Dielectric Ceramic Composition for Ni-Electrode MLCCs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The KSr2Nb5O15 ceramic composition, despite providing a high dielectric constant, has insufficient resistivity, leading to unstable operation of monolithic ceramic capacitors at high driving voltages.
Innovation Solution
A dielectric ceramic composition with a tungsten bronze type complex oxide formula (K1−xNax)Sr2Nb5O15, incorporating accessory components such as Y, La, Pr, and Mn, along with other metals, to enhance resistivity, while maintaining a high dielectric constant, and using Ni for internal electrodes to reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If KSr2Nb5O15 ceramic composition is used to achieve high dielectric constant, then the dielectric constant is improved, but the resistivity becomes insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the KSr2Nb5O15 ceramic by introducing controlled amounts of accessory components (R and M) to change the electrical properties. Specifically, R components (e.g., Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) are added at 0.01-10 mol% and M components (e.g., Mn, Ni, Cu, Co, Fe, Zn, Mg, Ca, Sr, Ba) at 0.01-20 mol%, which alters the resistivity parameter while maintaining the high dielectric constant characteristic of the base material.
Solution Approach 2:
The patent creates a composite ceramic material by combining the base KSr2Nb5O15 tungsten bronze structure with multiple accessory components. This composite approach allows the material to inherit the high dielectric constant from the base structure while the added components (particularly M components like Mn, Ni, Cu) provide enhanced resistivity, thus resolving the contradiction between dielectric constant and resistivity.
2Ease of manufacture
If Ni is used for internal electrodes to reduce manufacturing cost, then manufacturing cost is reduced, but the firing atmosphere must be reducing atmosphere which complicates the process
Solution Approach 1:
The patent employs a reducing atmosphere during firing to prevent oxidation of the Ni internal electrodes. The dielectric ceramic composition is designed to be stable in this reducing atmosphere, allowing the use of inexpensive Ni while maintaining electrode integrity. The reducing atmosphere acts as a protective environment that prevents harmful oxidation reactions.
Solution Approach 2:
The patent modifies the firing process parameters by controlling the atmosphere composition (introducing reducing gases like H2 or CO) and temperature profiles. This allows the simultaneous achievement of Ni electrode formation without oxidation and proper sintering of the dielectric ceramic, resolving the conflict between cost reduction and process complexity.
Data Source
AI summary
A dielectric ceramic composition that is used for a monolithic ceramic capacitor, can be cofired with internal electrodes mainly composed of Ni at a temperature of 1200° C. or less, and has a high resistivity is provided. The dielectric ceramic composition is mainly composed of a tungsten bronze type complex oxide having a composition formula of (K1-xNax)Sr2Nb5O15 (wherein 0≦x<0.2) and further contains, as accessory components, 0.05 to 20 molar parts of R (wherein R is at least one selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and 0.05 to 40 molar parts of M (wherein M is at least one selected from the group consisting of Mn, V, Li, Si, Ni, Cr, Co, Fe, Zn, Mg, and Zr) per 100 molar parts of the main component.