MLCC Side-Margin Zoning for Crack-Resistant High-Voltage Operation
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Solution Overview
Problem
Multi-layer ceramic capacitors face challenges in achieving sufficient withstand voltage characteristics while maintaining electrostatic capacity, particularly when high voltage is applied, as thin side margins can lead to structural defects like cracks due to electrolytic strain.
Innovation Solution
The capacitors incorporate a multi-layer unit with ceramic layers and internal electrodes, surrounded by first and second side margins. These side margins are divided into inner and outer regions, with higher concentrations of manganese and magnesium in the outer regions for enhanced mechanical strength and crystal refinement, and silicon in the inner regions to promote flexibility and suppress glass phase precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the side margin is made thinner to extend the crossing area of internal electrodes, then the miniaturization and capacity increase are achieved, but the withstand voltage characteristics deteriorate due to structural defects like cracks from electrolytic strain
Solution Approach 1:
The side margin is divided into first and second regions with different compositions. The first region (adjacent to ceramic layers) contains Si to suppress glass phase precipitation and maintain flexibility, while the second region (outer region) contains Mn and/or Mg to enhance mechanical strength and refine crystal grains. This local differentiation allows the thin side margin to resist electrolytic strain-induced cracks while maintaining overall miniaturization.
2Reliability
If Mn and/or Mg are added to the side margin to enhance mechanical strength and suppress cracks, then the withstand voltage characteristics improve, but the dielectric constant and electrostatic capacity decrease due to diffusion into ceramic layers
Solution Approach 1:
The side margin is divided into first and second regions with different compositions. The first region (adjacent to ceramic layers) contains Si to suppress glass phase precipitation and maintain flexibility, while the second region (outer region) contains Mn and/or Mg to enhance mechanical strength and refine crystal grains. This local differentiation allows the thin side margin to resist electrolytic strain-induced cracks while maintaining overall miniaturization.
Solution Approach 2:
The side margin is segmented into two distinct regions: a first region adjacent to the ceramic layers and a second outer region. This segmentation isolates the Mn/Mg-containing region from direct contact with ceramic layers, preventing harmful diffusion while maintaining the beneficial mechanical properties in the outer region.
3Quantity of substance
If Si is added to the side margin to suppress glass phase precipitation and maintain flexibility, then the electrostatic capacity is preserved, but the mechanical strength may be reduced
Solution Approach 1:
The side margin is divided into first and second regions with different compositions. The first region (adjacent to ceramic layers) contains Si to suppress glass phase precipitation and maintain flexibility, while the second region (outer region) contains Mn and/or Mg to enhance mechanical strength and refine crystal grains. This local differentiation allows the thin side margin to resist electrolytic strain-induced cracks while maintaining overall miniaturization.
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 configuration effectively improves the withstand voltage characteristics by releasing stress through the flexible inner regions and preventing cracks in the mechanically strong outer regions, while also maintaining electrostatic capacity and suppressing the decrease in dielectric constant.
Implementation Method 1
the added element diffuses into the ceramic layer of the multi-layer unit to reduce the dielectric constant of the ceramic layer
Implementation Method 2
promote densification of ceramics
Implementation Method 3
silicon in the inner regions to promote flexibility and suppress glass phase precipitation
Implementation Method 4
a multi-layer unit includes a plurality of ceramic layers laminated in a direction of a first axis and a plurality of internal electrodes disposed between the plurality of ceramic layers
Data Source
AI summary
A multi-layer ceramic capacitor includes: a multi-layer unit including ceramic layers laminated in a first direction and electrodes disposed between the ceramic layers, positions of end portions of the electrodes falling within a range of 0.5 μm in a second direction; and side margins each containing manganese or magnesium and silicon and facing each other in the second direction. When each margin is equally divided into an inner region and an outer region, a total concentration of manganese and magnesium in the outer region is higher than a total concentration of manganese and magnesium in the inner region and higher than a total concentration of manganese and magnesium in the ceramic layers, and a concentration of silicon in the inner region is not less than a concentration of silicon in the outer region and higher than a concentration of silicon in the ceramic layers.