Market development of soft ferrite materials
In recent years, the development of electronic products in light, thin, short and small directions has put forward higher requirements for the performance of soft ferrite materials. Among them, high magnetic permeability manganese-zinc materials are the fastest changing market with the market. One of the best materials in the future. High magnetic permeability MnZn ferrite materials are mainly used in electronic circuit broadband transformers, integrated services digital network (ISDN), local area network (LAN), wide area network (WAN), background lighting and other fields of pulse transformers, anti-electromagnetic wave filters And other fields. The magnetic cores in these fields are basically working in a weak field, and the high magnetic permeability of the material will show unique advantages.
1. First, when the magnetic permeability of the material is high, the number of coil turns can obtain the required inductance, thereby effectively reducing the DC resistance of the coil and the loss caused by the coil.
Secondly, the use of materials with high magnetic permeability can significantly reduce the volume of the transformer, which is conducive to miniaturization and weight reduction of devices and systems. These characteristics are in line with the development trend of electronic products, which currently account for more than 25% of the total output of all soft ferrites.
With the rapid development of electronic information industry such as communication, computer and network, its market demand is growing at an average annual rate of more than 20%. Therefore, domestic and foreign related companies attach great importance to the study of high magnetic permeability MnZn ferrite, and research results are constantly emerging. Advances in Materials Research The development of early high-conductivity materials was only one-sided pursuit of high magnetic permeability and a certain Curie temperature. However, the application of this material in practice is very limited. A large number of applications in the application market require that the material not only have high initial permeability, but also good temperature, frequency characteristics, low loss, high impedance and good Superposition performance, etc. This requires a good balance between material properties while improving magnetic permeability while taking into account other performance parameters.
Research in the field of high magnetic permeability has shifted from the simple pursuit of high magnetic permeability to the improvement of comprehensive performance, which is the current development trend of high permeability ferrite, and its market demand has the following salient features:
1 Universal Wide Temperature Requirements Currently, market demand imposes wide temperature requirements on the performance of many materials. The magnetic permeability has a wide temperature characteristic. Outdoor facilities of modern communication equipment, such as repeaters, sound amplifiers, microwave relay stations, submarine cables, and underwater equipment for optical cables, not only require high temperature resistance, but also withstand severe cold, requiring communication equipment to work reliably and stably. Therefore, many customers require materials ranging from -40 to +80 ° C, even to a wide temperature range of 125 ° C, the inductance can meet the requirements, which requires high permeability of materials from low to high temperatures.
2 has a high Curie point. This material is mainly used in automotive electronics. Due to the special conditions in the car, the working temperature is required to be -50 to +150 °C. Generally, the Curie temperature of high magnetic permeability materials is difficult to reach such a high level.
3 impedance has a wide temperature characteristic. One of the most important component indicators for common mode chokes for electromagnetic interference is impedance, and some customers require materials to meet the requirements over a wide temperature range.
4 Low harmonic distortion (THD) has a wide temperature characteristic. With the rapid development of network technology, xDSL modems have been widely used. The core of this type of material is required to have a low THD. Many downstream companies now require magnetic core THD not only at room temperature, but also require materials to meet requirements at -20 ° C or even wider temperature range. .
5 high DC superposition has wide temperature characteristics.
2. Low harmonic distortion (THD) requirements. In recent years, communication technology has developed rapidly, and xDSL (including asymmetric digital subscriber line ADSL and symmetric digital subscriber line SDSL) technology has been widely cited. The demand for high permeability ferrite cores for isolation, impedance matching, and high-low-pass filtering is increasing, and higher requirements are placed on ferrite cores. In order to reduce waveform distortion during signal transmission, reduce transmission errors, and extend the transmission distance, the transformer is required to have low total harmonic distortion.
Total harmonic distortion is directly related to the performance of the core material, the geometry of the core, and the design of the transformer. Among them, the index related to the performance of the magnetic core material is the specific hysteresis loss coefficient ηB, which characterizes the loss characteristics of the ferrite material under a certain magnetic flux density change. Manufacturers at home and abroad have attached great importance to this market and actively responded to the development of their respective low THD materials.
3. DC superposition requirements With the large-scale development of local area networks (LANs), the transmission speed of 100 Mbps has become the mainstream. In order to achieve miniaturization and thinning of devices, and to meet the requirements of inductance under DC bias conditions, a large number of irons with good superposition performance are required. Oxygen core. In this regard, TDK first developed DN45 material, μi=4500±25%, and its use temperature is between 0-70 °C. Compared with the traditional HP5 material (5000±25%), its DC superposition characteristic is improved by 30. %the above. Subsequently, with the proposal of wide temperature requirements, the company has developed a new DNW45 material that can work at -40 ~ 85 ° C, its μi = 4200 ± 25%, compared with DN45, its DC superposition characteristics increased by 23% .
4. High impedance requires the rapid development of electronic technology, making electromagnetic pollution problems increasingly prominent. In order to limit the harm of electromagnetic interference, many countries have established electromagnetic compatibility standards for electronic products, requiring electronic equipment to resist electromagnetic interference to a certain standard, and the electromagnetic interference to the periphery must be limited to a certain extent. This requires a large number of EMI cores, the most important component of which is impedance. The absorbing material also plays an important role in electromagnetic interference, making the electromagnetic compatibility test easier to pass, and convenient and quick, and attaching the absorbing material.
In addition, more and more customers are also demanding high stability of materials, including:
1) Stress stability requires that the material has a small drop in inductance after stress is generated due to winding, packaging, compression springs, etc.;
2) The stability of time requires that the material drop factor be small;
3) Temperature stability, temperature coefficient and thermal shock resistance are required to meet the requirements;
4) Magnetic field stability, including the quality factor Q value and the stability of the hysteresis loss coefficient ηB in a weak magnetic field.
(This article is transferred from Big Bit)