Multilayer Ceramic Capacitor Uniform Donor Distribution
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Solution Overview
Problem
Multilayer ceramic capacitors with dielectric layers thinner than 0.8 μm face reduced service life and reliability due to fluctuating distribution of donor elements like Mo, Ta, and W, leading to oxygen defects and compromised bias characteristics.
Innovation Solution
A multilayer ceramic capacitor design with dielectric layers containing ceramic grains of Ba, Ti, and donor elements Mo, Ta, or W, where the concentration distribution of these elements is maintained within ±5% across the grain, enhancing service life and bias characteristics by uniform distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the dielectric layer is reduced to increase the number of layers and capacitance, then the capacitance increases, but the voltage applied per unit thickness increases which shortens the service life of the dielectric layer
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric layer by adding donor elements (Mo, Ta, W) to the barium titanate-based ceramic material. This compositional modification enables the dielectric layer to maintain higher service life even when thickness is reduced and voltage per unit thickness is increased, as these donor elements improve the electrical stability and breakdown resistance of the material.
Solution Approach 2:
The patent uses a composite ceramic material consisting of barium titanate as the base dielectric with donor elements (Mo, Ta, W) added as compositional modifiers. This composite approach combines the high dielectric constant of barium titanate with the improved electrical stability provided by the donor elements, allowing thin dielectric layers to achieve both high capacitance and long service life.
2Duration of action of stationary object
If donor elements are added to improve service life, then the service life increases, but the distribution of these elements becomes non-uniform causing oxygen defects and reduced reliability
Solution Approach 1:
The patent precisely controls the concentration parameter of donor elements, specifying that Mo, Ta, and W should be present at 0.01-0.1 atomic% each. This parameter control ensures uniform distribution throughout the ceramic grains while preventing excessive concentration that would cause oxygen defects and reliability issues.
Solution Approach 2:
The patent achieves uniform local quality of donor element distribution throughout the ceramic grains. By ensuring that Mo, Ta, and W are evenly dispersed at the specified low concentrations (0.01-0.1 atomic% each), the patent eliminates local variations that would create oxygen defects, thereby maintaining both improved service life and high reliability.
Data Source
AI summary
A multilayer ceramic capacitor has a laminate including dielectric layers laminated alternately with internal electrode layers of different polarities, wherein the dielectric layer contains ceramic grains having Ba, Ti, and X (wherein X represents at least one type of element selected from the group consisting of Mo, Ta, Nb, and W) and a variation in the concentration distribution of X above in the ceramic grain is within ±5%. The multilayer ceramic capacitor can offer excellent service life characteristics even when the thickness of the dielectric layer is 0.8 μm or less, as well as excellent bias characteristics.