CNT Laminated Shielding Sheet for Lightweight EM Reflection Control

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Solution Overview

Problem

Existing materials fail to effectively reduce both transmission and reflection of electromagnetic waves while maintaining a lightweight structure.

Innovation Solution

An electromagnetic shielding laminated sheet comprising an electromagnetic wave absorbing layer with carbon nanotubes dispersed in a matrix and a metal layer, where the absorbing layer has a bulk density of 997 kg/m3 or less, allowing for multiple reflections and attenuations of electromagnetic waves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal layer is used for electromagnetic shielding, then shielding effectiveness is improved, but weight increases

Engineering Contradiction:

Improveshielding effectivenessVSAvoidweight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent uses a composite structure combining a metal layer with a low-density electromagnetic wave absorbing layer (bulk density ≤ 997 kg/m³). This composite material approach allows the metal layer to provide reflection-based shielding while the absorbing layer provides absorption-based shielding, achieving superior overall shielding effectiveness with reduced total weight compared to solid metal shielding of equivalent thickness.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different materials with different shielding mechanisms at different layers: the metal layer provides high-density reflection shielding, while the low-density absorbing layer provides absorption shielding. This local differentiation of material properties optimizes the overall shielding performance while minimizing weight, as each layer performs its specific function most effectively.

Inventive Principle:

Principle #3Local quality

2Reliability

If a dense metal structure is used for shielding, then shielding effectiveness is improved, but the structure becomes heavier

Engineering Contradiction:

Improveshielding effectivenessVSAvoidweight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent combines a metal layer with a low-density electromagnetic wave absorbing layer to create a composite shielding structure. The metal layer provides reflection-based shielding effectiveness, while the absorbing layer (with bulk density ≤ 997 kg/m³) provides absorption-based shielding with significantly reduced weight, achieving both high shielding effectiveness and light weight.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The electromagnetic wave absorbing layer is designed with low bulk density (≤ 997 kg/m³), suggesting a porous or foam-like structure. This porous material approach maintains shielding effectiveness through electromagnetic wave absorption while dramatically reducing the weight compared to solid metal structures of equivalent dimensions.

Inventive Principle:

Principle #31Porous materials

3Reliability

If traditional shielding materials are used, then electromagnetic wave blocking is achieved, but transmission and reflection reduction is insufficient

Engineering Contradiction:

Improveelectromagnetic wave blockingVSAvoidtransmission and reflection of electromagnetic waves

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a composite structure with a metal layer and a low-density absorbing layer, each providing different shielding mechanisms. The metal layer primarily reflects electromagnetic waves, while the absorbing layer absorbs them, creating a dual-mechanism shielding system that effectively reduces both transmission and reflection of electromagnetic waves across a broad frequency range.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent specifies that the electromagnetic wave absorbing layer has a bulk density equal to or less than 997 kg/m³, which is a critical parameter change from traditional dense shielding materials. This parameter optimization enables the absorbing layer to effectively attenuate electromagnetic waves through absorption while maintaining light weight, thereby reducing both transmission and reflection harmful effects.

Inventive Principle:

Principle #35Parameter changes

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 laminated sheet efficiently reduces transmission and reflection of electromagnetic waves, particularly in the milli-wave and microwave bands, while maintaining a lightweight design, suitable for applications in aviation, space exploration, and electronic equipment.

Implementation Method 1

an electromagnetic wave absorbing layer which includes a matrix and carbon nanotubes dispersed in the matrix and which has a bulk density equal to or less than 997 kg/m3

Methodology Applied

Scientific EffectElectromagnetic wave absorption: Absorption (EM radiation)

Implementation Method 2

a metal layer laid on top of the electromagnetic wave absorbing layer

Methodology Applied

Scientific EffectElectromagnetic reflection: Reflection

Data Source

PatentUS12520463B2Electromagnetic shielding laminated sheet

Publication Date: 2026.01.06 PANASONIC HOLDINGS CORP

AI summary

An electromagnetic shielding laminated sheet includes: an electromagnetic wave absorbing layer which includes a matrix and carbon nanotubes dispersed in the matrix and which has a bulk density equal to or less than 997 kg/m3; and a metal layer laid on top of the electromagnetic wave absorbing layer.