Silver Nanoparticle Powder Synthesis for Low-Temperature Conductive Paste
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing silver-containing powders with nanometer-sized silver particles face challenges such as low metal content, high temperature requirements for conductivity, and poor storage stability, especially when used in conductive pastes for plastic substrates with low thermal resistance.
Innovation Solution
A silver-containing powder is produced by reducing silver compounds in an aqueous medium with a polymer compound having polyethyleneimine and polyethylene glycol segments, which enhances dispersibility and stability, allowing for high silver content and low-temperature fusion, and is applied to plastic substrates using a conductive paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal nanoparticles are coated with protective agents and dispersed in solvent to form colloidal dispersion to prevent fusion, then storage stability is improved, but transportation and storage convenience is worsened due to liquid form requirements
Solution Approach 1:
The patent transforms the physical state of metal nanoparticles from liquid colloidal dispersion to solid powder form through controlled drying processes. This phase transition enables the material to maintain storage stability while gaining transportation and storage convenience of solid materials.
Solution Approach 2:
The patent applies protective coatings to metal nanoparticles before the drying process to prevent fusion during the transition from liquid to solid state. This preliminary protection ensures that when the solvent is removed, the particles remain separated and stable in the dry powder form.
2Ease of operation
If powder containing metal nanoparticles is obtained by simply distilling off and evaporating dispersion solvent, then transportation and storage convenience is improved, but storage stability is worsened due to particle fusion and adhesion
Solution Approach 1:
The patent applies protective coatings to metal nanoparticles before evaporation to prevent particle fusion and adhesion that would otherwise occur during solvent removal. This preliminary protection enables successful transition to dry powder form while maintaining stability.
Solution Approach 2:
The protective coating acts as an intermediary substance between metal nanoparticles, preventing direct contact and fusion during the evaporation and drying processes. This intermediary layer maintains particle separation in the final dry powder form.
3Manufacturing precision
If dialysis method is employed to remove counterions from dispersed powders, then purity is improved, but production cycle and cost are worsened
Solution Approach 1:
The patent extracts or removes counterions and excess reagents through alternative methods such as centrifugation, filtration, or controlled precipitation during the synthesis process, avoiding the time-consuming dialysis step while still achieving sufficient purity for industrial applications.
Solution Approach 2:
The patent skips the dialysis step entirely by designing a synthesis process that either minimizes counterion formation or enables their removal through faster alternative methods, thus rushing through the purification process more efficiently.
4Stability of the object's composition
If alkali-soluble polymer is used in metal fine particle production, then dispersibility is improved, but environmental load is worsened due to large amount of alkali aqueous solution required
Solution Approach 1:
The patent changes the pH parameter from highly alkaline (pH 12) to milder conditions, and/or replaces alkali-soluble polymers with polymers soluble in different conditions, thereby reducing the amount of alkali aqueous solution required and decreasing environmental load while maintaining dispersibility.
Solution Approach 2:
The patent uses polymers and reagents that can be easily removed or decomposed, reducing the need for extensive waste treatment. The system is designed so that harmful substances are minimized or made biodegradable/easily treatable.
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 resulting silver-containing powder achieves high silver content (>95% by mass) with excellent storage stability and redispersibility, enabling conductive films on various substrates, including those with low thermal resistance, and provides good adhesiveness and conductivity at low temperatures.
Implementation Method 1
reducing silver compounds in an aqueous medium with a polymer compound having polyethyleneimine and polyethylene glycol segments
Implementation Method 2
polymer compound having polyethyleneimine and polyethylene glycol segments, which enhances dispersibility and stability
Implementation Method 3
allowing for high silver content and low-temperature fusion
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to powder containing silver nanoparticles having an average particle size of 2 to 50 nm in an amount of 95% or more by mass and to applications of the powder. Silver-containing powder containing the silver nanoparticles is obtained by reducing a silver compound in the presence of a compound obtained by bonding polyethylene glycol to polyethyleneimine having a certain molecular weight and then by performing a concentration step and a drying step. A plastic substrate is obtained by directly applying a conductive paste that uses the powder on a plastic substrate and by performing drying.