Ferrite Composition for Low-Temperature Sintering
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Solution Overview
Problem
Conventional ferrite materials for multilayer inductors face challenges with high Q values under high AC currents and downsizing, as they require higher sintering temperatures and suffer from decreased magnetic performance, especially when exposed to high magnetic fields and large amplitude currents.
Innovation Solution
A ferrite composition with specific ranges of iron oxide, copper oxide, zinc oxide, silicon oxide, bismuth oxide, and cobalt oxide, allowing for low-temperature sintering and maintaining high Q values even under high magnetic fields and high AC currents, enabling the downsizing of electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite materials are sintered at high temperatures (1050°C or higher) to achieve good magnetic properties, then the Q values are improved, but the sintering temperature exceeds the melting point of Ag coil conductors, making integral firing impossible
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperatures (1050°C or higher) to a lower range (900-1000°C) by modifying the ferrite composition. This is achieved by controlling the molar ratios of Fe2O3 (25-50%), CuO (5-15%), ZnO (0-40%), and NiO (balance), along with adding specific amounts of SiO2 (0.2-5.0 wt%), Bi2O3 (0.10-3.00 wt%), and Co3O4 (0.10-3.00 wt%). The composition modification enables achieving high Q values at lower sintering temperatures that are compatible with Ag coil conductor melting points.
Solution Approach 2:
The patent creates a composite ferrite material system by combining multiple metal oxides (Fe2O3, CuO, ZnO, NiO) with specific amounts of SiO2, Bi2O3, and Co3O4. This composite composition works synergistically to achieve both low-temperature sinterability and high magnetic performance. The SiO2 provides glass phase for low-temperature bonding, Bi2O3 enhances sintering activity, and Co3O4 improves magnetic properties, allowing the material to be sintered at temperatures below the melting point of Ag while maintaining high Q values.
2Volume of moving object
If ferrite materials are downsized to meet high densification requirements, then component size is reduced, but Q values tend to decrease
Solution Approach 1:
The patent changes the material composition parameters to enable high Q values in downsized components. By optimizing the Fe2O3 (25-50%), CuO (5-15%), ZnO (0-40%), and NiO content, along with adding SiO2 (0.2-5.0 wt%), Bi2O3 (0.10-3.00 wt%), and Co3O4 (0.10-3.00 wt%), the material achieves superior magnetic properties that maintain high Q values even when the inductor size is reduced. The low-temperature sintering capability also preserves grain structure integrity in smaller components.
3Power
If AC current amplitude is increased to meet higher power requirements, then power delivery is improved, but Q values deteriorate due to magnetic losses
Solution Approach 1:
The patent employs a composite ferrite composition with SiO2 (0.2-5.0 wt%), Bi2O3 (0.10-3.00 wt%), and Co3O4 (0.10-3.00 wt%) added to the base Fe2O3-CuO-ZnO-NiO system. This composite structure reduces magnetic losses under high AC currents through improved domain wall dynamics and reduced eddy current losses. The Bi2O3 and Co3O4 specifically enhance the material's ability to maintain high Q values under high amplitude currents by modifying the magnetic anisotropy and damping characteristics.
Solution Approach 2:
The patent optimizes the compositional parameters to change the magnetic loss characteristics. By controlling the CuO content (5-15%) and Co3O4 content (0.10-3.00 wt%), the material achieves reduced magnetic losses under high AC current conditions. The specific ratio of Fe2O3 (25-50%) to other oxides is adjusted to optimize the balance between saturation magnetization and magnetic loss, enabling high Q values even when high AC currents are applied.
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 ferrite composition achieves high Q values with minimal deterioration under high magnetic fields and AC currents, facilitating the downsizing of electronic components while maintaining low magnetic loss, making it suitable for applications like NFC coils and high-frequency inductors.
Implementation Method 1
the ferrite composition can be sintered at about 900° C., which is lower than the melting point of Ag available for inner electrodes
Data Source
AI summary
A ferrite composition comprises a main component and a sub component. The main component is comprised of 25.0 to 49.8 mol % iron oxide in terms of Fe2O3, 5.0 to 14.0 mol % copper oxide in terms of CuO, 0 to 40.0 mol % zinc oxide in terms of ZnO, and a remaining part of nickel oxide. The sub component includes 0.2 to 5.0 wt % silicon oxide in terms of SiO2, 0.10 to 3.00 wt % bismuth oxide in terms of Bi2O3, and 0.10 to 3.00 wt % cobalt oxide in terms of Co3O4, with respect to the main component.