Silver Ink Composition for Low-Temperature Sintering
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Solution Overview
Problem
Conventional silver inks require high heating times and result in high electrical resistance values when forming metal films at low temperatures, making them unsuitable for modern organic electronics that demand further low-temperature sinterability.
Innovation Solution
A silver ink with specific configurations, including a dispersion medium with controlled vapor pressure, a protective agent with a mass average molecular weight of 115 or less, and a moisture content between 500 ppm and 50,000 ppm, which enables low-temperature calcination and formation of a metal film with a low resistance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional silver ink is used for low-temperature sintering, then substrate options are expanded to include resin and organic material substrates, but the heating time becomes excessively long (several tens of hours to several days) and the electrical resistance value becomes high
Solution Approach 1:
The patent changes multiple parameters simultaneously: uses a specific dispersion medium (carboxylic acid solvent with controlled boiling point), optimizes silver particle characteristics (surface area, surface state), and controls protective agent content. These parameter changes enable the silver ink to achieve low-temperature sintering (70°C or less) with dramatically reduced heating time (3 hours or less) and low electrical resistance (20 μΩcm or less), resolving the contradiction between low sintering temperature and excessive heating time
Solution Approach 2:
The patent creates a composite formulation combining specifically treated silver particles (with controlled surface area and surface state) dispersed in a carboxylic acid-based dispersion medium with controlled protective agent content. This composite material system enables simultaneous achievement of low sintering temperature, short heating time, and low electrical resistance, resolving the time-loss contradiction that plagues conventional silver inks
2Temperature
If conventional silver ink is used for low-temperature sintering, then substrate options are expanded to include resin and organic material substrates, but the electrical resistance value becomes high
Solution Approach 1:
The patent optimizes multiple parameters including dispersion medium type (carboxylic acid solvent), silver particle surface area, protective agent content, and sintering temperature. This comprehensive parameter optimization enables the formation of metal films with volume resistance of 20 μΩcm or less at sintering temperatures of 70°C or less, simultaneously achieving low-temperature processing and low electrical resistance for reliable organic electronic devices
Solution Approach 2:
The patent focuses on optimizing the local properties of the silver ink formulation, specifically the surface state and surface area of silver particles, and the chemical composition of the dispersion medium. By improving the local quality of the ink formulation (particle surface characteristics and solvent composition), the patent achieves both low sintering temperature and low electrical resistance, resolving the contradiction between temperature reduction and resistance increase
3Shape
If silver particles are protected with amine compound to achieve fine and uniform particle size, then low-temperature sintering becomes possible, but further reduction in sintering temperature to 70°C or less requires additional optimization of dispersion medium and protective agent
Solution Approach 1:
The patent changes the dispersion medium from conventional solvents to a carboxylic acid-based solvent with controlled boiling point, and optimizes the protective agent content to a specific range. These parameter changes maintain the particle size uniformity achieved through amine compound protection while enabling sintering at 70°C or less, further reducing the sintering temperature from the conventional 100-200°C range
Solution Approach 2:
The patent uses a carboxylic acid-based dispersion medium as an intermediary between the protected silver particles and the sintering process. This dispersion medium mediates the interaction between the amine-protected particles, enabling low-temperature sintering while maintaining particle size uniformity. The dispersion medium acts as a carrier that facilitates the sintering process at reduced temperatures without compromising particle characteristics
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 silver ink can form a practical metal film with a low resistance value at 70° C. or less, achieving low-temperature sinterability within 3 hours and a volume resistance of 20 μΩcm or less, suitable for organic electronics.
Implementation Method 1
the vapor pressure at 20° C. is 40 mmHg or less and the vapor pressure at 70° C. is 0.09 mmHg or more
Implementation Method 2
the protective agent are evaporated, and the sintering of silver particles proceeds
Implementation Method 3
the sintering of silver particles proceeds, whereby a metal film is calcined
Data Source
AI summary
A silver ink including silver particles and a protective agent containing at least one amine compound dispersed in a dispersion medium containing, as a main solvent, a solvent having a vapor pressure at 20° C. of 40 mmHg or less and a vapor pressure at 70° C. of 0.09 mmHg or more, in an amount of 80% or more on a mass basis relative to the total dispersion medium. The amine compound has a mass average molecular weight of 115 or less, and the total amount of the amine compound is 1 part by weight or more and 14 parts by weight or less per 100 parts by weight of the silver particles. The silver ink has a moisture content of 500 ppm or more and 50,000 ppm or less and enables a practical metal film to be formed even through calcination at a low temperature of 70° C. or less.