Elastic Wave Device Multilayer Cover Pressure Resistance
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Solution Overview
Problem
Elastic wave devices, such as surface acoustic wave devices, face issues with pressure resistance during molding due to deformation of the cover member, which can lead to damage of the IDT electrode.
Innovation Solution
The use of a multilayer cover member structure with a first cover member having a higher glass transition point than the second cover member, where the first cover member is positioned away from the IDT electrode and the second cover member is in contact with the mold resin layer, dispersing pressure and preventing contact with the IDT electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer cover member is used, then the structure is simple, but the pressure resistance during molding is insufficient and the IDT electrode may be damaged
Solution Approach 1:
The cover member is divided into multiple layers (first cover member and second cover member) with different glass transition points. The first cover member has a higher glass transition point and provides structural stability, while the second cover member has a lower glass transition point and absorbs molding pressure, preventing damage to the IDT electrode.
Solution Approach 2:
The cover member uses a composite structure combining materials with different thermal properties. By laminating materials with different glass transition points, the composite structure achieves both simplicity in overall design and enhanced pressure resistance through differential material behavior during molding.
2Stability of the object's composition
If the cover member is made from material with high glass transition point, then the structural stability is good, but the material cannot absorb molding pressure effectively
Solution Approach 1:
Different regions of the cover member structure have different material properties tailored to their specific functions. The first cover member (closer to IDT) uses high glass transition point material for structural stability, while the second cover member (farther from IDT) uses low glass transition point material for pressure absorption, optimizing each layer's performance for its local requirement.
Solution Approach 2:
The glass transition point parameter is varied across different layers of the cover member. By selecting materials with different glass transition points, the structure achieves both structural stability (high Tg layer) and pressure absorption capability (low Tg layer), resolving the contradiction between these two requirements.
3Object-affected harmful factors
If the cover member is deformed by molding pressure, then the pressure can be absorbed, but the cover member contacts the IDT electrode causing damage
Solution Approach 1:
The cover member is segmented into layers with different pressure absorption characteristics. The second cover member (lower Tg) deforms preferentially under pressure to absorb molding forces, while the first cover member (higher Tg) maintains its shape and position, preventing contact with and damage to the IDT electrode.
Solution Approach 2:
The multi-layer structure is designed in advance so that the second cover member acts as a cushioning layer during molding. This pre-configured pressure absorption mechanism protects the IDT electrode from direct pressure contact, eliminating the harmful effect before it can occur.
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 enhances the pressure resistance of elastic wave devices by minimizing deformation of the first cover member and allowing the second cover member to absorb pressure, thereby protecting the IDT electrode from damage.
Implementation Method 1
The glass transition point of the first cover member is higher than that of the second cover member
Data Source
AI summary
An elastic wave device includes a piezoelectric substrate, an IDT electrode, and a cover member. The IDT electrode is provided on the piezoelectric substrate. The cover member is provided above the piezoelectric substrate and separate from the IDT electrode. The cover member includes a first cover member and a second cover member. The second cover member is laminated on a side of the first cover member opposite to the piezoelectric substrate. The glass transition point of the first cover member is higher than that of the second cover member.