Signal Transformer application engineers are often asked when a designer should specify a shielded inductor over an un-shielded one. Once current is applied to an inductor, a magnetic flux field is generated, radiating from the part, and can couple with adjacent components or circuitry. With a shielded power inductor, the majority of this magnetic flux is kept inside the package, safely confined. In an un-shielded power inductor the magnetic flux field radiates freely and may cause operational problems. Here are some other considerations: if un-shielded and shielded power inductors have the same inductance value in the same volumetric size, then the un-shielded structures would need more winding turns to achieve the same inductance value, so the DC resistance of their windings is higher.