Multilayer Ceramic Capacitor Cover Structure Against Moisture Infiltration
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Solution Overview
Problem
Multilayer ceramic capacitors face reduced moisture resistance reliability due to moisture infiltration through the boundaries between side margin portions and external layer portions, which compromises their performance.
Innovation Solution
Incorporating inorganic cover regions made of materials like Si, Ti, or Zr on the outer surfaces of the multilayer body to span the boundaries between side margin portions and external layer portions, thereby preventing moisture infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If side margins are made thin to increase internal electrode area, then capacitance increases and size is reduced, but moisture infiltration through boundaries increases
Solution Approach 1:
A side margin portion made of dielectric ceramic material is introduced as an intermediary component between the internal layer portion and external layer portions. This side margin acts as a protective barrier that prevents moisture from infiltrating through the boundaries, while allowing the side margins to be kept thin to maintain high capacitance and compact size.
Solution Approach 2:
The multilayer body is constructed as a composite structure with different functional layers: internal layer portion (dielectric ceramic + internal electrodes), side margin portion (dielectric ceramic without electrodes), and external layer portions (with external electrodes). This composite structure allows each layer to perform its specific function while working together to achieve both high capacitance and moisture resistance.
2Strength
If side margin portions are added to ensure insulation, then insulation property improves, but moisture infiltration through boundaries increases
Solution Approach 1:
The side margin portion serves as an intermediary structure that simultaneously provides insulation between internal electrodes and acts as a moisture barrier. By positioning it at the boundary between internal and external layers, it fulfills both insulation and moisture protection functions.
3Reliability
If inorganic cover regions are added to prevent moisture infiltration, then moisture resistance reliability improves, but device complexity increases
Solution Approach 1:
The side margin portion is merged with the dielectric ceramic layers during the same stacking and sintering process, rather than being added as a separate component. This integration approach provides moisture protection functionality while avoiding additional manufacturing steps and structural complexity.
Solution Approach 2:
The side margin portion performs multiple functions simultaneously: it provides insulation between internal electrodes, acts as a moisture barrier at the boundaries, and maintains the structural integrity of the multilayer body. This multi-functionality reduces the need for additional protective components.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body and external electrodes. The multilayer body includes an internal layer portion, a first side margin portion and a second side margin portion on both sides of the internal layer portion in a width direction, and a pair of external layer portions on both sides of the internal layer portion in a lamination direction to be positioned between the side margin portions. The multilayer ceramic capacitor includes first and second cover regions including an inorganic material and located on outer surfaces of the multilayer body to each span boundaries between the first or second side margin portion and the external layer portions. End surfaces of the multilayer ceramic capacitor each include an uncovered section that is not covered by the cover region, and are each connected to the external electrode at the uncovered section.