Multilayer Ceramic Capacitor Dielectric Composition for DC Bias
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face challenges in ensuring effective capacitance and longevity under high-rated voltages, particularly when dielectric layer thickness is reduced, leading to compromised DC bias properties and reliability.
Innovation Solution
A multilayer ceramic capacitor with dielectric layers composed of (Ba(1-x-y)CaxSry)m(Ti(1-z)Zrz)O3, incorporating rare earth elements, Mg, Mn, V, and Si compounds, and sintered at 1000°C or higher, to enhance DC bias properties and reliability while reducing dielectric layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric layer thickness is reduced to increase capacitance, then the capacitance increases, but the reliability under high rated voltage deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric material by incorporating specific rare earth elements (Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) at controlled concentrations (0.1-5.0 mol%). This compositional parameter change enables the dielectric layer to maintain high reliability under high voltage while allowing for reduced thickness to achieve higher capacitance values.
Solution Approach 2:
The patent creates a composite dielectric material system combining barium titanate base ceramic with multiple additives including rare earth oxides, magnesium compounds, manganese compounds, vanadium compounds, and silicon compounds. This composite structure provides synergistic effects that improve both the electrical properties for high capacitance and the mechanical/chemical stability for high voltage reliability, even at reduced thickness.
2Length of stationary object
If the dielectric constant is increased to reduce dielectric layer thickness, then the dielectric layer thickness can be reduced, but the effective capacity under DC voltage application deteriorates
Solution Approach 1:
The patent optimizes the dielectric constant parameter by controlling the rare earth element content at 0.1-5.0 mol%, which is sufficient to improve DC bias properties without excessively increasing the dielectric constant. This parameter control allows achieving the desired capacitance with thinner layers while maintaining effective capacity under DC voltage.
Solution Approach 2:
The patent applies different functional additives at specific concentrations to achieve localized optimization: rare earth elements for DC bias stability, magnesium and manganese for grain boundary control, and vanadium/silicon for specific property enhancement. This localized quality approach ensures the dielectric layer has the right balance of properties for both thinness and effective capacity.
3Adaptability or versatility
If conventional dielectric materials are used to achieve high dielectric constant, then the dielectric constant increases, but the DC bias properties deteriorate
Solution Approach 1:
The patent develops a composite dielectric material where barium titanate is combined with rare earth oxides (0.1-5.0 mol%), magnesium compounds (0.2-2.5 mol), manganese compounds (0.1-1.0 mol), vanadium compounds (0.05-0.3 mol), and silicon compounds (0.2-5.0 mol). This composite structure achieves high dielectric constant while the rare earth elements specifically improve DC bias properties by stabilizing the dielectric constant under applied voltage.
Solution Approach 2:
The patent changes the chemical composition parameters by introducing rare earth elements at controlled levels (0.1-5.0 mol%), which modifies the dielectric properties to achieve both high dielectric constant and improved DC bias characteristics. The specific concentration range is critical for balancing these two properties.
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 provides excellent DC bias properties and high reliability even with reduced dielectric layer thickness, effectively addressing the limitations of conventional capacitors in maintaining capacitance and longevity under high voltage conditions.
Implementation Method 1
When DC voltage is applied to BaTiO3 or other material exhibiting strong dielectric property, its dielectric constant drops (in a capacitor, the capacitance of the capacitor drops)
Implementation Method 2
sintered at 1000°C or higher
Data Source
AI summary
A multilayer ceramic capacitor (10) has a laminate body (20) constituted by dielectric layers (17) and internal electrode layers (18) stacked alternately. The dielectric layers (17) contain (Ba(1-x-y)CaxSry)m(Ti(1-z)Zrz)O3, where 0.03≤x≤0.16, 0≤y≤0.02, 0<z≤0.02, 0.99≤m≤1.02, as a primary component, and an R oxide (R is a rare earth element) by 1.0 to 4.0 mol in equivalent element, an Mg compound by 0.2 to 2.5 mol in equivalent element, an Mn compound by 0.1 to 1.0 mol in equivalent element, a Zr compound by 0.1 to 2.0 mol in equivalent element, a V compound by 0.05 to 0.3 mol in equivalent element, and an Si compound by 0.2 to 5.0 mol in equivalent element, per 100 mol of the primary component. The multilayer ceramic capacitor can offer excellent DC bias properties and ensure high reliability.