Multi-Layer Piezoelectric Electrode Adhesion

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Solution Overview

Problem

Piezoelectric elements in liquid ejecting heads face challenges with adhesion between the lower electrode film and the substrate, as well as between the lower electrode film and the piezoelectric layer, leading to inadequate displacement characteristics and reliability.

Innovation Solution

A piezoelectric element structure featuring a lower electrode film composed of layers with platinum, titanium, and iridium, specifically designed to enhance adhesion and toughness, including a first layer with platinum as the primary component, a second layer with titanium as the primary component, and a third layer with iridium as the primary component, with a thickness ratio of 6:7:3 to 2:1, and a manufacturing method involving sequential formation and calcination of these layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a simple lower electrode film structure is used, then the device complexity is reduced, but the adhesion between the lower electrode film and the substrate deteriorates

Engineering Contradiction:

Improvestructure of lower electrode filmVSAvoidadhesion between lower electrode film and substrate

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The lower electrode film is constructed as a composite structure with multiple layers containing different metal elements (platinum, titanium, iridium, rhodium, ruthenium, osmium) in specific combinations. This composite structure provides both strong adhesion to the substrate and good electrical conductivity, resolving the contradiction between simple structure and reliable adhesion.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a simple lower electrode film structure is used, then the manufacturing process is simplified, but the adhesion between the lower electrode film and the piezoelectric layer deteriorates

Engineering Contradiction:

Improvemanufacturing process of lower electrode filmVSAvoidadhesion between lower electrode film and piezoelectric layer

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The multi-layer composite structure of the lower electrode film is designed to provide optimal adhesion to the piezoelectric layer while maintaining ease of manufacture through established thin-film deposition techniques. The specific combination of metal elements creates a structure that bonds effectively to both the substrate and the piezoelectric layer.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If the lower electrode film lacks toughness, then the material selection is simplified, but the displacement characteristic deteriorates

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoiddisplacement characteristic

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The lower electrode film uses a composite structure with multiple metal elements that provide both toughness and flexibility. This composite approach enables the film to withstand mechanical stress and maintain good displacement characteristics while still allowing for variations in material composition to optimize performance.

Inventive Principle:

Principle #40Composite materials

4Adaptability or versatility

If the lower electrode film lacks toughness, then the material selection is simplified, but the long-term reliability deteriorates

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidlong-term reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The multi-element composite structure of the lower electrode film provides enhanced toughness and long-term reliability. The combination of platinum, titanium, iridium, and other metal elements creates a durable structure that maintains its mechanical and electrical properties over time, while still allowing flexibility in material selection and composition ratios.

Inventive Principle:

Principle #40Composite materials

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 enhanced adhesion and toughness of the lower electrode film improve the displacement characteristics and long-term reliability of the piezoelectric element, resulting in a more durable and reliable liquid ejecting head.

Implementation Method 1

the lower electrode film contains platinum, titanium, iridium, and oxygen and includes a first layer containing platinum as a primary component, a second layer containing titanium as a primary component, and a third layer containing iridium as a primary component

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a piezoelectric film made of a piezoelectric material having an electromechanical transduction function is interposed between two electrodes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7604331B2Piezoelectric element, method of manufacturing the piezoelectric element, and liquid ejecting head

Publication Date: 2009.10.20 SEIKO EPSON CORP

AI summary

A piezoelectric element includes a lower electrode film formed on one surface of a substrate, a piezoelectric layer made of a piezoelectric material and disposed on the lower electrode film, and an upper electrode film disposed on the piezoelectric layer, in which the lower electrode film contains platinum, titanium, iridium, and oxygen, and the lower electrode film includes a first layer disposed on the substrate and containing platinum as a primary component, a second layer disposed on the first layer and containing titanium as a primary component, and a third layer disposed on the second layer and containing iridium as a primary component.