MLCC Side Margin Layers With Graded Silicon Content
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving sufficient strength and insulation properties due to weak side margin portions, which are prone to cracking and water ingress when dimensions are reduced for smaller sizes.
Innovation Solution
The capacitors incorporate side margin layers with varying silicon content, where the layer closest to the internal electrode has a lower silicon content than others, and a silicon to titanium mole ratio of 1.0 to 7.0, along with a dimension of 5 μm to 40 μm, to enhance strength and prevent cracking and water ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of side margin portions is reduced to achieve higher capacitance in smaller size, then the capacitance density is improved, but the deflecting strength of side margin portions becomes insufficient
Solution Approach 1:
The patent applies local quality by creating side margin portions with non-uniform silicon content distribution. The side margin portions adjacent to internal electrodes have lower silicon content (1-5 mass%) while other side margin portions have higher silicon content (3-7 mass%). This localized variation in material composition provides different mechanical properties in different regions, allowing the structure to maintain sufficient strength at reduced thickness while achieving high capacitance density.
2Productivity
If the thickness of side margin portions is reduced, then the capacitance efficiency is improved, but the side margin portions become more prone to cracking and chipping
Solution Approach 1:
The patent implements local quality by varying the silicon content in different regions of the side margin portions. The region adjacent to internal electrodes contains less silicon (1-5 mass%) for better adhesion and flexibility, reducing stress concentration and crack propagation. Other regions contain more silicon (3-7 mass%) for enhanced mechanical strength and chip resistance, thereby improving overall reliability while maintaining thin dimensions.
3Productivity
If the side margin portions are made thinner, then the electrostatic capacitance is increased, but the insulation properties deteriorate due to water ingress
Solution Approach 1:
The patent applies local quality by creating a gradient in silicon content within the side margin portions. The lower silicon content region (1-5 mass%) near internal electrodes provides better adhesion and flexibility, preventing delamination and reducing pathways for water ingress. The higher silicon content region (3-7 mass%) in other areas provides enhanced mechanical strength and better insulation properties, creating a multi-functional structure that maintains insulation performance even at reduced thickness.
Data Source
AI summary
A multilayer ceramic capacitor includes a laminated body and first and second external electrodes respectively on both end surfaces of the laminated body. When regions where first internal electrodes or second internal electrodes are not present are regarded as side margin portions in a cross section of the laminated body as viewed from the laminating direction, the side margin portions include multiple side margin layers, and the content of Si in the side margin layer closest to the internal electrode is lower than that in the side margin layer other than the side margin layer closest to the internal electrode.