Silver-Bismuth Powder for High-Temperature Conductive Paste
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive pastes using copper or silver-plated copper powders face issues with oxidation at high temperatures, leading to reduced conductivity and increased costs, while existing silver-bismuth solutions have limitations in solder wettability and volume resistivity when used in oxidizing atmospheres above 500°C.
Innovation Solution
A silver-bismuth powder with a mass ratio of 95:5 to 40:60, particle diameters between 0.1 μm to 10 μm, and an oxygen content of 5.5% or less, produced through an atomization process, which maintains conductivity and solder wettability even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper powder is used in conductive paste for high-temperature burning, then cost is reduced, but conductivity is reduced due to oxidation
Solution Approach 1:
The invention uses a composite material structure with a copper core and silver plating layer. The copper core provides cost advantage and electrical conductivity, while the silver plating layer provides oxidation resistance at high temperatures. This composite structure resolves the contradiction between cost reduction and maintaining conductivity under oxidizing conditions.
2Reliability
If silver is used in conductive paste for high-temperature burning, then conductivity is maintained, but cost is increased
Solution Approach 1:
The silver-plated copper powder creates a composite material where only the surface layer is silver, dramatically reducing the overall silver content compared to pure silver powder. This maintains the oxidation resistance and conductivity benefits of silver while significantly reducing cost.
Solution Approach 2:
The silver plating is applied only on the surface of the copper powder particles, providing oxidation protection exactly where it is needed (at the particle surface exposed to oxidizing atmosphere) while the bulk material remains copper for cost efficiency.
3Quantity of substance
If silver-plated copper powder is used in conductive paste, then cost is reduced compared to pure silver, but conductivity is reduced when burned at high temperatures
Solution Approach 1:
The silver-plated copper powder maintains its composite structure through high-temperature burning, with the silver layer protecting the copper core from oxidation. This preserves both the cost advantage and the conductivity that would be lost with pure copper.
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-bismuth powder achieves low volume resistivity and excellent solder wettability, enabling its use in high-temperature oxidizing atmospheres, reducing costs, and facilitating the production of conductive films with improved performance.
Implementation Method 1
silver; and bismuth, wherein a mass ratio (silver:bismuth) of the silver to the bismuth is 95:5 to 40:60, wherein a cumulative 50% point of particle diameter (D50) of the silver-bismuth powder in a volume-based particle size distribution thereof as measured by a laser diffraction particle size distribution analysis is 0.1 μm to 10 μm, and wherein an oxygen content of the silver-bismuth powder is 5.5% by mass or less
Implementation Method 2
produced through an atomization process
Data Source
AI summary
To provide a silver-bismuth powder, which includes: silver; and bismuth, wherein a mass ratio (silver:bismuth) of the silver to the bismuth is 95:5 to 40:60, wherein a cumulative 50% point of particle diameter (D50) of the silver-bismuth powder in a volume-based particle size distribution thereof as measured by a laser diffraction particle size distribution analysis is 0.1 μm to 10 μm, and wherein an oxygen content of the silver-bismuth powder is 5.5% by mass or less.