Ceramic Capacitor Pore Control for Voltage Resistance
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Solution Overview
Problem
Ceramic capacitors face a trade-off between increasing voltage resistance and maintaining capacity, as series internal electrode structures reduce capacity and effective cross-sectional area, leading to potential breakdowns due to piezoelectric extension and crack formation.
Innovation Solution
Incorporating pores within ceramic grains in the dielectric layer with a controlled area ratio of 0.03% to 0.20% to suppress piezoelectric distortion and crack occurrence, while using a combination of ceramic powders formed by hydrothermal and other synthesis methods to optimize voltage resistance and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of internal electrodes connected in series is increased to improve voltage resistance, then breakdown voltage increases, but effective cross section area decreases and capacity is reduced
Solution Approach 1:
The patent introduces pores inside ceramic grains with a controlled area ratio of 0.01% to 0.50% to suppress piezoelectric distortion and prevent crack formation. This porous structure allows the capacitor to withstand higher voltages without breakdown while maintaining adequate capacity, resolving the trade-off between voltage resistance and capacity.
Solution Approach 2:
The patent uses a composite ceramic system comprising barium titanate and calcium zirconate in specific proportions (barium titanate: 70-95 vol%, calcium zirconate: 5-30 vol%). This composite material composition enhances both the dielectric properties for capacity and the mechanical strength for voltage resistance, simultaneously addressing both contradictory requirements.
2Reliability
If series pattern of internal electrodes is used to reduce applied voltage between capacitors, then breakdown voltage increases, but capacity is reduced
Solution Approach 1:
The patent modifies the physical and chemical parameters of the ceramic material by controlling pore formation through specific synthesis methods (hydrothermal synthesis combined with solid-phase synthesis) and optimizing firing conditions. These parameter changes enable the material to achieve higher breakdown voltage while maintaining capacity through enhanced piezoelectric distortion suppression.
Solution Approach 2:
The patent creates localized pores within ceramic grains rather than uniformly throughout the structure. This local quality approach allows piezoelectric distortion to be suppressed at critical stress points where cracks would form, while the overall capacitor structure maintains its capacity through the series-connected internal electrode pattern.
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 approach effectively enhances voltage resistance while minimizing capacity reduction, achieving a balance between electrostatic capacity and breakdown voltage by adjusting the pore ratio and synthesis methods for the ceramic powders.
Implementation Method 1
forming a green sheet by using ceramic slurry including a first ceramic powder formed by a hydrothermal synthesis method and a second ceramic powder formed by a method other than the hydrothermal synthesis method
Data Source
AI summary
A ceramic capacitor includes: a dielectric layer of which a main component is a ceramic grain, wherein one or more pores are formed inside of the ceramic grains; and wherein an area ratio of the one or more pores with respect to a cross section of the ceramic grain is 0.03% to 0.20%, in a cross section of the dielectric layer.