Inkjet Ink for Direct Polyimide Patterning
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Solution Overview
Problem
The existing methods for forming patterned polyimide films in electronics are inefficient due to the need for multiple materials and complex processes, and there is a challenge in optimizing viscosity, surface tension, and boiling point of solvents to achieve good jettability and storage stability in inkjet inks.
Innovation Solution
An inkjet ink composition containing an amide acid derivative or its imidized substance and a specific amide-based solvent, optimized for viscosity, surface tension, and boiling point, is developed to improve jettability and storage stability, allowing for direct pattern formation without the need for photoresists or etchants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods using photoresist and etching are used to form patterned cured films, then the films can be formed with desired patterns, but the process becomes complex and productivity decreases
Solution Approach 1:
The invention extracts and eliminates the photoresist and etching steps from the conventional multi-step process. By using inkjet printing to directly deposit the cured film pattern, the complex photoresist/etching sequence is replaced with a single direct patterning step, thereby improving productivity while maintaining pattern formation quality
Solution Approach 2:
The invention applies preliminary action by pre-formulating the cured film material with appropriate viscosity and surface tension characteristics that enable direct inkjet printing. The material is prepared in advance with optimized properties (viscosity 1-50 mPa·s, surface tension 20-70 mN/m) to allow direct patterning without requiring subsequent photoresist or etching steps
2Reliability
If the viscosity of inkjet ink is increased to improve film properties, then the ink jetting becomes difficult especially in piezoelectric systems with low jetting pressure
Solution Approach 1:
The invention applies parameter changes by optimizing the viscosity of the inkjet ink to a specific range (1-50 mPa·s) that balances jetting performance and film quality. This parameter optimization enables the ink to be jetted easily in piezoelectric systems while still forming high-quality cured films with desired properties
3Ease of operation
If the surface tension of inkjet ink is adjusted to improve jetting, then proper liquid droplet formation becomes difficult if surface tension is too low
Solution Approach 1:
The invention applies parameter changes by optimizing the surface tension of the inkjet ink to a specific range (20-70 mN/m) that balances jetting performance and droplet formation quality. This parameter optimization ensures proper meniscus formation during jetting while preventing excessive spreading of the deposited liquid droplets
4Productivity
If the boiling point of the solvent is lowered to improve drying speed, then the ink viscosity changes during jetting and jetting becomes difficult
Solution Approach 1:
The invention applies parameter changes by optimizing the boiling point of the solvent to a specific range (100-300°C) that balances drying speed and jetting performance. This parameter optimization prevents excessive evaporation during jetting that would change ink viscosity, while still enabling sufficiently fast drying to achieve the desired productivity improvement
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 inkjet ink enables the formation of patterned polyimide films with improved jettability and storage stability, reducing the number of manufacturing steps and materials required, while achieving desired electrical, mechanical, and thermal characteristics.
Implementation Method 1
an inkjet ink containing an amide acid derivative having a specific structure or an imidized substance thereof
Implementation Method 2
inkjet printing according to a piezoelectric system
Data Source
AI summary
The inkjet ink contains a component (A) including at least one kind of compound selected from compound (2) having a constitutional unit represented by formula (2a) described below and having at least one kind of molecular terminal group selected from the group of groups represented by formulas (2b) and (2c) described below, and compounds selected from the group of compounds represented by formula (3) to formula (6) described below or an imidized substance thereof, and an amide-based solvent (B) represented by formula (1) : wherein R1 is an organic group having 1 to 18 carbon atoms, R2 and R3 satisfy (i) or (ii) , R4 is hydrogen or methyl, n is an integer from 0 to 3, and m is 0 or 1: (i) R2 and R3 are each independently hydrogen or an organic group having 1 to 6 carbon atoms; (ii) R2 and R3 are mutually bonded to form a ring structure.