Acoustic Wave Cavity Structure to Minimize Capacitive Coupling
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Solution Overview
Problem
Conventional elastic wave devices experience capacitive coupling between conductive walls and sealing frames, leading to potential malfunctions and reduced performance.
Innovation Solution
The acoustic wave device incorporates an insulating layer with a recess and a piezoelectric layer defining a cavity, featuring first and second excitation electrodes, frames with varying widths, and a tapered shape to minimize capacitive coupling, along with dielectric layers and wiring electrodes to enhance structural integrity and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conductive wall and sealing frame are used in the acoustic wave device, then structural integrity is improved, but capacitive coupling occurs between the conductive wall and sealing frame causing malfunction
Solution Approach 1:
An insulating layer is introduced as an intermediary between the conductive wall and the sealing frame. This insulating layer prevents direct electrical contact between the two conductive components, thereby eliminating capacitive coupling while maintaining the structural integrity provided by the conductive wall and sealing frame assembly.
Solution Approach 2:
The harmful capacitive coupling effect is extracted or removed from the system by introducing the insulating layer. The insulating layer effectively extracts the electrical interaction between the conductive wall and sealing frame, allowing them to coexist structurally without the harmful electrical coupling.
2Use of energy by moving object
If the piezoelectric layer is made thicker to enhance piezoelectric effect, then energy conversion is improved, but device height increases causing integration difficulties
Solution Approach 1:
The piezoelectric layer is constructed as a composite structure with alternating layers of high piezoelectric coefficient material and low piezoelectric coefficient material. This composite arrangement enhances the overall piezoelectric effect and energy conversion efficiency while maintaining a compact thickness, as the high-performance layers are distributed throughout the structure rather than requiring a single thick layer.
Solution Approach 2:
The piezoelectric layer is segmented into multiple alternating layers with different piezoelectric coefficients. This segmentation allows the high piezoelectric coefficient layers to be distributed throughout the structure, maximizing energy conversion efficiency without requiring a large overall thickness, thus resolving the conflict between energy conversion and device height.
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 effectively reduces capacitive coupling, enhances structural stability, and improves the operational reliability of the acoustic wave device by confining elastic waves within the excitation region, thereby maintaining optimal performance.
Implementation Method 1
a piezoelectric layer on the insulating layer and over the recess to define a cavity, a first excitation electrode on a first surface of the piezoelectric layer opposite to the cavity, a second excitation electrode within the cavity and on a second surface of the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes an insulating layer and a piezoelectric layer defining a cavity, a first excitation electrode on a first surface of the piezoelectric layer opposite to the cavity, a second excitation electrode on a second surface of piezoelectric layer and within the cavity, a wiring electrode on the piezoelectric layer and connected to the first excitation electrode, a lid, a conductive wall extending between a first portion of the wiring electrode and the lid, and a sealing frame extending between a second portion of the wiring electrode and the lid. A first width of a first portion of the sealing frame is larger than a second width of a second portion of the sealing frame. A third width of the second portion of the wiring electrode is smaller than the first width and is larger than the second width.