Multilayer Ceramic Component Electrodes for Hydrogen-Resistant Ni Plating
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Solution Overview
Problem
The production of multi-layer ceramic capacitors is hindered by hydrogen occlusion in external electrodes, leading to reduced insulation resistance and solder wettability due to inadequate adhesion and stability of plating films during the plating process.
Innovation Solution
A method involving the formation of a base film on a ceramic body, followed by a first nickel film through electrolytic plating, heat treatment in a weakly reducing atmosphere to release hydrogen, and subsequent formation of a second nickel film, which enhances adhesion and stability, ensuring better solder bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an Ni plating layer is formed after oxidation treatment of the external electrode main body, then the protective layer is formed, but the adhesion between the protective layer and the Ni plating layer is reduced
Solution Approach 1:
A Pd plating layer is introduced as an intermediary between the oxidized Cu protective layer and the Ni plating layer. The Pd layer serves as a mediator that maintains good adhesion with both layers, preventing direct contact between the oxidized Cu surface and Ni that would cause poor adhesion.
Solution Approach 2:
The external electrode is constructed as a composite multi-layer structure consisting of Cu base film, Pd plating layer, and Ni plating layer. This composite structure combines the advantages of each material: Cu provides conductivity and cost-effectiveness, Pd provides adhesion and oxidation resistance, and Ni provides protective functionality.
2Object-generated harmful factors
If heat treatment is performed on the Ni plating layer, then hydrogen is released, but the surface of the Ni plating layer is oxidized and becomes unstable
Solution Approach 1:
Heat treatment is performed on the Pd plating layer before forming the Ni plating layer. This preliminary action releases hydrogen from the Pd layer while the Pd surface is still in a favorable state, preventing subsequent oxidation of the Ni layer that would occur if heat treatment were performed after Ni plating.
Solution Approach 2:
The heat treatment process is segmented and performed at different stages: first on the Pd layer before Ni plating, and potentially again after Ni plating. This segmentation allows hydrogen removal from different layers at optimal times, preventing surface oxidation of Ni while maintaining hydrogen release benefits.
3Ease of manufacture
If Sn plating layer is formed directly on oxidized Ni surface, then the plating process is simplified, but the adhesion of the Sn plating layer is reduced and solder wettability is reduced
Solution Approach 1:
The Pd plating layer serves as an intermediary that prevents direct contact between the oxidized Ni surface and the Sn plating layer. This intermediary layer maintains surface stability and provides a favorable substrate for Sn plating, ensuring good adhesion and solder wettability without requiring additional surface treatment steps.
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 effectively suppresses hydrogen diffusion into the ceramic body, maintains solder wettability, and ensures strong adhesion of plating films, thereby preventing insulation failures and ensuring reliable bonding during mounting.
Implementation Method 1
performing, after forming the first nickel film, heat treatment in a weakly reducing atmosphere at a temperature equal to or higher than a temperature at which the first nickel film is recrystallized
Implementation Method 2
the first nickel film subjected to the heat treatment is recrystallized and provided with a configuration to suppress the hydrogen from diffusing
Implementation Method 3
forming a first nickel film on the base film by an electrolytic plating method
Implementation Method 4
the hydrogen taken in the first nickel film or the like is released to the outside
Data Source
AI summary
A multi-layer ceramic electronic component includes: a ceramic body including internal electrodes laminated and drawn to a surface of the ceramic body; and an external electrode including: a base film disposed on the surface of the ceramic body, connected to the internal electrodes, and formed from an electrically conductive material, a first nickel film disposed on and in contact with the base film in a thickness direction of the base film, and a second nickel film disposed on the first nickel film in a thickness direction of the first nickel film.