Boron Nitride Sintered Body With Isotropic Heat-Conducting Paths
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Solution Overview
Problem
The increasing integration density of electronic components demands a heat dissipation member with enhanced thermal conductivity, which existing boron nitride-based solutions have not adequately addressed due to anisotropy in thermal conductivity and insufficient heat dissipation performance.
Innovation Solution
A boron nitride sintered body comprising coarse particles with lengths of 20 µm or more, intersecting with fine particles, forms a mesh-like heat-conducting path, reducing anisotropy and increasing thermal conductivity, while a composite body with a resin-filled porosity achieves both high thermal conductivity and electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only fine particles are used in the boron nitride sintered body, then the manufacturing precision and density are improved, but the thermal conductivity is insufficient
Solution Approach 1:
The patent applies local quality by creating regions with different particle sizes throughout the sintered body. Coarse particles (20-200 μm) are distributed within a matrix of fine particles (1-20 μm), with coarse particles forming heat-conducting paths in specific regions while fine particles ensure dense packing and manufacturing precision in other regions. This spatial differentiation of particle sizes allows simultaneous achievement of high thermal conductivity and high density.
2Reliability
If coarse particles are used to increase thermal conductivity, then the heat dissipation performance is improved, but the anisotropy of thermal conductivity increases
Solution Approach 1:
The patent utilizes asymmetry in particle morphology and orientation. Coarse particles are specifically shaped with aspect ratios of 1.5 or more (length-to-width ratio), and their long axes are oriented in multiple directions rather than a single direction. This controlled asymmetry in shape and random orientation of multiple asymmetric particles creates isotropic thermal conductivity, preventing the anisotropy that would result from aligned asymmetric structures.
Solution Approach 2:
The patent transitions from two-dimensional planar heat conduction to three-dimensional volumetric heat conduction by distributing elongated coarse particles throughout the volume of the sintered body. The coarse particles extend in multiple spatial dimensions with random orientations, creating heat-conducting paths in three dimensions rather than along a single plane or direction, thereby achieving isotropic thermal properties.
3Reliability
If the particle size is increased to form heat-conducting paths, then the thermal conductivity is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the particle population into distinct size categories (coarse particles of 20-200 μm and fine particles of 1-20 μm) that can be independently processed and controlled. This segmentation allows each particle size fraction to be optimized separately for its specific function (thermal conduction vs. density), simplifying the overall manufacturing process compared to attempting to achieve both functions with a single particle size distribution.
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 boron nitride sintered body and composite body exhibit significantly improved thermal conductivity and reduced anisotropy, effectively addressing the need for enhanced heat dissipation in electronic components, with the composite body providing excellent electrical insulation and thermal performance.
Implementation Method 1
a heat-conducting path by the plurality of coarse particles is formed, and the anisotropy of the thermal conducting properties is decreased, so that the thermal conductivity can be sufficiently increased
Implementation Method 2
the contact area between the boron nitride particles can be sufficiently increased. Hence, the thermal conductivity can be further increased
Implementation Method 3
the composite body having the boron nitride sintered body and a resin filled in at least some of the pores thereof... has both an excellent thermal conductivity and excellent electrical insulation properties
Data Source
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AI summary
Provided is a boron nitride sintered body including: a plurality of coarse particles each having a length of 20 µm or more; and fine particles smaller than the plurality of coarse particles, in which, when viewed in a cross-section, the plurality of coarse particles intersect with each other. Provided is a method for manufacturing a boron nitride sintered body, the method including: a raw material preparation step of firing a mixture containing boron carbonitride and a boron compound in a nitrogen atmosphere to obtain lump boron nitride having an average particle diameter of 10 to 200 µm; and a sintering step of molding and heating a blend containing the lump boron nitride and a sintering aid to obtain a boron nitride sintered body including coarse particles each having a length of 20 µm or more in a cross-section and fine particles smaller than the coarse particles.