Acoustic Wave Package Shielding for Input-Output Isolation

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Solution Overview

Problem

In acoustic wave devices with a wafer level package structure, using a metal support leads to capacitive coupling between input/output terminals, reducing isolation between input and output.

Innovation Solution

Incorporating a shield electrode between the metal support and input/output terminals to block capacitive coupling, maintaining isolation by using a metal support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal support is used in the acoustic wave device, then airtightness of the hollow space is improved, but capacitive coupling between input/output terminals increases, reducing isolation

Engineering Contradiction:

ImproveairtightnessVSAvoidcapacitive coupling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A shield electrode is introduced as an intermediary element between the metal support and the input/output terminals. This shield electrode blocks the capacitive coupling path while allowing the metal support to maintain airtightness. The shield electrode acts as a mediator that prevents the harmful electromagnetic field interaction between the conductive support and signal terminals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful capacitive coupling effect is extracted and isolated by separating the signal path from the metal support through the shield electrode. The shield electrode creates an electromagnetic shield that extracts the coupling interference from the system, allowing the metal support to remain for airtightness purposes.

Inventive Principle:

Principle #2Taking out (Extraction)

2Strength

If a metal support is used in the acoustic wave device, then structural strength is improved, but isolation between input and output deteriorates due to capacitive coupling

Engineering Contradiction:

Improvestructural strengthVSAvoidcapacitive coupling

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The shield electrode serves as an intermediary that allows the metal support to provide structural strength while preventing its conductive property from causing capacitive coupling. The shield electrode is positioned between the support and signal terminals, mediating the interaction and blocking the harmful electrical coupling while permitting mechanical support function.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If a metal support is used in the acoustic wave device, then manufacturing precision is improved through better airtightness, but device complexity increases due to additional shield electrode

Engineering Contradiction:

ImproveairtightnessVSAvoidstructure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The shield electrode is merged with existing structural elements of the device, such as being integrated into the support structure or positioned within existing cavities. This merging approach allows the shield function to be added without proportionally increasing overall device complexity, as the shield electrode utilizes existing spatial and structural resources.

Inventive Principle:

Principle #5Merging (Combining)

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 shield electrode effectively reduces or prevents the decrease in isolation between input and output terminals, enhancing the performance of acoustic wave devices with metal supports.

Implementation Method 1

a support made of metal is conductive and thus may generate capacitive coupling with input/output terminals disposed in the hollow space, and this capacitive coupling may reduce the isolation between an input and an output

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS20260019060A1Acoustic wave device, acoustic wave module, filter device, multiplexer, and communication apparatus

Publication Date: 2026.01.15 MURATA MFG CO LTD

AI summary

An acoustic wave device includes a piezoelectric substrate including a first main surface, first and second connection terminals, and a first grounding terminal on the first main surface, functional elements on the first main surface, a first shield electrode on the first main surface and connected to the first grounding terminal, a support on the first main surface around a region in which the first and second connection terminals, the first grounding terminal, the functional elements, and the first shield electrode are located, and a cover supported by the support and located opposite to the piezoelectric substrate. The support includes metal. The piezoelectric substrate, the support, and the cover define a hollow space, and the first shield electrode is located between the first connection terminal and a portion of the support located at a position closest to the first connection terminal, on the first main surface in plan view.