Multilayer Ceramic Capacitor Mo Interposing Layer Hydrogen Barrier
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Solution Overview
Problem
Multilayer ceramic capacitors face degradation in insulating resistance due to hydrogen intrusion from external electrodes, which is not effectively suppressed by existing technologies, even with the use of nickel in internal electrode layers.
Innovation Solution
A multilayer ceramic capacitor design featuring a ground layer with a plated structure including Ni and Cu, where a surface interposing substance of Mo is used to block hydrogen intrusion, preventing its adsorption and reduction in the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plated layer is formed on a ground layer in the external electrode, then the electrical conductivity and corrosion resistance are improved, but hydrogen is generated during plating and intrudes into the internal electrode layer, degrading the insulating resistance of the dielectric layer
Solution Approach 1:
An interposing layer containing Mo (molybdenum) is introduced between the ground layer and the plated layer to act as a barrier that prevents hydrogen generated during plating from intruding into the internal electrode layer, while still allowing the plated layer to provide its electrical conductivity and corrosion resistance functions
Solution Approach 2:
The external electrode is designed as a composite structure with multiple layers (plated layer, interposing layer with Mo, and ground layer) where each layer has specific compositional characteristics that collectively prevent hydrogen intrusion while maintaining the required electrical and corrosion properties
2Reliability
If Ni is added to the internal electrode layer to suppress hydrogen adsorption, then the hydrogen adsorption is reduced, but hydrogen still intrudes through the external electrode and degrades the insulating resistance
Solution Approach 1:
The interposing layer with Mo serves as a mediator that blocks hydrogen intrusion at the external electrode interface, complementing the Ni in the internal electrode layer and providing a dual-defense mechanism against hydrogen damage
Solution Approach 2:
The interposing layer is prepared in advance during the electrode formation process to preemptively block hydrogen intrusion paths before hydrogen can reach and damage the internal electrode layer and dielectric interface
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 use of Mo as a surface interposing substance effectively suppresses hydrogen intrusion, maintaining the insulating resistance of the capacitor by blocking hydrogen permeation paths, thereby reducing the incidence of reduced resistance.
Implementation Method 1
at least a part of a surface of the ground layer on a side of the plated layer includes an interposing substance including Mo
Implementation Method 2
the pair of external electrodes have a structure in which a plated layer is formed on a ground layer
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer chip having a parallelepiped shape in which each of a plurality of dielectric layers and each of a plurality of internal electrode layers are alternately stacked and each of the internal electrode layers is alternately exposed to two end faces of the multilayer chip, a main component of the plurality of dielectric layers being a ceramic; and a pair of external electrodes that are formed on the two end faces; wherein: the pair of external electrodes have a structure in which a plated layer is formed on a ground layer; a main component of the ground layer is a metal or an alloy including at least one of Ni and Cu; and at least a part of a surface of the ground layer on a side of the plated layer includes an interposing substance including Mo.