Multilayer Ceramic Capacitor Ground Layer Hydrogen Barrier
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Solution Overview
Problem
Multilayer ceramic capacitors face significant challenges in suppressing insulation resistance (IR) degradation due to hydrogen adsorption near external electrodes, which affects the reliability and humidity resistance of the capacitors.
Innovation Solution
Incorporating a ground layer with a metal or alloy composition including Ni and Cu, and adjusting the Mo concentration to satisfy the relationship M≥−0.00002×EM+0.0012, where EM is the length of the end margin and M is the Mo to B-site element ratio, effectively blocks hydrogen intrusion and enhances the insulating resistance by preventing hydrogen permeation and oxygen defects in the ceramic dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plated layer is formed on a ground layer for external electrodes, then electrical conductivity and electrode performance are improved, but hydrogen is generated during plating and diffuses into the capacitor body causing IR degradation
Solution Approach 1:
The patent introduces a ground layer as an intermediary barrier between the plated layer and the dielectric layer. This ground layer, containing specific metal elements (Ni, Cu, Mo) in controlled concentrations, mediates the hydrogen diffusion path by absorbing or blocking hydrogen atoms before they can reach and degrade the dielectric layer, thus protecting the capacitor while maintaining electrode functionality
Solution Approach 2:
The patent optimizes the chemical composition parameters of the ground layer by controlling the concentrations of metal elements (Ni: 1-10 at%, Cu: 1-10 at%, Mo: 0.1-5 at%) and their ratios to B-site elements in the dielectric layer. By adjusting these compositional parameters, the ground layer's hydrogen barrier effectiveness is enhanced while maintaining electrical conductivity for proper electrode performance
2Object-generated harmful factors
If Ni is added to the internal electrode to suppress hydrogen adsorption, then hydrogen adsorption is reduced, but the cost and manufacturing complexity increase
Solution Approach 1:
The patent extracts the hydrogen suppression function from the internal electrode structure and relocates it to the ground layer. Instead of modifying the internal electrode composition with additional metals like Ni, the ground layer is designed to perform the hydrogen barrier function, simplifying the internal electrode structure while achieving the same protective effect
Solution Approach 2:
The ground layer is designed to serve multiple functions simultaneously: it provides electrical conductivity for electrode performance, acts as a hydrogen barrier to prevent IR degradation, and serves as a structural interface layer. This multi-functionality eliminates the need for separate hydrogen suppression measures in the internal electrode
3Reliability
If the external electrode thickness is increased to secure humidity resistance reliability, then humidity resistance is improved, but the device size and manufacturing complexity increase
Solution Approach 1:
The patent applies local quality enhancement by concentrating the hydrogen barrier and humidity resistance functions in the ground layer region that interfaces with the dielectric. By optimizing the metal element distribution specifically in this critical interface zone (ground layer composition), the local protective quality is enhanced without requiring uniform thickness increase across the entire external electrode structure
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
This approach significantly reduces IR degradation, enhancing the reliability and humidity resistance of multilayer ceramic capacitors by suppressing hydrogen adsorption and diffusion into the internal electrode layers, thereby maintaining stable insulating resistance.
Implementation Method 1
the ground layer includes Mo; and wherein a relationship 'M≥−0.00002×EM+0.0012' is satisfied... effectively blocks hydrogen intrusion and enhances the insulating resistance by preventing hydrogen permeation
Implementation Method 2
hydrogen generated in the plating diffuses into a main body and causes IR (insulation resistance) degradation after being adsorbed near the external electrodes
Implementation Method 3
forming a multilayer chip from the ceramic multilayer structure and ground layers from the metal paste, by firing the ceramic multilayer structure on which the metal paste is coated
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: a relationship “M≥−0.00002×EM+0.0012” is satisfied, when a length of end margins in a direction in which the two end faces face with each other is EM [μm] and a ratio of Mo [atm %] to a B site element [atm %] of a main component ceramic in the end margins is M, wherein the end margin is a region, in which internal electrode layers connected to one of the external electrodes without sandwiching internal electrode layers connected to the other of the external electrode, face with each other, in the multilayer chip.