Multilayer Ceramic Varistor with Glass Barrier

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Solution Overview

Problem

Existing ceramic multilayer components with varistor functions face degradation when integrated with other ceramics, limiting their use in portable devices due to sensitivity to composition diffusion and inability to maintain electrical properties during sintering.

Innovation Solution

A monolithic ceramic multilayer component is developed by co-sintering a varistor ceramic with a dielectric ceramic, using a dielectric material composed of Zn3TaO8, Zn2TaO6, and Bi2Zn2/3Ta4/3O7, with controlled ion substitutions, to minimize interdiffusion and maintain critical varistor properties like low reverse current and pulse stability, integrated with metallizations for additional component functions like capacitance and inductance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If varistor ceramic is co-sintered with other ceramics to form monolithic multilayer component, then integration of multiple component functions is achieved and space is saved, but the electrical properties of the varistor degrade impermissibly due to composition diffusion

Engineering Contradiction:

Improveintegration of component functionsVSAvoidelectrical properties of varistor

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A barrier layer composed of a glass ceramic with specific composition (SiO2: 30-70 wt%, Al2O3: 5-20 wt%, B2O3: 5-20 wt%, with optional additions of P2O5, TiO2, ZrO2, ZnO, Bi2O3, PbO in controlled amounts) is introduced between the varistor ceramic and other ceramics. This intermediary layer prevents harmful composition diffusion while allowing controlled thermal expansion matching, enabling co-sintering without impermissible degradation of varistor electrical properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The barrier layer utilizes a composite glass ceramic material system combining multiple oxides (SiO2, Al2O3, B2O3) with controlled proportions to achieve simultaneous properties: low warpage during sintering, appropriate thermal expansion coefficient matching with varistor ceramic, and effective diffusion barrier characteristics. This composite material approach resolves the contradiction by providing a multifunctional interface layer.

Inventive Principle:

Principle #40Composite materials

2Productivity

If varistor ceramic is co-sintered with other ceramics, then manufacturing efficiency is improved and production is simplified, but warpage occurs during sintering process

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidwarpage during sintering

Core Design Contradiction:

ProductivityVSShape

Solution Approach 1:

The glass ceramic barrier layer is formulated with specific compositional parameters (high SiO2 content 30-70 wt%, controlled Al2O3 5-20 wt%, B2O3 5-20 wt%) that fundamentally change the thermal and mechanical properties during sintering. These parameter changes result in low warpage behavior while maintaining diffusion barrier functionality, enabling successful co-sintering of multilayer components.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If reverse current of varistor is reduced to maintain functionality in portable devices, then battery discharge time is extended, but protection capability against ESD and EMI is compromised

Engineering Contradiction:

Improvebattery discharge timeVSAvoidprotection capability against ESD and EMI

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The barrier layer acts as a sacrificial or consumable element that absorbs diffusion effects during sintering, protecting the varistor's electrical properties. By accepting the presence of the additional layer and its associated cost/complexity, the varistor maintains its low reverse current characteristics and protection capability without compromise.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 enables the production of space- and cost-saving components with preserved varistor functionality, allowing for effective ESD and EMI protection in portable devices by maintaining electrical stability and integrating diverse component functions without significant degradation.

Implementation Method 1

using a dielectric material composed of Zn3TaO8, Zn2TaO6, and Bi2Zn2/3Ta4/3O7, with controlled ion substitutions, to minimize interdiffusion and maintain critical varistor properties

Methodology Applied

Scientific EffectIon substitution: Ion Exchange

Implementation Method 2

A monolithic ceramic multilayer component is developed by co-sintering a varistor ceramic with a dielectric ceramic

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8970324B2Multilayer component and production method

Publication Date: 2015.03.03 TDK ELECTRONICS AG

AI summary

A multilayer component includes a dielectric ceramic material that can be co-sintered with a varistor ceramic to form a monolithic multilayer component according to the invention. The multilayer component therefore includes a layer of a varistor ceramic and another layer of a dielectric. Both layers can be arranged directly adjacent to one another in the multilayer component. In the multilayer component, metallizations are arranged on or between the ceramic layers. The metallizations are structured to form conductor sections and metallized areas. The metallizations form together with the ceramic layers alongside a varistor at least one further component selected from at least one of the component functions.