Core-Shell BaTiO3 Dielectric for X8R Multilayer Ceramic Capacitors
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in achieving high reliability and maintaining capacity stability at elevated temperatures, particularly above the Curie point of barium titanate, which limits their application in high-reliability electronic systems.
Innovation Solution
A dielectric body and multilayer ceramic capacitor design featuring crystal grains of barium titanate with a core-shell structure, where the shell has a higher Zr concentration than the core, and specific atomic concentration ratios of Zr, Eu, and Mn are maintained to enhance dielectric properties and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If barium titanate is used as the main dielectric material, then high dielectric constant is achieved, but capacity stability deteriorates at temperatures above the Curie point
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell region has different compositional characteristics than the core. The shell contains higher concentrations of Zr, Eu, and Mn elements, which locally modify the dielectric properties and stabilize the microstructure at elevated temperatures, while the core maintains the high dielectric constant barium titanate composition.
Solution Approach 2:
The patent uses composite materials by combining barium titanate with multiple dopant elements (Zr, Eu, Mn) in a core-shell configuration. This composite structure integrates the high dielectric constant of barium titanate with the temperature stability provided by the dopant-rich shell, achieving both high dielectric constant and capacity stability above the Curie point.
2Reliability
If Zr concentration in the shell is increased to improve reliability, then capacity stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating all necessary dopant elements (Zr, Eu, Mn) into the dielectric green sheet before lamination and stacking. The compositional ratios are predetermined in the raw materials, and the core-shell structure with higher Zr concentration in the shell is formed automatically during the firing process, eliminating the need for subsequent complex manufacturing steps.
Data Source
AI summary
A dielectric body includes a plurality of crystal grains of which a main component is barium titanate, and an additive including Zr, Eu and Mn. At least one of the plurality of crystal grains has a core-shell structure having a core and a shell. A Zr/Ti atomic concentration ratio is 0.02 or more and 0.10 or less. An Eu/Ti atomic concentration ratio is 0.001 or more and 0.03 or less. A Mn/Ti atomic concentration ratio is 0.005 or more and 0.05 or less.