Elastic Wave Device Shield Bump for Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing elastic wave devices, such as duplexers, fail to sufficiently suppress electromagnetic field coupling between transmission and reception filters, resulting in insufficient isolation characteristics.
Innovation Solution
Incorporating a conductive first bump as an electromagnetic shield between the transmission and reception filters on a piezoelectric substrate, with an optional second bump for electrical connection, made from the same material as the bumps, and configured to enhance the shield effect by varying height and diameter ratios and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield electrode is provided between the transmission filter and the reception filter, then electromagnetic field coupling is suppressed, but the isolation characteristics are still insufficient
Solution Approach 1:
The patent transitions from a planar shield electrode configuration to a three-dimensional bump structure. The bump extends vertically from the substrate surface, creating a dimensional advantage that provides more effective electromagnetic shielding by intercepting field lines in the vertical dimension, thereby achieving sufficient isolation characteristics that planar electrodes cannot provide.
Solution Approach 2:
The shield bump is constructed using composite material structure combining a conductive core (such as copper or aluminum) with a protective outer layer (such as solder or protective coating). This composite structure provides both effective electromagnetic shielding through the conductive material and environmental protection through the outer layer, achieving reliable isolation characteristics.
2Reliability
If a conductive bump is added as an electromagnetic shield, then isolation characteristics improve, but device complexity increases
Solution Approach 1:
The bump structure serves multiple functions simultaneously: it provides electromagnetic shielding to improve isolation characteristics, acts as an electrical connection element, and can serve as a mechanical support structure. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving improved isolation.
Solution Approach 2:
The patent merges the shield electrode function with existing bump structures used for electrical connections. By integrating the shielding function into the bump structure rather than adding a separate shield component, the design achieves improved isolation characteristics while minimizing increases in device complexity.
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 solution effectively prevents electromagnetic field coupling, significantly improving common-mode isolation characteristics compared to devices without the shield bumps.
Implementation Method 1
The first bump is provided on the piezoelectric substrate between the first elastic wave element portion and the second elastic wave element portion. The first bump is configured of a conductive material and defines and functions as an electromagnetic shield.
Data Source
AI summary
In an elastic wave device, a first electrode structure and a second electrode structure are provided on a piezoelectric substrate, first and second elastic wave element portions are configured by the first electrode structure and the second electrode structure, respectively, and a first bump that is configured of a conductive material to provide shielding is provided on an electrode formation surface of the piezoelectric substrate between the first elastic wave element portion and the second elastic wave element portion.