BaTiO3 Multilayer Ceramic Capacitor with Mo-Mn Doping for Thin Dielectrics
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving both increased capacitance and extended service life while maintaining reliability, particularly when dielectric layers are thinner than 0.8 μm, as they are prone to shorting and leak current issues.
Innovation Solution
The use of ceramic grains with BaTiO3 as the primary component, incorporating Mo, Mn, rare earth elements, and at least one of V and W, with an average valence number of Mo between 4.50 and 5.50, adjusts the dielectric layer composition to enhance service life and suppress leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of dielectric layers is reduced to increase capacitance, then the capacitance increases, but the service life decreases and reliability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric layer by controlling the content of donor elements (Mo: 0.01-0.05 wt%, W: 0.01-0.05 wt%) and acceptor elements (Mn: 0.05-0.20 wt%, Ni: 0.05-0.20 wt%, Co: 0.05-0.20 wt%) to optimize the balance between capacitance and service life. This compositional parameter adjustment allows the dielectric layer to maintain high capacitance while improving resistance to voltage stress and extending service life.
Solution Approach 2:
The patent creates a composite dielectric material system based on barium titanate (BaTiO3) with multiple dopant elements. The combination of donor elements (Mo, W) and acceptor elements (Mn, Ni, Co) forms a complex composite structure that synergistically improves both capacitance performance and reliability, allowing the material to withstand higher voltages without breakdown even at reduced thickness.
2Quantity of substance
If the thickness of dielectric layers is reduced to increase capacitance, then the capacitance increases, but the leak current increases
Solution Approach 1:
The patent adjusts the chemical composition parameters by precisely controlling the ratios of donor and acceptor elements to reduce leak current. The donor elements (Mo, W) increase capacitance while acceptor elements (Mn, Ni, Co) compensate for excessive carrier concentration, thereby reducing leak current. This parameter optimization enables thin dielectric layers to maintain low leak current despite increased capacitance.
3Reliability
If donor elements such as Mo and W are added to improve service life, then the service life increases, but the leak current increases
Solution Approach 1:
The patent merges the functions of donor elements (Mo, W) and acceptor elements (Mn, Ni, Co) within the same dielectric layer. The donor elements provide high capacitance and improved service life, while the acceptor elements simultaneously suppress leak current by compensating for excessive carrier concentration. This functional merging resolves the contradiction between service life improvement and leak current reduction.
Solution Approach 2:
The patent changes the compositional parameters by establishing specific content ranges for both donor and acceptor elements. By controlling Mo at 0.01-0.05 wt%, W at 0.01-0.05 wt%, and acceptor elements at 0.05-0.20 wt%, the patent optimizes the balance between service life enhancement and leak current suppression, achieving both goals simultaneously.
4Quantity of substance
If the dielectric layer thickness is reduced to 0.8 μm or less, then the capacitance increases, but shorting occurs between internal electrodes
Solution Approach 1:
The patent develops a composite dielectric material with enhanced insulation properties through multi-element doping. The combination of BaTiO3 with donor elements (Mo, W) and acceptor elements (Mn, Ni, Co) creates a material structure that maintains high insulation resistance even at thicknesses of 0.8 μm or less, preventing shorting between internal electrodes while achieving high capacitance.
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
This composition allows for increased capacitance while ensuring excellent service life and reduced leak current, even at dielectric layer thicknesses of 0.8 μm or less, by optimizing the valence number of Mo within the specified range.
Implementation Method 1
The capacitance of a multilayer ceramic capacitor is directly proportional to the dielectric constant of the constitutional material of the dielectric layers
Data Source
AI summary
A multilayer ceramic capacitor includes a laminate constituted by internal electrode layers of different polarities alternately layered via dielectric layers, wherein the multilayer ceramic capacitor is such that the dielectric layers contain ceramic grains whose primary component is BaTiO3, the ceramic grains contain Mo, Mn, rare earth R, and at least one of V and W, and the average valence number of Mo in the ceramic grains is 4.50 to 5.50. The multilayer ceramic capacitor can offer excellent service life characteristics and sufficiently suppress leak current even when the thickness of the dielectric layer is 0.8 μm or less.