Elastic Wave Device Shield Electrode Isolation

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Solution Overview

Problem

Existing elastic wave devices, such as duplexers, face insufficient isolation characteristics due to inadequate suppression of electromagnetic field coupling between transmission and reception filter sections, despite the presence of a shield electrode.

Innovation Solution

The elastic wave device incorporates a support frame with a dividing wall containing a shield electrode made of conductive material, extending through the entire length of the wall, and under-bump metal layers connected to the electrode structures, which are made of the same material, to effectively reduce electromagnetic field coupling between the filter sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a shield electrode is provided between the transmission filter and the reception filter, then electromagnetic field coupling is suppressed to some extent, but the isolation characteristics remain insufficient

Engineering Contradiction:

Improveisolation characteristicsVSAvoidelectromagnetic field coupling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The shield electrode is divided into multiple segments (first shield electrode, second shield electrode, third shield electrode) arranged at different positions and orientations. This segmentation allows each electrode segment to target specific coupling paths between transmission and reception filters, providing comprehensive suppression that a single shield electrode cannot achieve.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different shield electrode segments are positioned at specific locations where electromagnetic coupling occurs most strongly. The first shield electrode is placed near the transmission filter, the second shield electrode is positioned between the filters, and the third shield electrode is located near the reception filter. This local placement optimizes the shielding effect at critical coupling points.

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple shield electrodes are added to improve isolation characteristics, then electromagnetic field coupling is better suppressed, but device complexity increases

Engineering Contradiction:

Improveisolation characteristicsVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The support frame structure serves multiple functions: it provides mechanical support for the filters, creates the hollow cavities for acoustic wave propagation, and integrates the shield electrodes into its walls. This multi-functionality reduces the need for separate shielding components, thereby limiting the increase in device complexity despite adding multiple shield electrodes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The shield electrodes are merged with the support frame structure, where the frame walls containing the electrodes serve as both structural support and electromagnetic shielding. This integration combines mechanical support and electromagnetic shielding functions into a single unified structure, reducing overall device complexity.

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

This configuration significantly enhances common mode isolation characteristics by improving the electromagnetic shielding effect, resulting in better attenuation and isolation performance compared to conventional designs.

Implementation Method 1

A shield electrode made of a conductive material is provided in a groove provided in the dividing wall portion

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

an elastic wave element portion forming a transmission filter and an elastic wave element portion forming a reception filter are provided on the same piezoelectric substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9520859B2Elastic wave device including a conductive shield electrode and manufacturing method thereof

Publication Date: 2016.12.13 MURATA MFG CO LTD

AI summary

In an elastic wave device, a first electrode structure and a second electrode structure are provided on a piezoelectric substrate. The first electrode structure and the second electrode structure define first and second elastic wave element portions, respectively. A support frame on the piezoelectric substrate surrounds the first elastic wave element portion and the second elastic wave element portion. The support frame includes a dividing wall portion that divides the first elastic wave element portion and the second elastic wave element portion. A conductive shield electrode is provided in a groove provided in the dividing wall portion.