Porous External Electrode Structure for Bend-Resistant Multilayer Capacitors

Solution Overview

Problem

Multilayered ceramic capacitors face challenges in achieving stable electrical characteristics and reliability, particularly in withstanding mechanical deformation and high-temperature environments, due to limitations in bending strength and thermal expansion issues.

Innovation Solution

A multilayered capacitor design featuring an external electrode with a low elasticity coefficient, composed of a first conductive metal layer and a second layer with an alloy of a higher conductive metal and a low melting point metal, incorporating a porous structure to reduce stress and thermal expansion, and optionally a plating layer for improved durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional external electrode with high elasticity coefficient is used, then the electrode provides good electrical conductivity, but it applies excessive stress to the multilayered capacitor during mechanical deformation, reducing bending strength

Engineering Contradiction:

Improvebending strengthVSAvoidstress applied to capacitor

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The external electrode incorporates a porous structure with controlled porosity (30-70%) in the second layer, making the material more compliant and flexible. This porous configuration reduces the elasticity coefficient, allowing the electrode to deform without applying excessive stress to the capacitor body, thereby improving bending strength while maintaining electrical conductivity through the conductive metal framework

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The external electrode uses a composite structure with two layers: the first layer contains a conductive metal (Cu, Ni, Ag, Pd, Au, Pt, W, or Ti) for electrical conductivity, while the second layer combines conductive metal with a porous structure. This composite design balances electrical performance with mechanical compliance, reducing stress on the capacitor during deformation

Inventive Principle:

Principle #40Composite materials

2Temperature

If materials with large thermal expansion difference are used in the external electrode, then the electrode can be manufactured with standard materials, but the capacitor exhibits shape change and poor heat resistance at high temperatures

Engineering Contradiction:

Improveheat resistanceVSAvoidshape change due to thermal expansion

Core Design Contradiction:

TemperatureVSShape

Solution Approach 1:

The patent modifies the physical parameters of the external electrode by incorporating a porous structure and selecting specific conductive metals with thermal expansion coefficients matched to the capacitor body. This parameter adjustment reduces thermal stress and prevents shape changes at high temperatures, improving heat resistance while allowing standard manufacturing materials

Inventive Principle:

Principle #35Parameter changes

3Strength

If the external electrode uses a dense structure without pores, then the electrode maintains low electrical resistance, but it has high elasticity coefficient and poor bending strength

Engineering Contradiction:

Improvebending strengthVSAvoidelectrical stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The external electrode incorporates a porous structure with controlled porosity (30-70%) in the second layer, making the material more compliant and flexible. This porous configuration reduces the elasticity coefficient, allowing the electrode to deform without applying excessive stress to the capacitor body, thereby improving bending strength while maintaining electrical conductivity through the conductive metal framework

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The external electrode uses a composite structure with two layers: the first layer contains a conductive metal (Cu, Ni, Ag, Pd, Au, Pt, W, or Ti) for electrical conductivity, while the second layer combines conductive metal with a porous structure. This composite design balances electrical performance with mechanical compliance, reducing stress on the capacitor during deformation

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 enhances bending strength, maintains low equivalent series resistance, and exhibits excellent heat resistance by minimizing thermal expansion and material decomposition at high temperatures.

Implementation Method 1

an external electrode having a low elasticity coefficient to reduce a stress applied to the multilayered capacitor due to external mechanical deformation

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a second layer disposed on the first layer and including an alloy of a second conductive metal and a low melting point metal having a melting point lower than that of the second conductive metal

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentEP4421835A1Multilayered capacitor and method for manufacturing the same

Publication Date: 2024.08.28 SAMSUNG ELECTRO MECHANICS CO LTD

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AI summary

A multilayered capacitor includes a capacitor body in which dielectric layers and internal electrodes are stacked in a first direction, and an external electrode disposed on the capacitor body. The external electrode includes a first layer including a first conductive metal, and a second layer disposed on the first layer and including an alloy of a second conductive metal and a low melting point metal having a melting point lower than that of the second conductive metal and having a plurality of pores, and an area ratio of pores in a unit area of the second layer to a unit area of the second layer is greater than or equal to about 30%.