Quartz Resonator Thickness Profile for Low ESR
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Solution Overview
Problem
Quartz crystal resonators with a clamped-clamped type four-point support structure face issues with increased equivalent series resistance due to vibration energy leakage and mounting stress, leading to frequency variations in temperature environments.
Innovation Solution
A resonator design with a substrate thickness increasing from the outer edge to the center, utilizing shorter first bonding members and longer second bonding members, and a non-connection area at the corner portions to reduce bonding material volume and distance between the vibrating region and bonding members, thereby minimizing vibration energy leakage and mounting stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If convex or bevel machining is applied to the piezoelectric resonator element to improve vibration and impact resistance, then the outer edge of the cross-sectional surface curves and the gap from the base attachment surface increases, but the amount of bonding material required increases and vibration energy leakage toward the base increases
Solution Approach 1:
The resonator element employs different thickness characteristics at different locations: the central region maintains a larger thickness to reduce vibration energy leakage, while the peripheral regions are thinned through convex or bevel machining to improve vibration and impact resistance. This local differentiation of structural properties resolves the contradiction between strength improvement and energy loss prevention.
2Strength
If the gap from the base attachment surface to the resonator element is increased due to convex or bevel machining, then vibration energy leakage increases, but the amount of bonding material required increases to ensure bonding strength
Solution Approach 1:
The resonator element is designed with non-uniform thickness distribution, maintaining larger thickness at the central vibrating region to minimize energy leakage while allowing peripheral thinning for mechanical strength. This local quality differentiation enables simultaneous achievement of bonding strength and energy conservation.
Solution Approach 2:
The patent adopts the convex or bevel shaped resonator element design from prior art (Document 1 or Document 2) but combines it with specific bonding member placement strategies to overcome the energy leakage problem, effectively copying the beneficial mechanical strength improvement while mitigating the harmful energy loss effect.
3Strength
If the volume of bonding material is increased to ensure bonding strength, then mounting stress increases and the equivalent series resistance value deteriorates
Solution Approach 1:
The patent optimizes the parameters of bonding members including their material composition, dimensions, and placement positions to achieve adequate bonding strength with minimal volume. By carefully controlling these parameters, the mounting stress is reduced to prevent deterioration of the equivalent series resistance value while maintaining necessary bonding strength.
4Reliability
If the distance between the vibrating region and bonding material is decreased to reduce bonding material volume, then bonding strength decreases, but the equivalent series resistance value improves
Solution Approach 1:
The resonator element is designed with differentiated thickness characteristics where the central vibrating region maintains larger thickness to reduce energy leakage, while peripheral regions are thinned to allow closer bonding member placement. This local quality differentiation enables reduced bonding material volume with maintained bonding strength, improving equivalent series resistance value.
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 design enhances bonding strength and electrical conductivity while reducing the equivalent series resistance and frequency variations in high-temperature and low-temperature environments, improving the stability of the resonator.
Implementation Method 1
a quartz crystal resonator element vibrating in a thickness-shear vibration mode as a vibration mode of the principal vibration
Implementation Method 2
a resonator element including a substrate gradually increasing in thickness from an outer edge toward a center
Data Source
AI summary
A resonator includes a resonator element including a substrate gradually increasing in thickness from an outer edge toward a center, excitation electrodes respectively disposed on both principal surfaces of the substrate, and a pair of electrode pads electrically connected to the excitation electrodes, disposed on at least one of the both principal surfaces, and disposed on one end side of the substrate, and a second substrate as a base, the pair of electrode pads are bonded to the second substrate via respective first bonding members, two places of the other end of the substrate on the opposite side to the one end are bonded to the second substrate via respective second bonding members, and a distance S1 between the two first bonding members, and a distance S2 between the two second bonding members fulfill S1<S2.