Coated Copper Particles via Thermal Decomposition
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Solution Overview
Problem
Existing methods for producing coated copper particles face challenges in achieving both excellent oxidation resistance and sintering properties, particularly at low thermal treatment temperatures and in low oxygen-concentration environments, due to issues such as rapid particle growth, aggregation, and surface oxidation.
Innovation Solution
A method involving a reaction mixture with copper formate, an amino alcohol, an aliphatic carboxylic acid, and a solvent, where the difference in solubility parameter (ΔSP) between the amino alcohol and solvent is 4.2 or more, allowing for thermal decomposition to form coated copper particles with a surface coated by aliphatic carboxylic acid, enabling efficient production with controlled particle size and improved sintering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper fine particles are used to replace gold or silver, then cost is reduced and conductivity is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent applies composite materials by coating copper fine particles with a protective layer comprising silane coupling agent and organometallic compound. This composite structure combines the high conductivity of copper with the oxidation resistance of the protective coating, resolving the contradiction between using copper for cost/conductivity while maintaining oxidation resistance.
Solution Approach 2:
The patent creates an inert environment by forming a protective film on the copper particle surface that acts as a barrier against oxygen. The silane coupling agent and organometallic compound form an inert protective layer that prevents oxygen from reaching the copper surface, effectively creating a local inert atmosphere around each particle.
2Reliability
If surface protecting agent is added to prevent oxidation, then oxidation resistance is improved, but sintering density deteriorates due to volume shrinkage
Solution Approach 1:
The patent changes the parameters of the protective agent by using a specific combination of silane coupling agent and organometallic compound in controlled amounts. The silane coupling agent is used at 0.01-5 wt% and organometallic compound at 0.1-10 wt% based on copper particle weight. These optimized parameters provide sufficient protection while minimizing volume shrinkage during sintering.
Solution Approach 2:
The silane coupling agent acts as an intermediary between the copper particle surface and the organometallic compound. It forms a bridging layer that provides oxidation protection while being more compatible with the sintering process, reducing the harmful volume shrinkage effect compared to using large amounts of protective agents alone.
3Temperature
If single-nanometer-sized particles are used to achieve melting point depression, then sintering temperature is reduced, but oxidation resistance deteriorates due to high surface activity
Solution Approach 1:
The patent applies composite materials by coating nanometer-sized copper particles with silane coupling agent and organometallic compound. This composite structure protects the highly active nanometer surface from oxidation while maintaining the low sintering temperature advantage of the small particle size.
Solution Approach 2:
The patent applies local quality by providing oxidation protection only at the particle surface through the protective coating, while the interior of the nanometer particles maintains their high surface activity and low melting point characteristics. This localized approach preserves the temperature advantage while adding oxidation resistance where needed.
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 method produces coated copper particles with excellent oxidation resistance and sintering properties, allowing for low-temperature sintering in a nitrogen-purged atmosphere, overcoming previous limitations in particle size distribution and environmental requirements.
Implementation Method 1
a complex compound formed in the reaction mixture
Implementation Method 2
subjecting a complex compound formed in the reaction mixture to thermal decomposition treatment to form metal copper
Implementation Method 3
having a surface coated with an aliphatic carboxylic acid
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A method for producing coated copper particles having a surface coated with an aliphatic carboxylic acid, wherein the method comprises obtaining a reaction mixture containing copper formate, an amino alcohol, an aliphatic carboxylic acid having an aliphatic group having 5 or more carbon atoms, and a solvent, and subjecting a complex compound formed in the reaction mixture to thermal decomposition treatment to form metal copper, wherein a ΔSP value, which is a difference in SP value between the amino alcohol and the solvent, is 4.2 or more.