MLCC Margin Region Composition for Sintering Contraction Control
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Solution Overview
Problem
The reliability of multilayer ceramic capacitors is compromised due to reduced dielectric layer thickness, leading to increased voltage stress, structural defects, and degraded humidity resistance, as existing methods fail to adequately address the level differences and contraction issues during sintering.
Innovation Solution
A multilayer ceramic capacitor design with alternating dielectric and internal electrode layers, where the margin regions have higher concentrations of Mn, Si, and B, and lower donor element concentrations compared to the dielectric layers, to minimize level differences and sintering contraction disparities, thereby enhancing structural integrity and humidity resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the dielectric layer is reduced to downsize the multilayer ceramic capacitor, then the chip size is reduced, but the voltage applied to each dielectric layer increases and reliability is degraded
Solution Approach 1:
The patent applies local quality by creating a margin region with different composition than the main dielectric layer. The margin region has higher concentrations of Mn, Si, and B, which modify the local properties to reduce level differences and improve reliability at critical interfaces, while the main dielectric layer maintains its thin thickness for miniaturization.
2Volume of moving object
If the thickness of the dielectric layer is reduced to downsize the multilayer ceramic capacitor, then the chip size is reduced, but the lifetime of the dielectric layer is shortened
Solution Approach 1:
The margin region with specific composition (higher Mn, Si, B) is created to protect the dielectric layer at critical interfaces. This local modification extends the lifetime by preventing degradation at the margins where stress and moisture intrusion are most severe, allowing the thin dielectric layers to maintain their functionality longer.
3Quantity of substance
If the number of dielectric layers is increased to maintain capacitance with reduced thickness, then the capacitance is maintained, but level differences increase and structural defects such as delamination occur
Solution Approach 1:
The margin region acts as a buffer zone that compensates for the cumulative level differences created by multiple thin dielectric layers. The different composition (higher Mn, Si, B) provides a transition zone that reduces the abruptness of the level difference, thereby preventing delamination and maintaining structural stability.
Solution Approach 2:
The margin region is created beforehand to cushion against the level differences that will occur during sintering. By pre-establishing this buffer zone with appropriate composition, the patent prevents the formation of micro clearances and subsequent delamination before they can occur during the sintering process.
4Shape
If a reverse pattern of ceramic paste is printed to absorb level differences, then the level difference is absorbed, but micro clearances occur due to contraction difference and humidity resistance is degraded
Solution Approach 1:
Instead of using a reverse pattern that creates micro clearances, the patent creates a margin region with fundamentally different composition (higher Mn, Si, B and lower donor elements). This compositional difference creates a gradual transition zone that eliminates micro clearances while maintaining humidity resistance, as the margin region's composition is specifically optimized to prevent moisture intrusion.
5Manufacturing precision
If glass film is used to cover ceramic powder to reduce contraction difference, then the contraction difference is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the compositional parameters of the ceramic paste itself by adjusting the concentrations of Mn, Si, B, and donor elements in the margin region. This compositional modification directly controls the sintering behavior and contraction characteristics, eliminating the need for additional glass film layers or complex manufacturing processes.
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 improves the reliability and lifespan of multilayer ceramic capacitors by reducing structural defects and humidity intrusion, while maintaining high dielectric constant and bias characteristics.
Implementation Method 1
a micro clearance may occur between an end of the internal electrode layers and the side margin region because of a difference of contraction in sintering between the capacity region and the side margin region
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer structure in which each of a plurality of dielectric layers and each of a plurality of internal electrode layers are alternately stacked, wherein concentrations of Mn, Si and B of a margin region are respectively higher than concentrations of Mn, Si and B of the dielectric layers, wherein a donor element concentration of the margin region is lower than a donor element concentration of the dielectric layers, wherein the margin region is at least one of an end margin region and a side margin region.