Multilayer Ceramic Capacitor Uniform Base Metal Diffusion
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Solution Overview
Problem
Existing multilayer ceramic capacitors face a decrease in permittivity due to non-uniform base metal concentration along the stacking direction, leading to capacitance variability and anomalies, as the base metal is not adequately diffused throughout the dielectric layer.
Innovation Solution
A multilayer ceramic capacitor design with a uniform base metal concentration within ±20% of the average across five regions between internal electrodes, combined with an average grain size of 200 nm or less in the dielectric layer, ensures consistent Ni distribution and increased grain boundary diffusion, stabilizing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the base metal is not diffused in the middle portion of the dielectric layer in the stacking direction, then the manufacturing process is simpler, but the concentration of the base metal becomes partially high in the stacking direction, which decreases the permittivity of the dielectric layer
Solution Approach 1:
The patent applies parameter changes by controlling the sintering temperature and atmosphere to achieve uniform base metal concentration distribution throughout the dielectric layer. By optimizing the sintering conditions (temperature, time, and oxygen partial pressure), the base metal diffuses uniformly from the internal electrodes through the entire dielectric layer thickness, preventing localized high concentration regions that would decrease permittivity.
Solution Approach 2:
The patent replaces mechanical mixing or physical distribution methods with thermal diffusion during sintering. Instead of attempting to mechanically distribute the base metal uniformly, the invention uses controlled thermal energy to drive spontaneous diffusion of base metal atoms from the internal electrodes through the dielectric layer, achieving uniform concentration distribution through thermodynamic processes.
2Productivity
If the dielectric layer thickness is reduced and the number of stacked dielectric layers is increased to achieve small-sized large-capacity, then the capacitance increases, but the base metal concentration becomes non-uniform and permittivity decreases
Solution Approach 1:
The patent changes the sintering parameters (temperature, time, atmosphere) to achieve uniform base metal concentration distribution in thin dielectric layers. By optimizing these parameters, the diffusion distance is sufficient even for reduced thickness dielectric layers, ensuring uniform concentration throughout the stacked structure and maintaining high permittivity while achieving small-sized large-capacity.
Solution Approach 2:
The patent addresses the concentration uniformity issue by considering diffusion in multiple dimensions during sintering. The thermal diffusion process operates in three-dimensional space throughout the stacked capacitor structure, ensuring uniform base metal distribution not only within each thin dielectric layer but also across the entire stacked assembly, maintaining permittivity despite increased layer count.
3Ease of manufacture
If the base metal concentration is non-uniform in the stacking direction, then the manufacturing process is simpler, but the capacitance exhibits variability and anomalies
Solution Approach 1:
The patent replaces simple manufacturing processes that result in non-uniform concentration with a controlled thermal diffusion process during sintering. This substitution ensures uniform base metal distribution throughout the dielectric layer, eliminating the capacitance variability and anomalies that arise from concentration non-uniformity, while the overall process remains integrated into the standard manufacturing flow.
4Ease of manufacture
If the grain size in the dielectric layer is not controlled, then the manufacturing process is simpler, but the permittivity of the dielectric layer decreases
Solution Approach 1:
The patent applies parameter changes by controlling the sintering temperature and time to achieve and maintain grain size of 200 nm or less in the dielectric layer. By optimizing these sintering parameters, the grain growth is limited while still achieving complete reaction and uniform base metal concentration distribution, thereby maintaining high permittivity without requiring additional complex grain size control 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 inhibits the decrease in permittivity and stabilizes capacitance, reducing capacitance anomalies and variability among multilayer ceramic capacitors, maintaining capacitance within the normal distribution range.
Implementation Method 1
a concentration distribution of a base metal in a stacking direction in a dielectric layer is uniform
Implementation Method 2
a concentration of the base metal in each of five regions is within ±20% of an average of the concentrations of the base metal in the five regions
Data Source
AI summary
A multilayer ceramic capacitor includes: a pair of external electrodes; a first internal electrode containing a base metal and coupled to one of the external electrodes; a dielectric layer stacked on the first internal electrode and containing a ceramic material and the base metal; and a second internal electrode stacked on the dielectric layer, containing the base metal, and coupled to another one of the external electrodes, wherein a concentration of the base metal in each of five regions, which are equally divided regions of a region between locations 50 nm away from the first and second internal electrodes in a stacking direction between the first and second internal electrodes, is within ±20% of an average of the concentrations of the base metal in the five regions, and an average grain size in the dielectric layer is 200 nm or less.