Copper Baked Electrode Structure for Low-ESR Ceramic Components

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Solution Overview

Problem

Conventional ceramic electronic devices face issues with high equivalent series resistance (ESR) due to oxidation of external electrodes at high temperatures and have low mounting strength on substrates.

Innovation Solution

A ceramic electronic device with an external electrode comprising a baked electrode layer made of copper or copper alloy, containing voids, and with the inner wall surfaces of the voids coated with a nickel or nickel alloy film, enhancing electrical conductivity and preventing oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional baked electrode layer is used, then the device structure is simple, but the ESR increases due to oxidation at high temperatures

Engineering Contradiction:

ImproveESR stabilityVSAvoidelectrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrode uses a composite structure with copper particles as the main conductive phase and nickel particles as a protective phase. The copper provides high electrical conductivity while the nickel forms an oxidation-resistant layer on the surface, creating a composite material that simultaneously achieves low ESR and high oxidation resistance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The electrode structure implements local quality differentiation where the inner region consists primarily of copper particles for conductivity, while the outer surface region contains nickel particles for oxidation protection. This spatial distribution of different material properties allows each region to perform its specific function optimally.

Inventive Principle:

Principle #3Local quality

2Reliability

If the baked electrode layer is made denser, then the electrical conductivity improves, but the mounting strength decreases due to increased stress on the element body

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmounting strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The baked electrode layer intentionally incorporates voids with a volume ratio of 5-30% to create a porous structure. This porous design reduces the density and thermal stress of the electrode layer, preventing element body cracking during cooling while maintaining sufficient electrical conductivity through the copper particle network.

Inventive Principle:

Principle #31Porous materials

3Reliability

If copper is used as the main component for high conductivity, then the ESR decreases, but the oxidation resistance worsens at high temperatures

Engineering Contradiction:

Improveelectrical conductivityVSAvoidoxidation resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The nickel particles act as an intermediary protective layer between the copper particles and the oxidizing environment. This nickel layer mediates the interaction between copper and oxygen, preventing direct oxidation of copper while allowing the copper to maintain its high conductivity function.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 device achieves a high mounting strength on substrates and maintains a low ESR, even under high-temperature conditions, due to reduced stress and improved electrical conductivity.

Implementation Method 1

Since the baked electrode layer of the ceramic electronic device according to the present invention includes the void, it is possible to reduce stress applied by the baked electrode layer to the element body in a tightening direction during cooling or the like, after formation of the baked electrode layer on the element body.

Methodology Applied

Scientific EffectStress reduction through void structure:

Implementation Method 2

Nickel and the nickel alloy form a passivation film. Consequently, copper or the like covered by the film, which includes nickel or the like containing the passivation film, is difficult to be oxidized.

Methodology Applied

Scientific EffectPassivation:

Data Source

PatentUS12283430B2Ceramic electronic device having a copper-containing baked electrode layer

Publication Date: 2025.04.22 TDK CORP

AI summary

A ceramic electronic device includes an element body including a ceramic layer and an internal electrode layer, and an external electrode formed on an end surface of the element body and electrically connected to at least one end of the internal electrode layer. The external electrode includes a baked electrode layer. The baked electrode layer includes a main component comprising copper and/or a copper alloy. The baked electrode layer includes a void. An inner wall surface defining the void is at least partly covered by a film comprising nickel and/or a nickel alloy.