IDT Electrode Film Layout for High-Power Acoustic Wave Reliability

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Solution Overview

Problem

Conventional acoustic wave devices with epitaxially grown oriented films across the entire length of electrode fingers are prone to electrode destruction due to momentary high electric power application, particularly at the end portions.

Innovation Solution

The acoustic wave device incorporates a piezoelectric substrate with IDT electrodes featuring epitaxially grown oriented films only in the central region and unoriented films in the edge regions, along with a laminated metal film structure, to enhance electric power handling capability and prevent electrode destruction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If epitaxially grown oriented films are applied across the entire length of electrode fingers, then electric power handling capability is improved, but electrode destruction occurs at end portions under momentary high electric power

Engineering Contradiction:

Improveelectric power handling capabilityVSAvoidelectrode durability under momentary high power

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies different film types to different regions of the electrode fingers: epitaxially grown oriented films in the central region for high power handling, and non-oriented films in the end regions for durability under momentary high power. This local differentiation resolves the contradiction by optimizing each region for its specific functional requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrode finger structure is segmented into distinct regions (central region with oriented films and end regions with non-oriented films). This segmentation allows each segment to perform its specialized function, preventing the uniform structure from causing electrode destruction under momentary high power while maintaining overall power handling capability.

Inventive Principle:

Principle #1Segmentation

2Power

If oriented films are used in edge regions, then electric power handling is enhanced, but electrode destruction risk increases under momentary power application

Engineering Contradiction:

Improveelectric power handling capabilityVSAvoidelectrode destruction from momentary power

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent specifically addresses the edge regions by applying non-oriented films only in these areas, while maintaining oriented films in the central region. This local quality differentiation protects the edge regions from electrode destruction under momentary power application while preserving the power handling enhancement in the central region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the potential harm of using oriented films throughout (which causes electrode destruction at edges) into a benefit by strategically limiting oriented films to the central region where they provide power handling enhancement without causing destruction. The non-oriented films in edge regions prevent the harmful effect while the oriented films in central region provide the beneficial effect.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 improves the durability of the acoustic wave device against both continuous and momentary high electric power applications, reducing the likelihood of electrode destruction while maintaining improved electric power handling capabilities.

Implementation Method 1

The first electrode fingers and the second electrode fingers include epitaxially grown oriented films in the central region

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Implementation Method 2

an acoustic wave device includes a piezoelectric substrate, and an IDT electrode on the piezoelectric substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11824513B2Acoustic wave device

Publication Date: 2023.11.21 MURATA MFG CO LTD

AI summary

An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate. The IDT electrode includes first and second electrode fingers. When the propagation direction of acoustic waves is a first direction and the direction orthogonal or substantially orthogonal to the first direction is a second direction, an intersecting region of the IDT electrode includes a central region located toward the middle in the second direction and first and second edge regions on both sides in the second direction of the central region. The first and second electrode fingers include epitaxially grown oriented films in the central region and portions that do not include the oriented films in the first and second edge regions.