Inkjet Pattern Formation With Random Multi-Pass Viscosity Control
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Solution Overview
Problem
Existing inkjet printing methods for pattern formation on electronic devices suffer from streaks and speckles, particularly in multi-pass systems, leading to insulation and conductivity irregularities, especially when using functional materials with varying wetting characteristics and uneven surfaces.
Innovation Solution
The method employs an ink with a viscosity ratio of 100 or more at landing to ejection, controlling ink droplet landing positions and amounts to avoid periodicity, using a random multi-pass approach with multiple movements and inkjet devices to form patterns with high precision and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-pass printing is used for high-resolution pattern printing, then manufacturing precision is improved, but streak-like irregularities occur due to long time between passes
Solution Approach 1:
The patent applies preliminary action by using a viscosifying agent that activates before the ink dries to increase viscosity and prevent ink flow during the multi-pass printing process. This preliminary viscosity increase ensures that ink deposited in earlier passes does not spread or create streaks when subsequent passes are made, maintaining both high resolution and uniformity.
Solution Approach 2:
The patent changes the viscosity parameter of the ink over time by incorporating a viscosifying agent that increases viscosity as the ink dries. This dynamic parameter change allows the ink to remain fluid enough for precise deposition during ejection, then becomes more viscous to prevent spreading between passes, resolving the contradiction between precision and uniformity.
2Adaptability or versatility
If inkjet printing is used to form patterns on boards with different wettability, then adaptability is improved, but ink flow occurs to the side of boards with higher wettability
Solution Approach 1:
The patent modifies the ink's viscosity parameter by adding a viscosifying agent, which increases the ink's resistance to flow. This parameter change allows the ink to be deposited accurately on boards with varying wettability characteristics without flowing sideways, maintaining pattern accuracy while preserving adaptability to different substrates.
Solution Approach 2:
The viscosifying agent acts as an intermediary substance that modifies the ink's flow characteristics. This intermediary component enables the ink to adhere properly to boards with different wettability levels by controlling its spread, thus maintaining both adaptability and manufacturing precision.
3Reliability
If phase change mechanism ink with high dot fixation property is used, then ink flow is suppressed, but streak-like irregularities occur in scan direction
Solution Approach 1:
The patent introduces a viscosifying agent that changes the viscosity parameter of the ink over time. This controlled viscosity increase suppresses unwanted ink flow while maintaining uniformity in the scan direction by ensuring consistent ink behavior during the multi-pass printing process, resolving the contradiction between dot fixation and scan uniformity.
4Manufacturing precision
If liquid amount is adjusted to reduce gloss streak, then appearance quality is improved, but coverage uniformity may be affected
Solution Approach 1:
The patent uses a viscosifying agent to control the viscosity parameter of the ink, which allows for better coverage uniformity even when liquid amount is adjusted. The increased viscosity prevents ink from pooling or spreading unevenly, ensuring that surface quality and coverage uniformity are both maintained despite variations in ink deposition quantity.
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 reduces streaks and speckles, ensuring uniform insulation and conductivity, with improved adhesion and precise pattern formation on diverse surfaces.
Implementation Method 1
using an ink having a ratio η2/η1 of a viscosity η2 at a temperature upon landing to a viscosity η1 at a temperature upon ejection equal to or more than 100
Implementation Method 2
the η2 being a viscosity at a temperature upon landing, the η1 being a viscosity at a temperature upon ejection
Data Source
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Figure 3
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AI summary
The present invention addresses the problem of providing a method of pattern formation by ink-jet printing, with which high-density printing with no streak or inconsistency is obtained, uniform insulating properties and conductive properties are obtained, and a print with high adhesion is obtained. The method of pattern formation of the present invention is a method of forming a pattern by ejecting ink droplets onto a substrate, which serves as a print medium from nozzles of an ink ejecting device, which has a plurality of nozzle holes arranged in a line, while moving multiple times perpendicularly to or in parallel with the column direction of the nozzles, the method being characterized in that a ratio η2/η1 of the ink is at least 100, where η1 is a viscosity at a temperature of ejected ink and η2 is a viscosity at a temperature of ink dropped onto the substrate, and, correspondingly to the gradation or density of pixels constituting the image data of the pattern, the volume of the ink used for forming a print of dots constituting the pattern formed on the substrate is controlled so as not to have certain periodicity with adjacent dots or uniformity over the print of the pattern.