Laminated Ceramic Capacitor High Field Reliability
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Solution Overview
Problem
Laminated ceramic capacitors face challenges in reducing size while increasing capacitance, leading to higher electric field intensities that can result in localized electric field concentration and deficient lifetime characteristics due to decreased crystal grains in thinner dielectric layers.
Innovation Solution
A laminated ceramic capacitor with dielectric ceramic layers composed of a perovskite-type compound containing Ba, Ca, Ti, Mg, R (where R is selected from specific rare-earth elements), Zr, and optional Mn, V, and Si, with specific elemental ratios, and a production method involving powder preparation, mixing, and firing to maintain crystal grain size and enhance dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dielectric ceramic layers are reduced in thickness to achieve smaller size, then the capacitance per unit area increases, but the electric field intensity increases and causes local concentration leading to deficient lifetime characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific amounts of Mg (0.01-0.09 parts by mol), R (2.5-8.4 parts by mol), and Zr (0.05-3.0 parts by mol) with respect to 100 parts by mol of Ti. This composition modification allows the ceramic to maintain adequate crystal grain size and uniform electric field distribution even when layer thickness is reduced to 1 μm or less, thereby improving lifetime characteristics while achieving smaller capacitor size
Solution Approach 2:
The patent creates a composite dielectric ceramic material by combining multiple elements (Ba, Ca, Ti, Mg, R, Zr) in specific ratios. This composite material structure, where R represents rare-earth elements and the elements are distributed in specific locations (Ca at crystal grain centers, Mg and Zr at boundaries), enables simultaneous achievement of small size and high reliability by controlling both crystal grain growth and electric field distribution
2Quantity of substance
If dielectric ceramic layers are reduced in thickness to increase capacitance density, then the number of crystal grains per layer decreases causing local electric field concentration, but increasing layer thickness reduces capacitance
Solution Approach 1:
The patent applies local quality by positioning specific elements at specific locations within the crystal structure: Ca is positioned at the centers of crystal grains, while Mg and Zr are positioned at the boundaries. This spatial distribution creates local regions with different properties that work together to maintain uniform electric field distribution across the entire dielectric layer, preventing local concentration even when the number of grains is reduced
Solution Approach 2:
The patent modifies the compositional parameters by adding specific amounts of Mg (0.01-0.09 parts by mol), R (2.5-8.4 parts by mol), and Zr (0.05-3.0 parts by mol) with respect to 100 parts by mol of Ti. These parameter changes control the crystal grain size and number, enabling adequate grain count per layer to distribute electric field uniformly while maintaining high capacitance density through optimized layer thickness
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 achieves a high dielectric constant with minimal crystal grain size increase, improving lifetime characteristics and enabling small-sized, high-capacitance capacitors with enhanced reliability under high-temperature loading.
Implementation Method 1
a main constituent, a perovskite-type compound including Ba, Ca, and Ti, and further containing Mg, R (R is at least one selected from Y, La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), and Zr
Implementation Method 2
dielectric ceramic layers including crystal grains and crystal grain boundaries
Data Source
AI summary
A laminated ceramic capacitor having high electrostatic capacitance and excellent lifetime characteristics, even when in a high electric field intensity employs a dielectric ceramic including crystal grains and crystal grain boundaries which contains, as its main constituent, a perovskite-type compound including Ba, Ca, and Ti, and further contains Mg, R (Y, La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and/or Yb), and Zr, such that when the laminated body is dissolved, the contents in terms of parts by mol are Ca: 3 to 15 parts by mol, Mg: 0.01 to 0.09 parts by mol, R: 2.5 to 8.4 parts by mol, and Zr: 0.05 to 3.0 parts by mol with respect to 100 parts by mol of Ti, and there is Ca at least at the centers of the crystal grains.