Composite Substrate Edge Chipping Prevention via Beveling and Flush Grinding
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Solution Overview
Problem
The existing methods for manufacturing composite substrates with piezoelectric and supporting substrates bonded by an organic adhesive layer often result in chipping of the piezoelectric substrate's edge during lapping and polishing, due to incomplete adhesive application and increased distance between the substrates caused by beveling, which leads to poor bonding and potential contamination from the adhesive.
Innovation Solution
A method involving beveling the piezoelectric substrate, bonding it to a supporting substrate with an organic adhesive layer, grinding the peripheral surfaces to make them flush, and then lapping and polishing, ensuring the edge is bonded and resistant to chipping, while maintaining the initial outer diameter of the supporting substrate for consistent apparatus usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the piezoelectric substrate is beveled to prevent edge breakage during handling, then the edge strength is improved, but the distance between the piezoelectric substrate and supporting substrate increases causing incomplete adhesive application and poor bonding
Solution Approach 1:
The piezoelectric substrate is beveled in advance before bonding to prevent edge breakage during handling. This preliminary action ensures the edge has sufficient strength to withstand subsequent processing steps, while the bonding process is then optimized to accommodate the beveled geometry.
Solution Approach 2:
The bevel is applied only to the edge region of the piezoelectric substrate where mechanical strength is needed, while the central bonding surface maintains its original geometry to ensure proper adhesive contact and bonding quality. This localized modification allows both edge strength and bonding quality to be optimized simultaneously.
2Volume of moving object
If the thickness of the piezoelectric substrate is decreased to reduce device size, then the device compactness is improved, but the edge becomes more susceptible to chipping during lapping
Solution Approach 1:
The piezoelectric substrate is beveled in advance before bonding to prevent edge breakage during handling. This preliminary action ensures the edge has sufficient strength to withstand subsequent processing steps, while the bonding process is then optimized to accommodate the beveled geometry.
Solution Approach 2:
The organic adhesive layer is applied to extend beyond the beveled edge of the piezoelectric substrate, creating a cushioning effect that compensates for the reduced edge strength due to thinning. This beforehand cushioning prevents chipping during lapping by providing structural support to the vulnerable thin edges.
3Reliability
If the organic adhesive layer is applied to cover the beveled edge to prevent chipping, then the edge protection is improved, but the adhesive may detach and attach as contaminant to the surface
Solution Approach 1:
The organic adhesive layer is applied selectively: it extends beyond the beveled edge to provide protection during lapping, but is then precisely removed from the front surface area where electrodes will be formed. This localized presence and removal of adhesive ensures edge protection without surface contamination.
Solution Approach 2:
The organic adhesive layer is removed from the front surface of the piezoelectric substrate after bonding and before electrode formation. This extraction eliminates the risk of adhesive detachment and contamination while preserving the protective effect on the edges during the lapping process.
4Manufacturing precision
If the peripheral surface is ground to make surfaces flush to prevent adhesive detachment, then the surface finish is improved, but the initial outer diameter of the supporting substrate must be maintained requiring precise grinding control
Solution Approach 1:
The grinding process is controlled by using the initial outer diameter of the supporting substrate as a reference dimension. By maintaining this diameter throughout the process, the system provides built-in feedback control that ensures the peripheral surfaces of all layers become flush without requiring complex measurement and adjustment systems.
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
This approach prevents chipping of the piezoelectric substrate's edge and ensures the organic adhesive layer does not detach as a contaminant, improving surface finishing and reducing frequency variations in temperature changes, thereby enhancing the reliability and performance of the composite substrate.
Implementation Method 1
bonding the piezoelectric substrate to the supporting substrate with an organic adhesive layer interposed therebetween
Implementation Method 2
placing abrasive grains between a surface of a piezoelectric substrate and a lapping plate, and lapping the surface of the piezoelectric substrate with the lapping plate
Data Source
AI summary
A supporting substrate and a piezoelectric substrate are prepared. A surface of the supporting substrate is bonded to the backside of the piezoelectric substrate with an organic adhesive layer interposed therebetween to form a laminated substrate. Subsequently, a peripheral surface of the laminated substrate is ground such that a peripheral surface of the piezoelectric substrate, a peripheral surface of the organic adhesive layer, and a peripheral surface of the supporting substrate on the side of the organic adhesive layer are made flush with each other. Subsequently, the surface of the piezoelectric substrate is polished to reduce the thickness of the piezoelectric substrate and performing mirror polishing of the surface.