Multilayer Capacitor Grain Size Segmentation for Moisture Resistance

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Solution Overview

Problem

Multilayer ceramic capacitors face challenges in achieving sufficient capacitance and moisture resistance reliability due to size constraints and stress-related issues during board mounting, limiting the number of stacked internal electrodes and compromising reliability.

Innovation Solution

A multilayer capacitor design featuring a body with stacked dielectric layers and internal electrodes, where the average grain size of the dielectric layer differs between the active and side margin portions, with the side margin portion extending to cover internal electrodes and external electrodes, ensuring uniform exposure lengths and improved moisture resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of the multilayer capacitor is reduced, then the compactness is improved, but the number of stacked internal electrodes is limited and capacitance cannot be secured

Engineering Contradiction:

Improvesize of capacitorVSAvoidnumber of stacked internal electrodes

Core Design Contradiction:

Volume of moving objectVSQuantity of substance

Solution Approach 1:

The capacitor body is divided into an active portion containing internal electrodes and a side margin portion without internal electrodes. This segmentation allows the internal electrodes to be stacked densely in the active portion while the side margin portion provides structural support and stress relief, enabling compact design without compromising capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the capacitor are designed with different dielectric layer configurations. The active portion has dielectric layers optimized for capacitance with larger grain sizes, while the side margin portion has dielectric layers optimized for mechanical strength and stress resistance with smaller grain sizes, allowing each region to perform its specific function optimally.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the number of stacked internal electrodes is increased to achieve intended capacitance, then the capacitance is improved, but stress during board mounting increases and moisture resistance reliability deteriorates

Engineering Contradiction:

Improvenumber of stacked internal electrodesVSAvoidmoisture resistance reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

By separating the capacitor into active and side margin portions, the internal electrodes are concentrated in the active portion where they are needed for capacitance, while the side margin portion acts as a buffer zone that absorbs mounting stress and prevents crack propagation, thereby maintaining reliability even with increased electrode stacking.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The side margin portion is designed beforehand to provide mechanical cushioning and stress distribution. This pre-designed structural buffer prevents stress concentration at critical interfaces during board mounting, protecting the internal electrodes and dielectric layers from damage before stress can cause failure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of moving object

If the dielectric layer is made thin to reduce component size, then the compactness is improved, but the mechanical strength and resistance to external influences are reduced

Engineering Contradiction:

Improvecomponent sizeVSAvoidmechanical strength of dielectric layer

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The dielectric layers in the active portion and side margin portion are designed with different properties. The active portion uses dielectric layers with larger grain sizes for optimal capacitance, while the side margin portion uses dielectric layers with smaller grain sizes and different compositions to enhance mechanical strength and stress resistance, compensating for the thinness of the overall structure.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11557438B2Multilayer capacitor

Publication Date: 2023.01.17 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

A multilayer capacitor includes a body including a multilayer structure in which a plurality of dielectric layers are stacked, and further including a plurality of internal electrodes having a dielectric layer interposed therebetween and external electrodes disposed on external surfaces of the body and connected to the internal electrodes. The body further includes an active portion in which the plurality of internal electrodes are located to form capacitance and a side margin portion covering a first surface and a second surface of the active portion opposing each other. An average grain size of a dielectric layer included in the active portion is different from an average grain size of a dielectric layer included in the margin portion. The side margin portion includes an extending portion extending between the external electrodes and the internal electrodes to cover a portion of the internal electrodes.