Multilayer Capacitor Sn-Doped Cover Grain Structure
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Solution Overview
Problem
Miniaturization of multilayer capacitors has led to reliability issues due to thinning dielectric layers, surface diffusion of grains, and reduced densification, affecting moisture resistance and chip characteristics like toughness and hardness.
Innovation Solution
A multilayer capacitor design with a core-shell structure in the cover regions, where the first cover region is doped with Sn, achieving 20% or more Sn-doped grains, and the second region has larger grains without Sn, optimizing grain size and molar ratios to enhance densification and chip characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the multilayer capacitor is miniaturized and the dielectric layer is thinned, then the capacitance density is improved, but the reliability deteriorates due to reduced densification and increased surface diffusion of grains
Solution Approach 1:
The patent applies local quality by creating two distinct cover regions with different grain structures: the first cover region (adjacent to the active region) contains Sn-doped core-shell structure grains with smaller size for high densification and moisture resistance, while the second cover region (outer portion) contains undoped grains for structural stability. This localized differentiation resolves the contradiction by providing high reliability at the critical interface without compromising overall device miniaturization.
Solution Approach 2:
The patent uses composite materials by combining Sn-doped core-shell structure grains with undoped grains in the cover portion. The core-shell structure itself is a composite with a doped core and undoped shell, creating a material system that achieves both high densification (through Sn doping) and controlled grain growth (through the undoped shell), thereby improving reliability while maintaining miniaturization benefits.
2Productivity
If high temperature shortening of sintering conditions is applied, then the productivity is improved, but the surface diffusion of grains is lowered and densification is reduced
Solution Approach 1:
The patent applies parameter changes by introducing Sn doping into the cover portion grains, which fundamentally alters the sintering behavior. The Sn dopant promotes densification at lower temperatures and suppresses excessive grain growth, allowing the use of shortened sintering cycles while maintaining high densification levels. This enables faster production without sacrificing manufacturing precision.
3Ease of manufacture
If the degree of densification of the cover portion is reduced, then the manufacturing complexity is lowered, but the moisture resistance characteristics deteriorate
Solution Approach 1:
The patent applies local quality by concentrating Sn-doped core-shell structure grains specifically in the first cover region adjacent to the active region, where moisture resistance is most critical. This localized approach provides enhanced moisture protection at the vulnerable interface without requiring complex manufacturing processes for the entire cover structure.
Solution Approach 2:
The patent uses composite materials by incorporating Sn-doped core-shell structure grains into the cover portion, creating a composite ceramic material that achieves high densification and moisture resistance. The core-shell structure provides a synergistic effect where the doped core promotes densification while the undoped shell controls grain growth, simplifying manufacturing while improving moisture resistance.
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 improves the density and reliability of the capacitor, maintaining moisture resistance and enhancing toughness and hardness, while preventing abnormal grain growth and ensuring proper sintering.
Implementation Method 1
the first cover region includes grains having a core-shell structure doped with Sn
Implementation Method 2
as high temperature shortening of sintering conditions is applied, the surface diffusion of grains is lowered, and thus, it is important to secure the densification of the sintered body
Data Source
AI summary
A multilayer capacitor includes a capacitor body including an active region having dielectric layers and internal electrodes alternately stacked therein, the capacitor body including upper and lower covers disposed on upper and lower surfaces of the active region, respectively; and an external electrode disposed on an external surface of the capacitor body. In one of the upper and lower covers, a portion thereof between a boundary surface of the active region and a boundary surface of the capacitor body is divided into a first cover region adjacent to the active region and a second cover region adjacent to the boundary surface of the capacitor body, and the first cover region includes grains having a core-shell structure doped with Sn. The first cover region includes 20% or more of Sn-doped core-shell structure grains, compared to the total of grains in the first cover region.