Elastic Wave Device Support Layer for Dicing Integrity
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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 confine energy and prevent separation, using a combination of low- and high-acoustic-impedance layers to effectively reflect elastic waves and enhance device strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dicing machine is used to cut elastic wave devices, then individual devices can be obtained, but the piezoelectric layer and low-acoustic-impedance layers separate from high-acoustic-impedance layers
Solution Approach 1:
The support layer is formed in advance to surround the acoustically reflective layer before the dicing process. This preliminary structural reinforcement prevents layer separation during subsequent cutting operations, allowing individual devices to be obtained without manufacturing defects.
Solution Approach 2:
The support layer acts as an intermediary element between the piezoelectric layer and the external cutting forces. It provides mechanical support and distributes stress during the dicing process, preventing direct separation between the acoustically reflective layer and the piezoelectric layer.
2Reliability
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 serves multiple functions simultaneously: it provides mechanical support to prevent layer separation during dicing, confines elastic wave energy to improve device performance, and offers structural protection. This multi-functionality justifies the additional structural element by delivering multiple benefits from a single component.
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 prevents separation of layers during cutting, maintains device integrity, and confines elastic wave energy on the piezoelectric layer side, enhancing the device's energy efficiency and strength.
Implementation Method 1
The acoustically reflective layer includes low-acoustic-impedance layers and high-acoustic-impedance layers that are stacked... 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
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.