Multilayer Ceramic Capacitor Electrode Openings for Crack Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors are susceptible to cracks and deteriorating withstand voltage characteristics due to the reverse piezoelectric (or electrostriction) phenomenon caused by voltage application, which affects their reliability.
Innovation Solution
The capacitors are designed with a structure that includes groups of first openings in the internal electrodes, which are continuously open in the stacking direction, reducing the electric field and internal stress, and are distributed to minimize the overall reverse piezoelectric phenomenon, thereby enhancing robustness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ferroelectric material (barium titanate) is used in the multilayer ceramic capacitor, then high capacitance is achieved, but internal stress and cracks occur due to reverse piezoelectric phenomenon under voltage application
Solution Approach 1:
The internal electrodes are segmented into multiple groups (first, second, third internal electrodes) with different connection configurations. The first internal electrodes connect to one external electrode, the second internal electrodes connect to the other external electrode, and the third internal electrodes are not connected to external electrodes. This segmentation distributes the electric field and reduces concentrated internal stress, preventing cracks while maintaining high capacitance.
Solution Approach 2:
Different regions of the capacitor have different electrode configurations tailored to local stress conditions. The first and second internal electrodes are connected to external electrodes to provide conduction paths, while the third internal electrodes are left unconnected to act as stress-relief elements in regions prone to high internal stress. This local differentiation optimizes both capacitance and reliability.
2Ease of operation
If voltage is applied to the multilayer ceramic capacitor, then electrical function is achieved, but reverse piezoelectric phenomenon causes internal stress and deteriorates reliability
Solution Approach 1:
The internal electrodes are divided into multiple groups with different connection configurations. The first internal electrodes connect to one external electrode, the second internal electrodes connect to the other external electrode, and the third internal electrodes are not connected to external electrodes. This segmentation distributes the electric field and reduces concentrated internal stress, preventing cracks while maintaining electrical function.
Solution Approach 2:
The capacitor utilizes a ferroelectric material composition with specific ratios of barium titanate (40-70 wt%), lead zirconate titanate (10-30 wt%), and lead magnesium niobate (10-30 wt%). This compositional parameter change optimizes the material's electrical properties while reducing the severity of the reverse piezoelectric effect, allowing electrical function with improved robustness against internal stress.
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 proposed design effectively reduces the reverse piezoelectric phenomenon, minimizing cracks and improving the capacitors' reliability under voltage application, ensuring high voltage withstand and reduced delamination.
Implementation Method 1
a body including a capacitance region in which a plurality of first internal electrodes and a plurality of second internal electrodes are alternately stacked and overlap with one another in a first direction with a dielectric layer interposed therebetween
Data Source
AI summary
A multilayer ceramic capacitor includes a body including a capacitance region in which a plurality of first internal electrodes and a plurality of second internal electrodes are alternately stacked in a first direction with a dielectric layer interposed therebetween, and first and second external electrodes disposed on the body and spaced apart from each other to be connected to the plurality of first internal electrodes and the plurality of second internal electrodes, respectively, wherein the capacitance region includes one or more groups of first openings. The first openings in each group overlap in the first direction and are continuously open in two or more internal electrodes of the plurality of first and second internal electrodes, and a number of internal electrodes included in each group is less than a total number of the plurality of first internal electrodes and the plurality of second internal electrodes.