Tongyou Group | Breaking Through Core Technologies in Soft Magnetic Materials to Drive the Upgrading of the Inductor Industry

2025-12-09 08:52

Soft magnetic composites represent one of the key technological barriers in the fabrication of monolithic inductors and are a primary factor influencing inductor performance. Variations in magnetic powder types, insulating coating materials and processes, as well as the incorporation of different additives, significantly affect parameters such as permeability, core losses, operating frequency, saturation current, and reliability.

Dedicated to the development of soft magnetic materials, we lay a solid foundation for quality.

Magnetic powder materials include iron powders, alloy powders, and amorphous/nanocrystalline powders. Pure iron powder is typically produced by reducing or decomposing Fe(CO)5, while alloy and amorphous/nanocrystalline powders are usually prepared via atomization, which encompasses water atomization, gas atomization, and combined water–gas atomization. Water atomization offers high production efficiency and relatively low costs; however, the resulting alloy powders exhibit poor sphericity and elevated oxygen content. Gas atomization operates on a similar principle to water atomization, enabling improved powder sphericity and reduced oxygen levels, though it entails higher manufacturing costs.

In industry, a combined water–gas atomization process is commonly employed, which leverages the advantages of both water atomization and gas atomization. The cooling rates of water atomization and gas atomization are 10^4–10^5 °C/s and 10^3–10^4 °C/s, respectively; however, this approach cannot produce spherical amorphous powders that simultaneously exhibit high saturation magnetization (Bs) and large particle sizes.

When amorphous or nanocrystalline ribbons are fractured using methods such as ball milling or air‑flow milling, the resulting powders tend to have sharp edges and corners, which is detrimental to subsequent insulating coating. Japan’s ATMIX Corporation employs a rotating water‑atomization process (SWAP) with a cooling rate exceeding 10^6 °C/s; this technique yields FeSiBC (Fe: 79–84 at.%) amorphous powders that exhibit both a large particle size (D50 > 50 μm), a high saturation magnetic flux density (Bs = 1.54–1.6 T), and excellent sphericity. In terms of preparation technologies and material properties, domestic companies now no longer lag behind their international counterparts; however, amorphous and nanocrystalline powders still fall short of those produced by ATMIX.

Dedicated to advancing magnetic materials R&D and strengthening our core commitment to quality.

Insulating coating is a key technology for soft magnetic composites and a major research focus in both academia and industry, encompassing both inorganic and organic coatings. In soft magnetic composites, insulating coating serves two critical functions:

01 Electrically insulate the metallic magnetic powder to reduce eddy current losses.

02 bonding powder, enhancing formability and the mechanical strength of magnetic powder cores.

The advantages of inorganic coating include high electrical insulation, excellent thermal stability, and superior heat resistance, enabling it to withstand prolonged high‑temperature annealing. Organic coating, on the other hand, offers good insulation and outstanding formability; however, most organic resins decompose above 300°C. Consequently, each coating technique has its own strengths, and in industrial practice, inorganic and organic coatings are typically used in combination to complement one another.

Since magnetic‑powder insulation coatings are proprietary technologies held as core trade secrets by each company, it is not possible to directly compare their performance; assessments can only be made based on inductor products.

Based on market feedback, companies in Japan, South Korea, the United States, and other regions still outperform domestic firms in insulation‑coating technology. However, in recent years, Chinese inductor manufacturers such as Majie Technology, Sunlord Electronics, Bokai New Materials, Tongyou Group, as well as magnetic‑powder producers including Antai Technology, Yue’an New Materials, Mengda New Materials, and Jinnan Magnetic Industry, have made significant progress in magnetic‑powder insulation coating.

Dedicated to advancing soft magnetic technology, we lay a solid foundation for our products.

The research and development of magnetic powder materials requires extensive technical expertise, drawing on interdisciplinary knowledge spanning materials science, physics, chemical engineering, and other fields.

Enterprises must continuously pursue technological innovation and process optimization to meet increasingly stringent performance requirements while reducing production costs. At the same time, given the diverse performance demands across various application domains, R&D teams must flexibly tailor magnetic powder materials and manufacturing processes to address these differing needs, thereby establishing distinctive technological barriers.

Tongyou Group has long been committed to the soft magnetic materials sector, having filed 14 patent applications in recent years. The company has successfully developed high‑performance soft magnetic materials characterized by low loss and high permeability. This core technological breakthrough has firmly established a robust quality foundation for the Group’s inductor products, ensuring outstanding performance across critical parameters such as stability, inductance value, and service life.