Multilayer Ceramic Capacitor Grain Size Control

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Solution Overview

Problem

Multilayer ceramic capacitors face challenges in maintaining moisture-resistance properties due to the thinning of cover layers, which increases the risk of moisture infiltration and degradation of reliability as the internal electrodes become thinner and more highly laminated.

Innovation Solution

A multilayer ceramic component design where the average diameter of ceramic grains in the cover area is smaller than in the active area, with a thickness ratio of cover area to ceramic grain diameter (Tc/Dc) greater than or equal to 55, and a method of manufacturing involving different grain sizes for the active and cover areas to control sintering temperatures and stress distribution, using barium titanate or strontium titanate dielectric materials and internal electrodes made of nickel or palladium alloys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the cover layer thickness is decreased to achieve miniaturization and high lamination, then the capacitance increases, but the moisture-resistance properties deteriorate

Engineering Contradiction:

ImprovecapacitanceVSAvoidmoisture-resistance properties

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating two distinct regions within the ceramic body: an active area with larger ceramic grains for high capacitance, and a cover area with smaller ceramic grains for enhanced moisture resistance. This spatial differentiation of material properties resolves the contradiction between miniaturization and moisture protection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the ceramic grain diameter parameter between different regions. By controlling the average ceramic grain diameter to be smaller in the cover area (Dc) compared to the active area (Da), with Da/Dc ratio between 1.1-4.4, the patent achieves both high capacitance and improved moisture resistance even with reduced cover layer thickness.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the cover layer is thinned to increase internal electrode lamination density, then the capacitance increases, but moisture infiltration risk increases

Engineering Contradiction:

Improveinternal electrode lamination densityVSAvoidmoisture infiltration

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements local quality by differentiating the ceramic grain structure between the active area (higher lamination density with larger grains) and the cover area (protective layer with smaller grains). This allows high lamination density for productivity while maintaining moisture barrier properties.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite microstructure within the ceramic body, combining regions with different ceramic grain sizes and properties. The cover area with finer grains acts as a protective composite layer that resists moisture infiltration while allowing the active area to maintain high lamination density.

Inventive Principle:

Principle #40Composite materials

3Volume of moving object

If the cover layer thickness is reduced for miniaturization, then the component size decreases, but delamination risk increases under thermal impact

Engineering Contradiction:

Improvecomponent sizeVSAvoiddelamination resistance

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a cover area with smaller ceramic grains that has different thermal and mechanical properties compared to the active area. This localized structural differentiation reduces non-uniform stress distribution during thermal cycling, preventing delamination even with reduced cover layer thickness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the ceramic grain size parameter in the cover area to be smaller (Dc) than in the active area (Da). This parameter change affects the thermal expansion and stress characteristics, reducing stress concentration at interfaces and improving delamination resistance despite miniaturization.

Inventive Principle:

Principle #35Parameter changes

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 enhances moisture-resistance properties and reliability by reducing non-uniform stress distribution and preventing delamination, even under thermal impacts, while maintaining high capacitance capabilities.

Implementation Method 1

reducing non-uniform stress distribution and preventing delamination, even under thermal impacts

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a method of manufacturing involving different grain sizes for the active and cover areas to control sintering temperatures

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS9042080B2Multilayer ceramic electronic component and method of manufacturing the same

Publication Date: 2015.05.26 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

There are provided a multilayer ceramic electronic component and a method of manufacturing the same. Here, an average diameter (Dc) of ceramic grains in a cover area is smaller than an average diameter (Da) of ceramic grains in the active area, and when a thickness of the cover area is expressed by Tc, 9 um≦Tc≦25 um and Tc/Dc≧55 are satisfied. A multilayer ceramic capacitor having excellent moisture-resistance properties may be obtained.