Composite Acoustic Wave Filter Structure to Suppress Ripple Crosstalk
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Solution Overview
Problem
Acoustic wave devices with differentiated substrate thicknesses for each resonator complicate pickup and mounting, leading to potential deterioration of frequency characteristics due to ripple generation and propagation.
Innovation Solution
The acoustic wave device design includes a first and second piezoelectric layer with respective support substrates of different thicknesses, sealed by a sealing portion, and functional electrodes connected by conductive joining portions, which simplifies pickup and mounting while reducing ripple-induced frequency deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the support substrate is differentiated for each resonator to prevent ripple propagation, then frequency characteristics are improved, but pickup and mounting processes become complicated
Solution Approach 1:
The support substrate is divided into multiple regions with different thicknesses corresponding to different resonators. Each resonator region has a locally optimized substrate thickness to prevent ripple propagation while maintaining uniform thickness in other areas for simplified manufacturing and mounting.
Solution Approach 2:
The support substrate exhibits spatially varying thickness properties, where specific regions have differentiated thicknesses tailored to individual resonator requirements. This local differentiation prevents ripple propagation at resonator interfaces while maintaining overall structural integrity and simplifying the pickup process.
2Ease of manufacture
If the thickness of the support substrate is uniform to simplify pickup and mounting, then ease of manufacture is improved, but ripple propagation between resonators occurs causing frequency characteristic deterioration
Solution Approach 1:
The support substrate is segmented into regions of uniform thickness and regions of differentiated thickness. The uniform regions facilitate simplified pickup and mounting processes, while the differentiated regions at resonator locations prevent ripple propagation and maintain frequency characteristics.
Solution Approach 2:
The support substrate implements local quality variations where specific regions have optimized thicknesses for ripple prevention, while the majority of the substrate maintains uniform thickness for ease of manufacture. This localized differentiation resolves the contradiction between manufacturing simplicity and performance requirements.
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 simplifies the pickup and mounting process while effectively preventing frequency characteristic deterioration caused by ripples, allowing for uniform substrate thickness and improved acoustic wave device performance.
Implementation Method 1
a piezoelectric layer, and an IDT electrode. The piezoelectric layer is provided on the support substrate to overlap the space portion, and the IDT electrode is provided on the piezoelectric layer
Implementation Method 2
the leakage wave generated from one resonator may be reflected from a portion of the support substrate where the space portion is not provided and may propagate to another resonator
Data Source
AI summary
An acoustic wave device includes a first piezoelectric layer including a first main surface and a second main surface, a first support portion including a first support substrate that overlaps the first piezoelectric layer in a first direction, a first resonator provided on at least the first main surface of the first piezoelectric layer, a second piezoelectric layer including a third main surface and a fourth main surface, a second support portion including a second support substrate overlapping the second piezoelectric layer in the first direction, and a second resonator provided on at least the third main surface of the second piezoelectric layer. The first resonator and the second resonator each include a functional electrode. The support portion includes a space portion that overlaps at least a portion of the functional electrode of the resonator in a plan view in the first direction.