Copper Nanoparticles with Alcohol Protective Layer for Low-Temperature Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods fail to produce copper nanoparticles with an average diameter of 10 nm or less that can be sintered at low temperatures, are highly dispersible, and stable, due to issues with oxidation and aggregation, and existing protective layers cannot be completely removed during low-temperature sintering.
Innovation Solution
Copper nanoparticles with a central copper single crystal and a protective layer containing C3-6 primary or secondary alcohols or derivatives, which allows for low-temperature sintering and stability, are developed, along with a method for preserving these nanoparticles at room temperature using a C4-14 alkane solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper nanoparticles with small particle diameter (10 nm or less) are used to reduce sintering temperature, then low-temperature sintering is achieved, but the nanoparticles are highly reactive and aggregate easily, making them unstable and difficult to preserve
Solution Approach 1:
The patent introduces a protective layer comprising C3-6 primary or secondary alcohols as an intermediary substance that coats the copper nanoparticle surface. This protective layer acts as a mediator that prevents direct contact between copper nanoparticles and oxygen, thereby suppressing oxidation and aggregation while maintaining the small particle diameter needed for low-temperature sintering. The protective layer is specifically designed to be removable at low temperatures to enable subsequent sintering.
Solution Approach 2:
The patent changes the chemical composition parameters of the protective layer by selecting specific C3-6 primary or secondary alcohols (such as n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol) with controlled carbon chain lengths. This parameter optimization ensures the protective layer provides sufficient stability during storage but can be completely removed during low-temperature sintering (150°C or less), resolving the contradiction between stability and sinterability.
2Reliability
If conventional protective layers are used to prevent aggregation, then dispersion stability is improved, but the protective layers cannot be completely removed during low-temperature sintering, reducing electrical conductivity
Solution Approach 1:
The patent optimizes the chemical parameters of the protective layer by selecting C3-6 primary or secondary alcohols with specific molecular weights and boiling points. These parameters are carefully chosen so that the protective layer remains stable at room temperature for storage but decomposes or evaporates completely at sintering temperatures of 150°C or less, enabling both stable preservation and complete removal without residue that would affect conductivity.
Solution Approach 2:
The patent utilizes phase transition (evaporation or decomposition) of the C3-6 alcohol-based protective layer at low temperatures during sintering. The protective layer transitions from a stable liquid/film state during storage to a gaseous state or decomposed products during heating, enabling complete removal without requiring high temperatures that would damage heat-sensitive substrates.
3Ease of operation
If copper nanoparticles are preserved at room temperature for long periods, then storage convenience is improved, but oxidation and aggregation occur more easily
Solution Approach 1:
The C3-6 primary or secondary alcohol forms a protective intermediary layer on the copper nanoparticle surface that acts as a physical barrier between the copper and oxygen in the air. This intermediary layer allows the nanoparticles to be stored at convenient room temperatures without requiring special conditions, while effectively preventing oxidation and aggregation during long-term storage.
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 copper nanoparticles can be sintered at 150°C or less, forming fine metal wires on heat-sensitive substrates like paper or plastic, while maintaining high conductivity and stability, and can be preserved for long periods at room temperature.
Implementation Method 1
a protective layer surrounding the central portion; (2) the protective layer containing at least one member selected from the group consisting of C3-6 primary alcohols, C3-6 secondary alcohols, and derivatives thereof
Implementation Method 2
copper nanoparticles that can be sintered at a low temperature, a method for producing the copper nanoparticles, a copper nanoparticle dispersion, and copper nanoink; and also relates to a method for preserving monodisperse nano-sized copper nanoparticles having high dispersion stability, and a method for sintering the copper nanoparticles
Implementation Method 3
heated at a low temperature to thereby remove the organic substance from the surface of the metal nanoparticles, and to form metal bonds between the metal nanoparticles
Data Source
AI summary
An object of the present invention is to provide copper nanoparticles that suppress the oxidation of copper, have an average particle diameter of 10 nm or less and therefore undergo a remarkable reduction in the melting point, are highly dispersible, can be sintered at a low temperature, allow the removal of the protective layer during low-temperature sintering at 150° C. or less, and can be suitably used as a conductive copper nanoink material; and to also provide a method for preserving copper nanoparticles, whereby the copper nanoparticles can be stably preserved at room temperature for a long period of time, and can be transported.The present invention provides copper nanoparticles each having a central portion comprising a copper single crystal, and a protective layer surrounding the central portion;(1) the copper nanoparticles having an average particle diameter of 10 nm or less;(2) the protective layer containing at least one member selected from the group consisting of C3-6 primary alcohols, C3-6 secondary alcohols, and derivatives thereof; and(3) the protective layer having a boiling point or thermal decomposition point of 150° C. or less.