Elastic Wave Device Cover Segmentation for Compact Resonator Sealing
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Solution Overview
Problem
Elastic wave devices with longitudinally coupled resonator filters face challenges in size reduction and risk of contact between the cover member and IDT electrodes due to the placement of three-dimensional wiring portions and cover members, leading to increased dimensions and potential structural issues.
Innovation Solution
The elastic wave device design includes a cover member that surrounds the longitudinally coupled resonator elastic wave filter with a three-dimensional wiring portion positioned outside the filter, where the insulating layer extends beyond the cover member's opening edge, reducing the level difference and preventing contact between the cover member and IDT electrodes, and using the same insulating material for the cover member and insulating layer to minimize cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover member is provided to surround both the longitudinally coupled resonator elastic wave filter and the three-dimensional wiring portion, then the sealing is improved, but the dimensions of the elastic wave device become larger
Solution Approach 1:
The cover member is divided into a first cover member surrounding the longitudinally coupled resonator elastic wave filter and a second cover member surrounding the three-dimensional wiring portion. This segmentation allows each cover member to be optimized independently, enabling compact arrangement and reducing overall device dimensions while maintaining sealing performance for both components.
2Length of stationary object
If the cover member is positioned close to the IDT electrodes to reduce device size, then the dimensions are reduced, but the risk of contact between the cover member and IDT electrodes increases due to pressure from sealing resin
Solution Approach 1:
An insulating layer is introduced as an intermediary between the cover member and the IDT electrodes. This insulating layer prevents direct contact between the cover member and IDT electrodes, eliminating the risk of electrical contact or structural damage from sealing resin pressure, while still allowing the cover member to be positioned close to the IDT electrodes for compact device dimensions.
3Device complexity
If the three-dimensional wiring portion is integrated with the filter structure, then the device complexity is reduced, but the cover member cannot effectively seal both components without increasing dimensions
Solution Approach 1:
The cover member is segmented into first and second cover members that separately surround the longitudinally coupled resonator elastic wave filter and the three-dimensional wiring portion. This segmentation enables effective sealing of both components while maintaining compact device dimensions through optimized spatial arrangement.
Solution Approach 2:
The first and second cover members are arranged at different positions and orientations to separately enclose the filter and wiring portion. This dimensional arrangement allows both components to be sealed effectively without requiring a single large cover member, thus maintaining compact overall dimensions.
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 design effectively reduces the size of the elastic wave device and prevents contact between the cover member and IDT electrodes, while minimizing the risk of cracking due to thermal expansion differences.
Implementation Method 1
an element substrate that has piezoelectricity; an IDT electrode that is provided on the element substrate and that defines a longitudinally coupled resonator elastic wave filter
Data Source
AI summary
An elastic wave device includes an IDT electrode on a piezoelectric substrate to define a longitudinally coupled resonator elastic wave filter, a three-dimensional wiring portion on the piezoelectric substrate and connected to the longitudinally coupled resonator elastic wave filter, and a cover surrounding the longitudinally coupled resonator elastic wave filter on the piezoelectric substrate. The three-dimensional wiring portion includes a lower layer wiring line, an upper layer wiring line, and an insulating layer stacked between the lower layer wiring line and the upper layer wiring line. The cover includes a portion on the three-dimensional wiring portion.