Silver Microparticle Dispersion for Polar Solvent Conductive Films
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Solution Overview
Problem
Fine silver particles coated with organic protective materials have poor dispersibility in polar solvents, leading to increased viscosity and aggregation, making it difficult to form fine electrodes and circuits, and compatibility issues with resin binders in nonpolar solvents result in poor film quality.
Innovation Solution
A fine silver particle dispersing solution is developed using silver particles coated with amines having a carbon number of 8 to 12 and an average diameter of 100-300 nm, combined with an acrylic dispersing agent in a glycol ether solvent with a boiling point of 150-300 °C, enhancing dispersibility and low-temperature sinterability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fine silver particles coated with organic protective material (primary amine with carbon number 6 to 12) are used, then the particles are stable and easy to sinter at low temperature, but they aggregate in polar solvents and have poor dispersibility
Solution Approach 1:
The patent changes the carbon number parameter of the organic protective material from 6-12 to 13-19, which fundamentally alters the hydrophobicity-hydrophilicity balance of the coating. This parameter change enables the silver particles to achieve good dispersibility in polar solvents while maintaining stability, resolving the contradiction between particle stability and dispersibility.
2Ease of operation
If fine silver particles coated with organic protective material are dispersed in nonpolar solvent, then good dispersibility is achieved, but compatibility with resin binder deteriorates and film quality becomes poor
Solution Approach 1:
By changing the carbon number parameter of the organic protective material to 13-19, the patent shifts the solvent compatibility from nonpolar to polar. This allows the use of polar solvents that are compatible with resin binders, thereby resolving the contradiction between dispersibility and binder compatibility.
3Reliability
If fine silver particles are dispersed in polar solvent, then compatibility with resin binder is improved, but viscosity increases and particle aggregation occurs
Solution Approach 1:
The patent applies parameter change by selecting organic protective materials with carbon numbers 13-19, which have optimal amphiphilic characteristics. These coatings reduce surface tension and improve wetting properties, allowing particles to disperse uniformly in polar solvents without aggregation or excessive viscosity increase.
4Temperature
If average particle diameter is reduced to enhance sintering activity, then low-temperature sintering is achieved, but particle aggregation increases and dispersibility deteriorates
Solution Approach 1:
The patent creates a composite structure by coating fine silver particles with organic protective materials having carbon numbers 13-19. This composite approach allows the core silver particles to maintain small size for low-temperature sintering, while the organic coating provides steric stabilization and improves dispersibility, resolving the contradiction between sintering activity and dispersibility.
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 solution achieves excellent dispersibility of fine silver particles in polar solvents, enabling the formation of silver conductive films with low resistance when sintered at low temperatures, while maintaining stability and compatibility with resin binders.
Implementation Method 1
an acrylic dispersing agent of methacrylic acid butyl ester added to the glycol ether solvent
Implementation Method 2
a glycol ether solvent having a boiling point of 150 to 300 °C
Implementation Method 3
heated at a low temperature of about 100 to 200 °C to be burned to sinter the fine silver particles with each other to form a silver conductive film
Data Source
AI summary
There is produced a fine silver particle dispersing solution which contains: fine silver particles (the content of silver in the fine silver particle dispersing solution being 30 to 95 % by weight), which have an average primary particle diameter of greater than 100 nm and not greater than 300 nm and which are coated with an amine having a carbon number of 8 to 12, such as octylamine, serving as an organic protective material; a polar solvent (5 to 70 % by weight) having a boiling point of 150 to 300 °C; and an acrylic dispersing agent (5 % by weight or less with respect to the fine silver particles), such as a dispersing agent of at least one of acrylic acid ester and methacrylic acid ester.