Multilayer Ceramic Capacitor Dummy Layer Hydrogen Trapping
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Solution Overview
Problem
Multilayer ceramic capacitors experience insulation resistance (IR) degradation due to hydrogen diffusion from plating, which is not sufficiently suppressed by existing technologies.
Innovation Solution
Incorporating a dummy layer made of metal or alloy, including nickel, between the capacity region and the external electrodes' contact area without a ground layer, to trap hydrogen and prevent its diffusion into the internal electrode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plated layer is provided on the ground layer of external electrodes, then electrical conductivity and solderability are improved, but hydrogen is generated during plating and diffuses into the multilayer structure causing IR degradation
Solution Approach 1:
A dummy layer made of nickel or nickel alloy is introduced as an intermediary between the plated layer and the dielectric layers. This dummy layer acts as a hydrogen barrier, preventing hydrogen generated during plating from diffusing into the multilayer structure and causing IR degradation, while allowing the plated layer to maintain its electrical conductivity and solderability functions
Solution Approach 2:
The external electrode structure is segmented into multiple functional layers: the ground layer for electrical connection, the dummy layer for hydrogen barrier function, and the plated layer for conductivity and solderability. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between achieving good electrical properties and preventing hydrogen diffusion
2Object-generated harmful factors
If thermal treatment is applied to release hydrogen from the multilayer structure, then some hydrogen can be removed, but it is difficult to sufficiently suppress IR degradation
Solution Approach 1:
Instead of applying thermal treatment after hydrogen has already diffused into the structure, the dummy layer is provided in advance as a preventive barrier. This preliminary action blocks hydrogen diffusion before it can cause IR degradation, making post-treatment methods unnecessary for achieving sufficient suppression
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 dummy layers effectively trap hydrogen, suppressing its movement towards the internal electrode layers and thereby reducing IR degradation, enhancing the capacitor's insulation resistance.
Implementation Method 1
a dummy layer which is provided between the capacity region and the external electrode and which intersects with a region in which the plated layer contacts the multilayer structure without the 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 each of the internal electrode layers is alternately exposed to two end faces; external electrodes including a ground layer and a plated layer, the ground layer extending from the two end faces to at least one face of four faces of the multilayer chip, the plated layer being provided on the ground layer, a part of the plated layer contacting the at least one face; and a dummy layer that is provided between a capacity region and the at least one face and intersects with a region in which the plated layer contacts the multilayer chip without the ground layer, a main component of the dummy layer being a metal or an alloy including at least Ni.