Fabrication and modeling of a planar magnetic structure with directly etched windings

Methodology for directly growing three-dimensional windings on a planar, insulated ferromagnetic core through the process of electroplating and etching is presented in this paper. Designs employing high frequency inductors and transformers built in such a fashion offer tight control over parasitics from sample to sample while achieving higher power density and lower profile compared to other popular planar structures. Further, such structures are believed to be suitable as fundamental building blocks for magnetics designs with standardized cores and pre-electroplated, standardized winding patterns. They can be surface mounted on a PCB and configured by the end-user to meet his or her design specifications. To facilitate rapid design evaluation and achieve shorter design cycles, reduced-order analytical modeling based on Schwarz-Christoffel mapping and method of images for estimating parasitics of the structure is presented. The results of the models are compared against finite element modeling and experimental measurements, and are found to be acceptably accurate.