SAW Filter Shield Electrode Layout for Compact High-Frequency Modules
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Solution Overview
Problem
Existing high-frequency modules face challenges in reducing size while minimizing mutual interference between surface acoustic wave filters and internal wiring patterns, leading to increased area requirements on the multilayer substrate.
Innovation Solution
The implementation of a high-frequency module design where a shield electrode is positioned between the surface acoustic wave filter and internal wiring patterns, and a resin member is used to enhance coupling between the electrode and wiring patterns, reducing interference and allowing for a smaller module size without the need for additional shielding on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield electrode is disposed on the multilayer substrate to prevent mutual interference between the surface acoustic wave filter and internal wiring patterns, then mutual interference is reduced, but the area required for electrode patterns on the substrate increases
Solution Approach 1:
The shield electrode is moved from the horizontal plane (substrate surface) to the vertical dimension (cover layer), allowing interference prevention without increasing substrate area. The cover layer serves as a new spatial dimension to house the shield electrode, effectively separating it from the substrate's electrode patterns.
Solution Approach 2:
The shielding function is segmented from the substrate and assigned to the cover layer instead. This separates the concerns of substrate wiring from shielding requirements, allowing the substrate to be minimized while the cover layer handles the shielding function independently.
2Volume of moving object
If the module size is reduced, then integration is improved, but mutual interference between the surface acoustic wave filter and internal wiring patterns increases
Solution Approach 1:
By utilizing the vertical dimension through the cover layer, the shield electrode can be positioned close to the electrode pattern without increasing the module's footprint. This three-dimensional arrangement reduces interference while maintaining compact horizontal dimensions.
Solution Approach 2:
The cover layer acts as an intermediary structure that houses the shield electrode, mediating between the electrode pattern and the substrate wiring. This intermediary positioning allows the shield to effectively block interference paths without requiring additional horizontal space.
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 design effectively reduces the size of the high-frequency module while improving attenuation characteristics outside the pass band by minimizing mutual interference and optimizing the positional relationship between the electrode and wiring patterns, resulting in enhanced signal propagation and reduced degradation of attenuation characteristics.
Implementation Method 1
a piezoelectric substrate, an electrode pattern that is provided on the piezoelectric substrate
Implementation Method 2
a shield electrode that is grounded is provided in or on a surface of the cover that faces the module substrate or is provided in or on a surface of the cover that faces the piezoelectric substrate
Data Source
AI summary
A high-frequency module includes a module substrate including an internal wiring pattern, and a SAW filter including a piezoelectric substrate, an electrode pattern on the piezoelectric substrate, a support surrounding the electrode pattern, and a cover on the support covering the electrode pattern to define a hollow space together with the support and the piezoelectric substrate. The module substrate, the cover, and the piezoelectric substrate are disposed in this order in a perpendicular or substantially perpendicular direction with respect to the module substrate, and a shield electrode is provided on a surface of the cover that faces the module substrate or on a surface of the cover that faces the piezoelectric substrate.