Multilayer ceramic capacitor
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face issues with cracking due to over-sintering of metal paste, leading to reduced moisture resistance and increased equivalent series resistance (ESR), particularly when using Ni-Cu alloys for inner electrodes.
Innovation Solution
The capacitors are designed with outer electrodes comprising a Cu-based underlying electrode and a Ni plating layer, where the Ni concentration in specific surface regions is controlled to be lower than in other regions, ensuring a balanced distribution that enhances moisture resistance and reduces cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sintering conditions are relaxed to reduce over-sintering of the metal paste, then cracking is reduced, but insufficient sintering of the metal paste increases porosity in the outer electrodes, leading to deterioration in moisture resistance
Solution Approach 1:
The invention applies local quality by creating a non-uniform Ni concentration distribution within the underlying conductor film. The first region (near the dielectric layer) has a higher Ni concentration (0.5-2.0 at%) compared to the second region (0.1-0.5 at%), allowing different local zones to fulfill different functions: the high-Ni region prevents cracking at the critical interface, while the low-Ni region maintains moisture resistance at the outer surface.
Solution Approach 2:
The invention changes the concentration parameter of Ni within the underlying conductor film to resolve the contradiction. By controlling the Ni concentration to vary spatially (higher near the dielectric interface, lower at the outer surface), the material properties are optimized for both crack resistance and moisture resistance simultaneously, rather than using a uniform composition.
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 design provides improved moisture resistance and resistance to cracking, maintaining excellent bending strength and insulation resistance, even under high humidity and stress conditions.
Implementation Method 1
when the metal and glass components are uniformly distributed in the underlying conductor film, stress generated during firing becomes uniform throughout the underlying conductor film, making it possible to prevent cracking in the multilayer body
Implementation Method 2
in the step of firing metal paste for the underlying conductor film including an alloy of Cu and Ni and a glass component
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including first and second surfaces facing each other in a height direction, third and fourth surfaces facing each other in a first direction, and fifth and sixth surfaces facing each other in a second direction, a first underlying electrode on the third, first, second, fifth, and sixth surfaces, and a second underlying electrode on the fourth, first, second, fifth, and sixth surfaces. The first underlying electrode includes a first-surface inside region on the first surface and extending about 1 μm or less from the first surface in the height direction, and a Ni concentration of the first-surface inside region is lower than that of an inside region on the third surface.