MLCC Side-Margin Zoning for Withstand Voltage and Capacitance
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Solution Overview
Problem
Multi-layer ceramic capacitors face challenges in achieving high withstand voltage characteristics while maintaining electrostatic capacity due to electrolytic strain causing structural defects and dielectric constant reduction when thin side margins are used, and the addition of Mg or Mn can further decrease electrostatic capacity.
Innovation Solution
The use of side margins with specific compositions, where the outer region has a higher concentration of Mn or Mg for densification and mechanical strength, and the inner region has a higher concentration of Si for flexibility, helps in suppressing structural defects and maintaining electrostatic capacity, with the concentration of Mn and Mg being lower in the inner region to prevent diffusion into the ceramic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin side margin is used to extend the crossing area of internal electrodes, then the miniaturization and capacity increase are achieved, but structural defects such as cracks occur due to stress from electrolytic strain and withstand voltage characteristics deteriorate
Solution Approach 1:
The side margin is divided into two regions with different compositions: a first region containing Mn and/or Mg for mechanical strength, and a second region containing Si for flexibility and stress release. This local differentiation allows the thin side margin to simultaneously provide structural integrity and stress accommodation, preventing cracks while maintaining miniaturization.
2Strength
If Mn or Mg is added to the side margin to promote densification and improve mechanical strength, then withstand voltage characteristics improve, but the added elements diffuse into the ceramic layer reducing the dielectric constant and electrostatic capacity
Solution Approach 1:
The side margin is segmented into two distinct compositional regions: the first region contains Mn and/or Mg for densification and mechanical strength, while the second region contains Si to prevent diffusion of Mn/Mg into the ceramic layer. This segmentation allows the beneficial effects of Mn/Mg without the harmful diffusion that would reduce electrostatic capacity.
Solution Approach 2:
Silicon in the second region acts as an intermediary barrier that prevents the diffusion of Mn and Mg from the side margin into the ceramic layer. This intermediary layer maintains the dielectric constant of the ceramic layer while still allowing the first region to provide the necessary mechanical strength.
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 enhances the withstand voltage characteristics and electrostatic capacity of the multi-layer ceramic capacitor by reducing stress-induced defects and maintaining the dielectric constant, while also improving wear resistance and reducing the appearance of defects.
Implementation Method 1
refinement of crystal grains and densification of ceramics in the first outer region are promoted
Implementation Method 2
the glass phase is likely to precipitate in the first inner region
Implementation Method 3
in the case where a high voltage is applied to the internal electrodes, the ferroelectricity of the ceramic layer can cause electrolytic strain
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.