Multilayer Ceramic Capacitor Electrode Stack for Ni Adhesion Control
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Solution Overview
Problem
Existing multilayer ceramic capacitor manufacturing techniques face issues with adhesion between Ni plating layers, leading to potential mechanical strength reduction and hydrogen diffusion, which affects insulation resistance and reliability.
Innovation Solution
A multilayer ceramic electronic component design with a five-layer external electrode structure, including a base film, first Ni film, metal film with lower ionization tendency, second Ni film with higher hydrogen concentration, and a surface layer film, subjected to heat treatment in a weakly oxidizing or reducing atmosphere, to enhance adhesion and reduce hydrogen diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment is performed after forming the first Ni film, then adhesion between the Ni film and subsequent layers is improved, but the Ni film surface oxidizes and adhesion deteriorates
Solution Approach 1:
A metal film containing a metal with lower ionization tendency than Ni (such as Cu, Ag, Au, Pd, or Pt) is inserted between the first Ni film and the second Ni film. This intermediary metal film prevents oxidation of the first Ni film surface during heat treatment while still allowing the second Ni film to form with high adhesion to the underlying structure, thus resolving the contradiction between improving adhesion through heat treatment and preventing surface oxidation.
2Reliability
If a protective oxide layer is formed on the external electrode body, then corrosion resistance is improved, but adhesion between the protective layer and Ni plating layer decreases
Solution Approach 1:
The metal film with lower ionization tendency serves as an intermediary layer between the protective oxide layer and the Ni plating layers. This intermediary metal film maintains good adhesion to both the oxide layer and the Ni films, preventing the adhesion deterioration that would otherwise occur due to the oxide layer's poor bonding characteristics with Ni.
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 solution improves adhesion between electrode layers, reduces hydrogen diffusion, and maintains solder wettability, enhancing the reliability and insulation resistance of the ceramic capacitor.
Implementation Method 1
a metal film that is formed on the first Ni film and contains a metal having a lower ionization tendency than Ni, as a main component
Implementation Method 2
by performing heat treatment after forming the metal film
Implementation Method 3
a second Ni film formed on the metal film
Implementation Method 4
since the plating efficiency is improved when the second Ni film is formed on the surface of the metal film on which a decrease in conductivity due to oxidation is unlikely to occur, the generation amount of hydrogen can be kept small. Therefore, it is possible to prevent deterioration in reliability due to diffusion of hydrogen into the ceramic body
Data Source
AI summary
A multilayer ceramic electronic component includes a ceramic body that has internal electrodes stacked in a direction of a first axis, and end surfaces perpendicular to a second axis orthogonal to the first axis, the internal electrodes being alternately led out to the end surfaces, and external electrodes covering the end surfaces of the ceramic body, wherein each of the external electrodes includes a base film formed on a corresponding one of the end surfaces and connected to the plurality of internal electrodes, a first Ni film formed on the base film, a metal film that is formed on the first Ni film and contains a metal having a lower ionization tendency than Ni, as a main component, a second Ni film formed on the metal film and having a higher hydrogen concentration than the first Ni film, and a surface layer film formed on the second Ni film.