Dielectric Ceramic Grain Size Control for Capacitor Lifetime
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Solution Overview
Problem
Existing laminated ceramic capacitors face reliability issues when dielectric layers are reduced in thickness, particularly under high electric field intensities and high-temperature conditions, as they fail to maintain adequate lifetime characteristics.
Innovation Solution
A dielectric ceramic with a composition of (Ba1-x-yCaxRey)(Ti1-zMz)O3, where Re includes rare-earth elements and M includes magnesium, manganese, aluminum, chromium, and zinc, with crystal grains of 20 nm to 150 nm in size, is used to create laminated ceramic capacitors, enhancing their dielectric properties and lifetime characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dielectric layer thickness is reduced to achieve smaller size and higher capacitance, then capacitance increases and size decreases, but reliability and lifetime characteristics deteriorate under high electric field intensity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (x, y, z values) of the dielectric ceramic material and the grain size parameter (20-150 nm range) to optimize the balance between capacitance and reliability. This allows achieving high capacitance with thin dielectric layers while maintaining excellent lifetime characteristics under high electric field conditions.
Solution Approach 2:
The patent uses composite materials by incorporating multiple dopant elements (rare earth elements, magnesium, manganese, aluminum, chromium, zinc) into the barium titanate-based dielectric ceramic system. This composite approach enhances the material's dielectric properties and reliability, enabling thin dielectric layers to withstand high electric field intensities while maintaining high capacitance.
2Length of moving object
If dielectric layer thickness is reduced to achieve smaller size, then size decreases, but electric field intensity increases causing reliability deterioration
Solution Approach 1:
The patent changes the material parameters by optimizing the chemical composition (specific ranges of x, y, z in the formula (Ba1-x-yCaxRey)(Ti1-zMz)O3) and grain size (20-150 nm) to enable ultra-thin dielectric layers to maintain high reliability under increased electric field intensity, thus resolving the contradiction between reduced thickness and maintained reliability.
Solution Approach 2:
The patent applies local quality by creating uniform nanoscale grain structures (20-150 nm) throughout the dielectric layer, which locally enhances the material's ability to withstand electric field stress. This uniform fine-grained structure distributes the electric field more evenly, preventing localized breakdown even in ultra-thin layers.
3Quantity of substance
If dielectric layer thickness is reduced to achieve higher capacitance, then capacitance increases, but electric field intensity increases causing lifetime characteristic deterioration
Solution Approach 1:
The patent employs composite materials with multiple dopants (rare earth elements combined with magnesium, manganese, aluminum, chromium, and zinc) in the dielectric ceramic system. This composite structure enhances both the dielectric constant (increasing capacitance) and the material's stability under high electric field conditions (extending lifetime), thus resolving the contradiction between high capacitance and long lifetime.
Solution Approach 2:
The patent optimizes the compositional parameters (x, y, z values) and grain size parameter of the dielectric ceramic to simultaneously achieve high capacitance and extended lifetime. By controlling these parameters within specific ranges, the material exhibits enhanced dielectric properties and improved resistance to electric field-induced degradation over time.
Data Source
AI summary
Provided is a laminated ceramic capacitor which produces excellent lifetime characteristics in a high-temperature loading test even when dielectric layers are reduced in thickness. The dielectric ceramic contains, as its main constituent, a compound represented by the general formula (Ba1-x-yCaxRey)(Ti1-zMz)O3 (where Re is at least one or more elements selected from among La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and M is at least one or more elements selected from among Mg, Mn, Al, Cr, and Zn), 0≦x≦0.2, 0.002≦y≦0.1, and 0.001≦z≦0.05. This dielectric ceramic has crystal grains of 20 nm or more and 150 nm or less in average grain size.