Conductive Syntactic Foam for EMI Shielding

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Solution Overview

Problem

Existing EMI shielding materials lack lightweight, multifunctional core materials with superior electrical conductivity and mechanical properties, particularly in syntactic foams, which are essential for modern electronic equipment designs that require both weight reduction and effective electromagnetic interference shielding.

Innovation Solution

The development of electrically conducting syntactic foams comprising a DGEBA-based epoxy resin matrix, functionalized multiwall carbon nanotubes, and hollow glass microspheres, with a process involving homogenous mixing and curing to achieve a lightweight, high-strength composite suitable for EMI shielding applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional EMI shielding materials are used, then electromagnetic interference shielding is provided, but the materials are heavy and lack multifunctional properties

Engineering Contradiction:
ImproveEMI shielding capabilityVSAvoidmaterial weight
Core Design Contradiction:
Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The invention uses a composite material system consisting of epoxy resin matrix, hollow glass microspheres, and carbon nanotubes. This composite structure provides EMI shielding capability while maintaining lightweight properties, as the hollow microspheres reduce density and carbon nanotubes provide conductivity without significant weight increase.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The syntactic foam composite serves multiple functions simultaneously: EMI shielding through carbon nanotube conductivity, structural support through the epoxy-resin-glass microsphere matrix, and lightweight properties through the hollow microsphere incorporation. This multi-functionality eliminates the need for separate shielding and structural components.

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

2Reliability

If carbon black is added to provide electrical conductivity, then EMI shielding is improved, but flame resistance becomes difficult to achieve

Engineering Contradiction:
Improveelectrical conductivityVSAvoidflame resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the type of conductive filler from carbon black to carbon nanotubes. This parameter change maintains electrical conductivity functionality while improving flame resistance, as carbon nanotubes have inherent thermal stability and do not contribute to flame propagation like carbon black does in polymeric matrices.

Inventive Principle:
Principle #35Parameter changes

3Strength

If conductive fibers are added to provide reinforcement, then EMI shielding is improved, but the composite becomes highly dense with poor moldability

Engineering Contradiction:
ImprovereinforcementVSAvoidmoldability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention incorporates hollow glass microspheres as porous lightweight filler materials in the composite matrix. These hollow spheres provide structural reinforcement and volume without significant weight increase, maintaining moldability while improving mechanical properties and EMI shielding capability through the embedded conductive network.

Inventive Principle:
Principle #31Porous materials

4Weight of moving object

If traditional syntactic foams are used, then lightweight and mechanical properties are achieved, but electrical conductivity is absent

Engineering Contradiction:
Improvelightweight propertyVSAvoidelectrical conductivity
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The invention merges the lightweight syntactic foam structure with conductive carbon nanotubes. The carbon nanotubes are dispersed throughout the epoxy resin matrix and hollow glass microsphere composite, creating a conductive network within the lightweight syntactic foam architecture, thus combining electrical conductivity with lightweight properties.

Inventive Principle:
Principle #5Merging (Combining)

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 resulting syntactic foams exhibit improved electrical conductivity, mechanical strength, and temperature resistance, making them suitable for use in lightweight core materials and filler applications, enhancing EMI shielding and structural integrity in electronic equipment.

Implementation Method 1

functionalized multiwall carbon nanotubes (0.5-20% by weight)... electrically conducting syntactic foam

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

resin matrix system (DGEBA based epoxy resin matrix)... functionalized carbon nanotubes... hollow glass microspheres

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentEP2242795B1Electrically conducting syntactic foam and a process for preparing the same
Publication Date: 2016.07.06 DIRECTOR GENERAL DEFENCE RES & DEV ORG

AI summary

The present invention relates to design and development of carbon nanotubes (CNT) reinforced electrically conducting synthetic foams comprising resin matrix system, carbon nanotubes, hollow glass microspheres and optionally hardener or catalyst for electrical conductivity and related applications especially electromagnetic interference (EMI) shielding.