Multilayer Ceramic Capacitor Thickness Variation Design

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Solution Overview

Problem

Existing multilayer ceramic capacitors face reliability issues due to insufficient thickness of dielectric ceramic layers used for level difference elimination, leading to decreased capacitance and performance.

Innovation Solution

A multilayer ceramic capacitor design that includes a dielectric ceramic layer structure with specific thickness variations and compositions, where the second dielectric ceramic layer overlaps the first dielectric ceramic layer, and the third dielectric ceramic layer is used to sandwich the internal electrode layers, ensuring a sufficient thickness for level difference elimination and improved reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the thickness of the side margin is reduced to increase the area of internal electrode layers, then the capacitance increases, but the reliability decreases due to insufficient dielectric ceramic layer thickness for level difference elimination

Engineering Contradiction:

ImprovecapacitanceVSAvoidreliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The dielectric ceramic layer is divided into two distinct segments: a first dielectric ceramic layer with thickness T1 and a second dielectric ceramic layer with thickness T2, where T2 > T1. This segmentation allows the first layer to provide sufficient level difference elimination for reliability while the second layer maximizes the effective capacitance area, resolving the contradiction between reliability and capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the dielectric ceramic structure are assigned different thicknesses based on their functional requirements. The first dielectric ceramic layer has a smaller thickness optimized for capacitance generation, while the second dielectric ceramic layer has a larger thickness optimized for level difference elimination and reliability. This local differentiation resolves the contradiction by optimizing each region for its specific function.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a dielectric laminated sheet is applied to the side surface to eliminate level differences, then the manufacturing process is simplified, but the device thickness becomes insufficient after firing, decreasing reliability

Engineering Contradiction:

Improvemanufacturing processVSAvoiddevice thickness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The second dielectric ceramic layer is incorporated into the green sheet structure before stacking and firing, rather than being added as a separate post-firing component. This preliminary inclusion ensures that the sufficient thickness for level difference elimination is established before firing, preventing thickness reduction and maintaining reliability while keeping the manufacturing process simple.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dielectric ceramic structure uses a composite arrangement of two dielectric ceramic layers with different thicknesses, where the second layer provides enhanced thickness for reliability. This composite structure maintains the simplicity of the green sheet manufacturing process while ensuring sufficient device thickness after firing.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the dielectric ceramic layer thickness is increased to improve reliability, then the device thickness is sufficient, but the area of internal electrode layers decreases, reducing capacitance

Engineering Contradiction:

Improvedevice thicknessVSAvoidcapacitance

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The dielectric ceramic layer is segmented into two functional layers with different thicknesses. The first layer provides sufficient thickness for level difference elimination and reliability, while the second layer maximizes the area available for internal electrode layers, thereby maintaining high capacitance. This segmentation resolves the contradiction between reliability and capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different thicknesses are assigned to different regions of the dielectric ceramic structure based on local functional requirements. The first dielectric ceramic layer has a smaller thickness optimized for capacitance, while the second layer has a larger thickness optimized for reliability. This local quality differentiation allows simultaneous optimization of both reliability and capacitance.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11450484B2Multilayer ceramic capacitor

Publication Date: 2022.09.20 MURATA MFG CO LTD

AI summary

In a multilayer ceramic capacitor includes, in a plane including a center portion in a length direction, and a stacking direction and a width direction of a first dielectric ceramic layer, where a thickness at a center portion in the stacking direction is T1, a thickness at an end of the first dielectric ceramic layer in the width direction is T2, and respective thicknesses between an end of a first internal electrode layer in the length direction not connected to a second external electrode, and the second external electrode, and between an end of the second internal electrode layer in the length direction not connected to the first external electrode, and the first external electrode is T3, a difference in thickness between T1 and T2 is within about 10% of T1, and a thickness of T3 is greater than T1 and T2 and a difference thereof is about 10% or more of T1 and T2.