Elastic Wave Reflective Layer Support to Prevent Dicing Separation
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Solution Overview
Problem
Elastic wave devices often experience separation of the piezoelectric layer and low-acoustic-impedance layers from high-acoustic-impedance layers during the cutting process with a dicing machine, leading to poor device characteristics.
Innovation Solution
The elastic wave device design includes a support layer that surrounds the acoustically reflective layer, with gaps provided outside the acoustic impedance layers to prevent separation, and uses a combination of low-acoustic-impedance and high-acoustic-impedance layers to effectively confine elastic wave energy on the piezoelectric layer side, while the support layer is made to surround the acoustically reflective layer in a plan view from the second main surface side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If individual elastic wave devices are cut with a dicing machine, then device production is achieved, but the piezoelectric layer and low-acoustic-impedance layers separate from each other
Solution Approach 1:
A support layer is introduced as an intermediary structure that surrounds the acoustically reflective layer in a plan view. This support layer acts as a mediator that mechanically reinforces the interface between the piezoelectric layer and low-acoustic-impedance layers during the dicing process, preventing separation while enabling device production
2Loss of energy
If low-acoustic-impedance layers and high-acoustic-impedance layers are stacked to reflect elastic waves, then energy confinement is improved, but layer separation occurs during cutting
Solution Approach 1:
The acoustically reflective layer is segmented into multiple acoustic impedance layers (low-acoustic-impedance layers and high-acoustic-impedance layers) stacked alternately. This segmentation creates multiple reflection interfaces for elastic wave energy confinement, while the support layer surrounding this segmented structure prevents layer separation during manufacturing
Solution Approach 2:
The support layer serves as a mediator that mechanically binds the segmented acoustic impedance layers together during the dicing process, maintaining layer integrity while allowing the acoustic reflection function to operate effectively
3Reliability
If the acoustically reflective layer is surrounded by a support layer, then layer separation is prevented, but device structure becomes more complex
Solution Approach 1:
The support layer performs multiple functions simultaneously: it surrounds and protects the acoustically reflective layer from separation during dicing, provides mechanical reinforcement to the overall device structure, and maintains the positional stability of the piezoelectric layer and acoustic impedance layers. This multi-functionality justifies the additional structural element
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 significantly reduces the likelihood of layer separation during cutting, enhances energy confinement, and increases the strength of the elastic wave device by ensuring the acoustically reflective layer remains intact, thereby maintaining device performance.
Implementation Method 1
elastic waves that propagate from the piezoelectric layer to the acoustically reflective layer are able to be reflected from an interface between the at least one low-acoustic-impedance layer and the at least one high-acoustic-impedance layer
Implementation Method 2
a piezoelectric layer including a first main surface and a second main surface facing the first main surface, an acoustically reflective layer stacked on the first main surface of the piezoelectric layer, an excitation electrode disposed on the piezoelectric layer
Data Source
AI summary
An elastic wave device includes a piezoelectric layer including a first main surface and a second main surface facing the first main surface, an acoustically reflective layer stacked on the first main surface of the piezoelectric layer, an excitation electrode disposed on the piezoelectric layer, and a support layer. The acoustically reflective layer overlaps at least the excitation electrode in a plan view of the piezoelectric layer from the side of the second main surface. The support layer surrounds the acoustically reflective layer in a plan view of the piezoelectric layer from the side of the second main surface.