Multi-Layer Ceramic Capacitor Low-Temperature Sintering
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Solution Overview
Problem
Existing multi-layer ceramic capacitors face challenges in achieving smaller size, higher capacitance, and reliable high-temperature performance while maintaining flat temperature characteristics and sufficient permittivity, often requiring high baking temperatures and specific additives that complicate the manufacturing process.
Innovation Solution
A multi-layer ceramic capacitor design using Cu or Cu alloy internal electrodes, BaTiO3-based perovskite dielectric ceramics with a domain pattern and shell structure, sintered at 1,080°C or lower in a reducing atmosphere, which allows for a permittivity of 2,000 or more and satisfies X7R or X8R temperature characteristics, with controlled grain size and shell thickness to enhance insulation and life time properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a non-reducing dielectric substance porcelain composition is used to achieve smaller size and large capacitance, then the capacitance and size are improved, but the baking temperature must be 1,100°C or higher which increases energy consumption
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric substance by incorporating specific metal oxides (Bi2O3 at 0.1-5 wt%, ZnO at 0.1-5 wt%, B2O3 at 0.1-5 wt%) to modify the sintering characteristics. This composition adjustment enables the material to achieve adequate permittivity and temperature characteristics at lower baking temperatures (900-1,050°C) while maintaining the desired capacitance values.
Solution Approach 2:
The patent creates a composite dielectric material system combining BaTiO3 base material with multiple additive oxides (Bi2O3, ZnO, B2O3, SiO2, Al2O3). This composite approach allows the material to exhibit both low-temperature sinterability and high permittivity, resolving the contradiction between energy efficiency and capacitance performance.
2Reliability
If additives are added to provide anti-reducing property, then the reliability is improved, but the baking temperature must be 1,100°C or higher which increases manufacturing complexity
Solution Approach 1:
The patent modifies the chemical composition by incorporating Bi2O3, ZnO, and B2O3 which form protective phases during sintering that provide anti-reducing properties. This composition change enables the material to maintain reliability at lower baking temperatures without requiring complex high-temperature processing or additional protective additives.
Solution Approach 2:
The added metal oxides (Bi2O3, ZnO, B2O3) act as intermediary substances that form protective layers or phases during sintering, preventing reduction reactions without requiring extremely high temperatures. These intermediaries enable reliable sintering at 900-1,050°C by mediating between the Cu internal electrodes and the dielectric material.
3Quantity of substance
If a core-shell structure with additive diffusion is used to achieve high permittivity, then the permittivity is improved, but the baking temperature must be 1,100°C or higher which reduces energy efficiency
Solution Approach 1:
The patent achieves high permittivity (ε≧2,000) by optimizing the base material composition (BaTiO3 with specific ratios of Ca, Sr, Zr, Hf substitutions) and controlling grain size (400 nm or less diameter). This parameter optimization enables high permittivity at lower baking temperatures without requiring extensive additive diffusion that would necessitate 1,100°C or higher processing.
Solution Approach 2:
Instead of relying on additive diffusion within crystal grains (a three-dimensional process requiring high temperature), the patent achieves high permittivity through nanoscale grain size control and surface shell formation. This dimensional approach (focusing on grain boundary effects and surface properties) enables high permittivity at lower temperatures by exploiting surface phenomena rather than bulk diffusion.
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 design achieves a multi-layer ceramic capacitor with improved size, capacitance, and high-temperature performance, maintaining flat temperature characteristics and extended life time under 150°C-20 V/μm conditions, while being sintered at a lower temperature, thus optimizing energy efficiency and reliability.
Implementation Method 1
the dielectric ceramics are sintered body of a perovskite type dielectric substance mainly comprising BaTiO3 (BT) constituted with grains having an average value for the diameter of 400 nm or less as viewed on a cross section and grain boundaries, and the grain comprises a dielectric substance having a domain pattern and a shell formed on the surface of the dielectric substance
Implementation Method 2
the dielectric ceramics are sintered body of a perovskite type dielectric substance mainly comprising BaTiO3 (BT) constituted with grains having an average value for the diameter of 400 nm or less as viewed on a cross section and grain boundaries
Data Source
AI summary
A multi-layer ceramic capacitor capable of being sintered at 1,080° C. or lower in a reducing atmosphere, having a permittivity of 2,000 or more, a temperature characteristic of X7R characteristic or X8R characteristic, and favorable life time property, in which the internal electrodes are formed of Cu or a Cu alloy, the dielectric ceramics are constituted with grains each of an average value for the diameter of 400 nm or less as viewed on the cross section and grain boundaries, the grain comprises a dielectric substance having a domain pattern and shells formed on the surface of the dielectric substance and with t/D from 2% to 10% where D represents an average value for the diameter of the grains as viewed on the cross section and t represents the average value for the thickness of the shells.