Surface-Treated Copper Powder Paste for MLCC Electrodes
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Solution Overview
Problem
Current methods for producing metal powder pastes for internal electrodes in multilayer ceramic capacitors face challenges with sintering delay property, operability, and productivity, particularly with small particle sizes leading to aggregation and reduced electrical conductivity.
Innovation Solution
A metal powder paste is created by mixing a metal powder with an aqueous solution of an amino group-containing coupling agent, followed by washing and dispersing in a solvent with a carboxyl or amino group-containing organic compound, which prevents aggregation and enhances sintering delay property.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the particle size of metal powder is reduced to achieve miniaturization of capacitors, then the capacitor size is reduced, but the melting point lowers causing cracks in electrode layers during firing
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance that forms a surface treatment layer on the metal powder particles. This coupling agent layer acts as a mediator that prevents direct contact and bonding between metal particles at high temperatures, thereby preventing crack formation while allowing the use of fine particles for miniaturization.
Solution Approach 2:
The invention creates a composite structure by forming a surface treatment layer on the metal powder particles. The composite consists of the metal powder core and the silane coupling agent shell, which together provide both the electrical conductivity of the metal and the high-temperature stability of the coupling agent, preventing particle bonding during firing.
2Volume of moving object
If the particle size of metal powder is reduced, then miniaturization is achieved, but aggregation occurs reducing electrical conductivity
Solution Approach 1:
The silane coupling agent serves as an intermediary that prevents direct aggregation between metal powder particles. The coupling agent molecules adsorb onto particle surfaces and create steric hindrance, maintaining particle dispersion and ensuring electrical conductivity pathways are preserved even with fine particles.
Solution Approach 2:
The invention changes the surface properties of the metal powder particles by applying a surface treatment with silane coupling agent. This parameter change in surface chemistry prevents aggregation while maintaining the electrical functionality, allowing fine particles to be used without conductivity loss.
3Reliability
If a dielectric particle or glass frit is added to reduce contact points between Cu powder particles, then sintering delay is improved, but the particle size must be very small (a few tens nanometers) increasing raw material cost
Solution Approach 1:
Instead of adding separate dielectric particles or glass frit as intermediaries, the invention uses a silane coupling agent that forms a molecular-level surface treatment layer on the metal powder. This eliminates the need for additional particulate additives while achieving the same sintering delay effect, significantly reducing material costs.
Solution Approach 2:
The invention changes the approach from adding particulate materials to modifying the surface properties of existing metal powder particles. By controlling the surface treatment parameters with silane coupling agent, sintering delay is achieved without the cost penalty of using ultra-fine dielectric particles.
4Reliability
If surface treatment is applied to Cu powder to improve sintering delay property, then thermal contraction equivalence is achieved, but productivity decreases due to complex treatment steps
Solution Approach 1:
The invention optimizes the surface treatment parameters by using silane coupling agents that can be applied in simple aqueous or alcoholic solutions. The treatment conditions (concentration, temperature, time) are optimized to achieve effective surface modification without requiring complex multi-step processes, thereby maintaining high productivity while improving sintering delay property.
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-treated metal powder paste exhibits improved sintering delay property, high sintering initiation temperature, and excellent dispersibility, preventing delamination and enabling the production of high-quality thin layer electrodes for multilayer ceramic capacitors.
Implementation Method 1
a metal powder and an aqueous solution of an amino group-containing coupling agent are mixed with each other, to allow the amino group-containing coupling agent to be adsorbed on the surface of the metal powder
Implementation Method 2
the metal powder is washed with an aqueous solvent, and thus there can be obtained a metal powder paste free from the aggregation after the surface treatment
Implementation Method 3
in a firing furnace, the internal electrode layers and the dielectric layers are sintered at a high temperature at around 1000°C
Data Source
AI summary
A method for producing a surface-treated metal powder, which comprises: a step for preparing a metal powder dispersion liquid by mixing a metal powder with an aqueous solution of a coupling agent having an amino group; a step for recovering, as a residue, the metal powder from the metal powder dispersion liquid; and a step for cleaning the metal powder, which has been recovered as a residue, with use of an aqueous solvent. This method for producing a surface-treated metal powder provides a method for producing a surface-treated copper powder or metal powder which has excellent sintering delaying properties and is suitable for use in the production of an electrode for multilayer ceramic chip capacitors.