Piezoelectric Resonator Electrode Layout for Stable Frequency
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Solution Overview
Problem
Existing piezoelectric resonator units face issues with unstable frequency characteristics due to the influence of adhesion layer formation states and stress transmission, leading to defective connections between electrodes and reduced resonant frequency stability.
Innovation Solution
A piezoelectric resonator unit design featuring a piezoelectric layer with excitation electrodes and extended electrodes, substrates with adhesion layers and cut-away portions, and connection electrodes that stabilize electrode connections by forming on inclined portions of the adhesion layers, reducing defective formations and improving resonant frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal adhesion layer is used to bond the substrate and piezoelectric vibration plate, then bonding strength is improved, but stress transmission causes unstable frequency characteristics
Solution Approach 1:
The patent introduces a resin adhesion layer as an intermediary between the metal adhesion layer and the piezoelectric vibration plate. This resin layer acts as a stress isolation medium that prevents stress from the substrate from being transmitted to the piezoelectric element, thereby maintaining stable frequency characteristics while preserving the bonding strength provided by the metal adhesion layer.
2Ease of manufacture
If the adhesion layer formation state varies (dents or bulges), then manufacturing flexibility is improved, but connection electrode formation precision deteriorates
Solution Approach 1:
The patent performs preliminary actions by forming the metal adhesion layer and resin adhesion layer in sequence before forming the connection electrode. The metal adhesion layer is formed first to ensure strong bonding, followed by the resin adhesion layer that creates a stable surface. This preliminary layer formation ensures that even if the metal layer has irregularities, the subsequent connection electrode can be formed on a stable resin surface with precise thickness and area control.
3Adaptability or versatility
If the adhesion layer has irregular formation (dents or bulges), then manufacturing process tolerance is improved, but connection electrode area and thickness control deteriorates
Solution Approach 1:
The resin adhesion layer serves as an intermediary that decouples the irregularities of the metal adhesion layer from the connection electrode formation process. The resin layer provides a uniform surface that allows precise control of connection electrode thickness and area, while the underlying metal layer can have variations without affecting the electrode quality.
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 design stabilizes frequency characteristics, reduces defective connections, and enhances resonant frequency stability by simplifying the configuration and improving electrode connection stability, thereby reducing manufacturing costs and disconnection risks.
Implementation Method 1
a piezoelectric resonator including a piezoelectric layer
Data Source
AI summary
A piezoelectric resonator unit that includes: a piezoelectric resonator including a piezoelectric layer; a first substrate adjacent to a first principal surface of the piezoelectric layer; a first adhesion layer between the first substrate and the piezoelectric layer; a second substrate adjacent to a second principal surface of the piezoelectric layer; and a second adhesion layer between the second substrate and the piezoelectric layer. In plan view of the surface of the second substrate opposite from the piezoelectric layer, the second substrate includes a cut-away portion exposing an inclined portion of the second adhesion layer expanding toward an outer side portion of the second substrate and an extended end portion of an extended electrode on the piezoelectric layer. A connection electrode on the inclined portion of the second adhesion layer and the cut-away portion of the second substrate electrically connects an outer electrode and the extended end portion.