Ceramic Electronic Component Electrode Stress Management

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Solution Overview

Problem

Ceramic electronic components face cracking issues due to residual stress and external stress concentrations, particularly in harsh environments like mobile devices and in-car devices, where thermal cycles and impacts generate deflection stress, leading to potential crack generation and failure.

Innovation Solution

A ceramic electronic component design featuring a laminated body with alternately stacked ceramic and conductor layers, external electrodes with sintered metal, conductive resin, and plated layers, where the sintered metal layers on the principal surfaces are shorter than on the side surfaces, and a lipophobic film is applied to control stress distribution and prevent crack propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sintered metal layer is extended to cover the entire principal surface to increase electrical connection area, then the electrical conductivity is improved, but the residual stress concentration increases causing crack generation

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidresistance to crack generation

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The sintered metal layer is designed with non-uniform distribution: it extends along the side surfaces for electrical connection but is intentionally restricted in length on the principal surfaces to avoid stress concentration. This local differentiation allows the structure to have different properties in different regions - electrical conductivity where needed and stress reduction where critical

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The sintered metal layer exhibits asymmetric geometry relative to the laminated body, with different extension lengths on principal surfaces versus side surfaces. This asymmetric configuration optimizes both electrical connection (along sides) and stress management (restricted on principals), resolving the contradiction between connectivity and structural integrity

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If the external electrode structure is simplified to reduce manufacturing complexity, then the ease of manufacture is improved, but the ability to withstand thermal cycle impacts and dropping forces deteriorates

Engineering Contradiction:

Improveexternal electrode fabrication simplicityVSAvoidresistance to thermal cycle and impact stress

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The external electrode is constructed as a composite structure with multiple layers (sintered metal layer, conductive resin layer, and plated layer) and a lipophobic film, where each material contributes different properties. This composite approach provides both mechanical stress resistance and electrical functionality while maintaining manufacturing feasibility through established processes

Inventive Principle:

Principle #40Composite materials

3Reliability

If the sintered metal layer is made longer to improve electrical connection, then the electrical conductivity is improved, but the residual stress on the laminated body increases leading to crack generation

Engineering Contradiction:

Improveelectrical connection qualityVSAvoidresidual stress concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

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 design effectively reduces residual stress and prevents crack generation by optimizing stress distribution, enhancing the component's durability and reliability in harsh environments.

Implementation Method 1

The sintered metal layer provided on the laminated body

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

the epoxy-based thermosetting resin layer to absorb residual stress generated on the laminated body

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

a plated layer which covers the conductive resin layer

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Data Source

PatentUS10074483B2Ceramic electronic component

Publication Date: 2018.09.11 MURATA MFG CO LTD

AI summary

A ceramic electronic component includes a laminated body including ceramic layers and conductor layers stacked alternately; and first and second external electrodes provided on portions of the laminated body. Each of the first and second external electrodes includes a sintered metal layer provided on the laminated body, a conductive resin layer covering the sintered metal layer, and a plated layer covering the conductive resin layer. The maximum length of the sintered metal layer provided on the second principal surface is shorter than the maximum length of the sintered metal layer provided on each of the first and second side surfaces.