Silver Nanoparticle Dispersion Low-Temperature Sintering
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Solution Overview
Problem
Existing methods for forming silver nanoparticles with excellent electrical conductivity and adhesivity to substrates at low temperatures face challenges such as residual impurities and poor adhesivity due to the use of dispersants and organic compounds, which require high-temperature treatments or result in suboptimal conductivity and durability.
Innovation Solution
Silver nanoparticles are produced through a reduction treatment using a silver-containing composition comprising silver acetonedicarboxylate, an amine compound with a primary amino group, and a polymer with urethane bonds, allowing for low-temperature sintering and improved dispersion stability, resulting in a silver element with high electrical conductivity and strong adhesion to substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silver metal particles are reduced to nanoscale size to achieve melting point depression and low-temperature sintering, then sintering temperature is reduced, but the particles become prone to contact and aggregate, requiring dispersants that leave residual impurities
Solution Approach 1:
The invention extracts and removes the dispersant from the final silver element product through a washing step. The silver nanoparticles are dispersed in a solvent during storage using a dispersant, but before forming the silver element, the dispersant is removed by washing the silver nanoparticles with a solvent, thereby achieving high purity silver element without residual dispersant impurities.
Solution Approach 2:
The invention uses a solvent as an intermediary medium. The solvent serves multiple functions: it disperses the silver nanoparticles during storage and transport, facilitates the removal of dispersant impurities through washing, and enables the ink to be applied to the substrate. This intermediary allows the system to achieve both low-temperature sintering and high purity.
2Stability of the object's composition
If a dispersant is added to the ink to prevent aggregation of fine silver metal particles, then dispersibility is improved, but residual impurities from the dispersant remain after sintering
Solution Approach 1:
The dispersant is extracted and removed from the silver nanoparticle structure through a washing step before element formation. The silver nanoparticles are washed with a solvent to remove the dispersant, and then dried to achieve high purity silver nanoparticles that can be sintered without residual impurities.
Solution Approach 2:
The dispersant removal action is performed preliminarily before the silver element formation process. By washing and drying the silver nanoparticles to remove the dispersant before applying the ink to the substrate and sintering, the invention ensures that no residual dispersant impurities remain in the final silver element.
3Temperature
If organic silver compounds are used to enable low-temperature decomposition, then sintering temperature is reduced, but nonvolatile carboxylic acid remains adhered to the nanoparticles requiring high-temperature treatment
Solution Approach 1:
The organic compound residues are extracted and removed from the silver nanoparticles through a washing step with a solvent. This removes the nonvolatile carboxylic acid and other organic residues that would otherwise require high-temperature treatment, enabling low-temperature sintering while achieving high purity silver element.
Solution Approach 2:
The invention changes the chemical composition parameters of the silver-containing composition to use silver acetonedicarboxylate combined with amine compounds and polymers with urethane bonds. This specific compositional change enables decomposition at low temperatures (150°C or lower) while the resulting products can be easily washed away, leaving pure silver nanoparticles.
4Temperature
If low-temperature sintering is performed to match the softening point of transparent resin substrates, then substrate damage is prevented, but adhesivity of the silver element to the substrate deteriorates
Solution Approach 1:
The invention changes the chemical composition of the silver-containing composition to include polymers with urethane bonds and amine compounds. These compositional changes enable the silver nanoparticles to decompose and form high-adhesivity silver elements at low temperatures (150°C or lower), matching the softening point of transparent resin substrates while achieving strong bond strength.
Solution Approach 2:
The silver-containing composition is a composite material system combining silver acetonedicarboxylate, amine compounds, and polymers with urethane bonds. This composite structure provides both low-temperature decomposability and high adhesivity to resin substrates, resolving the contradiction between low sintering temperature and strong bond strength.
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 enables the formation of silver films or lines with electrical conductivity comparable to bulk silver and excellent adhesivity at temperatures not exceeding 150°C, suitable for various applications including wiring and antibacterial materials, while avoiding residual impurities and high-temperature treatments.
Implementation Method 1
reduction treatment (treatment with a reducing agent or heat treatment) of a silver-containing composition
Implementation Method 2
polymer (C) obtained by polymerization of a monomer composition comprising diol (meth)acrylate compound (c1) having a urethane bond
Implementation Method 3
sintering at not higher than 150 °C
Implementation Method 4
heat treatment at not higher than 150 °C for a short time
Data Source
Figure 1~2
AI summary
Provided are silver nanoparticles having excellent dispersion stability in a solvent, and capable of forming on a substrate a silver element, such as a silver film or line, having excellent electrical conductivity and adhesivity through heating even at a lower temperature for a short time, as well as a method for producing the same, a dispersion liquid of the silver nanoparticles, and a substrate having a silver element formed thereon using the dispersion liquid. The silver nanoparticles contains, at a particular ratio, silver compound (A) represented by formula (1): amine compound (B) having a primary amino group; and polymer (C) obtained by polymerization of a monomer composition containing diol (meth)acrylate compound (c1) having a urethane bond represented by formula (2): (R1: hydrogen atom or methyl group; R2:-(CH2)n-; n: 1 to 4), and at least one monomer (c2) selected from (meth)acrylate monomers, acrylamide monomers, vinyl monomers, vinyl ether monomers, or monomers having an epoxy group.