Multilayer Ceramic Capacitor Grain Boundary Control
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Solution Overview
Problem
Existing multilayer ceramic capacitors face a trade-off between achieving high capacity and reliability, as making dielectric ceramic layers thinner compromises insulation resistance and reliability, while methods to enhance reliability often result in reduced capacity and temperature characteristics.
Innovation Solution
The solution involves controlling the thickness of crystal grain boundaries between ceramic grains in dielectric layers to a specific ratio, using barium titanate or barium calcium titanate with additives like magnesium oxide, manganese oxide, and rare earth oxides, to maintain high reliability and dielectric constant even when layers are made thin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric ceramic layers are made thin to achieve small size and high capacity, then the capacity and size are improved, but the insulation resistance and reliability deteriorate
Solution Approach 1:
The patent applies local quality by controlling the crystal grain boundary thickness specifically at the interfaces between ceramic grains, rather than uniformly thickening the entire dielectric layer. By making the crystal grain boundaries extremely thin (0.01-0.5 μm) in specific locations where grains adjoin, the patent maintains high capacity while improving insulation resistance and reliability at the critical interfaces where breakdown typically occurs.
Solution Approach 2:
The patent changes the physical parameter of crystal grain boundary thickness from conventional dimensions to extremely thin dimensions (0.01-0.5 μm). This parameter change fundamentally alters the electrical properties at grain boundaries, reducing insulation defects and improving reliability without sacrificing the high capacity enabled by thin overall dielectric layer thickness.
2Volume of moving object
If the dielectric ceramic layers are made thin to achieve small size, then the size is reduced, but the reliability deteriorates
Solution Approach 1:
The patent applies local quality by making the crystal grain boundaries extremely thin (0.01-0.5 μm) only at the critical interfaces between ceramic grains, while maintaining the overall thin dielectric layer structure (1-10 μm) for small size. This localized control of grain boundary thickness ensures high reliability at interfaces without compromising the size reduction achieved by thin overall layers.
3Reliability
If additives like Mn or Mg are added in large amounts to improve reliability, then the reliability may improve, but donor or acceptor ingredients segregate at crystal grain boundaries and insulation defects increase
Solution Approach 1:
The patent changes the parameter of crystal grain boundary thickness to extremely thin dimensions (0.01-0.5 μm), which fundamentally alters the behavior of additive elements. At such thin boundaries, the segregation of donor or acceptor ingredients is minimized, preventing the formation of insulation defects that would otherwise occur with conventional grain boundary thicknesses, even when additives are present.
Solution Approach 2:
The patent uses composite materials by combining barium titanate-based dielectric ceramic with controlled amounts of additives (Mn, Mg, etc.) and glass components. The extreme thinness of the crystal grain boundaries (0.01-0.5 μm) creates a unique composite structure where the additive elements do not segregate harmfully, allowing the composite to achieve both improved reliability and reduced insulation defects.
Data Source
AI summary
A multilayer ceramic capacitor 1 having dielectric layers 2 having barium titanate or barium calcium titanate as a main ingredient. When the dielectric layers are barium titanate, the ratio of the grains having a thickness of the crystal grain boundaries 22 present between adjoining dielectric grains 20 is 30% to 95% of the plurality of dielectric grains 20 forming the dielectric layers 2. When the dielectric layers 2 are barium calcium titanate, the ratio of the grains having a thickness of the crystal grain boundaries 22 present between adjoining dielectric grains 20 is 20% to 70% of the plurality of dielectric grains 20 forming the dielectric layers 2.