Dielectric Composition for High DC Bias Stability

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Solution Overview

Problem

Conventional dielectric compositions used in medium- and high-voltage capacitors experience a reduction in dielectric constant and capacitance when a high DC bias is applied, particularly in laminated ceramic capacitors with thin layers, due to their design assumptions based on low DC biases.

Innovation Solution

A dielectric composition with a main component of (Bi a Na b Sr c ) (Zn d Ti 1 - d ) O 3, where a, b, c, and d are within specific ranges (0.09≤a≤0.58, 0.09≤b≤0.42, 0.05≤c≤0.84, 0<d≤0.08, and 0.95≤a+b+c≤1.05), achieving a high dielectric constant of 900 or greater when a DC bias of at least 8 V/µm is applied.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional dielectric compositions are used, then the dielectric element can be manufactured with standard materials, but the dielectric constant and capacitance are reduced when high DC bias is applied

Engineering Contradiction:
Improvedielectric constant under high DC biasVSAvoidperformance under varying DC bias conditions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the chemical composition parameters of the dielectric material by incorporating specific ratios of Bi-Zn-Ti-O and Ba-Ti-O systems with controlled doping elements (Mg, Mn, Ga, Nb) to maintain high dielectric constant under high DC bias conditions. The compositional formula (1) with specific ranges for a, b, c, d, e, f, g parameters enables the material to withstand high electric fields while preserving capacitance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite dielectric system combining Bi-Zn-Ti-O and Ba-Ti-O ceramic systems with multiple dopant elements. This composite approach integrates the high dielectric constant of Bi-Zn-Ti-O with the stability of Ba-Ti-O, while dopants like MgO and MnO provide grain boundary control and electrical stability under high DC bias, achieving synergistic performance.

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the dielectric layer thickness is reduced for miniaturization, then the electronic component size is reduced, but the dielectric constant and capacitance decrease under high DC bias

Engineering Contradiction:
Improvecomponent sizeVSAvoidcapacitance under high DC bias
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent modifies the material parameters at the micro-scale to compensate for reduced thickness. By optimizing the compositional formula with specific dopant concentrations and Bi/Zn/Ti ratios, the material achieves enhanced electrical properties that maintain high capacitance even in thin-film configurations under high DC bias conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite Bi-Zn-Ti-O/Ba-Ti-O system with controlled dopant distribution provides superior electrical properties in thin layers. The synergistic combination maintains high dielectric constant and breakdown strength even when the dielectric layer is miniaturized, enabling small-sized capacitors to retain high capacitance under high DC bias.

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If lead-free materials are used, then the environmental friendliness is improved, but achieving high dielectric constant under high DC bias becomes more difficult

Engineering Contradiction:
Improveenvironmental impactVSAvoiddielectric constant under high DC bias
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent achieves lead-free high-performance dielectric by precisely controlling the compositional parameters of Bi-Zn-Ti-O and Ba-Ti-O systems. The specific ranges of dopant concentrations (Mg: 0.001-0.06, Mn: 0.001-0.06, Ga: 0.001-0.06, Nb: 0.001-0.06) and the Bi/Zn/Ti ratio optimization enable the material to achieve dielectric constant ≥900 under 8 V/μm DC bias without any lead content.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent successfully creates a lead-free composite dielectric system combining Bi-Zn-Ti-O and Ba-Ti-O ceramics. This composite approach replaces traditional lead-based PZT or PLZT materials while achieving superior or comparable performance. The multiple dopant elements work synergistically to provide both environmental compatibility and high dielectric performance under high DC bias conditions.

Inventive Principle:
Principle #40Composite materials

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 maintains a high dielectric constant and capacitance under high DC bias, suitable for medium- and high-voltage applications, and is environmentally friendly as it does not contain lead, making it suitable for capacitors with high DC bias requirements.

Implementation Method 1

the dielectric composition has a relatively large dielectric constant when a DC bias of 5 V/μm is applied

Methodology Applied
Scientific EffectDielectric permittivity: Dielectric Permittivity

Data Source

PatentEP3097064B1Dielectric composition, dielectric element, electronic component and laminated electronic component
Publication Date: 2018.02.28 TDK ELECTRONICS AG
  • EP3097064B1 patent drawingFigure 1~2
  • EP3097064B1 patent drawingFigure 3

AI summary

[Problem] The problem addressed lies in providing a dielectric composition having a relatively high dielectric constant of 900 or greater when a DC bias of at least 8 V/ym is applied, and also in providing a dielectric element employing said dielectric composition, an electronic component, and a laminated electronic component. [Solution] A dielectric composition in which the composition of the main component is in accordance with the following formula (1) : (BiaNabSrc) (ZndTi1_d)03 (1) [where a, b, c and d satisfy the following: 0.09≤a≤0.58, 0.09≤b≤0.42, 0.05≤c≤0.84, 0&lt;d≤0.08, and 0.95≤a+b+c≤1.05 ].