Elastic Wave Wiring Layout for Thermal Cycle Disconnection Resistance
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Solution Overview
Problem
Existing elastic wave devices face challenges in reducing wiring electrode disconnection, especially under severe temperature cycles, which affects their reliability and performance.
Innovation Solution
The elastic wave device incorporates a support layer with a cavity and a first insulating layer extending through the side surface of the multilayer film, along with a second insulating layer between the wiring electrode and the support substrate, to enhance mechanical stability and reduce stress on the wiring electrode, thereby preventing disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the multilayer film is not provided in the region outside the IDT electrode region, then the wiring electrode can be extended to the insulating layer for electrical connection, but the wiring electrode becomes vulnerable to disconnection under temperature cycles
Solution Approach 1:
The patent applies beforehand cushioning by providing a support layer that extends into the region where the multilayer film is not disposed, specifically beneath the wiring electrode. This support layer acts as a preventive measure against thermal stress and mechanical deformation that would otherwise cause wiring electrode disconnection during temperature cycles, thereby cushioning the wiring electrode from harmful effects before they occur.
Solution Approach 2:
The support layer serves as an intermediary element between the wiring electrode and the support substrate. It provides mechanical support and stress distribution to the wiring electrode in the region where the multilayer film is absent, mediating the mechanical and thermal stresses that arise during temperature cycles and preventing direct stress concentration on the wiring electrode.
2Reliability
If the support layer extends to a region above the inner end of the first insulating layer, then the wiring electrode is better protected from disconnection, but the device structure becomes more complex
Solution Approach 1:
The support layer is configured with local quality by extending specifically to a region above the inner end of the first insulating layer, rather than uniformly across the entire device. This localized extension provides targeted support precisely where the wiring electrode is most vulnerable to disconnection, while avoiding unnecessary complexity in regions where support is not needed.
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 significantly reduces the occurrence of wiring electrode disconnection and improves the device's reliability, even under repeated temperature cycles from low to high temperatures, enhancing its thermal shock resistance and overall performance.
Implementation Method 1
a piezoelectric thin film is provided on a support substrate
Data Source
AI summary
An elastic wave device includes a multilayer film including a piezoelectric thin film laminated on a support substrate. In a region outside a region in which an IDT electrode is provided, the multilayer film is not disposed. A first insulating layer extends from at least a portion of the region to a region on the piezoelectric thin film. A wiring electrode extends to a region on the first insulating layer from a region on the piezoelectric thin film and to extend to a region on a portion of the first insulating layer located in the region. A support layer including a cavity defining a hollow space is provided on the support substrate. The support layer includes, on the wiring electrode, a portion extending from the region to a region above an inner end of the first insulating layer.