Core-Shell Dielectric Grains for High Capacitance MLCCs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayer ceramic capacitors face challenges in miniaturization and increasing capacitance due to limitations in dielectric constant, particularly with barium titanate (BaTiO3), and the absence of domain walls in the shell structure of core-shell dielectric grains restricts achieving high dielectric constants.
Innovation Solution
Incorporating a core-shell structure in dielectric grains with domain walls present in the shell, utilizing specific accessory components to enhance sinterability and dielectric constant, and optimizing the content and distribution of these components to stabilize the lattice structure during sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the dielectric layer is decreased to achieve miniaturization and increased capacitance, then the size of the capacitor is reduced and capacitance is increased, but the reliability and sinterability deteriorate
Solution Approach 1:
The dielectric grain is divided into core and shell regions with different compositions and properties. The core region contains barium titanate with high dielectric constant for capacitance enhancement, while the shell region contains additives for improved reliability and sinterability. This local differentiation allows each region to optimize its function independently.
Solution Approach 2:
The dielectric grain is formed as a composite structure combining barium titanate core material with shell materials containing specific additives. This composite approach integrates the high dielectric constant property of barium titanate with the reliability-enhancing properties of the shell additives, achieving both miniaturization and improved performance.
2Reliability
If additives are added to the dielectric material to improve reliability and sinterability, then the reliability is improved, but the dielectric constant decreases due to absence of domain walls in the shell structure
Solution Approach 1:
The dielectric grain is segmented into core and shell portions with distinct functions. The core portion maintains high dielectric constant by preserving domain walls, while the shell portion contains additives for reliability improvement. This segmentation allows both requirements to be satisfied simultaneously without mutual interference.
Solution Approach 2:
Different regions of the dielectric grain are assigned different qualities: the core region is optimized for high dielectric constant with pure barium titanate structure, while the shell region is optimized for reliability with additive-containing composition. This local quality differentiation resolves the contradiction between dielectric constant and reliability.
Data Source
AI summary
A multilayer ceramic capacitor includes: a ceramic body including dielectric layers and first and second internal electrodes disposed to face each other with each of the dielectric layers interposed therebetween; and first and second external electrodes disposed on external surfaces of the ceramic body and electrically connected to the first and second internal electrode, respectively, wherein the dielectric layer includes dielectric grains having a core-shell structure including a core and a shell, and a domain wall is disposed in the shell.