Multilayer Ceramic Capacitor Oxide Barrier for Moisture Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with moisture penetration through the Ni-Cu alloy layer, leading to deterioration of insulation resistance, especially when increasing capacitance.
Innovation Solution
The implementation of oxide films on the end surfaces of internal electrode layers, specifically at both end portions in the width direction, prevents moisture penetration and diffusion from the base electrode layer to the internal electrode and dielectric layers, thereby maintaining insulation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Cu base electrode layer at the ridge portion is filled with the Ni-Cu alloy layer to increase capacitance, then the effective area of the internal electrode layer is increased, but moisture penetration occurs through the alloy layer to the internal electrode layer or dielectric layer, deteriorating insulation resistance
Solution Approach 1:
The patent applies different properties to different regions of the base electrode layer. Specifically, the ridge portion is designed with a different structure than other areas - it includes an oxide film barrier layer that prevents moisture penetration, while other portions can have the Ni-Cu alloy layer for capacitance enhancement. This local differentiation allows the ridge portion to resist moisture while maintaining overall capacitance.
Solution Approach 2:
The oxide film is introduced as an intermediary barrier between the Ni-Cu alloy layer and the internal electrode layer/dielectric layer. This oxide film layer specifically at the ridge portion acts as a mediator that blocks moisture diffusion paths, preventing the harmful interaction between the moisture-permeable alloy layer and the sensitive internal components.
2Loss of substance
If the thickness of the Cu base electrode layer at the ridge portion is made thin to reduce material usage, then manufacturing cost is reduced, but moisture penetration occurs more easily through the thin layer to the internal electrode layer or dielectric layer
Solution Approach 1:
The patent implements local quality by providing the oxide film barrier specifically at the ridge portion where the base electrode layer is thin. This localized protection ensures that the thinnest and most vulnerable area has enhanced moisture resistance, compensating for the reduced material thickness without increasing overall material usage.
Solution Approach 2:
The base electrode layer is designed as a composite structure combining Cu, Ni-Cu alloy, and oxide film layers. This composite approach allows the thin Cu layer to be reinforced with the moisture-blocking oxide film, achieving both material efficiency and moisture resistance through material composition rather than increased thickness.
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 oxide films effectively reduce moisture penetration and prevent insulation resistance deterioration, ensuring electrical conductivity and capacitance even with increased capacitance.
Implementation Method 1
an oxide film is provided on each of the first end surface-side exposed portion and the second end surface-side exposed portion... the oxide film includes a first oxide film on the first end surface-side exposed portion, and a second oxide film on the second end surface-side exposed portion
Data Source
AI summary
In a multilayer ceramic capacitor, a first internal electrode layer includes a first end surface-side exposed portion exposed to a first end surface side, a second internal electrode layer includes a second end surface-side exposed portion exposed to a second end surface side, and oxide films in the first and second end surface-side exposed portions. The oxide films include first and second oxide films respectively in the first and second end surface-side exposed portions. The first oxide films are provided at both ends in a width direction of the first end surface-side exposed portion, and the second oxide films are provided at both ends in the width direction of the second end surface-side exposed portion.