Coated Silver Nanoparticles Low-Temperature Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming silver nanoparticles struggle with achieving low-temperature sintering on flexible substrates with low heat resistance, as the surface tension of silver nanoparticles leads to aggregation and high sintering temperatures, limiting their use in compact electronic devices.
Innovation Solution
The use of medium- to short-chain alkylamines and alkyldiamines with boiling points between 100°C to 250°C to form a complex compound with silver oxalate, allowing for low-temperature thermal decomposition and sintering of coated silver nanoparticles at 120°C or lower, without the need for a solvent or reducing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silver nanoparticles are manufactured with small mean particle diameter to increase specific surface area, then low-temperature sintering capability is improved, but the particles aggregate during manufacturing due to surface tension, resulting in coarse particles
Solution Approach 1:
The patent introduces a protective molecule as an intermediary substance that adsorbs onto the surface of silver nanoparticles during synthesis. This protective layer mediates the interaction between nanoparticles, preventing direct contact and aggregation caused by surface tension. The protective molecule allows small particles to be manufactured uniformly without clumping, enabling subsequent low-temperature sintering while maintaining particle size control.
Solution Approach 2:
The patent applies preliminary protective action by coating silver nanoparticles with protective molecules during the synthesis stage, before the sintering process. This preliminary protection prevents the harmful aggregation effect from occurring during manufacturing and storage. The protective layer is subsequently removed or decomposed during controlled sintering, allowing particles to bond at low temperatures without premature aggregation.
2Ease of manufacture
If conventional silver nanoparticles are used, then manufacturing process is simple, but sintering temperature must be 200°C or higher, limiting use on low-heat-resistant substrates
Solution Approach 1:
The patent changes the surface parameter of silver nanoparticles by introducing protective molecules with specific chemical properties. This parameter change (surface coating) fundamentally alters the sintering behavior, enabling sintering at temperatures of 150°C or lower, which is sufficiently low for processing on polyethylene terephthalate and other low-heat-resistant substrates while maintaining manufacturing simplicity.
3Quantity of substance
If large amounts of reaction solvents, protective molecules and reducing agents are used to synthesize metal fine particles, then nanoparticle formation is achieved, but waste products are generated, requiring improvement from resource conservation and ecological viewpoints
Solution Approach 1:
The patent employs a self-service approach where the protective molecule serves dual functions: it protects the nanoparticles during synthesis and can be decomposed to provide reducing conditions for nanoparticle formation. This eliminates the need for separate reducing agents. The process is designed so that the protective molecule's decomposition products serve the reduction function, reducing waste while maintaining high nanoparticle yield.
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
This method enables the production of coated silver nanoparticles with high yield and superior dispersibility, allowing for the formation of electrically conductive films on low-heat-resistant substrates like PET or polypropylene at room temperature or lower, reducing energy and resource consumption.
Implementation Method 1
low-temperature thermal decomposition and sintering of coated silver nanoparticles at 120°C or lower
Implementation Method 2
form a complex compound with silver oxalate
Implementation Method 3
sintering of coated silver nanoparticles at 120°C or lower
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(b)
AI summary
The present invention provides coated silver nanoparticles for use as an electrically conductive material capable of sintering at lower temperatures that is able to be used even with flexible printed substrates having low heat resistance, and a manufacturing method therefor. The coated silver nanoparticles of the present invention have a mean particle diameter of 30 nm or less and are coated with protective molecules amine, and are characterized in that the weight loss rate when heated to 160°C in thermogravimetric measurement is 30% or more. The coated silver nanoparticles of the present invention are also characterized in that a silver-colored sintered film can be formed by sintering at a temperature of 100°C or lower for 1 hour or less. These coated silver nanoparticles are manufactured by mixing a silver compound that forms metallic silver when decomposed by heating, an alkylamine and an alkyldiamine to prepare a complex compound, and by thermally decomposing the silver compound by heating the complex compound.