Dielectrophoretic Composite Insulator for Thermal Conductivity
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Solution Overview
Problem
Current insulating materials used in power electronic devices face challenges with thermal conductivity, as polymer materials have low thermal conductivity, and hexagonal boron nitride sheets exhibit anisotropy, leading to uneven thermal conductivity enhancement and mechanical property degradation, while traditional filler blending methods struggle to control in-plane and through-plane thermal conductivity effectively.
Innovation Solution
A composite insulating material is prepared using dielectrophoretic force orientation, where dielectric composite microspheres with a hexagonal boron nitride shell are arranged along an electric field direction, enhancing both in-plane and through-plane thermal conductivity by filling gaps with hexagonal boron nitride sheets, thereby improving mechanical properties and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a significant filler ratio of hexagonal boron nitride sheets is used to enhance thermal conductivity, then through-plane thermal conductivity is improved, but in-plane thermal conductivity becomes excessively high due to anisotropy and mechanical properties deteriorate
Solution Approach 1:
The patent segments the filler system into two distinct components: hexagonal boron nitride sheets for through-plane thermal conductivity and spherical fillers for in-plane thermal conductivity. This segmentation allows each filler type to contribute optimally to its designated thermal conduction direction without the negative effects of excessive filler ratios in a single-component system.
Solution Approach 2:
The patent applies local quality by assigning different filler types to different spatial orientations and functional requirements. Hexagonal boron nitride sheets are specifically utilized to enhance through-plane thermal conductivity where high thermal conduction is critical, while spherical fillers provide in-plane thermal conductivity and mechanical reinforcement, creating localized optimization of material properties throughout the composite structure.
2Ease of manufacture
If traditional filler blending and stirring method is used, then manufacturing simplicity is maintained, but synergistic enhancement of in-plane and through-plane thermal conductivity cannot be controlled
Solution Approach 1:
The patent employs preliminary action by pre-assembling hexagonal boron nitride sheets onto spherical filler surfaces before blending into the polymer matrix. This pre-assembly creates composite filler units with predetermined thermal conduction pathways, ensuring that when these units are distributed in the matrix, they automatically provide controlled synergistic enhancement of both in-plane and through-plane thermal conductivity without requiring complex post-processing alignment.
Solution Approach 2:
The patent creates a hierarchical composite material structure where hexagonal boron nitride sheets are combined with spherical fillers to form composite filler units. This composite approach allows the integration of different filler geometries and thermal conduction characteristics into a single functional unit that delivers controlled thermal enhancement in multiple directions while maintaining manufacturing simplicity.
3Ease of operation
If 0-dimensional spherical fillers are used during curing process, then ease of processing is maintained, but thermal conductivity is limited by deposition at the bottom of the matrix due to gravity
Solution Approach 1:
The patent replaces the gravity-driven settling mechanism with an electric field-based alignment system. By applying an external electric field during the curing process, the composite filler units with attached hexagonal boron nitride sheets are oriented according to the field direction rather than settling randomly or accumulating at the bottom due to gravity. This substitution of the governing physical mechanism ensures uniform distribution and controlled orientation, maximizing thermal conductivity while maintaining ease of processing.
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
This method achieves synergistic enhancement of in-plane and through-plane thermal conductivity, reduces thermal resistance, and maintains mechanical properties, addressing the limitations of traditional methods by ensuring uniform filler distribution and efficient heat transfer.
Implementation Method 1
conducting dielectrophoretic force orientation on the dielectric composite microspheres in the composite substrate, so as to cause the dielectric composite microspheres to arrange along a direction of electric field
Implementation Method 2
gaps between the dielectric composite microspheres in the composite insulating material are filled with the hexagonal boron nitride sheet
Data Source
AI summary
A composite insulating material based on dielectrophoretic force orientation and its preparation method are provided. The method includes: S1, preparing dielectric composite microspheres with a dielectric epoxy resin as a core and a hexagonal boron nitride sheet as a shell; S2, dispersing the hexagonal boron nitride sheet and the dielectric composite microspheres in an organic solvent to obtain a dispersion liquid, and adding an epoxy resin, an epoxy resin curing agent, and an epoxy resin accelerator to the dispersing liquid, and evaporating the organic solvent to obtain a composite substrate; S3, pouring the composite substrate into a container, wherein an upper surface and a lower surface of the container are connected with electrodes, respectively, transferring the container to a vacuum oven, and connecting a power supply of the container to adjust a voltage amplitude and a frequency of the electrodes, conducting dielectrophoretic force orientation on the dielectric composite microspheres in the composite substrate, so as to cause the dielectric composite microspheres to arrange along a direction of electric field; S4, increasing a temperature of the container to cure the composite substrate, cutting off the power supply to the container after curing, and obtaining the composite insulating material.