Copper Particle Preparation via Cu2O Assembly and Two-Stage Reduction

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Solution Overview

Problem

Current methods for producing copper particles are complex, economically inefficient, and result in particles with poor crystallinity and susceptibility to oxidation, making them unsuitable for electronic materials.

Innovation Solution

A method involving the dissolution of a copper carboxyl compound and a copper salt in a solvent to create a copper(II) precursor solution, followed by the addition of a weak reducing agent to form spherical Cu2O assembly particles, which are then reduced to copper particles using a mild reducing agent, with the option of adding surfactants to control size and shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional copper particle making methods (mechanical grinding, co-precipitation, spraying, sol-gel, electrolysis) are used, then copper particles can be produced, but the process complexity increases and economical efficiency deteriorates

Engineering Contradiction:
Improvecopper particle qualityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the chemical parameters by using copper carboxyl compounds as precursors instead of conventional copper salts, and employs a two-stage reduction process with different reducing agents (hydrazine followed by sodium borohydride) to achieve better particle quality with controlled complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite approach by combining copper carboxyl compound precursor with specific reducing agents and additives to form a composite chemical system that produces high-quality copper particles while managing process complexity

Inventive Principle:
Principle #40Composite materials

2Productivity

If strong reducing agent (hydrazine-based) is used to reduce copper(II) precursor, then reduction reaction proceeds rapidly, but Cu2O particle size increases greatly and shape control becomes difficult

Engineering Contradiction:
Improvereduction reaction speedVSAvoidparticle size and shape control
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the reduction process into two distinct stages: first using hydrazine to reduce copper(II) to Cu2O, then using sodium borohydride to reduce Cu2O to copper particles. This segmentation allows control over particle size and shape while maintaining productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by first forming Cu2O particles with controlled morphology using hydrazine, then subsequently reducing them to copper particles. This preliminary formation step enables better control over final particle characteristics

Inventive Principle:
Principle #10Preliminary action

3Quantity of substance

If copper particles are produced with conventional methods, then copper particles are obtained, but they exhibit strong tendency to oxidize into CuO and show bad crystallinity, deteriorating electric conductivity

Engineering Contradiction:
Improvecopper particle productionVSAvoidoxidation resistance and crystallinity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the chemical environment parameters by using copper carboxyl compounds as precursors and employing a two-stage reduction process, which produces copper particles with better crystallinity and oxidation resistance while maintaining production efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses Cu2O as an intermediary substance in the two-stage reduction process. The copper carboxyl compound is first reduced to Cu2O, which then serves as the intermediate before final reduction to copper particles, improving product quality

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This method allows for the rapid, economical production of copper particles with good crystallinity and resistance to oxidation, suitable for use in electronic materials, while maintaining uniform size and shape.

Implementation Method 1

dissolving a copper carboxyl compound expressed by the following chemistry figure 1, or a carboxyl group-containing compound expressed by the following chemistry figure 2 and a copper salt, in a solvent to prepare a copper(II) precursor solution

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 2

putting a weak reducing agent with a standard reduction potential of -0.2 to -0.05V to the prepared copper(II) precursor solution to assemble a plurality of Cu 2 O fine particles

Methodology Applied
Scientific EffectReduction reaction: Reduction

Implementation Method 3

reducing the spherical Cu 2 O assembly particles into copper particles by using a reducing agent

Methodology Applied
Scientific EffectReduction reaction: Reduction

Data Source

PatentEP2190613B1Preparation method of copper particle composition
Publication Date: 2014.03.12 LG CHEM LTD
  • EP2190613B1 patent drawingFigure 1~2
  • EP2190613B1 patent drawingFigure 3~4
  • EP2190613B1 patent drawingFigure 5~6

AI summary

A preparation method of a copper particle composition includes dissolving a copper carboxyl compound, or a carboxyl group-containing compound and a copper salt, in a solvent to prepare a copper(II) precursor solution; putting a weak reducing agent with a standard reduction potential of -0.2 to -0.05V to the prepared copper(II) precursor solution to assemble a plurality of Cu2O fine particles having an average diameter of 1 to 100 nm with a standard deviation of 0 to 10 %, thereby forming spherical Cu2O assembly particles having an average diameter of 0.1 to 10 μm with a standard deviation of 0 to 40 %; reducing the spherical Cu2O assembly particles into copper particles by using a reducing agent; and separating the copper particles from the result product. Thus, copper particles can be produced fast, economically, and the obtained copper particles have good crystallinity and good resistance against oxidation.