Multilayer Ceramic Capacitor Boundary Layer Moisture Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors face moisture ingress through gaps between inner electrodes and dielectric layers, leading to deteriorated performance.
Innovation Solution
A multilayer ceramic capacitor design incorporating a boundary layer with Mg and Mn between the outermost inner electrode and dielectric ceramic layer, along with specific proportions and molar ratios of elements like Mn, Mg, and Ni, to prevent moisture entry and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer ceramic capacitor is designed with inner electrodes and dielectric layers to achieve compact size and high capacitance, then the capacitance density and compactness are improved, but gaps between the inner electrodes and dielectric layers create pathways for moisture ingress, deteriorating the reliability
Solution Approach 1:
A boundary layer comprising Mg and Mn is introduced as an intermediary between the outermost inner electrode and the outermost dielectric layer. This boundary layer acts as a moisture barrier, preventing moisture from penetrating into the capacitor through the gap. The boundary layer does not substantially contact the inner electrode, creating a protective interface that blocks moisture ingress pathways while maintaining the overall compact multilayer structure.
2Reliability
If the gap between inner electrodes and dielectric layers is reduced to prevent moisture ingress, then moisture resistance is improved, but manufacturing precision requirements increase due to the need for tighter tolerances in layer alignment
Solution Approach 1:
The boundary layer serves as a mediator that decouples the moisture barrier function from the structural interface between the inner electrode and dielectric layer. By placing the moisture-blocking boundary layer in the gap region without requiring substantial contact with the inner electrode, the design achieves effective moisture protection while maintaining standard manufacturing tolerances for layer alignment.
Solution Approach 2:
The boundary layer is specifically positioned at the outermost regions where moisture ingress is most likely to occur. This localized approach concentrates the moisture protection function at critical interfaces (the outermost dielectric layers and outermost inner electrodes) rather than requiring uniform precision across the entire multilayer structure, thereby reducing overall manufacturing precision requirements.
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic multilayer body including dielectric layers and inner electrodes stacked on top of one another with the dielectric layers interposed between a corresponding pair of the inner electrodes. The dielectric layers each include a perovskite-type compound including Ba and Ti. A boundary layer including Mg and Mn is located at an interface between an outermost inner electrode and an outermost dielectric layer. The outermost inner electrode is located at an outermost position of the inner electrodes in a direction in which the inner electrodes are stacked. The outermost dielectric layer is located outside the outermost inner electrode. A proportion in which the boundary layer is present at the interface is about 69% or more. A continuity of the outermost inner electrode is about 60% or more.