Aluminum-Silicon Carbide Composite Peripheral Ceramic Fiber Reinforcement
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Solution Overview
Problem
Aluminum-silicon carbide composites used as power-module base plates face issues with thermal expansion coefficient differences leading to stress, warping, and cracking, which affect heat dissipation and reliability, especially when used with ceramic circuit boards.
Innovation Solution
An aluminum-silicon carbide composite with an aluminum-ceramic fiber composite periphery, where ceramic fibers are integrated to reduce thermal expansion coefficient differences and enhance mechanical strength, improving shape stability and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aluminum-silicon carbide composite is used as a base plate to match the thermal expansion coefficient of circuit boards, then thermal expansion compatibility is improved, but the material exhibits inferior workability and increased cost due to compositing
Solution Approach 1:
The patent applies local quality by creating a composite structure where only specific regions (peripheral portions) contain ceramic fibers, while other regions maintain the base aluminum-silicon carbide composite properties. This localized approach allows the peripheral areas to have enhanced mechanical strength for workability, while the overall structure maintains thermal expansion compatibility with circuit boards.
Solution Approach 2:
The patent uses composite materials by integrating ceramic fibers into the aluminum-silicon carbide composite matrix. This creates a multi-phase material system that combines the thermal expansion benefits of silicon carbide with the mechanical strength and workability advantages of ceramic fiber-reinforced aluminum alloy regions.
2Manufacturing precision
If high-precision shape working and screw-hole working are performed on the aluminum-silicon carbide composite, then functional requirements are met, but the compositing of silicon carbide causes inferior workability and increased cost
Solution Approach 1:
The patent creates regions with different material properties where peripheral portions contain ceramic fibers for enhanced workability, while central portions maintain the base composite structure. This allows different regions to be optimized for different functions: workability in peripheral areas and thermal performance in central areas.
Solution Approach 2:
The patent incorporates ceramic fibers into the peripheral portions before the final working processes. This preliminary reinforcement ensures that when shape working and screw-hole working are performed, the peripheral regions have sufficient mechanical strength to prevent cracking, thereby enabling high-precision manufacturing.
3Ease of manufacture
If peripheral aluminum alloy portions are used to improve workability, then ease of working is improved, but thermal expansion coefficient difference from the aluminum-silicon carbide composite causes residual stress and cracking
Solution Approach 1:
The patent uses composite materials by integrating ceramic fibers into the aluminum alloy peripheral portions. This creates a hybrid material that combines the low thermal expansion coefficient of ceramic fibers with the workability of aluminum alloy, allowing peripheral regions to be easily worked while maintaining thermal expansion compatibility with the central aluminum-silicon carbide composite.
Solution Approach 2:
The patent modifies the thermal expansion coefficient parameter of the peripheral aluminum alloy portions by adding ceramic fibers. This changes the material properties of the peripheral regions to better match the thermal expansion characteristics of the central composite, thereby reducing thermal stress and preventing cracking during temperature cycling.
4Temperature
If the aluminum-silicon carbide composite is subjected to repeated thermal cycling, then heat dissipation function is maintained, but thermal stress generates warping and depressions that lower adhesion and reduce thermal conductivity
Solution Approach 1:
The patent employs composite materials with ceramic fibers distributed throughout the aluminum matrix, creating a multi-phase structure that combines the low thermal expansion coefficient of ceramic with the high thermal conductivity and ductility of aluminum. This composite structure maintains shape stability during thermal cycling while preserving heat dissipation capabilities.
Solution Approach 2:
The patent modifies the thermal and mechanical parameters of the base material by incorporating ceramic fibers. This changes the overall thermal expansion coefficient and mechanical strength parameters of the composite, enabling it to withstand repeated thermal cycling without warping or losing adhesion, thereby maintaining both heat dissipation and shape stability.
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 integration of ceramic fibers in the aluminum-silicon carbide composite reduces thermal expansion coefficient differences, enhances mechanical strength, and improves heat dissipation, making it suitable for high-reliability power-module base plates with reduced warping and cracking.
Implementation Method 1
an aluminum-silicon carbide composite having, on a periphery excluding both main surfaces of a first phase comprising a flat plate-shaped aluminum-silicon carbide composite having a plate thickness of 2 to 6 mm formed by impregnating, with a metal containing aluminum, a porous silicon carbide molded body
Data Source
AI summary
To provide an aluminum-silicon carbide composite which is suitable for use as a power-module base plate. An aluminum-silicon carbide composite wherein a peripheral portion having, as a main component thereof, an aluminum-ceramic fiber composite containing ceramic fibers having an average fiber diameter of at most 20 μm and an average aspect ratio of at least 100, is provided on the periphery of a flat plate-shaped aluminum-silicon carbide composite having a plate thickness of 2 to 6 mm formed by impregnating, with a metal containing aluminum, a porous silicon carbide molded body having a silicon carbide content of 50 to 80 vol %, and wherein the proportion of the aluminum-ceramic fiber composite occupied in the peripheral portion is at least 50 area %.