Multilayer Ceramic Capacitor Structure With Sn Gradient Insulation
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Solution Overview
Problem
The degradation of insulation characteristics and reduced lifetime of multilayer ceramic electronic devices due to metal diffusion from internal electrode layers into dielectric layers during firing, which also leads to a trade-off between improved insulation and reduced electrostatic capacity due to the sintering and spheroidizing effects of Sn in the dielectric layers.
Innovation Solution
A ceramic electronic device with a multilayer structure where dielectric layers with varying Sn concentrations are stacked, with lower Sn concentration at the outermost ends and higher concentrations in the center, to suppress metal diffusion and sintering, thereby enhancing insulation and electrostatic capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Sn is added to the dielectric layer to suppress metal diffusion and improve insulation characteristics, then the insulation characteristics and lifetime are improved, but the sintering and spheroidizing of internal electrode layers increases, reducing electrostatic capacity
Solution Approach 1:
The patent applies local quality by creating a non-uniform Sn concentration distribution within the dielectric layer. The Sn concentration is higher near the internal electrode layers (where metal diffusion suppression is most needed) and lower in the center region (where sintering effects are most harmful). This spatially varying composition allows the dielectric layer to provide insulation enhancement locally at the interfaces while minimizing the harmful spheroidizing effects in the bulk, thereby resolving the contradiction between improved insulation and maintained electrostatic capacity.
2Reliability
If Sn concentration is increased uniformly throughout the dielectric layer, then metal diffusion is suppressed and insulation is improved, but the spheroidizing effect reduces the continuity modulus of internal electrode layers
Solution Approach 1:
The patent implements local quality by establishing a gradient Sn concentration profile where the concentration varies by position within the dielectric layer. Specifically, the Sn concentration is highest at the interfaces with internal electrode layers (providing local protection against metal diffusion) and decreases toward the center. This localized high Sn concentration at critical interfaces suppresses metal diffusion and improves insulation characteristics, while the lower center concentration minimizes spheroidizing effects that would otherwise reduce the continuity modulus of internal electrode layers.
3Duration of action of stationary object
If high Sn concentration is used in the dielectric layer, then the lifetime is extended by suppressing metal diffusion, but the sintering effect causes disarrangement of multilayer structure
Solution Approach 1:
The patent applies local quality by creating a position-dependent Sn concentration distribution in the dielectric layer. The Sn concentration is elevated near the interfaces with internal electrode layers where metal diffusion suppression is most critical for extending lifetime. However, the Sn concentration is reduced in the central region of the dielectric layer where excessive Sn would cause sintering-induced disarrangement of the multilayer structure. This spatially differentiated composition enables the structure to achieve both extended lifetime through suppressed metal diffusion and maintained structural integrity.
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 improves the insulation characteristics and extends the lifetime of the ceramic electronic devices while maintaining high electrostatic capacity by controlling the Sn concentration gradient in the dielectric layers.
Implementation Method 1
metal diffusion from internal electrode layers into dielectric layers during firing
Implementation Method 2
Sn promotes sintering of the dielectric layer
Data Source
AI summary
A ceramic electronic device includes a multilayer structure in which each of a plurality of internal electrode layers and each of three or more of dielectric layers of which a main component is ceramic are alternately stacked. The three or more of dielectric layers include Sn. A dielectric layer having a smaller Sn concentration is closer to an outermost end in a stacking direction than a dielectric layer having a larger Sn concentration and being located on a center side of the stacking direction, in a relationship of at least two of the three or more of dielectric layers.