Dielectric Ceramic Composition for X8R MLCC Reliability
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Solution Overview
Problem
Barium titanate-based dielectric materials used in multilayer ceramic capacitors face challenges in achieving X8R temperature characteristics and reliability, particularly at high temperatures, due to issues with capacitance stability and increased dissipation factor.
Innovation Solution
A dielectric ceramic composition is developed with a specific ratio of barium titanate-based crystal grains, including Ca-doped grains, and accessory ingredients such as oxides and carbonates of various elements, which are sintered to create a multilayer ceramic capacitor with improved temperature characteristics and reliability by controlling the average size ratio of crystal grains and adding CaZrO3 and rare earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If barium titanate-based dielectric material is used to achieve high permittivity and low dissipation factor, then room temperature electrical properties are improved, but X8R temperature characteristics and high temperature reliability deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ca content in different crystal grains (less than 2.5 mol% in first grains, 4.0-12.0 mol% in second grains) and adjusting the average size ratio between grain types (1.6-2.2). This compositional and structural parameter optimization enables the dielectric material to maintain low dissipation factor while achieving X8R temperature characteristics and high temperature reliability
Solution Approach 2:
The patent creates a composite microstructure consisting of two distinct crystal grain types with different Ca contents and sizes. The first crystal grains (low Ca content) and second crystal grains (high Ca content) form a composite structure that combines the advantages of both grain types, achieving both low dissipation factor and excellent temperature characteristics
2Quantity of substance
If barium titanate-based dielectric material is used to achieve high capacitance, then room temperature permittivity is improved, but capacitance temperature stability at high temperature deteriorates
Solution Approach 1:
The patent optimizes compositional parameters by controlling Ca content distribution and crystal grain size ratio to achieve X8R temperature characteristics, which specify capacitance stability within ±8% from -55°C to +150°C while maintaining high capacitance values
Solution Approach 2:
The dual-crystal-grain composite structure enables the material to maintain stable capacitance across wide temperature ranges. The first crystal grains contribute to high permittivity while the second crystal grains with higher Ca content provide thermal stability, achieving both high capacitance and X8R temperature characteristics
3Quantity of substance
If barium titanate-based dielectric material is used to achieve high permittivity, then room temperature electrical properties are improved, but high temperature withstand voltage and reliability deteriorate
Solution Approach 1:
The patent adjusts structural parameters including crystal grain size distribution and Ca content composition to improve high temperature withstand voltage characteristics while maintaining high permittivity. The controlled average size ratio of 1.6-2.2 between different grain types optimizes both electrical and thermal properties
4Ease of manufacture
If conventional dielectric material composition is used to simplify manufacturing, then manufacturing process is easier, but achieving X8R temperature characteristics becomes more difficult
Solution Approach 1:
The patent establishes specific parameter ranges for Ca content (less than 2.5 mol% and 4.0-12.0 mol% in different grains) and average size ratio (1.6-2.2) that guide the manufacturing process. These parameter specifications enable manufacturers to achieve X8R characteristics through controlled composition and sintering conditions
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 composition achieves X8R temperature characteristics and excellent high-temperature withstand voltage, reducing the pore fraction at triple points and maintaining low dissipation factors, thus enhancing the reliability and capacitance stability of the multilayer ceramic capacitors.
Implementation Method 1
a fine structure after sintering, crystal grains in which a content of Ca is less than 2.5 mol % are first crystal grains, crystal grains in which the content of Ca is 4.0 to 12.0 mol % are second crystal grains
Data Source
AI summary
A dielectric material includes a barium titanate based base material main ingredient and an accessory ingredient. In a fine sintered structure of the dielectric material, crystal grains in which a content of Ca is less than 2.5 mol % are first crystal grains, crystal grains in which the content of Ca is 4.0 to 12.0 mol % are second crystal grains, and a ratio of an average size of the first crystal grains to an average size of the second crystal grains is in a range of 1.6 to 2.2.