Dielectric Porcelain Composition for MLCC Oxygen Defect Suppression
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Solution Overview
Problem
Multilayer ceramic capacitors with BaTiO3-based dielectric materials experience degradation of insulation performance over time when fired in a reducing atmosphere due to oxygen defects in the crystal lattice, leading to reduced reliability and high-temperature load lifetime.
Innovation Solution
A dielectric porcelain composition with a perovskite-type compound containing Ti and a volatile element forming a solid solution at the B site, with a specific molar ratio of A-site elements to Ti and Zr, and optional inclusion of Zr, rare earth elements, transition metals, and Si, is used to suppress oxygen defect diffusion by volatilizing the volatile element in a reducing atmosphere during firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BaTiO3-based dielectric porcelain composition is fired in a reducing atmosphere, then the internal electrode material remains unoxidized and good conductivity is maintained, but oxygen defects are caused in the crystal lattice leading to degradation of insulation performance over time
Solution Approach 1:
The patent converts the harmful oxygen defects caused by reducing atmosphere firing into beneficial B-site vacancies by using a volatile element (Ga, In, or Zn) that volatilizes during firing to create controlled vacancies. These vacancies suppress oxygen defect formation and migration, transforming the harmful effect into a protective mechanism that maintains insulation performance.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating a volatile element (Ga, In, or Zn) at the B-site of the perovskite structure with specific molar ratios (0.01-0.20 relative to A-site elements, and 0.97-0.80 for Ti). This compositional parameter change enables controlled volatilization to create vacancies that suppress oxygen defect formation.
2Reliability
If a perovskite compound with A-site rich composition is used, then the dielectric constant and specific resistance are improved, but oxygen defect diffusion is accelerated at high temperatures
Solution Approach 1:
The patent converts the harmful high-temperature oxygen defect diffusion into a beneficial effect by using the volatile element to create B-site vacancies. These vacancies act as traps that suppress oxygen defect migration even at high temperatures, transforming the temperature-induced harm into a controlled protective mechanism.
Solution Approach 2:
The patent creates a composite perovskite structure combining A-site elements (Ba, Sr, Ca), B-site elements (Ti, Zr), and volatile elements (Ga, In, Zn). This composite material approach allows the volatile element to provide vacancy-induced suppression of oxygen defect diffusion while maintaining the high dielectric constant and specific resistance of the A-site rich composition.
3Reliability
If a volatile element is incorporated into the perovskite structure, then oxygen defect diffusion is suppressed through volatilization, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges the dielectric material formation and vacancy creation processes into a single firing step. The volatile element is incorporated during the same firing process that forms the perovskite structure, and its subsequent volatilization automatically creates the protective vacancies without requiring separate processing steps.
Solution Approach 2:
The volatile element performs dual functions: it serves as a structural component during firing and then automatically volatilizes to create the protective vacancies. This self-service mechanism eliminates the need for additional processing steps to create vacancies, as the material itself generates the protective effect during normal manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes insulation performance degradation over time, ensuring high reliability and extended high-temperature load lifetime for multilayer ceramic capacitors even under continuous long-term operation.
Implementation Method 1
volatilizing the volatile element in a reducing atmosphere during firing
Data Source
AI summary
A dielectric porcelain composition having a main component a perovskite compound represented by ABO3, and the perovskite compound at least contains Ti and a volatile element which forms a solid solution at a B site, and may also contain Zr. The dielectric porcelain composition contains the volatile element in an amount larger than 0 part by mol and less than or equal to 0.2 part by mol with respect to 100 parts by mol of a total of the Ti and the Zr, and has a ratio of an A-site element to the total of the Ti and the Zr of 1.00 or more and 1.04 or less as a molar ratio.