Multilayer Ceramic Capacitor Al-Si Oxide Defects
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Solution Overview
Problem
Multilayer ceramic capacitors with reduced dielectric and internal electrode layers thickness and increased number face challenges in maintaining reliability under high electric fields in hot and humid conditions due to moisture ingress and barium titanate component elution.
Innovation Solution
Incorporating Al—Si based oxide defects in internal electrode layers, with a 30% or more ratio, and optimizing the content of Al, Si, rare-earth elements, Mg, Mn, V, and Zr to suppress moisture ingress and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dielectric layers and internal electrode layers are reduced in thickness and increased in number, then capacitance increases and size reduces, but electrode defects increase due to deformations and shrinkage differences
Solution Approach 1:
The patent applies parameter changes by controlling the thickness of internal electrode layers to 0.6 μm or less and adjusting the composition ratio of Al-Si based oxide to 30% or more of total electrode defects. These parameter modifications optimize the balance between achieving high capacitance density through thin layers and maintaining sufficient electrode coverage despite manufacturing variations.
2Manufacturing precision
If vacancies are formed in internal electrode layers to reduce defects, then electrode uniformity improves, but moisture ingress occurs from outside to interfaces
Solution Approach 1:
The patent converts the harmful effect of vacancies into a beneficial one by filling them with Al-Si based oxide. The oxide fills the vacancies that would otherwise allow moisture ingress, transforming the defect into a protective feature that maintains electrode uniformity while preventing moisture penetration.
Solution Approach 2:
The Al-Si based oxide acts as an intermediary substance that fills the vacancies in internal electrode layers. This intermediate material prevents direct contact between moisture and the electrode-defect interface, blocking the harmful moisture ingress pathway while maintaining structural integrity.
3Reliability
If barium titanate is used as main constituent for high dielectric constant, then capacitance increases, but barium component elution occurs in hot and humid conditions
Solution Approach 1:
The patent employs composite materials by combining barium titanate with Al-Si based oxide in the internal electrode layers. This composite structure maintains the high dielectric constant benefits of barium titanate while the Al-Si oxide component prevents barium elution in hot and humid conditions, ensuring long-term reliability.
Data Source
AI summary
A multilayer ceramic capacitor that has alternately stacked dielectric layers containing, as their main constituent, a barium titanate based compound that has a perovskite-type crystal structure; and internal electrode layers with electrode defects. The internal electrode layers are 0.6 μm or less in thickness. The electrode defects have electrode defects containing an Al—Si based oxide mainly containing Al and Si. The number of the electrode defects containing the Al—Si based oxide is 30% or more in number ratio to the total number of electrode defects in the internal electrodes.