Multi-Layer Ceramic Electrode Plating for Hydrogen Suppression
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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 issues due to instability in the Ni plating layer and adhesion problems after heat treatment.
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 effective hydrogen suppression and solder bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed at high temperature to remove hydrogen from the Ni plating layer, then hydrogen diffusion into the ceramic body is suppressed, but the Ni plating layer becomes oxidized and adhesion deteriorates
Solution Approach 1:
The Ni plating layer is divided into two distinct layers: a first Ni plating layer subjected to heat treatment for hydrogen removal, and a second Ni plating layer formed after heat treatment to provide oxidation protection and ensure adhesion. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
The first Ni plating layer is formed and subjected to heat treatment in advance, before the second Ni plating layer is formed. This preliminary action removes hydrogen from the ceramic body to prevent insulation resistance degradation, while the subsequent formation of the second Ni plating layer restores surface stability and adhesion properties.
2Reliability
If oxidation treatment is performed on the external electrode main body to form a protective layer, then corrosion resistance is improved, but adhesion between the protective layer and Ni plating layer is reduced
Solution Approach 1:
The Ni plating layer is segmented into two layers with different functions: the first Ni plating layer provides the bonding interface with the oxidized protective layer, while the second Ni plating layer provides the final surface for adhesion and soldering. This segmentation resolves the adhesion problem by ensuring that the oxidized surface is not directly exposed.
Solution Approach 2:
The first Ni plating layer acts as an intermediary between the oxidized protective layer and the second Ni plating layer. It provides a stable bonding interface that adheres well to the oxidized surface, while the second Ni plating layer provides the final adhesion surface, thus mediating the adhesion issue caused by oxidation.
3Reliability
If multiple plating layers are formed to suppress hydrogen diffusion, then insulation resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The formation of the first and second Ni plating layers, along with the heat treatment process, is integrated into a unified manufacturing sequence that can be performed in a single production line. The heat treatment is combined with the plating process, and the entire sequence is optimized to minimize the number of separate manufacturing steps, thus reducing overall complexity while maintaining the hydrogen suppression functionality.
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, stabilizes the Ni plating layer, and ensures reliable solder bonding, thereby improving the insulation resistance and adhesion of the multi-layer ceramic electronic components.
Implementation Method 1
the hydrogen in the external electrodes is diffused into a ceramic body
Implementation Method 2
heat treatment is performed at a temperature equal to or higher than a temperature at which the first nickel film is recrystallized
Implementation Method 3
forming a first nickel film on the base film by an electrolytic plating method
Implementation Method 4
the surface of the Ni plating layer subjected to the heat treatment is oxidized
Data Source
AI summary
A multi-layer ceramic electronic component includes: a ceramic body including internal electrodes laminated and drawn to an end face of the ceramic body; and an external electrode including: a base film disposed on the end face of the ceramic body 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, wherein the base film is in contact with the internal electrodes, or the first nickel film is thicker than the second nickel film.