Acoustic Wave Electrode Support Layout for Lower Loss
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Solution Overview
Problem
Acoustic wave devices using thickness-shear-mode bulk waves face challenges in reducing loss without compromising the structural integrity of the piezoelectric layer, as existing designs either suffer from increased fragility or inefficiency when attempting to minimize support for electrodes.
Innovation Solution
The design incorporates a piezoelectric substrate with a support structure that includes a lithium tantalate or lithium niobate layer and interdigitated electrode fingers, where the support overlaps specific regions to distribute strain and reduce loss, while through-holes in the piezoelectric layer minimize wave propagation through unsupported areas, maintaining device strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the supporter is removed to reduce loss, then loss is reduced, but the piezoelectric layer becomes fragile and may break
Solution Approach 1:
The supporter is divided into support portions and non-support portions. The support portions are positioned to overlap specific regions (central region and edge regions) of the piezoelectric layer, while non-support portions are positioned over gap regions. This segmentation allows the supporter to provide localized support where needed while leaving other regions unsupported to reduce loss.
Solution Approach 2:
Different regions of the piezoelectric layer are given different levels of support. The central region and edge regions (where electrode fingers are located) receive support to prevent breakage, while the gap regions between electrode fingers remain unsupported to reduce loss. This local differentiation of support quality resolves the contradiction between strength and loss reduction.
2Loss of energy
If the supporter is removed to reduce loss, then loss is reduced, but the device becomes fragile
Solution Approach 1:
The supporter is segmented into support portions and non-support portions that are strategically positioned. Support portions overlap the central region and edge regions of the piezoelectric layer to provide mechanical reinforcement, while non-support portions are positioned over gap regions to minimize interference with acoustic wave propagation, thereby reducing loss while maintaining device reliability.
Solution Approach 2:
The supporter provides localized support only where mechanical strength is needed (central and edge regions), while leaving gap regions unsupported. This local quality approach ensures device reliability is maintained in critical areas while allowing loss reduction in non-critical areas.
3Strength
If support is provided to maintain strength, then strength is maintained, but loss increases
Solution Approach 1:
The supporter is divided into support portions and non-support portions. By positioning support portions only over critical regions (central and edge regions) and leaving gap regions unsupported, the design provides minimum necessary support to maintain strength while minimizing the area that causes loss, thus resolving the contradiction between strength and loss.
Solution Approach 2:
The supporter provides differentiated support quality across different regions. Critical regions receive full support to maintain strength, while non-critical gap regions remain unsupported to minimize loss. This local quality approach optimizes the balance between strength and loss.
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 reduces loss and prevents device fragility by optimizing the distribution of strain and wave propagation, enhancing the acoustic wave device's performance and durability.
Implementation Method 1
A piezoelectric layer is provided on a supporter. A pair of electrodes are provided on the piezoelectric layer. The pair of electrodes face each other on the piezoelectric layer and are connected to potentials that differ from each other. A thickness-shear-mode bulk wave is excited by applying an alternate-current voltage between the electrodes.
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a support including a support substrate and a piezoelectric layer on the support and made of lithium tantalate or lithium niobate, and an IDT electrode on the piezoelectric layer and including busbars and electrode fingers. d/p is less than or equal to about 0.5. Some electrode fingers are connected to one busbar. Remaining electrode fingers are connected to another busbar. A crossing region includes a central region and edge regions in an electrode-finger-extending direction. A non-support portion of the support overlaps the central region and about 90% or more of a portion of the edge regions located between the electrode fingers. A through-hole is provided in about 50% or more of the piezoelectric layer overlapping gap regions and located between the electrode fingers. The support portion overlaps a portion of the gap regions where the electrode fingers are provided.