Acoustic Wave Electrode Package Structure for Moisture Resistance
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Solution Overview
Problem
The moisture resistance of the electrode unit in acoustic wave devices, particularly those using lithium niobate or lithium tantalate, is inadequate without a protective coat, leading to potential deterioration.
Innovation Solution
The acoustic wave device incorporates a frame-shaped support substrate with cavities, a resin sheet, a metallic frame, and an inorganic sheet to enhance moisture resistance, along with specific manufacturing steps involving substrates, covers, and cavity formation to protect the electrode unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no protective coat is provided on the electrode unit, then the device complexity is reduced, but the moisture resistance deteriorates
Solution Approach 1:
The patent implements a nested protective structure where the electrode unit is enclosed within a cavity formed in the support substrate, and this cavity is then sealed by a cover. This nested arrangement provides moisture protection without requiring a protective coat directly on the electrode surfaces, thus maintaining simplicity while improving reliability.
Solution Approach 2:
The protective structure is segmented into distinct functional components: the support substrate with its cavity, the cover that seals the cavity, and the electrode unit within. This segmentation allows each component to perform its specific function (support, protection, sealing) independently, providing effective moisture resistance while keeping the overall device design manageable.
2Reliability
If a protective structure with cavities and covers is added, then the moisture resistance is improved, but the device complexity increases
Solution Approach 1:
The support substrate serves multiple functions: it provides mechanical support for the electrode unit, creates the protective cavity through etching, and works with the cover to seal the electrode unit. This multi-functionality reduces the need for separate dedicated protective components, thereby improving moisture resistance while limiting the increase in device complexity.
Solution Approach 2:
The patent merges the protective function with the existing support substrate by forming the cavity directly within it through etching. This integration combines the structural support function with the protective enclosure function in a single component, reducing the total number of separate parts and simplifying the overall device architecture while still providing effective moisture protection.
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
The proposed structure and manufacturing method significantly improve the moisture resistance of the electrode unit, ensuring durability and performance of the acoustic wave device.
Implementation Method 1
a piezoelectric layer including a first principal surface and a second principal surface that face in opposite directions, at least one pair of electrodes located on the first principal surface to oppose each other in an intersecting direction that intersects a thickness direction of the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a piezoelectric layer, electrodes, a support substrate, a resin sheet, a metallic frame, and an inorganic sheet. The electrodes oppose each other in an intersecting direction that intersects a thickness direction of the piezoelectric layer. The support substrate includes a first cavity extending through the support substrate so as to overlap at least a portion of the electrodes as viewed in the thickness direction. The resin sheet is arranged on a surface of the support substrate opposite to the piezoelectric layer to close the first cavity. The metallic frame includes a second cavity therein and surrounds the piezoelectric layer and the electrodes. The inorganic sheet is arranged on a surface of the metallic frame opposite to the piezoelectric layer to close the second cavity.