This application is based on and claims the benefit of priority from Chinese Patent Application No. 201310381398.3 filed Jul. 3, 2013, the disclosure of which is hereby incorporated by reference in its entirety.
The field of the invention relates generally to electromagnetic components such as inductors, and more particularly to miniaturized, surface mount power inductor components for circuit board applications.
Power inductors are used in power supply management applications and power management circuitry on circuit boards for powering a host of electronic devices, including but not necessarily limited to hand held electronic devices. Power inductors are designed to induce magnetic fields via current flowing through one or more conductive windings, and store energy via the generation of magnetic fields in magnetic cores associated with the windings. Power inductors also return the stored energy to the associated electrical circuit as the current through the winding and may, for example, provide regulated power from rapidly switching power supplies.
Recent trends to produce increasingly powerful, yet smaller electronic devices have led to numerous challenges to the electronics industry. Electronic devices such as smart phones, personal digital assistant (PDA) devices, entertainment devices, and portable computer devices, to name a few, are now widely owned and operated by a large, and growing, population of users. Such devices include an impressive, and rapidly expanding, array of features allowing such devices to interconnect with a plurality of communication networks, including but not limited to the Internet, as well as other electronic devices. Rapid information exchange using wireless communication platforms is possible using such devices, and such devices have become very convenient and popular to business and personal users alike.
For surface mount component manufacturers for circuit board applications required by such electronic devices, the challenge has been to provide increasingly miniaturized components so as to minimize the area occupied on a circuit board by the component (sometimes referred to as the component “footprint”) and also its height measured in a direction parallel to a plane of the circuit board (sometimes referred to as the component “profile”). By decreasing the footprint and profile, the size of the circuit board assemblies for electronic devices can be reduced and/or the component density on the circuit board(s) can be increased, which allows for reductions in size of the electronic device itself or increased capabilities of a device with comparable size. Miniaturizing electronic components in a cost effective manner has introduced a number of practical challenges to electronic component manufacturers in a highly competitive marketplace. Because of the high volume of components needed for electronic devices in great demand, cost reduction in fabricating components has been of great practical interest to electronic component manufacturers.
In order to meet increasing demand for electronic devices, especially hand held devices, each generation of electronic devices need to be not only smaller, but offer increased functional features and capabilities. As a result, the electronic devices must be increasingly powerful devices. For some types of components, such as magnetic components that provide energy storage and regulation capabilities, meeting increased power demands while continuing to reduce the size of components that are already quite small, has proven challenging.
Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified.
Exemplary embodiments of inventive electromagnetic component assemblies and constructions are described below for higher current and power applications having low profiles that are difficult, if not impossible, to achieve, using conventional techniques. Electromagnetic components and devices such as power inductors components may also be fabricated with reduced cost compared to other known miniaturized power inductor constructions. Manufacturing methodology and steps associated with the devices described are in part apparent and in part specifically described below but are believed to be well within the purview of those in the art without further explanation.
As shown in
The core pieces 104, 106, as seen in
Each magnetic body 120 in each core piece 104, 106 is formed with a generally rectangular configuration including a generally planar top surface 122 and a generally planar opposing surface 124 opposing the top surface. Each surface 122, 124 extends parallel to the x, y plane of
In the example shown, the surface of the longitudinal side wall 132 of each core piece is generally flat and planar, while the surface of the opposing longitudinal side wall 130 is contoured. Moreover, and in the example shown, the bottom surface 124 of each core piece 104, 106 is generally flat, while the top surface 122 is contoured. The contours in the top surface 122 and the longitudinal side wall 130 may abut one another to accommodate the coil winding 108 as explained below.
As seen in
The longitudinal side wall 130, as also shown in
In the example of
As seen in
The coil winding 108 is fabricated from a relatively thin electrically conductive material measured in the H dimension (the z plane of
To assemble the component 100, the core pieces 104, 106 are arranged side-by-side on either side of the coil winding 108. The core pieces 104, 106 and the coil winding 108 are inter-fit such that the vertical leg 152 of the coil winding 108 extends partly in the vertical slot 140 of the core piece 104 and partly in the vertical slot 138 of the core piece 106. Likewise, the vertical leg 156 of the coil winding 108 is extended partly in the vertical slot 138 of the core piece 104 and partly in the vertical slot 140 of the core piece 106. The core pieces 104, 106 are moved or drawn toward one other, with the vertical legs 152, 156 of the coil winding 108 in the slots 138, 140 in each core piece 104, 106 until the longitudinal side walls 130 abut one another as seen in
In the illustrated embodiment, about half of each vertical leg 152, 156 and about half of the main winding section 158 of the coil winding 108 is accommodated in each core piece 104, 106. The main winding section 158 is exposed on the top surfaces 122 of each core piece 104 and 106, the vertical legs 152, 156 are captured in the slots of the core pieces 104, 106, and the surface mount terminal tabs 150, 158 are extended on the bottom surfaces 124 of each core piece 104, 106. In the example shown in the drawings, the length L1 and L2 of each core piece 104, 106 is equal and in combination provide the overall length L of the component 100 as shown in
As can be seen in
The side-by-side arrangement of the core pieces 104, 106 in the component 100 provides considerably smaller components than conventional component arrangements having cores stacked vertically on one another with a coil in between. The side-by-side arrangement of the core pieces 104, 106 in a common plane also facilitates the use of a larger coil winding 150 that can more capably perform in higher power, higher current applications.
Compared to the component 100 described above the larger surface mount terminal tabs 210, 212 provide a large contact area for surface mounting to the circuit board 110. The larger contact area reduces direct current resistance (DCR) of the component 200 in se even further than the component 100. Decreasing DCR beneficially increases the efficiency of the component 200 in operation and allows the component 200 to operate at a lower temperature than comparable devices operating with an increased DCR.
The benefits and advantages of the presently claimed invention are now believed to have been amply illustrated in relation to the exemplary embodiments disclosed.
An electromagnetic component assembly has been disclosed including: a first magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; a second magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; and a preformed coil winding separately provided from each of the first and second cores, the coil winding including a first horizontally extending surface mount terminal tab and a first vertical leg; wherein at least one of the first and second core pieces includes a first vertical slot formed in the longitudinal side wall, the first vertical leg received in the first vertical slot and the first surface mount terminal pad extending on the bottom surfaces of the first and second core pieces. The component may be a power inductor.
Optionally, the first and second core pieces may be arranged side-by-side with the longitudinal side wall of the respective first and second core pieces facing one another. The at least one of the first and second core pieces may include a second vertical slot formed in the longitudinal side wall, and the second vertical slot may be spaced from the first vertical slot. The top surface of the at least one of the first and second core pieces may include an inset depressed surface extending between the first and second vertical slots. The coil winding may further include a main winding section, with the main winding section being received in the inset depressed surface. Each of the top surfaces of the at least one of the first and second core pieces may include an inset depressed surface; a portion of the main winding section may be partly received in the inset depressed surface of the first core piece; and a remaining portion of the main winding section may be partly received in the inset depressed surface of the first core piece. The main winding section may be exposed on the top surface of the first core piece and may be exposed on the top surface of the second core piece.
Also optionally, each of the longitudinal side walls of the first and second core pieces may include a first vertical slot; the first vertical leg may be received partly in the first vertical slot of the first core piece; and the first vertical leg may be received partly in the first vertical slot of the second core piece. The coil winding may further include a second vertical leg and a second surface mount terminal tab. The second surface mount terminal tab may extend in an opposite direction to the first surface mount terminal tab. Each of the first and second core pieces may include a first vertical slot and a second vertical slot formed in the longitudinal side wall; the first and second vertical slots may be spaced from one another; the first vertical leg of the coil winding may be received in the first vertical slot of each of the first and second core pieces; and the second vertical leg of the coil winding may be received in the second vertical slot of each of the first and second core pieces.
Also optionally, at least one of the first and second core pieces include may include an inset surface formed in the longitudinal side wall, and the inset surface may define a physical gap when the first and second core pieces are arranged side-by-side with the longitudinal side wall of the respective first and second core pieces facing one another. Each of the first and second core pieces may further include a lateral side wall extending perpendicular to the longitudinal side wall, with the lateral side walls of the first and second core pieces defining an overall length dimension of the component in combination. The first terminal tab may extend entirely across the length dimension of the component.
A method of manufacturing an electromagnetic component assembly has also been disclosed. The method includes: providing a first magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; providing a second magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; wherein at least one of the first and second core pieces includes a first vertical slot formed in the longitudinal side wall; providing a preformed coil winding separately provided from each of the first and second cores, the coil winding including a first horizontally extending surface mount terminal tab and a first vertical leg; and receiving the first vertical leg in the first vertical slot and extending the first surface mount terminal pad on the bottom surfaces of the first and second core pieces. A component may be formed by the method of claim 16, and the component may be a power inductor.
Optionally, the method may also include arranging the first and second core pieces side-by-side with the longitudinal side wall of the respective first and second core pieces facing one another. The top surface of the at least one of the first and second core pieces includes an inset depressed surface extending between the first and second vertical slots, the coil winding may further include a main winding section, and the method may further include receiving the main winding section in the inset depressed surface. Each of the top surfaces of the at least one of the first and second core pieces may also include an inset depressed surface, and the method may further include: receiving a portion of the main winding section partly in the inset depressed surface of the first core piece, and receiving a remaining portion of the main winding section in the inset depressed surface of the first core piece. The method may include exposing the main winding section on the top surface of the first core piece and on the top surface of the second core piece.
Also optionally, each of the longitudinal side walls of the first and second core pieces may include a first vertical slot, and the method may include: receiving the first vertical leg partly in the first vertical slot of the first core piece, and receiving the first vertical leg partly in the first vertical slot of the second core piece.
The coil winding may include a second vertical leg and a second surface mount terminal tab, wherein the second surface mount terminal tab extends in an opposite direction to the first surface mount terminal tab, wherein the each of the first and second core pieces includes a first vertical slot and a second vertical slot formed in the longitudinal side wall, the first and second vertical slots being spaced from one another, and the method may include: receiving the first vertical leg of the coil winding in the first vertical slot of each of the first and second core pieces, and receiving the second vertical leg of the coil winding in the second vertical slot of each of the first and second core pieces.
At least one of the first and second core pieces may include an inset surface formed in the longitudinal side wall, and the method may include defining a physical gap with the inset surface when the first and second core pieces are arranged side-by-side with the longitudinal side wall of the respective first and second core pieces facing one another.
Each of the first and second core pieces may also include a lateral side wall extending perpendicular to the longitudinal side wall, the lateral side walls of the first and second core pieces defining an overall length dimension of the component in combination, and the method also including extending the first terminal tab entirely across the length dimension of the component.
An electromagnetic component assembly has also been disclosed including: a first magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; a second magnetic core piece having a top surface, a bottom surface opposing the top surface, and a longitudinal side wall interconnecting the top and bottom surfaces; and a preformed coil winding formed separately from each of the first and second cores, the coil winding including a pair of horizontally extending surface mount terminal tabs and, a pair of vertical legs extending upwardly from the pair of surface mount terminal tabs, and a main winding section extending between the pair of vertical legs; wherein each of the first and second core pieces includes a first vertical slot and a second vertical slot formed in the longitudinal side wall thereof; wherein the pair of vertical legs are received in the first vertical slot and the second vertical slot of each of the first and second core pieces; wherein the pair of surface mount terminal pads extend on the bottom surfaces of the first and second core pieces; and wherein the main winding section extends on the top surface of the first and second core pieces.
Optionally, each of the top surfaces of the first and second core pieces may include an inset depressed surface, with the main winding section received in the inset depressed surfaces. At least one of the longitudinal side walls of the first and second core pieces may include an inset surface forming a physical gap when the longitudinal side walls of the first and second core pieces are drawn together. The component may be a power inductor.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
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