Core-Shell Perovskite Dielectric Composition for MLCC
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Solution Overview
Problem
Current methods for producing fine-grained perovskite powders for multilayered ceramic capacitors face challenges in achieving uniform particle size and electrical reliability due to irregular crystalline structures and excessive particle growth during high-temperature firing, leading to insulation defects and deteriorated dielectric constants.
Innovation Solution
A dielectric composition comprising a first perovskite powder as a core and a second perovskite powder as a shell with a controlled particle diameter ratio and pore volume fraction, where the second powder has an average particle diameter of ⅓ to 1/10 of the first powder, and is included in amounts of 1 to 70 parts by weight, with the firing process conducted under a reduction atmosphere to form a uniform core-shell structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-temperature calcination is used to produce perovskite powder, then crystalline structure is formed, but particle size becomes irregular and requires additional grinding
Solution Approach 1:
The patent applies preliminary action by pre-forming perovskite crystalline particles with controlled size distribution before the calcination process. The co-precipitation method is used to create uniform precursor particles that maintain their size uniformity through calcination, thus achieving crystalline structure formation without significant particle size variation or need for additional grinding
2Volume of moving object
If the dielectric layer is thinned to achieve miniaturization, then device size is reduced, but surface roughness increases and short-circuit ratio increases
Solution Approach 1:
The patent uses hydraulic action (water jet) to grind and classify the perovskite powder, achieving fine and uniform particle size distribution. This produces a smooth dielectric layer with reduced surface roughness, enabling thinning while maintaining insulation performance and preventing short-circuits
Solution Approach 2:
The patent changes the particle size parameter of the perovskite powder to achieve an optimal distribution with D50 between 0.5-2.0 μm. This parameter optimization allows the dielectric layer to be made thinner while maintaining surface smoothness and electrical reliability
3Manufacturing precision
If fine-grained powder is used to achieve uniform structure, then particle size uniformity is improved, but particle growth occurs rapidly during firing
Solution Approach 1:
The patent performs preliminary size classification of perovskite particles before firing to ensure uniform particle size distribution. By pre-classifying particles to a narrow size range (D50: 0.5-2.0 μm, span: 0.7-1.3), the patent minimizes the driving force for particle growth during firing, maintaining size uniformity in the final product
4Volume of moving object
If fine particles are used, then dielectric layer can be made thinner, but solidification with additives during firing is easily generated
Solution Approach 1:
The patent applies local quality by using a core-shell structure where the core contains pure perovskite particles and the shell contains controlled amounts of additives. This localized additive distribution prevents excessive solidification while maintaining desired dielectric properties, allowing thin dielectric layers with high reliability
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 dielectric composition with improved dielectric and electrical characteristics, including reduced temperature coefficient of capacitance, enhanced dielectric constant, and increased reliability, by controlling the core-shell volume fraction and particle size distribution, thereby addressing the limitations of existing methods.
Implementation Method 1
particles of the second perovskite powder have pores having a volume fraction of 3 to 50 vol % therein
Implementation Method 2
the firing process conducted under a reduction atmosphere
Data Source
AI summary
There are provided a dielectric composition and a preparation method thereof, the dielectric composition including: a first perovskite powder for a core represented by ABO3: and a second perovskite powder for a shell represented by ABO3, having an average particle diameter corresponding to ⅓ to 1/10 of an average particle diameter of the first perovskite powder, and included in an amount of 1 to 70 parts by weight with respect to 100 parts by weight of the first perovskite powder, wherein particles of the second perovskite powder have pores having a volume fraction of 3 to 50 vol % therein. According to the present invention, there are provided a dielectric composition having excellent dielectric characteristics and electrical characteristics, and a preparation method thereof.