Multilayer Ceramic Structure With Graded Dielectric Particles Against Cracking
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Solution Overview
Problem
Existing multilayer ceramic electronic devices face challenges in restraining cracking and improving reliability with favorable temperature characteristics.
Innovation Solution
A multilayer electronic device with an element body comprising an interior region of alternately laminated inner dielectric and internal electrode layers, and an exterior region with outer dielectric layers, utilizing main-phase particles with a perovskite crystal structure and specific compositions and particle size ratios, along with controlled RE, M, and Si contents, to enhance mechanical strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relative permittivity is improved by changing particle sizes between first dielectric particles in interior region and second dielectric particles in exterior regions, then the electrical performance is enhanced, but the mechanical strength and reliability deteriorate due to increased cracking risk
Solution Approach 1:
The patent applies local quality by differentiating the composition and particle size characteristics between interior and exterior regions. Specifically, the exterior region contains dielectric particles with larger average particle size and different composition ratios compared to the interior region, allowing each region to be optimized for its specific function (electrical performance in interior, mechanical strength in exterior) while working together as a unified structure.
2Strength
If the exterior region hardness is increased to prevent cracking from external impact and electrostriction, then the mechanical strength is improved, but the manufacturing precision and composition control become more difficult
Solution Approach 1:
The patent employs parameter changes by precisely controlling multiple compositional parameters in the exterior region, including the ratio of average particle size of second dielectric particles to sintered body length (0.003 to 0.015), RE content (0.5 to 5.0 wt%), and M element content (0.1 to 3.0 wt%). These parameter optimizations enable the exterior region to achieve high hardness and cracking resistance while maintaining manufacturability through defined compositional ranges.
3Reliability
If the particle size distribution is optimized to enhance electrical characteristics, then the relative permittivity is improved, but the uniformity and homogeneity of the structure are compromised
Solution Approach 1:
The patent applies segmentation by dividing the dielectric structure into distinct interior and exterior regions with different particle size characteristics and compositions. The interior region focuses on electrical performance with smaller, more uniform particles, while the exterior region uses larger particles for mechanical strength. This segmentation allows each region to be optimized independently for its primary function while maintaining overall structural integrity.
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 device effectively prevents cracking and improves reliability by maintaining high mechanical strength and favorable temperature characteristics, as evidenced by extended high temperature load life.
Implementation Method 1
main-phase particles in the inner dielectric layers and outer dielectric layers of the exterior region include a main component having a perovskite crystal structure represented by a general formula of ABO3
Data Source
AI summary
A multilayer electronic device includes an element body and a pair of external electrodes. The element body includes an interior region in which inner dielectric layers and internal electrode layers are alternately laminated and an exterior region located outside the interior region in its lamination direction. The pair of external electrodes exists on surfaces of the element body. Main-phase particles in the inner dielectric layers and outer dielectric layers of the exterior region include a main component having a perovskite crystal structure represented by a general formula of ABO3. r1<r2<r1×4.0 is satisfied, in which r1 is an average particle size of the main-phase particles constituting the inner dielectric layers, and r2 is an average particle size of the main-phase particles constituting the outer dielectric layers.