Acoustic Wave Electrode Layout for Thermal Warpage Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Piezoelectric layers with anisotropy in the coefficient of linear expansion, such as LiNbO3 or LiTaO3, are prone to warpage due to temperature changes, which can affect the performance of acoustic wave devices.
Innovation Solution
The acoustic wave device incorporates a support substrate with a piezoelectric layer having electrodes oriented parallel to the directions of differing linear expansion coefficients, and an energy confining portion between the substrate and the piezoelectric layer to suppress warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric layer with anisotropy in the coefficient of linear expansion is used, then the piezoelectric properties are improved, but warpage occurs due to temperature changes
Solution Approach 1:
The patent changes the physical parameters of the piezoelectric layer by controlling the orientation of its main axis relative to the substrate. By setting the angle between the main axis and the substrate surface to specific ranges (0°≤θ<30° or 60°<θ≤90°), the patent optimizes the balance between piezoelectric properties and thermal expansion characteristics, thereby suppressing warpage while maintaining functionality
Solution Approach 2:
The patent employs a composite structure consisting of the piezoelectric layer combined with the substrate, where the substrate provides mechanical support and thermal stability. This composite configuration helps counteract the anisotropic thermal expansion of the piezoelectric material, preventing warpage formation
2Reliability
If the piezoelectric layer is made from materials like LiNbO3 or LiTaO3, then the piezoelectric effect is enhanced, but the anisotropy in linear expansion coefficient causes manufacturing difficulties
Solution Approach 1:
The patent controls the manufacturing parameters by specifying precise angular ranges for the piezoelectric layer orientation (0°≤θ<30° or 60°<θ≤90°). This parameter control ensures that the layer is oriented in directions that minimize differential thermal expansion, thereby simplifying the manufacturing process and reducing the need for post-processing corrections
Solution Approach 2:
The patent performs preliminary action by pre-establishing the correct orientation of the piezoelectric layer during the manufacturing process. By setting the angle θ within the specified ranges before thermal cycling occurs, the patent prevents warpage from developing in the first place, avoiding the need for subsequent corrective manufacturing steps
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 suppresses warpage of the piezoelectric layer even when it exhibits anisotropy in the coefficient of linear expansion, ensuring stable performance of the acoustic wave device across temperature variations.
Implementation Method 1
a piezoelectric film is provided on a substrate
Implementation Method 2
a coefficient of linear expansion differs in a plane... when temperature changes, warpage may occur in the piezoelectric film due to a difference in the coefficient of linear expansion
Data Source
AI summary
An acoustic wave device includes a support substrate, and a piezoelectric layer provided on the support substrate. The piezoelectric layer has a first main surface opposite to a second main surface. The piezoelectric layer also includes a first direction orthogonal to a second direction. A first electrode is provided on the piezoelectric layer's first main surface, and a second electrode is provided on the piezoelectric layer's second main surface to face the first electrode. An energy confining portion is provided between the support substrate and the piezoelectric layer. The piezoelectric layer is anisotropic with respect to a coefficient of linear expansion, and in the piezoelectric layer, a coefficient of linear expansion in the first direction is different from a coefficient of linear expansion in the second direction. At least one of the piezoelectric layer, the first electrode, and the second electrode is parallel to the first direction.