Spherical Silver Powder for Fine-Line Conductive Paste Printing
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Solution Overview
Problem
Existing silver powders used in conductive pastes struggle to achieve fine line printability due to non-uniform particle size distribution and aggregation, limiting their application in compact electronic components and conductive patterns.
Innovation Solution
A method of producing spherical silver powder by controlling particle size distribution and dispersibility through precise addition of a reductant from multiple directions within a channel, ensuring (D90-D10)/D50 < 1 and D50/DBET between 0.9 and 1.2, with D50 between 0.2 μm and 3.5 μm, and a BET specific surface area between 0.17 m2/g and 3.23 m2/g.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional silver powder production methods are used, then silver powder can be produced, but the particle size distribution is non-uniform and aggregation occurs, resulting in poor fine line printability
Solution Approach 1:
The invention segments the reductant addition process into multiple spatial locations within the channel (first addition location and second addition location downstream). This segmented approach enables staged reduction reactions that control nucleation and particle growth separately, resulting in uniform particle size distribution and preventing aggregation, thereby improving both manufacturing precision and fine line printability
Solution Approach 2:
The invention introduces a spatial dimension to the reductant addition process by adding reductant at multiple positions along the channel length rather than at a single point. This dimensional approach allows sequential control of the reduction reaction, creating uniform nuclei that grow into monodisperse spherical particles with excellent fine line printability
2Volume of moving object
If silver powder with small particle diameter is used, then compactization of electronic components is enabled, but dispersibility in organic vehicle deteriorates
Solution Approach 1:
The invention changes the physical parameters of silver powder by controlling the reduction process to produce spherical particles with narrow size distribution (D10-D90 within 0.5-5 μm). The spherical shape and uniform size enhance both compactization capability and dispersibility in organic vehicle, as the regular geometry prevents aggregation while maintaining small effective volume
Solution Approach 2:
The invention produces spherical silver particles through controlled reduction in flowing solution. The spherical shape reduces interparticle adhesion and improves flow characteristics, enabling both small particle diameter for compactization and excellent dispersibility in the organic vehicle medium
3Manufacturing precision
If multi-directional reductant addition is implemented, then particle size distribution is controlled, but device complexity increases
Solution Approach 1:
The invention uses fluid flow dynamics in a simple channel to achieve multi-directional mixing and staged reductant addition. The flowing silver complex solution naturally distributes the reductant throughout the channel cross-section, eliminating the need for complex mechanical mixers or multi-point injection systems while maintaining precise particle size control
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 spherical silver powder exhibits excellent fine line printability and dispersibility, facilitating low-temperature sintering and high-density patterning in conductive pastes for electronic components.
Implementation Method 1
quantitatively and continuously reducing the silver complex in a reaction liquid obtained by mixing the silver solution and the reductant solution inside the channel to obtain a silver powder
Implementation Method 2
causing reduction precipitation of silver particles
Implementation Method 3
silver nitrate aqueous solution and ammonia water being mixed and reacted to obtain a silver ammine complex aqueous solution
Data Source
AI summary
Provided is a spherical silver powder that can bring about excellent fine line printability when used in a conductive paste or the like. The spherical silver powder has a diameter D10 at a volume-based cumulative value of 10%, a diameter D50 at a volume-based cumulative value of 50%, and a diameter D90 at a volume-based cumulative value of 90% according to laser diffraction that satisfy a formula: (D90−D10)/D50<1, and has a ratio D50/DBET of the D50 relative to a BET diameter DBET of not less than 0.90 and not more than 1.20.