Anisotropic heat transfer, electromagnetic interference shielding composite and method for preparation thereof
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Solution Overview
Problem
Conventional EMI shielding materials lack flexibility, mechanical properties, and high thermal conductivity, often requiring high conductive filler content that leads to aggregation and poor processing properties, while lower filler content compromises conductivity and thermal efficiency.
Innovation Solution
An anisotropic composite formed by aligned polymer nanofibers with thermal conductive fillers and metal compounds, where specific planes of orientation provide high thermal conductivity and low electrical resistance, achieving efficient EMI shielding and heat dissipation without sacrificing mechanical properties or thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high content of conductive fillers is used to achieve high electrical conductivity and EMI shielding effectiveness, then EMI shielding property is improved, but mechanical properties and processing properties deteriorate due to filler aggregation
Solution Approach 1:
The conductive filler is segmented into individual nanowires that are uniformly distributed within the polymer matrix, preventing aggregation while maintaining high conductivity. The nanowire network is segmented into discrete conductive pathways rather than continuous filler clusters.
Solution Approach 2:
The polymer matrix exhibits different properties in different regions: areas with nanowire networks provide high electrical conductivity for EMI shielding, while other regions maintain the polymer's inherent mechanical flexibility and processability. The composite has locally optimized properties rather than uniform composition.
2Reliability
If high content of conductive fillers is used to achieve high electrical conductivity, then electrical conductivity is improved, but processing properties deteriorate due to filler aggregation
Solution Approach 1:
The conductive filler is segmented into individual nanowires that are uniformly distributed within the polymer matrix, preventing aggregation while maintaining high conductivity. The nanowire network is segmented into discrete conductive pathways rather than continuous filler clusters.
Solution Approach 2:
The invention uses a composite material system combining polymer matrix with conductive nanowire filler. This composite approach allows the polymer to provide processability while the nanowires provide conductivity, achieving both properties simultaneously without filler aggregation issues.
3Reliability
If conventional EMI shielding materials are used to achieve EMI shielding effectiveness, then EMI shielding property is improved, but flexibility and lightweight characteristics are lost
Solution Approach 1:
The EMI shielding material is formulated as a flexible polymer composite that can be bent and conform to surfaces. The thin film structure provides flexibility while the embedded nanowire network maintains electrical conductivity for EMI shielding, eliminating the rigidity of traditional metal-based shields.
Solution Approach 2:
The invention uses a composite material system combining polymer matrix with conductive nanowire filler. This composite approach allows the polymer to provide flexibility and light weight while the nanowires provide electrical conductivity for EMI shielding, achieving both properties simultaneously.
4Strength
If lower content of conductive fillers is used to maintain mechanical properties, then mechanical properties are preserved, but electrical conductivity is severely affected
Solution Approach 1:
The invention changes the parameter of filler morphology from conventional particles or short fibers to high aspect ratio nanowires. This parameter change allows achieving percolation and high conductivity at much lower filler loading, preserving mechanical properties while maintaining excellent electrical conductivity.
Solution Approach 2:
The invention uses a composite material system combining polymer matrix with conductive nanowire filler. This composite approach allows the polymer to provide mechanical integrity while the nanowires provide electrical conductivity, achieving both properties simultaneously without filler aggregation issues.
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 composite exhibits thermal conductivity of at least 110 W/mK along specific planes, comparable EMI shielding effectiveness to pure metal sheets, and maintains flexibility and mechanical integrity, making it suitable for diverse electronic applications.
Implementation Method 1
the thermal conductivity of the first plane of orientation of the polymer nanofibers has a thermal conductivity substantially the same as or similar to the thermal conductivity of the second plane, and the thermal conductivity of the first or second plane of orientation of the polymer nanofibers is at least 2-fold of the thermal conductivity of a third plane of orientation
Implementation Method 2
comparable EMI shielding effectiveness to that of the corresponding pure metal sheet of the first or second metal compound against electromagnetic waves
Data Source
AI summary
The present invention provides an anisotropic, thermal conductive, electromagnetic interference (EMI) shielding composite including a plurality of aligned polymer nanofibers to form a polymer mat or scaffold having a first and second planes of orientation of the polymer nanofibers. The first plane of orientation of the polymer nanofibers has a thermal conductivity substantially the same as or similar to that of the second plane, and the thermal conductivity of the first or second plane of orientation of the polymer nanofibers is at least 2-fold of that of a third plane of orientation of the polymer nanofibers which is about 90 degrees out of the first and second planes of orientation of the polymer nanofibers, respectively, while the electrical resistance of each of the first and second planes is at least 3 orders lower than that of the third plane. A method for preparing the present composite is also provided.