MLCC External Electrode Layout for Bending Crack Resistance

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Solution Overview

Problem

Multilayer ceramic capacitors with thin outer and side margin portions are prone to cracking and short circuits when bent, due to stress concentration on convex portions of the external electrodes, which can lead to moisture infiltration and defects.

Innovation Solution

Designing multilayer ceramic capacitors with external electrodes that have longest portions on the side margin portions, rather than the center, and incorporating silicon-rich side margin portions for enhanced mechanical strength and adhesion, to prevent crack propagation to internal electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the multilayer ceramic capacitor is reduced in size with very thin outer layer portions and side margin portions, then the capacitance can be increased, but the capacitor becomes prone to bending and cracking when subjected to bending forces

Engineering Contradiction:

ImprovecapacitanceVSAvoidresistance to bending

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The external electrode is designed with non-uniform thickness, featuring a thick portion at the center in the width direction and thin portions at both ends in the width direction. This local variation in thickness distributes stress away from the center during bending, preventing crack initiation at the thickest point while maintaining overall structural integrity and capacitance.

Inventive Principle:

Principle #3Local quality

2Reliability

If the external electrode has a convex shape with the longest length at the center portion, then the electrode provides good electrical connection, but stress concentrates on the convex portion causing cracks in the thin outer layer

Engineering Contradiction:

Improveelectrical connectionVSAvoidstress concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The external electrode features a convex portion at the center with the longest length providing optimal electrical connection, while the ends have shorter lengths that reduce stress concentration during bending. This local differentiation allows the center to maintain reliability while the ends avoid crack initiation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The convex shape of the external electrode, which initially appears to cause stress concentration, is designed such that the thick center portion absorbs stress while the thin portions at the ends prevent crack propagation. The harmful stress concentration is converted into a beneficial stress distribution pattern.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20240395462A1Multilayer ceramic capacitor and method of mounting multilayer ceramic capacitor

Publication Date: 2024.11.28 MURATA MFG CO LTD

AI summary

A multilayer ceramic capacitor includes a multilayer body including dielectric layers and internal electrode layers alternately laminated, main surfaces, side surfaces, and end surfaces, and external electrodes on the end surfaces and each including an end surface portion on the end surface where the external electrode is provided, main surface portions respectively extending on the main surfaces between the end surfaces, and side surface portions respectively extending on the side surfaces between the end surfaces. Each main surface portion includes a longest portion longer than a remainder of the main surface portion. When the multilayer ceramic capacitor is viewed from the main surface, the longest portion is located on a region that does not overlap with a region in which the internal electrode layers are located.