Solvent-Resistant Thermal Inkjet Print Head Using Photo Resist Barrier
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Solution Overview
Problem
Thermal inkjet print heads are prone to dissolution, delamination, shrinkage, and distortion when exposed to strong organic solvents, which affects their functionality and printing performance over time.
Innovation Solution
The use of a thermal inkjet print head with a tape automated bonding (TAB) flex circuit and specific materials such as epoxy-based and methyl methacrylate-based photo resist materials, along with a TiN barrier layer and a polyimide nozzle plate, which provide resistance to organic solvents and maintain print head integrity for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used in the print head, then manufacturing is easier and cost is lower, but the print head degrades when exposed to organic solvents
Solution Approach 1:
The patent employs composite material structures throughout the print head assembly. The substrate combines silicon carbide with protective coatings, the TAB circuit uses polyimide with solvent-resistant adhesives, the barrier layer uses epoxy or acrylic polymers, and the nozzle plate uses polyimide with specialized bonding. These composite constructions provide chemical resistance to organic solvents while maintaining mechanical integrity and electrical functionality.
Solution Approach 2:
The patent introduces intermediary protective layers between the print head components and the organic solvent environment. The barrier layer serves as an intermediary protective coating on the substrate, the adhesive layers act as intermediaries bonding components while resisting solvent penetration, and the encapsulation materials provide an intermediary protective barrier. These intermediaries prevent direct contact between solvents and vulnerable components.
2Manufacturing precision
If the print head is designed for high performance with complex structures, then printing quality improves, but the device becomes more susceptible to dissolution and distortion
Solution Approach 1:
The patent utilizes flexible thin film structures that maintain structural integrity while providing protection. The TAB circuit employs a flexible polyimide substrate with thin film conductor layers, the barrier layer is a thin protective film on the substrate, and the nozzle plate uses thin polyimide material. These thin film structures resist solvent penetration while maintaining the precision features needed for high-quality printing.
Solution Approach 2:
The patent divides the print head into segmented, modular components each with specialized protective properties. The substrate is segmented with specific protective coatings, the TAB circuit is a separate modular assembly with its own solvent-resistant materials, the barrier layer is a distinct protective segment, and the nozzle plate is a separate component. This segmentation allows each part to be optimized for both precision and chemical resistance.
3Ease of manufacture
If the print head uses standard materials for ease of manufacture, then production cost decreases, but the print head experiences delamination and shrinkage
Solution Approach 1:
The patent modifies material parameters such as chemical composition, molecular structure, and physical properties to achieve solvent resistance. The substrate uses silicon carbide with specific protective coatings, the TAB circuit uses polyimide with adjusted adhesive properties, the barrier layer uses epoxy or acrylic polymers with specific cross-linking densities, and the nozzle plate uses polyimide with specialized bonding characteristics. These parameter changes provide dimensional stability while remaining manufacturable.
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 solution enables the print head to withstand exposure to organic solvents for months or years without significant degradation, ensuring continued functionality and printing performance, specifically with ketones, alcohols, esters, and other polar solvents.
Implementation Method 1
When power pulses are transmitted in accordance with print commands to the print head, the resistive heaters heat the ink in the ink chamber to create one or more pressure bubbles in the chamber that forces ink to eject in droplet form
Implementation Method 2
The use of a thermal inkjet print head with a tape automated bonding (TAB) flex circuit and specific materials such as epoxy-based and methyl methacrylate-based photo resist materials, along with a TiN barrier layer and a polyimide nozzle plate, which provide resistance to organic solvents
Data Source
Figure 1~9B
Figure 2~3
Figure 4~5
AI summary
An inkjet printing system includes a print head in fluid communication with an ink reservoir and having a plurality of orifices and a corresponding plurality of associated ejection chambers. The print head includes a substrate and a barrier layer disposed on the substrate. The barrier layer defines in part a plurality of fluid channels and the plurality of ejection chambers. The barrier layer includes a material selected from epoxy-based photo resist materials and methyl methacrylate-based photo resist materials. An orifice plate is disposed over the substrate. The orifice plate includes the plurality of orifices in fluid communication with the ejection chambers. The orifice plate comprises a material selected from polyimides and nickel.