BaO-TiO2 Dielectric Ceramic Low-Temperature Co-Firing
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Solution Overview
Problem
Conventional dielectric ceramics with BaO—TiO2 compounds require high sintering temperatures, making it difficult to co-fire with low-melting-point conductor materials like Ag-based metals without melting, which leads to inadequate sintering and deterioration of dielectric properties and mechanical strength.
Innovation Solution
A dielectric ceramic composition with a BaTi4O9 and Ba2Ti9O20 crystal phase, combined with boron oxide and copper oxide as minor components, is used, allowing for low-temperature sintering while maintaining high Qf factors and relative permittivity, by adjusting the molar ratio of TiO2 to BaO and optimizing the X-ray diffraction peak intensity ratio and particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high sintering temperature (1000°C or higher) is used for BaO-TiO2 dielectric material, then sufficient sintering and good dielectric properties are achieved, but low-melting-point conductor materials like Ag-based metals melt during co-firing
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric material by introducing specific amounts of B2O3 (0.5-5.0 mass%) and CuO (0.1-3.0 mass%) as minor components. This composition modification lowers the sintering temperature from 1000°C or higher to below 900°C, enabling co-firing with Ag-based conductor materials while maintaining sufficient sintering density and dielectric properties through optimized crystal phase formation (BaTi4O9 and Ba2Ti9O20 phases with specific XRD intensity ratios).
2Temperature
If low sintering temperature is used to co-fire with Ag-based metals, then conductor material melting is avoided, but sufficient sintering cannot be achieved and dielectric properties deteriorate
Solution Approach 1:
The patent creates a composite dielectric system combining multiple crystal phases (BaTi4O9 and Ba2Ti9O20) with specific phase ratio control (XRD intensity ratio I29/I14 ≥ 1). The inclusion of B2O3 and CuO as sintering aids forms a eutectic system that enables low-temperature sintering below 900°C. This composite approach allows sufficient densification and phase formation at lower temperatures while maintaining good dielectric properties (Qf and εr) that would otherwise require high-temperature processing.
3Temperature
If larger amount of BaTi4O9 crystal phase is included for low-temperature firing, then sintering at lower temperature becomes possible, but dielectric properties such as relative permittivity and Qf deteriorate
Solution Approach 1:
The patent optimizes the crystal phase composition parameters by controlling the XRD peak intensity ratio I29/I14 to be 1 or more, ensuring adequate Ba2Ti9O20 phase content. Simultaneously, it introduces B2O3 and CuO as sintering aid components with specific concentration ranges (B2O3: 0.5-5.0 mass%, CuO: 0.1-3.0 mass%). This dual parameter optimization enables the material to achieve sufficient sintering at lower temperatures (below 900°C) while maintaining good dielectric properties, resolving the trade-off between phase composition and dielectric performance.
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 approach enables successful co-firing with Ag-based metals at lower temperatures, preserving dielectric properties and mechanical strength, and achieving low-loss dielectric materials suitable for high-frequency applications.
Implementation Method 1
a dielectric ceramic composition which includes a main component containing a BaTi4O9 crystal phase and a Ba2Ti9O20 crystal phase... and a minor component containing a boron oxide and a copper oxide
Implementation Method 2
a minor component that contains a boron oxide and a copper oxide, in which a content of the boron oxide in terms of B2O3 is in the range of 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the main component
Data Source
AI summary
A dielectric ceramic includes a main component and a minor component. The main component includes a BaTi4O9 crystal phase and a Ba2Ti9O20 crystal phase, is represented by BaO.xTiO2, has a molar ratio x of TiO2 to BaO of 4.6 to 8.0, and in X-ray diffraction, and has an X-ray diffraction peak intensity ratio I29/I14 of a maximum diffraction peak intensity (I14) of the BaTi4O9 crystal phase to a maximum diffraction peak intensity (W of the Ba2Ti9O20 crystal phase of 1 or more. The minor component includes a boron oxide and a copper oxide, in which the boron oxide content is in the range of 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the main component, and the copper oxide content is in the range of 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the main component.