Core-Shell Dielectric Composition for High DC Bias Stability
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Solution Overview
Problem
Existing dielectric compositions for laminated ceramic capacitors face challenges in maintaining high dielectric constant and resistivity when subjected to high DC bias and elevated temperatures, particularly at high voltages and ambient temperatures, due to polarization reversal and reduced reliability.
Innovation Solution
A dielectric composition with a perovskite crystal structure, featuring a core-shell structure where the Bi content in the core portion is at least 1.2 times that in the shell portion, and a specific molar ratio of Bi to Sr, along with the inclusion of auxiliary components like La, Ce, and Zn, enhances the dielectric constant and resistivity while improving high-temperature load lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high DC bias voltage is applied to increase the operating voltage range, then the dielectric constant decreases due to polarization reversal, but the capacitor needs to maintain high dielectric constant for high capacity
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the center region contains high-Bi particles for maintaining dielectric constant under DC bias, while the peripheral region contains low-Bi particles for other functional properties. This spatial differentiation allows the capacitor to simultaneously achieve high operating voltage range and stable dielectric constant.
2Volume of moving object
If miniaturization is pursued to increase circuit density, then the capacitor size decreases, but maintaining high capacity becomes more difficult
Solution Approach 1:
The patent uses composite materials by combining two types of particles with different Bi contents and sizes in a specific ratio (60-80 wt% high-Bi particles, 20-40 wt% low-Bi particles). This composite structure enables the miniaturized capacitor to maintain high capacity through the synergistic effect of the two particle types, achieving high dielectric constant and high resistivity in a compact form.
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 composition achieves a high dielectric constant of 800 or greater and a DC bias resistivity of 1×10^12 Ωcm or greater, with a high-temperature load lifespan of 20 hours or more, even under high DC voltage, effectively addressing the limitations of existing materials.
Implementation Method 1
particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti... a high dielectric constant of 800 or greater
Implementation Method 2
the content of Bi in the core portion is at least 1.2 times the content of Bi in the shell portion... effectively addressing the limitations of existing materials
Implementation Method 3
a DC bias resistivity of 1×10^12 Ωcm or greater... even under high DC voltage
Data Source
AI summary
A dielectric composition, a dielectric element, an electronic component and a multi-layer electronic component are disclosed. In an embodiment the dielectric composition includes particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti, wherein at least some of the particles have a core-shell structure including a core portion and a shell portion and wherein the content of Bi present in the core portion is at least 1.2 times the content of Bi present in the shell portion.