Patent Application
20090237193
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of Invention
The present invention relates generally to electronic elements and particularly in one exemplary aspect to an improved design and method of manufacturing miniature electronic components including inductive devices (e.g., inductors, “choke coils,” etc.).
2. Description of Related Technology
Conventional inductive components are electronic devices providing storage capability (i.e., storage of energy in a magnetic field) within an alternating current circuit. Inductors are one well-known type of inductive component, and are formed typically using one or more coils or windings, which may or may not be wrapped around a magnetically permeable core. So-called “dual winding” inductors utilize two windings wrapped around a common core.
Transformers are another type of inductive component that are used to transfer energy from one alternating current (AC) circuit to another by magnetic coupling. Generally, transformers are formed by winding two or more wires around a ferrous core. One wire acts as a primary winding and conductively couples energy to and from a first circuit. Another wire (wound around the core to be magnetically coupled with the first wire) acts as a secondary winding and conductively couples energy to and from a second circuit. AC energy applied to the primary windings causes AC energy in the secondary windings and vice versa. A transformer may be used to transform between voltage magnitudes and current magnitudes, to create a phase shift, and to transform between impedance levels.
Ferrite-cored inductors and transformers are commonly used in modern broadband telecommunications circuits to include ISDN (integrated services digital network) transceivers, DSL (digital subscriber line) modems, and cable modems. These devices provide any number of functions including shielding, control of longitudinal inductance (leakage), and impedance matching and safety isolation between broadband communication devices and the communication lines to which they are connected.
Ferrite-core inductive device technology is driven by the need to provide miniaturization while at the same time meeting performance specifications set by chip-set manufactures and standards bodies such as the ITU-T. For example, in DSL modems, micro-miniature transformers are desired that may allow a DSL signal to pass through while introducing a minimal THD (total harmonic distortion) over the DSL signal bandwidth. As another example, dual-winding inductors may be used in telephone line filters to provide shielding and high longitudinal inductance (high leakage).
A common prior art ferrite-cored inductive device is known as the EP-core device. Other similar well-know devices include inter alia so-called EF, EE, ER, and RM devices.
As shown in
The bobbin 109 includes a terminal array 114 generally with the windings 112 penetrating through the truncated portions 116 of the half-pieces 104, 106, the terminal array 114 being mated to a printed circuit board (PCB) or other assembly. Margin tape (not shown) may also be applied atop the outer portions of the outer winding 112 for additional electrical separation if desired.
For each core shape and size, various differing bobbins are available. The bobbins themselves (in addition to the other elements of the parent device) have many different characteristics; they may provide differing numbers of pins/terminations, different winding options, different final assembly techniques, surface mount versus through-hole mount, etc.
Magnet wire is commonly used to wind transformers and inductive devices (such as inductors and transformers, including the aforementioned EP-type device). Magnet wire is made of copper or other conductive material coated by a thin polymer insulating film or a combination of polymer films such as polyurethane, polyester, polyimide (aka “Kapton™”), and the like. The thickness and the composition of the film coating determine the dielectric strength capability of the wire. Magnet wire in the range of 31 to 42 AWG is most commonly used in microelectronic transformer applications, although other sizes may be used in certain applications.
The prior art EP and similar inductive devices described above have several shortcomings. A major difficulty with EP devices is the complexity of their manufacturing process, which gives rise to a higher cost. The use of a bobbin (also called a “form” or “former”) increases not only the cost, but also size and complexity of the final device, since the bobbin is retained within the device upon completion of the manufacturing process. The bobbin consumes space within the device, which could be used for other functionality, or conversely eliminated to give the final device a smaller size and/or footprint.
In addition, the EP core half pieces themselves are relatively costly to mold and produce. For example, by the time the EP transformer is assembled and tested, its volume production cost is high (currently ranging from approximately $0.50 to-$0.70). It would be desirable to produce a device having performance characteristics at least equivalent to those of an EP transformer, but at a significantly lower cost.
It will also be appreciated that prior art core configurations such as the EP core are inherently inflexible because typically only one style or configuration of device that may be produced from the pre-formed core pieces (i.e., one cannot form a different or compound device from the core pieces) based on their orientation. In some applications involving EP cores, there is a need to minimize coupling between core pieces to meet a filter specification requirement.
Furthermore, multiple inductive devices need to be positioned in a compact, e.g., small restate area, to reduce packaging size to produce a low cost per square inch packaged device. Other applications for inductive devices include high power transmitters, transceivers, integrated circuit input and output matching as well as bias networks, and other radio frequency components for filter, amplifier, and microwave mixer designs.
In addition, conventional core configuration have highly optimized core shapes to obtain the required performance and to reduce an occupied volume, thus, these core configurations may incur high production/manufacturing costs. Furthermore, if there are multiple frequency ranges and/or inductor value requirements, these conventional core configurations may not prove a cost effective alternative and result in an unfavorable return on investment costs. Technical considerations for designing a multi-frequency band module using conventional core configurations may prove tricky because core performance in a first frequency band may significantly affect core performance in a second frequency band. Other technical considerations that prove challenging include a need to maintain power saturation conditions for each magnetic core that is a portion of a single module or a core array.
Bonded wire is a well-established product/process used to produce so-called “air coils.” Air coils are inductors, and are typically used in RFID tags, voice coils, sensors, and the like. The materials and manufacturing equipment for producing bonded wire are commercially available from a variety of sources known to the artisan of ordinary skill.
Bonded wire is essentially an enamel-coated wire having additional coating applied (by either the wire vendor or the device manufacturer) to the outer surfaces of the enamel. During winding, the bonded wire coating may be activated (normally by heat, although other types of processes including radiation flux, chemical agents, and so forth) to cause the coated wires to stick/bond together. This approach provides certain benefits and cost economies in the context of electronic component production.
Accordingly, based on the foregoing, there is a need for an improved electronic device, and a method of manufacturing the device, that is both spatially compact and highly flexible in its implementation and configurations, and which provides sufficient magnetic isolation between individual inductive devices so as to permit, inter alia, the tuning of each device individually.
Ideally, such improved device would also allow for the use of substantially identical core elements, not require use of a bobbin, and would utilize existing and well understood formation and process technologies (such as e.g., bonded wire) in order to simplify the manufacturing process and further reduce cost, while maintaining the desired level of electrical performance.
The foregoing needs are satisfied by the present invention providing improved inductive apparatus and methods for manufacturing the same.
In a first aspect of the invention, an improved inductive assembly is disclosed. In one exemplary embodiment, the assembly comprises multiple core elements arranged in a substantially face-to-face fashion so as to form two discrete and longitudinally arranged inductive devices (e.g., inductors, transformers, choke coils, etc.). Identical core elements are used in this embodiment in order to, inter alia, simplify construction and reduce cost. In one variant, bonded windings are used (i.e., without any bobbin or similar structure) in order to simplify the assembly and reduce cost and size. Portions (i.e., risers) of the core elements are separated by gaps to, among other things, increase magnetic isolation between the individual inductive devices while providing the desired electrical and mechanical performance.
In a second embodiment, the assembly includes an internal wall or riser disposed between the two individual inductive devices to magnetically isolate them from one another.
In a third embodiment, the assembly comprises two asymmetric core elements (e.g., one core element with risers, and a second element comprising merely a plate or substantially planar surface).
In a fourth embodiment, multiple inductive devices are formed within the assembly in both longitudinal and transverse directions; e.g., “row and column” so as to form an array.
In a fifth embodiment, one or more additional core elements are stacked in a face-to-back orientation with one of the two aforementioned core elements (that are face-to-face), and windings included therewith, so as to form yet additional inductive devices within the assembly.
In a second aspect of the invention, an inductive device including a bobbin or header is disclosed. In one embodiment, the header comprises a termination header having a plurality of terminations associated therewith. The core elements and windings are contained at least partly within a plastic or other header assembly that facilitates mating of the device to an external device (e.g., PCB). In one variant, the header is self-leaded; i.e., does not require separate conductive terminals. In another variant, the header contains multiple inductive device assemblies in a linear row or column. In still another variant, a bobbin is used around which at least a portion of the inductive device windings are wound, and which also provides for external termination.
In a third aspect of the invention, a method of manufacturing the above-referenced electronic device is disclosed. In one embodiment, a plurality of core elements is provided. A plurality of winding elements is coupled to the plurality of core elements. Each of the winding elements has been formed into a predetermined shape to comprise a substantially unitary body. The winding elements and the plurality of core elements are assembled so that the winding elements are each at least partly contained within a respective cavity that is provided around the plurality of core elements. In one embodiment, the plurality of core elements are located on a half-core device.
In another embodiment, the method comprises: providing a plurality of core elements; providing a plurality of winding conductors; forming the winding conductors into substantially unitary winding elements, the elements substantially retaining their shape after the forming without a bobbin or support structure; disposing the plurality of winding elements to the plurality of core elements so that the winding elements are each at least partly contained within a respective cavity that is formed around at least a portion of the plurality of core elements; and coupling each of the plurality of core elements to at least one other of the plurality of core elements.
In a fourth aspect of the invention, an improved “direct mount” inductive device is disclosed. In one embodiment, the device comprises a form-less inductive device as previously described, yet which mates directly with the parent assembly (e.g., a PCB substrate), thereby obviating the termination header. In one variant, the windings are terminated to surface-metallized pads formed on the device exterior. In another variant, free ends of windings protrude from the device through an aperture formed in an underlying assembly. The free ends are soldered to conductive pads formed on the PCB substrate.
In a fifth aspect of the invention, a method of operating an inductive device is disclosed. In one embodiment, the device comprises a multi-inductor device, and the method comprises: providing an inductive device comprising a plurality of core elements which form a plurality of gapped opposing surfaces, the gapped opposing surfaces being associated with respective ones of the inductors; generating a first flux through the device including across a first of the gaps, the generated first flux being in a first direction; and generating a second flux through the device including across the first gap, the generated second flux being in a second direction. The first and second fluxes flow in the same direction through the first gap.
In one variant, the method further comprises: generating a third flux through the device including across a second of the gaps, the generated third flux being in the second direction; and generating a fourth flux through the device including across the second gap, the generated fourth flux being in the first direction. The third and fourth fluxes flow in the same direction through the second gap.
In a sixth aspect of the invention, an inductive device having a plurality of inductive elements is disclosed. In one embodiment, the device comprises: a first core element; a second core element; and at least two winding elements. The first and second core elements form at least two gapped risers, respective ones of the at least two winding elements being substantially disposed around the at least two gapped risers.
In one variant, the winding elements each comprise bonded wire windings formed into a substantially unitary body.
In another variant, the device comprises a plurality of flux paths when operated, the plurality of paths including substantially parallel paths of common direction through each of the at least two gapped risers. The core elements may also further form a non-gapped or bridged riser, and the plurality of paths include another path through the non-gapped or bridged riser which is substantially parallel with, but of opposite direction to, the paths of the at least two gapped risers.
In a seventh aspect of the invention, a multi-inductor inductive device is disclosed. In one embodiment, the device comprises: a plurality of core elements, the core elements comprising a plurality of risers, at least a portion of the risers comprising a gap; and a plurality of windings, the windings disposed at least partly around respective ones of the risers. The inductors are substantially electrically isolated from one another, the isolation allowing for individualized determination of saturated output power for each of the plurality of inductors.
The features, objectives, and advantages of the invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein:
a comprises exploded perspective view of a two-device (e.g., inductor) embodiment of the inductive assembly of the invention.
b comprises a side view of the embodiment of
c comprises a side view of a two-device embodiment having an internal wall.
a comprises a perspective view of a two-inductor embodiment of the invention.
b comprises a perspective view of a two-inductor embodiment of the device having with an internal wall, according to the invention.
c comprises a half-core perspective view of a four-inductor embodiment (with an internal wall).
d comprises a half-core perspective view of a three-inductor embodiment of the invention.
a comprises a partially and fully assembled perspective view of another embodiment of the invention utilizing juxtaposed rows of inductive devices.
b comprises a partially and fully assembled perspective view of another embodiment of the invention, wherein an asymmetric core element geometry is utilized.
c comprises a partially and fully assembled perspective view of another embodiment of the invention utilizing heterogeneous “stacked” core elements.
a comprises a perspective view of various bobbin and termination header arrangements useful with the inductive device of the invention.
b comprises a perspective view of an exemplary lead frame mounting arrangement used on the inductive device of the invention.
c comprises a perspective view of an exemplary self-leaded (header-less) termination arrangement used on the inductive device of the invention.
Reference is now made to the drawings wherein like numerals refer to like parts throughout.
As used herein, the term “magnetically permeable material” refers to any number of materials commonly used for forming inductive cores or similar components, including without limitation various formulations made from ferrite.
As used herein, the term “winding” refers to any type of conductor(s), irrespective of shape, cross-section, material, or number of turns, which is/are adapted to carry electrical current.
In one salient aspect, the present invention provides improved multi-core inductive electronic assembly and methods for producing the same. One significant benefit of the present invention is high cost efficiency for a corresponding high level of electrical performance, as well as spatial compactness (i.e., the device may be made smaller in size and/or footprint). This is achieved to some degree by decoupling or substantially isolating the flux paths through different constituent devices that make up the inductive assembly.
In effect, a compact, high performance and low-cost inductor assembly is provided by combining numerous cores and coils together within a single form factor. In one exemplary configuration, the core elements are purposely made identical (i.e., are the same production component, albeit often not perfectly identical), thereby allowing for the purchase of larger lots of core elements (and hence allowing for a lower manufacturing cost). Form-less (i.e., bobbin-less) bonded windings are also used in one embodiment in order to further reduce device complexity, cost, and size.
The individual core elements may advantageously be arranged in any number of different ways including, without limitation (i) in a face-to-face co-linear orientation; (ii) in a face-to-back or stacked collinear orientation; (iii) in an orthogonal orientation; and (iv) combinations of the foregoing. They may also be used for application such as coupled inductors.
It will be recognized that while the following discussion is cast in terms of an exemplary multi-ferrite core device, the invention is equally applicable to other core configurations and even other types of inductive devices. Conceivably, any device having a plurality of winding turns and a magnetically permeable core (or comparable structure) may benefit from the application of the approach of the present invention. Accordingly, the following discussion of the inductive device is merely illustrative of the broader concepts.
a comprises exploded perspective view of a two-inductor embodiment of the invention. Referring to
The core elements are fashioned from a magnetically permeable material such as e.g., a soft ferrite or powdered iron as is well known in the electrical arts. The manufacture and composition of such cores is well understood, and accordingly is not described further herein.
Each of the winding elements 201, 203 may comprise a single winding (single strand, bifilar, or otherwise), or alternatively may comprise multiple windings. Such multiple windings may be in the form a unitary structure (such as where the windings are bonded together, interwoven, or bifilar) or may alternatively comprise two or more substantially discrete winding elements (such as, e.g., two winding “toroids” placed immediately adjacent one another between the two core elements). The windings may also be insulated (such as by using Kapton™ polyimide or another type of insulation), comprise so-called “magnet wire,” or comprise any number of different conductor configurations.
For example, in one variant, the bonded wire comprises 35 AWG-42 AWG bondable wire manufactured by the Bridgeport Insulated Wire Company of Bridgeport, Conn., although other manufacturers, configurations, and sizes of wire may be used. This wire comprises round copper magnet wire with a polyurethane base coating. The polyurethane base coat has a polyamide (Kapton) and self-bonding overcoat. The wire of the illustrated embodiment may be made to comply with relevant electrical standards (e.g., with the NEMA MW29-C and IEC 317-35 international standards for wire), although this is not required in any fashion
In the exemplary embodiment, the first and second winding elements, e.g., 201 and 203, comprise “form-less” windings of the type described in co-pending and co-owned U.S. patent application Ser. No. 10/885,868 filed Jul. 6, 2004, entitled “Form-less Electronic Device and Methods of Manufacturing” incorporated herein by reference in its entirety, although other approaches may be used as well. The form-less windings have the advantage of low cost and lack of a former or bobbin, thereby reducing their spatial profile considerably while maintaining the desired electrical performance.
While bonded wire is preferred, the device 200 may also utilize wound coils formed and coated as described generally in U.S. Pat. No. 6,642,827 to McWilliams, et al. issued Nov. 4, 2003 and entitled “Advanced Electronic Miniature Coil and Method of Manufacturing,” which is incorporated herein by reference in its entirety. Specifically, a Parylene coating is applied to a plurality of individual wires formed into a layer or group using for example a vapor or vacuum deposition process. Parylene is chosen for its superior properties and low cost; however, certain applications may dictate the use of other insulating materials. Such materials may be polymers such as for example fluoropolymers (e.g., Teflon, Tefzel), polyethylenes (e.g., XLPE), polyvinylchlorides (PVCs), or conceivably even elastomers. Additionally, dip or spray-on coatings may be used to form the winding elements 102, 104 of the illustrated invention.
Furthermore, as shown in
It will also be appreciated that while the embodiment of
Specifically, since inductors are DC energy storage devices, they are governed by their inductance and the DC current being applied. Prior art devices using ferrite cores only allow for small amounts of energy to be stored within the component before the ferrite material magnetically saturates. It is noted that ferrite has been developed and applied primarily in AC applications (e.g. transformers). To improve the energy storage capability, an air-gap is introduced into the core shape, typically on the center leg (or around the periphery of a toroid core), where the energy is stored in the form of DC magnetic flux. When the DC magnetic flux becomes sufficiently large, the inductor will again be seen to saturate and cease to have an inductive character. Hence, the ferrite core operates primarily as a path for the flux to enter the air-gap.
Because the ferrite provides a path through the gap, it is possible to form part of the path by using the core of another inductor. Advantageously, the multi-ferrite approach of the present invention takes advantage of this feature, in effect using pairs of core elements, e.g., pieces, as part of the induction path for the inductor(s). At least two separate gaps (for two inductors) are required for this approach, and the gaps of the respective devices must not significantly interact. A first half-core plate 227a and a second half core plate 227b form return paths for the flux of the coil of a first and a second inductive device; therefore, this core configuration provides both an operating environment and separation, e.g., isolation, mechanism (as illustrated by the flux lines depicted in
A significant aspect of the device 200 (in
Referring to
Referring again to
Furthermore, the flux lines of the first inductive device 215 and the second inductive device 216 may be further isolated by the addition of e.g., an internal ungapped bridge or wall 220 (as shown in
The bridge or wall 220 may comprise another (e.g., third) riser on each of the respective core elements 227a, 227b which meets with the other riser to form a gapless union when the device is assembled, similar to those used to form the gapped pathways previously described. It may literally be any shape or cross-section (although a round or circular cross-section is shown in the illustrated embodiment). The thickness 221a and the width 221b of the internal feature 220 may be chosen to meet the desired performance goal(s); e.g., decrease signal cross coupling (e.g., cross talk) between the inductive devices 215, 216. Thus, a high level of magnetic isolation may be maintained between the devices 215, 216 (shown in
Another advantage the internal bridge or wall 220 may include reducing cavity mode resonances, e.g., undesired magnetic flux or current mode resonances, such that may occur within the channel 224 between the devices 215, 216. The thickness 221a and the width 221b of the feature 220 may also be selected to eliminate or decrease undesirable resonant modes so as to enhance or improve performance in a selected frequency range. It will also be appreciated that the diameter of the risers 205, 210 can be adjusted along with the gap (i.e., the surface area of face of each riser) in order to vary the coupling characteristics across each gap. The foregoing dimensions (i.e., gap width, riser area, channel size, wall dimensions, etc.) may be readily optimized by those of ordinary skill for the particular device application and parameters provided the present disclosure (whether manually, by computer simulation, or another approach); accordingly, the particulars of this optimization process are not discussed further herein.
Furthermore, the addition of the internal bridge or wall 220 increases mechanical stability and strength of the device 200 as a whole.
A design advantage of the illustrated topology of
Additionally, because the devices 215, 216 are substantially isolated from one another in terms of magnetic field, an array of inductive devices may advantageously be created, the constituent inductive devices which may be individually tuned (or even turned-off or turned-on), each within a different desired frequency range or selected saturated output power level if desired.
As shown in
It is also noted that the core pieces have no chirality or “handedness” from the standpoint that any of the core pieces may be used in place of the others, and in effectively any orientation. Hence, there is no “up/down” or “left/right” distinction between the core pieces. This greatly simplifies assembly since the core components (and even the winding elements) may be assembled in multiple orientations; i.e., a machine or manual assembler need not look at each piece selected and orient it properly before assembly; there is more than one possible “correct” orientation of the two elements.
The size of the gaps may be controlled readily through machining or forming processes of the type well known in the art. Specifically, in a face-to-face orientation such as that of
The core elements 227a, 227b may optionally include riser spacer elements 228a-d (
Moreover, it will be appreciated that the core elements 227 of the invention may be used with a bobbin-type arrangement, which may or may not include a terminal array (see discussion of
The “adjustable” gap design of the present invention provides a system designer with the capability to tune electrical performance of core elements on an individual and/or on a paired basis. For instance, saturated output power and/or frequency range may be tuned for the inductive devices 215, 216 individually and/or for the assembly as a whole.
It will also be recognized that the core element geometry relative to the diameter of the windings (as wound) may be varied. As shown in
a illustrates another embodiment of the invention, wherein elongated risers 305, 310 are used, and the contact “legs” of the core element(s) 315, 320 are disposed laterally to the risers and planar elements (as opposed to at the ends of the planar elements 211 as shown in
b illustrates yet another embodiment of the invention, wherein elongated risers are used, and the contact “legs” of the core element(s) are disposed laterally to the risers and planar elements, yet the two core elements are effectively juxtaposed (i.e., in a side-by-side orientation). A central dividing wall 350, which is thicker than the two outer walls or legs 345, 355 is also provided to give enhanced separation or isolation of the devices, as well as provide mechanical stability.
The modular or “isolated” approach of the invention also allows for extension of the number of inductors of the device in multiple dimensions; see, e.g., the juxtaposed core element and risers 380, 375 of the device of
As illustrated in
It is further recognized that the inductive assembly of the present invention may take any number of different forms or configurations in terms of its shape, including substantially square, circular, or polygonal form, depending on the needs of the particular application. This is true not only of the outer shape, but also of the core interior surfaces as well. In particular, the multiple core approach may be applied to most core shapes, such as the EP core shape, as shown in
a illustrates an exemplary assembled implementation of the device of
In yet another example,
The technology of the present invention may be used in conjunction with, inter alia, the technology disclosed in U.S. patent application Ser. No. 60/600,985 filed on Aug. 12, 2004 previously incorporated by reference herein; i.e., a stacked approach using multiple core elements in face-to-back orientation.
c illustrates yet another embodiment of the invention, wherein a combination implementation of a face-to-face two core-element arrangement (as shown in 5a), and a single core element in a face-to-back orientation, is used. The single core element is disposed atop the assembled two-element device, and a half-height winding used accordingly. For instance, magnetic and/or material properties for the various core elements and windings 555, 560, 565, 570, and 575 may be individually or collectively chosen to achieve desired performance criteria. Such desired performance criteria may include for example the inductance value, reactance value, real or complex impedance, operating frequency range, and saturated output power level.
In summary, system variables of inductor winding(s) in combination with gap spacing advantageously allow a designer to realize an inductor array that may satisfy multiple filter/electronic component requirements. Magnetic flux paths may be realized utilizing one or more core pieces, e.g., elements, using a multitude of geometries. As such, the embodiments of
It will also be recognized that methods of precisely controlling the electrical and magnetic performance of the inductive devices disclosed herein may be used, including control of the gap thickness and properties, as well as the placement of the gap relative to other components within the device.
The multi-ferrite device disclosed herein (as well as other embodiments) may advantageously be used with most any kind of termination header or structure, or without one as well. For example, a molded plastic header or carrier of the type well known in the art (not shown) adapted to receive at least a portion of the device may be used, such as to form an array or assembly of several individual multi-ferrite modules (each having two or more constituent inductive devices). This header may also be used to house other components besides the modules themselves if desired.
In this example, conductive terminals on or within the header may be used to interface to the pads on a PCB or other external device, as well as to the inductive device windings described above. An exemplary header or termination element includes plurality (e.g., ten connection points on each) of terminals; see e.g., the exemplary configuration of
Additionally, the exact placement of the terminals within the header may be optimized based upon circuit placement and mounting considerations at the device or system level.
Furthermore, it will be appreciated that the header may comprise a self-leaded arrangement (see
As shown in
In another variant, the conductive terminals may be bonded directly to the core elements 205a, 205b, 210a, 210b such as with a compound such as a silicone rubber encapsulant, or electronics epoxy. This approach obviates the cost and space associated with the header.
Similarly, a metallization process can be used to coat or form a layer (e.g., by deposition, electroplating, etc.) on the surface of portions of one or more of the core elements so as to permit “self-leading”. The core elements may even be shaped in this regards so as to facilitate self-leading (for example, by including features that enhance the self-leading metallization and bonding process). See, e.g., co-pending U.S. patent application Ser. No. 11/231,486 filed Sep. 20, 2005 entitled “Simplified Surface-Mount Devices and Methods”, incorporated herein by reference in its entirety, which discloses exemplary self-leading processes and configurations.
Referring to
Core assembly (i.e., mating the core elements/plates together) may be carried out by a multitude of methods. Some of the core assembly methods include e.g., taping using several layers of a suitable tape material (e.g., one rated for sufficient temperature and life), and gluing to form a stacked core by bonding face-face using a suitable epoxy resin/glue to bond two cores together with sufficient strength. Other core assembly methods which may be used consistent with the invention include bridge-bonding using an epoxy/glue between core legs (risers) to reduce air-gap space, and/or over top of the core joints, and core taping with bridge bonding for larger stacked components (e.g., taping the cores together first, and afterwards bridge-bonding over the uncovered areas of the core).
Yet another assembly method may comprise clipping and capping to hold together the cores, which may in some instances require some bridge-bonding or another mechanism to ensure that the clip (such as a simple band, U-clip, etc.) stays in position. The core elements can also be formed or machined with grooves, recesses, etc. to facilitate the aim of maintaining the core elements in the desired orientation.
Yet other approaches for bonding the core elements may be feasible as well, such as laser or ion-beam welding.
The multi-ferrite approach of the invention may also be applied to “low profile” technologies such as, for example, that described in U.S. patent application Ser. No. 10/885,868 filed Jul. 6, 2004, previously incorporated by reference herein. Specifically, the aforementioned protrusion of the winding elements may be made to face the PCB or substrate to which the device 200 is mounted, and cooperating with an aperture or recess formed in that PCB or substrate. The leads of the device 200 may be routed on the same side of the PCB as to which the device is mounted, or alternatively may be routed through the aperture and terminated on the other side of the PCB. To reduce size, a self-bonded wire coil may be utilized; however, the disclosed topology even with the bobbin design may have possible to meet tighter size limitations.
It will be appreciated from the foregoing that benefits of the present invention include, inter alia:
(i) a reduction in overall size of the device as compared to traditional configurations, and a higher density of components (especially when using “bonded” winding approaches such as those previously described);
(ii) the ability to use identical core element(s) for many or all device configurations to reduce cost, labor, and volume dimensionality;
(iii) a degree of self-shielding afforded by the gapped core configuration (with optional internal bridge or wall) so that cross talk between the winding elements is mitigated;
(iv) the stacked approach described herein may be utilized with nearly all standard or non-standard core shapes, and hence is largely independent of or agnostic to core-shape;
(v) the assembly is highly scalable in terms of number of individual constituent devices;
(vi) different core types and component configurations may be mixed together (with proper adaptation to ensure that the various magnetic paths created within the composite device are compatible and the desired electrical performance is maintained); and
(vii) the assembly can be used for many magnetic applications (including for example and without limitation DSL applications, power magnetics, such as for SMPS and the automotive industry, etc.).
It is noted that the benefit in size reduction may be quite significant when the stacking arrangement of the present invention is coupled with the self-bonded winding arrangement of U.S. Ser. No. 10/885,868 filed Jul. 6, 2004, previously incorporated herein. However, even when the stacking arrangement is used with a bobbin or spool-based design, a smaller size none-the-less results as compared to the prior art.
The inductive device of the present invention finds use in any number of different applications where two or more inductors are required (especially those where surface mount footprint and/or overall device volume are limited or critical). One such exemplary application comprises DSL splitters, wherein multiple lightweight and compact yet high-performance inductors are desired.
Furthermore, while the following is cast in terms of the device 200 of
As shown in
The prepared coils are then disposed between the respective core elements, the latter being optionally bonded together with adhesive or epoxy, or other methods as previously described (step 714). The assembled core is then disposed onto the termination header (if used) and optionally bonded thereto using adhesive or another means (step 716), and the free ends of the windings terminated to their respective terminals (step 718). The device is then optionally tested per step 720.
Furthermore, the methods of manufacturing (and process/component control and selection during manufacturing) described in co-pending and co-owned U.S. application Ser. No. 10/000,877 filed, Dec. 14, 2001, entitled “Controlled Induction Device and Method of Manufacturing”, incorporated herein by reference in its entirety, may be used in conjunction with the teachings of the present invention if desired to further control electrical and/or magnetic performance.
It will be recognized that while certain aspects of the invention are described in terms of a specific sequence of steps of a method, these descriptions are only illustrative of the broader methods of the invention, and may be modified as required by the particular application. Certain steps may be rendered unnecessary or optional under certain circumstances. Additionally, certain steps or functionality may be added to the disclosed embodiments, or the order of performance of two or more steps permuted. All such variations are encompassed within the invention disclosed and claimed herein.
While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the invention. The foregoing description is of the best mode presently contemplated of carrying out the invention. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the invention. The scope of the invention should be determined with reference to the claims.
This application is related to the subject matter of co-pending U.S. patent application Ser. No. 11/203,042 filed Aug. 12, 2005 and entitled “Stacked Inductive Device and Methods of Manufacture,” which claims priority to U.S. Provisional Application Ser. No. 60/600,985 filed Aug. 12, 2004, of the same title, both incorporated herein by reference in their entirety. This application is also related to the subject matter of co-pending U.S. patent application Ser. No. 11/213,461 filed Aug. 26, 2005 and entitled “Precision Inductive Devices and Methods”, also incorporated herein by reference in its entirety.
