Porous SiC Composite Substrate for Stress-Relieved Machining
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Solution Overview
Problem
Conventional SiC composite substrates experience delamination, breaking, and cracking due to residual stress during machining processes like grinding and polishing.
Innovation Solution
A SiC composite substrate is designed with a biaxially-oriented SiC layer oriented in both the c-axis and a-axis directions, incorporating pores to mitigate residual stress, thereby reducing the likelihood of delamination, breaking, and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a SiC composite substrate is joined by integrating a thin SiC single-crystalline substrate with a SiC polycrystalline substrate, then cost is reduced and heat dissipation property is improved, but residual stress during machining causes delamination, breaking, and cracking
Solution Approach 1:
The patent introduces a porous layer between the SiC single-crystalline substrate and the SiC polycrystalline substrate. This porous layer acts as a stress-absorbing buffer that mitigates residual stress generated during machining operations such as grinding and polishing, thereby preventing delamination, breaking, and cracking while maintaining the cost-reduced composite structure
Solution Approach 2:
The porous layer serves as an intermediary element between the single-crystalline and polycrystalline substrates. It mediates the mechanical stress transfer during machining, absorbing excessive stress that would otherwise cause failure at the interface, thus improving reliability without compromising the manufacturing advantages
2Manufacturing precision
If the surface of the single-crystalline SiC substrate is polished, then surface quality is improved, but residual stress increases causing delamination and cracking
Solution Approach 1:
The porous layer is incorporated into the composite substrate structure before machining operations are performed. It provides pre-existing stress relief capacity that cushions against the residual stress generated during subsequent polishing and grinding operations, preventing delamination and cracking while allowing high surface quality to be achieved
Data Source
AI summary
Provided is a SiC composite substrate including a biaxially-oriented SiC layer in which SiC is oriented in both a c-axis direction and an a-axis direction, and a SiC polycrystalline layer provided on one surface of the biaxially-oriented SiC layer. Pores are present in the SiC composite substrate.