Multilayer Ceramic Capacitor Dielectric Composition for High Temperature Reliability
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues with high field intensity due to thinning of dielectric layers, particularly during voltage application and high temperature load tests, as existing dielectric ceramics do not ensure high reliability when used in miniaturized capacitors.
Innovation Solution
A multilayer ceramic capacitor composition featuring a perovskite-type compound with Ba and Ti, where Ba can be replaced by Ca or Sr, and Ti by Zr, along with La, Mg, and Mn, is used, with specific mole ratios to enhance dielectric characteristics and life characteristics during high temperature tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is thinned to achieve miniaturization and capacity enlargement, then the capacitor size is reduced and capacity is enlarged, but the field intensity applied to each layer increases causing reliability deterioration during voltage application and high temperature load tests
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific amounts of rare-earth oxide (2.0-5.0 molar %) and adjusting the Ba/Ti molar ratio (1.005-1.025) with controlled unreacted BaO content (≤0.7 weight %). This compositional parameter change enables the dielectric layer to maintain high reliability under high field intensity conditions even when thinned, resolving the contradiction between miniaturization and reliability
Solution Approach 2:
The patent creates a composite dielectric ceramic material combining BaTiO3 main components with rare-earth oxide additives (La, Nd, Sm, Dy, or Er) and subcomponents (MnO and oxide glass). This composite material structure provides enhanced dielectric properties and reliability under high field intensity, allowing the dielectric layer to be thinned while maintaining performance
2Volume of moving object
If the dielectric layer is thinned to achieve miniaturization, then the capacitor size is reduced, but the dielectric characteristics deteriorate under high field intensity conditions
Solution Approach 1:
The patent optimizes compositional parameters including rare-earth oxide content (2.0-5.0 molar %), Ba/Ti molar ratio (1.005-1.025), and unreacted BaO content (≤0.7 weight %) to achieve stable dielectric characteristics. These parameter changes enable the thin dielectric layer to maintain composition stability under high field intensity, resolving the contradiction between thinning and dielectric characteristic stability
Data Source
AI summary
A multilayer ceramic capacitor exhibits superior life characteristics in a high temperature load test despite the use of very thin dielectric layers. As a dielectric ceramic constituting a dielectric layer of the multilayer ceramic capacitor, a perovskite-type compound is used and contains Ba and Ti (a portion of Ba can be replaced with at least one of Ca and Sr, and a portion of Ti can be replaced with Zr) as a main component, and including La within the range of 2-6 parts by mole, Mg within the range of 3-5 parts by mole, and Mn within the range of 1.5-3 parts by mole in a case where a total content of Ti and Zr is 100 parts by mole.