Multilayer Electrode for Piezoelectric Inkjet Heads

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Solution Overview

Problem

Piezoelectric elements used in ink-jet recording heads face issues with surface irregularities in gold-containing metal layers, leading to variability in performance and reduced durability due to electric field concentration, affecting the quality and yield of the piezoelectric layers.

Innovation Solution

A multilayer body with a low-resistance metal layer composed of a gold-containing sublayer and another metal, such as iridium, is used, with an adhesive sublayer in between, to minimize surface irregularities and enhance adhesion, resulting in a stable and high-quality piezoelectric element for ink-jet devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a gold-containing layer is used as the lower electrode layer material to achieve low electrical resistance and good thermal resistance, then the electrical and thermal performance is improved, but the surface irregularities increase and the adhesion to the piezoelectric layer deteriorates

Engineering Contradiction:

Improveelectrical resistance and thermal resistanceVSAvoidsurface irregularity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The lower electrode layer is divided into multiple sublayers: a first sublayer containing gold (for low electrical and thermal resistance), and a second sublayer (for smooth surface and good adhesion). This segmentation allows each sublayer to fulfill its specific function without compromising the others.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sublayers are assigned different material compositions and properties tailored to their specific functions: the first sublayer is optimized for electrical and thermal conductivity with gold content, while the second sublayer is optimized for surface smoothness and adhesion to the piezoelectric layer.

Inventive Principle:

Principle #3Local quality

2Reliability

If a gold-containing layer is used as the lower electrode layer material to achieve low electrical resistance, then the electrical performance is improved, but the crystalline phase formation of the piezoelectric layer is affected and the surface roughness increases

Engineering Contradiction:

Improveelectrical resistanceVSAvoidsurface roughness and crystalline phase quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The electrode layer is segmented into a first sublayer (gold-containing for electrical conductivity) and a second sublayer (for surface quality and piezoelectric layer formation). This prevents the gold layer from directly contacting the piezoelectric material, avoiding interference with crystalline phase formation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second sublayer acts as an intermediary between the gold-containing first sublayer and the piezoelectric layer, providing a suitable surface for perovskite crystal formation while the gold sublayer provides electrical conductivity underneath.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If a single-layer gold-containing structure is used to simplify the electrode construction, then the device complexity is reduced, but the surface irregularity increases and the adhesion deteriorates

Engineering Contradiction:

Improveelectrode layer structureVSAvoidsurface irregularity and adhesion

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The electrode layer is divided into multiple sublayers with distinct functions, which resolves the surface irregularity and adhesion problems while maintaining a relatively simple overall structure that can be integrated into the piezoelectric element.

Inventive Principle:

Principle #1Segmentation

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 provides a piezoelectric element with low surface roughness and improved thermal resistance, enabling reliable and stable ejection of small liquid droplets with reduced variability and increased durability.

Implementation Method 1

a piezoelectric film endowed with piezoelectric properties that expands and contracts with the rise and fall in the intensity of an applied electric field

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a low-resistance metal layer which is formed on the substrate and has a single-layer structure or a multilayer structure of two or more sublayers; wherein the low-resistance metal layer comprises a gold-containing layer or sublayer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS8449083B2Multilayer body, piezoelectric element, and liquid ejecting device

Publication Date: 2013.05.28 FUJIFILM CORP

AI summary

A multilayer body which includes a low-resistance metal layer having a low electrical resistance, excellent thermal resistance and low surface irregularity is provided. The multilayer body includes a substrate, and a low-resistance metal layer which is formed on the substrate and has a single-layer structure or a multilayer structure of two or more sublayers. The low-resistance metal layer includes a gold-containing layer or sublayer composed of gold and another metal.