Acoustic Wave Package Structure With Vacuum Cavities for Heat Isolation
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Solution Overview
Problem
Existing acoustic wave devices face issues with deterioration of characteristics and breakage of the piezoelectric layer due to external heat.
Innovation Solution
The acoustic wave device incorporates a support structure with a frame-shaped support frame surrounding the functional electrode, a lid covering the opening, and cavities under vacuum, which includes a through hole for communication between the cavities, to reduce heat impact and prevent breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the piezoelectric layer is exposed to external heat, then the device can operate normally, but the characteristics deteriorate and the piezoelectric layer breaks
Solution Approach 1:
A support frame is introduced as an intermediary structure between the piezoelectric layer and the external environment. The support frame includes a through-hole that allows the piezoelectric layer to be suspended, creating thermal isolation. This intermediary structure protects the piezoelectric layer from direct heat exposure while maintaining device functionality.
Solution Approach 2:
The support structure is segmented into multiple components: a support substrate, a support frame with through-holes, and a lid. This segmentation creates isolated cavities that thermally protect the piezoelectric layer. The through-holes in the support frame divide the space, allowing thermal management while maintaining structural integrity.
2Strength
If the piezoelectric layer is made thicker to prevent breakage, then strength increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The support frame provides beforehand cushioning and mechanical support to the piezoelectric layer. By suspending the piezoelectric layer through the through-holes in the support frame, the structure prevents breakage before it occurs, eliminating the need for excessive thickness while maintaining strength.
3Volume of moving object
If the piezoelectric layer is made thinner to reduce device size, then miniaturization is achieved, but the piezoelectric layer becomes more susceptible to breakage
Solution Approach 1:
The support frame acts as an intermediary that provides mechanical reinforcement to the thin piezoelectric layer. The through-holes in the support frame create a suspension structure that distributes stress, allowing the piezoelectric layer to be thin for miniaturization while preventing breakage through the supportive framework.
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 effectively reduces deterioration and breakage of the piezoelectric layer, maintaining device performance and integrity under heat exposure.
Implementation Method 1
the first cavity and the second cavity are under vacuum
Data Source
AI summary
An acoustic wave device includes a support including a support substrate, a piezoelectric layer on the support, a functional electrode at the piezoelectric layer, a frame-shaped support frame on the piezoelectric layer and surrounding the functional electrode in a plan view in a stacking direction of the support and the piezoelectric layer. A lid covering an opening of the support frame, wherein the support includes a first cavity at a position overlapping at least a portion of the functional electrode in the plan view, a second cavity defined by the piezoelectric layer, the support frame, and the lid between the piezoelectric layer and the lid. The piezoelectric layer includes a through hole communicating with the first and second cavities, and the first and second cavities are under vacuum.