MLCC Internal Electrode Layout for Electrostrictive Crack Reduction

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Solution Overview

Problem

Multilayer ceramic capacitors (MLCCs) face electrostrictive cracks due to physical expansion forces exceeding the yield strength of the dielectric material, leading to damage, particularly at the boundary regions between the active and margin portions.

Innovation Solution

The MLCC design includes offset internal electrodes with specific configurations and lengths to create an electrical field reduction region, reducing the sudden difference in electrical field density between the active and margin portions, thereby minimizing electrostrictive stress and crack formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If internal electrodes are disposed adjacent to the margin portions (fifth and sixth surfaces), then the capacitance is increased, but electrostrictive cracks occur due to sudden electrical field density difference

Engineering Contradiction:

ImprovecapacitanceVSAvoidcrack resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the configuration of internal electrodes in different regions. In the active region, internal electrodes are disposed to maximize capacitance, while in the margin portions, internal electrodes are offset or reduced in number to create an electrical field reduction region. This local differentiation allows the capacitor to maintain high capacitance in the active area while preventing electrostrictive cracks at the margins where the electrical field gradient would otherwise be too steep.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If internal electrodes are disposed to maximize capacitance in active region, then the electrical field density increases, but the gradient between active and margin portions causes stress concentration

Engineering Contradiction:

ImprovecapacitanceVSAvoidelectrostrictive stress

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The patent introduces an intermediary electrical field reduction region in the margin portions, created by offsetting or reducing internal electrodes. This intermediary region acts as a buffer zone that gradually transitions the electrical field density from the high-density active region to the low-density margin portions, preventing sudden changes that would cause stress concentration and electrostrictive cracks.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If internal electrodes are offset in the margin portions, then the electrical field gradient is reduced, but the manufacturing complexity increases

Engineering Contradiction:

Improvecrack resistanceVSAvoidelectrode configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the capacitor body into distinct regions: an active region with full internal electrode configuration for maximum capacitance, and margin portions with offset or reduced internal electrodes to create electrical field reduction zones. This segmentation allows each region to be optimized independently - the active region for capacitance and the margin regions for stress reduction - while maintaining a systematic manufacturing approach.

Inventive Principle:

Principle #1Segmentation

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

The offset internal electrode configuration effectively reduces electrostrictive cracks by mitigating the electrical field gradient, enhancing the structural integrity of the capacitor body and reducing the likelihood of chip breakage.

Implementation Method 1

Methodology Applied

Scientific EffectElectrical field gradient reduction: Electric Field

Implementation Method 2

Physical expansion force caused by the electrostrictive phenomenon may be transmitted to a capacitor body such that the force may exceed yield strength of a dielectric in severe cases

Methodology Applied

Scientific EffectElectrostriction: Electrostriction

Data Source

PatentUS11837407B2Multilayer capacitor and board having the same mounted thereon

Publication Date: 2023.12.05 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

A multilayer capacitor includes a capacitor body including first to sixth surfaces, dielectric layers and first and second internal electrodes alternately disposed with the dielectric layer interposed therebetween in a first direction; and first and second external electrodes; wherein the first and second internal electrodes are disposed to be offset in the first direction, wherein a first plurality of the first and second internal electrodes is disposed to be adjacent to the fifth surface in the third direction, a second plurality is disposed to be adjacent to the sixth surface in the third direction, and a third plurality is disposed in a central region in the third direction, and wherein internal electrodes among the first and second internal electrodes, disposed to be adjacent to the surface in the same direction, include an even number of two or more of internal electrodes disposed to be offset therebetween.