Multilayer Ceramic Capacitor Mo Ground Layer Hydrogen Blocking
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Solution Overview
Problem
Multilayer ceramic capacitors face degradation in insulating resistance due to hydrogen intrusion from external electrodes, which existing technologies have not effectively addressed despite the use of nickel in internal electrode layers.
Innovation Solution
A multilayer ceramic capacitor design with external electrodes featuring a plated layer on a ground layer containing Mo, where the Mo concentration is optimized to suppress hydrogen intrusion, ensuring the formula M≥0.003185×(Ew×Et)−0.5921 is satisfied, and a manufacturing method involving the use of a metal paste with a Mo source to form the external electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ni is added as a metal for suppressing hydrogen adsorption to the internal electrode, then hydrogen adsorption is suppressed, but hydrogen intrusion from external electrodes still degrades insulating resistance
Solution Approach 1:
A ground layer comprising Mo is introduced as an intermediary between the external electrode and the internal electrode. This ground layer acts as a mediator that suppresses hydrogen intrusion from the external electrode into the internal electrode, thereby protecting the dielectric layer from hydrogen-induced degradation while maintaining the beneficial effects of the plated layer structure.
Solution Approach 2:
The external electrode is constructed as a composite structure with a ground layer comprising Mo and a plated layer formed on the ground layer. This composite material approach combines the hydrogen-blocking properties of Mo with the protective plated layer, creating a multi-functional external electrode that effectively prevents hydrogen intrusion while maintaining electrical connectivity.
2Reliability
If a plated layer is formed on the ground layer, then external electrode structure is improved, but hydrogen generation in plating creates intrusion paths
Solution Approach 1:
The plating process, which generates hydrogen as a harmful byproduct, is followed by forming a ground layer comprising Mo that specifically suppresses hydrogen intrusion. The harmful hydrogen generated during plating is converted into a manageable situation by introducing the Mo ground layer that blocks hydrogen paths, thereby transforming the plating process from a harmful operation into an acceptable manufacturing step that provides both structural integrity and hydrogen protection.
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 optimized Mo concentration effectively blocks hydrogen intrusion, preventing adsorption into internal electrode layers and reducing dielectric layer reduction, thereby enhancing the insulating resistance of the multilayer ceramic capacitors.
Implementation Method 1
hydrogen generated in the plating is adsorbed in the internal electrode layer and an insulating resistance of the dielectric layer is degraded by reduction caused by the hydrogen
Implementation Method 2
a plated layer is formed on a ground layer
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer chip in which each of dielectric layers and each of internal electrode layers are alternately stacked and the internal electrode layers are alternately exposed to two end faces; and external electrodes formed on the two end faces; wherein: the external electrodes have a structure in which a plated layer is formed on a ground layer including Mo; and “M≥0.003185×(Ew×Et)−0.5921 is satisfied when “Et” is a height from a bottom one of the internal electrode layers to a top one of the internal electrode layers, “Ew” is a width of the internal electrode layers in a direction in which side faces of the multilayer chip face with each other, and “M” is a Mo concentration (atm %) with respect to a main component ceramic of a total of the multilayer chip and the pair of external electrodes.