US Patent 8946560 Electric wire and coil

A electric wire includes a central conductor 1 made of aluminum or an aluminum alloy, a cover layer 2 made of copper and covering the central conductor 1, and a ferromagnetic layer 3 covering the cover layer 2 and blocking the external magnetic field. The thickness of the ferromagnetic layer 3 is in a range from 0.04 μm to 14 μm, the total diameter of the central conductor 1 and the cover layer 2 is in a range from 0.05 mm to 0.4 mm, and the cross-sectional area of the central conductor 1 is in a range from 85% to 95% of the total cross-sectional area of the central conductor 1 and the cover layer 2.