Piezoelectric Actuator Wiring Insulation Thickness Optimization
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Solution Overview
Problem
The liquid discharge head with a piezoelectric film is prone to failure due to short-circuits and corrosion caused by creepage effects, especially when the insulation layer covering the wiring lines is not adequately thick to prevent these issues without causing substrate distortion or prolonging processing times.
Innovation Solution
A piezoelectric actuator design where the wiring lines are made thinner than the insulation layer, with the insulation layer having a thickness of 500 nm or less, ensuring sufficient coverage and preventing short-circuits while minimizing film stress and processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulation layer is increased to cover the wiring lines sufficiently, then the coverage property and electrical insulation are improved, but the substrate distortion and processing time increase
Solution Approach 1:
The patent changes the thickness parameter of the insulation layer to an optimal range (50-200 nm) that provides sufficient coverage and electrical insulation while avoiding excessive thickness that would cause substrate distortion and prolong processing time. This parameter optimization resolves the contradiction between insulation reliability and processing efficiency.
2Reliability
If the thickness of the insulation layer is increased to cover the wiring lines sufficiently, then the coverage property is improved, but the substrate distortion increases
Solution Approach 1:
The patent optimizes the insulation layer thickness parameter to 50-200 nm, which is sufficient to cover wiring lines and provide adequate coverage property while remaining thin enough to prevent substrate distortion during deposition and subsequent processing steps.
3Reliability
If the thickness of the insulation layer is increased to cover the wiring lines sufficiently, then the coverage property is improved, but the manufacturing complexity increases
Solution Approach 1:
By setting the insulation layer thickness within the optimal range of 50-200 nm, the patent simplifies the manufacturing process by avoiding the need for multiple deposition steps or complex patterning procedures that would be required for thicker or non-uniform insulation layers.
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 proposed solution effectively enhances the electric reliability of the piezoelectric actuator by preventing short-circuits and corrosion, while avoiding the drawbacks of increased film thickness, such as substrate distortion and prolonged processing times.
Implementation Method 1
A piezoelectric film, which changes its shape by an electric field being applied thereto, is applied to various industrial products as a means for moving or vibrating an object minutely and accurately.
Implementation Method 2
The liquid discharge head including the actuator having such a piezoelectric film may be prone to failure caused by a short-circuit between wiring lines or between a wiring line and a lower electrode due to a creepage effect on the device surface
Data Source
AI summary
An actuator includes a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode on a substrate in this order, a wiring line electrically connected to at least one of the first electrode and the second electrode, and an insulation layer arranged to contact and cover the wiring line, wherein a thickness of the wiring line is less than a thickness of the insulation layer in a direction perpendicular to the substrate, and the thickness of the insulation layer is 500 nm or less.