Acoustic Wave Wiring Layout With Overlapped Equipotential Electrodes
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Solution Overview
Problem
The challenge in acoustic wave devices is signal interference between overlapping wiring electrodes, which degrades electrical characteristics and can cause malfunctions in electronic devices due to differences in potential between the electrodes.
Innovation Solution
The acoustic wave device design includes a first and second element substrate with piezoelectric properties, where the wiring electrodes from each substrate overlap in a plan view, with one being a signal wiring electrode and the other a ground wiring electrode, both at the same potential, to minimize signal interference. The electrodes are connected through a bonding layer, ensuring free vibrations of IDT electrodes and protection from external environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wiring electrodes from first and second element substrates are arranged in overlapping relationship to reduce device size, then the area of the acoustic wave device is reduced, but signal interference occurs between the wiring electrodes
Solution Approach 1:
The patent applies equipotentiality by configuring overlapping wiring electrodes to have the same electrical potential. Specifically, signal wiring electrodes are paired with ground wiring electrodes at the same potential level, eliminating potential differences that cause interference. This allows the electrodes to overlap in plan view without generating harmful electromagnetic interference, thus reducing device area while maintaining signal integrity.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between overlapping wiring electrodes on different element substrates. This insulating layer prevents direct electrical coupling and signal interference between the electrodes while allowing them to be in close proximity or overlap in plan view, thereby reducing the overall device area without compromising electrical performance.
2Area of stationary object
If wiring electrodes are placed close together or overlap to minimize device footprint, then manufacturing precision requirements increase to prevent short circuits and ensure proper spacing
Solution Approach 1:
The insulating layer serves as a mediator that provides physical separation and electrical isolation between overlapping wiring electrodes. This intermediary structure relaxes manufacturing precision requirements because the insulating layer acts as a built-in spacer and protective barrier, preventing short circuits even when electrodes are placed in close proximity or overlap in plan view.
Solution Approach 2:
The patent resolves spacing issues by transitioning from two-dimensional planar spacing to three-dimensional layered arrangement. Wiring electrodes from different element substrates are stacked in the vertical dimension with insulating layers between them, allowing overlapping in plan view while maintaining adequate physical separation through the thickness direction, thus reducing footprint without increasing manufacturing difficulty.
3Volume of moving object
If element substrates are bonded with minimal distance to reduce device size, then the volume of the acoustic wave device is reduced, but signal interference and electrical characteristic degradation occur
Solution Approach 1:
The patent maintains reliable electrical characteristics by configuring wiring electrodes in equipotential relationships. Signal wiring electrodes are paired with ground wiring electrodes at the same potential, preventing interference even when element substrates are bonded with minimal distance. This equipotential configuration ensures stable electrical performance while enabling compact device volume.
Solution Approach 2:
Insulating layers are introduced as intermediaries between element substrates and between overlapping wiring electrodes. These intermediaries prevent direct electrical coupling and signal interference, allowing element substrates to be bonded with minimal distance while maintaining reliable electrical characteristics. The insulating layers act as protective barriers that enable compact integration without compromising device reliability.
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 effectively reduces signal interference, maintaining the electrical characteristics of the acoustic wave device and preventing malfunctions in electronic devices, ensuring reliable operation by maintaining the electrodes at the same potential and protecting them from external influences.
Implementation Method 1
a first element substrate (1) having piezoelectricity in at least a portion
Implementation Method 2
a bonding layer made of an insulator and provided between the first element substrate and the second element substrate
Data Source
AI summary
An acoustic wave device includes a first and second element substrates each having piezoelectricity, and bonding layers bonding the first and second element substrates to each other. First and second IDT electrodes and first and second wiring electrodes are respectively provided on the first and second element substrates. The first and second wiring electrodes are disposed one above the other with the bonding layer interposed therebetween to define a wiring electrode overlapped portion. In each of the wiring electrode overlapped portions, the first wiring electrode and the second wiring electrode are provided in one of combinations in which one wiring electrode is a signal wiring electrode and the other wiring electrode is a ground wiring electrode, both of the wiring electrodes are ground wiring electrodes, and both of the wiring electrodes are signal wiring electrodes at the same potential.