Liquid Ejection Head Electrode Wiring Adhesion
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Solution Overview
Problem
The long-term use of existing liquid ejection heads with three-dimensional electrode pumps leads to degradation in adhesion between the substrate and electrode wiring lines, and between the electrode wiring lines and ridge portions, resulting in peeling and lifting issues that affect ink flow and ejection precision.
Innovation Solution
A liquid ejection head design featuring a pair of electrodes with a ridge portion and electrode wiring lines that cover the upper and side surfaces, extending from the substrate to both upstream and downstream sides, improving adhesion through a single-step processing method that enhances the coverage and sealing of the interface, preventing ink penetration and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode wiring lines are formed only on the upper surface of ridge portions in existing liquid ejection heads, then the manufacturing process is simple, but adhesion between the substrate and electrode wiring lines degrades over time causing peeling and lifting
Solution Approach 1:
The electrode wiring lines are extended from merely covering the upper surface of ridge portions to also covering the side surfaces and extending onto the substrate surface. This dimensional expansion from 1D (upper surface only) to 3D (multi-surface coverage) creates additional adhesion areas and prevents peeling by distributing stress across multiple surfaces.
Solution Approach 2:
The electrode wiring lines are designed to extend onto the substrate surface in advance, covering the interface between the ridge portions and substrate before ink flow occurs. This preliminary coverage prevents ink from penetrating into the interface and causing adhesion degradation, thereby preventing future peeling and lifting issues.
2Object-affected harmful factors
If electrode wiring lines cover only the upper surface of ridge portions, then the structure is simple, but ink can penetrate into the interface between ridge portions and substrate causing adhesion degradation
Solution Approach 1:
The electrode wiring lines function as a continuous thin film barrier that flexibly conforms to the three-dimensional structure, covering upper surfaces, side surfaces, and substrate interfaces. This continuous film structure prevents ink penetration into the interface between ridge portions and substrate, eliminating the harmful effect of ink-induced adhesion degradation.
3Duration of action of stationary object
If electrode wiring lines do not extend onto the substrate surface, then the manufacturing process is simpler, but peeling and lifting occur during long-term use affecting ejection precision
Solution Approach 1:
The electrode wiring line structure is segmented into multiple functional zones: coverage of upper surfaces, coverage of side surfaces, and extension onto the substrate surface. This segmentation allows each zone to perform its specific function (electrical conduction, structural support, adhesion prevention) while collectively extending the service life of the liquid ejection head.
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 improved adhesion and sealing structure effectively prevent peeling and lifting of electrode wiring lines and ridge portions, maintaining ink flow efficiency and preventing ejection failures even after long-term use.
Implementation Method 1
a method of using a micropump that generates an alternating current electroosmotic flow (hereinafter referred to as ACEO)
Data Source
AI summary
A liquid ejection head includes a pair of electrodes disposed on a first surface of a substrate forming part of a flow path for a liquid. The electrodes of the pair of electrodes are adjacent to each other in a transverse direction of the electrodes, and the liquid moves in the transverse direction upon application of a voltage across the electrodes. The electrodes each include a ridge portion disposed on the first surface and an electrode wiring line connected to a power source for applying the voltage. The electrode wiring line covers an upper surface of the ridge portion and side surfaces of the ridge portion and extends from parts covering the side surfaces of the ridge portion to a downstream side and an upstream side with respect to a direction in which the liquid moves, so as to cover the first surface.