PLANAR INDUCTOR DEVICES
[0001] The invention relates to electronic devices such as transformers, inductors, filters, couplers, baluns, diplexers, multiplexers, modules or choices.
[0002] Some electronic inductive devices include conductive coils wrapped around a ferrite component. For example, the inductive devices can include one or more inductors, transformers, or chokes. In general, a wire or set of wires is helically wrapped around an iron or magnetic body several times. Current flows through the wire and generates magnetic flux in the magnetic body. The magnetic flux may be used to induce current in another conductive coil and/or filter out components of the current.
[0003] Some of these known inductive devices are not without their shortcomings. For example, traditional inductors, transformers, or chokes can be relatively large and/or limited in topology and performance, especially in the context of Ethernet devices and other communication devices. The ferrites can be relatively large, and the conductive coils that are hand or machine-wrapped around the ferrites can consume relatively large amounts of space. Such inductive devices may need to be mounted on top of circuit boards that are included in the communication device and, as a result, increase the size of the communication device.
[0004] However, when the size of the inductive device is decreased, the relatively brittle ferrites may be damaged and/or break during incorporation of the inductor, transformer, or choke into the communication device. For example, the hand- or machine- wrapping of conductive wire around the relatively small ferrites can be difficult, if not impossible to reliably achieve.
[0005] A need exists for a smaller inductive device that includes a ferrite with conductive coils extending around the ferrite.
[0006] This problem is solved by a planar inductor device according to claim 1.
[0007] According to the invention, a planar inductor device comprises a substrate that vertically extends from an upper surface of the substrate to an opposite lower surface of the substrate, and laterally extends from a first edge to a second edge of the substrate. A ferrite body is disposed within the substrate. Upper conductors are disposed above the ferrite
body, and lower conductors are disposed below the ferrite body. Conductive vias extend through the substrate and are conductively coupled with the upper conductors and with the lower conductors. The vias, the upper conductors, and the lower conductors form one or more conductive coils that encircle the ferrite body in the substrate. At least one of the first edge or the second edge passes through one or more of the vias such that the vias are exposed at the at least one of the first edge or the second edge.
[0008] The invention will now be described by way of example with reference to the accompanying drawings wherein:
[0009] Figure 1 is a side view of one embodiment of a planar inductor device.
[0010] Figure 2 is a top view of an upper surface of the planar inductor device shown in Figure 1.
[001 1] Figure 3 is a top view of a planar inductor device in accordance with another embodiment.
[0012] Figure 4 is a perspective view of a portion of the inductor device shown in Figure 3.
[0013] Figure 5 is a top view of a planar inductor device in accordance with another embodiment.
[0014] Figure 6 is a side view of the planar inductor device shown in Figure 5.
[0015] Figure 7 is a schematic view of a planar inductor device in accordance with another embodiment.
[0016] Figure 8 is a perspective view of a planar inductor device in accordance with another embodiment.
[0017] Figure 9 is a top view of the planar inductor device shown in Figure 8.
[0018] Figure 10 is a perspective view of a planar inductor device in accordance with another embodiment.
[0019] Figure 1 1 is a top view of a ferrite body in accordance with one embodiment.
[0020] Figure 12 is a top view of a multilayer inductor device in accordance with one embodiment.
[0021] Figure 13 is a perspective view of the device shown in Figure 12.
[0022] Figure 14 is an exploded view of the device shown in Figure 12.
[0023] Figure 15 is a cross-sectional view of another embodiment of a planar inductor device.
[0024] Figure 16 is a cross-sectional view of another embodiment of a planar inductor device.
[0025] Figure 17 is a cross-sectional view of another embodiment of the planar inductor device shown in Figure 16.
[0026] Figure 18 is a top view of another embodiment of the planar inductor device shown in Figures 1 and 2.
[0027] Figure 19 is a cross- sectional view of another embodiment of a planar inductor device.
[0028] Figure 20 is a cross-sectional view of another embodiment of a planar inductor device.
[0029] Figures 21 through 23 illustrate different techniques for conductively coupling conductors and/or conductive layers in one or of the embodiments described herein.
[0030] Figure 24 is a side view of a planar inductor device in accordance with another embodiment.
[0031] Figure 25 is an exploded view of one embodiment of a subset of layers in a substrate shown in Figure 24.
[0032] Figure 26 is a schematic view of the inductor device shown in Figure 24 in accordance with one embodiment.
[0033] Figure 1 is a side view of one embodiment of a planar inductor device 100. The device 100 includes a planar substrate 102 with one or more electronic components of the device 100 embedded in the substrate 102. By "planar," it is meant that the substrate 102 is larger along two perpendicular dimensions than in a third perpendicular direction. The substrate 102 may be a flexible and non-rigid sheet, such as a sheet of cured epoxy, or a rigid or semi-rigid board, such as a printed circuit board (PCB) formed of FR-4.
[0034] The substrate 102 has a thickness dimension 104 that is vertically measured from a lower- surface 106 to an opposite upper surface 108. The thickness dimension 104 may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension 104 may be a larger distance.
[0035] In one embodiment, the substrate 102 includes an interior cavity 120. The interior cavity 120 may be at least partially filled with a flexible material, such as cured epoxy, or with air. A ferrite body 1 10 is entirely disposed within the substrate 102 in one embodiment. For example, the ferrite body 1 10 may be located in the interior cavity 120 surrounded by the flexible material or air. The ferrite body 1 10 can be entirely disposed within the thickness dimension 104 of the substrate 102 and not protrude or project through a plane defined by the upper surface 108 of the substrate 102 and/or a plane defined by the lower surface 106. The ferrite body 1 10 may be positioned within a cavity of a substrate with the cavity being filled with air or a flexible material (such as epoxy) in accordance with one or more embodiments described in U.S. Patent Application Serial No. 12/699,777, which is entitled "Packaged Structure Having Magnetic Component And Method Thereof (referred to herein as " '777 Application") and or U.S. Patent Application No. 12/592,771, which is entitled "Manufacture And Use Of Planar Embedded Magnetics As Discrete Components And In Integrated Connectors" (referred to herein as the " '771 Application"). The entire disclosures of the '777 and the '771 Applications are incorporated by reference herein.
[0036] The ferrite body 1 10 is shown as having an approximately rectangular shape. Alternatively, the ferrite body 1 10 may have another shape, such as a cylinder, toroid, annulus, E-shape, and the like. The ferrite body 1 10 may include or be formed from iron, an iron alloy, or a magnetic material. The ferrite body 1 10 can be enveloped in a flexible elastic epoxy or in air cavity within the cavity 120 of the substrate 102. When the ferrite body 1 10 is
enveloped in epoxy, the epoxy can be premixed with high permeability materials aid or increase the inductance per unit length of the ferrite body 1 10. Examples of such high permeability materials include cobalt, nickel, manganese, chromium, iron, and the like. Alternatively, the cavity 120 of the substrate 102 can be filled or substantially filled with an epoxy having high permeability materials without the ferrite body 1 10 being disposed within the substrate 102. For example, the ferrite body 1 10 may be replaced with a body formed from an epoxy having high permeability materials in the epoxy.
[0037] The device 100 includes a plurality of interconnected upper conductors 1 14, conductive vias 1 16, and lower conductors 1 18. The upper conductors 1 14 may include conductive traces that are deposited on the upper surface 108 of the substrate 102 and/or below the upper surface 108. For example, the substrate 102 may include a plurality of sublayers stacked on top of each other, such as on one or more layers of FR-4 stacked on top of each other. The upper conductors 1 14 can be deposited on or in one of the sub-layers disposed below the upper surface 108. The lower conductors 1 18 may include conductive traces that are deposited on the lower surface 106 of the substrate 102 and/or above the lower surface 106. For example, the lower conductor's .1 18 may be deposited on or in one of the sub-layers disposed above the lower surface 106.
[0038] The vias 1 16 may be formed as holes or channels that vertically extend through all or a portion of the thickness dimension 104 of the substrate 102. In one embodiment, the vias 116 are formed using lasers and/or mechanical drilling of the substrate 102. For example, the vias 1 16 may be formed into the substrate 102 using C02 lasers, ultraviolet (UV) lasers, and/or or mutli-head mechanical drilling machines with via diameter sizes in the range of 25 micrometers to 500 micrometers. Alternatively, different techniques may be used to form the vias 1 16 and/or different sized vias 1 16 may be used.
[0039] In the illustrated embodiment, the vias 116 are disposed outside of the cavity 120 of the substrate 102. For example, the vias 1 16 shown in Figure 2 do not extend through the cavity 120. Alternatively, the vias 1 16 may at least partially extend through the cavity 120. For example, at least a portion of the vias 1 16 located inside the substrate 102 may extend through the cavity 120 and/or the flexible material or air inside the cavity 120.
[0040] The vias 1 16 may extend through the entirety of the thickness dimension 104 along center axes 122 from the upper surface 108 to the lower surface 106, The vias 1 16
may be filed with a conductive material, such as a conductive solder, and/or may be conductively plated. For example, the exposed surfaces of the substrate 102 inside the vias 1 16 may be plated with a conductive material, such as a metal or metal alloy. The vias 1 16 conductively couple the upper conductors 1 14 with the lower conductors 1 18.
[0041] In one embodiment, one or more of the upper conductors 1 14 and/or the lower conductors 1 18 may be formed from a combination of conductive traces and wire bonds. For example, the vias 1 16 may extend through the substrate 102 and be conductively coupled with the conductive traces and wire bonds of the upper conductors 1 14 and with the lower conductors 1 18.
[0042] Figure 2 is a top view of the upper surface 108 of the planar inductor device 100. The upper conductors 1 14, the lower conductors 1 18, and the vias 1 16 are arranged around the ferrite body 1 10 to form a conductive coil 200. For example, the vias 1 16 are arranged in a plurality of pairs 202, with each pair 202 including vias 1 16 on opposite sides 204, 206 of the ferrite body 1 10. The vias 1 16 in each pair 202 are conductively coupled along the upper surface 108 of the substrate 102 by one of the upper conductors 1 14 in the illustrated embodiment. Alternatively, the vias 1 16 may be coupled by more than one of the upper conductors 1 14. As shown in Figure 2, the upper conductors 1 14 are elongated conductive bodies that extend from a first via 1 16 in each pair 202 to a second, opposite via 116 in the same pair 202.
[0043] The vias 1 16 vertically extend through the substrate 102 on opposite sides of the ferrite body 1 10 from the upper conductors 1 14 to the lower conductors 1 18. In the illustrated embodiment, the vias 1 16 have circular shapes, but alternatively may have another shape, such as a polygon shape. The vias 1 16 define channels or holes that vertically extend through the substrate 102. As shown in Figure 2, the vias 1 16 are encircled by the substrate 102. For example, the substrate 102 extends around and encircles the entire outer periphery of the vias 1 16 throughout the thickness dimension 104 of the substrate 102. The channels or holes of the viasl l6 are only open at the upper surface 108 and at the lower surface 106 of the vias 1 16 but are surrounded by the substrate 102 from the lower surface 106 to the upper surface 108 in the illustrated embodiment.
[0044] While the illustrated embodiment is a single coil device, multiple conductive pathways can be helically wrapped around the ferrite body to form chokes and
transformers having two or more conductive coils. For Power over Ethernet (POE) or other applications, a longer bar shape-inductor device that can accommodate two or more conductive coils may be used. Each pair of conductive coils can support an opposite polarity of a voltage required for the POE application. If the two or more conductive coils are wound in the same direction around the ferrite body, the ferrite body may not saturate for the POE application.
[0045] As shown in Figure 2, each lower conductor 1 18 conductively couples vias 1 16 in different pairs 202 of the vias 1 16. For example, each lower conductor 1 18 conductively couples a first via 116 in a first pair 202 of the vias 1 16 on the first side 204 of the ferrite body 1 10 with a second via 1 16 in a second, different pair 202 of the vias 1 16 on the opposite second side 206 of the ferrite body 1 10. The lower conductors 1 18 are elongated conductive bodies in the illustrated embodiment. The lower conductors 1 18 and the upper conductors 1 14 are obliquely oriented relative to each other. For example, as shown in Figure 2, the lower conductors 1 18 are elongated along directions disposed at acute angles relative to the directions along which the upper conductors 1 14 are elongated.
[0046] The conductively coupled upper conductors 1 14, the vias 1 16, and the lower conductors 1 18 form the conductive coil 200 that helically wraps or encircles the ferrite body 1 10. By "encircle," the conductive coil 200 may follow a helical path that moves around the outer perimeter of the ferrite body 1 10. An encircling path of the conductive coil 200 can extend around an entire 360 degrees of the ferrite body 1 10, even though the upper conductors 1 14, the vias 1 16, and the lower conductors 1 18 do not follow a pathway that is a perfect circle.
[0047] The coil 200 can extend from a first via 1 16 disposed along the first side 204 of the ferrite body 1 10 to a second via 1 16 in the same pair 202 of the vias 1 16 on the opposite, second side 206 of the ferrite body 1 10. The second via 1 16 extends along the second side 206 of the ferrite body 1 10 through the thickness dimension 104 of the substrate 102 to a first lower conductor 1 18. The first lower conductor 1 18 conductively couples the second via 1 16 with a third via 1 16 in a second, different pair 202 of the vias 1 16 on the first side 204 of the ferrite body 1 10. The third via 1 16 extends along the first side 204 of the ferrite body 1 10 to a first upper conductor 1 14. The first upper conductor 1 14 conductively couples the third via 1 16 with a fourth via 1 16 in the same set 202 of the vias 1 16. The
remaining vias 1 16, upper conductors 1 14, and lower conductors 1 18 continue to form the conductive coil 200 that wraps around the ferrite body 1 10.
[0048] In the illustrated embodiment, the ferrite body 1 10 is elongated between opposite first and second ends 208, 210. The coil 200 helically wraps around the ferrite body 1 10 from at or near the first end 208 toward the opposite end 210. The coil 200 has a lateral length dimension 220 that is measured along the length of the coil 200 and in a direction that is perpendicular to the thickness dimension 104. The length dimension 220 may be measured from center lines of the vias 1 16 on opposite ends of the coil 200.
[0049] The device 100 may be included into or connected to an electric circuit 212 to provide an inductive element, or inductor, to the circuit. For example, two or more of the vias 1 16, the upper conductors 1 14, and/or the lower conductors 1 18 may be conductively coupled to conductors 214, 216 (e.g., wires, buses, terminals, contacts, or other conductive bodies) of the circuit. One conductor 214 of the circuit 212 can be coupled with a first via 1 16, upper conductor 1 14, or lower conductor 1 18 while the other conductor 216 of the circuit 212 is coupled with a second, different via 1 16, upper conductor 1 14, or lower conductor 1 18. In one embodiment, the circuit 212 is connected to two different vias 1 16 in different pairs 202 of the vias 1 16.
[0050] The device 100 may provide an inductive element to the circuit 212 that has an operator-customizable inductance characteristic. In operation, current from the circuit 212 flows through the coil 200 of the device 100. At least some of the energy of the current is stored as magnetic energy in the ferrite body 1 10. The coil 200 may be used to delay and/or reshape currents flowing through the circuit 212, such as by filtering relatively high frequencies from the current. The amount of magnetic energy stored in the ferrite body 1 10 can represent an inductance characteristic of the device 100. The inductance characteristic provided by the device 100 may be altered by changing a lateral distance dimension 218 between the contacts between the conductors 214, 216 and the coil 200. For example, the inductance of the device 100 may increase when the circuit 212 is connected to vias 1 16 (or upper conductors 1 14 and/or lower conductors 1 18) that are farther apart from each other. Conversely, the inductance of the device 100 may decrease when the circuit 212 is connected to vias 1 16, upper conductors 1 14, and/or lower conductors 1 18 that are disposed closer to each other.
[0051] Figure 18 is a top view of another embodiment of the planar inductor device 100 shown in Figures 1 and 2 where 2 coils are wrapped around the ferrite body. The device 100 is shown without the substrate 102 in order to more clearly illustrate the upper conductors 1 14, lower conductors 1 18, and vias 1 16. The ferrite body 1 10 is shown in phantom so that the lower conductors 1 18 are visible. In the illustrated embodiment, the vias 1 16 are staggered so that the upper conductors 1 14 are closer to each other and the lower conductors 1 18 are closer to each other. For example, in the embodiment shown in Figure 2, the vias 1 16 are linearly aligned with each other at the upper surface 108 and at the lower surface 106 of the substrate 102.
[0052] In contrast, the vias 1 16 in the embodiment shown in Figure 18 are staggered on each side of the ferrite body 1 10 such that different groups 2100, 2102 of the vias 116 are linearly aligned along different lines 2104, 2106. The staggering of the vias 1 16 can cause the upper conductors 1 18 to be closer to each other and/or the lower conductors 1 14 to be closer to each other, as shown in Figure 18. The inductance or impedance per unit length of the device 100 may be increased by locating the upper conductors 1 18 closer to each other and/or the lower conductors 1 14 closer to each other.
[0053] Figure 3 is a top view of a planar inductor device 300 in accordance with another embodiment. The device 300 may be similar to the device 100 shown in Figure 1. For example, the device 300 includes a substrate 302 having a thickness dimension 400 (shown in Figure 4) that vertically extends from a lower surface 402 (shown in Figure 4) to an opposite upper surface 404 (shown in Figure 4). The thickness dimension 400 may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension 400 may be a larger distance. The device 300 also includes a ferrite body 310 that may be entirely disposed within the thickness dimension 400 of the substrate 302. In one embodiment, the substrate 302 may include an interior cavity, such as the cavity 120 (shown in Figure 1) of the substrate 102 (shown in Figure 1), with the ferrite body 310 disposed in the cavity. Upper conductors 314 and lower conductors 318 are provided at or on upper and lower surfaces 404, 402 (shown in Figure 4) of the substrate 302, respectively, and conductive vias 316 extend through the thickness dimension 400 of the substrate 302 and conductively couple the upper conductors 314 with the lower conductors 318. Similar to the device 100, the upper
conductors 314, the lower conductors 318, and the vias 316 form a conductive coil 320 that helically wraps around the ferrite body 310.
[0054] One difference between the device 100 shown in Figure 1 and the device 300 shown in Figure 3 is that the vias 316 are not encircled or enclosed by the substrate 302 throughout the thickness dimension 400 (shown in Figure 4) of the substrate 302. For example, the substrate 302 laterally extends between opposite edges 322, 324 along a lateral direction 326. The lateral direction 326 can be perpendicular to the vertical direction in which the thickness dimension 400 is measured and/or perpendicular to a center axis 328 of the coil 320 and that the coil 320 helically wraps around. As shown in Figure 3, the edges 322, 324 extend through the vias 316 such that the vias 316 are at least partially exposed along the edges 322, 324.
[0055] With continued reference to Figure 3, Figure 4 is a perspective view of a portion of the inductor device 300. As described above, the substrate 302 of the device 300 has the thickness dimension 400 that vertically extends from the lower surface 402 to the upper surface 404. The vias 316 shown in Figures 3 and 4 are plated vias. For example, the vias 316 are formed as holes or channels that extend through the thickness dimension 400 and have interior surfaces that are coated or plated with a conductive material, such as a metal or metal alloy. Alternatively, the vias 316 may be filled with a conductive material, such as a metal, metal alloy, or solder.
[0056] The edges 322, 324 of the substrate 302 "cut," or extend through, the vias 316 such that conductive interior surfaces 330 of the vias 316 are exposed. In contrast to the vias 1 16 (shown in Figure 1) of the device 100 (shown in Figure 1) that are encircled by the substrate 102 (shown in Figure 1) throughout the thickness dimension 104 (shown in Figure 1) of the substrate 102, the vias 316 are exposed and not entirely encircled by the substrate 302 throughout the thickness dimension 400 of the substrate 302. The exposed interior surfaces 330 of the vias 316 provide conductive castellations 406 of the device 300. The castellations 406 represent conductive surfaces of the device 300 that are conductively coupled with the coil 320 formed in the substrate 302 along one or more of the edges 322, 324 of the substrate 302. In one embodiment, the castellations 406 are provided by mechanically cutting and removing portions of the vias 316 and the substrate 302 along the edges 322, 324 to expose the edges 322, 324 and the vias 316. Alternatively, the vias 316
may be formed along the outer edges 322, 324 of the substrate 302 without mechanically cutting portions of the substrate 302. For example, semi-circle channels may be formed into the edges 322, 324 of the substrate 302 and then plated with a conductive material to form the vias 316 shown in Figures 3 and 4.
[0057] Similar to the vias 1 16 shown in Figures 1 and 2, the castellations 406 conductively couple the lower conductors 318 (shown in Figure 3) with the upper conductors 314 to form the coil 320 (shown in Figure 3) that helically wraps around the ferrite body 310 (shown in Figure 3). The device 300 may be included into or connected to an electric circuit that is similar to the electric circuit 212 (shown in Figure 2) to provide an inductive element, or inductor, to the circuit. Such an electric circuit may be conductively coupled to two or more of the castellations 406 of the device 300. The castellations 406 may provide locations that are more easily coupled with the electric circuit. For example, the upper and/or lower surfaces 404, 402 may not be readily accessible and/or may be relatively difficult to access. The edges 322 and/or 324 may be exposed and/or more easily accessible for conductors (e.g., wires, busses, and the like) of the electric circuit to be conductively coupled with the castellations 406. Moreover, the castellations 406 can provide increased conductive areas with which the electric circuit may couple. For example, instead of coupling the electric circuit 212 with the portions of the vias 1 16 that are at or near the upper and/or lower surfaces 108, 106 of the substrate 102, the electric circuit 212 may couple with a much larger conductive area of the castellations 406 along the edges 322, 324 of the device 300. The larger conductive area of the castellations 406 can provide decreased electrical resistance between the coil 320 and the electric circuit.
[0058] Similar to the device 100 (shown in Figure 1), the device 300 may provide an inductive element to the circuit 212 (shown in Figure 2) that has an operator-customizable inductance characteristic. Similar to the inductance characteristic provided by the device 100, the inductance characteristic of the device 300 may be customized based on which castellations 406 are used to couple the coil 320 with the circuit 212. The inductance of the device 300 may increase when the circuit 212 is connected to castellations 406 located farther from each other or decrease when the circuit 212 is connected to castellations 406 located closer to each other. The ability to use different castellations 406 can provide for increased tenability of high precision inductors that may be used or required for filters, diplexers, multiplexers, or baluns. During a back end test, and as ferrites may vary by +/- 20% in ferrite
permeability, the castellations 406 can allow for binning depending on the value of the nominal inductance of the device 300. For example, if the device 300 having a predetermined number of turns of the coil 320 around the ferrite body 310, but the inductance of the device 300 is lower than expected due to variation in the permeability of the ferrite body 310 (e.g., a lower than expected permeability), then a user of the device 300 can use different castellations 406 to electrically couple a circuit with the device 300. The user may select other castellations 406 that can provide increased inductance of the device 300. For example, the user may use castellations 406 that are disposed farther apart. In one embodiment, the user can connect to the castellation 406 or castellations 406 that increase the inductance of the device 300 based on the number of additional turns of the coil 320 that are disposed between the selected castellations 406. As one example, the inductance of the device 300 may be proportional to n2, where "n" represent the number of turns, or times that the coil 320 helically wraps around the ferrite body 300. If the user selects castellations 406 that are located such that there are 10 turns of the coil 320 between the castellations 406 and then changes one of the castellations 406 such that 9 turns of the coil 320 are between the selected castellations 406, then the inductance of the device 300 may be reduced by 20%.
[0059] Figure 5 is a top view of a planar inductor device 500 in accordance with another embodiment. Figure 6 is a side view of the device 500. The device 500 may be similar to the device 100 shown in Figure 1. For example, the device 500 includes a substrate 502 having a thickness dimension 504 that vertically extends from a lower surface 506 to an opposite upper surface 508. The thickness dimension 504 may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension 504 may be a larger distance. The device 500 also includes a ferrite body 510 that may be entirely disposed within the thickness dimension 504 of the substrate 502. In one embodiment, the substrate 502 may include an interior cavity, such as the cavity 120 (shown in Figure 1) of the substrate 102 (shown in Figure 1), with the ferrite body 510 disposed in the cavity. Conductive vias 516 extend through the thickness dimension 504 of the substrate 502.
[0060] The device 500 includes upper conductors 514 that conductively couple the vias 516 along or across the upper surface 508 of the substrate 502 and lower conductors 518 that conductively couple the vias 516 along or across the lower surface 506 of the substrate 502. Similar to the device 100, the upper conductors 514, the lower conductors
518, and the vias 516 form a conductive coil 520 that helically wraps around the ferrite body 310.
[0061] One difference between the device 100 shown in Figure 1 and the device 500 shown in Figures 5 and 6 is that the upper and lower conductors 514, 518 are wires, such as wire bonds, instead of conductive layers or traces that are deposited onto the substrate 502. For example, the upper conductors 514 and/or the lower conductors 518 may be elongated strands, wires, filars, and the like, that are coupled to the vias 516. In one embodiment, the upper and/or lower conductors 514 and/or 518 may be wires that are soldered across the ferrite body 510. The upper and lower conductors 514, 518 are coupled to the vias 516 to provide the coil 520 that helically wraps around the ferrite body 510. The upper and lower conductors 514, 518 are separated from the upper and lower surfaces 508, 506 of the substrate 502 such that the upper and lower conductors 514, 518 do not contact the substrate 502. The upper and lower conductors 514, 518 may be used in place of or in addition to the upper and lower conductors 1 14, 1 18 (shown in Figure 1) to reduce an electric resistance characteristic of the coil 520 and/or to allow for a wirebonding method to be used to provide the upper and/or lower conductors 514, 518. In one embodiment, the upper and/or lower surfaces 508, 506 of the substrate 502 can be protected with a dielectric overmold layer or similar type of material that covers the wire bonds and conductors and protects the device 500.
[0062] Figure 7 is a schematic view of a planar inductor device 1000 in accordance with another embodiment. The device 1000 includes a conductive pathway 1002 and a ferrite body 1016. In the illustrated embodiment, the ferrite body 1016 has a toroid or anulus shape such that the ferrite body 1016 extends around and encircles an opening 1014. Alternatively, the ferrite body 1016 may have another shape, such as a polygon having an opening.
[0063] The conductive pathway 1002 is shown as including a plurality of interconnected sections, including an input section 1004, a current-splitting section 1006, a coil section 1008, a current-combining section 1010, and an output section 1012. The sections 1004, 1006, 1008, 1010, 1012 may be conductively coupled with each other to form the conductive pathway 1002 through which electric current may flow from the input section 1004 to the output section 1012. In the illustrated embodiment, the input section 1004
extends to the current- splitting section 1006. The current-splitting section 1006 extends from the input section 1004 to the coil section 1008. The coil section 1008 extends from the current-splitting section 1006 to the current-combining section 1010. The current-combining section 1010 extends from the coil section 1008 to the output section 1012. The input section 1004 and the output section 1012 may be conductively coupled with an electronic circuit (e.g., the circuit 212 shown in Figure 2) in order to provide an inductive element, such as an inductor, to the circuit. The input section 1004 may receive current from the circuit and the output section 1012 may convey the current to the circuit (or to another circuit or component).
[0064] The input section 1004 of the conductive pathway 1002 is oriented toward the opening 1014 of the ferrite body 1016. In the illustrated embodiment, the input section 1004 is disposed above the ferrite body 1016, or is disposed closer to the viewer of Figure 7 than the ferrite body 1016. The conductive pathway 1002 splits into a plurality of conductive coils 1018 in the current-splitting section 1006, as shown in Figure 7. While the conductive pathway 1002 is split into two coils 1018 in the illustrated embodiment, alternatively, the conductive pathway 1002 may be split into three or more coils 1018. The coils 1018 in the current-splitting section 1006 extend below the ferrite body 1016 and encircle or helically wrap around the ferrite body 1016 in the coil sections 1008.
[0065] Each of the coils 1018 may have similar or equivalent dimensions and/or be formed from the same material as the conductive pathway 1002 in the input section 1004. For example, each coil 1018 may be formed from the same material and/or have the same cross-sectional diameter as the conductive pathway 1002 in the input section 1004. Each of the coils 1018 includes a single turn 1020 around the ferrite body 1016 in the illustrated embodiment. Alternatively, one or more of the coils 1018 may wrap around the ferrite body 1016 multiple times to form multiple turns 1020 around the ferrite body 1016. The coils 1018 form parallel inductive elements of the device 1000. For example, each coil 1018 provides an inductor comprising a conductive pathway 1002 that wraps around the ferrite body 1016.
[0066] The conductive pathways 1002 in the coil sections 1008 combine with each other in the current-combining section 1010. The conductive pathways 1002 combine into a combined conductive pathway 1002 in the current-combining section 1010, with the
combined conductive pathway 1002 extending below the ferrite body 1016 to the output section 1012. Alternatively, the conductive pathways 1002 in the coil section 1008 may combine into the combined conductive pathway 1002 that extends above the ferrite body 1016. The conductive pathway 1002 in the output section 1012 is oriented away from the ferrite body 1016.
[0067] In operation, the device 1000 may be used to provide an inductive element to an electric circuit. The device 1000 may have a lower electric resistance characteristic and/or a larger inductance characteristic relative to inductive elements having a single conductive pathway that wraps around a ferrite body. For example, the conductive pathway 1002 in the input section 1004 may convey an electric current (I) into the device 1000. The current (I) is divided between and conveyed along the multiple conductive pathways 1002 formed in the current-dividing section 1006. The current (I) can be divided among the multiple conductive pathways 1002 in the current-dividing section 1006 into current fractions. In the illustrated embodiment, the current (I) is divided into a first current fraction (Ii) and a second current fraction (I2). The first and second current fractions (It, I2) may be equal or approximately equal. Alternatively, the first and second current fractions (I1} I2) may differ from each other. The conductive pathway 1002 can be divided into more conductive pathways 1002 in the current- splitting section 1006 to further divide the current (I) into more current fractions.
[0068] The current fractions (I1} I2) are separately conveyed around the ferrite body 1016 by the coils 1018 of the conductive pathways 1002. Each of the current fractions (Ii, I2) is smaller than the total current (I). For example, the current fractions (I1 } I2) may be related to the total current (I) as follows:
I = l!+I2 (Equation #1) where I represents the total current flowing through the device 1000, Ii represents the first current fraction, and Ii represents the second current fraction. A resistance characteristic (Ω) of the conductive pathway 1002 and/or one or more of the coils 1018 may be based on the current flowing through the conductive pathway 1002 or coils 1018 according to the following relationship:
(Equation #2) where R represents an electric resistance characteristic of the conductive pathway 1002 or coil 1018, such as resistance or impedance, V represents a voltage or energy characteristic of the current flowing through the conductive pathway 1002 or coil 1018, and I represents the current (e.g., the total current (I), the first current fraction (Ii), or the second current fraction (I2)) flowing through the corresponding conductive pathway 1002 or coil 1018).
[0069] When the total current (I) flowing through the conductive pathway 1002 is divided up into the current fractions (Ii, I2) that separately flow through the parallel coils 1018, the resistance characteristic (R) of each of the coils 1018 can decrease relative to the conductive pathway 1002. For example, the resistance for the current (I) flowing through the conductive pathway 1002 may be halved, or reduced by up to 50%, for the first and/or second current (Ii, I2) flowing through the parallel first and second coils 1018. Reducing the resistance characteristic (R) in the coils 1018 can reduce power losses in the current (I) as the current (I) flows through the device 1000. As described below, the resistance characteristic (R) can be decreased in the device 1000 without an accompanying loss in an inductance characteristic (L) of the device 1000.
[0070] Arrows 1022 indicate the direction in which the current (I) and current fractions (Ij, I2) flow through the device 1000. As the current fractions (I1; I2) flow around the ferrite body 1016, the current fractions (Ii, I2) generate first and second magnetic fluxes (ΦΒΙ, ΦΒ2) in the ferrite body 1016. The magnetic fluxes (ΦΒΙ, Β2) may be based on a number of factors, such as the number of turns 1020 (N) of the coils 1018 around the ferrite body 1016, the magnetic permeability (μ0) of the ferrite body 1016, the cross-sectional area (A) of the conductive pathways 1002 within the coils 1018, the radius (R) of the turn 1020 formed by the coil 1018, and the current fractions (Il s I2) flowing through the coils 1018. In one embodiment, the magnetic fluxes (ΦΒ Ι , ΦΒ2) may be based on the following relationships:
(Equation #3)
Φΐ ~ N (Equation #4)
2nR
where represents the first magnetic flux, represents the second magnetic flux, N represents the number of turns 1020 around the ferrite body 1016, A represents the cross- sectional area of the conductive pathway 1002 in the coil 1018, R represents the radius of curvature of the coil 1018, μ0 represents the magnetic permeability of the ferrite body 1016, Ii represents the first current fraction, and I2 represents the second current fraction. The above equations may represent approximations of the magnetic fluxes (ΦΒΙ , ΦΒ2) and not actual relationships used to determine an exact value of the magnetic fluxes (ΦΒΙ , Β2)· For example, Equations #1 and 2 may indicate which terms in the Equations are proportional, inversely proportional, and the like, with the magnetic fluxes (ΦΒ Ι , ΦΒ2)·
[0071] The directions in which the magnetic fluxes (ΦΒΙ, ΦΒ2) flow in the ferrite body 1016 are based on the direction of flow of the current fractions (Ii, I2) through the coils 1018 of the conductive pathways 1002. For example, as shown in Figure 7, the first magnetic flux (ΦΒΙ) generated by the first current fraction (10 is oriented in the direction of arrow 1024 while the second magnetic flux (ΦΒ2) generated by the second current fraction (I2) is oriented in the direction of the arrow 1026. Due to the direction of current flow and the directions in which the coils 1018 wrap around the ferrite body 1016, the magnetic fluxes (ΦΒΙ, ΦΒ2) are additive. For example, the magnetic fluxes (ΦΒΙ, Β2) may add together and increase a total magnetic flux (ΦΒ) of the device 1000, rather than decrease the total magnetic flux (ΦΒ) of the device 1000. The total magnetic flux (ΦΒ) of the device 1000 may be represented by the following relationship: Β = 1 Β + Φ2 Β (Equation #5) where ΦΒ represents the total magnetic flux, Φ^ represents the first magnetic flux, and Φ^ represents the second magnetic flux.
[0072] The device 1000 can provide an inductor having an inductance characteristic (L). The inductance characteristic (L) represents the magnetic energy generated by the device 1000 when the current (I) flows through the device 1000. In one embodiment, the inductance characteristic (L) of the device 1000 is represented by the following relationship:
Φ
L = B (Equation #5)
where L represents the inductance characteristic of the device 1000, I represents the current flowing through the conductive pathways 1002 of the device 1000, and ΦΒ represents the total magnetic flux generated in the ferrite body 1016 of the device 1000 caused by the flow of current (I) through the device 1000.
[0073] As described above, a resistance characteristic (R) of the device 1000 can be reduced by providing a plurality of the parallel coils 1018 and dividing the current (I) into divided currents (Ij, I2) that separately flow through the parallel coils 1018. The resistance characteristic (R) can represent the total electric impedance or resistance of the conductive pathway 1002 and coils 1018 in the device 1000. The resistance characteristic (R) can be reduced relative to other inductors or inductive elements having the same or approximately the same inductance characteristic (L) as the device 1000. For example, the device 1000 may have approximately the same inductance, but a lower resistance, as another device having a single conductive pathway 1002 that does not include parallel coils 1018 but helically wraps around the ferrite body 1016 for a single turn 1020. The parallel coils 1018 enable the device 1000 to provide the same or approximately the same inductance characteristic (L) without an increase or significant increase in the resistance characteristic (R) of the device 1000.
[0074] Figure 8 is a perspective view of a planar inductor device 1 100 in accordance with another embodiment. Figure 9 is a top view of the device 1 100. The device 1 100 may be similar to the device 1000 that is schematically shown in Figure 7. For example, the device 1 100 may include a conductive pathway that extends toward a ferrite body, includes or is divided into parallel coils that helically wrap around the ferrite body, and recombines the parallel coils into the conductive pathway that extends out of the ferrite body.
[0075] In the illustrated embodiment, the device 1 100 is embedded within a planar substrate 1 102 (shown in Figure 8). The substrate 1 102 may be a flexible and non- rigid sheet, such as a sheet of cured epoxy, or a rigid or semi-rigid board, such as a printed circuit board (PCB) formed of FR-4. The substrate 1 102 is shown in phantom view in Figure 8 and is not shown in Figure 9. The substrate 1 102 vertically extends from a lower surface 1 104 (shown in Figure 8) to an opposite upper surface 1 106 (shown in Figure 8). The substrate 1 102 has a thickness dimension 1 108 (shown in Figure 8) that is measured from the lower surface 1 104 to the upper surface 1 106 along a vertical direction 1 120 (shown in Figure 8) that is oriented perpendicular to the upper surface 1 106. The thickness dimension
1108 may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension 1108 may be a larger distance.
[0076] The device 1100 includes an input conductor 1110 that receives electric current into the device 1100. In the illustrated embodiment, the input conductor 1110 is formed as a planar conductive body. The input conductor 1110 may be deposited as a planar conductive trace on one or more sub-layers of the substrate 1102 (shown in Figure 8) that are disposed between the upper surface 1106 (shown in Figure 8) and the lower surface 1104 (shown in Figure 8). A conductive bus 1112 and/or a conductive bus 1114 (shown in Figure 8) may be coupled with the input conductor 1110 and exposed at or along the upper surface 1106 and the lower surface 1104, respectively, of the substrate 1102. Conductive vias 1122 can couple the buses 1112, 1114 with each other. Multiple vias 1122 can be added to reduce electrical resistance for the device 1100. In some instances, the vias 1122 can be filled with thermally conductive paste or electrically conductive paste to reduce electrical resistance and/or increase thermal conductivity of the device 1100. Alternatively, the input conductor 1110 may be located on the upper surface 1106 or lower surface 1104 of the substrate 1102. The conductive bus 1112 and/or 1114 may receive electric current from an electric circuit, such as from a wire or other conductive body that is coupled with the circuit, and convey the current to the input conductor 1110.
[0077] A ferrite body 1116 is disposed within the substrate 1102 in the illustrated embodiment. The ferrite body 1116 is shown in phantom in Figure 8. The ferrite body 1116 can be entirely located within the substrate 1102 such that no part of the ferrite body 1116 extends above or projects through a plane defined by the upper surface 1106 (shown in Figure 8) of the substrate 1102 and/or a plane defined by the lower surface 1104 of the substrate 1102 (shown in Figure 8). The ferrite body 1116 can have a toroid or anulus shape similar to the shape of the ferrite body 1016 shown in Figure 7. Alternatively, the ferrite body 1116 can have a different shape. The ferrite body 1116 includes an opening 1118 that is similar to the opening 1014 of the ferrite body 1016 shown in Figure 7.
[0078] As shown in Figure 9, the input conductor 1110 extends above the ferrite body 1116 and at least a portion of the opening 1118 in the ferrite body 1116. For example, at least part of the input conductor 1110 may be located between the ferrite body 1116 and
the upper surface 1 106 (shown in Figure 8) of the substrate 1 102 (shown in Figure 8) along or parallel to the vertical direction 1 120 (shown in Figure 8) and at least part of the input conductor 1 1 10 may be between the opening 1 1 18 and the upper surface 1 106 of the substrate 1 102 along the vertical direction 1 120. Alternatively, at least part of the input conductor 1 1 10 may be located between the ferrite body 11 16 and the lower surface 1 104 (shown in Figure 8) of the substrate 1 102 along or parallel to the vertical direction 1 120 and at least part of the input conductor 1 1 10 may be between the opening 1 1 18 and the lower surface 1 104 of the substrate IT 02 along the vertical direction 1 120.
[0079] One or more conductive input vias 1 124 are coupled with the input conductor 1 1 10. The input vias 1 124 include holes or channels that extend through the substrate 1 102 (shown in Figure 8) that are plated or substantially filled with a conductive material (e.g., a metal, metal alloy, or conductive solder). As shown in Figure 9, the input vias 1124 are disposed within the opening 1 1 18 of the ferrite body 1 1 16. In the illustrated embodiment, the device 1 100 includes seven input vias 1 124. Alternatively, a smaller or larger number of input vias 1124 may be provided. The input vias 1 124 can vertically extend through the substrate 1 102 from the input conductor 1 1 10 toward the lower surface 1 104 (shown in Figure 8) of the substrate 1 102. In the illustrated embodiment, the input conductor 1110 and the input vias 1 124 can provide a portion of the conductive pathway 1002 that is represented by the input section 1004 in Figure 7. For example, the input conductor 1 1 10 and the input vias 1 124 may provide a conductive pathway that extends toward and into the opening 1 1 18 of the ferrite body 1 1 16. The input conductor 1 1 10 and the input vias 1 124 may convey the electric current (I) described above in connection with Figure 7 into the device 1 100.
<. [0080] The device 1 100 includes a current-splitting conductor 1 126 that is conductively coupled with the input vias 1 124. The input vias 1 124 conductively couple the input conductor 1 1 10 with the current-splitting conductor 1 126. In the illustrated embodiment, the current- splitting conductor 1 126 is formed as a planar conductive body. The current-splitting conductor 1 126 may be deposited as a planar conductive trace on one or more sub-layers of the substrate 1 102 (shown in Figure 8) that are disposed between the upper surface 1 106 (shown in Figure 8) and the lower surface 1 104 (shown in Figure 8). Alternatively, the current-splitting conductor 1126 may be located on the upper surface 1 106 or lower surface 1 104 of the substrate 1 102.
[0081] In the illustrated embodiment, the current-splitting conductor 1 126 extends below the ferrite body 1 1 16 and at least a portion of the opening 1 1 18 in the ferrite body 1 1 16. For example, at least part of the current-splitting conductor 1 126 may be located between the ferrite body 1 1 16 and the lower surface 1 104 (shown in Figure 8) of the substrate 1 102 (shown in Figure 8) along or parallel to the vertical direction 1 120 (shown in Figure 8) and at least part of the current-splitting conductor 1 126 may be between the opening 1 1 18 and the lower surface 1 104 of the substrate 1 102 along the vertical direction 1 120. As shown in Figure 8, the input conductor 1 1 10 and the current-splitting conductor 1 126 are disposed on opposite sides of the ferrite body 1 1 16.
[0082] One or more conductive current- splitting vias 1 128, 1 130 are coupled with the current- splitting conductor 1 126. The current-splitting vias 1 128, 1 130 include holes or channels that extend through the substrate 1 102 (shown in Figure 8) and that are plated or substantially filled with a conductive material (e.g., a metal, metal alloy, or conductive solder). As shown in Figure 9, the current-splitting vias 1 128, 1 130 are disposed outside of the ferrite body 1 1 16. For example, the current-splitting vias 1 128, 1 130 are not located inside the opening 1 1 18 of the ferrite body 1 1 16 in the illustrated embodiment. The current- splitting vias 1 128 are grouped in a first set 1200 (shown in Figure 9) on one side of the ferrite body 1 1 16 while the current-splitting vias 1130 are grouped in a different second set 1202 (shown in Figure 9) that is spaced apart from the first set 1200 on the opposite side of the ferrite body 1 1 16. As shown in Figure 9, the first and second sets 1200, 1202 may include non-overlapping groups of the current-splitting vias 1 128, 1 130. For example, the first and second sets 1200, 1202 may not share or include one or more of the same current- splitting vias 1 128, 1 130. Alternatively, the current-splitting vias 1 128 and/or 1 130 may be grouped into a different number of sets 1200, 1202.
[0083] In the illustrated embodiment, the device 1 100 includes ten current- splitting vias 1 128, 1 130 with five current-splitting vias 1 128 or 1 130 in each set 1200, 1202 (shown in Figure 9) disposed on opposite sides of the ferrite body 1 1 16. Alternatively, a different number of current- splitting vias 1 128 and/or 1 130 may be provided. The current- splitting vias 1 128, 1 130 vertically extend through the substrate 1 102 (shown in Figure 8) from the current-splitting conductor 1 126 toward the upper surface 1 106 (shown in Figure 8) of the substrate 1 102. In the illustrated embodiment, the current-splitting conductor 1 126 and the current-splitting vias 1 128, 1 130 can provide a portion of the conductive pathway 1002
(shown in Figure 7) that is represented by the current-splitting section 1006 in Figure 7. For example, the current- splitting conductor 1 126 and the current-splitting vias 1 128, 1 130 may provide the plurality of conductive pathways 1002 that are coupled with and split off of the conductive pathway 1002 in the input section 1004 of Figure 7. The current-splitting conductor 1 126 and the current-splitting vias 1 128, 1 130 may divide the electric current (I) received from the input conductor 1 1 10 and the input vias 1 124 into the first and second current fractions (Ii and I2).
[0084] The device 1100 includes a current-combining conductor 1 134 that is conductively coupled with the separate sets 1200, 1202 (shown in Figure 9) of the current- splitting vias 1 128, 1 130. The current-splitting vias 1 128, 1 130 conductively couple the current-splitting conductor 1 126 with the current-combining conductor 1 134. In the illustrated embodiment, the current-combining conductor 1 134 is formed as a planar conductive body. The current-combining conductor 1 134 may be deposited as a planar conductive trace on one or more sub-layers of the substrate 1 102 (shown in Figure 8) that are disposed between the upper surface 1 106 (shown in Figure 8) and the lower surface 1 104 (shown in Figure 8). Alternatively, the current-combining conductor 1 134 may be located on the upper surface 1 106 or lower surface 1 104 of the substrate 1 102.
[0085] In the illustrated embodiment, the current-combining conductor 1 134 extends above the ferrite body 1 1 16 and at least a portion of the opening 1 1 18 in the ferrite body 1 1 16. For example, at least part of the current-combining conductor 1 134 may be located between the ferrite body 1 1 16 and the upper surface 1106 (shown in Figure 8) of the substrate 1 102 (shown in Figure 8) along or parallel to the vertical direction 1 120 (shown in Figure 8) and at least part of the current-combining conductor 1 134 may be between the opening 1 1 18 and the upper surface 1 106 of the substrate 1102 along the vertical direction 1 120. As shown in Figure 8, the current-splitting conductor 1 126 and the current-combining conductor 1 134 are disposed on opposite sides of the ferrite body 1 1 16.
[0086] One or. more conductive current-combining vias 1 132 are coupled with the current-combining conductor 1 134 and the current-splitting conductor 1 126. The current- combining vias 1 132 include holes or channels that extend through the substrate 1 102 (shown in Figure 8) and that are plated or substantially filled with a conductive material (e.g., a metal, metal alloy, or conductive solder). As shown in Figure 9, the current-combining vias
1132 are disposed inside the ferrite body 1 1 16. For example, the current-combining vias 1 132 are located inside the opening 1 1 18 of the ferrite body 1 1 16. In the illustrated embodiment, the device 1 100 includes seven current-combining vias 1 132. Alternatively, a different number of current-combining vias 1 132 may be provided.
[0087] In one embodiment, holes or interior cavities in the substrate 1 102 (shown in Figure 8) are preformed or premade. For example, the holes or cavities may be formed when the substrate 1 102 is created. The holes or cavities can include posts that are positioned and shaped within the holes or cavities for the ferrite body 1 1 16 to reside on. The ferrite body 1 1 16 can be mechanically shaken into position within the substrate 1 102 and on top of the post in a hole or cavity by using a tapered insert that guides the ferrite body 1 1 16 into the hole. Alternatively, the ferrite body 1 1 16 can be placed into the hole and on the post with a pick-and-place machine. The post can provide a supporting framework for the structure. In one embodiment, a low stress or ultra low-stress material, such as silicone, can be inserted into the hole or cavity and surround the ferrite body 1 1 16. In one embodiment, if the device 11 10 is used for relatively high voltage and/or current applications, a special grade material may be used for substrate and/or post. The material can have relatively low amounts of halogens and/or be relatively glass bundle-free for increased reliability, as well as providing an encapsulation around the ferrite body 1 116 that is hermetic or near hermetic. Examples of such a material can include liquid crystalline polymer (LCP) and/or teflon. The vias 1 132 can extend through the substrate 1 102 and/or the low-stress material around the ferrite body 1 1 16 and may carry relatively large amounts of electric power. The substrate 1 102 can provide relatively high electric isolation between the vias 1 132 even in the presence of moisture and high temperatures.
[0088] The current-combining conductor 1 134 and the current-combining vias 1 132 can provide a portion of the conductive pathway 1002 (shown in Figure 7) that is represented by the current-combining section 1010 in Figure 7. For example, the current- combining conductor 1 134 and the current-combining vias 1 132 may combine the first and second current fractions (Ils I2) that are separately conveyed through the current- splitting vias 1 128, 1 130 around the ferrite body 1 1 16 to the current-combining conductor 1134.
[0089] The device 1 100 includes an output conductor 1 136 that receives the current (I) that is combined from the first and second current fractions (Ii, I2) by the current-
combining conductor 1 134. In the illustrated embodiment, the output conductor 1 136 is formed as a planar conductive body. The output conductor 1 136 may be deposited as a planar conductive trace on one or more sub-layers of the substrate 1 102 (shown in Figure 8) that are disposed between the upper surface 1 106 (shown in Figure 8) and the lower surface 1104 (shown in Figure 8). ' ~
[0090] As shown in Figure 9, the output conductor 1 136 extends below the ferrite body 1 1 16 and at least a portion of the opening 1 1 18 in the ferrite body 1 1 16. For example, at least part of the output conductor 1 136 may be located between the ferrite body 1 1 16 and the lower surface 1 104 (shown in Figure 8) of the substrate 1 102 (shown in Figure 8) along or parallel to the vertical direction 1 120 (shown in Figure 8) and at least part of the output conductor 1 136 may be between the opening 1 1 18 and the lower surface 1 104 of the substrate 1 102 along the vertical direction 1 120. Alternatively, at least part of the output conductor 1 136 may be located between the ferrite body 1 1 16 and the upper surface 1 106 (shown in Figure 8) of the substrate 1 102 along or parallel to the vertical direction 1 120 and at least part of the output conductor 1 136 may be between the opening 1 1 18 and the upper surface 1 106 of the substrate 1102 along the vertical direction 1 120.
[0091] A conductive bus 1 138 and/or a conductive bus 1 140 (shown in Figure 8) may be coupled with the output conductor 1 136 and exposed at or along the lower surface 1104 and the upper surface 1 106, respectively, of the substrate 1 102. Conductive vias 1 142 can couple the buses 1 138, 1 140 with each other. Alternatively, the output conductor 1 136 may be located on the upper surface 1 106 or lower surface 1 104 of the substrate 1 102. The conductive bus 1 138 and/or 1 140 outputs the electric current (I) that is combined from the first and second current fractions I2) from the device 1 100. A circuit may be conductively coupled with one or more of the busses 1138, 1 140 to receive the combined current (I).
[0092] In operation, the device 1 100 receives electric current (I) from an electric circuit and conveys the current (I) along the input conductor 1 1 10 to the input vias 1 124. The input vias 1 124 convey the current (I) through the opening 1 1 18 in the ferrite body 1 1 16. The current (I) flows through the input vias 1 124 to the current-splitting conductor 1 126. The current-splitting conductor 1 126 divides the current (I) into the first and second current fractions (Ii, I2). The first current fraction (Ii) is conveyed by the first set 1200 of current- splitting vias 1128 outside of the ferrite body 1 1 16 and the second current fraction (I2) is
conveyed by the second set 1202 of current-splitting vias 1 130 outside of the ferrite body 1 1 16. The current-splitting vias 1 128, 1 130 conduct the current fractions (Il s I2) to the current-combining conductor 1 134. The flow of the current fractions (Ij, I2) through the current-splitting conductor 1 126 and the current-splitting vias 1 128, 1 130 to the current- combining conductor 1 134 approximately follows the flow of current through coils that helically encircle the ferrite body 1 1 16. The current fractions (Il3 I2) are received by the current-combining conductor 1 134 and combined into the current (I). The current (I) is conveyed from the current-combining conductor 1134 to the output conductor 1 136 by the current-combining vias 1 132.
[0093] Figure 10 is a perspective view of a planar inductor device 1300 in accordance with another embodiment. The device 1300 may be similar to the device 1 100 shown in Figures 8 and 9. For example, the device 1300 may include the busses 1 1 12, 1 1 14, 1 138, 1 140, the conductors 1 110, 1 126, 1 134, 1 136, the vias 1 124, 1 128 (shown in Figure 9), 1 130, 1 132, and/or the ferrite body 1 1 16 embedded in the substrate 1 102. One difference between the device 1 100 and the device 1300 is that the device 1300 may include additional conductive pathways 1302, 1304. In the illustrated embodiment, the conductive pathways 1302, 1304 represent wires that are coupled with the device 1300 by wire bonding. Alternatively, the conductive pathways 1302, 1304 may represent other conductors, such as conductive traces, busses, and the like.
[0094] The conductive pathways 1302 are coupled with the bus 1 1 12 and one or more of the input conductor 1 1 10 and/or the input vias 1 124. In one embodiment, the conductive pathways 1302 are wire bonds that are coupled to the bus 1 1 12 and the interfaces between the input conductor 1 1 10 and the input vias 1 124. The conductive pathways 1302 provide additional pathways for the current (I) to be conveyed from the bus 1 1 12 to the input vias 1 124. As shown in Figure 10, current (I) that is received by the bus 1 1 12 can be conveyed to the input vias 1 124 by the input conductor 1 1 10 and the conductive pathways 1302. Providing the conductive pathways 1302 can reduce the resistance of the path that the current (I) experiences and/or power losses that may otherwise occur when the current (I) flows to the input vias 1 124. Although not shown in Figure 10, conductive pathways that are similar to the conductive pathways 1302 and/or 1304 may be joined to one or more of the conductors 1 126, 1 136,
[0095] The conductive pathways 1304 are coupled with the current-combining conductor 1 134 in a plurality of locations. For example, the conductive pathways 1304 may be coupled to the interfaces between the current-combining conductor 1 134 and the current- combining vias 1 132 and coupled to the current-combining conductor 1134 in locations that are spaced apart from the interfaces between the current-combining conductor 1 134 and the current-combining vias 1 132. The conductive pathways 1304 provide additional pathways for the current fractions (Ii, I2) to be conveyed from the current-combining conductor 1 134 to the current-combining vias 1 132. Providing the conductive pathways 1304 can reduce the resistance of the path that the current fractions (Ii, I2) experience and/or power losses that may otherwise occur when the current fractions (Ij, I2) are combined into the current (I) by the current-combining conductor 1 134 and/or the current-combining vias 1 132.
[0096] Figures 21 through 23 illustrate different techniques for conductively coupling conductors and/or conductive layers in one or of the embodiments described herein. For example, the techniques illustrated in Figures 21 through 23 may be used to conductively couple two or more of the conductors 1 1 10, 1 126, 1134, 1 136 (shown in Figure 8) of the device 1 100 (shown in Figure 8) and/or of the device 1300 (shown in Figure 10).
[0097] With respect to Figure 21 , conductive layers or conductors 2400, 2402 and conductive layers or conductors 2404, 2406 are coupled with each other using conductive microvias 2408. In another embodiment, conductive couplings between conductive layers or conductors 2400, 2402 and/or between conductive layers or conductors 2404, 2406 disposed on different layers of a substrate can represent portions of through holes that extend through the entire thickness of the substrate. The view shown in Figure 21 is an exploded view with the conductors 2400, 2402 separated from the conductors 2404, 2408. The conductors 2400, 2404 may be edge-coupled conductors that are joined along edges 2410, 2412 that face each other and the conductors 2402, 2406 may be edge-coupled and/or offset broadside coupled conductors that are joined along edges 2414, 2416 that face each other. The coupling of the conductors 2400, 2402 and of the conductors 2404, 2406 with the microvias 2408 can increase the amount of electric current that may be conveyed using the conductors 2400, 2402, 2404, 2406 and/or can modify inductive coupling between the conductors 2400, 2402, 2404, 2406.
[0098] With respect to Figure 22, conductive layers or conductors 2500, 2502, 2504 are conductively coupled in a plurality of manners. The view shown in Figure 22 is an exploded view with the conductors 2502, 2504 separated from the conductor 2500. For example, the conductor 2500 can be edge-coupled with the conductors 2502, 2504. The conductors 2502, 2504 are conductively coupled with each other by a wire bond 2506.
[0099] With respect to Figure 23, conductive layers or conductors 2600, 2602 are edge-coupled conductors. The view shown in Figure 23 is an exploded view with the conductors 2600, 2602 separated from each other. Each of the conductors 2600, 2602 includes a wire bond 2604, 2606 that is coupled with the corresponding conductor 2600, 2602 in a plurality of locations. The addition of the wire bonds 2604, 2606 can increase the current-carrying capability of the conductors 2600, 2602.
[00100] Figure 1 1 is a top view of a ferrite body 1400 in accordance with one embodiment. The ferrite body 1400 may be used as the ferrite body in one or more embodiments described herein. For example, the ferrite body 1400 may be used as the ferrite body 1 10 (shown in Figure 1), the ferrite body 310 (shown in Figure 3), the ferrite body 510 (shown in Figure 5), the ferrite body 1016 (shown in Figure 7), or the ferrite body 1 1 16 (shown in Figure 8). With respect to the ferrite bodies 1 10, 310, 510, these bodies 1 10, 310, 510 may represent a section of portion of the ferrite body 1400. For example, one or more of the ferrite bodies 110, 310, 510 may represent a subsection of the ferrite body 1400 shown in Figure 1 1.
[00101] The ferrite body 1400 may include, or be formed from, a metal and/or a magnetic material. In one embodiment, the ferrite body 1400 includes, or is formed from, a relatively soft ferrite such as NiZn or MnZn. Alternatively, a different metal or metal alloy may be used. The ferrite body 1400 has a toroid or anulus shape that encircles a central opening 1402 in the illustrated embodiment. Alternatively, the ferrite body 1400 may have another shape. The ferrite body 1400 is divided into a plurality of sections 1404, 1406. For example, the ferrite body 1400 may have two U-shaped sections 1404, 1406, with the section 1404 extending along an arcuate path between opposite ends 1408, 1410 and the section 1406 extending along an arcuate path between opposite ends 1412, 1414.
[00102] In the illustrated embodiment, the ends 1408, 1410 of the section 1404 face the ends 1412, 1414 of the section 1406. The ends 1408 and 1412 and the ends 1410
and 1414 are separated from each other by a buffer layer 1416. The buffer layers 1416 separate the sections 1404, 1406 from each other. The buffer layers 1416 may be formed from a non-conductive and/or non-magnetic material. For example, the buffer layers 1416 may be formed from dielectric materials, such as epoxy.
[00103] The buffer layers 1416 can separate the ferrite body 1400 into the sections 1404, 1406 to reduce saturation of the ferrite body 1400. For example, when one or more conductive coils helically wrap around the ferrite body 1400 and convey current around the ferrite body 1400 (such as in one or more of the devices 100, 300, 500, 1000, 1 100, 1300 shown and described above), the current may generate sufficiently high magnetic flux in the ferrite body 1400 that the ferrite body 1400 becomes saturated. The ferrite body 1400 may be saturated when further increases in the electric current that is conveyed in conductive coils encircling the ferrite body do not result in a corresponding increase in the magnetic flux in the ferrite body 1400. The buffer layers 1416 separate the sections 1404, 1406 of the ferrite body 1400 such that magnetic flux in the ferrite body 1400 cannot flow between the sections 1404, 1406. As a result, the magnetic flux in the ferrite body 1400 may be decreased for. relatively large current flowing around the ferrite body 1400.
[00104] In one embodiment, the ferrite body 1400 is cut into the sections 1404, 1406 after the ferrite body 1400 is disposed within a substrate. For example, after an electric circuit is formed that includes a conductive coil helically wrapped around the ferrite body 1400, a punch machine or saw plate can be used to cut through a portion of ferrite body 1400 that is already embedded in a substrate with relatively high precision and accuracy. There can be one or numerous cuts through the ferrite body 1400. For example, the ferrite body 1400 may be embedded into a substrate in a manner as described in U.S. Patent Application No. 13/028,949, which is entitled "Planar Electronic Device Having A Magnetic Component And Method For Manufacturing The Electronic Device" and was filed on 16-February-201 1 (referred to herein as the "'949 Application"). The entire disclosure of the '949 Application is incorporated by reference herein in its entirety. In connection with the description of the '949 Application, the ferrite body 1400 may be embedded in the encapsulating material 304 of the substrate 104 of the '949 Application in a manner similar to the ferrite body 200 of the '949 Application.
[00105] In another embodiment, mechanically pressure may be applied to the substrate that includes the ferrite body 1400 to create cracks or fractures in the ferrite body 1400. For example, pressure may be applied to provide enough force that the ferrite body 1400 develops a fixed amount of hairline cracks through the ferrite body 1400. Because the ferrite body 1400 is a continuous shape in the illustrated embodiment, the application of pressure may develop cracks on opposite ends of the ferrite body 1400 to convert the ferrite body 1400 from a continuous to non-continuous body.
[00106] Figure 12 is a top view of a multilayer inductor device 1500 in accordance with one embodiment. Similar to the substrate 102 (shown in Figure 1) of the device 100 (shown in Figure 1), the device 1500 includes a substrate 1502 having a thickness dimension that vertically extends from a lower surface (not shown in Figure 12) that is similar to the lower surface 106 (shown in Figure 1) to an opposite upper surface 1504. The thickness dimension may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension may be a larger distance. The substrate 1502 can be formed from a plurality of dielectric layers 1700 (shown in Figure 14) that are vertically stacked on top of each other. As shown in Figure 12, the dielectric layers 1700 can be oriented parallel to each other. The device 1500 includes a ferrite body 1506 that may be entirely disposed within the thickness dimension of the substrate 1502. In the illustrated embodiment, the ferrite body 1506 has a toroid or anulus shape that extends around an interior opening 1508. Alternatively, the ferrite body 1506 may have a different shape.
[00107] With continued reference to Figure 12, Figure 13 is a perspective view of the device 1500 with the substrate 1502 not shown in Figure 13. Figure 14 is an exploded view of the device 1500. The ferrite body 1506 is not shown in Figure 14. The substrate 1502 may be a multilayer body that includes several dielectric layers 1700 (shown in Figure 14) that are sandwiched on one another. For example, the substrate 1502 may include several layers of FR-4 and/or epoxy material that form the various dielectric layers 1700. The dielectric layers 1700 are individually referred to with the reference number 1700 and are individually referred to by the reference numbers 1700A, 1700B, 1700C, and 1700D. While only four dielectric layers 1700 are shown in Figure 14, alternatively, several more dielectric layers 1700 may be provided. For example, a plurality of dielectric layers 1700 may be provided between the dielectric layers 1700A and 1700B, between the dielectric layers
1700B and 1700C, and/or between the dielectric layers 1700C and 1700D. In the illustrated embodiment, several dielectric layers 1700 are provided between the dielectric layers 1700B and 1700C. The dielectric layers 1700 between the dielectric layers 1700B and 1700C may include openings to form a cavity that receives the ferrite body 1506, as described above.
[00108] The device 1500 includes several conductors 1510, 1600, 1602, 1604 and conductive vias 1512, 1514, 1606, 1608. The conductors 1510, 1600, 1602, 1604 are shown as conductive layers, such as conductive traces. Alternatively, and as described below, the conductors 1510, 1600, 1602, 1604 may include one or more other conductive bodies, such as wire bonds. The conductors 1510 may be referred to as outer upper conductors 1510 that are disposed at or near the upper surface 1504 (shown in Figure 12) of the substrate 1502. For example, the outer upper conductors 1510 may include conductive traces that are deposited on the upper surface 1504 of the substrate 1502 or on the dielectric layer 1700A that is located beneath the upper surface 1504. The outer upper conductors 1510 are generally referred to by the reference number 1510 and are individually referred to by the reference numbers 1510A, 1510B, 15 IOC, and so on. In one embodiment, one or more of the conductors 1510, 1600, 1602, 1604 can be combined with wire bonds and/or replaced with wire bonds, similar to as described below in connection with Figures 15, 19, and/or 20. The conductors 1602 may be referred to as outer lower conductors 1602 that are disposed at or near the lower surface of the substrate 1502 (shown in Figure 12), such as at or near the lower surface 106 (shown in Figure 1) of the substrate 102 (shown in Figure 1). For example, the outer lower conductors 1602 may include conductive traces that are deposited on the lower surface of the substrate 1502 or on the dielectric layer 1700D that is located above the lower surface. The outer lower conductors 1602 are generally referred to by the reference number 1602 and are individually referred to by the reference numbers 1602 A, 1602B, 1602C, and so on.
[00109] The conductors 1600 may be referred to as inner upper conductors 1600 that are disposed within the substrate 1502. For example, the inner upper conductors 1600 may include conductive traces that are deposited on the dielectric layer 1700B, with the dielectric layer 1700B disposed between the dielectric layer 1700 A having the outer upper conductors 1510 and the lower surface of the substrate 1502. The inner upper conductors 1600 are generally referred to by the reference number 1600 and are individually referred to by the reference numbers 1600A, 1600B, 1600C, and so on.
[001 10] The conductors 1604 may be referred to as inner lower conductors 1604 that are disposed within the substrate 1502. For example, the inner lower conductors 1604 may include conductive traces that are deposited on the dielectric layer 1700C, with the dielectric layer 1700C disposed between the dielectric layer 1700D having the outer lower conductors 1602 and the dielectric layer 1700B having the inner upper conductors 1600. The inner lower conductors 1604 are generally referred to by the reference number 1604 and are individually referred to by the reference numbers 1604 A, 1604B, 1604C, and so on.
[001 1 1] The vias 1512, 1514, 1606, 1608 vertically extend through the substrate 1502 to conductively couple the conductors 1510, 1600, 1602, 1604. The vias 1512 may be referred to as a first inner set of interior vias 1512 that are disposed inside the opening 1508 of the ferrite body 1506. The interior vias 1512 conductively couple the outer upper conductors 1510 with the outer lower conductors 1602. The vias 1514 may be referred to as a first outer set of exterior vias 1514 that are disposed outside of the ferrite body 1506. For example, the vias 1512 and the vias 1514 may be located on opposite sides of the ferrite body 1506. The exterior vias 1514 conductively couple the outer upper conductors 1510 with the outer lower conductors 1602. The interior vias 1512 are generally referred to by the reference number 1512 and are individually referred to by the reference numbers 1512A, 1512B, 1512C, and so on. The exterior vias 1514 are generally referred to by the reference number 1514 and are individually referred to by the reference numbers 1514A, 1514B, 1514C, and so on.
[001 12] The vias 1606 may be referred to as a second inner set of interior vias 1606 that are disposed inside the opening 1508 of the ferrite body 1506. The interior vias 1606 conductively couple the inner upper conductors 1600 with the inner lower conductors 1604. The vias 1608 may be referred to as a second outer set of exterior vias 1608 that are disposed outside of the ferrite body 1506. For example, the interior vias 1606 and the exterior vias 1608 may be located on opposite sides of the ferrite body 1506. The exterior vias 1608 conductively couple the inner upper conductors 1600 with the inner lower conductors 1604. The interior vias 1606 are generally referred to by the reference number 1606 and are individually referred to by the reference numbers 1606 A, 1606B, 1606C, and so on. The exterior vias 1608 are generally referred to by the reference number 1608 and are individually referred to by the reference numbers 1608 A, 1608B, 1608C, and so on
[001 13] The conductors 1510, 1600, 1602, 1604 and the vias 1512, 1514, 1606, 1608 are conductively coupled to form one or more conductive coils that helically extend around the ferrite body 1506. For example, the conductors 1510, 1600, 1602, 1604 and the vias 1512, 1514, 1606, 1608 can form inner and outer conductive coils 1610, 1612 that helically wrap around the ferrite body 1506 such that each coil 1610, 1612 extends through the opening 1508 in the ferrite body 1506 and wraps around the exterior of the ferrite body 1506 before returning into the opening 1508 of the ferrite body 1506. The conductive coils 1610, 1612 are not conductively coupled with each other in one embodiment. For example, the conductive coils 1610, 1612 may not have a common conductive body that is coupled to each of the conductive coils 1610, 1612. The conductive coils 1610, 1612 may be capable of inductively transferring electric energy from one coil 1610 or 1612 to the other coil 1612 or 1610, such as in a transformer or choke.
[001 14] In one embodiment, the outer upper conductors 1510, the outer lower conductors 1602, the first inner vias 1512, and the first outer vias 1514 form the outer conductive coil 1612 and the inner upper conductors 1600, the inner lower conductors 1604, the second inner vias 1606, and the second outer vias 1608 form the inner conductive coil 1610. The outer conductors 1510, 1602 may be elongated in directions that are obliquely oriented, or angled, with respect to each other. The first inner and outer vias 1512, 1514 can be coupled with different outer conductors 1510, 1602 to form the outer conductive coil 1612. As shown in Figure 14, for example, the outer upper conductor 1510A can be conductively coupled with the interior via 1512A. The first inner via 1512A conductively couples the outer upper conductor 151 OA with the outer lower conductor 1602 A. The outer lower conductor 1602 A also is conductively coupled with the exterior via 1514A. The first outer via 1514A is conductively coupled with the outer upper conductor 1510B. The outer upper conductor 1510B is conductively coupled with the first inner via 1512B. The first inner via 1512B conductively couples the outer upper conductor 1510B with the outer lower conductor 1602B. The progression of the first inner and outer vias 1512, 1514 coupling different outer upper conductors 1510 with different outer lower conductors 1602 continues to form the helical outer conductive coil 1612. In the illustrated embodiment, the outer conductive coil 1612 helically wraps around the ferrite body 1506 twelve times. Alternatively, the outer conductive coil 1612 helically wraps around the ferrite body 1506 a different number of times.
[001 15] Similarly, the second inner and outer vias 1606, 1608 can be coupled with different inner conductors 1600, 1604 to form the inner conductive coil 1610. As shown in Figure 14, for example, the inner upper conductor 1600A can be conductively coupled with the second inner via 1606A. The second inner via 1606A conductively couples the inner upper conductor 1600A with the inner lower conductor 1604A. The inner lower conductor 1604A is coupled with the second inner via 1606A and with the second outer via 1608A. The second outer via 1608 A conductively couples the inner lower conductor 1604A with a different inner upper conductor 1600B. The inner upper conductor 1600B is coupled with a different inner via 1606B, which is coupled with a different inner lower conductor 1604B. This progression of the inner and outer vias 1606, 1608 coupling different inner upper conductors 1600 with different inner lower conductors 1604 continues to form the helical inner conductive coil 1610. In the illustrated embodiment, the inner conductive coil 1610 helically wraps around the ferrite body 1506 thirty-two times. Alternatively, the inner conductive coil 1612 helically wraps around the ferrite body 1506 a different number of times.
[001 16] The conductive coils 1610, 1612 can provide inductive components for an electronic circuit. For example, one or more conductive traces, wires, or other bodies may be coupled with the conductive coils 1610, 1612 to form a transformer (e.g., where the conductive coils 1610, 1612 inductively pass electric current between two circuits), a choke, balun, or other component. When constructing different inductive elements such as transformer, balun, inductor, chokes, and the like, such as the device 1600, one or more techniques for conductively coupling conductors or conductive layers as shown in Figures 21 through 23 and described above. In the case of a transformer device that is used for DSL and/or Ethernet applications, the dielectric separation between conductors can provide relatively large dielectric voltage isolation, such as electric isolation at voltages of up to 5000 V. Alternatively, the dielectric separation can provide relatively large dielectric voltage isolation at other voltages.
[001 17] Figure 15 is a cross-sectional view of another embodiment of a planar inductor device 1800. The device 1800 may be similar to the device 1500 shown in Figures 12 through 14. For example, the device 1800 may include a planar substrate 1802 having a toroid or annulus shaped ferrite body 1804 disposed within the substrate 1802 and one or more conductive coils 1806 helically wrapping around the ferrite body 1804, The substrate
1802 extends between opposite upper and lower surfaces 1808, 1810. An interior cavity 1812 is disposed within the substrate 1802 between the upper and lower surfaces 1808, 1810. The ferrite body 1804 is located within the cavity 1812. In the illustrated embodiment, the cavity 1812 is filled or substantially filled with a dielectric material 1814, such as a flexible epoxy material, such that the dielectric material 1814 at least partially encloses the ferrite body 1804 in the cavity 1812. Alternatively, the cavity 1812 may be filled or substantially filled with air or another gas, such that the air or gas at least partially surrounds the ferrite body 1804 in the cavity 1812.
[001 18] In the illustrated embodiment, lower conductive layers 1816 are disposed on the lower surface 1810 of the substrate 1802. For example, the lower conductive layers 1816 may be conductive traces deposited on the lower surface 1810. Conductive vias 1822 are coupled with the lower conductive layers 1816 and vertically extend through the substrate 1802. The vias 1822 can be filled with conductive paste or with another conductive or non- conductive filling material such that the vias 1822 can be capped. Conductive caps 1818 are disposed on the upper surface 1808 of the substrate 1802 and are conductively coupled with the vias 1822. As shown in Figure 15, the conductive caps 1818 are spaced apart from each other such that the conductive caps 1818 do not contact each other on the upper surface 1808 of the substrate 1802. The conductive vias 1822 may be filled with a conductive material, such as a metal, metal alloy, solder, or other conductive body, that is coupled with the conductive caps 1818.
[001 19] Wire bonds 1820 are conductively coupled with the conductive caps 1818 to provide conductive pathways between the caps 1818. The wire bonds 1820 are elongated conductive bodies, such as conductive wires. In one embodiment, the wire bonds 1820 are formed from 10 micrometer to 50 micrometer diameter sized gold wires. Alternatively, a different sized wire and/or different material may be used as the wire bonds 1820.
[00120] The conductive coil 1806 forms several turns around the ferrite body 1804. In the illustrated embodiment, the turns of the coil 1806 are formed by the vias 1822, the lower conductive layers 1816, the caps 1818, and the wire bonds 1820. A dielectric overmold layer 1824 can be provided above the upper surface 1808 of substrate 1802. The overmold layer 1824 covers or encapsulates the wire bonds 1820 and caps 1818. For example, the wire bonds 1820 may be entirely disposed within the overmold layer 1824. The
overmold layer 1824 can provide voltage isolation. In another embodiment, wire bonds may be used in place of or in addition to the lower conductive layers 1816.
[00121] In the illustrated embodiment, conductive access to the device 1800 is provided by conductive terminals 1826 that extend through the overmold layer 1824. For example, openings or vias may be formed through the overmold layer 1824 using laser vias and/or mechanical vias. A conductive body may be deposited into the openings or vias that are conductively coupled with one or more of the caps 1818 to form the conductive terminals 1826.
[00122] Figure 19 is a cross-sectional view of another embodiment of a planar inductor device 2200. The device 2200 may be similar to the device 1500 shown in Figures 12 through 14. For example, the device 2200 may include a planar substrate 2202 having a toroid or anulus shaped ferrite body 2204 disposed within the substrate 2202 and one or more conductive coils 2206 helically wrapping around the ferrite body 2204. The substrate 2202 extends between opposite upper and lower surfaces 2208, 2210. An interior cavity 2212 is disposed within the substrate 2202 and the ferrite body 2204 is located within the cavity 2212. In one embodiment, the interior cavities 2212 can be premade (e.g., formed when the substrate 2202 is created) and/or include posts for the ferrite body 2204 to be disposed upon. The ferrite body 2204 can be mechanically shaken into position using a tapered insert that guides the ferrite body 2204 into the cavity 2212 and onto the post, or the ferrite body 2204 may be placed with a pick and place machine. Alternatively, another technique may be used. The post can provide a supporting framework for the device 2200. In one embodiment, a low stress or an ultra low-stress material, such as silicone, can be used to surround the ferrite body 2204, as described above. In one embodiment, if the device 2200 is used for relatively high voltage and/or current applications, a special grade material may be used for substrate and/or post. The material can have relatively low amounts of halogens and/or be relatively glass bundle-free for increased reliability, as well as providing an encapsulation around the ferrite body 2204 that is hermetic or near hermetic. Examples of such a material can include liquid crystalline polymer (LCP) and/or teflon. Conductive vias 2218 can extend through the substrate 2202 and/or the low-stress material around the ferrite body 2204 and may carry relatively large amounts of electric power. The substrate 2202 can provide relatively high electric isolation between the vias 2218 even in the presence of moisture and high temperatures.
[00123] In the illustrated embodiment, upper and lower conductive caps 2214, 2216 are disposed on the upper surface 2208 of the substrate 2202 and are conductively coupled with the conductive vias 2218 that extend through the substrate 2202. The upper conductive caps 2214 can be spaced apart from each other such that the upper conductive caps 2214 do not contact each other and/or the lower conductive caps 2216 can be spaced apart from each other such that the lower conductive caps 2216 do not contact each other. The vias 2218 may be filled with a conductive material, such as a metal, metal alloy, solder, or other conductive body, that is coupled with the upper and lower conductive caps 2214, 2216.
[00124] Upper and lower wire bonds 2220, 2222 are conductively coupled with the upper and lower conductive caps 2214, 2216, respectively, to provide conductive pathways between the upper conductive caps 2214 and between the lower conductive caps 2216. Similar to the wire bonds 1820 (shown in Figure 15), the wire bonds 2220, 2222 are elongated conductive bodies, such as conductive wires. The conductive coil 2206 forms several turns around the ferrite body 2204. In the illustrated embodiment, the turns of the coil 2206 are formed by the vias 2218, the lower conductive caps 2216, the lower wire bonds 2222, the upper conductive caps 2214, and the upper wire bonds 2220. Upper and/or lower dielectric overmold layers 2224, 2226 can be provided to cover or encapsulate the upper and/or lower wire bonds 2220, 2222 and upper and/or lower conductive caps 2214, 2216.
[00125] Figure 20 is a cross-sectional view of another embodiment of a planar inductor device 2300. The device 2300 may be similar to the device 1500 shown in Figures 12 through 14 and the device 2200 shown in Figure 19. For example, the device 2300 may include a planar substrate 2302, a toroid or anulus shaped ferrite body 2304, and one or more conductive coils 2306 helically wrapping around the ferrite body 2304. In the illustrated embodiment, the substrate 2302 includes several interior conductive layers 2308 disposed within the thickness of the substrate 2302. The interior conductive layers 2308 may include one or more conductive traces located within the substrate 2302. The substrate 2302 also includes conductive vias 2310 that may be similar to the vias 2218 (shown in Figure 19), upper and lower conductive caps 2320, 2322 that may be similar to the upper and lower conductive caps 2214, 2216 (shown in Figure 19), and upper and lower wire bonds 2324, 2326 that may be similar to the upper and lower wire bonds 2220, 2222 (shown in Figure 19).
[00126] One difference between the devices 2200 and 2300 is that the wire bonds 2324, 2326 of the device 2300 are conductively coupled with one or more of the interior conductive layers 2308 by microvias 2328 in the substrate 2302. The microvias 2328 can include channels or holes in the substrate 2302 that are filled and/or plated with conductive materials, such as metals, metal alloys, and the like. The microvias 2328 may not entirely extend through the thickness of the substrate 2302, as shown in Figure 20. For example, the microvias 2328 may only partially extend through the substrate 2302 between two or more interior conductive layers 2308 and/or between an interior conductive layer 2308 and an upper or lower conductive cap 2320, 2322.
[00127] Figure 16 is a cross-sectional view of another embodiment of a planar inductor device 1900. The device 1900 may be similar to the device 1500 shown in Figures 12 through 14. For example, the device 1900 may include a planar substrate 1902 having a toroid or anulus shaped ferrite body 1904 disposed within the substrate 1902 and one or more conductive coils 1906 helically wrapping around the ferrite body 1904. The substrate 1902 extends between opposite upper and lower surfaces 1908, 1910. An interior cavity 1912 is disposed within the substrate 1902 between the upper and lower surfaces 1908, 1910. The ferrite body 1904 is located within the cavity 1912. Upper and lower conductive layers 1918, 1916 and conductive vias 1922 form the conductive coil 1906 that helically wraps around the ferrite body 1904, as described above.
[00128] In the illustrated embodiment, the cavity 1912 is filled or substantially filled with a flexible dielectric material 1914 that is mixed with and/or includes one or more relatively high permeability materials. A "high permeability" material may include a material having a magnetic relative permeability (μΓ) of at least 100. In one embodiment, the ferrite body 1904 may be at least partially surrounded by an epoxy material that is mixed with high permeability powders, such as nanopowders of cobalt, nickel, manganese, chromium, iron, and the like. In another embodiment, the ferrite body 1904 can not be provided and the cavity 1912 may be filled with the material 1914 mixed with the high permeability materials. The material 1914 and high permeability materials may replace the ferrite body 1904 in an inductor device that is formed by conductive coil 1906 helically wrapped around the material 1914 with the high permeability materials.
[00129] Upper and lower high permeability layers 1924, 1926 may be deposited outside of the substrate 1902 on the upper and lower surfaces 1908, 1910, respectively. The layers 1924, 1926 may be formed from a flexible dielectric material that is mixed with or includes one or more high permeability materials, similar to the material 1914 in the cavity 1912. The layers 1924, 1926 can reduce or prevent flux leakage from the device 1900 and/or increase the effective permeability of the device 1900.
[00130] Figure 17 is a cross-sectional view of another embodiment of the planar inductor device 1900 shown in Figure 16. In the illustrated embodiment, one or more planar ferrite slabs 2000 are disposed within the cavity 1912 in the substrate 1902. As shown in Figure 17, the slabs 2000 may be disposed above and below the ferrite body 1904. The slabs 2000 may be held in place by the material 1914 in the cavity 1912. The slabs 2000 may be planar bodies that are formed from or include a ferrite material, such as cobalt, nickel, manganese, chromium, iron, and the like. In one embodiment, the slabs 2000 may be ferrite material sheets that are 8 to 10 micrometers thick. Alternatively, the slabs 2000 may be a different thickness.
[00131] As shown in Figure 17, one or more of the slabs 2000 may be provided in the upper and/or lower layers 1924, 1926. For example, slabs 2000 that extend over a substantial portion of the upper and/or lower surfaces 1908, 1910 of the substrate 1902 may be held in the layers 1924, 1926. The slabs 2000 can further reduce or prevent flux leakage from the device 1900 and/or increase the effective permeability of the device 1900.
[00132] In one embodiment, one or more of the material 1914 having the high permeability material and/or the ferrite slabs 2000 may be provided in connection with one or more of the devices 100, 300, 500, 1 100, 1500 (shown in Figures 1 , 3, 5, 8, and 12). For example, one or more of the ferrite bodies 1 10, 310, 510, 1 1 16, 1506 (shown in Figures 1 , 3, 5, 8, and 12) may be disposed within a cavity that is filled or substantially filled with the dielectric material 1914 that includes high permeability materials and/or one or more of the slabs 2000.
[00133] Figure 24 is a side view of a planar inductor device 700 in accordance with another embodiment. The device 1800 may be similar to one ro more devices shown and described herein, such as the device 100 shown in Figure 1. For example, the device 700 includes a substrate 702 having a thickness dimension 704 that vertically extends from a
lower surface 706 to an opposite upper surface 708. The thickness dimension 704 may be relatively small, such as 2.5 millimeters or less, 2.0 millimeters or less, 1.0 millimeters or less, or another distance. Alternatively, the thickness dimension 704 may be a larger distance. The device 700 also includes a ferrite body 710 that may be entirely disposed within the thickness dimension 704 of the substrate 702. In one embodiment, the substrate 702 may include an interior cavity, such as the cavity 120 (shown in Figure 1) of the substrate 102 (shown in Figure 1), with the ferrite body 710 disposed in the cavity.
[00134] The substrate 702 can be formed from a plurality of dielectric layers 712 that are vertically stacked on top of each other. While only twelve layers 712 are shown in the illustrated embodiment, alternatively, a larger or smaller number of the layers 712 may be provided. The layers 712 include or are formed from a dielectric material, such as FR-4, cured epoxy, polytetrafluoroethylene, FR- 1, CEM-1, CEM-3, thermoplastics, spin-coated epoxies and the like. The layers 712 may be held together to form the substrate 702 by one or more adhesives, such as epoxy.
[00135] The ferrite body 710 is positioned within the substrate 702 such that the ferrite body 710 extends through several of the layers 712. The ferrite body 710 may be located within axially-aligned through holes 802 (shown in Figure 19) in the layers 712, while remaining entirely disposed within the thickness dimension 704 of the substrate 702. Alternatively, the ferrite body 710 may protrude outside of the thickness dimension 704 of the substrate 702, such as by projecting above a plane defined by the upper surface 708 and/or below a plane defined by the lower surface 706.
[00136] With continued reference to Figure 24, Figure 25 is an exploded view of one embodiment of a subset 800 of the layers 712 in the substrate 702. The subset 800 can include less than all of the layers 712 that are vertically stacked on each other in the substrate 702. The layers 712 are collectively referred to in Figure 25 by the reference number 712 and are individually referred to by the reference numbers 712 A, 712B, 712C, and 712D. While the description herein focuses on the subset 800 of layers 712, alternatively, the description may be applied to more than the four layers 712 in the subset 800. For example, the description of the layers 712A-D may apply to all of the layers 712 through which the ferrite body 710 extends inside of the substrate 702.
[00137] As shown in Figure 25 , the layers 712A-D include holes 802 that are axially aligned with each other along a center axis 810. The center axis 810 may be parallel to the direction in which the thickness dimension 704 of the substrate 702 is measured. The holes 802 are shaped to receive the ferrite body 710. For example, the holes 802 may have a circular shape with a diameter that is sufficiently large such that a cylindrical ferrite body 710 can be disposed within the holes 802. Alternatively, the holes 802 may have a different shape. The layers 712A-D encircle the ferrite body 710 in the planes defined by the respective layers 712A-D when the ferrite body 710 is disposed in the holes 802.
[00138] The layers 712A-D include conductors 804, 806 that partially extend around the ferrite body 710 within the respective layer 712A-D. The conductors 804, 806 may be formed as conductive traces or layers disposed on or in the layers 712A-D. As shown in Figure 25, each of the conductors 804, 806 encircles or extends around a portion of the hole 802 in the corresponding layer 712A-D. The conductor 804 or 806 in each layer 712 can extend around less than the entire outer periphery of the hole 802 in the same layer 712. In the illustrated embodiment, each of the conductors 804, 806 has an approximate shape of an arc that subtends approximately 180 degrees of the circumference of the hole 802. Alternatively, the conductors 804, 806 may have a different shape and/or subtend a different angle or extend around a different fraction of the outer periphery or circumference of the hole 802.
[00139] The conductors 804, 806 are coupled with conductive microvias 808. For example, each of the conductors 804, 806 may extend from a first microvia 808 to a second microvia 808 in the same layer 712 as the conductor 804, 806. As shown in Figure 24, the microvias 808 extend through the layers 712. The microvias 808 provide vertically oriented conductive pathways that extend through one or more of the layers 712 while the conductors 804, 806 provide horizontal conductive pathways within separate layers 712. In the illustrated embodiment, each of the conductors 804, 806 can provide a horizontal conductive pathway within a layer 712 while each of the microvias 808 provides a vertical conductive pathway or interconnect through the thickness of the layer 712. The microvias 808 are shown as buried vias as the microvias 808 are not exposed at the upper surface 708 or the lower surface 706 of the substrate 702. Alternatively, one or more of the microvias 808 may be exposed at the upper surface 708 or the lower surface 706 of the substrate 702.
[00140] The micro vias 808 in the layers 712 conductively couple the conductors 804, 806 in different layers 712 with each other. For example, the microvias 808 in the layer 712A extend through the layer 712A to conductively couple the conductor 804 in the layer 712A with the conductor 806 in the layer 712B. Similarly, the microvias 808 in the layer 712B extend through the layer 712B to conductively couple the conductor 806 in the layer 712B with the conductor 804 in the layer 712C, and so on. In the illustrated embodiment, each of the microvias 808 conductively couples conductors 804, 806 disposed on or in different and adjacent layers 712. Alternatively, the microvias 808 may extend through more than one layer 712 to conductively couple conductors 804, 806 in different, non-adjacent layers 712, or layers 712 that are separated from each other by one or more other layers 712.
[00141] Figure 26 is a schematic view of the inductor device 700 in accordance with one embodiment. The device 700 is shown in Figure 26 with the substrate 702 (shown in Figure 24) removed to make the relative positions of the conductors 804, 806, the microvias 808, and the ferrite body 710 more clear. The conductors 804, 806 and the microvias 808 are conductively coupled with each other to form a multi-layer conductive coil 900 that helically wraps around the ferrite body 710. As shown in Figure 26, each of the conductors 804, 806 forms a portion of a turn 902 of the coil 900 that extends around the ferrite body 710. The term "turn" is meant to encompass a portion of the coil 900 that extends around the outer periphery of the ferrite body 710 a single time, or that subtends an arc or non-planar circle of 360 degrees. In the illustrated embodiment, each conductor 804, 806 subtends an arc of approximately 180 degrees such that the microvias 808 in different layers 712 (shown in Figure 24) are vertically aligned with each other in two sets 904, 906 of microvias 808, with the sets 904, 906 located on opposite sides of the ferrite body 710. Alternatively, the conductors 804, 806 may subtend arcs of smaller or larger angles such that the microvias 808 are not vertically aligned with each other or are vertically aligned with each other in a single set or in multiple sets of microvias 808.
[00142] Returning to the discussion of the device 700 as shown in Figure 24, the device 700 may provide an inductive element to an electronic circuit 712. The device 700 may be conductively coupled with conductive traces 714 and/or vias 716 that provide conductive pathways with the circuit 712. While the traces 714 and vias 716 couple the circuit 712 with opposite ends of the coil 900 (shown in Figure 26) formed by the conductors 804, 806 and the microvias 808, alternatively, the traces 714 and vias 716 couple the circuit
712 with different points or locations along the coil 900. For example, the traces 714 and vias 716 may be conductively coupled with the conductors 804, 806 and/or microvias 808 in layers 712 other than the layers 712 shown in Figure 26. In operation, current from the circuit 712 flows through the coil 900 formed by the conductors 804, 806 and the microvias 808. At least some of the energy of the current is stored as magnetic energy in. the ferrite body 710. The coil 900 may be used to delay and/or reshape currents flowing through the circuit 712, such as by filtering relatively high frequencies from the current.