Preparation of Electroformed Copper-Nickel Multi-Nano-Layers and Characterization of Their Electromagnetic Shielding Effectiveness

Abstract

Thin copper-nickel foil with multi-nano layers was prepared by pulse-electroforming to develop a high performance electromagnetic shielding material for electronic devices. The pulse electroforming conditions of the aqueous solution chemistry were selected based on the aqueous copper-nickel-sulfur phase diagram and an evaluation of the deposition rate using the finite element method based on the current distribution in front of a cathodic electrode. The thermodynamic stability diagram revealed that the coppernickel multi-nano layers could be formed at pH<4 and ΔE>1.0 V in a modified sulfide bath. The electro-formed copper-nickel multi-layer was well produced at the pulse plating conditions of –0.2V_SHE, –0.5 mA/cm², and 25 seconds for copper layer and –1.7 V_SHE, –50 mA/cm² and 80 seconds for nickel layer, which was composed of about 25 nm thick copper and about 30 nm thick nickel rich phases, respectively. The average deposition rate of the copper-nickel foil with multi-nano layers was estimated by the finite element method to be about 0.115 mm/sec, which was in good agreement with the real value of the thin multi-nano layered copper-nickel foil. The effectiveness of the electromagnetic shielding of the copper-nickel mesh with multi-nano layers was more than 30% higher than that of copper mesh in the frequency range of 8.2 and 12.5 GHz.