Multilayer Ceramic Capacitor Electrodes With Bi Surface Layer
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Solution Overview
Problem
The thinning and multi-layering of dielectric layers in multilayer ceramic capacitors increase the electric field intensity per unit area, leading to reduced reliability, particularly at high temperatures due to nickel oxidation in the internal electrode layers.
Innovation Solution
Incorporating a surface layer of bismuth (Bi) on the nickel (Ni) metal layers of the internal electrode, suppressing nickel oxidation and enhancing the high-temperature reliability of the multilayer ceramic capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric layer is thinned and multi-layered to increase capacitance and reduce size, then the capacitance increases and size decreases, but the electric field intensity per unit area increases causing nickel oxidation and reliability deterioration
Solution Approach 1:
A surface layer comprising bismuth (Bi) is introduced as an intermediary between the nickel (Ni) metal layer and the dielectric layer. This surface layer acts as a protective mediator that suppresses nickel oxidation during high-temperature operation, thereby maintaining reliability while enabling thin-film dielectric structures for high capacitance
Solution Approach 2:
The internal electrode layer is transformed from a simple nickel metal layer into a composite structure consisting of a nickel base layer combined with a bismuth-containing surface layer. This composite structure provides both the electrical conductivity of nickel and the oxidation resistance of bismuth, resolving the contradiction between thinning and reliability
2Volume of moving object
If the dielectric layer thickness is reduced to enable downsizing, then the capacitor size decreases, but the electric field intensity increases causing nickel oxidation
Solution Approach 1:
The bismuth surface layer serves as a protective intermediary that shields the nickel metal layer from oxidation caused by high electric field intensity. This allows the dielectric layer to be thinned for downsizing while the surface layer prevents the harmful oxidation effect
3Use of energy by moving object
If nickel is used in the internal electrode layer for high conductivity, then electrical conductivity improves, but nickel oxidation occurs at high temperatures reducing reliability
Solution Approach 1:
The internal electrode layer is designed as a composite material combining nickel for high electrical conductivity with a bismuth surface layer for oxidation resistance. This composite structure maintains the electrical performance of nickel while protecting it from high-temperature oxidation that would reduce reliability
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 bismuth surface layer effectively reduces nickel oxidation, thereby improving the high-temperature reliability of the multilayer ceramic capacitor by maintaining electrical conductivity.
Implementation Method 1
the bismuth (Bi) surface layer effectively reduces nickel oxidation, thereby improving the high-temperature reliability of the multilayer ceramic capacitor by maintaining electrical conductivity
Data Source
AI summary
A multilayer ceramic capacitor and a method of manufacturing the same, the multilayer ceramic capacitor including a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on the outside of the capacitor body, wherein the internal electrode layer includes a metal layer including nickel (Ni); and a surface layer disposed on the surface of the metal layer and including bismuth (Bi), and the bismuth (Bi) is included in the surface layer in an amount of about 0.01 to about 5.3 parts by atom based on 100 parts by atom of nickel (Ni) present in the entire internal electrode layer.