Multilayer Ceramic Electrode Core-Shell Structure Against Moisture Cracks
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with moisture penetration and cracking due to excessive formation of nickel-copper alloy regions, leading to reduced reliability and flexural strength.
Innovation Solution
The implementation of a core-shell region structure in internal electrodes, where the average content of the second metal (such as copper) differs between the core and shell portions, improving moisture resistance and preventing radial cracks by controlling volumetric expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel-copper alloy regions are formed at end portions of internal electrodes to improve coupling force, then moisture penetration is prevented, but radial cracking occurs due to volumetric expansion
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where only the end portions of internal electrodes form alloy regions with external electrodes, while the central portions remain as pure first metal. This localized alloying provides moisture resistance at critical interfaces without causing volumetric expansion throughout the entire electrode, thereby preventing radial cracking while maintaining coupling force.
Solution Approach 2:
The patent segments the internal electrode into distinct regions: a core portion made of first metal and shell portions at the ends that form alloy regions with external electrodes. This segmentation allows different functional zones within the same electrode structure, enabling moisture resistance at interfaces while maintaining structural integrity in the core.
2Reliability
If nickel-copper alloy regions are excessively formed, then coupling force is improved, but radial cracks occur due to excessive volumetric expansion
Solution Approach 1:
The patent applies partial action by forming alloy regions only at the end portions of internal electrodes where coupling with external electrodes is needed, rather than throughout the entire electrode. This controlled partial alloying provides sufficient coupling force while limiting volumetric expansion to avoid excessive stress that would cause radial cracking.
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 approach enhances moisture resistance reliability and high-temperature insulation resistance while preventing cracking, maintaining insulation resistance under humid conditions.
Implementation Method 1
a core-shell region including the first and second metals, and average contents of the second metals in a core portion and a shell portion of the core-shell region are different from each other
Data Source
AI summary
A multilayer ceramic electronic component includes: a body including dielectric layers as well as a plurality of internal electrodes stacked with respective dielectric layers interposed therebetween and including a first metal; and external electrodes disposed on external surfaces of the body including a second metal, wherein at least some of the plurality of internal electrodes include a core-shell region including the first and second metals, and average contents of the second metal in a core portion and a shell portion of the core-shell region are different from each other.