Surface-Treated Copper Powder for MLCC Electrodes
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Solution Overview
Problem
Current methods for producing copper powders for internal electrodes in chip laminated ceramic capacitors face challenges such as low sintering initiation temperature, electrode delamination, and difficulty in achieving thin layers due to the low melting point of copper and increased surface area of small particles, which affects the sintering delay property and operability.
Innovation Solution
Surface-treated copper powders with specific nitrogen content and deposition amounts of elements like Si or Ti, using amino group-containing coupling agents, are developed to enhance the sintering initiation temperature and prevent aggregation, allowing for the production of electrodes with improved sintering delay property and flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu powder is used for internal electrodes to reduce cost and achieve low inductance, then cost and inductance are improved, but sintering initiation temperature decreases causing electrode cracks and delamination
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance that forms a surface treatment layer on Cu powder particles. This layer acts as a mediator that delays sintering initiation while maintaining electrical conductivity, preventing direct Cu-Cu contact that would cause premature sintering and electrode defects
Solution Approach 2:
The surface treatment changes the physical and chemical parameters of Cu powder by forming a silane-based coating layer. This modifies the surface energy and thermal properties, raising the sintering initiation temperature from typical Cu values to above 800°C, matching the dielectric's thermal contraction behavior
2Length of moving object
If particle size of Cu powder is reduced to achieve thinner electrode layers, then electrode thickness is improved, but surface area increases causing earlier melting and sintering issues
Solution Approach 1:
The silane coupling agent forms a protective intermediary layer on the surface of fine Cu powder particles (0.5-5 μm). This layer prevents direct particle-to-particle contact and heat transfer, allowing fine particles to be used without premature sintering, thus enabling thin electrode layer formation
Solution Approach 2:
The invention creates a composite structure where Cu powder particles are coated with a silane-based surface treatment layer. This composite material combines the electrical conductivity of Cu with the thermal stability of the silane layer, enabling use of fine particles for thin electrodes
3Temperature
If amino group-containing coupling agent is used for surface treatment, then sintering delay property is improved, but production complexity increases
Solution Approach 1:
The invention optimizes the surface treatment parameters by controlling the amino group content (0.01-10 wt%) and silane concentration in the aqueous solution. This parameter control achieves effective sintering delay (Ts > 800°C) while maintaining a relatively simple production process suitable for industrial scale-up
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 copper powders exhibit a higher sintering initiation temperature and prevent electrode delamination, enabling the production of high-quality, thin-layer electrodes for multilayer ceramic capacitors with improved operability and productivity.
Implementation Method 1
a step of surface-treating a metal powder with an amino group-containing coupling agent
Implementation Method 2
a step of collecting the metal powder as a residue from the metal powder dispersion liquid
Data Source
Figure 1
AI summary
Provided are a surface-treated copper powder and a metal powder that exhibit superior sinter delay properties and are suitable for use in the manufacture of electrodes for multilayer ceramic capacitor chips. The surface-treated metal powder has an N (nitrogen) content of at least 0.02 wt% relative to the surface-treated metal powder, and satisfies the formulas 50 ≤ x ≤1500 and y ≥ 0.2x + 600, in which x is the coating mass per 1 g of metal powder of one element selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn, and in which y (ºC) is the starting temperature of sintering. Also provided is a method for producing the powders.