A flexible electromagnetic interference shielding film coated with a hybrid solder-magnetic powder mixture on a PET substrate

Abstract

A flexible electromagnetic interference (EMI) shielding film was innovatively fabricated using both low melting temperature solder arrays and amorphous soft magnet particulates consolidated on a polyethylene terephthalate (PET) substrate. First, the In–Sn–Bi solder arrays presented a low melting point of 99.4 °C, which enabled attachment to the heat-sensitive plastic substrate without any thermal damage, and a low electrical resistivity of 14.1 μΩ cm, making them very effective at interrupting EM waves. Second, the solder arrays with a high thermal conductivity of 61.2 W/(m·K) at 298.15 K were also useful as a thermal conductor for a heat sink. Thus, the solder arrays provide efficient electrical and thermal channels for electron transport induced by abruptly or consistently created EM waves due to suddenly turning on and the long term operation of electronics, respectively. Third, the Fe-based magnetic particulates were added and resulted in effective saturation magnetization of 161.1 emu/g, remanence of 2.9 emu/g, and coercivity of 12.5 G, thus were able to disturb the EM pathway because of their soft magnetic properties. Consequently, the hybrid EMI shielding film with exceptionally high electrical and thermal conductivity and superior soft magnetic properties provided remarkable shielding effectiveness of 102.5 dB at 10.2 GHz (X-band region). Keywords: Flexible, EMI shielding film, PET substrate, Solder arrays, Magnetic particulates