Quartz Resonator Assembly With Laser-Etched Sidewalls for Thermal Stability
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Solution Overview
Problem
Vibrating beam accelerometers face accuracy and precision issues due to thermally induced strains caused by differential thermal expansion between components, and wet-etching of quartz resonators results in asymmetric asperities and stress risers, leading to reduced quality factor and survivability under dynamic loading.
Innovation Solution
Selective laser etching of quartz resonators and vibrating beam accelerometers to form components with straight vertical side walls and monolithic proof mass assemblies from a single crystalline quartz substrate, eliminating the need for bonding materials and minimizing thermal expansion differences, thereby enhancing motion sensing accuracy and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet-etching is used to form quartz resonators, then the manufacturing process is simple, but asymmetric asperities and stress risers are created on side walls reducing quality factor and survivability
Solution Approach 1:
The patent replaces the chemical wet-etching process with a laser-based fabrication process. The laser precisely ablates the quartz substrate to form resonators with straight vertical side walls, eliminating the asymmetric asperities created by wet-etching. This substitution of mechanical/optical processing for chemical processing resolves the contradiction by achieving both manufacturing feasibility and superior surface quality.
Solution Approach 2:
The patent changes the fundamental processing parameter from chemical etching to laser ablation. By controlling laser parameters (power, pulse duration, scanning speed), the process achieves precise material removal with vertical side walls and minimal surface defects, transforming the manufacturing approach to eliminate the asperity formation inherent in wet-etching.
2Adaptability or versatility
If multiple materials are used in proof mass assembly, then component functionality is optimized, but differential thermal expansion causes thermally induced strains reducing accuracy
Solution Approach 1:
The patent applies homogeneity by forming the entire proof mass assembly, including resonators and proof mass, from a single monolithic quartz substrate. This eliminates material interfaces and differential thermal expansion, thereby eliminating thermally induced strains that would compromise measurement precision while maintaining all necessary component functionalities within the homogeneous quartz structure.
Solution Approach 2:
The patent merges multiple separate components (resonators, proof mass, supports) into a single integrated monolithic structure. By combining these elements into one homogeneous quartz piece through laser fabrication, the patent eliminates the thermal expansion mismatches that would arise from bonding different materials, thus preserving measurement accuracy while integrating all required functions.
3Ease of manufacture
If bonding materials are used to attach resonators to proof mass, then assembly is achieved, but thermal expansion differences and stress are introduced reducing robustness
Solution Approach 1:
The patent extracts and eliminates the bonding material from the assembly process. By fabricating the resonators and proof mass as a single monolithic quartz structure through laser processing, the patent removes the need for separate bonding materials that would introduce thermal expansion differences and interfacial stress, thereby enhancing thermal stability and overall robustness while maintaining assembly integrity.
4Manufacturing precision
If laser etching is used to form resonators, then straight vertical side walls are achieved improving quality factor, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex multi-step mechanical and chemical fabrication processes with a single laser ablation process. The laser directly writes the resonator structures into the quartz substrate with precise control over geometry, achieving straight vertical side walls without the need for masking, multiple etching steps, or post-processing, thereby reducing overall manufacturing complexity despite the advanced technology used.
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 solution improves the coupling between resonator tines, maintains balanced lateral motion, increases the quality factor, and enhances the survivability of resonators under dynamic loading, reducing frequency instability and thermal errors.
Implementation Method 1
selective laser etching a quartz substrate to reduce or eliminate asperities and unwanted crystal planes
Implementation Method 2
reduced and/or zero differences of coefficient of thermal expansion (CTE) between the components of the proof mass assembly
Data Source
AI summary
An example proof mass assembly includes a proof mass; a proof mass support; a flexure connecting the proof mass to the proof mass support, wherein the proof mass is configured to rotate relative to the proof mass support via the flexure; a first resonator connected to a first major surface of the proof mass and a first major surface of the proof mass support; and a second resonator connected to a second major surface of the proof mass and a second major surface of the proof mass support, wherein at least one of the proof mass, the proof mass support, the flexure, the first resonator, or the second resonator is formed by selective laser etching.