Low-Temperature Co-Fired Microwave Dielectric Ceramic
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Solution Overview
Problem
Current microwave dielectric materials face challenges in achieving low-temperature co-firing while maintaining effective processing and electrical properties, particularly due to high sintering temperatures that restrict their industrial application with metals like Cu and Ag, and the addition of low-melting-point oxides can compromise material properties.
Innovation Solution
A ceramic composite is developed using a eutectic composition of Mg2SiO4 and Ca2SiO4 with additives CaTiO3 and CaZrO3, combined with a glass material formulation of Li2O, BaO, SrO, CaO, B2O3, and SiO2, allowing for low-temperature sintering (900-970°C) and co-firing with Ag or Cu, while maintaining a low dielectric constant, high quality factor, and insulation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microwave dielectric materials (Mg2SiO4, Ca2SiO4) are used to achieve low dielectric constant and high quality factor, then the electrical properties are improved, but the sintering temperature becomes too high (>1200°C) for low-temperature co-firing with Cu and Ag electrodes
Solution Approach 1:
The patent combines Mg2SiO4 and Ca2SiO4 in a specific molar ratio (0.3-0.7) to create a composite ceramic material. This composite structure allows the material to benefit from the low dielectric constant and high quality factor of both components while achieving a eutectic composition that lowers the sintering temperature to 900-1100°C, making it suitable for co-firing with low-melting-point electrodes.
2Temperature
If low-melting-point oxide or glass material (B2O3, V2O5) is added to decrease sintering temperature, then the sintering temperature is reduced, but the material properties (high frequency dielectric property) are compromised or processing becomes difficult
Solution Approach 1:
The patent changes the compositional parameters by using a specific molar ratio of Mg2SiO4 to Ca2SiO4 (0.3-0.7) to achieve a eutectic composition. This parameter optimization allows the material to undergo liquid phase sintering at lower temperatures (900-1100°C) without requiring additional low-melting-point additives, thereby maintaining excellent high frequency dielectric properties and processing stability.
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 solution enables the production of microwave dielectric ceramic materials with a dielectric constant of 8-15, quality factor of 2900-6500, and insulation resistance of ≥3.5×10^12Ω, suitable for applications in capacitors and filters, with reduced sintering temperature and improved processing stability.
Implementation Method 1
adding the oxide or glass material with low melting point such as B2O3 or V2O5 etc. to produce a molten liquid phase at low temperature
Implementation Method 2
sintering into dense structure at a temperature of 900-970° C. and co-firing with Ag in ambient environment and with Cu in inert atmosphere
Data Source
AI summary
A low-temperature co-fired microwave dielectric ceramic material includes: (a) 85 wt % to 99 wt % ceramic material comprising Mg2SiO4, Ca2SiO4, CaTiO3, and CaZrO3, wherein a weight ratio of Mg2SiO4 relative to Ca2SiO4 is of (1−x):x, a weight ratio of CaTiO3 relative to CaZrO3 is of y:z, and a weight ratio of entities of Mg2SiO4 and Ca2SiO4 relative to CaTiO3 is of (1−y−z):y, 0.2≤x≤0.7, 0.05≤y≤0.2, 0.05≤z≤0.4; and (b) 1 wt % to 15 wt % glass material composed of Li2O, BaO, SrO, CaO, B2O3, and SiO2.