Dielectric Ceramic Si Distribution for Capacitor Size
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Solution Overview
Problem
Thinner dielectric ceramic layers in laminated ceramic capacitors increase electric field strength, leading to a decrease in dielectric constant, while grain growth to reduce grain boundaries degrades temperature characteristics of capacitance.
Innovation Solution
A dielectric ceramic with a main component of ABO3 (containing Ba and Ti) and Si as an accessory component, where Si is predominantly in secondary phase grains, increasing their ratio to 40% or more, reducing the low dielectric constant phase's impact and enhancing uniformity and insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric ceramic layer is made thinner to reduce capacitor size, then the capacitance increases, but the electric field strength increases which causes the dielectric constant to decrease
Solution Approach 1:
The patent applies local quality by creating distinct regions with different Si content distributions: main phase grains with lower Si content (0.1-1.0 wt%) and secondary phase grains with higher Si content (1.0-3.0 wt%). This non-uniform distribution allows the dielectric ceramic to maintain high dielectric constant in the main phase regions while the secondary phase regions provide structural stability, resolving the contradiction between thin layer design and dielectric constant maintenance.
Solution Approach 2:
The patent uses composite materials by forming a two-phase microstructure consisting of main phase grains (ABO3 with low Si content) and secondary phase grains (high Si content). This composite structure combines the high dielectric constant properties of the main phase with the structural stability of the Si-rich secondary phase, enabling thin layer design without sacrificing dielectric performance.
2Quantity of substance
If grain growth is promoted to reduce the number of grain boundaries, then the dielectric constant increases, but the temperature characteristic of capacitance is degraded
Solution Approach 1:
The patent applies local quality by creating distinct regions with different Si content distributions: main phase grains with lower Si content (0.1-1.0 wt%) and secondary phase grains with higher Si content (1.0-3.0 wt%). This non-uniform distribution allows the dielectric ceramic to maintain high dielectric constant in the main phase regions while the secondary phase regions provide structural stability, resolving the contradiction between thin layer design and dielectric constant maintenance.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the Si content in different phases: main phase grains contain 0.1-1.0 wt% Si while secondary phase grains contain 1.0-3.0 wt% Si. This parameter differentiation creates a microstructure that achieves both high dielectric constant and stable temperature characteristics, as the secondary phase acts as a buffer against temperature-induced grain boundary effects.
Data Source
AI summary
A dielectric ceramic containing ABO3 in which A is Ba, possibly with at least one of Ca and Sr, and B is Ti, possibly with at least one of Zr and Hf as its main component, and Si as a accessory component. The dielectric ceramic includes main phase grains containing the ABO3 main component and secondary phase grains having a composition different from that of the main phase grains. The ratio of the Si content in the secondary phase grains to the total content of Si in the dielectric ceramic is 40% or more so that more Si is distributed in the secondary phase grains. It is preferable that the Si content in secondary phase grains be 30 mol % or more.