Multilayer Ceramic Capacitor Side-Margin Oxide for Gap-Free Insulation
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to gaps between inner and side margin portions, leading to deteriorated insulation resistance and reduced functionality, especially when thicknesses of side margin portions are reduced for downsizing and increased capacitance.
Innovation Solution
Incorporating a crystalline oxide with at least one of Al, Mg, and Si as a secondary phase in the side margin portions, with an aspect ratio between 5 and 20, to reduce gap formation and enhance moisture resistance and withstand voltage, while maintaining a small size and high capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thicknesses of side margin portions are reduced to increase the area of inner electrode layers, then capacitance increases and device size decreases, but gaps develop between inner layer portion and side margin portions due to shrinkage difference, leading to deteriorated insulation resistance
Solution Approach 1:
The patent changes the chemical composition parameters of the side margin portions by incorporating specific metal elements (Al, Mg, Si) in controlled amounts. This compositional parameter change modifies the shrinkage characteristics during firing, enabling the side margin portions to shrink at a rate more consistent with the inner layer portion, thereby preventing gap formation while maintaining reduced thickness for high capacitance and small size
Solution Approach 2:
The patent creates a composite structure by combining the base dielectric material with specific metal elements (Al, Mg, Si) in the side margin portions. This composite material approach allows the side margin portions to have different shrinkage properties than the inner layer portion, compensating for shrinkage differences and preventing gap formation during the firing process while maintaining the desired thin profile
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 solution effectively prevents gap formation between inner and side margin portions, improving moisture resistance and withstand voltage, thus ensuring high reliability and large capacitance in compact multilayer ceramic capacitors.
Implementation Method 1
gaps are prone to develop between the inner layer portion and the side margin portions, or especially between end portions on both sizes of the inner electrode layers and the right and left side margin portions due to a difference in percentage of shrinkage
Implementation Method 2
insulation resistance between the dielectric layers is deteriorated by intrusion of moisture into the aforementioned gaps
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including an inner layer portion defined by alternately laminating a plurality of dielectric layers and a plurality of inner electrode layers, and a pair of side margin portions sandwiching the inner layer portion in a width direction. When viewing a cross-section provided by cutting the multilayer body at a position at a central portion in a length direction and defined by the width direction and a lamination direction, a crystalline oxide including at least one of Al, Mg, and Si is present in the side margin portions as an elongate secondary phase at an aspect ratio equal to or above about 5 and equal to or below about 20.