Multilayer Ceramic Capacitor Ni Concentration Gradient
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in reducing stress between dielectric and internal electrode layers, leading to crack generation due to differences in contraction percentages, which existing techniques fail to adequately address by not diffusing Ni throughout the dielectric layer in the stacking direction.
Innovation Solution
A multilayer ceramic capacitor design where Ni is distributed across the dielectric layer in five regions, with a higher Ni concentration by 10% or more in the end regions compared to the central region, effectively reducing thermal stress by aligning contraction percentages with the internal electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is thinned to achieve small-sized large-capacity capacitors, then the capacitor size is reduced and capacitance is increased, but stress due to contraction percentage difference generates cracks in the dielectric layer
Solution Approach 1:
The patent applies local quality by creating a non-uniform Ni concentration distribution within the dielectric layer. The Ni concentration is higher at the end regions (closest to internal electrodes) and lower in the central region, with the end regions having Ni concentration greater than the central region by 10% or more. This localized variation in composition allows different parts of the dielectric layer to have different mechanical properties, specifically reducing stress concentration at the interfaces with internal electrodes while maintaining overall layer integrity.
Solution Approach 2:
The patent changes the compositional parameter (Ni concentration) within the dielectric layer to address the stress problem. By adjusting the Ni concentration gradient - specifically making the end regions have Ni concentration greater than the central region by 10% or more - the thermal expansion characteristics are modified locally to match the contraction behavior of internal electrodes, thereby reducing stress and preventing cracks in thinned dielectric layers.
2Ease of manufacture
If Ni is diffused only in the end regions of the dielectric layer, then the manufacturing process is simpler, but stress between the dielectric layer and internal electrode layer is not sufficiently reduced
Solution Approach 1:
The patent implements local quality by concentrating Ni diffusion in the end regions of the dielectric layer (within 50 nm from each internal electrode interface) rather than uniformly throughout the entire layer. This localized diffusion approach simplifies the manufacturing process compared to uniform diffusion, while still achieving sufficient stress reduction at the critical interface regions where stress concentration occurs.
Solution Approach 2:
The patent applies partial action by diffusing Ni only in the end regions (within 50 nm from interfaces) rather than throughout the entire dielectric layer thickness. This partial diffusion is sufficient to reduce interfacial stress where it matters most, while avoiding the complexity and potential degradation effects of full-layer diffusion. The end regions constitute a small portion of the total layer but provide the critical stress relief function.
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 design significantly reduces thermal stress and inhibits crack generation in the dielectric layer, ensuring the reliability and durability of the capacitor by maintaining a consistent Ni concentration gradient across the dielectric layer.
Implementation Method 1
Ni is contained in five regions, and a Ni concentration in at least one of end regions located closest to the first internal electrode and the second internal electrode among the five regions is greater than a Ni concentration in a central region of the five regions
Data Source
AI summary
A multilayer ceramic capacitor includes: a pair of external electrodes; a first internal electrode that is coupled to one of the pair of external electrodes; a dielectric layer that is stacked on the first internal electrode and contains BaTiO3 and Ni; and a second internal electrode that is stacked on the dielectric layer, contains Ni, and is coupled to another one of the pair of external electrodes, wherein Ni is contained in five regions, which are equally divided region 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, and a Ni concentration in at least one of end regions located closest to the first internal electrode and the second internal electrode among the five regions is greater than a Ni concentration in a central region of the five regions by 10% or more.