Dielectric Composition Grain Size Control for MLCC Permittivity
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving high reliability due to limitations in dielectric composition, including low permittivity and poor electrical properties, which are affected by the type and grain size of dielectric powders used, leading to issues with temperature stability and capacitance degradation.
Innovation Solution
A dielectric composition is developed comprising a first dielectric powder and a second dielectric powder with a smaller average grain size, along with specific accessory components like manganese, vanadium, and magnesium, optimized in weight ratios to enhance permittivity and electrical properties, while controlling grain growth and dissipation factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only a single type of dielectric powder is used in the dielectric composition, then the manufacturing process is simple, but the permittivity and electrical properties are insufficient
Solution Approach 1:
The patent uses a composite dielectric composition comprising two types of dielectric powders with different grain sizes (first dielectric powder with larger grain size and second dielectric powder with smaller grain size). This composite structure enables the dielectric layer to achieve high permittivity and excellent electrical properties by combining the advantages of both powder types, while the synergistic effect improves overall capacitor reliability without requiring complex manufacturing processes
2Manufacturing precision
If accessory components are added to control grain growth, then grain growth is controlled, but the composition complexity increases
Solution Approach 1:
The patent optimizes the grain size parameter by establishing a specific size ratio relationship between the two dielectric powders (b/a ≤ 1/10, where a is the average grain size of the first dielectric powder and b is the average grain size of the second dielectric powder). This parameter control prevents abnormal grain growth while maintaining high permittivity, and the accessory components further refine the grain size distribution to ensure stable electrical characteristics
Data Source
AI summary
A dielectric composition may include a first dielectric powder; and a second dielectric powder having an average grain size smaller than that of the first dielectric powder and included in the dielectric composition in an amount of 0.01 to 1.5 parts by weight based on 100 parts by weight of the first dielectric powder, and a multilayer ceramic capacitor formed using the same. A multilayer ceramic capacitor may include: a ceramic body including dielectric layers; first and second internal electrodes disposed in the ceramic body to face each other with the respective dielectric layers interposed therebetween; and first and second external electrodes electrically connected to the first and second internal electrodes, respectively. The dielectric layers are formed of a dielectric composition including a first dielectric powder and a second dielectric powder having an average grain size smaller than that of the first dielectric powder and included in the dielectric composition in an amount of 0.01 to 1.5 parts by weight based on 100 parts by weight of the first dielectric powder.