Surface-Coated Copper Filler for Conductive Compositions
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Solution Overview
Problem
Copper fillers in conductive compositions suffer from inadequate oxidation resistance, leading to increased volume resistivity and reduced conductivity due to copper oxide formation, which is not sufficiently improved by existing coatings like aliphatic monocarboxylic acids.
Innovation Solution
A surface-coated copper filler with a first layer of an amine compound and a second layer of aliphatic monocarboxylic acid, where the amine compound is chemically or physically bonded to the copper particle and the aliphatic monocarboxylic acid is bonded to the amine compound via electrostatic interaction, enhancing oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper particles are used as filler in conductive composition, then cost is reduced and specific volume resistance is lowered, but oxidation resistance is insufficient leading to high volume resistivity of hardened product
Solution Approach 1:
The invention applies a multi-layer composite coating structure on copper particles consisting of: (1) a first coating layer of aliphatic monocarboxylic acid with 8-20 carbon atoms providing basic corrosion protection and dispersibility, (2) a second coating layer of amine compound forming strong coordinate bonds with copper surface for enhanced oxidation resistance, and (3) optionally a third coating layer of silica or aluminum oxide providing mechanical protection and environmental stability. This composite structure synergistically addresses oxidation resistance while maintaining low volume resistivity.
Solution Approach 2:
The invention specifies precise parameter ranges for optimal performance: aliphatic monocarboxylic acid with 8-20 carbon atoms (balancing hydrophobicity and adhesion), amine compound with specific molecular weight and nitrogen content (5-20% by mass), and controlled coating thickness (1-100 nm). These parameter optimizations ensure the coating provides sufficient oxidation protection while maintaining electrical conductivity through the hardened product.
2Stability of the object's composition
If copper particles are coated with aliphatic monocarboxylic acid, then dispersibility is improved, but oxidation resistance is not sufficiently improved and particles are readily oxidized in atmospheric air
Solution Approach 1:
The invention creates a multi-functional composite coating where the aliphatic monocarboxylic acid layer provides dispersibility and hydrophobic protection, while the amine compound layer forms strong coordinate bonds with copper surface atoms, creating a protective barrier against oxidation. The synergistic combination of these two materials achieves both good dispersibility and excellent oxidation resistance, overcoming the limitation of single-material coatings.
Solution Approach 2:
The coating structure provides different functional properties at different layers: the outer aliphatic monocarboxylic acid layer provides hydrophobicity and dispersibility, while the inner amine compound layer provides strong chemical bonding and oxidation protection. This localized functional differentiation allows each layer to optimize its specific function while working together to solve the overall problem of oxidation resistance and dispersibility.
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 surface-coated copper filler exhibits excellent oxidation resistance and low volume resistivity, enabling the formation of conductive products with high conductivity.
Implementation Method 1
a first coating layer containing an amine compound, which is bonded to copper on a surface of the copper particle via a chemical bond and/or a physical bond
Implementation Method 2
a first coating layer containing an amine compound, which is bonded to copper on a surface of the copper particle via a chemical bond and/or a physical bond
Implementation Method 3
a second coating layer containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms, which is bonded to the amine compound via a chemical bond
Data Source
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AI summary
There are provided a surface-coated copper filler having an excellent oxidation resistance for use in a conductive composition, a method for producing the surface-coated copper filler, and a conductive composition containing the surface-coated copper filler. The surface-coated copper filler comprises: a copper particle; a first coating layer containing an amine compound, which is bonded to copper on a surface of the copper particle via a chemical bond and/or a physical bond; and a second coating layer containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms, which is bonded to the amine compound via a chemical bond. The amine compound is represented by the following formula (1): wherein m is an integer of 0 to 3, n is an integer of 0 to 2, m is 0 to 3 when n is 0, and m is 1 to 3 when n is 1 or 2.