Barium Titanate Dielectric Ceramic for Thermal Shock Resistance
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Solution Overview
Problem
Laminated ceramic capacitors with reduced dielectric layer thickness and increased number of layers face inadequate thermal shock resistance, leading to potential cracking during mounting, which compromises their reliability.
Innovation Solution
Incorporating a dielectric ceramic with a barium titanate-based compound and secondary phase grains of Al, Mg, and Si, along with specific rare earth elements and additional elements, to enhance thermal shock resistance while maintaining dielectric and insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dielectric layer thickness is reduced and the number of layers is increased to reduce capacitor size and increase capacitance, then the capacitance and size requirements are met, but the thermal shock resistance deteriorates, leading to cracks during mounting
Solution Approach 1:
The patent uses a composite material system consisting of barium titanate-based dielectric ceramic combined with specific glass components (B2O3, SiO2, Al2O3) and metal oxide additives. This composite structure provides both the high dielectric constant needed for high capacitance density and the thermal shock resistance required for reliable mounting, resolving the contradiction between capacitance performance and thermal reliability in thin-layer capacitors
2Strength
If Al is added to improve mechanical strength, then the structural integrity is enhanced, but the thermal shock resistance remains insufficient, leading to cracking during mounting
Solution Approach 1:
The patent changes the chemical composition parameters by specifying precise ranges for glass components (B2O3: 30-70 wt%, SiO2: 10-40 wt%, Al2O3: 5-20 wt%) and metal oxide additives (0.1-5 wt% total). This parameter optimization achieves both improved mechanical strength from Al2O3 and sufficient thermal shock resistance through the borosilicate glass matrix, resolving the contradiction between strength and thermal shock resistance
Data Source
AI summary
A dielectric ceramic and a laminated ceramic capacitor using the dielectric ceramic are achieved which provide favorable thermal shock resistance without damaging properties or characteristics such as dielectric properties, insulation properties, temperature characteristics, and characteristics in high temperature loading, even when the dielectric layers are reduced in thickness and the number of stacked layers increased. The dielectric ceramic contains, as its main constituent, a barium titanate based compound represented by the general formula ABO3, and a crystalline oxide containing Al, Mg, and Si is present as secondary phase grains in the dielectric ceramic.