Silver Powder Particle Control for Lower-Resistance Conductive Paste
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Solution Overview
Problem
There is a demand for further reduction of line resistance in conventional conductive pastes used for forming conduction patterns and electrodes.
Innovation Solution
A silver powder with specific particle size distribution, shape, and ignition loss, produced through a method involving a reduction step, surface treatment, and flaking process, is used to create a conductive paste that reduces line resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silver powder is used in conductive paste, then the paste can be formed and fired to create conduction patterns, but the line resistance remains high and cannot be reduced further
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution of silver powder within specific ranges (D10: 1-3 μm, D50: 3-6 μm, D90: 6-12 μm) and particle shape parameters (aspect ratio 3-10, circularity 0.3-0.7). These controlled parameter changes enable dense particle packing during sintering, which directly reduces line resistance while maintaining manufacturing feasibility.
Solution Approach 2:
The patent creates a composite particle size distribution system that combines multiple particle size ranges and shapes within the silver powder. This composite approach allows smaller particles to fill voids between larger particles, achieving denser packing and lower resistance without sacrificing the overall structural integrity needed for conductive paste formation and firing.
2Reliability
If silver powder with optimized particle size distribution is used, then line resistance can be reduced through dense packing, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for particle size (D10: 1-3 μm, D50: 3-6 μm, D90: 6-12 μm) and shape (aspect ratio 3-10, circularity 0.3-0.7) that balance manufacturing feasibility with performance. These parameter specifications provide clear manufacturing targets while allowing sufficient tolerance for production variations, thus reducing line resistance without excessive precision requirements.
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 silver powder achieves dense packing of particles during sintering, resulting in reduced line resistance and improved conductivity.
Implementation Method 1
a reduction step of adding a reductant to a silver ammine complex aqueous solution to obtain a first liquid
Implementation Method 2
a surface treatment agent addition step of adding a surface treatment agent to the first liquid to obtain a second liquid
Implementation Method 3
a flaking step of stirring the first powder, a lubricant, and media inside of a vessel to obtain a second silver powder in which the first silver powder has undergone flattening
Implementation Method 4
The silver powder achieves dense packing of particles during sintering, resulting in reduced line resistance and improved conductivity
Data Source
AI summary
A method of producing a silver powder includes: adding a reductant to a silver ammine complex aqueous solution to obtain a first liquid; adding a surface treatment agent, in an amount of 0.05 to 0.15 wt % relative to weight of silver contained in the silver ammine complex aqueous solution, to the first liquid to obtain a second liquid; obtaining a first silver powder from the second liquid and drying; and stirring the first powder, a lubricant, and media inside of a vessel to obtain a second silver powder. A specific surface area diameter is 1.3 to 2.0 μm. A diameter at a cumulative value of 50% in a volume-based particle size distribution is 1.5 to 3 times the specific surface area diameter. Additive amounts of the lubricant and the surface treatment agent are, in total, 0.1 to 0.4 wt % relative to weight of silver in the first silver powder.