Acoustic Wave Package Shield Structure for Crack-Resistant Miniaturization
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Solution Overview
Problem
Acoustic wave filters face reliability issues due to stress-induced cracking of the piezoelectric layer during the packaging process, particularly during heat cycle testing, which complicates the miniaturization of these devices.
Innovation Solution
A packaged acoustic wave component design featuring a base layer with an acoustic wave filter on its upper side, a cap layer mounted on top with an electrical shield layer in between, and seal rings for enhanced mechanical and electrical protection, reducing external influences and stress on the piezoelectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the acoustic wave filter is decreased to achieve miniaturization, then the package size is reduced, but the piezoelectric layer becomes more susceptible to stress-induced cracking during packaging processes
Solution Approach 1:
The packaging structure is segmented into distinct functional layers: a base layer for mechanical support, an acoustic wave filter layer for signal processing, a cap layer for protection, and intermediate shielding layers. This segmentation allows each layer to be optimized independently - the base and cap layers provide mechanical strength to protect the piezoelectric layer, while the filter layer maintains its acoustic wave functionality despite the compact overall size.
Solution Approach 2:
Electrical shield layers are introduced as intermediary elements between the acoustic wave filter and the external environment. These shield layers act as mediators that protect the piezoelectric layer from electrical interference and mechanical stress during the packaging process, enabling miniaturization without compromising reliability.
2Reliability
If the acoustic wave filter is protected from external influences during packaging, then reliability is improved, but the package size increases
Solution Approach 1:
Multiple protective functions are merged into a single integrated packaging structure. The base layer and cap layer simultaneously provide mechanical protection, electrical shielding, and environmental isolation. The electrical shield layers are integrated between the filter and packaging layers, combining electrical protection with structural support. This merging allows comprehensive protection without proportionally increasing package size.
Solution Approach 2:
The packaging layers are designed to perform multiple functions simultaneously. The base layer provides both mechanical support and electrical reference; the cap layer provides both physical protection and electrical shielding; the intermediate layers provide both stress distribution and electrical isolation. This multi-functionality reduces the need for separate protective components, thereby limiting package size growth while improving reliability.
3Object-affected harmful factors
If electrical shielding is added to protect the acoustic wave filter, then electromagnetic interference is reduced, but the device complexity increases
Solution Approach 1:
The electrical shield layers are designed with uniform material properties and consistent spacing relative to the acoustic wave filter. This homogeneity simplifies the design and manufacturing process compared to non-uniform or position-dependent shielding arrangements. The repeated pattern of shield layers throughout the packaging structure creates a predictable electromagnetic environment without requiring complex variable geometry.
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 solution provides improved reliability, mechanical ruggedness, and reduced filter size by minimizing the impact of external factors and allowing for smaller filter stages, while maintaining high filter performance.
Implementation Method 1
an electrical shield layer disposed on the bottom side of the cap layer such that the electrical shield layer and the acoustic wave filter are positioned between the base layer and the cap layer
Implementation Method 2
The packaging process for multilayer piezoelectric substrate packages with acoustic wave devices can apply stresses to the piezoelectric layer
Data Source
AI summary
Aspects and embodiments disclosed herein include a packaged acoustic wave component comprising a base layer, an acoustic wave filter disposed on an upper side of the base layer, a cap layer mounted to the upper side of the base layer such that a bottom side of the cap layer faces the upper side of the base layer, and an electrical shield layer disposed on the bottom side of the cap layer such that the electrical shield layer and the acoustic wave filter are positioned between the base layer and the cap layer.