Multilayer Ceramic Capacitor Protective Region Grain Size
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in suppressing hydrogen diffusion in the form of protons, leading to degradation of insulating properties, especially during plating processes and high temperature, high humidity conditions.
Innovation Solution
A multilayer ceramic capacitor design featuring a protective region with a larger average grain diameter and higher donor element concentration in the cover layer compared to the capacity region, which reduces grain boundary diffusion and oxygen defects, thereby inhibiting proton diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multilayer structure is used, then manufacturing is simple, but hydrogen diffusion causes degradation of insulating property
Solution Approach 1:
The patent applies local quality by creating a protective region with distinct properties (larger grain diameter, higher donor element concentration) at the circumference of the multilayer structure, while maintaining different properties in the central capacity region. This localized modification provides targeted protection against hydrogen diffusion without altering the entire structure, thus improving reliability while minimizing complexity increase.
Solution Approach 2:
The multilayer structure is segmented into functionally distinct regions: a central capacity region for electrical function and a surrounding protective region for barrier function. This segmentation allows each region to be optimized independently - the capacity region maintains fine grain structure for high capacitance while the protective region has coarse grain structure for hydrogen barrier properties.
2Reliability
If grain diameter is increased to suppress proton diffusion, then hydrogen barrier property improves, but capacitance performance may deteriorate
Solution Approach 1:
Different grain diameters are applied locally to different regions: the protective region has larger grain diameter (5 μm to 20 μm) for hydrogen barrier properties, while the capacity region maintains smaller grain diameter for high capacitance. This resolves the contradiction by ensuring each region's grain structure serves its specific function without compromising the other.
Solution Approach 2:
The structure is divided into protective region and capacity region with distinctly different grain structures. The protective region's coarse grains provide long diffusion paths for protons, while the capacity region's fine grains provide high dielectric constant and capacitance, eliminating the need to compromise either property in a uniform structure.
3Reliability
If donor element concentration is increased to reduce oxygen defects, then proton diffusion resistance improves, but manufacturing precision requirements increase
Solution Approach 1:
The protective region is formulated with higher donor element concentration (0.01 at% to 0.1 at%) compared to the capacity region, creating a localized zone with enhanced proton diffusion resistance. This local enrichment can be achieved through targeted additive formulation and sintering conditions without requiring ultra-precise control across the entire structure.
Solution Approach 2:
The protective region is designed with predetermined donor element concentration and grain structure characteristics before the sintering process. By pre-formulating the protective region's composition and sintering parameters, the patent reduces the complexity of real-time manufacturing control while ensuring consistent proton barrier properties.
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
Effectively suppresses hydrogen diffusion as a proton, enhancing the insulating properties and durability of the capacitor under challenging conditions.
Implementation Method 1
at least a part of the circumference region has a protective region of which an average grain diameter of a main component ceramic is larger than that of the capacity region and of which a concentration of a donor element in the main component ceramic is larger than that of the capacity region
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer structure in which each of ceramic dielectric layers and each of internal electrode layers are alternately stacked, the plurality of internal electrode layers being alternately exposed to a first edge face and a second edge face of the multilayer structure, wherein: a region in which a set of internal electrode layers exposed to the first edge face of the multilayer structure face with another set of internal electrode layers exposed to the second edge face of the multilayer structure is a capacity region; at least a part of the circumference region around the capacity region has a protective region of which an average grain diameter of a main component ceramic is larger than that of the capacity region and of which a concentration of a donor element in the main component ceramic is larger than that of the capacity region.