Flake-like Silver Powder Wet Reduction for Conductive Paste
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Solution Overview
Problem
Existing methods for producing flat silver particles result in excessively small average particle sizes, leading to increased contact resistance, handling difficulties, and challenges in achieving conduction when incorporated into conductive pastes, due to the use of gelatin and lengthy production times.
Innovation Solution
A flaky-like silver powder is produced using a wet reduction method with nitric acid and organic acid, achieving a predetermined average particle size and bulk density, allowing for easier handling and improved electrical characteristics by adjusting the particle shape and surface treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If wet reduction method with gelatin is used to produce flat silver particles, then particle shape control is improved, but average particle size becomes excessively small and production time increases
Solution Approach 1:
The patent changes the chemical parameters of the reduction process by replacing gelatin with a different reducing agent system and adjusting pH conditions. This parameter change allows achieving the desired flat particle shape while significantly reducing production time and avoiding excessively small particle sizes. The new method uses controlled reduction kinetics to form flat particles more efficiently.
2Shape
If wet reduction method with gelatin is used to produce flat silver particles, then particle shape control is improved, but average particle size becomes excessively small leading to increased contact resistance
Solution Approach 1:
By changing the reducing agent from gelatin-based system to an alternative chemical reducing system with controlled pH and temperature parameters, the patent achieves optimal particle size distribution. The new parameters produce flat particles with sufficient size to reduce contact resistance while maintaining the desired shape, thereby improving electrical conduction reliability in conductive pastes.
3Volume of moving object
If flat silver particles with small size are produced, then surface area to volume ratio is improved, but handling difficulty increases
Solution Approach 1:
The patent optimizes the reduction parameters including pH, temperature, and reducing agent concentration to produce flat silver particles with controlled size distribution. The parameters are tuned to achieve particles that are small enough for good surface area utilization but large enough for easy handling and processing in conductive paste manufacturing, eliminating the handling difficulties associated with excessively fine particles.
4Shape
If flat silver particles are produced using conventional methods, then particle morphology is improved, but bulk density becomes excessive
Solution Approach 1:
By changing the reduction parameters and using a different chemical system without gelatin, the patent produces flat silver particles with optimized morphology. The particles maintain their flat shape for good conductive network formation while achieving lower bulk density through controlled particle formation and reduced aggregation, improving the overall performance of conductive pastes.
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 flaky-like silver powder enables efficient production of conductive pastes with satisfactory electrical characteristics and reduced bulk density, facilitating better conduction and mechanical strength even with a smaller amount of incorporation.
Implementation Method 1
a flaky-like silver powder obtained by a wet reduction method
Data Source
AI summary
Provided are a flaky-like silver powder having a low bulk density as well as a predetermined average particle size (D50) and the like, which is obtainable by using a predetermined wet reduction method, a conductive paste obtainable using such a flaky-like silver powder, and a method for producing such a flaky-like silver powder.Disclosed are a flaky-like silver powder obtainable by a wet reduction method, a conductive paste obtainable using a flaky-like silver powder, and a method for producing a flaky-like silver powder, in which the average particle size (D50) as an equivalent circle diameter obtainable when the flaky-like silver powder particles are viewed planarly is adjusted to a value within the range of 1.1 to 30 μm, the thickness of the flaky-like silver powder particles is adjusted to 0.01 to 2 μm, and the bulk density of the flaky-like silver powder is adjusted to a value within the range of 0.1 to 4 g/cm3.