Laminated Ceramic Capacitor Grain Size Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laminated ceramic capacitors using CaZrO3-based dielectric ceramic materials experience peeling defects due to stress differences between internal electrodes and dielectric ceramic, and increased grain size in outer layers leads to moisture-resistance issues, while reducing grain size compromises sinterability and dielectric constant.
Innovation Solution
A laminated ceramic capacitor design with a perovskite-type compound containing Ca, Zr, Si, and Mn, where the average grain size in the outer layer sections is smaller than in the inner sections, and a controlled Si/Mn molar ratio near interfaces, stabilizes interfacial bonding and improves moisture resistance without compromising sinterability or dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the average grain size in outer layer sections is reduced to improve moisture resistance, then moisture resistance is improved, but sinterability deteriorates
Solution Approach 1:
The patent applies different grain size controls to different regions: outer layer sections have smaller average grain size (≤10 μm) for moisture resistance, while inner layer sections can have larger grain size for good sinterability. This spatial differentiation of material properties resolves the contradiction between moisture resistance and sinterability.
Solution Approach 2:
The patent changes the chemical composition parameters by adding specific amounts of Si (0.01-5 wt%) and Mn (0.01-5 wt%) to the dielectric ceramic. These compositional changes enable grain growth inhibition during sintering, allowing small grain size in outer layers while maintaining overall sinterability through controlled densification.
2Reliability
If the average grain size in outer layer sections is reduced to improve moisture resistance, then moisture resistance is improved, but dielectric constant deteriorates
Solution Approach 1:
The patent creates functional differentiation between outer and inner layers: outer layers have small grain size optimized for moisture resistance, while inner layers maintain larger grain size for high dielectric constant. The stacked structure allows each region to optimize its properties independently, resolving the contradiction between moisture resistance and dielectric performance.
Solution Approach 2:
The patent uses a composite dielectric ceramic system containing Ca, Zr, Si, and Mn elements. The Si and Mn form secondary phases at grain boundaries that pin grain growth in outer layers while the bulk material maintains high dielectric properties through the perovskite structure, achieving both small grain size and high dielectric constant.
3Quantity of substance
If CaZrO3-based dielectric ceramic is used to achieve specific electrical properties, then electrical performance is improved, but peeling defects increase due to stress differences
Solution Approach 1:
The patent modifies the dielectric ceramic composition by adding Si and Mn elements to the CaZrO3-based system. This compositional change adjusts the linear expansion coefficient to be closer to that of internal electrodes, reducing thermal stress and preventing peeling defects while maintaining the electrical performance of the perovskite structure.
Solution Approach 2:
The Si and Mn elements act as intermediaries that mediate between the dielectric ceramic and internal electrodes. They form interfacial phases that reduce the expansion coefficient mismatch and improve bonding, resolving the peeling issue while preserving the electrical properties of the CaZrO3-based dielectric.
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 design enhances moisture resistance and chemical stability, reducing peeling defects and residual stress, while maintaining high sinterability and dielectric performance.
Implementation Method 1
the average grain size of the dielectric ceramic constituting the outer layer section is smaller than the average grain size of the dielectric ceramic constituting the inner layer section
Implementation Method 2
the dielectric ceramic layers constituting the inner layer section and the outer layer section contain a perovskite-type compound containing Ca and Zr
Implementation Method 3
the Si/Mn molar ratio in the dielectric ceramic near the interfaces between the internal electrodes and the dielectric ceramic layers (generally about 5 nm or less) is ≦15
Implementation Method 4
stabilizes interfacial bonding and improves moisture resistance without compromising sinterability or dielectric constant
Implementation Method 5
When the average grain size is increased in the outer layer sections, peeling defects between the grains are likely to occur in a moisture-resistance loading test and the like. The defects in the moisture-resistance loading test are believed to be caused by ingress of a plating solution or moisture through erosion of defective external electrodes and ceramic grain boundaries
Implementation Method 6
Then, the green chip is subjected to firing to form a chip sintered body
Data Source
AI summary
laminated ceramic capacitor which has favorable moisture resistance includes an inner layer section that has dielectric ceramic layers and internal electrodes stacked alternately, and outer layer sections formed outside the inner layer section. The dielectric ceramic layers have a perovskite-type compound including a main constituent containing Ca and Zr, and an additive containing Si and Mn. The average grain size in the dielectric ceramic layers constituting the outer layer sections is smaller than the average grain size in the dielectric ceramic layers constituting the inner layer section. The Si/Mn molar ratio in the dielectric ceramic near the interfaces between the internal electrodes and the dielectric ceramic layers is ≦15.