Hybrid Polymer EMI Shielding via Conductive Fillers
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Solution Overview
Problem
Conductive polymer materials face challenges in achieving low surface resistance and efficient electromagnetic interference (EMI) shielding due to high surface resistance and low interconnection efficiency between conductive filler particles, which complicates manufacturing and increases costs.
Innovation Solution
A hybrid polymer material comprising 0.01% to 1% carbon nanoparticles, 1% to 10% conductive polymeric material, and 1% to 20% electrically conductive fibers with a metallic surface, along with a nonconductive polymeric base, which reduces surface resistance and enhances interconnection for improved conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive filler material is embedded in nonconductive polymer matrix, then through-plane electrical conductivity is improved, but surface resistance increases
Solution Approach 1:
The patent applies composite materials by combining conductive polymer particles with traditional conductive fillers (metal fibers, carbon) in a nonconductive polymer matrix. This creates a multi-component composite that leverages the unique properties of each material: the conductive polymer provides surface conductivity while the metal fibers provide through-plane conductivity paths, resolving the contradiction between surface and bulk conductivity requirements.
Solution Approach 2:
The patent applies local quality by creating different conductivity characteristics in different regions of the material. The conductive polymer particles concentrate at or near the surface region to provide low surface resistance, while the metal fibers extend through the bulk to provide through-plane conductivity paths. This spatial differentiation of conductive elements allows simultaneous optimization of surface and bulk electrical properties.
2Reliability
If more conductive filler is added to improve conductivity, then electrical conductivity increases, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple conductive mechanisms into a single integrated material system. Instead of using separate layers or components for surface conductivity and bulk conductivity, the conductive polymer particles and metal fibers are combined within the same polymer matrix, creating a monolithic structure that provides both conductivity types simultaneously. This eliminates the need for additional manufacturing steps to assemble separate conductive elements.
Solution Approach 2:
By using a composite material approach with conductive polymer particles combined with traditional fillers, the patent achieves enhanced conductivity at lower overall filler loadings compared to using only traditional fillers. The conductive polymer particles form conductive networks more efficiently, reducing the amount of metal fiber or carbon needed and simplifying the formulation and processing of the conductive polymer composite.
3Reliability
If conductive filler particles are used, then electrical conductivity is achieved, but interconnection efficiency between particles is low
Solution Approach 1:
The conductive polymer particles act as intermediaries or mediators between the metal fiber conductive paths and the nonconductive polymer matrix. These polymer particles fill the gaps and voids between metal fibers, creating additional conductive pathways and improving the connectivity of the overall conductive network. This intermediary role enhances interconnection efficiency by bridging isolated conductive elements and reducing the percolation threshold.
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 hybrid polymer material achieves reduced surface resistance and increased EMI shielding effectiveness, allowing for weight reduction, simplified manufacturing, and effective EMI/RFI shielding without the need for metal shields.
Implementation Method 1
The combination of a conductive polymer in addition to conductive fillers allows improved connection between the network formed by the conductive filler particles
Implementation Method 2
For shielding applications, there needs to be transfer of charge from the inner conductive filler material to a ground connected to the surface of the conductive polymer material
Data Source
AI summary
An electrically conductive hybrid polymer material is described herein. The hybrid polymer material includes 0.01% to 1% by weight of carbon nanoparticles, 1% to 10% by weight of a conductive polymeric material, 1% to 20% of electrically conductive fibers having a metallic surface and 69% or more by weight of a nonconductive polymeric base material. The carbon nanoparticles may be carbon nanotubes, graphite nanoparticles, graphene nanoparticles, and/or fullerene nanoparticles. The conductive polymeric material may be an inherently conductive polymer, a radical polymers, or an electroactive polymer. The electrically conductive fibers may be stainless steel fibers, metal plated carbon fibers, or metal nanowires. The nonconductive polymeric base material may be selected from materials that are pliable at temperatures between −40° C. and 125° C. or materials that are rigid in this temperature range. The hybrid polymer material may be used to provide EMI shielding for wire cables of housings of electrical assemblies.