Multilayer Capacitor Dielectric Composition for Grain Growth Control
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving high capacitance and reliability due to excessive grain growth in dielectric layers, leading to decreased withstand voltage and high-temperature reliability when using fine powders, which complicates the sintering process and results in reduced effective capacitance.
Innovation Solution
The use of a dielectric material expressed by the empirical formula BaM1aTi1-xSnxM2bO3, where M1 includes a rare earth element like Dy, M2 includes Mn or V, and additional components like Al and Si, with a core-shell structure and optimized Sn content, to control grain size and enhance dielectric constant and withstand voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fine powders are used to decrease dielectric layer thickness, then capacitance increases, but grain growth becomes excessive leading to decreased withstand voltage and high-temperature reliability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition of the dielectric material. Specifically, it uses a barium titanate-based dielectric with controlled doping of rare earth elements (0.001-0.01 mole ratio), iron (0.001-0.01 mole ratio), and aluminum (0.001-0.01 mole ratio). This compositional parameter optimization enables the dielectric layer to maintain high capacitance while suppressing excessive grain growth, thereby preserving withstand voltage and high-temperature reliability even at reduced thicknesses.
Solution Approach 2:
The patent employs composite materials by creating a multi-component dielectric system based on barium titanate with controlled incorporation of rare earth elements, iron, and aluminum. This composite approach allows the material to exhibit both high dielectric constant (for high capacitance) and controlled grain growth characteristics (for maintained reliability). The synergistic combination of multiple elements in specific proportions resolves the contradiction between increasing capacitance and maintaining withstand voltage.
2Quantity of substance
If dielectric layer thickness is decreased to achieve smaller capacitor size, then capacitance density increases, but grain growth control becomes difficult and reliability decreases
Solution Approach 1:
The patent utilizes parameter changes by optimizing the chemical composition parameters of the dielectric material. The controlled doping levels of rare earth elements (0.001-0.01 mole ratio), iron (0.001-0.01 mole ratio), and aluminum (0.001-0.01 mole ratio) serve as critical parameters that regulate grain growth behavior. These compositional parameters enable precise control over grain size even in thin dielectric layers, maintaining manufacturing precision and reliability while achieving high capacitance density.
Solution Approach 2:
The patent applies preliminary action by pre-doping the dielectric material with specific amounts of rare earth elements, iron, and aluminum before the sintering process. This preliminary compositional preparation ensures that during subsequent sintering, the grain growth is inherently controlled without requiring complex process adjustments. The pre-established chemical composition acts as a foundation that guides grain development, making thin-layer fabrication more controllable and reliable.
3Ease of manufacture
If conventional dielectric materials are used, then manufacturing process is simple, but high-frequency performance and reliability are insufficient
Solution Approach 1:
The patent employs composite materials by developing a barium titanate-based dielectric with controlled multi-element doping (rare earth elements, iron, aluminum). This composite material structure maintains compatibility with conventional manufacturing processes while significantly enhancing high-frequency performance and reliability. The composite composition allows the material to exhibit superior dielectric properties and grain growth control without requiring fundamental changes to the manufacturing approach.
Solution Approach 2:
The patent applies parameter changes by optimizing the chemical composition parameters within conventional manufacturing capabilities. The controlled doping levels of rare earth elements (0.001-0.01 mole ratio), iron (0.001-0.01 mole ratio), and aluminum (0.001-0.01 mole ratio) represent parameter adjustments that can be implemented using existing manufacturing techniques. These parameter optimizations enable the material to achieve enhanced high-frequency performance and reliability while maintaining ease of manufacture.
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 approach results in a multilayer capacitor with improved high-frequency performance, enhanced reliability, and increased capacitance by suppressing excessive grain growth and ensuring high dielectric constant and withstand voltage even with thinner dielectric layers.
Implementation Method 1
a dielectric having a high dielectric constant such as a barium titanate is used between electrodes
Data Source
AI summary
A multilayer capacitor includes a body including a plurality of dielectric layers, and a plurality of internal electrodes stacked with one of the dielectric layers interposed therebetween, and external electrodes disposed on external surfaces of the body and connected to the internal electrodes, respectively. The plurality of dielectric layers include a dielectric expressed by empirical formula BaM1aTi1-xSnxM2bO3 (0.008≤x≤0.05, 0.006≤a≤0.03, and 0.0006≤b<0.006) in which M1 includes a rare earth element, and M2 includes at least one of Mn or V.