UV Curable Inkjet Inks for Etch-Resistant Conductive Patterns
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Solution Overview
Problem
Existing etch-resistant inkjet inks for printed circuit boards face issues with high viscosity, solvent-related latency problems, and flake formation during the alkaline stripping process, which complicates the manufacturing of conductive patterns and increases costs and waste.
Innovation Solution
A UV curable inkjet ink composition that includes hydrolyzable polyfunctional monomers or oligomers and water absorption controlling monomers, which completely dissolves in the stripping solution, reducing flake formation and viscosity, and uses a colorant that decolorizes at high pH to facilitate visual inspection and efficient stripping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic acrylate compounds with high viscosity are used to ensure good adhesion and etch resistance, then etch resistance is improved, but ink viscosity becomes too high for reliable inkjet printing
Solution Approach 1:
The patent combines low-viscosity aromatic acrylate compounds (with pendant carboxyl groups) with acrylated epoxy monomers or dimers in a composite resin formulation. This composite approach allows the ink to achieve both low viscosity (50-500 mPa.s) for reliable inkjet printing and sufficient etch resistance through the synergistic interaction of the different resin components.
Solution Approach 2:
The patent changes the molecular structure parameters of the aromatic acrylate compounds by introducing pendant carboxyl groups and selecting specific molecular weights and structures that provide both low viscosity and good adhesion properties. This parameter optimization allows the ink to maintain low viscosity while achieving the required etch resistance.
2Ease of manufacture
If volatile organic solvents are used to reduce ink viscosity, then inkjet printing reliability is improved, but latency problems occur in inkjet print heads
Solution Approach 1:
The patent extracts and removes volatile organic solvents from the ink formulation, replacing them with non-volatile components. The ink achieves the required low viscosity (50-500 mPa.s) through the molecular structure design of the resin components themselves, particularly the low-viscosity aromatic acrylate compounds with pendant carboxyl groups, rather than relying on volatile solvents.
Solution Approach 2:
The patent changes the physical state parameters of the ink by eliminating volatile components and using non-volatile resin systems. The viscosity control is achieved through molecular structure design and component selection rather than solvent content, fundamentally changing how the ink achieves its flow properties.
3Manufacturing precision
If the photo resist layer is removed by developer, then the conductive pattern is revealed, but extra cost and chemical waste are generated
Solution Approach 1:
The patent extracts and eliminates the separate developer step from the manufacturing process. The etch-resistant inkjet ink serves dual functions as both the patterning layer and the etch resistance layer, allowing direct etching of the copper substrate through the ink pattern without requiring chemical development.
Solution Approach 2:
The patent merges the functions of the photo resist layer and the etch resistance layer into a single etch-resistant inkjet ink composition. This ink is printed directly onto the copper substrate, cured to form the pattern, and then serves as the etch mask, eliminating the need for separate photo resist application and development steps.
4Ease of operation
If flake size is controlled in alkaline stripping bath, then manufacturing process runs smoothly, but it requires filtering and monitoring of multiple parameters
Solution Approach 1:
The patent changes the chemical composition parameters of the etch-resistant ink by incorporating specific resin formulations with pendant carboxyl groups and acrylated epoxy components. These compositional changes result in ink that strips cleanly without forming problematic flakes, eliminating the need for filtering and complex monitoring of flake size parameters.
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 provides a low-viscosity inkjet ink that ensures reliable etch resistance and efficient stripping, eliminating flake-related manufacturing issues and reducing waste, while allowing for visual inspection of the conductive pattern quality.
Implementation Method 1
exposing the etch-resistant ink to actinic radiation to effect polymerisation
Implementation Method 2
removing the exposed metal or alloy by a chemical etching process wherein the etch-resistant ink is substantially solvent-free
Data Source
AI summary
A method of manufacturing conductive patterns including the steps of: a) UV curable inkjet printing a cured inkjet ink pattern on a metal sheet bonded to a non-conductive substrate; b) etching the metal sheet not covered by the cured ink pattern to expose the non-conductive substrate; and c) applying an alkaline solution to dissolve the cured inkjet ink pattern within 5 minutes.