Multilayer Ceramic Capacitor Reliability Under High Temperature and Humidity
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability challenges at high temperatures and high electric fields, as well as in high humidity environments, where they are subjected to severe conditions that existing designs struggle to meet.
Innovation Solution
A multilayer ceramic capacitor design featuring dielectric ceramic layers with a perovskite compound containing Ba, Ti, Zr, and a rare earth element, along with Al-containing segregated substances in internal electrodes, which improves reliability by controlling grain diameter and distribution, thereby enhancing performance under high temperature and high electric field conditions and high humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric materials and structures are used, then basic capacitor function is achieved, but reliability deteriorates under high temperature and high electric field conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric layer by incorporating specific amounts of Y2O3 (0.01-0.1 wt%) and Nb2O5 (0.01-0.1 wt%) into the barium titanate-based ceramic system. These compositional modifications alter the material's electrical and thermal properties, enabling it to maintain stability under high temperature and high electric field conditions while improving overall reliability
Solution Approach 2:
The patent creates a composite dielectric material system by combining barium titanate (BaTiO3) with oxide additives (Y2O3 and Nb2O5). This composite structure leverages the high permittivity of BaTiO3 while the oxide additives provide electrical stabilization and defect suppression, resulting in a material that performs reliably under severe operating conditions
2Reliability
If conventional dielectric materials and structures are used, then basic capacitor function is achieved, but reliability deteriorates under high humidity and high electric field conditions
Solution Approach 1:
The patent modifies the dielectric composition by adding Y2O3 and Nb2O5, which change the material's resistance to moisture penetration and chemical stability. These compositional changes create a more robust dielectric that maintains its electrical properties even in high humidity environments combined with high electric fields
Solution Approach 2:
The patent uses small quantities of oxide additives (totaling only 0.02-0.2 wt%) that act as sacrificial elements to prevent more significant degradation of the main dielectric structure. These additives preferentially react with or trap harmful species, protecting the bulk material from humidity-induced degradation
3Volume of moving object
If capacitance is increased for smaller size, then miniaturization is achieved, but reliability under severe conditions deteriorates
Solution Approach 1:
The patent employs a composite dielectric system where barium titanate provides high permittivity for miniaturization while oxide additives ensure reliability. This composite approach allows the capacitor to achieve high capacitance in a small volume without sacrificing performance under severe conditions
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: dielectric thickness, electrode area, and material composition. By changing the compositional parameters to include oxide additives, the material achieves both high permittivity (enabling miniaturization) and enhanced stability (ensuring reliability under severe conditions)
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic laminated body including dielectric ceramic layers and internal electrodes stacked with the dielectric ceramic layers disposed therebetween. The dielectric ceramic layers contain a perovskite compound containing Ba and Ti, Zr, and a rare earth element, and ratios of Zr and the rare earth element to 100 molar parts of Ti are about 0.4 to 2.0 molar parts and about 0.05 to 0.5 molar parts, respectively. The molar ratio of Zr to the rare earth element is about 3.3 to about 8.0, and Al-containing segregated substances are present in about 80% or more of defective portions where continuity of the internal electrodes is interrupted. Dielectric ceramic constituting the dielectric ceramic layers has an average grain diameter of about 230 nm to about 350 nm.