Surface Acoustic Wave Package Structure for Stronger WLP Sealing
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Solution Overview
Problem
Surface acoustic wave devices with WLP structures face challenges in achieving both reduced size and increased joining strength, as existing designs either have insufficient joining strength or compromise the vibration space due to inadequate packaging.
Innovation Solution
A surface acoustic wave device design featuring a piezoelectric substrate with an IDT electrode, a support, a cover layer, and a connector that increases the joining area between the support and cover layer while maintaining a space above the electrode, using materials with specific Young's modulus relationships to prevent embedding and ensure separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cover layer is joined to the support only at the end surface, then the device structure is simple, but the joining strength is insufficient
Solution Approach 1:
The connector extends in the thickness direction (vertical dimension) to form a protruding structure that increases the joining area between the cover layer and support. This dimensional extension transforms a simple surface join into a multi-dimensional connection, significantly enhancing joining strength without complicating the overall package structure.
Solution Approach 2:
The connector acts as an intermediary component between the cover layer and support, providing a dedicated joining structure that mediates the connection. This intermediary element increases the joining area and strength while keeping the overall device structure relatively simple and modular.
2Strength
If the cover layer is heated to extend downward along the inner wall of the support, then the joining area increases, but the cover layer may contact the IDT electrode and obstruct vibration
Solution Approach 1:
The connector is designed with localized protrusion only in the thickness direction at specific positions, rather than uniformly extending the cover layer downward. This local quality approach increases joining strength at critical areas while maintaining the vibration space in other regions, preventing contact with the IDT electrode.
Solution Approach 2:
The connector is formed as a separate, discrete structure rather than a continuous extension of the cover layer. This segmentation allows the cover layer to maintain its primary function of covering the IDT electrode while the connector provides localized joining enhancement without obstructing vibration.
3Length of stationary object
If the support dimension in the normal direction is reduced, then the device thickness is reduced, but the joining strength between support and cover layer is reduced
Solution Approach 1:
The connector protrudes in the thickness direction to increase the joining area vertically, compensating for the reduced support dimension. This allows the support to be thinner while maintaining sufficient joining strength through the extended connector structure.
Solution Approach 2:
The connector's protrusion dimension in the thickness direction is optimized to provide adequate joining strength while keeping the overall device thickness reduced. By adjusting this parameter, the design achieves both thinness and strength.
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 design achieves a high-strength WLP structure with a maintained vibration space above the IDT electrode, enhancing the device's packaging efficiency and preventing contact between the cover layer and the substrate.
Implementation Method 1
an electrode that excites a surface acoustic wave is provided on one principal surface
Implementation Method 2
piezoelectric substrate on whose one principal surface an electrode that excites a surface acoustic wave is provided
Data Source
AI summary
A surface acoustic wave device includes a piezoelectric substrate with an IDT electrode that excites a surface acoustic wave provided on a principal surface, a cover layer opposing the principal surface and that covers the IDT electrode, a support provided in a standing manner around the IDT electrode on the one principal surface, and that, with the cover layer separated from the IDT electrode, supports a piezoelectric-substrate-side surface of the cover layer, and a connector that is provided on the piezoelectric-substrate-side surface of the cover layer and that joins the cover layer and the support to each other. At least a portion of a cover-layer-side end portion of the support exists in the connector. A dimension of the connector in a normal direction to the one principal surface is less than a dimension of the support in the normal direction.