Core-Shell Dielectric Powder for High-Field MLCC Reliability
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Solution Overview
Problem
The miniaturization and increased capacity of multilayer ceramic capacitors lead to higher electric field intensities, causing reduced reliability due to increased leakage current and insufficient high-temperature load life, especially when the concentration gradient of rare earth elements and magnesium in the shell is uneven, and particle size distribution results in thin shells.
Innovation Solution
A dielectric powder composed of barium titanate with specific solid-solution ranges of rare earth elements (0.3-2.0% and magnesium (0.1-1.0%) is used, along with a core-shell grain structure in the dielectric layers, maintaining electrical neutrality and suppressing oxide ion vacancies to reduce leakage current and enhance high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dielectric layer is thinned to achieve miniaturization and increased capacity, then the capacitor capacity increases, but the electric field intensity increases causing reduced reliability
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell portion has a different composition (higher concentration of rare earth elements and magnesium) than the core portion. This localized compositional variation allows the shell to provide enhanced reliability and leakage current suppression specifically at the grain boundaries and surfaces, while the core maintains the primary dielectric function. The shell thickness is controlled to be 1-10 nm to optimize this local protective effect.
Solution Approach 2:
The patent uses composite materials by combining barium titanate with rare earth elements (such as lanthanum, cerium, neodymium) and magnesium to form a core-shell structured ceramic powder. The core consists of barium titanate with specific compositional ranges, while the shell contains higher concentrations of additives (0.01-5 at% rare earth elements and 0.01-2 at% magnesium). This composite structure enables the material to simultaneously achieve high capacitance and improved reliability under high electric field conditions.
2Reliability
If the concentration gradient of rare earth elements and magnesium in the shell increases to improve high-temperature load life, then reliability improves, but the concentration in the shell near the core decreases and some parts of the shell become thin due to particle size distribution
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional parameters of the core and shell portions. The core contains 0.003-0.03 at% rare earth elements and 0.003-0.01 at% magnesium, while the shell contains 0.01-5 at% rare earth elements and 0.01-2 at% magnesium. By adjusting these concentration parameters and the shell thickness (1-10 nm), the patent optimizes the balance between reliability improvement and shell thickness uniformity, ensuring adequate protective coverage even with particle size distribution.
3Productivity
If a high electric field strength is applied to meet miniaturization requirements, then capacitor capacity increases, but leakage current increases reducing high-temperature load life
Solution Approach 1:
The patent converts the potentially harmful effect of high electric field intensity into a benefit by using it to enhance the functional performance of the shell portion. The high electric field strength (achieved through miniaturization and thinning) actually promotes the formation and effectiveness of the core-shell structure, where the shell's elevated rare earth element and magnesium concentrations become more effective at suppressing leakage current under these high-field conditions, thereby improving high-temperature load life despite the increased electric field stress.
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 solution stabilizes temperature characteristics, maintains electrical neutrality, and reduces leakage current, ensuring a long high-temperature load life even under high electric field strengths.
Implementation Method 1
at least one type of rare earth element that is solid-solved at 0.3 at % or more and 2.0 at % or less with respect to titanium; and magnesium that is solid-solved at 0.1 at % or more and 1.0 at % or less with respect to titanium
Implementation Method 2
forming slurry of which a main component is barium titanate, by solid phase reaction of the at least one type of rare earth element, the magnesium, the barium compound and the titanium compound; and solid-solving the at least one type of tare earth element in the barium titanate by thermal treatment of the slurry
Data Source
AI summary
A dielectric powder includes barium titanate as a main component, at least one type of rare earth element that is solid-solved at 0.3 at % or more and 2.0 at % or less with respect to titanium, and magnesium that is solid-solved at 0.1 at % or more and 1.0 at % or less with respect to titanium.