Support substrate, composite substrate, electronic device, and module
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Solution Overview
Problem
Existing single crystal sapphire support substrates in TC-SAW filters suffer from spurious signal reflection, hindering normal filtering performance, particularly in frequency bands above 3.5 GHz.
Innovation Solution
A polycrystalline support substrate with a specific proportion of small-angle grain boundaries (2° to 15°) and a uniform distribution, reducing longitudinal wave energy and spurious signal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If single crystal sapphire is used as support substrate, then thermal conductivity is improved, but spurious signal reflection increases
Solution Approach 1:
The patent uses polycrystalline sapphire as a composite material alternative to single crystal sapphire. The polycrystalline structure maintains the thermal conductivity benefits of sapphire while the multiple grain boundaries scatter acoustic waves, reducing spurious signal reflection. This resolves the contradiction by using a composite material form that combines the advantages of thermal performance with reduced harmful reflections.
Solution Approach 2:
The patent introduces grain boundaries with specific local characteristics (small-angle grain boundaries with misorientation angles of 2°-15°) into the sapphire substrate. These localized structural features act as acoustic wave scatterers at specific positions throughout the material, reducing spurious signal reflection while preserving the overall thermal conductivity of the sapphire substrate.
2Object-generated harmful factors
If polycrystalline material is used to reduce spurious signals, then spurious signal reflection is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for grain boundary characteristics: small-angle grain boundaries with misorientation angles of 2°-15° and a proportion of 1%-5% of total grain boundaries. By controlling these parameters within defined ranges, the patent achieves effective spurious signal reduction while providing clear manufacturing specifications that guide the production process.
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 substrate effectively suppresses spurious signals, enabling normal filtering performance in frequency bands above 3.5 GHz by minimizing signal reflection.
Implementation Method 1
the number of small-angle grain boundaries with a misorientation angle of 2° to 15° in the support substrate accounts for 1% to 5% of the total number of grain boundaries... effectively reduce the energy of longitudinal wave transmission
Data Source
AI summary
A support substrate, a composite substrate, an electronic device, and a module are provided, the support substrate is made of a polycrystalline material, a number of small-angle grain boundary with a misorientation angle of 2° to 15° in the support substrate accounts for 1% to 5% of a total number of grain boundaries, and the support substrate with the specific small-angle grain boundary proportion can effectively suppress spurious signals and ensure normal filtering.