Multilayer Ceramic Capacitor Cu Electrode Sintering
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Solution Overview
Problem
Existing multilayer ceramic capacitors with CaZrO3 dielectric porcelain and Cu internal electrodes face challenges in achieving optimal sintering properties and longevity, particularly when sintered at low temperatures, as they require longer times and complex processes to achieve desired characteristics.
Innovation Solution
A multilayer ceramic capacitor composition with a dielectric layer comprising CaZrO3, Mn, Li, B, and Si, expressed as 100CaxZrO3+aMnO2+bLiO1/2+cBO3/2+dSiO2+eAlO3/2, where specific constituent ratios are optimized to improve sintering density and longevity, allowing for sintering at 1000°C or below in a reducing atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-temperature sintering (1080°C or below) is used with Cu internal electrodes, then cost is reduced and Q value is improved, but oxidation of Cu occurs and reliability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric porcelain by specifying precise ratios of CaO (30-40 mol%), ZrO2 (50-60 mol%), and MnO2 (0.1-5 mol%), creating a non-reducing atmosphere composition that prevents Cu oxidation at low sintering temperatures
Solution Approach 2:
MnO2 acts as an intermediary substance that creates a protective atmosphere during sintering, preventing oxidation of Cu internal electrodes while enabling low-temperature processing. The MnO2 decomposes to release oxygen that protects the Cu from oxidizing
2Reliability
If Pb and Bi are added to improve sintering properties and longevity, then dielectric performance is enhanced, but environmental impact increases
Solution Approach 1:
The patent replaces expensive and environmentally harmful Pb/Bi additives with a MnO2-based composition system that achieves similar or superior performance without toxic elements, making the material both cheaper and environmentally friendly
Solution Approach 2:
The patent creates a composite dielectric system combining CaO-ZrO2-MnO2 in specific ratios, where the synergistic interaction between components achieves high dielectric performance and longevity without requiring Pb or Bi additives
3Reliability
If complex heat treatment processes are used to improve longevity, then reliability is enhanced, but manufacturing complexity and time increase
Solution Approach 1:
The patent merges the sintering process with the atmosphere control function by incorporating MnO2 into the dielectric composition itself, eliminating the need for separate reducing atmosphere heat treatment steps while achieving the same longevity enhancement
Solution Approach 2:
The MnO2 is pre-incorporated into the dielectric green sheet composition before sintering, so that during the normal sintering process it automatically creates the protective atmosphere needed for Cu oxidation prevention, eliminating subsequent complex heat treatment steps
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 optimized composition enables faster sintering while maintaining high longevity traits and dielectric performance, ensuring a denser ceramic structure and improved reliability of the multilayer ceramic capacitors.
Implementation Method 1
the dielectric must be a non-reducing material that can be sintered at low temperatures of 1080° C. or below
Implementation Method 2
prevents oxidation of Cu
Data Source
AI summary
A multilayer ceramic capacitor uses internal electrodes which are embedded between the dielectric layers and whose primary constituent is Cu, wherein when the composition of the dielectric layer is expressed by 100CaxZrO3+aMnO2+bLiO1/2+cBO3/2+dSiO2+eAlO3/2, the contents of the respective constituents are 1.5≦a≦4.5 mol, 0.8≦b/(c+d)≦2.0, 0.9≦d/c≦1.5, and 0≦e≦0.3 mol relative to 100 mol of CaxZrO3 (where 1.005≦x≦1.06), and when 10≦(b+c+d)≦14.9, an upper limit of x is defined by a line passing through (10, 1.03) and (14.9, 1.06), and a lower limit of x is defined by a line passing through (10, 1.005) and (14.9, 1.02), wherein the coordinates indicate ((b+c+d), x).