Acoustic Wave Element Structure for Emission Attenuation and Strength
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Solution Overview
Problem
Existing acoustic wave devices face challenges in achieving high mechanical strength while effectively attenuating unwanted emissions, which are often compromised due to the limitations of air gaps and electrode configurations in current designs.
Innovation Solution
The acoustic wave device incorporates a piezoelectric layer on an element substrate with a functional electrode and wiring electrode, featuring an air gap overlapping the functional electrode, a mounting substrate with external terminals, metal bumps for coupling, and a sealing resin, along with an attenuator on the outer surface made of a different material or with a low acoustic impedance layer to attenuate unwanted emissions, enhancing mechanical strength and emission reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an air gap is provided in the element substrate, then unwanted emissions are attenuated, but mechanical strength is reduced
Solution Approach 1:
The patent applies composite materials by combining the element substrate with a reinforcing layer having different mechanical properties. This composite structure allows the air gap to remain for acoustic emission attenuation while the reinforcing layer compensates for the mechanical strength reduction caused by the air gap.
Solution Approach 2:
The element substrate is segmented into multiple functional layers including the base substrate, air gap region, and reinforcing layer. This segmentation allows each layer to perform its specific function - the air gap for acoustic attenuation and the reinforcing layer for mechanical strength - without compromising the other.
2Volume of moving object
If the element substrate is thinned to reduce size, then device compactness is improved, but mechanical strength and resistance to breakage are reduced
Solution Approach 1:
A composite structure is implemented where a thin element substrate is combined with a reinforcing layer. The reinforcing layer has higher mechanical strength and compensates for the reduced thickness, allowing the device to maintain compact size while achieving adequate mechanical strength and breakage resistance.
Solution Approach 2:
The reinforcing layer is applied locally to the element substrate, providing enhanced mechanical strength specifically where needed. This local reinforcement allows the bulk of the substrate to remain thin for compactness while critical areas gain the necessary strength.
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 results in acoustic wave devices with improved mechanical strength and effective attenuation of unwanted emissions, maintaining resonance characteristics and reducing spurious components, thereby enhancing the overall performance of the device.
Implementation Method 1
a piezoelectric layer on the element substrate
Implementation Method 2
an attenuator provided in at least a portion of an outer surface of the element substrate, except a surface of contact with the piezoelectric layer, and structured to attenuate unwanted emissions
Data Source
AI summary
An acoustic wave device includes an acoustic wave element including an element substrate, a piezoelectric layer on the element substrate, a functional electrode on the piezoelectric layer, and a wiring electrode on the piezoelectric layer and electrically coupled to the functional electrode, the element substrate including an air gap at a position overlapping a portion of the functional electrode in plan view in a stacking direction of the element substrate and the piezoelectric layer, a mounting substrate including an external terminal, a metal bump coupling the wiring electrode and the external terminal, sealing resin sealing the acoustic wave element and the metal bump, and an attenuator in at least a portion of the outer surface of the element substrate, except a surface of contact with the piezoelectric layer, and structured to attenuate unwanted emissions.