Multilayer Ceramic Capacitor Gap Structure Crack Prevention

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Solution Overview

Problem

Multilayer ceramic capacitors face reliability issues due to expansion of inner electrodes during the baking process, leading to cracks in the ceramic element body, which reduces the capacitor's reliability and increases the risk of moisture ingress.

Innovation Solution

Incorporating a gap in the inter-electrode dielectric layer that extends in a direction connecting adjacent inner electrodes, located near the end surfaces of the ceramic element body, to allow for expansion of the inner electrodes while preventing cracks and enhancing moisture resistance through the use of a conductive resin layer on the outer surface of the metal electrode layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conductive paste for forming the metal electrode layers is baked in the manufacturing process, then the outer electrodes are formed and electrically connected to the inner electrodes, but the inner electrodes expand in the stacking direction and width direction, causing cracks to generate from the corner portions of the effective region to the corner portions of the ceramic element body

Engineering Contradiction:

Improvecrack preventionVSAvoidinner electrode dimensional stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a gap structure that segments the ceramic element body into multiple regions. This gap, formed by removing portions of the ceramic green sheet before lamination, creates a relief structure that allows the inner electrodes to expand into the gap space during the baking process without generating cracks in the effective region. The segmentation effectively separates the expansion zone from the capacitance-forming region.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gap is formed in advance during the green sheet preparation stage, before the inner electrodes are stacked and before the baking process occurs. This preliminary action of creating the gap structure ensures that when the inner electrodes expand during baking, there is pre-prepared space for the expansion, preventing crack formation in the effective region where capacitance is generated.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the inner electrodes expand during the baking process, then the outer electrodes can be properly formed, but cracks are generated in the ceramic element body, decreasing reliability

Engineering Contradiction:

Improveouter electrode formationVSAvoidcapacitor reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent converts the harmful effect of inner electrode expansion (which causes cracks) into a beneficial outcome by providing a designated gap space for the expansion to occur. The expansion, which would otherwise be harmful, is redirected into the gap region, thereby protecting the effective region from cracks while still allowing the outer electrodes to be properly formed through the baking process.

Inventive Principle:

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

3Strength

If cracks are generated from the corner portions of the effective region to the corner portions of the ceramic element body, then the structural integrity is compromised, but moisture ingress risk increases, further reducing reliability

Engineering Contradiction:

Improvestructural integrityVSAvoidmoisture ingress

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The gap structure serves as a cushioning zone that absorbs the expansion stress of the inner electrodes before it can propagate into cracks. By providing this stress-absorbing space in advance, the patent prevents the formation of crack pathways that would otherwise allow moisture to ingress into the ceramic element body, thereby protecting both structural integrity and moisture resistance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively restricts the expansion of inner electrodes in the stacking and width directions, preventing cracks and improving the reliability and moisture resistance of the multilayer ceramic capacitors, thereby ensuring high reliability and stability.

Implementation Method 1

when the conductive paste for forming the metal electrode layers 105 is baked in a manufacturing process thereof, the inner electrodes 102 may expand in a stacking direction (thickness direction, height direction, or T direction) of the inner electrodes 102 and a width direction

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9761376B2Multilayer ceramic capacitor

Publication Date: 2017.09.12 MURATA MFG CO LTD

AI summary

In a multilayer ceramic capacitor in which an outer electrode is arranged on a ceramic element body to be electrically connected to an inner electrode, the outer electrode includes a metal electrode layer on the ceramic element body, and a conductive resin layer on the metal electrode layer. When a dielectric layer between a pair of the inner electrodes adjacent in a stacking direction among a plurality of the inner electrodes extending to one of a pair of end surfaces of the ceramic element body is an inter-electrode dielectric layer, a gap extends a direction connecting the adjacent inner electrodes sandwiching the inter-electrode dielectric layer at a position near or adjacent to at least the one of the end surfaces.