MLCC External Electrode Profile for Corner Moisture Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayer ceramic capacitors face issues with uniform external electrode thickness, leading to degraded corner coverage performance and moisture resistance reliability due to thin outer electrode formation, which allows penetration of external substances like moisture.
Innovation Solution
The design features external electrodes with a central portion and an outer portion, where the outer portion is thicker than the central portion, and the boundary region between them is concave, ensuring improved corner coverage and enhanced moisture resistance by using a conductive metal and glass composition that increases density and suppresses penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external electrodes are formed by the dipping method, then the external electrodes can be formed on the ceramic body, but the external electrodes have non-uniform thickness with thinner outer portions
Solution Approach 1:
The external electrode is designed with different thicknesses in different regions: the outer portion has a first thickness while the center portion has a second thickness greater than the first thickness. This local quality variation ensures that the outer portion provides adequate coverage and moisture resistance, while the center portion maintains sufficient conductivity and mechanical strength.
2Ease of manufacture
If external electrodes are formed thin at the outer portion, then the dipping process is simpler, but corner coverage performance is degraded
Solution Approach 1:
The external electrode structure implements local quality by having the outer portion with first thickness providing corner coverage, while the center portion with greater second thickness provides electrical connectivity. This resolves the contradiction by ensuring adequate thickness at the outer portion for reliable corner coverage while maintaining manufacturing simplicity.
3Volume of moving object
If external electrodes are formed thin, then the overall capacitor size can be reduced, but moisture resistance reliability deteriorates due to penetration of external substances
Solution Approach 1:
The external electrode is designed with the outer portion having first thickness and the center portion having greater second thickness. This local quality differentiation ensures that the outer portion provides sufficient barrier thickness for moisture resistance at the corners, while the overall electrode remains compact, thus resolving the contradiction between size reduction and moisture resistance.
4Reliability
If the external electrode thickness is increased uniformly, then moisture resistance is improved, but the capacitor becomes larger
Solution Approach 1:
The external electrode structure implements local quality by having the outer portion with first thickness and the center portion with greater second thickness. This ensures that moisture resistance is improved at the outer portion where it is most needed for corner coverage, while the center portion maintains appropriate thickness for electrical function without excessive overall size increase.
Data Source
AI summary
A multilayer ceramic capacitor includes a body including a dielectric layer and first and second internal electrodes stacked in a first direction and having first and second surfaces opposing each other in the first direction, third and fourth surfaces opposing each other in a second direction, and fifth and sixth surfaces opposing each other in a third direction, and first and second external electrodes disposed on the third and fourth surfaces of the body, respectively, and connected to the first and second internal electrodes, respectively. The first and second external electrodes each include a central portion disposed in a center of each of the third and fourth surfaces and an outer portion disposed outside the central portion. T1>T2>T3, in which T1 and T3 are maximum value and minimum value of a thickness of the central portion, respectively, and T2 is a maximum value of a thickness of the outer portion.