A magnetic core is situated in a cavity routed into an insulating substrate. The cavity and magnetic core are coved with a first insulating layer. Through holes are then formed through the first insulating layer and the insulating substrate, and plated to form conductive vias. Metallic traces are added to the exterior surfaces of the first insulating layer and the insulating substrate to form upper and lower winding layers. The metallic traces and conductive vias define the respective primary and secondary side windings for an embedded transformer. At least a second set of the outer conductive vias, are spaced farther from the cavity than a first set, and have greater via hole diameter than the vias in the first set. This reduces the resistance of the windings for a given substrate size and improves the performance of the device.

In one aspect, an electric coil structure is disclosed. The electric coil structure includes a magnetic core and a substrate. The substrate comprises a conductive material that is embedded in an insulating material. The substrate has a first portion and a second portion and the first portion of the substrate is wrapped around the core. The substrate can have a first portion having a plurality of contacts and a second portion having a corresponding plurality of edge contacts. The coil structure includes an alignment structure. The alignment structure can facilitate attachment of the first portion to the second portion to define a coil about the magnetic core. The alignment structure can comprise a redistribution substrate. The redistribution substrate can be disposed between the first portion and the second portion with the conductive material of the first portion electrically connected to the conductive material of the second portion through the redistribution substrate to define at least one winding. The alignment structure can include an adhesive. The adhesive can be disposed in the recess electrically connecting the first and second portions to define at least one winding. The coil structure can include a solder joint. The solder joint can be disposed between the plurality of contacts and the corresponding plurality of edge contacts making electrical connections between the first and second portions to define at least one winding such that the solder joint is exposed on the first portion.

A method of insulating a coil of a toroidal transformer, comprising forming an opening in an electrically insulating thermoplastic cup receiving an iron core with a coil for leading through terminals of the coil, arranging the iron core with the coil in the cup with the coil terminals are led out of through the opening, covering the cup with a plastic lid which engages the cup in a form-fitting manner, temporarily fixing the cup comprising the iron core and coil in an irrotatable manner, joining the cup and the lid by rotary friction by rotating welding by pressing the lid against the cup in a pressed state until the lid and the cup heat up and their material soften and become viscous due to friction, stopping the rotation of the lid within not more than one second after softening while maintaining the pressure of the lid and the cup to join their mixed material to form a continuous electrical insulation.

A transformer includes a first iron core group, a second iron core group, and winding portions. The first iron core group includes iron core stacks. The second iron core group includes iron core stacks each disposed to face a corresponding one of the iron core stacks of the first iron core group. Each of the winding portions is wound around its corresponding iron core stack of the first iron core group and its corresponding iron core stack of the second iron core group, the corresponding one iron core stack of the second iron core group facing the corresponding one iron core stack of the first iron core group. The iron core stacks of the first iron core group and the iron core stacks of the second iron core group each include annular iron cores stacked alternately.

A transformer includes a first core, a first primary coil, a first secondary coil, and a first insulating member. The first secondary coil includes a second conductor wound around the first core. The first insulating member covers the first secondary coil. The second conductor has a shape of a first polygon in a cross-section of the second conductor. A first corner of the first polygon has a first radius of curvature of 0.1 mm or more. The transformer thus has improved dielectric breakdown voltage and improved power efficiency.

A method of fabricating an inductor includes (a) forming a ferromagnetic core on a semiconductor substrate, the ferromagnetic core lying in a core plane and (b) fabricating an inductor coil that winds around the ferromagnetic core, the inductor coil configured to generate an inductor magnetic field that passes through the ferromagnetic core in a first direction parallel to the core plane. While forming the ferromagnetic core, the method further includes (1) generating a bias magnetic field that passes through the ferromagnetic core in a second direction that is orthogonal to the first direction, and (2) inducing a magnetic anisotropy in the ferromagnetic core with the bias magnetic field.

A reactor includes a toroidal coil including a winding wound to have an annular outer shape, a bus bar electrically connected to one end of the winding, and a current sensor that measures electric current flowing through the bus bar. The bus bar includes a crossing passing through a central area including an area inside an internal surface of the annular outer shape and an area in which the area extends along a central axis of the annular outer shape, and the current sensor measures electric current flowing through the crossing.

A magnetic module includes: a magnetic core; a primary coil wound on the magnetic core, the primary coil includes a first group of enameled wires and a second group of enameled wires; a secondary coil wound on the magnetic core, the secondary coil includes a third group of enameled wires and a fourth group of enameled wires, wherein the number of enameled wires of the third group of enameled wires is the same as that of the fourth group of enameled wires, the number of enameled wires of the first group is the same as that of the second group of enameled wires, and the number of the first group of enameled wires and the second group of enameled wires is greater than the number of the third group of enameled wires and the fourth group of enameled wires.

Embodiments disclosed herein include power transformers for microelectronic devices. In an embodiment, a power transformer comprises a magnetic core that is a closed loop with an inner dimension and an outer dimension, and a primary winding around the magnetic core. In an embodiment, the primary winding has a first number of first turns connected in series around the magnetic core. In an embodiment, a secondary winding is around the magnetic core, and the secondary winding has a second number of second turns around the magnetic core. In an embodiment, individual ones of the second turns comprise a plurality of secondary segments connected in parallel.

A magnetic device, such as a common-mode choke, comprising a base with a hollow stud to skewer and centre the toroidal core; and an insulating anchor with an axial bushing and a plurality of radial hooks, which is used to push the wound torpid against the base, hold the assembled device together, and insulate the windings from each other. Base and anchor are coupled and hold together through a snap-in, interlock mechanism.