The Boeing Company
Electromagnetic coil constructed from conductive traces on printed circuit boards

Abstract:

Traces, vias, or other conductive paths are formed on or through printed circuit boards or other insulating substrates to function as loops of an electromagnetic coil. The substrate itself insulates one side of each loop except at the inter-loop connection point, allowing the loops to be connected directly to each other. A ratio of trace width to depth may be selected to prevent or mitigate skin-effect losses at high operating frequencies. Nested sleeves on an insulated housing lengthen the surface distance between the coil and any nearby conductor such as an interior core or winding, presenting an effective obstacle to surface flashover between the coil and the nearby conductor. Optionally, field-shaping electrodes at the ends of the coil may discourage breakdown by reducing the electric field magnitude. Trace-based electromagnetic coils used as secondary windings in high-power transformers may be smaller than traditional wire-wound secondaries meeting similar voltage hold-off requirements.