Layered SAW Substrate Grain Control for Crack Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The production of SAW devices often results in cracks in ceramic substrates, leading to decreased yield due to insufficient strength under thermal stress during the heat cycle process.
Innovation Solution
A ceramic substrate with a mean grain size of 0.5 μm to 15 μm and a standard deviation of grain sizes less than 1.5 times the mean, bonded to a piezoelectric substrate through Van der Waals force, to enhance strength and prevent crack formation.
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 cracks form during the heat cycle process due to insufficient strength
Solution Approach 1:
The patent applies parameter changes by precisely controlling the grain size of the ceramic substrate within the range of 0.5 μm to 15 μm. This specific grain size parameter range optimizes the balance between strength and manufacturability, preventing crack formation during heat cycle processes while maintaining production feasibility. The controlled grain size transforms the ceramic substrate's mechanical properties to resist thermal stress without compromising ease of manufacture.
2Temperature
If single-crystalline sapphire substrate is used as base substrate, then heat radiation performance is improved, but production cost increases
Solution Approach 1:
The patent changes the material parameter from single-crystalline sapphire to polycrystalline ceramic with specifically controlled grain size (0.5 μm to 15 μm). This parameter change maintains adequate heat radiation performance while dramatically reducing production cost, as polycrystalline ceramic is more economically manufacturable than single-crystalline sapphire.
Solution Approach 2:
The patent employs composite material strategy by using polycrystalline ceramic with optimized grain size distribution as the base substrate. This composite approach combines the benefits of cost-effectiveness with sufficient thermal performance, replacing expensive single-crystalline materials while maintaining the required heat radiation capabilities for SAW device operation.
3Ease of manufacture
If ceramic substrate with large grain size variation is used, then manufacturing is easier, but crack formation increases due to non-uniform stress distribution
Solution Approach 1:
The patent applies parameter changes by strictly controlling the grain size distribution of the ceramic substrate. By maintaining grain sizes within the 0.5 μm to 15 μm range, the patent achieves uniform stress distribution throughout the substrate during thermal cycling. This controlled parameter range prevents the non-uniform stress concentration that leads to crack formation, thereby improving reliability while preserving manufacturing ease.
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 described ceramic substrate effectively suppresses crack formation during the production process of SAW devices, ensuring higher yield and reliability by controlling grain size distribution and residual stress within specific ranges.
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 0.5 μm or more and less than 15 μm and the standard deviation of the grain sizes is less than 1.5 times the mean.