Inkjet Post Electrode Formation for Reliable Wiring Lamination
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Solution Overview
Problem
The existing method for forming post electrodes in wiring laminated structures struggles to achieve a predetermined height, leading to interlayer connection failures and short defects, particularly in high-density pixel arrays like those found in image display devices, due to limitations in ink drying and ink distribution during the formation process.
Innovation Solution
A method using a liquid repellent conductive ink discharged via an inkjet head to form post electrodes with a predetermined height on lower electrodes, ensuring direct contact and reliable electrical connection by controlling droplet division and surface liquid repellency, thereby preventing interlayer connection failures and short defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the post electrode is formed by filling the through hole with conductive ink, then the through hole can be filled to form a post electrode, but the height of the post electrode is limited by the height of the insulating layer and cannot be increased beyond that limit
Solution Approach 1:
The conductive ink is applied to the lower electrode surface before the insulating layer is formed. This preliminary action allows the post electrode to be formed first, and then the insulating layer is coated around it, enabling the post electrode to protrude beyond the insulating layer height and achieve the required height for reliable upper electrode contact.
Solution Approach 2:
The conventional sequence is inverted: instead of forming the through hole in the insulating layer first and then filling it with conductive ink, the conductive ink is applied to form the post electrode first, and then the insulating layer is formed around it. This inversion resolves the height limitation problem.
2Manufacturing precision
If extra amount of conductive ink is provided to compensate for contraction during drying, then the post electrode height can be maintained, but the conductive ink may run off from the through hole and cause short defects
Solution Approach 1:
The conductive ink is applied to the lower electrode before the insulating layer is formed. This preliminary application allows precise control of ink placement and amount, preventing run-off while ensuring sufficient material for post electrode formation. The insulating layer is then formed to contain any potential run-off.
Solution Approach 2:
The insulating layer is formed after the conductive ink application to provide a containing structure that prevents ink run-off from causing short defects. This beforehand cushioning protects against the harmful effect of ink migration during drying.
3Reliability
If the post electrode height is increased to ensure reliable contact with the upper electrode, then interlayer connection reliability improves, but the risk of ink run-off and short defects increases
Solution Approach 1:
The post electrode is formed by applying conductive ink to the lower electrode before the insulating layer is formed. This allows the post electrode to be formed with sufficient height for reliable contact, while the subsequently formed insulating layer contains the ink and prevents run-off, thus achieving both reliability and defect prevention.
Solution Approach 2:
The insulating layer is formed after the conductive ink application to provide a protective containing structure. This beforehand cushioning prevents the harmful effect of ink run-off while allowing the post electrode to achieve the necessary height for reliable interlayer connection.
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 approach allows for the formation of post electrodes with a high aspect ratio, ensuring reliable electrical connections and reducing defective pixels in high-density displays by preventing interlayer connection failures and enhancing productivity.
Implementation Method 1
when a liquid repellent conductive ink which can impart surface liquid repellency to the post electrode is used as the conductive ink, the post electrode can be assuredly exposed from the insulating layer formed on the post electrode
Implementation Method 2
a droplet of a liquid repellent conductive ink is discharged from a nozzle of an inkjet head, allows the droplet to impact on the lower electrode provided on a base material
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(c)
AI summary
The problem of the present invention is to provide a method for forming a wiring laminated structure which enables forming a post electrode to protrude with a predetermined height on a lower electrode and to enable preventing interlayer connection failures or short defects, and the problem is solved by a method for forming a wiring laminated structure including impacting a droplet of a conductive ink discharged from a nozzle 11 of an inkjet head 10 onto a lower electrode 2 provided on a base material to form a post electrode with the use of the conductive ink, the conductive ink being a liquid repellent conductive ink which develops liquid repellency in the post electrode, and the post electrode being formed to protrude with a predetermined height on the lower electrode 2 by discharging the droplet under conditions that the droplet is not divided or the number of divided drop becomes one or less before the droplet impacts on the lower electrode 2.