Multilayer Ceramic Capacitor Base Metal Diffusion Control
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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.
Innovation Solution
A multilayer ceramic capacitor design with a uniform base metal concentration within ±20% of the average across five regions between internal electrodes, using a ceramic material mainly composed of barium titanate and controlling the Mg to Ti atomic concentration ratio to facilitate even diffusion of the base metal, ensuring stable capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base metal is diffused into 3 to 30% of the distance between internal electrodes to improve temperature characteristic of capacitance, then temperature characteristic is improved, but base metal concentration becomes non-uniform in the stacking direction causing permittivity decrease
Solution Approach 1:
The patent applies local quality by controlling base metal diffusion to be concentrated at specific locations (within 50 nm from internal electrode surfaces) rather than uniformly distributed. This localized diffusion approach allows temperature characteristic improvement at the electrode-dielectric interface while maintaining uniform concentration in the bulk dielectric layer, thus resolving the contradiction between temperature stability and concentration uniformity.
Solution Approach 2:
The patent changes the diffusion parameter distribution by limiting base metal diffusion depth to within 50 nm from the internal electrode surfaces, creating a non-uniform spatial distribution pattern. This parameter control ensures that the diffusion concentration ratio between different regions remains within ±20%, improving temperature characteristics without causing significant permittivity degradation.
2Productivity
If dielectric layers are thinned and number of stacked dielectric layers is increased to achieve small-sized large-capacity capacitors, then capacitance and size requirements are met, but manufacturing precision and concentration uniformity become more difficult to maintain
Solution Approach 1:
By concentrating base metal diffusion within 50 nm from internal electrode surfaces, the patent creates a localized modification that is less sensitive to variations in overall dielectric layer thickness. This local quality approach allows thin dielectric layers to be used for high capacitance density while maintaining controlled base metal concentration uniformity across the stacking direction.
Solution Approach 2:
The patent effectively segments the dielectric layer into two regions: a surface region within 50 nm of internal electrodes where base metal diffusion is concentrated, and a bulk region where concentration remains uniform. This segmentation allows independent optimization of each region's properties, enabling thin dielectric layers with maintained concentration uniformity.
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 stabilizes capacitance and reduces capacitance anomalies by maintaining uniform Ni concentration across the dielectric layers, enhancing the reliability and consistency of multilayer ceramic capacitors.
Implementation Method 1
a base metal is not diffused in the middle portion of the dielectric layer in the stacking direction
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 the base metal and a ceramic material mainly composed of barium titanate; 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 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 atomic concentration ratio of Mg to Ti is 0 or greater and less than 0.002 in the dielectric layer.