Multilayer Ceramic Electrode Alloying to Suppress Ni Diffusion

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Solution Overview

Problem

The reliability and lifetime characteristics of ceramic electronic devices, particularly multilayer ceramic capacitors, are compromised due to oxygen vacancies generated in dielectric layers when nickel (Ni) is used as internal electrodes in a reductive firing atmosphere, leading to reduced durability and variability in device lifespan.

Innovation Solution

Incorporating tin (Sn) and gold (Au) into the internal electrode layers, which form an alloy with Ni, thereby altering the interface conditions and suppressing Ni diffusion into the dielectric layers, thus enhancing the durability and consistency of the ceramic electronic device's lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Ni is used as internal electrode layers in a reductive firing atmosphere, then oxidation of Ni is prevented, but oxygen vacancies are generated in dielectric layers leading to degraded reliability

Engineering Contradiction:

Improvedevice reliabilityVSAvoidoxygen vacancies in dielectric layers

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a protective coating layer comprising SiO2, SiNx, or SiOxNy as an intermediary between the Ni internal electrode and the dielectric layer. This coating prevents direct interaction between Ni and the dielectric during reductive firing, allowing the use of reductive atmosphere to maintain Ni while preventing oxygen vacancy generation in the dielectric layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite material structures by combining Ni with protective coating materials (SiO2, SiNx, or SiOxNy) to create a multi-layer internal electrode structure. This composite approach enables simultaneous achievement of oxidation resistance from Ni and protection against oxygen vacancy generation through the coating layer.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If reductive atmosphere is used in the firing process, then Ni oxidation is prevented, but oxygen vacancies are generated in dielectric layers

Engineering Contradiction:

ImproveNi composition stabilityVSAvoidoxygen vacancies

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The protective coating layer acts as a mediator that allows the reductive firing atmosphere to maintain Ni composition stability while preventing the generation of oxygen vacancies in the dielectric layer by blocking the harmful effects of the reductive atmosphere.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective coating layer creates an inert environment for the dielectric layer during reductive firing, shielding it from the harmful effects of the reductive atmosphere while allowing the Ni internal electrode to benefit from the reducing conditions.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Ease of manufacture

If Ni is used for internal electrodes, then manufacturing is simplified, but lifetime characteristic of the ceramic electronic device has room for improvement

Engineering Contradiction:

Improveinternal electrode manufacturingVSAvoiddevice lifetime

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent uses composite material structures by combining Ni with protective coating materials (SiO2, SiNx, or SiOxNy) to create a multi-layer internal electrode structure. This composite approach enables simultaneous achievement of oxidation resistance from Ni and protection against oxygen vacancy generation through the coating layer.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

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 addition of Sn and Au to the internal electrode layers improves the durability of the dielectric layers against high voltage, leading to extended lifespan and reduced variability in the multilayer ceramic capacitors, thereby enhancing the overall lifetime characteristic of the devices.

Implementation Method 1

suppressing Ni diffusion into the dielectric layers

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11948753B2Manufacturing method of multilayer ceramic electronic device

Publication Date: 2024.04.02 TAIYO YUDEN KK

AI summary

A manufacturing method of a multilayer ceramic electronic device includes: forming each of stack units by forming each of internal electrode patterns on each of dielectric green sheets, the each of internal electrode patterns including Ni, Sn and Au; forming a multilayer structure by stacking the each of stack units; and firing the multilayer structure, whereby each internal electrode layer is formed from the each of internal electrode patterns and each dielectric layer is formed from the each of the dielectric green sheets wherein, in the each internal electrode layer, an Au concentration near each interface between the each internal electrode layer and the each dielectric layer is larger than an Au concentration in each center portion in a thickness direction.