Multilayer Ceramic Electronic Component Electrode Structure

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Solution Overview

Problem

Silver (Ag) migration in multilayer ceramic electronic components leads to short circuit failures, especially at high temperatures, when using Ag as the outermost electrode layer in Pb-free soldering methods, which is a challenge in mounting electronic components without lead (Pb) for reducing environmental impact.

Innovation Solution

The electronic component design includes a structure where the outermost conductive layer contains silver, but it is positioned only on the end surfaces and main surfaces, avoiding contact with the side surfaces, and inner conductors are strategically placed to prevent silver migration, ensuring that the silver layer is not in direct contact with the side surfaces, thereby preventing short circuit failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the outermost electrode layer includes silver to improve affinity with conductive adhesive, then mounting strength is improved, but silver migration occurs at high temperatures causing short circuit failure

Engineering Contradiction:

Improvemounting strengthVSAvoidshort circuit failure

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The outer electrode is divided into multiple functional layers: a base layer (Cu, Ni, or alloy) providing structural support and electrical connection, and a silver-containing outermost layer providing affinity with conductive adhesive. This segmentation allows each layer to perform its specific function without the silver directly contacting the ceramic body, preventing silver migration while maintaining mounting strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base layer acts as an intermediary between the ceramic electronic component body and the silver-containing outermost layer. This intermediate layer prevents direct contact between silver and the ceramic body, blocking the migration path of silver ions while still allowing the silver layer to provide its adhesive affinity function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If silver is used in the outermost electrode layer for Pb-free soldering, then environmental benefits are achieved, but silver migration causes short circuit at high temperatures

Engineering Contradiction:

ImprovePb-free soldering compatibilityVSAvoidshort circuit failure

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The electrode structure is segmented into a base layer and a silver-containing outermost layer, allowing the silver to provide Pb-free soldering compatibility while the base layer prevents silver migration to the ceramic body, thus maintaining reliability at high temperatures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The silver is localized only in the outermost layer where it is needed for adhesive affinity and Pb-free soldering compatibility, while the base layer maintains its non-silver composition to prevent migration. This local quality differentiation solves the contradiction between environmental benefits and reliability.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If the silver layer contacts the side surfaces, then electrode coverage is improved, but silver migration to side surfaces causes short circuit

Engineering Contradiction:

Improveelectrode coverage areaVSAvoidshort circuit failure

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The electrode coverage on side surfaces is achieved through the base layer extending to the side surfaces, while the silver-containing outermost layer is restricted to end surfaces and main surfaces. This segmentation prevents silver contact with side surfaces and subsequent migration, while maintaining adequate electrode coverage through the base layer.

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

This design effectively prevents silver migration and subsequent short circuit failures, facilitating reliable mounting of electronic components using conductive adhesive, even at high temperatures, while maintaining the environmental benefits of Pb-free soldering.

Implementation Method 1

The second conductive layer is deposited on the first conductive layer so as to be positioned at an outermost layer and includes silver

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS7944128B2Electronic component

Publication Date: 2011.05.17 MURATA MFG CO LTD

AI summary

An electronic component includes an electronic component body, first and second outer electrodes, and first and second inner electrodes. The first outer electrode includes a first conductive layer that does not include silver and a second conductive layer that is deposited on the first conductive layer so as to be positioned at an outermost layer and that includes silver. The second conductive layer includes a first contact portion in contact with a first main surface and is not in contact with first and second side surfaces. A first inner conductor is provided on a virtual straight or substantially straight line connecting a second inner electrode closest to the first contact portion and the first contact portion in the shortest distance. The first inner conductor is connected only to the first outer electrode or is connected to none of the first and second outer electrodes.