Multilayer Capacitor Core-Shell Dielectric for High-Temperature Reliability
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Solution Overview
Problem
Existing multilayered capacitors for automotive electric devices face challenges in uniformly adding additives to the dielectric base material, limiting their performance at high temperatures and pressures.
Innovation Solution
A multilayered capacitor design with a core-shell structure in dielectric crystal grains, where the shell includes hafnium (Hf), enhancing the potential barrier and maintaining high dielectric constant and reliability at high temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If various additives are added to the dielectric base material to achieve high reliability and high dielectric constant at high temperature, then the dielectric performance is improved, but the uniformity of additive distribution deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell region contains a higher concentration of hafnium additives compared to the core. This non-uniform distribution is intentional and achieves optimal performance: the shell provides high dielectric constant and reliability at grain boundaries where electrical stress is highest, while the core maintains good processability and sintering characteristics. This resolves the contradiction by making the additive distribution non-uniform in a controlled, beneficial way rather than attempting uniform distribution throughout.
2Strength
If the bandgap of the dielectric is increased to improve withstand voltage characteristics at high temperature, then the potential barrier between core and shell increases, but the dielectric constant may be reduced
Solution Approach 1:
The patent applies local quality by concentrating hafnium in the shell region rather than uniformly distributing it. The shell with higher hafnium content provides the necessary bandgap increase and potential barrier for high withstand voltage characteristics at grain boundaries, while the core maintains composition optimized for high dielectric constant. This spatial separation allows both high strength (withstand voltage) and high reliability (dielectric constant) to coexist.
Solution Approach 2:
The patent uses composite materials by creating a core-shell structure with different compositions. The core consists of dielectric base material with optimal composition for high dielectric constant, while the shell contains the same base material doped with hafnium to increase bandgap and potential barrier. This composite structure allows the capacitor to simultaneously achieve high dielectric constant from the core and high withstand voltage from the shell, resolving the contradiction between these two properties.
Data Source
AI summary
A multilayered capacitor including a capacitor body including a dielectric layer and an internal electrode, and an external electrode on the capacitor body, wherein the dielectric layer includes a plurality of dielectric crystal grains, at least one of the plurality of dielectric crystal grains has a core-shell structure, and the shell includes hafnium (Hf).