Multilayer Ceramic Capacitor Crack Resistance via Floating Electrodes
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Solution Overview
Problem
Multilayer ceramic electronic components are prone to short-circuits due to cracks caused by thermal or flexural stress, especially when cracks run obliquely and intersect effective regions within the ceramic element assembly, leading to potential short-circuits even if the crack does not originate from the edges of extended terminal electrodes.
Innovation Solution
A multilayer ceramic electronic component design featuring a ceramic element assembly with specific internal electrode configurations and effective regions, including floating internal electrodes and inner conductors, where the relationships between electrode lengths and distances are carefully managed to direct cracks away from critical areas, ensuring that even oblique cracks do not cause short-circuits by creating unbalanced stress within the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the opposing distance Z between internal electrodes is reduced to increase capacitance, then the capacitance extraction is improved, but the distance R from extended sections to effective regions is also reduced, making the component more susceptible to short-circuits from oblique cracks
Solution Approach 1:
The patent divides the internal electrode structure into multiple segments: first internal electrodes extending to the first end surface, second internal electrodes extending to the second end surface, and floating internal electrodes suspended within the ceramic element assembly. This segmentation creates multiple effective regions separated by non-effective regions, allowing capacitance to be extracted from multiple locations while distributing the stress and crack propagation paths, thereby preventing a single crack from causing complete failure.
Solution Approach 2:
The floating internal electrodes act as intermediary elements between the first and second internal electrodes. These floating electrodes are positioned to overlap with both sets of internal electrodes, creating additional effective regions for capacitance extraction. The floating electrodes also serve as stress distribution elements that help prevent crack propagation through the critical effective regions, thus improving reliability without sacrificing capacitance.
2Device complexity
If a single effective region is used to simplify the structure, then the device complexity is reduced, but the component becomes more vulnerable to short-circuits from cracks
Solution Approach 1:
The patent divides the capacitance extraction into multiple effective regions created by different electrode combinations: first effective regions between first internal electrodes and floating internal electrodes, and second effective regions between second internal electrodes and floating internal electrodes. This segmentation allows the component to maintain functionality even if one effective region is compromised by a crack, as other effective regions remain intact and continue to provide capacitance.
Solution Approach 2:
The patent applies local quality by creating different types of effective regions with different characteristics. The first and second effective regions are positioned and dimensioned differently, allowing each to contribute to the total capacitance in a unique way. This local differentiation ensures that cracks affecting one region do not necessarily affect others, improving overall reliability while maintaining a relatively simple overall structure.
Data Source
AI summary
A multilayer ceramic capacitor includes first internal electrodes extending to a first end surface of a ceramic element assembly, a plurality of second internal electrodes extending to a second end surface, floating internal electrodes arranged so as to overlap the first and second internal electrodes with ceramic layers disposed therebetween to define first and second effective regions, inner conductors that are elongated from the first end surface beyond a region that overlaps the first effective region in the direction of layering, and a relationship X1<Y1<(L−E) is satisfied where L is the dimension in the longitudinal direction extending from the first end surface to the second end surface, X1 is the longitudinal-direction dimension of each of the first internal electrodes, Y1 is the distance between the first end surface and an end of each of the first internal electrodes, and E is the distance between the second end surface and an end of the second extended section.