Quartz Resonator Pad Electrode Layout to Prevent Peeling
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Solution Overview
Problem
The existing quartz crystal resonator elements with AT cut quartz crystal substrates face challenges in securing sufficient thickness for metal films on inclined sections, leading to weak pad electrodes that can peel easily, which deteriorates the resonating characteristics, particularly the Drive Level Dependence (DLD) characteristic.
Innovation Solution
The resonator element design includes a quartz crystal substrate with a supporting section, a resonating section, and a coupling section, where the pad electrodes are strategically positioned on principal planes and side surfaces, ensuring they are separated from the outer edges to prevent peeling and enhance bonding strength, thereby improving the resonating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal film is formed on the inclined section to create pad electrodes, then the pad electrodes can be electrically coupled to the excitation electrodes, but the thickness of the metal film is insufficient and the pad electrodes peel easily
Solution Approach 1:
The pad electrode is extended from the inclined section onto the holding section, utilizing the additional dimensional space on the horizontal holding section surface. This allows the pad electrode to gain sufficient thickness and bonding area by transitioning to a different geometric plane where the metal film can be properly formed and bonded.
2Strength
If the pad electrode is positioned close to the outer edge of the inclined section for compact design, then the device size is reduced, but the pad electrode peels easily due to insufficient bonding area
Solution Approach 1:
The electrode structure is segmented into distinct functional regions: the inclined section for electrical coupling and the holding section for stable bonding. The pad electrode is divided between these sections, with the bonding portion positioned on the holding section away from the outer edge, ensuring sufficient bonding area while maintaining a relatively simple overall structure.
3Strength
If the metal film thickness is increased on the inclined section to prevent peeling, then the pad electrode strength is improved, but the manufacturing precision is compromised due to difficulty in securing sufficient thickness
Solution Approach 1:
The holding section acts as an intermediary platform between the inclined section and the external environment. It provides a stable, horizontal surface where the pad electrode can be formed with sufficient thickness and proper bonding characteristics, eliminating the need to increase metal film thickness on the difficult-to-manage inclined section.
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 effectively suppresses the peeling of pad electrodes and enhances the resonating characteristics, including the DLD characteristic, by increasing the contact area and reducing thermal stress, leading to improved handling and manufacturing ease while maintaining excellent temperature stability.
Implementation Method 1
an AT cut quartz crystal substrate and an electrode disposed on the surface of the quartz crystal substrate
Implementation Method 2
the quartz crystal substrate includes a resonating section
Data Source
AI summary
A resonator element includes a quartz crystal substrate including a supporting section, a resonating section, and a coupling section coupling the supporting section and the resonating section and having thickness smaller than the thickness of the supporting section, the supporting section including a first principal plane and a first side surface coupling the first principal plane and the coupling section, a first excitation electrode disposed in the resonating section, a second excitation electrode disposed in the resonating section and overlapping the first excitation electrode via the resonating section, and first and second pad electrodes including portions disposed on the first principal plane, the first and second pad electrodes being electrically coupled to the first and second excitation electrodes.