Inkjet Metallic Pattern Formation via Plasma-Treated Substrate
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Solution Overview
Problem
Existing methods for forming metallic patterns, such as those used in circuits and electrodes, face challenges with adhesion to substrates, fine line reproducibility, and conductivity, particularly due to limitations in temperature conditions and the stability of metal nano-particles and ion solutions.
Innovation Solution
A method involving an inkjet process with ink containing a nonelectric plating catalyst precursor, where the substrate undergoes plasma treatment and the ink has a pH of 9.0 to 14.0, enhancing adhesion and reproducibility by forming functional groups and improving surface energy, allowing for effective nonelectric plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metallic nano-particles are used and sintered at 200-300°C, then processing steps are decreased and utilization efficiency of starting materials is improved, but complete fusing of metallic particles together is difficult and severe limitations of temperature and conditions remain to reduce electric resistance
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by incorporating specific complexing agents (EDTA, DTPA, or their salts) with metal salts at controlled ratios. This chemical parameter modification enables the metal particles to fuse completely at the low sintering temperature of 200-300°C, achieving both low electric resistance (≤10 μΩ·cm) and complete particle fusion without requiring higher temperatures
2Ease of manufacture
If metal salt with insufficient complexing agent ability is used, then a conductive pattern can be formed from solution, but reducing reaction of metal salt easily proceeds resulting in poor storage stability of solution
Solution Approach 1:
The patent introduces strong complexing agents (EDTA, DTPA, or their salts) as intermediary substances that coordinate with metal ions to form stable complexes. These complexing agents act as mediators between the metal salt and the reducing environment, preventing spontaneous reducing reactions during storage while still allowing controlled reduction during the sintering process to form conductive patterns
3Reliability
If inkjet method with catalyst is used to form circuit pattern followed by nonelectric plating, then adhesion and conductivity are improved, but additional layer should be provided on support reducing production efficiency
Solution Approach 1:
The patent merges multiple functions into a single ink formulation: the ink simultaneously serves as the pattern deposition medium, the catalyst source for nonelectric plating, and the adhesion promoter. By incorporating nonelectric plating catalysts (Pd, Pt, Rh, Ir, or their compounds) along with complexing agents and surfactants in the ink, the process eliminates the need for separate additional layers while maintaining excellent adhesion and productivity
4Manufacturing precision
If conventional resist method is used to form metallic pattern, then precise pattern formation is achieved, but process is manifold and consumes plenty of time with many useless points
Solution Approach 1:
The patent extracts and eliminates the unnecessary intermediate steps from the conventional resist method. Instead of coating resist, performing development, etching, and peeling, the invention directly deposits metal-containing ink that self-organizes into precise patterns through the nonelectric plating reaction, keeping only the essential pattern formation step and eliminating all wasteful intermediate processes
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 method achieves excellent adhesion and fine line reproducibility with improved conductivity, reducing the complexity and energy consumption of the process while maintaining stability and efficiency.
Implementation Method 1
the surface of said substrate is constituted of ink non-absorptive resin and has been subjected to a plasma treatment
Implementation Method 2
a printing process to print a pattern portion on a substrate by means of an inkjet method utilizing ink containing a precursor of a nonelectric plating catalyst
Implementation Method 3
a plating process to form a metallic pattern by nonelectric plating on said pattern portion
Implementation Method 4
ability of a complexing agent, which coordinates to metal salt and stabilizes said metal salt
Data Source
AI summary
A method for forming a metallic pattern, which is provided with a printing process to print a pattern portion on a substrate by means of an inkjet method utilizing ink containing a precursor of a nonelectric plating catalyst and a plating process to form a metallic pattern by nonelectric plating on said pattern portion, wherein the surface of said substrate is constituted of ink non-absorptive resin and has been subjected to a plasma treatment, and said ink has a pH value at 25° C. of not less than 9.0.