Multilayer Ceramic Capacitor Side Margin Design for Moisture Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving high moisture resistance reliability and withstand voltage due to voids in the side margin portions, which are exacerbated by increased firing temperatures that can lower voltage characteristics in ultra-small and high-capacity products.
Innovation Solution
The solution involves controlling the ratio of the distance between the end points of the side margin portions and the central region of the ceramic body, ensuring it satisfies 1.00 to 1.07, and using a different dielectric material composition for the side margin portions compared to the active portion, with a lower binder content to reduce shrinkage and improve moisture resistance and voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the firing temperature is increased to remove voids in the side margin portion, then moisture resistance reliability is improved, but withstand voltage is lowered due to overfiring of the internal electrode
Solution Approach 1:
The patent applies different dielectric material compositions to different regions of the capacitor. The side margin portion uses a dielectric material with lower binder content (0.5-2.0 wt%) compared to the active portion (1.0-3.0 wt%), allowing localized optimization for void removal without affecting the internal electrode in the active region. This spatial differentiation of material properties enables selective firing behavior in different zones.
Solution Approach 2:
The dielectric material is segmented into two distinct compositions: one for the side margin portion and another for the active portion. This segmentation allows independent optimization of firing characteristics for each region, enabling the side margin to be fired at temperatures that remove voids while keeping the active portion at temperatures that preserve internal electrode integrity and withstand voltage.
2Quantity of substance
If the internal electrode area is increased through marginless design, then capacitance is improved, but voids increase in the side margin portion
Solution Approach 1:
The patent modifies the dielectric material composition specifically in the side margin portion where voids form, using lower binder content to promote better densification and void elimination in this critical region. This local material optimization addresses the reliability issue in the side margin without changing the overall capacitor design that enables high capacitance through increased internal electrode area.
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic body including a dielectric layer, a plurality of first and second internal electrodes disposed inside the ceramic body, exposed to the first and second surfaces, and having ends exposed to the third or fourth surface, and a first side margin portion and a second side margin portion disposed on side portions of the plurality of first and second internal electrodes exposed to the first and second surfaces. A ratio Db/Da satisfies 1.00 to 1.07, inclusive, where ‘Db’ is a distance, in a stacking direction of the dielectric layer, between both end points of respective edge regions of the first side margin portion and the second side margin portion, and ‘Da’ is a distance in a central region of the ceramic body in the stacking direction.