Fabrication of Magnetic Metal-Insulator Composite Film Using the LbL-Assisted Composite Plating Method

Magnetic fine particle-insulator composite films containing Fe-Ni fine particles and insulating epoxy films used for electromagnetic (EM)-wave-absorbing films were synthesized by a newly developed electrochemical method termed the “layer-by-layer (LbL)-assisted composite plating method.” A reaction solution containing water-soluble epoxy resin and Fe-Ni fine particles was used for film fabrication. Cu substrates and Ti/Pt plates were used as the cathode and the anode, respectively. In LbL-assisted composite plating, the attraction of charged Fe-Ni fine particles to the cathode by electrostatic force and electrodeposition of insulating epoxy film occurred simultaneously. LbL treatment was performed using poly(sodium 4-styrenesulfonate) (PSS) solution and poly(diallyldimethylammonium chloride) (PDDA) solution to induce negative and positive surface charge of the Fe-Ni fine particles, respectively. It is found that LbL treatment is effective for increasing charging electrons on Fe-Ni fine particles and for enhancing their dispersibility in the reaction solution. Over 39 vol.% Fe-Ni particles contained in the epoxy films were successfully obtained by using the LbL-assisted composite plating method.