BaTiO3 Dielectric Composition for X8R MLCC Reliability
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Solution Overview
Problem
Existing multilayer ceramic capacitors using barium titanate-based ferroelectric materials face challenges in achieving guaranteed X8R temperature characteristics and reliability, particularly in high temperature applications due to limitations in temperature coefficient of capacitance (TCC) and the formation of pyrochlore phases which affect reliability.
Innovation Solution
A dielectric ceramic composition is developed with a barium titanate-based base material and minor components, including pyrochlore phases of specific rare-earth elements, which are adjusted to achieve X8R temperature characteristics and improved TCC, while maintaining reliability by controlling the ratio of pyrochlore phase to BaTiO3 and optimizing the content of elements like Mg and CaZrO3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If barium titanate-based ferroelectric materials are used to achieve high capacitance, then dielectric constant is improved, but temperature characteristics and reliability deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of barium titanate (BaTiO3) as the base material combined with specific minor components including rare earth elements (Y, Dy, Ho, Sm, Gd, Er, La, Ce, Nd, Tb, or Pr) and other oxides. This composite approach allows achieving both high capacitance through BaTiO3's high dielectric constant and improved temperature characteristics through the synergistic effects of the minor components that suppress pyrochlore phase formation and stabilize the crystal structure across temperature ranges.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the composition ratios and sintering conditions. The minor components are added in specific amounts (typically 0.1-5.0 wt% of rare earth oxides) to modify the phase composition and suppress harmful pyrochlore phase formation. The sintering temperature and atmosphere parameters are also optimized to achieve the desired phase composition and density while maintaining X8R temperature characteristics.
2Quantity of substance
If barium titanate-based materials are used to achieve high dielectric constant, then capacitance is improved, but pyrochlore phase formation increases which worsens reliability
Solution Approach 1:
The patent converts the potentially harmful effect of rare earth element additions into a beneficial outcome. While rare earth oxides can form pyrochlore phases which are generally harmful, the patent uses specific rare earth elements in controlled amounts that actually suppress pyrochlore formation and stabilize the perovskite structure. The rare earth elements act as dopants that modify the crystal lattice and prevent the formation of harmful secondary phases, turning what could be a harmful impurity into a beneficial stabilizer.
Solution Approach 2:
The patent employs parameter changes by optimizing the concentration of rare earth elements and other minor components to specific ranges. By controlling the amount of rare earth oxides (0.1-5.0 wt%) and adjusting sintering parameters (temperature, atmosphere, time), the patent achieves a phase composition where the perovskite phase is dominant and pyrochlore phase formation is suppressed below detectable levels, thus eliminating the harmful effect while maintaining high dielectric constant.
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 dielectric ceramic composition and resulting multilayer ceramic capacitors exhibit satisfactory X8R temperature characteristics and improved high-temperature withstand voltage, ensuring reliable performance by finely tuning the pyrochlore phase content and element ratios.
Implementation Method 1
a dielectric ceramic composition including: a major component (a barium titanate-based base material); and a minor component, wherein in an XRD analysis of a sintered body obtained by sintering the dielectric ceramic composition
Data Source
AI summary
There is provided a dielectric ceramic composition including: a major component (a barium titanate-based base material); and a minor component, wherein in an XRD analysis of a sintered body obtained by sintering the dielectric ceramic composition, when a (110) peak of BaTiO3 is set as 1.00, a ratio of a peak of pyrochlore (RE2Ti2O7) at about 30.5 degrees with respect to the (110) peak of BaTiO3 satisfies 0.02 or less, where RE is at least one of Y, Dy, Ho, Sm, Gd, Er, La, Ce, Nd, Tb, and Pr.