Perpendicular Ferrite Microwire Arrays for EMI Shielding

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Solution Overview

Problem

Existing electromagnetic interference (EMI) shielding technologies using carbonyl iron particles or perpendicularly aligned microwires in polymer matrices lack optimized magnetic properties, stability, and high areal density, making them unsuitable for application-specific needs and environmental exposure.

Innovation Solution

A method for fabricating polymeric sheets containing perpendicular, magnetic ferrite microwires by attaching them to a substrate, encapsulating in a non-conductive polymer, and detaching without removing from the substrate, allowing for flexible, high-density, and high-quality magnetic arrays for EMI and antenna shielding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If carbonyl iron particles are mixed into a polymer matrix for EMI shielding, then EMI shielding function is achieved, but magnetic properties are not optimized for application-specific needs

Engineering Contradiction:

Improvemagnetic property optimizationVSAvoidEMI shielding performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses carbonyl iron particles with specific morphology (needle-like structure) and controlled size distribution (0.5-5 μm length) to create localized magnetic properties within the polymer matrix. This allows optimization of magnetic response in specific regions while maintaining overall EMI shielding functionality, resolving the contradiction between adaptability and reliability.

Inventive Principle:

Principle #3Local quality

2Shape

If perpendicularly aligned microwires are encapsulated in polymer matrices, then structural organization is improved, but magnetic properties are lost

Engineering Contradiction:

Improvewire alignmentVSAvoidmagnetic property

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent creates a composite material system combining carbonyl iron particles with polymer matrix, where the iron particles retain their magnetic properties while being embedded in the polymer. This composite approach maintains both the structural organization of aligned particles and the magnetic functionality, resolving the contradiction between shape control and magnetic property preservation.

Inventive Principle:

Principle #40Composite materials

3Reliability

If iron nanowires in polyaniline are used, then magnetic properties are achieved, but air stability is lost

Engineering Contradiction:

Improvemagnetic propertyVSAvoidair stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses carbonyl iron particles which, while having finite stability, provide sufficient magnetic functionality for the application lifecycle. The particles are designed to maintain their magnetic properties and structural integrity throughout the intended service period, accepting controlled degradation rather than requiring indefinite stability, thus resolving the contradiction between magnetic performance and long-term stability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Quantity of substance

If iron oxide nanowires are chemically bonded to foil substrate, then high wire density is achieved, but flexibility and abrasion resistance are lost

Engineering Contradiction:

Improvewire densityVSAvoidflexibility

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent embeds carbonyl iron particles within a polymer matrix that forms a flexible shell or film structure. This matrix allows the high-density particle arrangement to be maintained while providing the flexibility and mechanical compliance needed for conformal mounting and resistance to abrasion, resolving the contradiction between density and adaptability.

Inventive Principle:

Principle #30Flexible shells and thin films

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 provides flexible, high-moment, low-coercivity magnetic arrays with optimized properties for superior EMI and antenna shielding, achieving directional anisotropy and stability, overcoming previous limitations in magnetic properties and areal density.

Implementation Method 1

perpendicularly aligned micrawires and/or nanowires encapsulated in polymer matrices

Methodology Applied

Scientific EffectMagnetic alignment: Magnetism

Implementation Method 2

encapsulating at least a portion of individual lengths of the micrawires in a non-conductive polymeric sheet

Methodology Applied

Scientific EffectEncapsulation: Physical Containment

Data Source

PatentUS11376804B2Microwire array devices and methods for fabricating polymeric sheets containing microwires

Publication Date: 2022.07.05 THE BOEING CO

AI summary

A method for fabricating polymeric sheets containing microwires includes encapsulating at least a portion of individual lengths of a plurality of microwires in a non-conductive polymeric sheet while the microwires are attached to the substrate. The microwires are then detached from the substrate without removing the microwires from the polymeric sheet. The detaching step forms a separated polymeric sheet containing the detached microwires. Individual detached microwires of the plurality are approximately perpendicular to the separated polymeric sheet. A microwire array device includes a non-conductive polymeric sheet and a plurality of microwires. Individual microwires of the plurality have an independent length at least partially encapsulated by the polymeric sheet, are approximately perpendicular to the polymeric sheet, and contain magnetic ferrite.