MLCC External Electrode Recess Structure for Crack Prevention
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Solution Overview
Problem
Multi-layer ceramic capacitors face defects such as cracks due to thermal stress between electrode materials and ceramic bodies with different linear expansion coefficients, leading to reliability issues and insulation failures.
Innovation Solution
A multi-layer ceramic electronic component design featuring a ceramic body with a protective portion including a recess and outer edge, and an external electrode with a base film covering the end surface, circumferential surfaces, and recess, where the second covering portions on the circumferential surfaces are spaced apart from the third covering portion on the recess, minimizing stress accumulation and ensuring continuous plating film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first to fifth portions of the fired electrode layer are separated to prevent cracks, then crack prevention is improved, but the width control becomes difficult and Cu plating films separate leading to insulation failure
Solution Approach 1:
The patent changes the geometric parameters of the electrode layer by introducing a recess with specific dimensions (depth of 1-5 μm, width of 1-5 μm) and controlling the separation width (1-5 μm) between portions. These parameter specifications allow the electrode to prevent cracks while maintaining sufficient width for continuous Cu plating film formation, thus resolving the contradiction between crack prevention and manufacturing precision.
2Reliability
If the base film covers all surfaces continuously to ensure plating film continuity, then insulation reliability is improved, but stress accumulation increases due to different linear expansion coefficients
Solution Approach 1:
The patent segments the base film coverage by creating a recess that causes the second covering portions on circumferential surfaces to be spaced apart from the third covering portion on the recess. This segmentation reduces stress accumulation by allowing differential expansion while the plating film continuously covers all portions including the recess, maintaining insulation reliability.
3Reliability
If the separation width between electrode portions is reduced to maintain plating film continuity, then insulation failure is prevented, but stress concentration increases at the narrow gaps
Solution Approach 1:
The patent optimizes the separation width parameter to a specific range (1-5 μm) that is sufficient to reduce stress concentration compared to larger separations, yet small enough to allow continuous Cu plating film formation. The recess depth (1-5 μm) and width (1-5 μm) are also controlled to ensure the plating film can bridge the gap while minimizing stress concentration at the narrow regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively prevents stress-induced defects in the ceramic body and external electrodes, enhancing the reliability of the multi-layer ceramic capacitors by minimizing stress accumulation and maintaining a continuous plating film, thus preventing breakage and insulation failures.
Implementation Method 1
The base film containing an electrode material and the ceramic body have different linear expansion coefficients, and thus the second covering portions are subjected to stress in different directions by heating and cooling.
Data Source
AI summary
A multi-layer ceramic electronic component includes (I) a ceramic body including (i) a protective portion that includes an end surface facing in a first direction, circumferential surfaces, and a ridge including a recess extending along the first direction and connects the circumferential surfaces, and (ii) a functional portion including internal electrodes laminated in a second direction, and (II) an external electrode including (i) a base film covering the end surface and including a first, second, and third covering portions formed on the end surface, on the circumferential surfaces, and on the recess, respectively, (ii) an intermediate film formed on the base film and continuously covering the first, second, and third covering portions, and (iii) a surface film formed on the intermediate film, wherein the recess is disposed outside end portions of the internal electrodes in a third direction orthogonal to the first and second directions.