MLCC Flex Crack Mitigation Voids

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Solution Overview

Problem

Multilayer ceramic capacitors (MLCCs) face significant failures due to flex cracks, which lead to insulation failures and 'short-circuit' issues, especially in harsh environments, and current designs are not effective in mitigating these failures without being design-specific.

Innovation Solution

The capacitor design incorporates crack mitigation voids between the lower face and the first plate, which channels stress cracks away from the conductive electrodes, minimizing damage and allowing stress relief without requiring significant changes to manufacturing equipment or processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional capacitor designs are used without crack mitigation features, then manufacturing simplicity is maintained, but flex crack failures occur leading to insulation failures and short-circuit issues

Engineering Contradiction:

Improveflex crack resistanceVSAvoidcapacitor structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The capacitor structure is segmented by introducing voids that divide the continuous electrode path into separate sections. These voids act as discontinuities that prevent crack propagation from reaching critical electrodes, thereby improving reliability without significantly complicating the overall manufacturing process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Voids are introduced as intermediary elements between the flexing substrate and the conductive electrodes. These voids serve as stress relief zones that absorb mechanical energy and prevent direct stress transmission to the electrodes, mitigating flex crack failures while maintaining manufacturing simplicity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If crack mitigation voids are introduced, then flex crack failures are mitigated, but manufacturing complexity increases

Engineering Contradiction:

Improveinsulation failure resistanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Voids are pre-formed in the capacitor structure during the manufacturing process before the capacitor is put into service. This preliminary action ensures that the stress relief features are already in place to prevent flex crack failures, maintaining ease of manufacture while improving reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The capacitor incorporates a porous structure with controlled voids that provide stress relief while maintaining electrical functionality. This porous design allows for crack mitigation without significantly increasing manufacturing complexity, as the voids can be formed using standard ceramic processing techniques

Inventive Principle:

Principle #31Porous materials

3Reliability

If crack mitigation voids are introduced, then stress cracks are channeled to non-damaging locations, but device complexity increases

Engineering Contradiction:

Improveshort-circuit resistanceVSAvoidelectrode configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The capacitor structure incorporates local variations in density and porosity at specific locations where voids are strategically positioned. These local quality changes create preferred crack propagation paths that redirect stress cracks away from critical electrodes, improving short-circuit resistance while maintaining relatively simple overall device architecture

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8713770B2Capacitor comprising flex crack mitigation voids

Publication Date: 2014.05.06 KEMET ELECTRONICS CORP

AI summary

A ceramic multilayer surface-mount capacitor with inherent crack mitigation void patterning to channel flex cracks into a safe zone, thereby negating any electrical failures.