Ultrasonic Probe Electrode Patterning Over-Etching

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Solution Overview

Problem

Conventional ultrasonic probes with piezoelectric elements experience increased electrical resistance and reduced sound pressure due to over-etching of the lower metal electrode layer, making it difficult to control in high-frequency regions.

Innovation Solution

The design includes a piezoelectric element with a support body, a first piezoelectric layer, a first conductive layer, a second conductive layer, and a second piezoelectric layer, where the second piezoelectric layer is positioned apart from the first piezoelectric layer to prevent over-etching of the lower electrode layer, maintaining low electrical resistance and allowing for efficient ultrasonic wave generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the piezoelectric material film and upper metal electrode layer are etched to form prescribed patterns, then the electrode patterns are formed, but the lower metal electrode layer is over-etched causing thickness reduction and resistance increase

Engineering Contradiction:

Improveelectrode pattern formationVSAvoidelectrical resistance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A protective film is introduced as an intermediary layer between the lower metal electrode layer and the etching environment. This protective film prevents direct exposure of the lower electrode to etching chemicals, thereby preventing over-etching while allowing precise formation of upper electrode patterns. The protective film acts as a mediator that protects the underlying electrode structure during the patterning process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film is formed on the lower metal electrode layer before the upper electrode patterning process. This preliminary protective measure ensures that the lower electrode is already protected against potential over-etching when the etching process begins for the upper electrode patterns. The protective film is applied in advance to prevent the harmful effect before it can occur.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the lower metal electrode layer thickness is reduced due to over-etching, then the electrode patterns can be formed, but the electrical resistance increases and power consumption increases

Engineering Contradiction:

Improveelectrode patterningVSAvoidelectric power consumption

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The protective film serves as a barrier that prevents etching chemicals from reaching and removing material from the lower metal electrode layer. This intermediary layer ensures that the lower electrode maintains its full thickness and low resistance characteristics throughout the manufacturing process, while still allowing the upper electrode to be precisely patterned.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the lower metal electrode layer is over-etched, then the upper electrode patterns can be formed, but the sound pressure of ultrasonic waves decreases

Engineering Contradiction:

Improveupper electrode pattern formationVSAvoidsound pressure reduction

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The protective film acts as a protective intermediary that prevents damage to the lower electrode layer during upper electrode patterning. By maintaining the integrity and thickness of the lower electrode, the protective film ensures that the ultrasonic element can generate adequate sound pressure waves without the degradation caused by over-etching.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables the production of ultrasonic probes with lower electrical resistance, allowing for larger sound pressure ultrasonic waves to be generated with lower electric power consumption, and results in a thinner piezoelectric element.

Implementation Method 1

a piezoelectric element comprising a piezoelectric material deposited on a thin film... when a voltage is applied to the piezoelectric material and causes it to vibrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9579082B2Ultrasonic probe and ultrasonic image diagnostic device

Publication Date: 2017.02.28 SEIKO EPSON CORP

AI summary

An ultrasonic transducer includes a support body, a first piezoelectric layer, a first conductive layer, a second conductive layer and a second piezoelectric layer. The support body has an opening section and a displacement section covering the opening section on one side of the support body. The first piezoelectric layer is disposed inside of the displacement section when viewed in a plan view along a thickness direction of the support body. The first conductive layer and the second conductive layer contact with the first piezoelectric layer. The second piezoelectric layer is disposed over the first conductive layer, apart from the first piezoelectric layer when viewed in the plan view. The second conductive layer is disposed over the second piezoelectric layer and intersects the first conductive layer when viewed in the plan view.