Winding inductor development and product lineup

In recent years, with the development of automotive electronics, various digital devices for automotive use, including audio and car navigation systems, have gradually increased. In addition, the phenomenon of using on-vehicle cameras as standard equipment has also emerged in various countries, and it is expected that relevant markets will expand in the near future. Since these digital devices have various circuits that require inductors such as power inductors, yoke coils, and antenna matching devices, the demand for inductors will increase as the automotive market expands.

Although the inductor specifications required for each application are different, one common requirement for inductors used in automotive digital devices is "high reliability." Compared to inductors used in general life equipment such as mobile phones, inductors used in on-vehicle digital devices operate in relatively harsh environments, and the reliability of components is also strict. In order to meet this high-level reliability requirement, inductors mounted in digital devices on the vehicle are designed to be used in materials and product structures.

This issue introduces the LQH**PB series of inductors for in-vehicle information equipment, and also introduces the LQH32DN and LQH43NN series products that support large inductance values.

Product Design Focus As one of the design cases supporting high-standard reliability requirements, we can list its excellent structural design for conducting tests under high-intensity thermal shock. For on-board components, 1000 cycles of thermal shock testing must be performed between the minimum and maximum temperatures. Among them, the general specification for an in-vehicle information device (inductor) is -40°C↔ +105°C, and 1000 cycles of thermal shock tests must be performed at this temperature. Reducing the thermal expansion coefficient difference of the various components of the inductor is the key to complete the thermal shock test.

LQH**PB series products LQH**PB series products are wound inductors used in environments up to 105°C. This series has been manufactured in May 2012 and has been produced for 2 years. The structure of LQH**PB series is a product coated with a magnetic resin type with the purpose of winding insulating coated copper wire around the drum core to reduce the leakage of magnetic flux and protect the insulated coated copper wire to improve the strength of the product. The structure diagram is shown in Figure 1, and the product photograph is shown in Figure 2.

The selling point of the LQH**PB series products is that the optimization of the magnetic resin improves the resistance to thermal shock. By adding a material that increases the strength of the hardened coating in the magnetic resin, the possibility of cracking of the magnetic resin portion is reduced. In addition, this is a product that reduces the pressure on the drum core by approximating the difference in thermal expansion coefficient between the drum core and the magnetic resin, and at the same time, reduces the cracking of the drum core. With this resin, the resistance to thermal shock is improved, and the thermal shock test at −40° C.+105° C./1000 cycles required by the on-vehicle information equipment can be achieved. The magnetic resin and the drum core also do not crack. Product performance.

The relationship between the number of cycles invested in the thermal shock test and the incidence of cracking is shown in Figure 3. It can be seen that the magnetic resin used in the on-vehicle information equipment developed by our company has not cracked after 2000 cycles, compared with the cracking occurring in the magnetic resin for the general consumer market within 1,000 cycles. Also, it has been confirmed that thermal cracking tests conducted in a more severe environment at -40°C↔ +125°C are not cracked.