MLCC Grain Size Matching for Breakdown Voltage Reliability
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Solution Overview
Problem
Multilayer ceramic capacitors face reduced withstand voltage reliability due to thinning of inner dielectric layers, leading to decreased contact area and breakdown voltage.
Innovation Solution
The use of multilayer ceramic capacitors with inner and outer dielectric layers having grains with an average grain size difference of 100 nm or less, ensuring improved contact and reduced compressive stress at interfaces, thereby enhancing breakdown voltage reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inner dielectric layers are thinned to reduce size and increase capacitance, then the capacitance increases and size decreases, but the contact area between inner dielectric layers and dielectric layers decreases, making peeling easier and reducing breakdown voltage and withstand voltage reliability
Solution Approach 1:
The patent applies local quality by creating a gradient in grain size across different regions of the dielectric layer. The inner dielectric layer has a first average grain size while the outer dielectric layer has a second average grain size that is 5 nm to 50 nm larger. This localized variation in grain size optimizes each region's properties: the inner layer maintains high capacitance density, while the outer layer provides enhanced mechanical strength and peeling resistance, thereby resolving the contradiction between capacitance and withstand voltage reliability.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the grain size parameter of the dielectric material. By adjusting the average grain size of the inner and outer dielectric layers to differ by only 5 nm to 50 nm, the invention optimizes the balance between capacitance and reliability. This controlled parameter variation ensures that the inner layer remains thin for high capacitance while the outer layer provides sufficient mechanical support, preventing peeling and maintaining high breakdown voltage.
2Quantity of substance
If the inner dielectric layers are thinned, then the capacitance increases, but the breakdown voltage decreases
Solution Approach 1:
The patent applies local quality by creating a gradient in grain size across different regions of the dielectric layer. The inner dielectric layer has a first average grain size while the outer dielectric layer has a second average grain size that is 5 nm to 50 nm larger. This localized variation in grain size optimizes each region's properties: the inner layer maintains high capacitance density, while the outer layer provides enhanced mechanical strength and peeling resistance, thereby resolving the contradiction between capacitance and withstand voltage reliability.
Solution Approach 2:
The patent employs composite materials by combining dielectric layers with different grain size characteristics. The inner dielectric layer with smaller grain size provides high capacitance, while the outer dielectric layer with slightly larger grain size provides enhanced breakdown voltage and mechanical strength. This composite structure allows the capacitor to achieve both high capacitance and high breakdown voltage simultaneously.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including an inner layer portion including internal electrode layers and inner dielectric layers laminated alternately, and internal electrode layers at both ends thereof in a lamination direction, and outer dielectric layers covering the inner layer portion, and two external electrodes on both end surfaces of the multilayer body in a length direction intersecting the lamination direction. The inner and outer dielectric layers each include grains, and a difference between an average grain size of grains in the inner dielectric layers and an average grain size of grains in the outer dielectric layers is about 100 nm or less.