Ni Base Plating Interface for MLCC Electrode Diffusion Control
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Solution Overview
Problem
The challenge in multilayer ceramic capacitors is the deterioration of connectivity between internal and external electrodes due to diffusion of Cu from external electrodes into internal electrodes, leading to volume expansion, radiation cracks, and hydrogen penetration, which is exacerbated by the thinning of dielectric and internal electrodes for miniaturization and high capacitance.
Innovation Solution
Incorporating base plating layers with Ni grains of 4 µm or greater between internal and external electrodes to suppress metal diffusion, improve connectivity, and prevent hydrogen penetration, while maintaining a dielectric layer thickness of 0.35 µm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of internal electrodes is reduced to increase the number of stacked layers for miniaturization and high capacitance, then the capacitance and miniaturization are improved, but the connectivity between internal electrodes and external electrodes deteriorates due to increased shrinkage
Solution Approach 1:
A base plating layer is introduced as an intermediary between the internal electrode and the external electrode. This base plating layer has a grain structure with an average grain size of 4 µm or more, which provides a stable interface that compensates for the shrinkage of thin internal electrodes, thereby maintaining good connectivity even when the internal electrode thickness is reduced to 0.35 µm or less.
Solution Approach 2:
The grain size parameter of the base plating layer is controlled to be 4 µm or more, which is significantly larger than the internal electrode thickness. This parameter change in the base plating layer's microstructure provides mechanical stability and reduces the negative effects of internal electrode shrinkage, enabling maintain connectivity despite reduced electrode thickness.
2Productivity
If the thickness of internal electrodes is reduced to increase the number of stacked layers, then the capacitance density is improved, but diffusion between Cu of external electrodes and Ni of internal electrodes increases causing volume expansion and radiation cracks
Solution Approach 1:
The base plating layer serves as a diffusion barrier and intermediary between the Cu external electrode and the Ni internal electrode. Its coarse grain structure (average grain size ≥4 µm) provides a stable interface that prevents Cu-Ni diffusion, thereby preventing volume expansion and radiation cracks that would otherwise occur in thin-multilayer structures.
3Productivity
If the number of stacked layers is increased for high capacitance, then the capacitance is improved, but hydrogen penetration into the body increases reducing reliability
Solution Approach 1:
The base plating layer with coarse grain structure acts as an intermediary barrier that suppresses hydrogen penetration into the ceramic body. This is particularly important in high-layer-count capacitors where the cumulative effect of multiple interfaces could allow hydrogen ingress, but the stable base plating layer prevents this.
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
Enhances reliability by preventing radiation cracks and improving connectivity between internal and external electrodes, even at reduced thicknesses, thus ensuring high capacitance and miniaturization.
Implementation Method 1
diffusion between Cu of external electrodes and Ni of the internal electrodes may increase
Implementation Method 2
penetration of hydrogen into a body is suppressed
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A multilayer electronic component includes a body (110) including a first external electrode (131) including a first base plating layer (131a) disposed on a third surface of the body and connected to the first internal electrode (121) and a first electrode layer (131b) disposed on the first base plating layer (131a), and a second external electrode (132) including a second base plating layer (132a) disposed on a fourth surface of the body (110) and connected to the second internal electrode (122) and a second electrode layer (132b) disposed on the second base plating layer (132a), wherein the first and second electrode layers (131b, 132b) include conductive metal and glass, and a 30 µm × 5 µm region selected from a cross-section of the first base plating layer (131a) in the first and second directions includes three or more Ni grains having a grain size of 4 µm or greater.