Multilayer Ceramic Capacitor Grain Structure to Suppress Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ceramic electronic devices with BaTiO3-based dielectric layers face issues with high reactivity and grain growth, leading to electric distortion and potential cracking when voltage is applied, due to the replacement of Ba by Ca and Ti by Zr, which affects the reliability and durability of the materials.
Innovation Solution
A multilayer ceramic capacitor design featuring dielectric layers and internal electrode layers alternately stacked with specific grain diameter ratios and side margin sections, using ceramic grains of (Ba1-x-yCaxSry)(Ti1-zZrz)O3, where the average grain diameters in different sections are carefully controlled to ensure D3 < D1 < D2, and the thickness and width of internal electrode layers are optimized to suppress cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ba is replaced by Ca and Ti is replaced by Zr in BaTiO3 to improve reliability, then the material has higher reliability than BaTiO3, but the reactivity and grain growing characteristic become high causing electric distortion and potential cracking
Solution Approach 1:
The patent applies local quality by creating distinct regions with different grain diameters within the dielectric layer. Specifically, it defines a first region with a first average grain diameter, a second region with a second average grain diameter, and a third region with a third average grain diameter, where each region has controlled grain size characteristics. This local differentiation allows the material to maintain high reliability through controlled grain growth while preventing electric distortion and cracking by managing reactivity in specific areas rather than uniformly throughout the entire dielectric layer.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the grain diameter parameters (first average grain diameter, second average grain diameter, and third average grain diameter) and their relationships. By establishing specific parameter ranges and relationships between these grain diameter parameters, the invention transforms the material properties to achieve both high reliability and adequate strength, resolving the contradiction between improved reliability and potential strength reduction due to high reactivity and grain growth.
2Manufacturing precision
If dielectric paste is applied next to internal electrode layer to eliminate level difference, then level difference is eliminated, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming green sheets with predetermined patterns before stacking. The green sheets are prepared in advance with specific ceramic particle arrangements and electrode patterns, allowing the level difference elimination to be achieved through the pre-designed structure rather than requiring additional corrective steps during assembly. This preliminary preparation reduces the overall process complexity while maintaining manufacturing precision.
3Reliability
If glass-coating process and composition change are performed to improve humidity resistance, then humidity resistance is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges multiple functions into the dielectric layer itself by incorporating humidity resistance properties directly into the ceramic material composition and structure. Instead of adding separate glass-coating layers or performing additional composition changes as separate processes, the invention integrates humidity resistance functionality into the fundamental dielectric layer structure through controlled grain growth and regional differentiation, thereby improving humidity resistance while avoiding increased manufacturing process complexity.
Data Source
AI summary
A ceramic electronic device includes a multilayer structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked. Each of the plurality of dielectric layers includes ceramic grains of a main component thereof expressed by (Ba1-x-yCaxSry)(Ti1-zZrz)O3 (0<x≤0.2, 0≤y≤0.1, 0≤z≤0.1). D3<D1<D2 is satisfied when an average grain diameter of the ceramic grains of the main component of the plurality of dielectric layers in a section in which each two internal electrode layers is D1, an average grain diameter of the ceramic grains of the main component of first dielectric layers which are located at different height positions from the internal electrode layers is D2, an average grain diameter of the ceramic grains of the main component of second dielectric layers which are located at same height positions of the internal electrode layers is D3.