Multilayer Ceramic Capacitor Ni-Free Outer Electrode Design
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Solution Overview
Problem
Multilayer ceramic capacitors with minimized regions other than the active region experience decreased environmental resistance and shortened mean time to failure due to degradation of outermost inner electrodes during firing.
Innovation Solution
A multilayer ceramic capacitor design with outermost inner electrode layers thicker than inside layers, featuring a Ni-free region within 0.9 μm from the outer layer and a Ni-containing region beyond, reducing thickness variations and enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the regions other than the active region are minimized to achieve smaller size and greater capacitance, then the capacitance increases and size decreases, but the environmental resistance decreases and the mean time to failure shortens
Solution Approach 1:
The patent applies local quality by creating a Ni-free region specifically in the outer layer portions adjacent to the outermost inner electrode layers, while maintaining Ni-containing regions in other areas. This localized compositional differentiation protects the vulnerable outermost electrodes from oxidation during firing without compromising the overall capacitance achieved through minimized non-active regions.
Solution Approach 2:
The Ni-free region acts as an intermediary protective layer between the outermost inner electrode layers and the external environment. By eliminating Ni in this specific zone, the patent prevents harmful oxidation reactions that would otherwise occur during high-temperature firing, thereby protecting the electrode integrity while maintaining the compact design.
2Reliability
If the outermost inner electrode layers are made thicker to improve thermal stability, then the mean time to failure increases, but the manufacturing precision requirements increase due to thickness control
Solution Approach 1:
The patent implements local quality by making only the outermost inner electrode layers thicker compared to the inner electrode layers. This localized thickness increase provides enhanced thermal stability and oxidation resistance where it is most needed (at the exposed surfaces), while maintaining standard thickness for internal layers, thus balancing reliability improvement with manufacturing feasibility.
Solution Approach 2:
The patent applies parameter changes by modifying the thickness parameter of the outermost inner electrode layers specifically. By increasing the thickness of these outermost layers to be greater than the inner electrode layers, the patent enhances thermal stability and protects against degradation during firing, while the controlled nature of this parameter change maintains manufacturing precision.
3Volume of moving object
If the inner electrode layers are made thinner to achieve smaller size, then the size decreases, but the outermost inner electrodes are more likely to degrade during firing
Solution Approach 1:
The patent applies local quality by creating a Ni-free region specifically in the outer layer portions adjacent to the outermost inner electrode layers. This localized compositional modification provides enhanced protection to the vulnerable outermost electrodes from oxidation during high-temperature firing, compensating for their reduced thickness while maintaining the overall compact size of the capacitor.
Solution Approach 2:
The Ni-free region serves as an intermediary protective barrier between the thinned outermost inner electrode layers and the oxidizing atmosphere during firing. By eliminating Ni in this specific zone, the patent prevents harmful reactions that would otherwise cause degradation of the thinner electrodes, thereby maintaining reliability despite reduced dimensions.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including an inner layer portion in which multiple inner electrode layers and multiple inner dielectric layers are stacked alternately and two outer layer portions located at the surfaces on two sides of the inner layer portion in the stacking direction, with one outer layer portion on each side, and two outer electrodes located at end surfaces of the multilayer body, which are the surfaces on two sides in the length direction, with one outer electrode at each end surface. The inner electrode layers include outermost inner electrode layers, which are the closest to each of the outer layer portions, and an inside inner electrode layer, which is an inner electrode layer other than the outermost inner electrode layers.