Nickel Oxide Coated Paste for MLCC Internal Electrodes
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving subminiaturized size and high capacitance due to particle growth and disconnection of internal electrodes, leading to structural defects and reduced capacitance, as nickel powder sintering initiates at a lower temperature than ceramic sheets, causing stress and delamination.
Innovation Solution
A conductive paste for internal electrodes comprising nickel powder, nickel oxide powder with a content of 5.0 to 15.0 parts by weight, and an organic vehicle, including an ethyl cellulose-based binder and terpineol, is used to form internal electrodes with a shrinkage initiation temperature higher than the ceramic body, ensuring proper sintering and connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel powder is used for internal electrodes with high surface area and activity, then the sintering initiation temperature is significantly low, but this causes the internal electrode to sinter and shrink at a lower temperature than the ceramic sheet, generating stress and structural defects
Solution Approach 1:
An oxide coating layer is introduced as an intermediary substance between the nickel powder particles and the environment. This coating layer acts as a barrier that prevents direct oxidation and controls the sintering process, raising the sintering initiation temperature to match the ceramic sheet sintering temperature, thereby preventing stress and structural defects
Solution Approach 2:
The surface properties of nickel powder are modified by coating with oxide, which changes the sintering initiation temperature from a low value to a higher value that matches the ceramic sheet sintering temperature. This parameter change ensures synchronized sintering and prevents stress generation
2Temperature
If nickel powder particles are coated with oxide to raise sintering temperature, then the sintering initiation temperature increases, but the oxide may react with the ceramic of the dielectric layer to change ceramic characteristics
Solution Approach 1:
The oxide coating is applied locally and specifically to the nickel powder particles rather than the entire assembly. This localized treatment raises the sintering temperature of the nickel without exposing the ceramic dielectric layer to oxidative conditions that would change its characteristics, thus resolving the contradiction between temperature control and material stability
3Temperature
If a coating layer is formed around agglomerated nickel particles, then shrinkage is initiated at low temperature destroying the coating layer, but this causes the sintering process to progress rapidly and extrude oxide to the outside
Solution Approach 1:
The oxide coating transforms the sintering initiation temperature from low to high, ensuring that shrinkage occurs at temperatures that preserve the coating integrity rather than destroying it. This parameter change prevents the rapid sintering and oxide extrusion that would compromise reliability
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 solution effectively delays the sintering initiation of internal electrodes, preventing delamination and cracking, while maintaining high capacitance and reliability by ensuring the internal electrodes and ceramic body sinter at compatible temperatures, thus improving the manufacturing process and product quality.
Implementation Method 1
a shrinkage initiation temperature higher than the ceramic body, ensuring proper sintering and connectivity
Data Source
AI summary
There are provided a conductive paste for internal electrodes, a multilayer ceramic electronic component including the same, and a method of manufacturing the same. The conductive paste for internal electrodes including: a nickel (Ni) powder; a nickel oxide (NiO) powder having a content of 5.0 to 15.0 parts by weight based on 100 parts by weight of the nickel powder; and an organic vehicle.