Core-Shell Dielectric Ceramic for Laminated Capacitor Reliability
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Solution Overview
Problem
Existing dielectric ceramic layers in laminated ceramic capacitors face challenges with high temperature characteristics, lifetime, and withstand voltage when made thinner, failing to meet X5R and X7R standards and maintaining satisfactory breakdown voltage and reliability.
Innovation Solution
A dielectric ceramic composition with a core-shell structure and homogeneous structure crystalline grains at an area ratio of 91:9 to 99:1, where the mean grain size ratio of homogeneous to core-shell grains is between 0.8 and 3, using Ba, Ti, and accessory components like La, Ce, and Mg, to enhance capacitance, reliability, and temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dielectric ceramic layers are made thinner to reduce size and increase capacitance, then capacitance increases and size reduces, but breakdown voltage decreases and reliability deteriorates
Solution Approach 1:
The patent applies local quality by creating core-shell structured crystalline grains where the core region and shell region have different compositions and properties. The core contains specific oxide components while the shell has different composition, allowing the grain interior to provide high dielectric constant while the shell provides high breakdown voltage resistance. This local differentiation enables thin layers to maintain high reliability.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components (including but not limited to BaTiO3, Pb(Zr,Ti)O3, Pb1-xLaxZr1-yTiyO3) to form core-shell structured crystalline grains. This composite structure at the grain level provides both high dielectric constant and high breakdown voltage, enabling thin capacitor layers to achieve both high capacitance and high reliability.
2Temperature
If the ratio of homogeneous structure grains is increased to improve temperature characteristics, then temperature characteristics improve, but grain growth occurs and lifetime characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating core-shell structured crystalline grains where the core region and shell region have different compositions and properties. The core contains specific oxide components while the shell has different composition, allowing the grain interior to provide high dielectric constant while the shell provides high breakdown voltage resistance. This local differentiation enables thin layers to maintain high reliability.
Solution Approach 2:
The patent changes parameters by precisely controlling the area ratio of core-shell grains to homogeneous grains within 91:9 to 99:1, and controlling the shell thickness ratio relative to grain size within 0.05 to 0.2. These parameter optimizations ensure that core-shell grains dominate to prevent grain growth while maintaining good temperature characteristics, thus improving lifetime without sacrificing temperature stability.
3Productivity
If dielectric ceramic layers are made thinner to improve capacitance density, then capacitance per volume increases, but withstand voltage characteristics become insufficient
Solution Approach 1:
The patent applies local quality by creating core-shell structured crystalline grains where the core region and shell region have different compositions and properties. The core contains specific oxide components while the shell has different composition, allowing the grain interior to provide high dielectric constant while the shell provides high breakdown voltage resistance. This local differentiation enables thin layers to maintain high reliability.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components (including but not limited to BaTiO3, Pb(Zr,Ti)O3, Pb1-xLaxZr1-yTiyO3) to form core-shell structured crystalline grains. This composite structure at the grain level provides both high dielectric constant and high breakdown voltage, enabling thin capacitor layers to achieve both high capacitance and high reliability.
Data Source
AI summary
A dielectric ceramic which improves the lifetime characteristics and dielectric breakdown voltage of a laminated ceramic capacitor includes core-shell crystalline grains which have a core-shell structure and homogeneous crystalline grains which have a homogeneous structure. In this dielectric ceramic, the core-shell crystalline grains and the homogeneous crystalline grains are present at an area ratio in the range of 91:9 to 99:1. Preferably, when the mean grain size for the core-shell crystalline grains is represented by R1 and the mean grain size for the homogeneous crystalline grains is represented by R2, the ratio of R2/R1 is 0.8 or more and 3 or less.