Absorptive Thermal Composite With Selective Particle Coating
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Solution Overview
Problem
Existing thermally conductive and electromagnetically absorptive materials face a challenge in achieving high thermal conductivity while maintaining effective electromagnetic absorption, as high volume loading of thermally conductive particles reduces electromagnetic absorption due to increased reflectance.
Innovation Solution
A thermally conductive electromagnetically absorbing material is developed with a multimodal particle size distribution, where only a fraction (less than 1%) of thermally conductive particles are coated with an electromagnetically absorptive coating, achieving high thermal conductivity and electromagnetic absorptivity by reducing surface reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high volume loading of thermally conductive particles is used to achieve high thermal conductivity, then thermal conductivity is improved, but electromagnetic absorption deteriorates due to increased reflectance
Solution Approach 1:
The patent applies local quality by coating only a fraction (less than 1%) of the thermally conductive particles with electromagnetically absorptive material, rather than coating all particles uniformly. This localized application creates particles with asymmetric properties: most particles remain highly reflective and thermally conductive, while a small fraction provides electromagnetic absorption, thereby resolving the contradiction between thermal conductivity and electromagnetic absorption
Solution Approach 2:
The patent changes the parameter of coating coverage from 100% (conventional approach) to less than 1% of total particles. This drastic parameter change transforms the material's electromagnetic interaction by reducing overall reflectance while maintaining thermal conductivity pathways, simultaneously achieving both high thermal conductivity and effective electromagnetic absorption
2Object-affected harmful factors
If all thermally conductive particles are coated with electromagnetically absorptive coating to improve electromagnetic absorption, then electromagnetic absorptivity is improved, but thermal conductivity deteriorates
Solution Approach 1:
The patent applies partial action by coating only a small fraction (less than 1%) of the thermally conductive particles rather than all particles. This partial coating provides sufficient electromagnetic absorption (at least 5 dB/mm) while leaving the majority of particles uncoated to maintain thermal conductivity pathways, thereby resolving the contradiction between electromagnetic absorptivity and thermal conductivity
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 material achieves thermal conductivity of at least 2 W/(m-K) and electromagnetic absorptivity of at least 5 dB/mm in a specific frequency range, with reduced surface reflections due to the strategic coating of electromagnetically absorptive particles.
Implementation Method 1
The coating can include a dielectric loss mechanism and/or a conductor loss mechanism
Implementation Method 2
The coating can include a dielectric loss mechanism and/or a conductor loss mechanism
Implementation Method 3
The material can include a plurality of thermally conductive electromagnetically absorptive first particles and thermally conductive substantially electromagnetically non-absorptive second particles
Data Source
AI summary
A thermally conductive electromagnetically absorbing material includes a plurality of particles dispersed in a binder. The plurality of particles can have a particle size distribution having at least three peaks, where at least a majority of particles within a half width at half maximum of one, but not the other ones, of the at least three peaks are at least partially coated with an electromagnetically absorbing coating. The plurality of particles can include pluralities of first and second particles where a total number of the first particles is at most 1% of a total number of the first and second particles and where the first particles are more electromagnetically absorbing than the second particles. Films, molded articles and systems including the thermally conductive electromagnetically absorbing material are described.