Fabrication of highly-nanolaminated metal inductor core by pressing and punching

We present a pressing and punching method for a highly nanolaminate metal-insulator structure as a simple and cost-effective fabrication technique. The proposed nanolaminate metal-insulator structure is suitable for a magnetic core of a solenoid inductor. Cobalt-Nickel-Iron as a soft magnet metal was deposited on a polyethylene film which serves as an insulator. The Cobalt-Nickel-Iron bearing polymer film was folded multiple times and pressed with heat. The pressed sample was then comprised of multiple submicron magnetic metal layers and insulating polymer layers. The sample was cut into pieces by a punching with a predetermined shape and wire-wound for inductor application. Each nanolaminate magnetic layer suppresses the space of the eddy-current while the stacked magnetic layers will provide enough magnetic volume for the performance as an inductor. As a test vehicle, a multilayer structure of submicron Cobalt-Nickel-Iron with polyethylene film as an insulation layer was fabricated and tested. The dimension of the multilayer structure was 4 mm width, 10 mm length, and 3 mm thickness. 3000 layers in a combination of CoNiFe and polyethylene film were formed. A 10-turn with a standard magnet wire was wound to form a solenoid inductor. The test result through an impedance analyzer measurement exhibited an average inductance of 290 nH stably shown up to 100 MHz with peak quality factor of 130 at 95 MHz. The proposed method is a substrate-less process and therefore it is versatile, cost-effective, introducing easing fabrication and reducing processing time while it can achieve thousands of magnetic core layer.