BaTiO3 Dielectric Composition for MLCC DC-Bias Reliability
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) face challenges in maintaining high permittivity and reliability when subjected to high field DC-bias, particularly due to the thinning of dielectric layers which affects DC-bias characteristics and high-temperature withstand voltage characteristics.
Innovation Solution
A dielectric composition based on a BaTiO3 main ingredient with auxiliary rare earth elements Dy and Eu, where the molar content ratios of Dy and Eu are optimized within specific ranges to enhance insulation resistance and temperature coefficient of capacitance, forming a core-shell structure to improve microstructural uniformity and high-temperature reliability.
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 size of the multilayer ceramic capacitor is reduced, but the DC-bias characteristics and high-temperature withstand voltage characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric layer by introducing specific rare earth elements (Dy and Eu) as auxiliary ingredients. The Dy content is controlled at 0.01-0.50 mol% and Eu content at 0.01-0.50 mol% based on 100 moles of BaTiO3-based main ingredient. This compositional parameter change enables the dielectric layer to maintain high insulation resistance and stable capacitance characteristics even at reduced thicknesses of 0.6 μm or less, thereby resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent creates a composite dielectric material by combining BaTiO3-based main ingredient with rare earth element auxiliaries (Dy and Eu). This composite structure leverages the high permittivity of BaTiO3 while the rare earth elements provide enhanced insulation resistance and thermal stability. The synergistic combination allows the thin dielectric layer to simultaneously achieve miniaturization goals and maintain excellent DC-bias and high-temperature withstand voltage characteristics.
2Quantity of substance
If the thickness of the dielectric layer is decreased to increase capacitance, then the capacitance per unit area increases, but the insulation resistance and reliability deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating rare earth elements Dy and Eu in optimized quantities (0.01-0.50 mol% each). This parameter change fundamentally alters the electrical properties of the dielectric material, enabling it to achieve high insulation resistance (>10^9 Ω at 50V) and stable capacitance characteristics even when the layer thickness is reduced to 0.6 μm or less, thus resolving the contradiction between increasing capacitance density and maintaining reliability.
Solution Approach 2:
The patent introduces local quality enhancement by concentrating rare earth elements at specific positions within the dielectric layer structure. The Dy and Eu elements are incorporated into the dielectric grain boundaries and interfaces, creating localized regions with enhanced insulation properties. This local quality improvement allows the thin dielectric layer to maintain high breakdown voltage and insulation resistance, enabling high capacitance density without sacrificing reliability.
3Volume of moving object
If the dielectric layer thickness is reduced to achieve smaller capacitor size, then the capacitor can be implemented with smaller dimensions, but the high-temperature withstand voltage characteristics worsen
Solution Approach 1:
The patent changes the thermal and electrical parameters of the dielectric material through the addition of rare earth elements. The Dy and Eu incorporation modifies the material's thermal stability and charge carrier concentration, resulting in enhanced high-temperature withstand voltage characteristics. This parameter change enables the thin dielectric layer to maintain stable electrical properties at elevated temperatures up to 150°C, resolving the contradiction between miniaturization and high-temperature performance.
Solution Approach 2:
The patent develops a composite dielectric system combining BaTiO3 with rare earth element oxides (Dy2O3 and Eu2O3). This composite material structure provides synergistic effects where the BaTiO3 matrix offers high permittivity while the rare earth element compounds enhance thermal stability and withstand voltage characteristics. The composite nature of the material allows the thin dielectric layer to simultaneously achieve small size and maintain excellent high-temperature electrical performance.
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
The optimized dielectric composition achieves high insulation resistance and temperature coefficient of capacitance characteristics, ensuring excellent DC-bias and high-temperature withstand voltage performance even at reduced thicknesses, thereby enhancing the reliability of MLCCs.
Implementation Method 1
the multilayer ceramic capacitor has recently been used in devices within various fields such as high-frequency circuits because it has excellent temperature and frequency characteristics
Implementation Method 2
it has excellent temperature and frequency characteristics
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, and an auxiliary ingredient including rare earth elements, wherein the rare earth elements include Dy and Eu, Dy and Eu molar contents based on 100 moles of the BaTiO3-based main ingredient satisfy conditions of 0.10<Eu/(Dy+Eu)≤0.50 and 0.60≤Dy+Eu≤1.0, and the rare earth elements do not include another element in a higher molar content than Dy and Eu.