Coated Silver Particle Corrosion Resistance Sintering
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Solution Overview
Problem
Silver particles have low resistance to corrosion by sulfide gases and lack stability in grain size and sintering properties, limiting their application in conductive compositions.
Innovation Solution
Coated silver particles with a silver core and a surface coating of aliphatic carboxylic acid molecules at a density of 2.5 to 5.2 molecules/nm², produced through a thermal decomposition method using a silver carboxylate and amino alcohol complex, enhance corrosion resistance, grain-size stability, and sintering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If silver particles are used without coating, then excellent oxidation resistance is achieved, but corrosion resistance against sulfide gas is poor
Solution Approach 1:
An organic coating layer comprising long-chain aliphatic amine and/or aliphatic carboxylic acid is introduced as an intermediary substance between the silver core particles and the corrosive environment. This coating layer acts as a protective barrier that prevents direct contact between sulfide gas and the silver surface, thereby improving corrosion resistance while maintaining grain-size stability through controlled adsorption characteristics
Solution Approach 2:
The invention creates a composite structure consisting of a silver core particle and an organic coating layer. This composite material combines the excellent oxidation resistance of silver with the protective properties of the organic coating, achieving both improved corrosion resistance and grain-size stability simultaneously
2Object-affected harmful factors
If organic coating is applied to improve corrosion resistance, then sintering properties may deteriorate due to difficulty in removing the coating
Solution Approach 1:
The invention carefully selects and controls the parameters of the organic coating, specifically using long-chain aliphatic amines and/or carboxylic acids with specific molecular structures. These parameter choices ensure the coating provides adequate corrosion protection while maintaining sufficient thermal decomposability during sintering, allowing the coating to be removed at appropriate temperatures without compromising sintering properties
Solution Approach 2:
The organic coating layer undergoes phase transition through thermal decomposition during the sintering process. The coating material is selected to decompose at temperatures compatible with the sintering process, transitioning from a protective solid coating to gaseous decomposition products, thereby eliminating the coating's interference with sintering while having provided corrosion protection during handling and application
3Ease of manufacture
If particle diameter is reduced to improve sintering properties, then oxidation resistance may be compromised due to increased surface area
Solution Approach 1:
The organic coating layer serves as an intermediary protective barrier on the surface of fine silver particles. Even though fine particles have high surface area-to-volume ratio that would normally increase oxidation susceptibility, the coating layer blocks direct interaction between oxygen and the silver surface, maintaining oxidation resistance despite the reduced particle size and increased surface area
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 coated silver particles exhibit excellent corrosion resistance, stability, and sintering properties, improving the performance of conductive compositions and conductive layers in applications like wiring lines and conductor layers.
Implementation Method 1
a step (A2) of thermally decomposing a complex compound formed in the reaction solution and thereby generating metallic silver
Implementation Method 2
a plurality of aliphatic carboxylic acid molecules disposed on a surface of the silver core particle
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A coated silver particle (20) according to the present invention contains a silver core particle (21), and a plurality of aliphatic carboxylic acid molecules (22) absorbed to a surface of the silver core particle (21) at a density of 2.5 to 5.2 molecules per square nanometer (nm2). A carbon number of an aliphatic group of the aliphatic carboxylic acid molecule (22) is preferably 5 to 26. When an arithmetical average value and a standard deviation of primary particle diameters are represented by DSEM and SD, respectively, DSEM is preferably 0.02 to 5.0 µm and a particle diameter variation rate defined by a general formula SD/DSEM is preferably 0.01 to 0.5.