Multilayer Ceramic Capacitor Electrode Structure for Stress Dispersion
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Solution Overview
Problem
Existing multilayer ceramic capacitors face issues with cracks extending from the tip of the external electrode to the interior due to thick electrode thickness and covered end portions, which are exacerbated by reduced height demands in modern electronic equipment.
Innovation Solution
The multilayer ceramic capacitor design includes a specific configuration of external electrodes with varying lengths and orientations to disperse stress, using a base electrode layer and plated layer with distinct main surface electrode portions, ensuring a relationship of A>B>C>D, which enhances stress dispersion and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the external electrode is made thick to ensure mechanical strength, then the electrode can provide sufficient structural support, but cracks may extend from the tip of the external electrode to the interior of the multilayer ceramic capacitor
Solution Approach 1:
The external electrode is divided into multiple distinct portions (first main surface electrode portion, second main surface electrode portion, third main surface electrode portion, and fourth main surface electrode portion) with different lengths in the lamination direction. This segmentation allows stress to be distributed across multiple locations rather than concentrated in a single thick electrode structure, preventing crack propagation from the electrode tip into the capacitor interior while maintaining sufficient mechanical strength.
2Length of moving object
If the height of the multilayer ceramic capacitor is reduced to meet miniaturization demands, then the capacitor can be used in compact electronic equipment, but the external electrode thickness may increase relative to the overall height, increasing crack risk
Solution Approach 1:
By segmenting the external electrode into multiple portions with progressively shorter lengths (first portion longest, fourth portion shortest), the design accommodates reduced overall height while distributing stress across different heights. This prevents the relative thickness increase that would otherwise occur in miniaturized capacitors, maintaining crack resistance even as overall height decreases.
Solution Approach 2:
The electrode structure extends in multiple dimensions with portions having different lengths in the lamination direction, creating a stepped configuration. This dimensional variation allows the electrode to maintain adequate stress distribution capabilities even when the overall capacitor height is reduced, as the stress is managed through the multi-level structure rather than through increased thickness in a single dimension.
3Reliability
If the end portions of the films are covered to protect the interior, then the capacitor interior is shielded, but stress concentration may occur leading to crack extension
Solution Approach 1:
The external electrode is segmented into portions of different lengths, where the first main surface electrode portion extends furthest and subsequent portions are progressively shorter. This segmentation ensures that no single covered end portion creates a stress concentration point, as the stress is distributed across multiple electrode portions with varying lengths, preventing crack initiation while still providing protection to the capacitor interior.
Data Source
AI summary
In a multilayer ceramic capacitor, first and second external electrodes respectively include first main surface electrode portions, second main surface electrode portions, third main surface electrode portions, and fourth main surface electrode portions, on a first main surface. When a length of the first main surface electrode portions, is denoted by length A, a length of the second main surface electrode portions, is denoted by length B, a length of the third main surface electrode portions, is denoted by length C, and a length of the fourth main surface electrode portions is denoted by length D, a relationship of length A>length B>length C>length D is satisfied.