Silver Ink Composition for Low-Temperature Conductive Structures
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Solution Overview
Problem
Conductive inks used for forming high-conductivity coatings or patterns often require high temperatures, which are incompatible with flexible electronic and biomedical devices that require low processing temperatures, limiting their application on substrates like plastic and paper.
Innovation Solution
A silver-based ink composition comprising a silver salt, a complexing agent such as an alkylamine, and formic acid or its salt, which allows for the formation of conductive silver structures at temperatures of 120°C or less, enabling compatibility with a wide range of substrates and patterning techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperatures are used to form conductive coatings, then electrical conductivity approaches that of bulk silver, but the ink becomes incompatible with plastic and paper substrates that require low processing temperatures
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by using silver salts complexed with specific ligands (such as ammonia, amines, or carboxylic acids) that decompose at lower temperatures. This allows the reduction of silver salt to metallic silver at temperatures below 150°C, maintaining high electrical conductivity while being compatible with temperature-sensitive substrates like plastic and paper
Solution Approach 2:
The patent creates a composite ink formulation combining silver salts with organic complexing agents (ligands). This composite structure allows the silver to be delivered and reduced at low temperatures while the organic components facilitate controlled decomposition and reduction, achieving both low processing temperature and high electrical conductivity
2Reliability
If particle-based inks are used, then conductive metal particles can be incorporated, but the ink requires high temperatures to form conductive coatings
Solution Approach 1:
The patent changes from using pre-formed metal particles to using silver salt precursors that can be reduced in situ. This chemical parameter change allows the formation of conductive silver structures directly from the ink formulation at low temperatures, eliminating the need for high-temperature sintering or annealing processes required by particle-based inks
3Reliability
If precursor-based inks are used, then thermally unstable precursor complexes reduce to conductive metal, but decomposition occurs at temperatures near 150°C which is still too high for flexible substrates
Solution Approach 1:
The patent进一步优化 the precursor complex parameters by selecting ligands with specific decomposition characteristics and stability constants. The complexing agents are chosen to form stable complexes at room temperature but decompose at temperatures below 150°C (ideally below 100°C), enabling reduction to metallic silver at temperatures compatible with flexible and paper substrates while maintaining high electrical conductivity
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 ink achieves high electrical conductivity equivalent to bulk silver at mild temperatures, is stable at room temperature, and suitable for various printing methods, including direct ink writing, inkjet printing, and airbrush spraying, while maintaining compatibility with flexible substrates.
Implementation Method 1
a complex of a) a complexing agent and formic acid or b) a complexing agent and a salt of formic acid
Implementation Method 2
an acid for complexing with the complexing agent and for reducing the silver salt
Implementation Method 3
each of the complexing agent and the acid has a boiling point of about 120°C or less
Data Source
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AI summary
An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in the ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about 120°C or less.