Eu-Valence Dielectric Material for MLCC Reliability Under High Field
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Solution Overview
Problem
Ceramic electronic devices, such as multilayer ceramic capacitors, face reliability issues due to increased electric field loads, despite the addition of rare earth elements like Eu, which can lead to oxygen vacancy degradation and limited lifetime improvement.
Innovation Solution
A dielectric material with a perovskite structure, where the A site includes Ba and the B site includes Ti, with Eu having a valence ratio of +2 valence of 21% or more, is used, and a manufacturing method involving firing and annealing processes under specific conditions to enhance the reliability and lifetime of the dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements like Eu are added to perovskite to improve reliability, then the dielectric material can withstand higher electric field loads, but oxygen vacancy degradation occurs and lifetime improvement is limited
Solution Approach 1:
The patent changes the valence state parameter of Eu from the conventional +3 to a mixed valence state with +2 (21-80%). This parameter change fundamentally alters the mechanism by which Eu interacts with oxygen vacancies, transforming it from a harmful element to a beneficial one that suppresses oxygen vacancy movement and improves both reliability and lifetime simultaneously
2Volume of moving object
If the electric field load per dielectric layer increases to achieve smaller device size, then device miniaturization is achieved, but the reliability of dielectric materials becomes insufficient
Solution Approach 1:
By changing the valence state parameter of Eu to +2 (21-80%), the dielectric material can withstand higher electric field loads without degradation. This enables device miniaturization with increased capacitance density while maintaining or improving reliability, as the modified Eu suppresses oxygen vacancy movement that would otherwise be accelerated by high electric fields
3Reliability
If Eu is added to perovskite to improve dielectric performance, then the material structure is modified, but grain growth occurs that could degrade the structure
Solution Approach 1:
Changing Eu's valence to +2 (21-80%) modifies its interaction with the perovskite lattice, preventing the grain growth that typically occurs with conventional +3 valence Eu. The +2 valence Eu suppresses oxygen vacancy movement and stabilizes the grain structure, maintaining fine-grained morphology while improving dielectric performance
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 approach significantly improves the high-temperature load lifetime and reliability of the dielectric layers by optimizing the valence ratio of Eu, reducing oxygen vacancy movement, and maintaining insulation characteristics, while preventing grain growth that could degrade the structure.
Implementation Method 1
annealing a fired dielectric material at a temperature lower than a temperature of the firing process and at an oxygen partial pressure lower than an oxygen partial pressure of the firing process
Implementation Method 2
annealing a fired multilayer structure at a temperature lower than a temperature of the firing and at an oxygen partial pressure lower than an oxygen partial pressure of the firing
Data Source
AI summary
A dielectric material includes a perovskite as a main phase, an A site of the perovskite including at least Ba, a B site of the perovskite including at least Ti, and Eu having +2 valence and +3 valence. A ratio of +2 valence of Eu is 21% or more.