L/D ratio for increased inductance, then inductance is improved, but the cores become more susceptible to cracking and mechanical failure

Engineering Contradiction:
Improveinductance of antennaVSAvoidmechanical durability of core
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent employs composite materials with ferromagnetic particles or wires in a flexible polymeric matrix, enabling the creation of high L/D ratio cores that maintain both high inductance and mechanical durability. The flexible matrix prevents cracking even when the core is made thin and elongated for increased inductance.

Inventive Principle:
Principle #40Composite materials

4Adaptability or versatility

If metallic lamination stacks are used to replace ferrite, then flexibility is improved, but the low ohmic resistivity requires additional isolating layers increasing complexity

Engineering Contradiction:
Improveflexibility of magnetic coreVSAvoidcomplexity of isolating layers
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent uses a composite structure where ferromagnetic particles or wires are embedded in an intrinsically insulating polymeric matrix. This eliminates the need for additional isolating layers between metallic laminations, as the polymer itself provides both the flexible structure and the electrical insulation, reducing device complexity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The polymeric matrix serves multiple functions simultaneously: it provides the flexible structure, acts as the binding medium for ferromagnetic elements, and provides electrical insulation between conductive ferromagnetic components. This multi-functionality eliminates the need for separate isolating layers, reducing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 flexible core enhances durability and maintains magnetic performance, reducing the number of antennas needed and allowing for thinner, more efficient designs with higher flux density, thus improving the operational range and reliability of devices like RFID and NFC systems.

Implementation Method 1

said parallel magnetic paths being electrically isolated from each other by said polymeric medium

Methodology Applied
Scientific EffectDielectric isolation: Dielectric

Implementation Method 2

comprising a ferromagnetic material arranged to form parallel magnetic continuous paths within the core

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP3192084B1Flexible soft magnetic core, antenna with flexible soft magnetic core and method for producing a flexible soft magnetic core
Publication Date: 2020.01.08 PREMO SL
  • EP3192084B1 patent drawingFigure 1~2
  • EP3192084B1 patent drawingFigure 3~4
  • EP3192084B1 patent drawingFigure 5~6

AI summary

The flexible soft magnetic core (1) includes parallel continuous ferromagnetic wires (4) embedded in a core body (2) made of the polymeric medium (3). The continuous ferromagnetic wires (4) extend from one end to another end of said core body (2), are spaced apart from each other and are electrically isolated from each other by the polymeric medium (3). The method for producing the flexible soft magnetic core (1) comprises embedding continuous ferromagnetic wires (4) into an uncured polymeric medium (3) by means of a continuous extrusion process, curing the polymeric medium (3) with the continuous ferromagnetic wires (4) embedded therein to form a continuous core precursor (10), and cutting said continuous core precursor (10) into discrete magnetic cores (1).