SiC-Magnesium Composite Heat Sink via Oxide Film Infiltration
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Solution Overview
Problem
Current composite materials for heat radiation members in semiconductor elements face challenges in achieving improved thermal characteristics, joint characteristics with cooling apparatuses, and larger sizes, with issues such as porosity, thermal conductivity, coefficient of thermal expansion, solderability, corrosion resistance, and manufacturing defects.
Innovation Solution
A magnesium-based composite material with low porosity, achieved through specific treatments of SiC and magnesium alloy, including oxidation treatment and pressurization steps, to enhance thermal conductivity and adaptability, and the use of high SiC content to match the coefficient of thermal expansion of semiconductor elements, along with methods for electroplating and large-scale manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infiltration temperature is raised to lower porosity, then porosity is reduced and thermal characteristics improve, but shrinkage cavities and gas holes occur during solidification
Solution Approach 1:
The patent changes the infiltration temperature parameter to a moderate range (650-750°C) that balances porosity reduction with prevention of solidification defects. This optimal temperature range allows sufficient molten metal fluidity to fill pores while avoiding excessive heat that causes shrinkage cavities and gas holes during cooling
Solution Approach 2:
The patent applies preliminary oxidation treatment to SiC particles before infiltration, forming a thin oxide layer that improves wettability between the molten magnesium alloy and SiC particles. This preliminary surface modification enables better infiltration at moderate temperatures, reducing porosity without requiring high temperatures that would cause defects
2Reliability
If infiltration temperature is raised to lower porosity, then porosity is reduced, but apparatus scale and cost increase
Solution Approach 1:
The patent optimizes the infiltration temperature to a moderate range (650-750°C) that achieves sufficient porosity reduction without requiring large-scale high-temperature heating apparatus. This parameter optimization allows use of simpler, smaller equipment while still achieving porosity below 3%
3Reliability
If non-metal inorganic material content is increased to lower coefficient of thermal expansion, then coefficient of thermal expansion is reduced, but manufacturing difficulty increases due to filling limitations
Solution Approach 1:
The patent changes the particle size distribution of SiC particles, using a mix of particle sizes that improve packing density and fillability. This allows achieving high SiC content (50-70 volume %) with good flow and filling characteristics during infiltration, while maintaining low coefficient of thermal expansion (4-8 ppm/K)
Solution Approach 2:
The patent creates a composite material system combining magnesium alloy matrix with high content SiC particles (50-70 volume %). This composite structure achieves the desired low coefficient of thermal expansion through high SiC content while the magnesium alloy matrix provides good infiltration and filling characteristics during manufacturing
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 solution results in a composite member with excellent thermal conductivity, low porosity, improved joint characteristics, and enhanced reliability as a heat radiation member, capable of larger sizes with reduced defects and increased commercial value.
Implementation Method 1
infiltrating the aggregate with magnesium or a magnesium alloy in a molten state
Implementation Method 2
excellent in thermal conductivity
Data Source
Figure 1(I)~2
Figure 3(I)~3(II)
Figure 4(I)~4(II)
AI summary
A composite member suitable for a heat radiation member of a semiconductor element and a method of manufacturing the same are provided. This composite member is a composite of magnesium or a magnesium alloy and SiC, and it has porosity lower than 3 %. This composite member can be manufactured by forming an oxide film on a surface of raw material SiC, arranging coated SiC having the oxide film formed in a cast, and infiltrating this coated SiC aggregate with a molten metal (magnesium or the magnesium alloy). The porosity of the composite member can be lowered by improving wettability between SiC and the molten metal by forming the oxide film. According to this manufacturing method, a composite member having excellent thermal characteristics such as a coefficient of thermal expansion not lower than 4 ppm/K and not higher than 10 ppm/K and thermal conductivity not lower than 180 W/m●K can be manufactured.