Multilayer Ceramic Capacitor Void Distribution for Moisture Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors manufactured using hydrothermally synthesized dielectric powders suffer from reduced moisture resistance due to intragranular voids in the ceramic dielectrics, particularly in the outer-layer and side margin portions, which also affect denseness.
Innovation Solution
Control the intragranular void densities in the inner-layer, outer-layer, and side margin portions of the multilayer ceramic capacitor such that Nouter<Ninner and Nside<Ninner, ensuring the outer-layer and side margin portions have fewer intragranular voids than the inner-layer portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrothermally synthesized dielectric powders are used to manufacture multilayer ceramic capacitors, then the dielectric layers can be made thinner and capacitance increased, but intragranular voids are created in the ceramic dielectrics which reduce moisture resistance
Solution Approach 1:
The patent applies local quality by differentiating the intragranular void density requirements across different regions of the capacitor. The inner-layer portion is allowed to have higher intragranular void density (providing higher capacitance per unit volume), while the outer-layer and side margin portions are restricted to lower intragranular void density (providing better moisture resistance). This regional differentiation resolves the contradiction by optimizing each region for its primary function.
Solution Approach 2:
The patent changes the parameter of intragranular void density differently across regions. By controlling the hydrothermal synthesis conditions and sintering parameters, the patent achieves higher void density in the inner-layer (improving capacitance) while maintaining lower void density in the outer-layer and side margins (preserving moisture resistance). This parameter optimization resolves the technical contradiction.
2Ease of manufacture
If hydrothermally synthesized dielectric powders are used, then manufacturing cost is reduced and fine powders with uniform particle size can be manufactured, but intragranular voids remain in the finished capacitor affecting reliability
Solution Approach 1:
The patent applies local quality by specifying different intragranular void density requirements for different regions. The inner-layer can utilize the full benefits of hydrothermal synthesis including cost efficiency and fine particle uniformity, while the outer-layer and side margins are controlled to have lower void density to ensure reliability. This regional approach allows cost-effective manufacturing without sacrificing overall product reliability.
3Quantity of substance
If intragranular voids are present in the outer-layer and side margin portions, then moisture resistance is reduced, but using hydrothermal synthesis provides benefits of reduced dielectric layer thickness and increased capacitance
Solution Approach 1:
The patent applies local quality by creating a gradient in intragranular void density across the capacitor structure. The inner-layer portion has higher void density optimized for capacitance, while the outer-layer and side margin portions have lower void density optimized for moisture resistance. This spatial differentiation of material properties resolves the contradiction between maximizing capacitance and minimizing moisture penetration.
Solution Approach 2:
The patent converts the potential harm of intragranular voids into a benefit by strategically distributing them. Instead of eliminating all voids (which would require abandoning hydrothermal synthesis), the patent allows voids in the inner-layer (where they contribute to capacitance) while restricting them in the outer-layer and side margins (where they would cause moisture penetration). This transforms the harmful aspect into a controlled feature that serves the overall 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
This configuration enhances the moisture resistance of the multilayer ceramic capacitors while maintaining the benefits of hydrothermal synthesis, including reduced thickness and increased capacitance.
Implementation Method 1
the hydrothermal method (hydrothermal synthesis) is a method in which a high-temperature and high-pressure aqueous solution is used to synthesize an inorganic powder
Implementation Method 2
the resulting reaction product is subjected to heat treatment to give a BaTiO3 powder. The OH groups included in the hydroxides leave the raw materials during the heat treatment, but as a result of this, voids are created inside the particles of the dielectric powder
Data Source
AI summary
A multilayer ceramic capacitor includes an inner-layer portion, first and second outer-layer portions, and first and second side margin portions, and outer electrodes on the first and second end surfaces. Each of ceramic dielectrics of the inner-layer portion, the first and second outer-layer portions, and the first and second side margin portions includes multiple dielectric particles with a void therein. An intragranular void density in the ceramic dielectric in the inner-layer portion (Ninner), intragranular void densities in the ceramic dielectrics in the first outer-layer portion and the second outer-layer portion (Nouter), and intragranular void densities in the ceramic dielectrics in the first side margin portion and the second side margin portion (Nside) satisfy Nouter<Ninner and Nside<Ninner.