Thin-Film Piezoelectric Element Active Length Extension

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Solution Overview

Problem

Conventional thin-film piezoelectric material elements have limited active length due to the placement of the opening and electrode area in the length direction, which restricts the displacement stroke and affects the expanding and shrinking motion, making it difficult to achieve a longer active length while maintaining electrical connectivity.

Innovation Solution

A thin-film piezoelectric material element with a laminated structure featuring a lower electrode film, a piezoelectric material film, and an upper electrode film, where a surface layer insulating film is disposed on the side surfaces and top surface, and a through hole is formed on the top surface with an upper electrode pad entirely inside the outer edge part, allowing for a larger space in the long-side direction without contacting the side surfaces, thereby extending the active length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the opening and electrode area are placed in the length direction of the piezoelectric material, then electrical connectivity is secured, but the active length is limited and displacement stroke is restricted

Engineering Contradiction:

Improveelectrical connectivityVSAvoidactive length

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The electrode pad is repositioned from the length direction to the width direction of the piezoelectric material element. The insulating layer is configured with an opening that exposes the electrode film on the side surface, allowing the electrode pad to make contact in the width direction rather than extending in the length direction. This dimensional repositioning frees up the length direction for maximum active length while maintaining electrical connectivity through the side surface contact.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The insulating layer acts as an intermediary structure that enables the electrode pad to contact the electrode film through its opening. The insulating layer with the opening serves as a mediator that allows electrical connection to be established through the side surface configuration, decoupling the electrical connectivity function from the length direction and enabling the electrode pad to be positioned in the width direction instead.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Length of moving object

If the active length is extended to increase displacement stroke, then position control precision is improved, but electrical connection and mechanical strength may be compromised

Engineering Contradiction:

Improveactive lengthVSAvoidelectrical connection

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The electrical connection is relocated from the length direction to the width direction through the side surface opening configuration. This allows the active length to be extended along the length direction without compromising electrical connection, as the electrode pad contacts the electrode film through the opening in the insulating layer on the side surface, perpendicular to the length direction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If the electrode pad contacts the side surfaces of the insulating layer, then electrical connection is secured, but the expanding and shrinking motion is restricted

Engineering Contradiction:

Improveelectrical connectionVSAvoidexpanding and shrinking motion

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The insulating layer is configured with different properties in different regions: the opening is positioned to expose the electrode film on the side surface for electrical connection, while the rest of the insulating layer maintains its insulating function. The electrode pad is positioned to contact only the exposed electrode film through the opening, not the side surfaces of the insulating layer itself, allowing motion while maintaining electrical connection.

Inventive Principle:

Principle #3Local quality

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 increases the active length and displacement stroke of the thin-film piezoelectric material element, enabling more precise position control of the head slider in hard disk drives by allowing a longer active length without compromising the electrical connection and mechanical strength.

Implementation Method 1

a thin-film piezoelectric material element which has a piezoelectric material and electrodes having thin-film like shape

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20170133045A1Thin-film piezoelectric material element, head gimbal assembly and hard disk drive

Publication Date: 2017.05.11 SAE MAGNETICS (HK) LTD

AI summary

A thin-film piezoelectric material element includes a laminated structure part having a lower electrode film, a piezoelectric material film laminated on the lower electrode film and an upper electrode film laminated on the piezoelectric material film. The thin-film piezoelectric material element includes a surface layer insulating film disposed on side surfaces of the laminated structure part and a top surface of the upper electrode film, and has a through hole formed on a top disposed part disposed on the top surface. The surface layer insulating film has a long-side disposed part disposed outside than the top disposed part, the long-side disposed part has a long-side width, along with the long-side direction, formed shorter than the through hole.