Pukyong National University

Pukyong National University and Japan’s AIST Jointly Develop Iron-Copper-Silver Composite Powder with Ferromagnetism and High Electrical Conductivity

- Korea-Japan joint research achievement … Expected to be used as a conductive filler for semiconductor test sockets

- Superior electrical conductivity compared with conventional nickel powder demonstrated … Patent applications underway in Korea and abroad

Pukyong National University and Japan’s National Institute of Advanced Industrial Science and Technology (AIST) have jointly developed an iron (Fe)-copper (Cu)-silver (Ag) composite powder that combines ferromagnetism with high electrical conductivity through international collaborative research.

As demand for high-performance conductive materials continues to grow with the miniaturization of semiconductors and the increasing number of pins, the newly developed material is expected to have potential applications as a conductive filler for next-generation semiconductor test sockets.

Professor Han-Sang Kwon’s research team in the Major of Materials System Engineering at Pukyong National University jointly developed the Fe-Cu-Ag composite powder with researchers including Dr. Kwang-Jae Park of AIST’s Multi-Materials Research Institute and characterized its magnetic, electrical, and mechanical properties. The research findings were presented on September 11 at the 87th Autumn Meeting of the Japan Society of Applied Physics in Sapporo, Japan.

The research team produced the Fe-Cu-Ag composite powder by combining ferromagnetic Fe with Cu and Ag, both of which have high electrical conductivity. In particular, the team designed an Fe:Cu:Ag mass ratio of 3:5:2 and applied gas atomization and thermal plasma methods to synthesize micro-composite powder with an average particle size of approximately 50 μm and nano-composite powder of approximately 100 nm, respectively.

The developed composite powders exhibited higher electrical conductivity than nickel (Ni) powder, which is widely used in conventional semiconductor test sockets. Their saturation magnetization, a measure of the maximum magnetization a material can attain, was also higher than or comparable to that of Ni (approximately 57 emu/g), reaching approximately 63 emu/g for the micro-composite powder and 56 emu/g for the nano-composite powder.

The micro-composite powder also recorded a Vickers hardness of 127 HV, higher than the 100-110 HV of Ni powder, demonstrating its potential for superior mechanical properties as well.

The key to this study lies in utilizing the immiscible nature of Fe, Cu, and Ag to create a composite microstructure in which Fe provides magnetic functionality, while Cu and Ag provide high electrical conductivity. In the micro-composite powder, Fe and Cu were dispersed within an Ag-based matrix, while the nano-composite powder formed a structure in which Fe was concentrated at the center of the particles, with Cu and Ag distributed toward the outer regions.

These properties are expected to make the material suitable for use as a conductive filler in elastomer-based semiconductor test sockets. Because conductive fillers provide the electrical connection between semiconductor terminals and testing equipment, they require not only high electrical conductivity but also appropriate mechanical strength and durability. In particular, the use of ferromagnetic materials makes it possible to apply a magnetic field during manufacturing to align conductive particles in the desired direction.

Professor Han-Sang Kwon said, “This study presents a new material design strategy that can overcome the limitations of conventional materials by combining the ferromagnetism of Fe with the high electrical conductivity of Cu and Ag in a single composite powder. Going forward, we plan to expand its potential applications beyond semiconductor test sockets to a wide range of electronic and electrical materials in which conductive pathways can be controlled using magnetic fields.”

The research team plans to optimize the powder’s composition, particle size, and microstructure for application in actual silicone rubber-based test sockets and evaluate its contact resistance, durability under repeated use, and signal transmission characteristics. Patent applications for the technology are currently underway in Korea and abroad, and the team plans to pursue its commercialization for materials used in semiconductor testing processes.