Core-Shell Dielectric Composition for Thin-Layer MLCC DC-Bias Stability
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in maintaining high permittivity and reliability under high DC-bias conditions due to the thinning of dielectric layers, which leads to deteriorations in DC-bias characteristics and high-temperature withstand voltage characteristics.
Innovation Solution
A dielectric composition comprising a BaTiO3-based main ingredient with specific molar content ratios of rare earth elements (Tb and Dy or Gd and Dy) and auxiliary ingredients (Ba and Ca) forms a core-shell structure, optimizing the composition to enhance insulation resistance and temperature coefficient of capacitance (TCC) characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the dielectric layer is decreased to reduce capacitor size, then the capacitance increases and size decreases, but the DC-bias characteristics and high-temperature withstand voltage characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell portion has a different composition from the core portion. The shell contains specific rare earth elements (Tb, Dy, Gd) and auxiliary ingredients (Ba, Ca) in controlled molar ratios that provide enhanced insulation resistance and DC-bias characteristics, while the core provides the base dielectric properties. This localized compositional differentiation allows the thin dielectric layer to maintain high reliability despite reduced thickness.
Solution Approach 2:
The patent uses composite materials by combining BaTiO3-based main ingredient with specific auxiliary ingredients (rare earth elements Tb, Dy, Gd and Ba, Ca) in controlled molar ratios. The composite dielectric material exhibits synergistic effects where the rare earth elements enhance permittivity and the auxiliary ingredients improve insulation resistance, allowing the thin dielectric layer to achieve both high capacitance and high reliability under DC-bias conditions.
2Quantity of substance
If the thickness of the dielectric layer is decreased to increase capacitance, then the capacitance increases, but the reliability and high-temperature withstand voltage characteristics deteriorate
Solution Approach 1:
The shell portion with specific compositional characteristics provides localized enhancement of insulation resistance and reliability properties at the critical interfaces of the thin dielectric layer, allowing high capacitance to be achieved without sacrificing reliability.
Solution Approach 2:
The patent changes the chemical composition parameters by precisely controlling the molar ratios of auxiliary ingredients (0.40≤Tb/(Tb+Dy+Gd)≤0.60 and 0.05≤(Tb+Dy+Gd)/(Ba+Ca)≤0.50) to optimize both capacitance and reliability properties simultaneously in the thin dielectric layer.
3Quantity of substance
If a DC-bias field is applied to the MLCC, then the capacitance or permittivity decreases due to DC-bias characteristics, but high effective permittivity or capacitance under high field DC-bias is required for power management applications
Solution Approach 1:
The patent changes the compositional parameters by incorporating specific rare earth elements (Tb, Dy, Gd) in controlled molar ratios that modify the dielectric properties to maintain high permittivity and capacitance even under high DC-bias field conditions, enabling effective operation in power management applications.
Solution Approach 2:
The composite dielectric material with rare earth elements and auxiliary ingredients creates a structure that resists DC-bias induced degradation, maintaining stable capacitance and permittivity under high field conditions through the synergistic effects of the composite composition.
Data Source
AI summary
A dielectric composition and a multilayer capacitor including the same are disclosed. The dielectric composition including: a BaTiO3-based main ingredient; a first auxiliary ingredient including rare earth elements; and a second auxiliary ingredient including at least one of Ba and Ca but essentially including Ba, wherein the rare earth elements include Tb and Dy, and the first auxiliary ingredient and the second auxiliary ingredient satisfy a molar content condition of 0.40<(Tb/T_RE)*(Ba+Ca)<0.93, where T_RE is a total molar content of the rare earth elements in the first auxiliary ingredient.