High current magnetic component and methods of manufacture

Magnetic components including pre-formed clips are described that are more amenable to production on a miniaturized scale. Discrete core pieces can be assembled with pre-formed coils and physically gapped from one another with more efficient manufacturing techniques.

TECHNICAL FIELD

The invention relates generally to electronic components and methods of manufacturing these components and, more particularly, to inductors, transformers, and the methods of manufacturing such items.

BACKGROUND

Typical inductors may include toroidal cores and shaped-cores, including a shield core and drum core, U core and I core, E core and I core, and other matching shapes. The typical core materials for these inductors are ferrite or normal powder core materials, which include iron (Fe), Sendust (Al—Si—Fe), MPP (Mo—Ni—Fe), and HighFlux (Ni—Fe). The inductors typically have a conductive winding wrapped around the core, which may include, but is not limited to a magnet wire coil that may be flat or rounded, a stamped copper foil, or a clip. The coil may be wound on the drum core or other bobbin core directly. Each end of the winding may be referred to as a lead and is used for coupling the inductor to an electrical circuit. The winding may be preformed, semi-preformed, or non-preformed depending upon the application requirements. Discrete cores may be bound together through an adhesive.

With the trend of power inductors going toward higher current, a need exists for providing inductors having more flexible form factors, more robust configurations, higher power and energy densities, higher efficiencies, and tighter inductance and Direct Current Resistance (“DCR”) tolerance. DC to DC converters and Voltage Regulator Modules (“VRM”) applications often require inductors having tighter DCR tolerances, which is currently difficult to provide due to the finished goods manufacturing process. Existing solutions for providing higher saturation current and tighter tolerance DCR in typical inductors have become very difficult and costly and do not provide the best performance from these typical inductors. Accordingly, the current inductors are in need for such improvements.

To improve certain inductor characteristics, toroidal cores have recently been manufactured using an amorphous powder material for the core material. Toroidal cores require a coil, or winding, to be wound onto the core directly. During this winding process, the cores may crack very easily, thereby causing the manufacturing process to be difficult and more costly for its use in surface-mount technology. Additionally, due to the uneven coil winding and coil tension variations in toroidal cores, the DCR is not very consistent, which is typically required in DC to DC converters and VRM. Due to the high pressures involved during the pressing process, it has not been possible to manufacture shaped-cores using amorphous powder materials.

Due to advancements in electronic packaging, the trend has been to manufacture power inductors having miniature structures. Thus, the core structure must have lower and lower profiles so that they may be accommodated by the modern electronic devices, some of which may be slim or have a very thin profile. Manufacturing inductors having a low profile has caused manufactures to encounter many difficulties, thereby making the manufacturing process expensive.

For example, as the components become smaller and smaller, difficulty has arisen due to the nature of the components being hand wound. These hand wound components provide for inconsistencies in the product themselves. Another encountered difficulty includes the shape-cores being very fragile and prone to core cracking throughout the manufacturing process. An additional difficulty is that the inductance is not consistent due to the gap deviation between the two discrete cores, including but not limited to drum cores and shielded cores, ER cores and I cores, and U cores and I cores, during assembly. A further difficulty is that the DCR is not consistent due to uneven winding and tension during the winding process. These difficulties represent examples of just a few of the many difficulties encountered while attempting to manufacture inductors having a miniature structure.

Manufacturing processes for inductors, like other components, have been scrutinized as a way to reduce costs in the highly competitive electronics manufacturing business. Reduction of manufacturing costs is particularly desirable when the components being manufactured are low cost, high volume components. In a high volume component, any reduction in manufacturing cost is, of course, significant. It may be possible that one material used in manufacturing may have a higher cost than another material. However, the overall manufacturing cost may be less by using the more costly material because the reliability and consistency of the product in the manufacturing process is greater than the reliability and consistency of the same product manufactured with the less costly material. Thus, a greater number of actual manufactured products may be sold, rather than being discarded. Additionally, it also is possible that one material used in manufacturing a component may have a higher cost than another material, but the labor savings more than compensates for the increase in material costs. These examples are just a few of the many ways for reducing manufacturing costs.

It has become desirable to provide a magnetic component having a core and winding configuration that can allow one or more of the following improvements, a more flexible form factor, a more robust configuration, a higher power and energy density, a higher efficiency, a wider operating frequency range, a wider operating temperature range, a higher saturation flux density, a higher effective permeability, and a tighter inductance and DCR tolerance, without substantially increasing the size of the components and occupying an undue amount of space, especially when used on circuit board applications. It also has become desirable to provide a magnetic component having a core and winding configuration that can allow low cost manufacturing and achieves more consistent electrical and mechanical properties. Furthermore, it is desirable to provide a magnetic component that tightly controls the DCR over large production lot sizes.

SUMMARY

A magnetic component and a method of manufacturing such a component is described. The magnetic component may include, but is not limited to, an inductor or a transformer. The method comprises the steps of providing at least one shaped-core fabricated from an amorphous powder material, coupling at least a portion of at least one winding to the at least one shaped-core, and pressing the at least one shaped-core with at least a portion of the at least one winding. The magnetic component comprises at least one shaped-core fabricated from an amorphous powder material and at least a portion of at least one winding coupled to the at least one shaped-core, wherein the at least one shaped-core is pressed to at least a portion of the at least one winding. The winding may be preformed, semi-preformed, or non-preformed and may include, but is not limited to, a clip or a coil. The amorphous powder material may be an iron-based amorphous powder material or a nanoamorphous powder material.

According to some aspects, two shaped-cores are coupled together with a winding positioned there between. In these aspects, one of the shaped-cores is pressed, and the winding is coupled to the pressed shaped-core. The other shaped-core is coupled to the winding and the pressed shaped-core and pressed again to form the magnetic component. The shaped-core may be fabricated from an amorphous powder material or a nanoamorphous powder material.

According to other exemplary aspects, the amorphous powder material is coupled around at least one winding. In these aspects, the amorphous powder material and the at least one winding are pressed together to form the magnetic component, wherein the magnetic component has a shaped-core. According to these aspects, the magnetic component may have a single shaped-core and a single winding, or it may comprise a plurality of shaped-cores within a single structure, wherein each of the shaped-cores has a corresponding winding. Alternatively, the shaped-core may be fabricated from a nanoamorphous powder material.

These and other aspects, objects, features, and advantages of the invention will become apparent to a person having ordinary skill in the art upon consideration of the following detailed description of illustrated exemplary embodiments, which include the best mode of carrying out the invention as presently perceived.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring toFIGS. 1-5, several views of various illustrative, exemplary embodiments of a magnetic component or device are shown. In an exemplary embodiment the device is an inductor, although it is appreciated that the benefits of the invention described below may accrue to other types of devices. While the materials and techniques described below are believed to be particularly advantageous for the manufacture of low profile inductors, it is recognized that the inductor is but one type of electrical component in which the benefits of the invention may be appreciated. Thus, the description set forth is for illustrative purposes only, and it is contemplated that benefits of the invention accrue to other sizes and types of inductors, as well as other electronic components, including but not limited to transformers. Therefore, practice of the inventive concepts herein is not limited solely to the exemplary embodiments described herein and illustrated in the figures. Additionally, it is understood that the figures are not to scale, and that the thickness and other sizes of the various components have been exaggerated for the purpose of clarity.

FIG. 1illustrates a perspective view of a power inductor having an ER-I shaped-core during multiple stages in the manufacturing process, in accordance with an exemplary embodiment. In this embodiment, the power inductor100comprises an ER core110, a preformed coil130, and an I core150.

The ER core110is generally square or rectangular in shape and has a base112, two side walls114,115, two end walls120,121, a receptacle124, and a centering projection or post126. The two side walls114,115extend the entire longitudinal length of the base112and have an exterior surface116and an interior surface117, wherein the interior surface117is proximate to the centering projection126. The exterior surface116of the two side walls114,115are substantially planar, while the interior surface117of the two side walls are concave. The two end walls120,121extend a portion of the width of the base112from the ends of each side wall114,115of the base112, such that a gap122,123is formed in each of the two end walls120,121, respectively. This gap122,123may be formed substantially in the center of each of the two end walls120,121such that the two side walls114,115are mirror images of one another. The receptacle124is defined by the two side walls114,115and the two end walls120,121. The centering projection126may be centrally located in the receptacle124of the ER core110and may extend upwardly from the base112of the ER core110. The centering projection126may extend to a height that is substantially the same as the height of the two side walls114,115and the two end walls120,121, or the height may extend less than the height of the two side walls114,115and the two end walls120,121. As such, the centering projection126extends into an inner periphery132of the preformed coil130to maintain the preformed coil130in a fixed, predetermined, and centered position with respect to the ER core110. Although the ER core is described as having a symmetrical core structure in this embodiment, the ER core may have an asymmetrical core structure without departing from the scope and spirit of the exemplary embodiment.

The preformed coil130has a coil having one or more turns, and two terminals134,136, or leads, that extend from the preformed coil130at 180° from one another. The two terminals134,136extend in an outwardly direction from the preformed coil130, then in an upward direction, and then back in an inward direction towards the preformed coil130; thereby each forming a U-shaped configuration. The preformed coil130defines the inner periphery132of the preformed coil130. The configuration of the preformed coil130is designed to couple the preformed coil130to the ER core110via the centering projection126, such that the centering projection126extends into the inner periphery132of the preformed coil130. The preformed coil130is fabricated from copper and is plated with nickel and tin. Although the preformed coil130is made from copper and has nickel and tin plating, other suitable conductive materials, including but not limited to gold plating and soldering, may be utilized in fabricating the preformed coil130and/or the two terminals134,136without departing from the scope and spirit of the invention. Additionally, although a preformed coil130has been depicted as one type of winding that may be used within this embodiment, other types of windings may be utilized without departing from the scope and spirit of the invention. Additionally, although this embodiment utilizes a preformed coil130, semi-preformed windings, and non-preformed windings may also be used without departing from the scope and spirit of the invention. Further, although the terminals134,136have been described in a particular configuration, alternative configurations may be used for the terminals without departing from the scope and spirit of the invention. Moreover, the geometry of the preformed coil130may be circular, square, rectangular, or any other geometric shape without departing from the scope and spirit of the invention. The interior surface of the two side walls114,115and the two end walls120,121may be reconfigured accordingly to correspond to the geometry of the preformed coil130, or winding. In the event the coil130has multiple turns, insulation between the turns may be required. The insulation may be a coating or other type of insulator that may be placed between the turns.

The I core150is generally square or rectangular in shape and substantially corresponds to the footprint of the ER core110. The I core150has two opposing ends152,154, wherein each end152,154has a recessed portion153,155, respectively, to accommodate an end portion of the terminals134,136. The recessed portions153,155are substantially the same width, or slightly larger in width, when compared to the width of the end portion of the terminals134,136.

In an exemplary embodiment, the ER core110and the I core150are both fabricated from an amorphous powder core material. According to some embodiments, the amorphous powder core material can be an iron-based amorphous powder core material. One example of the iron-based amorphous powder core material comprises approximately 80% iron and 20% other elements. According to alternative embodiments, the amorphous powder core material can be a cobalt-based amorphous powder core material. One example of the cobalt-based amorphous powder core material comprises approximately 75% cobalt and 25% other elements. Still, according to some other alternative embodiments, the amorphous powder core material can be a nanoamorphous powder core material.

This material provides for a distributed gap structure, wherein the binder material behaves as gaps within the fabricated iron-based amorphous powder material. An exemplary material is manufactured by Amosense in Seoul, Korea and sold under product number APHxx (Advanced Powder Core), where xx represents the effective permeability of the material. For example, if the effective permeability for the material is 60, the part number is APH60. This material is capable of being used for high current power inductor applications. Additionally, this material may be used with higher operating frequencies, typically in the range of about 1 MHz to about 2 MHz, without producing abnormal heating of the inductor100. Although the material may be used in the higher frequency range, the material may be used in lower and higher frequency ranges without departing from the scope and spirit of the invention. The amorphous powder core material can provide a higher saturation flux density, a lower hysteresis core loss, a wider operating frequency range, a wider operating temperature range, better heat dissipation and a higher effective permeability. Additionally, this material can provide for a lower loss distributed gap material, which thereby can maximize the power and energy density. Typically, the effective permeability of shaped-cores is not very high due to pressing density concerns. However, use of this material for the shaped-cores can allow a much higher effective permeability than previously available. Alternatively, the nanoamorphous powder material can allow up to three times higher permeability when compared to the permeability of an iron-based amorphous powder material.

As illustrated inFIG. 1, the ER core110and the I core150are pressed molded from amorphous powder material to form the solid shaped-cores. Upon pressing the ER core110, the preformed coil130is coupled to the ER core110in the manner previously described. The terminals134,136of the preformed coil130extend through the gaps122,123in the two end walls120,121. The I core150is then coupled to the ER core110and the preformed coil130such that the ends of the terminals134,136are coupled within the recessed portions153,155, respectively, of the I core150. The ER core110, the preformed coil130, and the I core150are then pressed molded together to form the ER-I inductor100. Although the I core150has been illustrated as having recessed portions153,155formed in the two opposing ends152,154, the I core150may have the recessed portions omitted without departing from the scope and spirit of the invention. Also, although the I core150has been illustrated to be symmetrical, asymmetrical I cores may be used, including I cores having mistake proofing, as described below, without departing from the scope and spirit of the invention.

FIG. 2illustrates a perspective view of a power inductor having a U-I shaped-core, during multiple stages in the manufacturing process, in accordance with an exemplary embodiment. In this embodiment, the power inductor200comprises a U core210, a preformed clip230, and an I core250. As used herein and throughout the specification, the U core210has two sides212,214and two ends216,218, wherein the two sides212,214are parallel with respect to the orientation of the winding, or clip,230and the two ends216,218are perpendicular with respect to the orientation of the winding, or clip230. Additionally, the I core250has two sides252,254and two ends256,260, wherein the two sides252,254are parallel with respect to the orientation of the winding, or clip,230and the two ends256,260are perpendicular with respect to the orientation of the winding, or clip230. According to this embodiment, the I core250has been modified to provide for a mistake proof I core250. The mistake proof I core250has removed portions257,261from two parallel ends256,260, respectively at one side252of the bottom251of the mistake proof I core250and non-removed portions258,262from the same two parallel ends256,260, respectively, at the opposing side254of the mistake proof I core250.

The preformed clip230has two terminals234,236, or leads, that may be coupled around the mistake proof I core250by positioning the preformed clip230at the removed portions257,261and sliding the preformed clip230towards the non-removed portions258,262until the preformed clip230may not be moved further. The preformed clip230can allow better DCR control, when compared to a non-preformed clip, because bending and cracking of platings is greatly reduced in the manufacturing process. The mistake proof I core250enables the preformed clip230to be properly positioned so that the U core210may be quickly, easily, and correctly coupled to the mistake proof I core250. As shown inFIG. 2, only the bottom251of the mistake proof I core250provides the mistake proofing. Although only the bottom251of the mistake proof I core250provides the mistake proofing in this embodiment, alternative sides, either alone or in combination with another side, may provide the mistake proofing without departing from the scope and spirit of the exemplary embodiment. For example, the mistake proofing may be located only at the opposing ends256,260or at the opposing ends256,260and the bottom251of the I core, instead of only at the bottom251of the I core250as depicted inFIG. 2. Additionally, the I core250may be formed without any mistake proofing according some alternative embodiments.

The preformed clip230is fabricated from copper and is plated with nickel and tin. Although the preformed clip230is made from copper and has nickel and tin plating, other suitable conductive materials, including but not limited to gold plating and soldering, may be utilized in fabricating the preformed clip230and/or the two terminals234,236without departing from the scope and spirit of the invention. Additionally, although a preformed clip230is used in this embodiment, the clip230may be partially preformed or not preformed without departing from the scope and spirit of the invention. Furthermore, although a preformed clip230is depicted in this embodiment, any form of winding may be used without departing from the scope and spirit of the invention.

The removed portions257,261from the mistake proof I core250may be dimensioned such that a symmetrical U core or an asymmetrical U core, which are described with respect toFIG. 3AandFIG. 3Brespectively, may be utilized without departing from the scope and spirit of the invention. The U core210is dimensioned to have a width substantially the same as the width of the mistake proof I core250and a length substantially the same as the length of the mistake proof I core250. Although the dimensions of the U core210have been illustrated above, the dimensions may be altered without departing from the scope and spirit of the invention.

FIG. 3Aillustrates a perspective view of a symmetrical U core in accordance with an exemplary embodiment. The symmetrical U core300has one surface310and an opposing surface320, wherein the one surface310is substantially planar, and the opposing surface320has a first leg322, a second leg324, and a clip channel326defined between the first leg322and the second leg324. In the symmetrical U core300, the width of the first leg322is substantially equal to the width of the second leg324. This symmetrical U core300is coupled to the I core250, and a portion of the preformed clip230is positioned within the clip channel326. According to certain exemplary embodiments, the terminals234,236of the preformed clip230are coupled to the bottom surface251of the I core250. However, in alternative exemplary embodiments, the terminals234,236of the preformed clip230may be coupled to the one surface310of the U core300.

FIG. 3Billustrates a perspective view of an asymmetrical U core in accordance with an exemplary embodiment. The asymmetrical U core350has one surface360and an opposing surface370, wherein the one surface360is substantially planar, and the opposing surface370has a first leg372, a second leg374, and a clip channel376defined between the first leg372and the second leg374. In the asymmetrical U core350, the width of the first leg372is not substantially equal to the width of the second leg374. This asymmetrical U core350is coupled to the I core250, and a portion of the preformed clip230is positioned within the clip channel376. According to certain exemplary embodiments, the terminals234,236of the preformed clip230are coupled to the bottom surface251of the I core250. However, in alternative exemplary embodiments, the terminals234,236of the preformed clip230may be coupled to the one surface360of the U core350. One reason for using an asymmetrical U core350is to provide a more even flux density distribution throughout the entire magnetic path.

In an exemplary embodiment, the U core210and the I core250are both fabricated from an amorphous powder core material, which is the same material as described above in reference to the ER core110and the I core150. According to some embodiments, the amorphous powder core material can be an iron-based amorphous powder core material. Additionally, a nanoamorphous powder material may also be used for these core materials. As illustrated inFIG. 2, the preformed clip230is coupled to the I core250, and the U core210is coupled to the I core250and the preformed clip230such that the preformed clip230is positioned within the clip channel of the U core210. The U core210can be symmetrical as shown with U core310or asymmetrical as shown with U core350. The U core210, the preformed clip230, and the I core250are then pressed molded together to form the UI inductor200. The press molding removes the physical gap that is generally located between the preformed clip230and the core210,250by having the cores210,250form molded around the preformed clip230.

FIG. 4illustrates a perspective view of a power inductor having a bead core in accordance with an exemplary embodiment. In this embodiment, the power inductor400comprises a bead core410and a semi-preformed clip430. As used herein and throughout the specification, the bead core410has two sides412,414and two ends416,418, wherein the two sides412,414are parallel with respect to the winding, or clip,430and the two ends416,418are perpendicular with respect to the winding, or clip430.

In an exemplary embodiment, the bead core410is fabricated from an amorphous powder core material, which is the same material as described above in reference to the ER core110and the I core150. According to some embodiments, the amorphous powder core material can be an iron-based amorphous powder core material. Additionally, a nanoamorphous powder material may also be used for these core materials.

The semi-preformed clip430comprises two terminals, or leads,434,436at opposing two ends416,418and may be coupled to the bead core410by having a portion of the semi-preformed clip430pass centrally within the bead core410and having the two terminals434,436wrap around the two ends416,418of the bead core410. The semi-preformed clip430can allow better DCR control, when compared to a non-preformed clip, because bending and cracking of platings is greatly reduced in the manufacturing process.

The semi-preformed clip430is fabricated from copper and is plated with nickel and tin. Although the semi-preformed clip430is made from copper and has nickel and tin plating, other suitable conductive materials, including but not limited to gold plating and soldering, may be utilized in fabricating the semi-preformed clip430without departing from the scope and spirit of the invention. Additionally, although a semi-preformed clip430is used in this embodiment, the clip430may be not preformed without departing from the scope and spirit of the invention. Furthermore, although a semi-preformed clip430is depicted in this embodiment, any form of winding may be used without departing from the scope and spirit of the invention.

As illustrated inFIG. 4, the semi-preformed clip430is coupled to the bead core410by having a portion of the semi-preformed clip430pass within the bead core410and having the two terminals434,436wrap around the two ends416,418of the bead core410. In some embodiments, the bead core410can be modified to have a removed portion440from one side412of the bottom450of the bead core410and a non-removed portion442from the opposing side414of the bead core410. The two terminals434,436of the semi-preformed clip430can be positioned at the bottom450of the bead core410such that the terminals434,436are located within the removed portion442. Although the bead core has been illustrated having a removed portion and a non-removed portion, the bead core may be formed to omit the removed portion without departing from the scope and spirit of the invention.

According to an exemplary embodiment, the amorphous powder core material may be initially formed into a sheet and then wrapped or rolled around the semi-preformed clip430. Upon rolling the amorphous powder core material around the semi-preformed clip430, the amorphous powder core material and the semi-preformed clip430can then be pressed at high pressures, thereby forming the power inductor400. The press molding removes the physical gap that is generally located between the semi-preformed clip430and the bead core410by having the bead core410form molded around the semi-preformed clip430.

According to another exemplary embodiment, the amorphous powder core material and the semi-preformed clip430may be positioned within a mold (not shown), such that the amorphous powder core material surrounds at least a portion of the semi-preformed clip430. The amorphous powder core material and the semi-preformed clip430can then be pressed at high pressures, thereby forming the power inductor400. The press molding removes the physical gap that is generally located between the semi-preformed clip430and the bead core410by having the bead core410form molded around the semi-preformed clip430.

Additionally, other methods may be used to form the inductor described above. In a first alternative method, a bead core may be formed by pressing the amorphous powder core material at high pressures, followed by coupling the winding to the bead core, and then followed by adding additional amorphous powder core material to the bead core so that the winding is disposed between the bead core and at least a portion of the additional amorphous powder core material. The bead core, the winding and the additional amorphous powder core material are then pressed together at high pressures to form the power inductor described in this embodiment. In a second alternative method, two discrete shaped cores may be formed by pressing the amorphous powder core material at high pressures, followed by positioning the winding between the two discrete shaped cores, and then followed by adding additional amorphous powder core material. The two discrete shaped cores, the winding, and the additional amorphous powder core material are then pressed together at high pressures to form the power inductor described in this embodiment. In a third alternative method, injection molding can be used to mold the amorphous powder core material and the winding together. Although a bead core is described in this embodiment, other shaped cores may be utilized without departing from the scope and spirit of the exemplary embodiment.

FIG. 5illustrates a perspective view of a power inductor having a plurality of U shaped-cores formed as a single structure in accordance with an exemplary embodiment. In this embodiment, the power inductor500comprises four U shaped-cores510,515,520,525formed as a single structure505and four clips530,532,534,536, wherein each clip530,532,534,536is coupled to a respective one of the U shaped-core510,515,520,525and wherein each clip530,532,534,536is not preformed. As used herein and throughout the specification, the inductor500has two sides502,504and two ends506,508, wherein the two sides502,504are parallel with respect to the windings, or clips,530,532,534,536, and the two ends506,508are perpendicular with respect to the windings, or clips,530,532,534,536. Although four U cores510,515,520,525and four clips530,532,534,536are shown to form a single structure505, greater or fewer U cores, with a corresponding number of clips, may be used to form the single structure without departing from the scope and spirit of the invention.

In an exemplary embodiment, the core material is fabricated from an iron-based amorphous powder core material, which is the same material as described above in reference to the ER core110and the I core150. Additionally, a nanoamorphous powder material may also be used for these core materials.

Each clip530,532,534,536has two terminals, or leads,540(not shown),542at opposing ends and may be coupled to each of the U shaped-cores510,515,520,525by having a portion of the clip530,532,534,536pass centrally within each of the U shaped-cores510,515,520,525and having the two terminals540(not shown),542of each clip530,532,534,536wrap around the two ends506,508of the inductor500.

The clips530,532,534,536are fabricated from copper and are plated with nickel and tin. Although the clips530,532,534,536are made from copper and has nickel and tin plating, other suitable conductive materials, including but not limited to gold plating and soldering, may be utilized in fabricating the clips without departing from the scope and spirit of the invention. Additionally, although the clips530,532,534,536are depicted in this embodiment, any form of windings may be used without departing from the scope and spirit of the invention.

As illustrated inFIG. 5, the clips530,532,534,536are coupled to the U shaped-cores510,515,520,525by having a portion of each of the clips530,532,534,536pass within each of the U shaped-cores510,515,520,525and having the two terminals540(not shown),542of each preformed clip530,532,534,536wrap around the two ends506,508of the inductor500.

According to an exemplary embodiment, the amorphous powder core material may be initially formed into a sheet and then wrapped around the clips530,532,534,536. Upon wrapping the amorphous powder core material around the clips530,532,534,536, the amorphous powder core material and the clips530,532,534,536can then be pressed at high pressures, thereby forming the U-shaped inductor500having a plurality of U shaped-cores510,515,520,525formed as a single structure505. The press molding removes the physical gap that is generally located between the clips530,532,534,536and the cores510,515,520,525by having the cores510,515,520,525form molded around the clips530,532,534,536.

According to another exemplary embodiment, the amorphous powder core material and the clips530,532,534,536may be positioned within a mold (not shown), such that the amorphous powder core material surrounds at least a portion of the clips530,532,534,536. The amorphous powder core material and the clips530,532,534,536can then be pressed at high pressures, thereby forming the U-shaped inductor500having a plurality of U shaped-cores510,515,520,525formed as a single structure505. The press molding removes the physical gap that is generally located between the clips530,532,534,536and the cores510,515,520,525by having the cores510,515,520,525form molded around the clips530,532,534,536.

Additionally, other methods may be used to form the inductor described above. In a first alternative method, a plurality of U-shaped cores may be formed together by pressing the amorphous powder core material at high pressures, followed by coupling the plurality of windings to each of the plurality of U-shaped cores, and then followed by adding additional amorphous powder core material to the plurality of U-shaped cores so that the plurality of windings are disposed between the plurality of U-shaped cores and at least a portion of the additional amorphous powder core material. The plurality of U-shaped cores, the plurality of windings, and the additional amorphous powder core material are then pressed together at high pressures to form the inductor described in this embodiment. In a second alternative method, two discrete shaped cores, wherein each discrete shaped core has a plurality of shaped cores coupled together, may be formed by pressing the amorphous powder core material at high pressures, followed by positioning the plurality of windings between the two discrete shaped cores, and then followed by adding additional amorphous powder core material. The two discrete shaped cores, the plurality of windings, and the additional amorphous powder core material are then pressed together at high pressures to form the inductor described in this embodiment. In a third alternative method, injection molding can be used to mold the amorphous powder core material and the plurality of windings together. Although a plurality of U-shaped cores are described in this embodiment, other shaped cores may be utilized without departing from the scope and spirit of the exemplary embodiment.

Additionally, the plurality of clips530,532,534,536may be connected in parallel to each other or in series based upon circuit connections on a substrate (not shown) and depending upon application requirements. Furthermore, these clips530,532,534,536may be designed to accommodate multi-phase current, for example, three-phase and four-phase.

Although several embodiments have been disclosed above, it is contemplated that the invention includes modifications made to one embodiment based upon the teachings of the remaining embodiments.

While single piece core constructions fabricated from distributed gap magnetic materials and one or more coils arranged in the single piece core construction is advantageous in certain applications, in other applications still other benefits may be realized using discrete core pieces assembled with one or more coils and incorporating physical gaps can provide desirable performance advantages. Structures and methods of accomplishing assembly of discrete core pieces and physical gaps are described further below.

FIGS. 6-9illustrate another magnetic component assembly600at various stages of manufacture. As shown inFIG. 6, the assembly includes a first magnetic core piece602and winding604forming a first subassembly.

In the exemplary embodiment shown, the magnetic core piece602is an I Core having an elongated rectangular block or brick shape. The magnetic core piece602may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art.

Also in the exemplary embodiment shown, the winding604is provided in the form of a pre-formed winding clip having an elongated, generally flat and planar main winding section606and opposing leg sections608and610extending from either end of the main winding section606. The legs608and610extend generally perpendicularly from the plane of the main winding section604in a substantially C-shaped arrangement. The pre-formed winding clip604further includes terminal lead sections612,614extending from each of the respective legs608and610. The terminal lead sections612,614extend generally perpendicular to the respective planes of the legs608and610and generally parallel to a plane of the main winding section606. The terminal lead sections612,614provide spaced apart contact pads for surface mounting to a circuit board (not shown). The clip604and its sections606,608,610,612and614collectively form a body or frame defining an interior region or cavity616. In the exemplary embodiment shown, the cavity616is substantially rectangular and complementary in shape to the first magnetic core piece602.

In exemplary embodiments, the clip604may be fabricated from a sheet of copper or other conductive material or alloy and may and formed into the shape as shown using known techniques, including but not limited to stamping and pressing techniques. In an exemplary embodiment, the clip604is separately fabricated and provided for assembly to the core piece602, referred to here as being a pre-formed coil610. Such a pre-formed coil604is specifically contrasted with conventional magnetic component assemblies wherein the coil is formed about a core piece, or otherwise is bent or shaped around a core piece.

As shown inFIG. 7the clip604and the first magnetic core piece602are assembled or otherwise coupled to one another to form a first subassembly620. In one embodiment the core piece602could be fabricated independently from the clip604and the core piece602is fitted into the cavity616of the clip604to complete the subassembly with, for example, sliding engagement. In another embodiment, the core piece602could be formed in the cavity616using a pressing or molding process, for example. However formed, in the exemplary embodiment shown, the core piece602is sized and shaped to be substantially coextensive with the cavity616of the clip604. That is, the core piece602substantially fills the cavity616, but does not project from the cavity616of the clip604. In other words, the magnetic core piece602is generally self-contained in the interior confines of the clip, and the external dimensions of the core and clip assembly shown inFIG. 7is equal to the external dimensions of the clip604itself before assembly with the core piece602.

AsFIG. 7illustrates, each section606,608,610,612,614of the clip604physically abuts or engages a different side surface or face of the magnetic core piece602. The core piece602is securely received and cradled within the clip604such that the subassembly620may be moved as a unit in further assembly steps of magnetic components.

FIG. 8illustrates the subassembly620ofFIG. 7being assembled with a second magnetic core piece630. The second magnetic core piece630may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art. Furthermore, the second magnetic core piece630in various embodiments may be fabricated from the same or different magnetic material than used to fabricate the first core piece602. That is, if desired, the first and second magnetic core pieces602,630may exhibit different magnetic materials or the same magnetic materials depending on the particular materials chosen.

In the exemplary embodiment shown, the second magnetic core piece630is a U core having a U shape including a substantially planar surface632and a surface634opposing the planar surface632that includes a first leg636, a second leg638, and a clip channel640defined between the first and second legs636and638. In different embodiments, symmetrical and asymmetrical U-cores may be utilized as described above. The subassembly620including the first core piece602and the clip604is aligned with and inserted in the clip channel640as shown inFIG. 8such that the subassembly620is inter-fitted with the core piece630. As such, the subassembly620extends axially through the second core piece630for substantially an entire axial distance between opposing ends642,644of the second core piece630. That is, the leg sections608,610(FIG. 6) of the clip lie generally adjacent and substantially flush or coplanar with the ends642,644of the second core piece630. When so assembled, the first and second core pieces602,630may be bonded together with adhesives and the like.

As shown in the completed component600inFIG. 9, the terminal lead sections612,614are exposed and substantially flush or coplanar with the bottom surface of the second core piece630and hence are well situated for surface mount, electrical connection to a circuit board. Additionally, and as shown inFIG. 9, physical gaps650may be formed between the core pieces602and630and may provide desirable performance characteristics for a power inductor, and potentially for other types of magnetic components in other embodiments. In the embodiment shown, the gaps650extend axially on either side of the subassembly620within the clip channel640(FIG. 8) in the second magnetic core piece630. The size of the gaps650may be varied by adjusting the dimensions of the clip channel640(FIG. 8) in the second core piece630and/or the dimension of the subassembly620that includes the first core piece602. By varying the dimensions of the gaps, the performance characteristics of the resultant magnetic component may be varied to meet particular objectives and provide a variety of power inductors, for example, having different performance characteristics in a uniform package size and with relatively easy and efficient manufacturing step compared to conventional magnetic components.

While a single coil embodiment has been described in relation toFIGS. 6-9, it is recognized that multiple coil embodiments are possible in further and/or alternative embodiments.

FIGS. 10-13illustrate another magnetic component assembly700at various stags of manufacture.

As shown inFIG. 10, the assembly includes a first magnetic core piece702and the pre-formed winding clip604forming a first subassembly. In the embodiment shown, the first core piece702is a U core having a U shape including a substantially planar surface704and a surface706opposing the planar surface704that includes a first leg708, a second leg710, and a clip channel712defined between the first and second legs708and710. The first magnetic core piece702may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art. In different embodiments, symmetrical and asymmetrical U-cores may be utilized as described above.

As shown inFIG. 11, when the clip604is coupled to the core piece a subassembly720is formed. The main winding section606of the clip604is slidably received in the clip channel712and the remaining sections608,610,612,614of the clip604wrap around the outer perimeter of the leg710of the first core piece700. That is, the leg710of the first core piece702is received in the interior cavity616of the clip604. Each section606,608,610,612,614of the clip604physically abuts or engages a different side surface or face of the leg710of the core piece602. The leg710is securely received and cradled within the clip604such that the subassembly720may be moved as a unit in further assembly steps of magnetic components.

In the exemplary embodiment shown, the clip604is only partially received in the clip channel712such that the clip604projects from the surface706of the core piece702in the subassembly720. Specifically, the winding section606of the clip604is engaged with the clip channel712with the remaining608,610,612,614of the clip604physically abutting or engaging a different side surface or face of the leg710of the core piece702. The terminal lead sections612,614extend substantially parallel to the clip channel712and are exposed on the bottom surface of the core leg710for surface mount connection to a circuit board.

The leg710of the core piece702is securely received and cradled within the clip604such that the subassembly720may be moved as a unit in further assembly steps of magnetic components.

As shown inFIG. 12, the subassembly720is inter-fitted with a second magnetic core piece730. The second core piece730is a U core having a U shape including a substantially planar surface732and a surface734opposing the planar surface732that includes a first leg734, a second leg736, and a clip channel738defined between the first and second legs734and736. The second magnetic core piece730may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art. The second core piece730may likewise be fabricated from the same or different material as the first magnetic core piece702. In different embodiments, symmetrical and asymmetrical U-cores may be utilized as described above.

The second core piece730in the example shown is substantially identically sized and shaped as the core piece702, but is arranged in an opposing, mirror image orientation to the first core piece702. The clip channel738of the second core piece730receives an exposed portion of the clip604such that the clip surrounds an outer perimeter of the leg736of the second core piece730. As such, the main winding section610of the clip604is received partly in the clip channel712of the first core piece702and is received partly in the clip channel738of the second core piece730. The remaining sections608,610,612,614of the clip604partly enclose a portion of the leg710of the first core piece702and partly enclose a portion of the leg736of the second core piece730. When so assembled, the first and second core pieces702,730may be bonded together with adhesives and the like.

As shown inFIG. 13, in the completed component700physical gaps752may be formed between the core pieces702and730and may provide desirable performance characteristics for a power inductor, and potentially for other types of magnetic components in other embodiments. In the embodiment shown, the gaps752extend between the opposing core pieces702and730in a plane perpendicular to the main winding section610(FIG. 10) of the clip604and substantially bisect the main winding portion610(FIG. 10) of the clip604. The size of the gaps752may be varied by adjusting the dimensions of the clip channels712(FIG. 10) and 738(FIG. 12) in the first and second core pieces702and730and/or the lateral dimension of clip604extending between the opposed core pieces702,730. By varying the dimensions of the gaps, the performance characteristics of the resultant magnetic component may be varied to meet particular objectives and provide a variety of power inductors, for example, having different performance characteristics in a uniform package size and with relatively easy and efficient manufacturing step compared to conventional magnetic components.

While a single coil embodiment has been described in relation toFIGS. 10-13, it is recognized that multiple coil embodiments are possible in further and/or alternative embodiments.

FIGS. 14-17illustrate another magnetic component assembly800at various stages of manufacture.

As shown inFIG. 14, the assembly includes a first magnetic core piece802and the pre-formed winding clip604forming a first subassembly. In the embodiment shown, the first core piece802is an L-shaped core including a first elongated leg804and a second truncated leg806extending at approximate a right angle (90°) from the first leg804. The second leg806defines a raised stop face or stop surface808for mistake proof engagement with the clip604as described above. The first magnetic core piece802may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art.

As shown inFIG. 15, when the clip604is coupled to the core piece802a subassembly820is formed. The first leg804of the first core piece802is received in the interior cavity616of the clip604and the clip is slidingly brought into engagement with the stop surface808to ensure correct positioning of the coil604. Each section606,608,610,612,614of the clip604physically abuts or engages a different side surface or face of the leg804of the core piece802. The leg804is securely received and cradled within the clip604such that the subassembly820may be moved as a unit in further assembly steps of magnetic components.

As shown inFIG. 16, the subassembly820is inter-fitted with a second magnetic core piece830overlying the subassembly820. The second core piece830is an L-shaped core including a first elongated leg832and a second truncated leg834extending at approximate a right angle (90°) from the first leg832. The second magnetic core piece830may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art. The second core piece830may likewise be fabricated from the same or different material as the first magnetic core piece802.

The second core piece830in the example shown is substantially identically sized and shaped as the core piece802, but is reversed 180° and arranged in an opposing orientation to the first core piece802. The coil604is effectively captured between the opposed truncated legs806,834of the respective core pieces802and830, and the main winding section610(FIG. 14) of the coil604is sandwiched between the elongated legs804,832of the respective core pieces802and830. When so assembled, the first and second core pieces802,830may be bonded together with adhesives and the like.

As shown inFIG. 17, in the completed component800a physical gap852may be formed between the main winding section606of the clip604and the second core piece830and/or other portions of the opposed core pieces800and830. The gaps852may provide desirable performance characteristics for a power inductor, and potentially for other types of magnetic components in other embodiments. In the embodiment shown, the gap852extends in a plane substantially parallel to the main winding portion610(FIG. 10) of the leg834of the second core piece830. The size of the gaps852may be varied by adjusting the dimensions of the leg834of the second core piece830the and/or the dimension of the clip604. By varying the dimension of the gap, the performance characteristics of the resultant magnetic component may be varied to meet particular objectives and provide a variety of power inductors, for example, having different performance characteristics in a uniform package size and with relatively easy and efficient manufacturing step compared to conventional magnetic components.

While a single coil embodiment has been described in relation toFIGS. 14-17, it is recognized that multiple coil embodiments are possible in further and/or alternative embodiments.

FIGS. 18-21illustrate another magnetic component assembly900at various stages of manufacture.

As shown inFIG. 18, the assembly includes a first magnetic core piece802and the pre-formed winding clip604forming a first subassembly. In the embodiment shown, the first core piece802is an L-shaped core including a first elongated leg804and a second truncated leg806extending at approximate a right angle (90°) from the first leg804. The second leg806defines a raised stop face or stop surface808for mistake proof engagement with the clip604as described above. The first magnetic core piece802may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art.

As shown inFIG. 19, when the clip604is coupled to the core piece802a subassembly920is formed. The first leg804of the first core piece802is completely received in the interior cavity616of the clip604and the clip is brought into sliding engagement with the stop surface808to ensure correct positioning of the coil604. In contrast to the assembly820shown inFIG. 15, no portion of the leg804extends or projects beyond the clip in a direction opposing the stop surface808. Each section606,608,610,612,614of the clip604physically abuts or engages a different side surface or face of the leg804of the core piece802. The leg804is securely received and cradled within the clip604such that the subassembly820may be moved as a unit in further assembly steps of magnetic components.

As shown inFIG. 20, the subassembly920is inter-fitted with a second magnetic core piece930overlying the subassembly920. The second core piece930is an L-shaped core including a first elongated leg932and a second truncated leg934extending at approximate a right angle (90°) from the first leg932. The second magnetic core piece930may be fabricated from any of the magnetic materials described above and associated techniques, or alternatively may be fabricated from other suitable materials and techniques known in the art. The second core piece930may likewise be fabricated from the same or different material as the first magnetic core piece902.

The second core piece930in the example shown is similarly shaped (i.e., L shaped) to the core piece802, but differently dimensioned and proportioned. The lateral sides of the coil604are effectively captured between the opposed truncated legs806,934of the respective core pieces802and930, and the main winding section610(FIG. 18) of the coil604is sandwiched between the elongated legs804,932of the respective core pieces802and930. When so assembled, the first and second core pieces802,930may be bonded together with adhesives and the like.

As shown inFIG. 21, in the completed component900a physical gap952may be formed between the main winding section606of the clip604and the second core piece930and/or other portions of the opposed core pieces802and930. The gap952may provide desirable performance characteristics for a power inductor, and potentially for other types of magnetic components in other embodiments. In the embodiment shown, the gap952extends in a plane substantially parallel to the main winding portion610(FIG. 10) of the leg834of the second core piece830. The size of the gap952may be varied by adjusting the dimensions of the legs806and934of the core pieces802and930the and/or the dimension of the clip604. By varying the dimension of the gap, the performance characteristics of the resultant magnetic component may be varied to meet particular objectives and provide a variety of power inductors, for example, having different performance characteristics in a uniform package size and with relatively easy and efficient manufacturing step compared to conventional magnetic components.

While a single coil embodiment has been described in relation toFIGS. 18-21, it is recognized that multiple coil embodiments are possible in further and/or alternative embodiments.

FIG. 22illustrates another magnetic component assembly1000in various stages of manufacture. As shown inFIG. 21A, a first magnetic body1002is formed, which may be a single piece construction or multiple piece construction in accordance with any of the embodiments described. In the sectional view shown inFIG. 21, a main winding section1004of a pre-formed clip passes through the magnetic body1002in an axial direction.

As shown inFIG. 21B, a second magnetic body1006is formed, which may be a single piece construction or multiple piece construction in accordance with any of the embodiments described. The second magnetic body1006, however, is fabricated from a different magnetic material and hence has different magnetic properties than the first magnetic body1002. In the sectional view shown inFIG. 21, the main winding section1004of the pre-formed clip passes through the magnetic body1002in an axial direction.

As shown inFIG. 21C, the first and second magnetic bodies1002and1006are arranged alongside one another and coupled to one another. The axial length of the coupled bodies1002and1006is the sum of the respective lengths of the bodies1002and1006individually. The main winding section1004extends across the axial length of the bodies1002and1006such that a portion of the main winding section1004is in contact with the magnetic material of the first body1002and another portion of the main winding section1004is in contact with the magnetic material of the second body1002. Different flux paths and performance characteristics are therefore made possible in the different bodies1002and1006, with portions of the same coil section1004receiving the benefit of each of the different magnetic materials utilized. Additionally, one or more physical gaps may be provided in some or all of the magnetic bodies1002and1006to provide still further performance variations and attributes. Varying inductance values and widely varying performance attributes of inductors may be achieved in such a manner by strategically selecting and jointing n number of magnetic bodies, whether physically gapped or not, and assembling with them with one or more coils.

FIGS. 23 and 24illustrate another magnetic component assembly1100in exploded view and assembled view, respectively.

As shown inFIG. 23, the component assembly1100includes the assembly includes the first magnetic core piece702and the pre-formed winding clip604forming a first subassembly720as described above in relation toFIG. 11. The assembly100further includes the second magnetic core piece730, also fitted with a pre-formed winding clip604forming a second subassembly1102. Situated between and separating the first and second subassemblies is a third magnetic core piece1104having a first clip channel1106and a second clip channel1108opposing the first clip channel1106. The third magnetic core piece1104may be formed in the shape of an I-beam as shown inFIG. 23. Alternatively stated, the third magnetic core piece1104may include mutually opposed faces each having a U-shape with the clip channels1106,1108extending between respective legs.

The first clip channel1106faces the first subsassembly720and accepts a portion of the clip604thereof. The second clip channel1108faces the second subassembly1102and accepts a portion of the clip604thereof. When assembled, as shown inFIG. 24, the clips604are spaced apart from one another by the third magnetic core piece1104, and physical gaps752extend between the first and second core pieces702and1104, and the third and second core pieces1104and730. In the exemplary embodiments shown, the gaps752extend between the opposing core pieces702and1104, and the core pieces1104and730in a plane perpendicular to the main winding section610(FIG. 10) of each clip604and substantially bisect the main winding portion610(FIG. 10) of each clip604.

In various embodiments, the magnetic material used to fabricate the third core piece1104may be the same or different from the magnetic materials used to fabricate the first and second piece702and730, and hence the third core piece may have the same or different magnetic properties as the core piece702or730. Thus, the main winding sections610of the clips604may extend across and be in contact with different magnetic materials in such an embodiment. Different flux paths and performance characteristics are therefore made possible in the different bodies702,1104and730, with portions of the clips604receiving the benefit of each of the different magnetic materials utilized.

Additional magnetic pieces1104may be provided and utilized with additional clips604to extend the axial length of the assembly100and provide still further benefits in a relatively compact arrangement.

It is contemplated that the component assemblies600(FIG. 9),800(FIG. 17),900(FIG. 21) could similarly be provided with a third magnetic core piece (or additional core pieces) inter-fitted with additional clips to provide other variations of magnetic component assemblies. Such embodiments may be particularly beneficial for multi-phase power inductor components.

The advantages and benefits of the invention are now believed to be apparent from the exemplary embodiments described. It is further believed that further and alternative embodiments could be derived by those in the art having the benefit of the present disclosure while still being within the scope and spirit of the exemplary claims submitted herewith.

One exemplary embodiment of a magnetic component assembly has been disclosed that comprises: a first magnetic core piece; a first pre-formed clip coupled to said first magnetic core piece; and a second magnetic core piece fitted with the first magnetic core piece and the coupled coil.

Optionally, the first pre-formed clip may include a flat conductor formed substantially in a C-shape. The C-shape includes a first leg and a second leg, with the preformed clip further comprising terminal leads extending from each of the first and second leads. The first pre-formed clip may define a substantially rectangular interior cavity, the interior cavity being extended over the first core piece. The first core piece may be dimensioned to be substantially coextensive with the interior cavity of the first preformed clip.

The second magnetic core piece may optionally define a slot dimensioned to receive and contain the first core piece, and the first and second magnetic core pieces are physically gapped from one another. The second magnetic core piece is substantially U-shaped.

As another option, the first magnetic core piece may include a first leg, a second leg, and a clip channel defined between the first leg and the second leg, and a portion of the first pre-form clip may be received in the clip channel of the first magnetic core piece. The second magnetic core piece may likewise include a first leg, a second leg, and a clip channel defined between the first leg and the second leg, with a portion of the first pre-form clip received in the clip channel of the second magnetic core piece. The pre-formed clip may comprise a flat conductor formed substantially in a C-shape. The C-shape may include a first leg and a second leg, with preformed clip further comprising terminal leads extending from each of the first and second leads, the terminal leads extending substantially parallel to the clip channel in one of the first and second magnetic core pieces. The pre-formed clip may further define a substantially rectangular interior cavity, and the interior cavity may be extended over the first magnetic core piece and wrap around one of the first and second legs.

In another option, the first magnetic core piece may optionally be substantially L-shaped. The L-shaped magnetic core piece may include a long leg and a short leg extending substantially perpendicularly from the long leg. The pre-first formed clip may define a substantially rectangular interior cavity, with the interior cavity being extended over and wrapping around a portion of the long leg. The second magnetic core piece may also be substantially L-shaped, with the second magnetic core piece being reversed relative to the first magnetic core piece and overlying the first pre-formed coil. The first and second L-shaped magnetic cores may be substantially identically sized and shaped or differently sized and shaped.

As another option, the first and second magnetic core pieces are arranged alongside one another and are coupled to one another, with the first pre-formed coil extending across and in intimate contact with each of the plurality of magnetic core pieces. At least two of the plurality of magnetic core pieces may optionally be fabricated from different magnetic materials having different magnetic properties, including but not limited to an amorphous powder material.

A third magnetic core piece may optionally be interposed between the first and second magnetic core piece, and a second preformed clip may be provided and fitted with the second magnetic core piece and the third magnetic core piece.

An exemplary method of forming a magnetic component is also disclosed. The component includes first and second magnetic core pieces and a pre-formed winding clip. The method comprises: coupling the pre-formed winding clip to the first magnetic core piece; and assembling the coupled coil and first magnetic piece to the second magnetic piece, whereby the first and second magnetic piece collectively surround and enclose a portion of the C-shaped clip.

Optionally, the pre-formed winding clip may define an interior cavity, and coupling the pre-formed winding clip to the first magnetic core piece may comprise inserting a portion of the first magnetic core piece into the interior cavity.

Coupling the pre-formed winding clip to the first magnetic core piece may optionally further comprise sliding the pre-formed winding clip along the first magnetic core piece until the pre-formed winding clip abuts a stop surface.

The pre-formed winding clip may optionally be substantially C-shaped, and one of the first and second magnetic core may optionally be U-shaped.

As another option, both of the first and second magnetic core pieces may be U-shaped, with each of the U-shaped core pieces receives a portion of the C-shaped winding clip.

In still another option, the pre-formed winding clip may be substantially C-shaped, and one of the first and second magnetic core pieces may be L-shaped. Further, both of the first and second magnetic core pieces may optionally be L-shaped, and the L-shaped core pieces may be reversed relative to one another.