Spherical Alumina Powder Balancing Alpha Phase and Surface Roughness
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Solution Overview
Problem
Existing spherical alumina powders with high α-phase percentage suffer from increased surface roughness after heat treatment, leading to decreased kneadability and thermal conductivity, and are prone to segregation in resin compositions, resulting in uneven thermal conductivity.
Innovation Solution
A method to produce spherical alumina powder with controlled α-phase percentage (60% to 100%) and particle surface roughness (1.14 to 1.35) by rapid cooling and washing followed by heat treatment at 1100 to 1300°C, maintaining high thermal conductivity and preventing segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical alumina is subjected to heat treatment to increase α-phase percentage, then thermal conductivity is improved, but surface roughness increases and kneadability into resin decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the heat treatment temperature range (1100-1300°C) and duration to achieve the desired α-phase percentage (60-100%) while limiting surface roughness increase. This optimized parameter combination resolves the contradiction by finding the optimal point where thermal conductivity is sufficiently improved without excessive roughness that would harm kneadability.
Solution Approach 2:
The patent creates a composite effect by combining spherical alumina particles with specific α-phase content and controlled surface roughness characteristics. This composite approach allows the material to simultaneously achieve high thermal conductivity from the α-phase alumina and adequate kneadability from the controlled surface morphology.
2Reliability
If spherical alumina powder is used with high filling percentage, then thermal conductivity of resin material is improved, but particle segregation occurs and uniformity decreases
Solution Approach 1:
The patent applies local quality by ensuring uniform distribution of spherical alumina particles with consistent surface roughness characteristics throughout the resin composition. The controlled surface roughness (1.14-1.35) creates uniform local interaction between particles and resin, preventing segregation and ensuring homogeneous thermal conductivity throughout the material.
Solution Approach 2:
The patent achieves homogeneity by producing spherical alumina particles with uniform size distribution (D50: 0.1-40 μm), consistent α-phase percentage (60-100%), and uniform surface roughness (1.14-1.35). This homogeneous particle population prevents segregation during mixing and curing, ensuring uniform thermal conductivity throughout the resin composition.
3Productivity
If particle size is decreased to improve filling properties, then fluidity is improved, but α-phase percentage decreases and thermal conductivity decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the heat treatment conditions (temperature: 1100-1300°C, atmosphere: air) specifically for fine particles (D50: 0.1-40 μm). This allows smaller particles to achieve high α-phase percentage (60-100%) that would normally be difficult to obtain at these sizes, thereby maintaining high thermal conductivity while enjoying the filling and fluidity benefits of smaller particle dimensions.
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 produced spherical alumina powder ensures high thermal conductivity and uniform distribution in resin compositions, enhancing the thermal performance of resin materials and electronic components.
Implementation Method 1
the thermal conductivity of the resin material filled with the spherical alumina is not high
Implementation Method 2
it is likely to settle in the resin composition kneaded and filled, and may undergo segregation
Data Source
AI summary
A spherical alumina powder, wherein D50 is 0.1 to 40 μm; a circularity is 0.90 or more and 1.00 or less; an α-phase percentage is 60% or more and 100% or less; and a particle surface roughness represented by Equation (1) below is 1.14 or more and 1.35 or less:Particle surface roughness=BET specific surface area A/sphere-equivalent specific surface area Sa calculated from particle size distribution.Equation (1)