SAW Device Double-Layered Electrode Power Durability
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Solution Overview
Problem
Conventional surface acoustic wave (SAW) devices face challenges in enhancing power durability, lowering resistance, and reducing costs, particularly with the shift to higher frequency bands like 1.8 to 2 GHz, which degrades electrode performance and increases electrical resistance.
Innovation Solution
A surface acoustic wave device with a double-layered electrode structure featuring a Ti underlying film and an Al-Ti upper film, where Ti is added to the main electrode material, allowing for improved power durability and reduced resistance while maintaining cost-effectiveness through simplified production processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the frequency band is increased to 1.8 to 2 GHz, then the communication performance is improved, but the electrode finger width and gap are reduced to half or less, degrading the power durability
Solution Approach 1:
The patent changes the material composition parameters of the electrode by adding Ti (0.1-1.0 wt%) to Al, which fundamentally alters the material properties to achieve both high frequency performance and power durability. This compositional parameter change allows the electrode to maintain adequate finger dimensions at higher frequencies while resisting stress migration and electromigration.
Solution Approach 2:
The patent creates a composite electrode material by combining Al with Ti additives. This composite structure leverages the low resistivity of Al while incorporating Ti's superior strength and migration resistance, achieving a balance between electrical performance and mechanical durability at reduced finger dimensions.
2Speed
If the electrode finger width and thickness are reduced to half or less, then the frequency band is increased to 1.8 to 2 GHz, but the electric resistance increases four times or more
Solution Approach 1:
The patent modifies the material composition by adding Ti to Al, which changes the electrical properties of the electrode material. This compositional change compensates for the increased resistance caused by reduced cross-sectional area, maintaining lower overall resistance despite smaller finger dimensions required for higher frequency operation.
3Reliability
If a metal other than Al is added to Al to enhance the strength, then the power durability is improved, but the electrode material complexity increases
Solution Approach 1:
The patent employs controlled compositional parameter changes by adding small amounts (0.1-1.0 wt%) of Ti to Al. This limited compositional modification achieves the desired strength and migration resistance improvements without substantially complicating the material system or manufacturing process, maintaining relative simplicity while enhancing performance.
4Reliability
If the crystal grain size of Al is reduced to produce a large number of crystal grain boundaries, then the stress is released structurally, but the manufacturing complexity increases
Solution Approach 1:
The patent achieves stress release and improved power durability through material composition changes (adding Ti to Al) rather than through complex manufacturing processes aimed at controlling grain structure. This approach simplifies manufacturing by addressing the durability issue at the material formulation level rather than requiring complex thermal or mechanical processing to achieve desired grain structures.
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 double-layered structure significantly enhances power durability by up to five times and maintains low electrical resistance, achieving better performance than conventional methods while reducing production complexity and costs.
Implementation Method 1
If an excessive power is applied to an interdigital transducer (IDT) that excites or receives a surface acoustic wave, a stress migration and an electromigration will be caused in an electrode of the IDT. The electrode is damaged by the migrations depending on the electrode material.
Implementation Method 2
If an excessive power is applied to an interdigital transducer (IDT) that excites or receives a surface acoustic wave, a stress migration and an electromigration will be caused in an electrode of the IDT. The electrode is damaged by the migrations depending on the electrode material.
Implementation Method 3
A surface acoustic wave device as represented by a surface acoustic wave (hereinafter referred to as SAW) filter is widely employed for a mobile communication device
Data Source
AI summary
A surface acoustic wave device includes at least one interdigital transducer having electrodes of a double-layered structure in which an upper film and an underlying film are laminated. The upper film has a main component of Al and a first metal of Ti added to the main component. The underlying film has a main component of Ti.