Ceramic Substrate Grain Control for Stronger SAW Bonding
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Solution Overview
Problem
The bonding strength between ceramic and piezoelectric substrates in SAW devices is insufficient, leading to separation issues during production, which increases production costs and decreases yield.
Innovation Solution
A ceramic substrate with a mean grain size of 15 μm to 40 μm and a standard deviation less than 1.5 times the mean, along with residual stress within the range of −300 MPa to 300 MPa, is used to enhance bonding strength between the ceramic and piezoelectric substrates through Van der Waals forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ceramic substrate with conventional grain size is used, then the production cost is reduced, but the bonding strength between ceramic and piezoelectric substrates is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the grain size of the ceramic substrate to a specific range (15-40 μm mean grain size with standard deviation less than 1.5 times the mean). This parameter optimization enables sufficient bonding strength through Van der Waals forces while maintaining cost-effectiveness compared to single-crystalline sapphire substrates.
2Strength
If the grain size of polycrystalline ceramic is not controlled, then the manufacturing process is simplified, but the bonding strength becomes insufficient leading to separation during production
Solution Approach 1:
The patent implements parameter changes by establishing specific grain size parameters (mean of 15-40 μm and standard deviation less than 1.5 times the mean) for the polycrystalline ceramic. These controlled parameters ensure adequate bonding strength while providing clear manufacturing specifications for producing consistent ceramic substrates.
3Reliability
If a ceramic substrate with inconsistent grain size is used, then the production process is simpler, but the bonding reliability decreases due to separation issues
Solution Approach 1:
The patent applies parameter changes by controlling both the mean grain size (15-40 μm) and the uniformity (standard deviation less than 1.5 times the mean). This dual parameter control ensures reliable bonding performance while maintaining manufacturability through well-defined production parameters.
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 configuration ensures a sufficient bonding strength between the ceramic and piezoelectric substrates, maintaining bonding even after heat cycles, thereby increasing production yield and reducing costs.
Implementation Method 1
a piezoelectric substrate and the ceramic substrate are bonded to each other through Van der Waals force
Data Source
AI summary
A ceramic substrate is formed of polycrystalline ceramic and has a supporting main surface. At the supporting main surface of the ceramic substrate, the mean of grain sizes of the polycrystalline ceramic is 15 μm or more and less than 40 μm and the standard deviation of the grain sizes is less than 1.5 times the mean.