MLCC Grain Orientation Control for Crack-Resistant Dielectrics
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Solution Overview
Problem
Existing multilayer ceramic capacitors lack sufficient mechanical strength and reliability, particularly in high permittivity applications.
Innovation Solution
The multilayer ceramic capacitors are designed with specific crystal grain orientations, where adjacent crystal grains have a difference in orientation within about 5 degrees, enhancing mechanical strength and reducing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional multilayer ceramic capacitor manufacturing is used, then production is simpler and faster, but mechanical strength and reliability are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystal grain orientation parameters during the sintering process. By adjusting the sintering temperature, holding time, and atmospheric conditions, the patent achieves a specific crystal grain orientation distribution where adjacent grains have orientation differences within about 5 degrees, thereby improving mechanical strength without requiring fundamental changes to the manufacturing process
Solution Approach 2:
The patent employs preliminary action by preparing the green body with specific particle size distribution and shape characteristics before sintering. The dielectric particles are pre-treated to have controlled size ranges (with 80% or more being 0.5-2.0 μm) and appropriate aspect ratios, which predisposes the material to form the desired crystal grain orientation structure during subsequent sintering, reducing the complexity of final microstructure control
2Reliability
If conventional manufacturing processes are used, then production efficiency is maintained, but crack formation and reliability are reduced
Solution Approach 1:
The patent replaces mechanical characterization methods with electron backscatter diffraction (EBSD) technology to evaluate crystal grain orientation. Instead of relying on mechanical strength tests as the primary evaluation method, the patent uses EBSD to directly measure and control the crystal grain orientation distribution, providing a more precise and non-destructive means to ensure reliability
Solution Approach 2:
The patent changes the evaluation parameter from macroscopic mechanical strength to microscopic crystal grain orientation angles. By measuring the orientation difference between adjacent crystal grains (keeping it within about 5 degrees), the patent establishes a more sensitive and reliable quality control parameter that directly correlates with crack resistance and overall device reliability
3Reliability
If high permittivity materials are used, then electrical performance is improved, but mechanical strength and reliability are compromised
Solution Approach 1:
The patent uses composite materials by combining barium titanate (high permittivity) with calcium zirconate and other modifiers to create a dielectric layer that maintains high permittivity while improving mechanical properties. The composite dielectric composition allows achieving both high electrical performance and enhanced mechanical strength through synergistic material interactions
Solution Approach 2:
The patent applies local quality by creating a core-shell structure in the dielectric particles, where the core contains high permittivity barium titanate and the shell contains calcium zirconate and other modifiers. This local differentiation allows the high permittivity material to provide electrical performance while the modified shell region provides mechanical strength and crack resistance, resolving the contradiction between electrical and mechanical properties
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including dielectric layers, inner electrode layers, first and second main surfaces facing each other in a height direction, first and second side surfaces facing each other in a width direction perpendicular or substantially perpendicular to the height direction, and first and second end surfaces facing each other in a length direction perpendicular or substantially perpendicular to the height direction and the width direction, and an outer electrode layer on the multilayer body and connected to some of the inner electrode layers. When crystal orientations of crystal grains in the dielectric layers are measured by electron backscatter diffraction, two or more pairs of adjacent crystal grains between which a difference in crystal orientation is within about 5 degrees with respect to a predetermined direction in a 2 μm-square observation area are present.