Elastic Wave Package Structure for Moisture-Resistant Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Elastic wave devices with a multilayer film and piezoelectric thin film on a support substrate are prone to moisture penetration, which can affect their characteristics due to gaps between the insulating layer and support layer.
Innovation Solution
The design includes a support substrate with a piezoelectric thin film, interdigital transducer electrodes, wiring layers, an insulating layer, a spacer layer, and a cover, where the insulating layer surrounds the piezoelectric thin film and has a sloping region that increases the distance between its outer and inner edges, enhancing moisture resistance by preventing water penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat insulating layer is used to surround the piezoelectric thin film, then the device structure is simple and easy to manufacture, but moisture can penetrate through the interface between the insulating layer and spacer layer, reducing device reliability
Solution Approach 1:
The insulating layer is designed with a sloping region instead of a flat surface, creating an inclined interface with the spacer layer. This curvature changes the geometry from a horizontal interface to an angled one, preventing moisture from easily penetrating along the interface and improving the seal between layers.
Solution Approach 2:
The insulating layer has different structural characteristics in different regions: a flat region for general coverage and a sloping region specifically at the interface with the spacer layer. This local variation in structure provides enhanced moisture resistance where it is most needed while maintaining simplicity in other areas.
2Reliability
If the insulating layer is made thicker to prevent moisture penetration, then moisture resistance improves, but the device height increases and manufacturing complexity increases
Solution Approach 1:
By introducing a sloping region, the insulating layer creates an angled barrier that moisture must traverse. This geometric approach provides enhanced moisture resistance without requiring a proportional increase in the overall thickness of the insulating layer, thus controlling device height.
Solution Approach 2:
Instead of increasing moisture resistance solely by adding thickness in the vertical dimension, the invention introduces a sloping angle, utilizing the angular dimension to create a more effective moisture barrier. This allows for improved protection without a linear increase in device height.
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 improves the moisture resistance and reliability of the elastic wave device by creating an airtight environment, reducing the likelihood of water reaching the IDT electrodes and minimizing the height from the support substrate to the cover.
Implementation Method 1
a piezoelectric thin film (122)
Data Source
AI summary
An elastic wave device includes a piezoelectric thin film, IDT electrodes on the piezoelectric thin film, an insulating layer surrounding the piezoelectric thin film on a primary surface of a support substrate, a spacer layer surrounding the piezoelectric thin film in plan view, and a cover on the spacer layer. The spacer layer includes an outer edge and an inner edge closer than the outer edge to the piezoelectric thin film in plan view. The primary surface of the insulating layer closer to the spacer layer includes a sloping region that extends where the insulating layer overlaps the spacer layer in plan view and in which the distance from the first primary surface of the support substrate along the direction perpendicular or substantially perpendicular to the support substrate increases from the outer edge toward the inner edge.