Metal Nanoparticle Bonding Material with Organic Coating
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Solution Overview
Problem
Conventional bonding materials using metal nanoparticles alone fail to achieve sufficient bonding strength due to challenges in mixing nanoparticles and microparticles in a desired ratio, leading to aggregation and instability, which affects the bonding process.
Innovation Solution
A bonding material comprising silver nanoparticles with an average diameter of 10.0 nm to 100 nm, coated with a carboxylic acid having 6 to 8 carbon atoms, dispersed in a polar solvent with a dispersant, and optionally mixed with other metal nanoparticles coated with different organic substances, to enhance stability and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If metal nanoparticles are used alone for bonding, then the bonding process can be simplified, but sufficient bonding strength cannot be achieved
Solution Approach 1:
The patent changes the surface parameters of metal nanoparticles by coating them with organic compounds having specific carbon chain lengths (2-8 carbons). This surface modification alters the interfacial properties and melting behavior, enabling nanoparticles to achieve sufficient bonding strength while maintaining process simplicity. The organic coating acts as a mediator that facilitates particle fusion at lower temperatures without requiring complex multi-component systems.
2Strength
If microparticles and nanoparticles are mixed in a desired ratio, then bonding strength can be improved, but mixing stability becomes difficult to maintain
Solution Approach 1:
The patent applies homogeneity by coating all metal particles (both nano and micro) with the same type of organic compound. This uniform surface treatment ensures consistent interfacial properties throughout the mixture, preventing segregation and aggregation. The homogeneous organic coating creates stable dispersions and maintains particle distribution during storage and processing, eliminating the instability associated with mixed particle systems.
3Temperature
If metal nanoparticles are used for bonding, then low temperature bonding is achieved, but oxidation deterioration may occur
Solution Approach 1:
The patent employs organic compounds with short thermal stability (low decomposition temperature) as protective coatings on metal nanoparticles. These organic layers serve as sacrificial protective barriers that decompose at relatively low temperatures, releasing the metal particles for bonding while having already performed their oxidation protection function during storage and handling. The decomposition of these short-lived organic protectants enables the metal to bond without requiring long-term oxidation resistance at high temperatures.
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 bonding material achieves high bonding strength and stability, with the organic coating decomposing at low temperatures, allowing for a bonding layer with properties comparable to bulk metal, even at elevated temperatures, while preventing oxidation and ensuring reliable adhesion.
Implementation Method 1
the organic substance is decomposed at a low temperature
Implementation Method 2
a polar solvent in an amount of 5 to 20% by mass with respect to the silver nanoparticles
Implementation Method 3
a dispersant in an amount of 0.1% by mass or more and 1.0% by mass or less with respect to the total amount
Implementation Method 4
metal nanoparticles are melted by heating at relatively low temperatures (up to about 350°C) and bound to form metal bonding
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
In a bonding material using nanoparticles and a bonding method, use in combination with microparticles is proposed. However, there is the problem in which it is not easy to uniformly mix the nanoparticles and the microparticles. The present invention uses a bonding material including metal nanoparticles having an average particle diameter of 100 nm or less and a surface coated with an organic substance having 6 to 8 carbon atoms, and a polar solvent in an amount of 5 to 20% by mass with respect to a powder of the metal nanoparticles, and objects to be bonded with the bonding material interposed therebetween are fired at 200 to 350°C under pressure. Thus, the metal nanoparticles are melted and returned to a bulk material, and therefore a bonding layer of the bulk material can be formed at a low temperature equal to or lower than a melting point.