Boron Nitride Fine Particles via Gas-Phase Synthesis
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Solution Overview
Problem
Current methods for producing submicron-order boron nitride fine particles result in low dispersability, high oxygen content, and poor crystallinity, which affects their thermal conductivity and lubrication capabilities, making them unsuitable for high-performance electronic components.
Innovation Solution
A gas-phase reaction method involving the introduction of ammonia and alkoxide borate at specific ratios in an inert atmosphere, followed by high-temperature heating, to produce boron nitride fine particles with controlled average particle diameter, graphitization index, and oxygen content, ensuring high purity and crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If boron nitride is obtained by high-temperature reactions between boron source and nitrogen source, then high purity boron nitride is produced, but the particles aggregate into large average particle diameter (a few μm to 20 μm) instead of submicron order
Solution Approach 1:
The invention segments the particle formation process into nucleation and growth stages by controlling reaction conditions. By maintaining specific temperature ranges (800-1350°C for precursor formation, then 1650-2200°C for crystallization) and using inert gas atmosphere, the process produces fine particles (0.05-2.0 μm) with controlled size distribution, preventing aggregation that occurs in conventional single-stage high-temperature reactions
Solution Approach 2:
The invention changes multiple parameters simultaneously: reaction temperature (two-stage heating), atmosphere (inert gas), reactant ratios (ammonia/alkoxide borate molar ratio of 1-5), and heating rate (within 30 seconds to reaction temperature). These parameter changes enable production of submicron-order particles with graphitization index ≤3 and oxygen content ≤0.20%, achieving both fine particle size and high crystallinity
2Manufacturing precision
If boron nitride particles are pulverized using jet mill to reduce particle size, then submicron order particles are obtained, but the active surface becomes extremely susceptible to oxidation resulting in high total oxygen content
Solution Approach 1:
The invention performs preliminary action by forming the boron nitride particles in an inert gas atmosphere during the synthesis process itself, rather than treating them after pulverization. The inert gas (nitrogen or argon) protects the active surface from oxidation during particle formation and cooling, preventing the formation of oxygen-containing groups on the particle surface
Solution Approach 2:
The invention converts the harmful effect of high reactivity (which normally causes oxidation) into a benefit by performing the synthesis in an inert atmosphere. The high reactivity of the active surface during formation is harnessed to create well-crystallized particles (graphitization index ≤3) while the inert atmosphere prevents oxidation, achieving low oxygen content (≤0.20%) in the final product
3Ease of operation
If boron nitride has thick scaly shape with large end surface area, then dispersability in resin is improved, but the aspect ratio increases making particle control difficult
Solution Approach 1:
The invention controls the aspect ratio by adjusting reaction parameters: temperature (800-1350°C for precursor, 1650-2200°C for crystallization), pressure (atmospheric or controlled), and reactant ratios (ammonia/alkoxide borate molar ratio of 1-5). These parameter changes produce particles with aspect ratio of 6.0 or less, achieving a balance between scaly morphology for dispersability and controlled dimensions for resin layer applications
4Ease of operation
If surface treatment using silane coupling agent is applied to improve dispersability, then inorganic powder dispersability is enhanced, but the treatment is ineffective for boron nitride due to surface functional groups on end surface alone
Solution Approach 1:
The invention performs preliminary action by optimizing the surface properties during particle formation through inert gas atmosphere synthesis. This produces particles with controlled surface functional groups and morphology (aspect ratio ≤6.0) that inherently provide good dispersability in resin, eliminating the need for subsequent silane coupling agent treatment which would be ineffective anyway due to the limited surface functional groups on boron nitride end surfaces
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 method achieves boron nitride fine particles with improved dispersability, low oxygen content, and high crystallinity, enhancing their thermal conductivity and lubrication capabilities, suitable for advanced electronic components.
Implementation Method 1
introducing ammonia and an alkoxide borate at an ammonia/alkoxide borate molar ratio of 1 to 5 in a reaction vessel in an inert gas atmosphere for heating at 800 to 1,350° C. within 30 seconds thereby obtaining a boron nitride precursor, and then heating the boron nitride precursor at 1,650 to 2,200° C. for at least 0.5 hour
Implementation Method 2
heating at 800 to 1,350° C. within 30 seconds thereby obtaining a boron nitride precursor, and then heating the boron nitride precursor at 1,650 to 2,200° C. for at least 0.5 hour
Implementation Method 3
heating the boron nitride precursor at 1,650 to 2,200° C. for at least 0.5 hour in an inert gas atmosphere, thereby scaly boron nitride fine particles are obtained
Data Source
AI summary
A boron nitride fine particle has low major diameter/thickness (aspect) ratio, high purity and high crystallinity, and also has an average particle diameter of 0.05 to 2.0 μm, a graphitization index of 3 or less, and a total oxygen content of 0.20% by mass or less, with an average value of a major diameter/thickness ratio of scaly particles being 6.0 or less. A method of producing a boron nitride fine particle includes introducing ammonia and an alkoxide borate at an ammonia/alkoxide borate molar ratio of 1 to 5 in a reaction vessel in an inert gas atmosphere for heating at 800 to 1,350° C. within 30 seconds thereby obtaining a boron nitride precursor, and then heating the boron nitride precursor at 1,650 to 2,200° C. for at least 0.5 hour in an inert gas atmosphere.