Acoustic Filter Electrode Structure for Corrosion and Power Durability
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Solution Overview
Problem
Designing acoustic filters that support high-power and high-frequency applications while maintaining corrosion resistance and durability is challenging, as copper-based electrode structures can corrode and aluminum-based structures are prone to acoustomigration, leading to shorter life cycles and increased size when additional cascaded resonators are used.
Innovation Solution
Implementing an electrode structure with a corrosion-resistant copper-based material that includes a combination of copper and silicon, which stabilizes the copper and inhibits corrosion without increasing sheet resistance, and optionally incorporating silver and tin for enhanced durability, allowing the acoustic filter to support high-power and high-frequency applications without the need for additional cascaded resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If copper-based electrode structure is used, then power durability is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent uses a composite electrode structure consisting of a copper layer combined with a silicon layer. The copper layer provides high power durability and conductivity, while the silicon layer provides corrosion resistance. This composite material approach resolves the contradiction by combining materials with complementary properties rather than using pure copper alone.
Solution Approach 2:
The silicon layer acts as an intermediary protective barrier between the copper electrode and the corrosive environment. This intermediate layer prevents direct contact between copper and corrosive substances, thereby protecting the copper from corrosion while maintaining the copper's electrical and mechanical properties.
2Reliability
If aluminum-based electrode structure is used, then corrosion resistance is improved, but acoustomigration resistance deteriorates
Solution Approach 1:
The patent combines copper and silicon in a layered structure where copper provides superior acoustomigration resistance compared to aluminum, while silicon provides corrosion protection. This composite structure achieves both properties simultaneously, resolving the contradiction between corrosion resistance and acoustomigration resistance.
3Power
If additional cascaded resonators are added, then power durability is improved, but device footprint increases
Solution Approach 1:
The patent changes the material parameters of the electrode structure by using copper-silicon composite materials with optimized thickness ratios. This material parameter optimization enables the filter to achieve high power durability with fewer resonators, thereby reducing the overall device footprint while maintaining or improving power handling capability.
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 enables acoustic filters to achieve a longer life cycle and maintain power durability without increasing the filter's footprint, supporting high-power and high-frequency applications while preventing corrosion, thus addressing the limitations of copper and aluminum-based electrode structures.
Implementation Method 1
A quantity of silicon within the electrode structure is sufficient to stabilize the copper and inhibit corrosion damage without significantly increasing sheet resistance
Implementation Method 2
The means for converting includes a metal layer with copper and silicon. The means for converting also includes an adhesion layer deposited between the metal layer and the means for producing the formed acoustic wave
Data Source
AI summary
An apparatus for filtering is disclosed that implements an electrode structure with corrosion resistance and power durability. In an example aspect, the apparatus includes an acoustic filter with a piezoelectric layer and the electrode structure. The electrode structure is formed by a metal layer comprising copper and silicon and by an adhesion layer. The adhesion layer is deposited between the metal layer and the piezoelectric layer.