Tall Multilayer Ceramic Capacitor Margins to Preserve Capacitance
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Solution Overview
Problem
Existing techniques for manufacturing multilayer ceramic capacitors face challenges in maintaining high capacitance while preventing short circuits, as additive elements in the ceramic protective layer diffuse into the dielectric layer, reducing relative permittivity and promoting oxidation of internal electrodes.
Innovation Solution
The multilayer ceramic capacitor design features a ceramic body with a multilayer body and margin portions, where the grain growth inhibiting elements are concentrated in the margin portions, reducing their diffusion into the multilayer body and maintaining a large capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grain growth inhibiting elements (Mg, Mn, rare earth elements) are added to the ceramic protective layer, then short circuit between internal electrodes is inhibited, but the elements diffuse into the dielectric layer causing decreased relative permittivity and oxidation of internal electrodes, leading to decreased capacitance
Solution Approach 1:
The patent applies local quality by creating a margin portion with higher concentration of grain growth inhibiting elements only at specific locations (margin portions covering side surfaces) rather than uniformly throughout the entire ceramic protective layer. This localized high concentration prevents short circuits at the sides where grain growth is most problematic, while the lower concentration in the main body minimizes diffusion into the dielectric layer and preserves capacitance.
2Quantity of substance
If the number of stacked dielectric layers is increased to increase capacitance, then the capacitance of the multilayer ceramic capacitor increases, but the contact area between dielectric layers and ceramic protective layer increases, making diffusion of additive elements more likely and causing further capacitance decrease
Solution Approach 1:
The patent concentrates grain growth inhibiting elements in margin portions that cover only the side surfaces of the multilayer body, not the top and bottom surfaces where dielectric layers are stacked. This localized approach prevents harmful diffusion at side surfaces while minimizing contact area between additive elements and dielectric layers in the stacking direction, thus allowing increased number of stacked layers for higher capacitance without proportionally increasing diffusion harm.
3Quantity of substance
If a tall multilayer ceramic capacitor structure is used (dimension in first direction ≥ 1.5 times dimension in second direction), then the capacitance can be increased, but the contact area between margin portions and multilayer body increases, potentially increasing diffusion of grain growth inhibiting elements
Solution Approach 1:
The patent employs asymmetry in the tall multilayer ceramic capacitor structure by making the dimension in the first direction (height) significantly larger than the dimension in the second direction (width), with a ratio of 1.5 or more. The margin portions are configured to cover the side surfaces in the second direction, creating an asymmetric distribution where the majority of the capacitor volume (and capacitance) is in the tall first direction, while the margin portions with grain growth inhibiting elements are concentrated in the narrower second direction, minimizing their contact area with the multilayer body despite the overall tall structure.
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 design effectively inhibits short circuits and ensures a large capacitance in tall multilayer ceramic capacitors by minimizing the diffusion of grain growth inhibiting elements, while also reducing manufacturing costs due to a smaller volume of margin portions.
Implementation Method 1
these additive elements diffuse into the dielectric layer
Data Source
AI summary
A multilayer ceramic capacitor, which has a dimension in a first axis direction equal to or greater than 1.5 times a dimension in a second axis direction orthogonal to the first axis direction and is to be mounted on a mounting surface perpendicular to the first axis direction, includes a ceramic body having main surfaces perpendicular to the first axis, side surfaces perpendicular to the second axis, an end surface perpendicular to a third axis orthogonal to the first and second axes, a multilayer body having internal electrodes that are stacked in the second axis direction and led out to a connection end on the end surface, and margin portions covering the multilayer body from respective sides in the first axis direction, and having a higher concentration of a grain growth inhibiting element than the multilayer body, and an external electrode covering the end surface.