Dielectric ceramic composition and multilayer ceramic electronic device
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Solution Overview
Problem
Existing dielectric ceramic compositions for multilayer ceramic capacitors suffer from inadequate temperature characteristics and reliability due to improper composition and grain boundary properties, leading to reduced performance and longevity.
Innovation Solution
A dielectric ceramic composition comprising perovskite compounds with specific A-site and B-site elements, additional elements like Si, Al, Mn, and Cr, and controlled β/α ratios to optimize grain boundary properties, ensuring good temperature characteristics and high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric ceramic compositions are used, then manufacturing is simpler, but temperature characteristics and reliability are inadequate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional ratios of A-site elements (Ca, Sr, Ba) and B-site elements (Zr, Ti, Sn) in the perovskite structure, as well as controlling the β/α ratio of additional elements to be 3.0 or more and 6.0 or less. These parameter optimizations improve temperature characteristics and reliability while maintaining manageable composition complexity
Solution Approach 2:
The patent uses composite materials by combining perovskite compounds with specific additional elements (Si, Al, Mn, Cr, Nb, Ta) in controlled amounts. The grain boundary region contains a composite structure with perovskite phases and additional element oxides, creating a multi-phase composite that enhances both temperature stability and reliability
2Reliability
If grain boundary properties are not optimized, then composition is simpler, but oxygen vacancy movement occurs reducing reliability
Solution Approach 1:
The patent applies local quality by creating a specialized grain boundary region with distinct composition from the main phase. The grain boundary contains perovskite compounds and additional elements (Si, Al, Mn, Cr, Nb, Ta) in specific ratios, forming a localized structure that prevents oxygen vacancy movement and enhances reliability without complicating the overall composition
3Stability of the object's composition
If element segregation is not minimized, then manufacturing is easier, but temperature stability deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the β/α ratio of additional elements to be 3.0 or more and 6.0 or less, and controlling the content of additional elements to be 1.8 parts by mol or more and 5.0 parts by mol or less with respect to 100 parts by mol B-site elements. These parameter controls minimize element segregation and improve temperature stability
Data Source
AI summary
A dielectric ceramic composition includes main phase grains and a grain boundary between the main phase grains. The main phase grains include a perovskite compound as a main component. The perovskite compound includes at least Ca and Sr as A-site elements and at least Zr and Ti as B-site elements. The dielectric ceramic composition further includes an oxide of at least one additional element. β/α is 3.0 or more and 6.0 or less, where α (unit: parts by mol) denotes a content of the at least one additional element of the dielectric ceramic composition with respect to 100 parts by mol B-site elements, and β (unit: parts by mol) denotes a content of the at least one additional element of the grain boundary with respect to 100 parts by mol B-site elements.