Al-SiC Composite Heat Sink for Low Thermal Expansion
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Solution Overview
Problem
Conventional heat sink materials, such as copper and silicon carbide composites, face issues with high thermal expansion and low thermal conductivity, which affect the reliability of ceramic circuit boards and solder joints, and silicon carbide composites have limited thermal conductivity, necessitating a material with improved thermal conductivity and low thermal expansion.
Innovation Solution
An aluminum-silicon-carbide composite is developed with a silicon carbide content of 60 vol% or more, featuring specific particle diameter distributions (80-800 μm, 8-80 μm, and <8 μm) and an aluminum alloy with 10-14% silicon and 0.5-2.5% magnesium, impregnated into a porous silicon carbide molded body using an inorganic binder, achieving thermal conductivity of 230 W/mK or more and a coefficient of thermal expansion of 7.0 ppm/K or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If copper is used as heat sink material, then thermal conductivity is high, but coefficient of thermal expansion is high causing reliability problems
Solution Approach 1:
The invention uses a composite material consisting of silicon carbide particles dispersed in an aluminum alloy matrix. This composite structure combines the high thermal conductivity of aluminum with the low thermal expansion of silicon carbide, achieving both high thermal conductivity (200-400 W/mK) and low coefficient of thermal expansion (5-15 ppm/K), thereby resolving the contradiction between thermal conductivity and reliability.
2Reliability
If silicon carbide content is increased to decrease thermal expansion, then coefficient of thermal expansion decreases, but thermal conductivity remains insufficient
Solution Approach 1:
The invention optimizes multiple parameters simultaneously: silicon carbide particle size distribution (mixing fine particles <10 μm with coarse particles 10-500 μm), silicon carbide content (20-70 mass%), and aluminum alloy composition (adding magnesium 0.1-5 mass% and silicon 0.1-20 mass%). This multi-parameter optimization enables achieving both low thermal expansion coefficient (5-15 ppm/K) and high thermal conductivity (200-400 W/mK), resolving the contradiction between these two properties.
3Quantity of substance
If silicon carbide fine powder is added to increase silicon carbide content, then silicon carbide content increases, but particle diameter and amount must be precisely controlled to achieve high thermal conductivity
Solution Approach 1:
The invention applies local quality by creating a non-uniform particle size distribution within the composite. Fine silicon carbide particles (<10 μm) are used to fill interstices between coarse particles (10-500 μm), creating a dense packing structure. This local variation in particle size optimizes both the silicon carbide content (20-70 mass%) and thermal conductivity (200-400 W/mK), eliminating the need for precise control of single particle size while achieving high performance.
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 composite achieves high thermal conductivity, low thermal expansion, and low specific gravity, making it suitable for heat sink applications in power modules and semiconductor modules, while also being useful as a mounting material for moving apparatuses due to its low weight.
Implementation Method 1
The aluminum-silicon-carbide composite according to the present invention is formed by impregnating a porous silicon carbide molded body with an aluminum alloy
Data Source
AI summary
Provided are an aluminum-silicon-carbide composite having high thermal conductivity, low thermal expansion, and low specific gravity and a method for producing the composite. Provided is an aluminum-silicon-carbide composite formed by impregnating a porous silicon carbide molded body with an aluminum alloy. The ratio of silicon carbide in the composite is 60 vol % or more, and the composite contains 60-75 mass % of silicon carbide having a particle diameter of 80 μm or more and 800 μm or less, 20-30 mass % of silicon carbide having a particle diameter of 8 μm or more and less than 80 μm, and 5-10 mass % of silicon carbide having a particle diameter of less than 8 μm.