Liquid Discharge Head Electrode Segmentation for Adhesion
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Solution Overview
Problem
The existing liquid discharge heads face issues with poor adhesiveness between the diaphragm plate and the lower electrode, leading to peeling off during the patterning process, which results in decreased yield and reliability due to insufficient adhesiveness and potential short circuits.
Innovation Solution
The introduction of patterned openings in the lower electrode in the non-chamber region between adjacent liquid chambers, along with an adhesive film like titanium oxide, enhances adhesiveness and reduces stress, preventing peeling off and ensuring consistent film thickness and rigidity of the diaphragm plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous lower electrode is used in the non-chamber region, then electrical connectivity is maintained, but the diaphragm plate peels off due to poor adhesiveness and stress concentration
Solution Approach 1:
The lower electrode in the non-chamber region is divided into multiple separate electrodes positioned between adjacent liquid chambers, rather than using a continuous electrode. This segmentation reduces stress concentration and prevents peeling while maintaining electrical connectivity through the chamber regions.
Solution Approach 2:
The lower electrode structure is made non-uniform: continuous in chamber regions for electrical connectivity, and segmented in non-chamber regions for stress reduction. This local differentiation optimizes both adhesiveness and electrical functionality in different areas.
2Ease of manufacture
If the lower electrode is formed without openings, then manufacturing is simpler, but stress accumulates causing peeling and short circuits
Solution Approach 1:
The lower electrode is segmented with openings in the non-chamber region, which can be integrated into existing photolithography and etching processes. This segmentation prevents peeling and short circuits while maintaining compatibility with standard manufacturing workflows.
3Ease of manufacture
If the diaphragm plate thickness varies, then manufacturing is easier, but rigidity and performance become inconsistent
Solution Approach 1:
The lower electrode structure is differentiated between chamber regions (continuous) and non-chamber regions (segmented with openings). This local quality variation provides mechanical support that maintains consistent diaphragm plate thickness and rigidity across different areas, ensuring uniform performance.
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 solution effectively prevents the lower electrode from peeling off, improves manufacturing yield, and enhances the reliability of the liquid discharge head by maintaining consistent film thickness and rigidity, even after repeated use.
Implementation Method 1
the piezoelectric element to which a voltage is applied vibrates so as to deform (displace) a diaphragm plate forming a part of a wall of the liquid chamber. The liquid in the liquid chamber is pressurized by the deformation (displacement) of the diaphragm plate
Implementation Method 2
an adhesive film like titanium oxide, enhances adhesiveness and reduces stress, preventing peeling off
Data Source
AI summary
A liquid discharge head includes a nozzle plate, a liquid chamber substrate, a diaphragm plate, and a piezoelectric element. The nozzle plate has multiple nozzle holes from each of which a liquid is dischargeable in a discharge direction. The multiple nozzle holes are arrayed in an array direction. The liquid chamber substrate has a first face on the nozzle plate, multiple liquid chambers respectively communicating with the multiple nozzle holes, multiple chamber region in which the multiple liquid chambers are respectively disposed, and a non-chamber region outside the multiple chamber region. The diaphragm plate is disposed on a second face of the liquid chamber substrate. The piezoelectric element includes a first electrode over the diaphragm plate, a piezoelectric body on the first electrode, and a second electrode on the piezoelectric body. The first electrode has patterned openings disposed between adjacent liquid chambers in the array direction in the non-chamber region.