Multilayer Ceramic Capacitor Cover Structure Against Electrode Bending
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multilayer ceramic capacitors face issues with reduced breakdown voltage due to internal electrode bending and delamination between margin portions and the ceramic body, leading to compromised moisture resistance and mechanical strength.
Innovation Solution
The design includes a ceramic body with internal electrodes and dielectric layers, where margin portions are first attached to the capacitance formation portion, and cover portions are then added, featuring distinct cover layers with different physical and chemical properties to prevent delamination and enhance mechanical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of the dielectric layer is formed to be larger than the area of the internal electrode with a margin region, then the internal electrode is protected from direct exposure, but the dielectric layers are stretched to fill step difference portions causing internal electrode bending and reduced breakdown voltage
Solution Approach 1:
The capacitor structure is divided into distinct functional regions: a capacitance formation portion with stacked dielectric layers and internal electrodes, and separate cover portions that extend beyond the capacitance formation portion. This segmentation allows the cover portions to cover the step difference portions without requiring the dielectric layers to be stretched, thereby preventing internal electrode bending while maintaining protective coverage.
2Reliability
If a sheet-shaped margin portion is separately prepared and attached to the ceramic body, then the margin region is provided to protect internal electrodes, but delamination occurs between the margin portion and the ceramic body
Solution Approach 1:
The cover portions are integrated into the ceramic body as a unified structure rather than being separately attached. The cover portions and the capacitance formation portion are formed together in a single sintering process, eliminating the interface between separate components that would be prone to delamination. This merging ensures structural stability and prevents moisture infiltration through delamination gaps.
3Reliability
If multiple dielectric layers are stacked to increase capacity, then the capacitance formation portion is enhanced, but the step difference portions cause mechanical stress and reduced mechanical strength
Solution Approach 1:
The cover portions extend in the horizontal dimension beyond the capacitance formation portion, providing lateral coverage that distributes mechanical stress. This dimensional extension allows the cover portions to absorb external forces applied to the stacked dielectric layers, preventing stress concentration at the step difference portions and maintaining mechanical strength despite multiple layer stacking.
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic body including a dielectric layer, a first internal electrode and a second internal electrode, disposed to oppose each other with the dielectric layer interposed therebetween, and a first external electrode and a second external electrode. The ceramic body further includes first and second margin portions and first and second cover portions, disposed on upper and lower surfaces of a capacitance formation portion and the first and second margin portions, respectively. The first and second cover portions each include a first cover layer adjacent to an internal electrode, disposed on an outermost side among the first and second internal electrodes, and a second cover layer disposed on the first cover layer, and an interface at which the first cover layer and the second cover layer are in contact with each other.