Flaky Silver Powder Morphology for Conductive Paste Printability
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Solution Overview
Problem
Existing flaky silver powders face challenges in maintaining low volume resistivity and continuous printability while reducing silver content in electrically conductive pastes, which are crucial for producing electrodes and circuits using printing technology.
Innovation Solution
A flaky silver powder with a tapped density of 0.8 g/mL to 1.9 g/mL, a cumulative 50th percentile particle diameter of 2 μm to 7 μm, and a controlled aspect ratio, produced through a flaking process that adjusts the volume ratio of spherical silver particles during collision with media to achieve optimal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the silver content in electrically conductive paste is reduced to lower cost, then the cost decreases, but the volume resistivity increases and electric conductivity deteriorates
Solution Approach 1:
The patent changes the physical parameters of silver particles by controlling the aspect ratio (length-to-thickness ratio) to be 5 or more, and specific surface area to be 0.5 m²/g or more. These parameter changes enable better particle packing and contact at reduced silver content, maintaining electrical conductivity while reducing material usage.
Solution Approach 2:
The patent creates a composite structure where flaky silver particles with high aspect ratio form a percolating network within the paste matrix. This composite arrangement allows efficient electrical pathways to form with less silver material, resolving the contradiction between reduced silver content and maintained conductivity.
2Reliability
If flaky silver powder with high tapped density is used to increase filling ratio, then the volume resistivity decreases, but the particle size distribution becomes difficult to control
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: tapped density (2.0-4.5 g/mL), specific surface area (0.5 m²/g or more), and aspect ratio (5 or more). This multi-parameter control approach maintains particle size distribution precision while achieving the high filling ratio needed for low volume resistivity.
3Reliability
If flaky silver powder is used to increase contact area between particles, then the electrical conductivity improves, but the continuous printability deteriorates due to particle aggregation
Solution Approach 1:
The patent optimizes the balance between specific surface area (0.5 m²/g or more for conductivity) and particle morphology (aspect ratio ≥5) to prevent excessive aggregation. This parameter optimization ensures particles maintain good contact for conductivity while preserving paste flowability for continuous printing.
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 enables electrically conductive pastes with excellent continuous printability and low volume resistivity, suitable for forming fine lines without short-circuiting or clogging, thus enhancing the production of electrodes and circuits.
Implementation Method 1
a flaking step in which spherical silver powder is allowed to collide with media to flake the spherical silver powder
Data Source
AI summary
To provide a flaky silver powder having a tapped density of from 0.8 g/mL to 1.9 g/mL, and a cumulative 50th percentile particle diameter (D50) of from 2 μm to 7 μm, where the cumulative 50th percentile particle diameter (D50) is measured by laser diffraction or laser scattering particle size analysis.