Acoustic Wave Electrode Layout for Cavity Heat Dissipation

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Solution Overview

Problem

Acoustic wave devices face challenges in heat dissipation, particularly in devices with a recessed portion where heat produced during acoustic wave excitation does not dissipate efficiently due to the lack of a sufficient heat-dissipating path on the two main surfaces of the piezoelectric thin film.

Innovation Solution

The acoustic wave device incorporates a support with a cavity portion, a piezoelectric layer, and electrode fingers connected to busbars, featuring through holes of differing areas that face each other, creating an effective heat dissipation path by allowing heat to be discharged through the larger hole while minimizing the distance to the heat source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a recessed portion is provided in the support member, then the device structure is more compact, but heat dissipation from the cavity portion is insufficient

Engineering Contradiction:

Improvedevice compactnessVSAvoidheat dissipation

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The cavity portion is divided into multiple through holes of different sizes instead of a single cavity space. This segmentation allows different regions to serve different functions: the first through hole (larger area) serves as the primary heat dissipation path, while the second through hole (smaller area) provides secondary heat dissipation and structural support, resolving the contradiction between compactness and heat dissipation efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different through holes are designed with different areas to create localized functional zones. The first through hole with larger area is specifically optimized for heat dissipation, while the second through hole with smaller area provides supplementary heat dissipation and maintains structural integrity. This local differentiation allows the cavity to achieve both compactness and effective heat management

Inventive Principle:

Principle #3Local quality

2Temperature

If plate-shaped electrodes are provided on both main surfaces of the piezoelectric thin film, then heat dissipation path is improved, but device complexity increases

Engineering Contradiction:

Improveheat dissipation pathVSAvoidelectrode structure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The piezoelectric layer serves multiple functions simultaneously: it acts as the active piezoelectric element for acoustic wave generation and also provides a heat dissipation path between the two main surfaces. The electrode structure on both surfaces works dual-purpose for electrical function and thermal management, reducing overall device complexity while maintaining effective heat dissipation

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Temperature

If heat dissipation is increased from the cavity portion, then thermal management is improved, but the distance from heat source to discharge path must be minimized

Engineering Contradiction:

Improvethermal managementVSAvoiddistance from heat source to discharge path

Core Design Contradiction:

TemperatureVSLength of moving object

Solution Approach 1:

The through holes are positioned and sized in advance during design to optimize the heat dissipation path length. The first through hole is strategically placed and dimensioned to provide the shortest possible distance from the heat-generating IDT electrode region to the external environment, enabling efficient thermal management before heat accumulation becomes problematic

Inventive Principle:

Principle #10Preliminary action

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 configuration significantly enhances heat dissipation from the cavity portion, effectively managing internal pressure and facilitating the discharge of heat, thereby improving the device's thermal management.

Implementation Method 1

a piezoelectric layer (14) on the support substrate (16) a plurality of electrode fingers (28, 29) on the piezoelectric layer (14)

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

heat that is produced when an acoustic wave is excited propagates toward a recessed portion side of the support member

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

a first through hole (14c) and a second through hole (14d) that directly or indirectly reach the cavity portion (13c) are in the piezoelectric layer (14)

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS20230344409A1Acoustic wave device

Publication Date: 2023.10.26 MURATA MFG CO LTD

AI summary

An acoustic wave device includes a support including a support substrate, a piezoelectric layer, an IDT electrode including first and second electrode fingers on the piezoelectric layer, and two wiring electrodes each including two busbars connected to the first and second electrode fingers. A cavity open on a side of the piezoelectric layer is provided in the support. An intersection region is where adjacent first and second electrode fingers overlap each other when viewed in a direction orthogonal to an extending direction of the first and second electrode fingers. The cavity includes the intersection region in plan view. First and second through holes that directly or indirectly reach the cavity are provided in the piezoelectric layer. The first and second through holes face each other with the intersection region being interposed therebetween, and, in plan view, total areas of the first and second through holes differ.