Abstract:
Methods of manufacturing low profile magnetic components configured as a power management devices for an electrical system of an electronic device involve prefabricated coil windings assembled with a plurality of flexible dielectric sheet layers, and laminating the plurality of flexible dielectric sheets around the prefabricated coil windings to form a dielectric body having a low profile chip configuration attachable to the electronic device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 11/519,349 filed Sep. 12, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to manufacturing of electronic components including magnetic cores, and more specifically to manufacturing of surface mount electronic components having magnetic cores and conductive coil windings. 
     A variety of magnetic components, including but not limited to inductors and transformers, include at least one conductive winding disposed about a magnetic core. Such components may be used as power management devices in electrical systems, including but not limited to electronic devices. Advancements in electronic packaging have enabled a dramatic reduction in size of electronic devices. As such, modern handheld electronic devices are particularly slim, sometimes referred to as having a low profile or thickness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a magnetic component according to the present invention. 
         FIG. 2  is an exploded view of the device shown in  FIG. 1 . 
         FIG. 3  is a partial exploded view of a portion of the device shown in  FIG. 2 . 
         FIG. 4  is another exploded view of a the device shown in  FIG. 1  in a partly assembled condition. 
         FIG. 5  is a method flowchart of a method of manufacturing the component shown in  FIGS. 1-4 . 
         FIG. 6  is a perspective view of another embodiment of a magnetic component according to the present invention. 
         FIG. 7  is an exploded view of the magnetic component shown in  FIG. 6 . 
         FIG. 8  is a schematic view of a portion of the component shown in  FIGS. 6 and 7 . 
         FIG. 9  is a method flowchart of a method of manufacturing the component shown in  FIGS. 6-8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Manufacturing processes for electrical components have been scrutinized as a way to reduce costs in the highly competitive electronics manufacturing business. Reduction of manufacturing costs are particularly desirable when the components being manufactured are low cost, high volume components. In a high volume component, any reduction in manufacturing costs is, of course, significant. Manufacturing costs as used herein refers to material cost and labor costs, and reduction in manufacturing costs is beneficial to consumers and manufacturers alike. It is therefore desirable to provide a magnetic component of increased efficiency and improved manufacturability for circuit board applications without increasing the size of the components and occupying an undue amount of space on a printed circuit board. 
     Miniaturization of magnetic components to meet low profile spacing requirements for new products, including but not limited to hand held electronic devices such as cellular phones, personal digital assistant (PDA) devices, and other devices presents a number of challenges and difficulties. Particularly for devices having stacked circuit boards, which is now common to provide added functionality of such devices, a reduced clearance between the boards to meet the overall low profile requirements for the size of the device has imposed practical constraints that either conventional circuit board components may not satisfy at all, or that have rendered conventional techniques for manufacturing conforming devices undesirably expensive. 
     Such disadvantages in the art are effectively overcome by virtue of the present invention. For a full appreciation of the inventive aspects of exemplary embodiments of the invention described below, the disclosure herein will be segmented into sections, wherein Part I is an introduction to conventional magnetic components and their disadvantages; Part II discloses an exemplary embodiments of a component device according to the present invention and a method of manufacturing the same; and Part III discloses an exemplary embodiments of a modular component device according to the present invention and a method of manufacturing the same. 
     I. INTRODUCTION TO LOW PROFILE MAGNETIC COMPONENTS 
     Conventionally, magnetic components, including but not limited to inductors and transformers, utilize a conductive winding disposed about a magnetic core. In existing components for circuit board applications, magnetic components may be fabricated with fine wire that is helically wound on a low profile magnetic core, sometimes referred to as a drum. For small cores, however, winding the wire about the drum is difficult. In an exemplary installation, a magnetic component having a low profile height of less than 0.65 mm is desired. Challenges of applying wire coils to cores of this size tends to increase manufacturing costs of the component and a lower cost solution is desired. 
     Efforts have been made to fabricate low profile magnetic components, sometimes referred to as chip inductors, using deposited metallization techniques on a high temperature organic dielectric substrate (e.g. FR-4, phenolic or other material) and various etching and formation techniques for forming the coils and the cores on FR4 board, ceramic substrate materials, circuit board materials, phoenlic, and other rigid substrates. Such known techniques for manufacturing such chip inductors, however, involve intricate multi-step manufacturing processes and sophisticated controls. It would be desirable to reduce the complexity of such processes in certain manufacturing steps to accordingly reduce the requisite time and labor associated with such steps. It would further be desirable to eliminate some process steps altogether to reduce manufacturing costs. 
     II. MAGNETIC DEVICES HAVING INTEGRATED COIL LAYERS 
       FIG. 1  is a top plan view of a first illustrative embodiment of an magnetic component or device  100  in which the benefits of the invention are demonstrated. In an exemplary embodiment the device  100  is an inductor, although it is appreciated that the benefits of the invention described below may accrue to other types of devices. While the materials and techniques described below are believed to be particularly advantageous for the manufacture of low profile inductors, it is recognized that the inductor  100  is but one type of electrical component in which the benefits of the invention may be appreciated. Thus, the description set forth below is for illustrative purposes only, and it is contemplated that benefits of the invention accrue to other sizes and types of inductors as well as other passive electronic components, including but not limited to transformers. Therefore, there is no intention to limit practice of the inventive concepts herein solely to the illustrative embodiments described herein and illustrated in the Figures. 
     According to an exemplary embodiment of the invention, the inductor  100  may have a layered construction, described in detail below, that includes a coil layer  102  extending between outer dielectric layers  104 ,  106 . A magnetic core  108  extends above, below and through a center of the coil (not shown in  FIG. 1 ) in the manner explained below. As illustrated in  FIG. 1 , the inductor  100  is generally rectangular in shape, and includes opposing corner cutouts  110 ,  112 . Surface mount terminations  114 ,  116  are formed adjacent the corner cutouts  110 ,  112 , and the terminations  114 ,  116  each include planar termination pads  118 ,  120  and vertical surfaces  122 ,  124  that are metallized, for example, with conductive plating. When the surface mounts pads  118 ,  120  are connected to circuit traces on a circuit board (not shown), the metallized vertical surfaces  122 ,  124  establish a conductive path between the termination pads  118 ,  120  and the coil layer  102 . The surface mount terminations  114 ,  116  are sometimes referred to as castellated contact terminations, although other termination structures such as contact leads (i.e. wire terminations), wrap-around terminations, dipped metallization terminations, plated terminations, solder contacts and other known connection schemes may alternatively be employed in other embodiments of the invention to provide electrical connection to conductors, terminals, contact pads, or circuit terminations of a circuit board (not shown). 
     In an exemplary embodiment, the inductor  100  has a low profile dimension H that is less than 0.65 mm in one example, and more specifically is about 0.15 mm. The low profile dimension H corresponds to a vertical height of the inductor  100  when mounted to the circuit board, measured in a direction perpendicular to the surface of the circuit board. In the plane of the board, the inductor  100  may be approximately square having side edges about 2.5 mm in length in one embodiment. While the inductor  100  is illustrated with a rectangular shape, sometimes referred to as a chip configuration, and also while exemplary dimensions are disclosed, it is understood that other shapes and greater or lesser dimensions may alternatively utilized in alternative embodiments of the invention. 
       FIG. 2  is an exploded view of the inductor  100  wherein the coil layer  102  is shown extending between the upper and lower dielectric layers  104  and  106 . The coil layer  102  includes a coil winding  130  extending on a substantially planar base dielectric layer  132 . The coil winding  130  includes a number of turns to achieve a desired effect, such as, for example, a desired inductance value for a selected end use application of the inductor  100 . The coil winding  130  is arranged in two portions  130 A and  130 B on each respective opposing surface  134  ( FIG. 2) and 135  ( FIG. 3 ) of the base layer  132 . That is, a double sided coil winding  130  including portions  130 A and  130 B extends in the coil layer  102 . Each coil winding portion  130 A and  130 B extends in a plane on the major surfaces  134 ,  135  of the base layer  132 . 
     The coil layer  102  further includes termination pads  140 A and  142 A on the first surface  134  of the base layer  132 , and termination pads  140 B and  142 B on the second surface  135  of the base layer  132 . An end  144  of the coil winding portion  130 B is connected to the termination pad  140 B on the surface  135  ( FIG. 3 ), and an end of the coil winding portion  130 A is connected to the termination pad  142 A on the surface  134  ( FIG. 2 ). The coil winding portions  130 A and  130 B may be interconnected in series by a conductive via  138  ( FIG. 3 ) at the periphery of the opening  136  in the base layer  132 . Thus, when the terminations  114  and  116  are coupled to energized circuitry, a conductive path is established through the coil winding portions  130 A and  130 B between the terminations  114  and  116 . 
     The base layer  132  may be generally rectangular in shape and may be formed with a central core opening  136  extending between the opposing surfaces  134  and  135  of the base layer  132 . The core openings  136  may be formed in a generally circular shape as illustrated, although it is understood that the opening need not be circular in other embodiments. The core opening  136  receives a magnetic material described below to form a magnetic core structure for the coil winding portions  130 A and  130 B. 
     The coil portions  130 A and  130 B extends around the perimeter of the core opening  136  and with each successive turn of the coil winding  130  in each coil winding portion  130 A and  130 B, the conductive path established in the coil layer  102  extends at an increasing radius from the center of the opening  136 . In an exemplary embodiment, the coil winding  130  extends on the base layer  132  for a number of turns in a winding conductive path atop the base layer  132  on the surface  134  in the coil winding portion  130 A, and also extends for a number of turns below the base layer  132  on the surface  135  in the coil winding portion  130 B. The coil winding  130  may extend on each of the opposing major surfaces  134  and  135  of the base layer  132  for a specified number of turns, such as ten turns on each side of the base layer  132  (resulting in twenty total turns for the series connected coil portions  130 A and  130 B). In an illustrative embodiment, a twenty turn coil winding  130  produces an inductance value of about 4 to 5 μH, rendering the inductor  100  well suited as a power inductor for low power applications. The coil winding  130  may alternatively be fabricated with any number of turns to customize the coil for a particular application or end use. 
     As those in the art will appreciate, an inductance value of the inductor  100  depends primarily upon a number of turns of wire in the coil winding  130 , the material used to fabricate the coil winding  130 , and the manner in which the coil turns are distributed on the base layer  132  (i.e., the cross sectional area of the turns in the coil winding portions  130 A and  130 B). As such, inductance ratings of the inductor  100  may be varied considerably for different applications by varying the number of coil turns, the arrangement of the turns, and the cross sectional area of the coil turns. Thus, while ten turns in the coil winding portions  130 A and  130 B are illustrated, more or less turns may be utilized to produce inductors having inductance values of greater or less than 4 to 5 μH as desired. Additionally, while a double sided coil is illustrated, it is understood that a single sided coil that extends on only one of the base layer surfaces  134  or  135  may likewise be utilized in an alternative embodiment. 
     The coil winding  130  may be, for example, an electro-formed metal foil which is fabricated and formed independently from the upper and lower dielectric layers  104  and  106 . Specifically, in an illustrative embodiment, the coil portions  130 A and  130 B extending on each of the major surfaces  134 ,  135  of the base layer  132  may be fabricated according to a known additive process, such as an electro-forming process wherein the desired shape and number of turns of the coil winding  130  is plated up, and a negative image is cast on a photo-resist coated base layer  132 . A thin layer of metal, such as copper, nickel, zinc, tin, aluminum, silver, alloys thereof (e.g., copper/tin, silver/tin, and copper/silver alloys) may be subsequently plated onto the negative image cast on the base layer  132  to simultaneously form both coil portions  130 A and  130 B. Various metallic materials, conductive compositions, and alloys may be used to form the coil winding  130  in various embodiments of the invention. 
     Separate and independent formation of the coil winding  130  from the dielectric layers  104  and  106  is advantageous in comparison to known constructions of chip inductors, for example, that utilize metal deposition techniques on inorganic substrates and subsequently remove or subtract the deposited metal via etching processes and the like to form a coil structure. For example, separate and independent formation of the coil winding  130  permits greater accuracy in the control and position of the coil winding  130  with respect to the dielectric layers  104 ,  106  when the inductor  100  is constructed. In comparison to etching processes of known such devices, independent formation of the coil winding  130  also permits greater control over the shape of the conductive path of the coil. While etching tends to produce oblique or sloped side edges of the conductive path once formed, substantially perpendicular side edges are possible with electroforming processes, therefore providing a more repeatable performance in the operating characteristics of the inductor  100 . Still further, multiple metals or metal alloys may be used in the separate and independent formation process, also to vary performance characteristics of the device. 
     While electroforming of the coil winding  130  in a manner separate and distinct from the dielectric layers  104  and  106  is believed to be advantageous, it is understood that the coil winding  130  may be alternatively formed by other methods while still obtaining some of the advantages of the present invention. For example, the coil winding  130  may be an electro deposited metal foil applied to the base layer  132  according to known techniques. Other additive techniques such as screen printing and deposition techniques may also be utilized, and subtractive techniques such as chemical etching, plasma etching, laser trimming and the like as known in the art may be utilized to shape the coils. 
     The upper and lower dielectric layers  104 ,  106  overlie and underlie, respectively, the coil layer  102 . That is, the coil layer  102  extends between and is intimate contact with the upper and lower dielectric layers  104 ,  106 . In an exemplary embodiment, the upper and lower dielectric layers  104  and  106  sandwich the coil layer  102 , and each of the upper and lower dielectric layers  104  and  106  include a central core opening  150 ,  152  formed therethrough. The core openings  150 ,  152  may be formed in generally circular shapes as illustrated, although it is understood that the openings need not be circular in other embodiments. 
     The openings  150 ,  152  in the respective first and second dielectric layers  104  and  106  expose the coil portions  130 A and  130 B and respectively define a receptacle above and below the double side coil layer  102  where the coil portions  130 A and  130 B extend for the introduction of a magnetic material to form the magnetic core  108 . That is, the openings  150 ,  152  provide a confined location for portions  108 A and  108 B of the magnetic core. 
       FIG. 4  illustrates the coil layer  102  and the dielectric layers  104  and  106  in a stacked relation. The layers  102 ,  104 ,  106  may be secured to one another in a known manner, such as with a lamination process. As shown in  FIG. 4 , the coil winding  130  is exposed within the core openings  150  and  152  ( FIG. 2 ), and the core pieces  108 A and  108 B may be applied to the openings  150 ,  152  and the opening  136  in the coil layer  102 . 
     In an exemplary embodiment, the core portions  108 A and  108 B are applied as a powder or slurry material to fill the openings  150  and  152  in the upper and lower dielectric layers  104  and  106 , and also the core opening  136  ( FIGS. 2 and 3 ) in the coil layer  102 . When the core openings  136 ,  150  and  152  are filled, the magnetic material surrounds or encases the coil portions  130 A and  130 B. When cured, core portions  108 A and  108 B form a monolithic core piece and the coil portions  130 A and  130 B are embedded in the core  108 , and the core pieces  108 A and  108 B are flush mounted with the upper and lower dielectric layers  104  and  106 . That is, the core pieces  108 A and  108 B have a combined height extending through the openings that is approximately the sum of the thicknesses of the layers  104 ,  106  and  132 . In other words, the core pieces  108 A and  108 B also satisfy the low profile dimension H ( FIG. 1 ). The core  108  may be fabricated from a known magnetic permeable material, such as a ferrite or iron powder in one embodiment, although other materials having magnetic permeability may likewise be employed. 
     In an illustrative embodiment, the first and second dielectric layers  104  and  106 , and the base layer  132  of the coil layer  102  are each fabricated from polymer based dielectric films. The upper and lower insulating layers  104  and  106  may include an adhesive film to secure the layers to one another and to the coil layer  102 . Polymer based dielectric films are advantageous for their heat flow characteristics in the layered construction. Heat flow within the inductor  100  is proportional to the thermal conductivity of the materials used, and heat flow may result in power losses in the inductor  100 . Thermal conductivity of some exemplary known materials are set forth in the following Table, and it may be seen that by reducing the conductivity of the insulating layers employed, heat flow within the inductor  100  may be considerably reduced. Of particular note is the significantly lower thermal conductivity of polyimide, which may be employed in illustrative embodiments of the invention as insulating material in the layers  104 ,  106  and  132 . 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Substrate Thermal Conductivity&#39;s (W/mK) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Alumina (Al 2 O 3 ) 
                 19 
               
               
                   
                 Forsterite (2MgO—SiO 2 ) 
                 7 
               
               
                   
                 Cordierite (2MgO—2Al 2 O 3 —5SiO 2 ) 
                 1.3 
               
               
                   
                 Steatite (2MgO—SiO 2 ) 
                 3 
               
               
                   
                 Polyimide 
                 0.12 
               
               
                   
                 FR-4 Epoxy Resin/Fiberglass Laminate 
                 0.293 
               
               
                   
                   
               
             
          
         
       
     
     One such polyimide film that is suitable for the layers  104 ,  106  and  132  is commercially available and sold under the trademark KAPTON® from E. I. du Pont de Nemours and Company of Wilmington, Del. It is appreciated, however, that in alternative embodiments, other suitable electrical insulation materials (polyimide and non-polyimide) such as CIRLEX® adhesiveless polyimide lamination materials, UPILEX® polyimide materials commercially available from Ube Industries, Pyrolux, polyethylene naphthalendicarboxylate (sometimes referred to as PEN), Zyvrex liquid crystal polymer material commercially available from Rogers Corporation, and the like may be employed in lieu of KAPTON®. It is also recognized that adhesiveless materials may be employed in the first and second dielectric layers  104  and  106 . Pre-metallized polyimide films and polymer-based films are also available that include, for example, copper foils and films and the like, that may be shaped to form specific circuitry, such as the winding portions and the termination pads, for example, of the coil layers, via a known etching process, for example. 
     Polymer based films also provide for manufacturing advantages in that they are available in very small thicknesses, on the order of microns, and by stacking the layers a very low profile inductor  100  may result. The layers  104 ,  106  and  132  may be adhesively laminated together in a straightforward manner, and adhesiveless lamination techniques may alternatively be employed. 
     The construction of the inductor also lends itself to subassemblies that may be separately provided and assembled to one another according the following method  200  illustrated in  FIG. 5 . 
     The coil windings  130  may be formed  202  in bulk on a larger piece or sheet of a dielectric base layer  132  to form  202  the coil layers  102  on a larger sheet of dielectric material. The windings  130  may be formed in any manner described above, or via other techniques known in the art. The core openings  136  may be formed in the coil layers  102  before or after forming of the coil windings  130 . The coil windings  130  may be double sided or single sided as desired, and may be formed with additive electro-formation techniques or subtractive techniques for defining a metallized surface. The coil winding portions  130 A and  130 B, together with the termination pads  140 ,  142  and any interconnections  138  ( FIG. 3 ) are provided on the base layer  132  to form  202  the coil layers  102  in an exemplary embodiment. 
     The dielectric layers  104  and  106  may likewise be formed  204  from larger pieces or sheets of dielectric material, respectively. The core openings  150 ,  152  in the dielectric layers may be formed in any known manner, including but not limited to punching techniques, and in an exemplary embodiment, the core openings  150 ,  152  are formed prior to assembly of the layers  104  and  106  on the coil layer. 
     The sheets including the coil layers  102  from step  202  and the sheets including the dielectric layers  104 ,  106  formed in step  204  may then be stacked  206  and laminated  208  to form an assembly as shown in  FIG. 4 . After stacking  206  and/or laminating  208  the sheets forming the respective coil layers  102  and dielectric layers  104  and  106 , the magnetic core material may be applied  210  in the pre-formed core openings  136 ,  150  and  152  in the respective layers to form the cores. After curing the magnetic material, the layered sheets may be cut, diced, or otherwise singulated  212  into individual magnetic components  100 . Vertical surfaces  122 ,  124  of the terminations  114 ,  116  ( FIG. 1 ) may be metallized  211  via, for example, a plating process, to interconnect the termination pads  140 ,  142  of the coil layers  102  ( FIGS. 2 and 3 ) to the termination pads  118 ,  120  ( FIG. 1 ) of the dielectric layer  104 . 
     With the above-described layered construction and methodology, magnetic components such as inductors may be provided quickly and efficiently, while still retaining a high degree of control and reliability over the finished product. By pre-forming the coil layers and the dielectric layers, greater accuracy in the formation of the coils and quicker assembly results in comparison to known methods of manufacture. By forming the core over the coils in the core openings once the layers are assembled, separately provided core structures, and manufacturing time and expense, is avoided. By embedding the coils into the core, separately applying a winding to the surface of the core in conventional component constructions is also avoided. Low profile inductor components may therefore be manufactured at lower cost and with less difficulty than known methods for manufacturing magnetic devices. 
     It is contemplated that greater or fewer layers may be fabricated and assembled into the component  100  without departing from the basic methodology described above. Using the above described methodology, magnetic components for inductors and the like may be efficiently formed using low cost, widely available materials in a batch process using relatively inexpensive techniques and processes. Additionally, the methodology provides greater process control in fewer manufacturing steps than conventional component constructions. As such, higher manufacturing yields may be obtained at a lower cost. 
     III. A MODULAR APPROACH 
       FIGS. 6 and 7  illustrate another embodiment of a magnetic component  300  including a plurality of substantially similar coil layers stacked upon one another to form a coil module  301  extending between upper and lower dielectric layers  304  and  306 . More specifically, the coil module  301  may include coil layers  302 A,  302 B,  302 C,  302 D,  302 E,  302 F,  302 G,  302 H,  3021  and  302 J connected in series with one another to define a continuous current path through the coil layers  302  between surface mount terminations  305 ,  307 , which may include any of the termination connecting structures described above. 
     Like the component  100  described above, the upper and lower dielectric layers  304  and  306  include pre-formed openings  310 ,  312  defining receptacles for magnetic core portions  308 A and  308 B in a similar manner as that described above for the component  100 . 
     Each of the coil layers  302 A,  302 B,  302 C,  302 D,  302 E,  302 F,  302 G,  302 H,  302 I and  302 J includes a respective dielectric base layer  314 A,  314 B,  314 C,  314 D,  314 E,  314 F,  314 G,  314 H,  314 I and  314 J and a generally planar coil winding portion  316 A,  316 B,  316 C,  316 D,  316 E,  316 F,  316 G,  316 H,  316 I and  316 J. Each of the coil winding portions  316 A,  316 B,  316 C,  316 D,  316 E,  316 F,  316 G,  316 H,  316 I and  316 J includes a number of turns, such as two in the illustrated embodiment, although greater and lesser numbers of turns may be utilized in another embodiment. Each of the coil winding portions  316  may be single-sided in one embodiment. That is, unlike the coil layer  102  described above, the coil layers  302  may include coil winding portions  316  extending on only one of the major surfaces of the base layers  314 , and the coil winding portions  316  in adjacent coil layers  302  may be electrically isolated from one another by the dielectric base layers  314 . In another embodiment, double sided coil windings may be utilized, provided that the coil portions are properly isolated from one another when stacked to avoid electrical shorting issues. 
     Additionally, each of the coil layers  302  includes termination openings  318  that may be selectively filled with a conductive material to interconnect the coil windings  316  of the coil layers  302  in series with one another in the manner explained below. The openings  318  may, for example, be punched, drilled or otherwise formed in the coil layer  402  proximate the outer periphery of the winding  316 . As schematically illustrated in  FIG. 8 , each coil layer  402  includes a number of outer coil termination openings  318 A,  318 B,  318 C,  318 D,  318 E,  318 F,  318 G,  318 H,  318 I,  318 J. In an exemplary embodiment, the number of termination openings  318  is the same as the number of coil layers  302 , although more or less termination openings  318  could be provided with similar effect in an alternative embodiment. 
     Likewise, each coil layer  302  includes a number of inner coil termination openings  320 A,  320 B,  320 C,  320 D,  320 E,  320 F,  320 G,  320 H,  3201 ,  320 J, that likewise may be punched, drilled or otherwise formed in the coil layers  302 . The number of inner termination openings  320  is the same as the number of outer termination openings  318  in an exemplary embodiment, although the relative numbers of inner and outer termination openings  320  and  318  may varied in other embodiments. Each of the outer termination openings  318  is connectable to an outer region of the coil  316  by an associated circuit trace  322 A,  322 B,  322 C,  322 D,  322 E,  322 F,  322 G,  322 H,  3221 , and  322 J. Each of the inner termination openings  320  is also connectable to an inner region of the coil  316  by an associated circuit trace  324 A,  324 B,  324 C,  324 D,  324 E,  324 F,  324 G,  324 H,  324 I, and  324 J. Each coil layer  302  also includes termination pads  326 ,  328  and a central core opening  330 . 
     In an exemplary embodiment, for each of the coil layers  302 , one of the traces  322  associated with one of the outer termination openings  318  is actually present, and one of the traces  324  associated with one of the inner termination openings  322  is actually present, while all of the outer and inner termination openings  318  and  320  are present in each layer. As such, while a plurality of outer and inner termination openings  318 ,  320  are provided in each layer, only a single termination opening  318  for the outer region of the coil winding  316  in each layer  302  and a single termination opening  320  for the inner region of each coil winding  316  is actually utilized by forming the associated traces  322  and  324  for the specific termination openings  318 ,  320  to be utilized. For the other termination openings  318 ,  320  that are not to be utilized, connecting traces are not formed in each coil layer  302 . 
     As illustrated in  FIG. 7 , the coil layers  302  are arranged in pairs wherein the termination points established by one of the termination openings  318  and  320  and associated traces in a pair of coil winding portions  316 A and  316 B, such as in the coil layers  302 A and  302 B, are aligned with one another to form a connection. An adjacent pair of coil layers in the stack, however, such as the coil layers  302 C and  302 D, has termination points for the coil winding portions  316 C and  316 D, established by one of the termination openings  318  and  320  and associated traces in the coil layers of the pair, that are staggered in relation to adjacent pairs in the coil module  301 . That is, in the illustrated embodiment, the termination points for the coil layers  302 C and  302 D are staggered from the termination points of the adjacent pairs  316 A,  316 B and the pair  316 E and  316 F. Staggering of the termination points in the stack prevents electrical shorting of the coil winding portions  316  in adjacent pairs of coil layers  302 , while effectively providing for a series connections of all of the coil winding portions  316  in each coil layer  302 A,  302 B,  302 C,  302 D,  302 E,  302 F,  302 G,  302 H,  302 I and  302 J. 
     When the coil layers  302  are stacked, the inner and outer termination openings  318  and  320  formed in each of the base layers  314  are aligned with another, forming continuous openings throughout the stacked coil layers  302 . Each of the continuous openings may be filled with a conductive material, but because only selected ones of the openings  318  and  320  include a respective conductive trace  322  and  324 , electrical connections are established between the coil winding portions  316  in the coil layers  302  only where the traces  322  and  324  are present, and fail to establish electrical connections where the traces  322  and  324  are not present. 
     In the embodiment illustrated in  FIG. 7 , ten coil layers  302 A,  302 B,  302 C,  302 D,  302 E,  302 F,  302 G,  302 H,  302 I and  302 J are provided, and each respective coil winding portion  316  in the coil layers  302  includes two turns in the illustrated embodiment. Because the coil winding portions  316 A,  316 B,  316 C,  316 D,  316 E,  316 F,  316 G,  316 H,  316 I and  316 J are connected in series, twenty total turns are provided in the stacked coil layers  302 . A twenty turn coil may produce an inductance value of about 4 to 5 μH in one example, rendering the inductor  100  well suited as a power inductor for low power applications. The component  300  may alternatively be fabricated, however, with any number of coil layers  302 , and with any number of turns in each winding portion of the coil layers to customize the coil for a particular application or end use. 
     The upper and lower dielectric layers  304 ,  306 , and the base dielectric layers  314  may be fabricated from polymer based metal foil materials as described above with similar advantages. The coil winding portions  316  may be formed any manner desired, including the techniques described above, also providing similar advantages and effects. The coil layers  302  may be provided in module form, and depending on the number of coil layers  302  used in the stack, inductors of various ratings and characteristics may be provided. Because of the stacked coil layers  302 , the inductor  300  has a greater low profile dimension H (about 0.5 mm in an exemplary embodiment) in comparison to the dimension H of the component  100  (about 0.15 mm in an exemplary embodiment), but is still small enough to satisfy many low profile applications for use on stacked circuit boards and the like. 
     The construction of the component  300  also lends itself to subassemblies that may be separately provided and assembled to one another according the following method  350  illustrated in  FIG. 9 . 
     The coil windings may be formed in bulk on a larger piece of a dielectric base layer to form  352  the coil layers  302  on a larger sheet of dielectric material. The coil windings may be formed in any manner described above or according to other techniques known in the art. The core openings  330  may be formed into the sheet of material before or after forming of the coil windings. The coil windings may be double sided or single sided as desired, and may be formed with additive electro-formation techniques or subtractive techniques on a metallized surface. The coil winding portions  316 , together with the termination traces  322 ,  324  and termination pads  326 ,  328  are provided on the base layer  314  in each of the coil layers  302 . Once the coil layers  302  are formed in step  352 , the coil layers  302  may be stacked  354  and laminated  356  to form coil layer modules. The termination openings  318 ,  320  may be provided before or after the coil layers  302  are stacked and laminated. After they are laminated  356 , the termination openings  318 ,  320  of the layers may be filled  358  to interconnect the coils of the coil layers in series in the manner described above. 
     The dielectric layers  304  and  306  may also be formed  360  from larger pieces or sheets of dielectric material, respectively. The core openings  310 ,  312  in the dielectric layers  304 ,  306  may be formed in any known manner, including but not limited to punching or drilling techniques, and in an exemplary embodiment the core openings  310 ,  312  are formed prior to assembly of the dielectric layers  304  and  306  to the coil layer modules. 
     The outer dielectric layers  304  and  306  may then be stacked and laminated  362  to the coil layer module. Magnetic core material may be applied  364  to the laminated stack to form the magnetic cores. After curing the magnetic material, the stacked sheets may be cut, diced, or otherwise singulated  366  into individual inductor components  300 . Before or after singulation of the components, vertical surfaces of the terminations  305 ,  307  ( FIG. 7 ) may be metallized  365  via, for example, a plating process, to complete the components  300 . 
     With the layered construction and the method  350 , magnetic components such as inductors and the like may be provided quickly and efficiently, while still retaining a high degree of control and reliability over the finished product. By pre-forming the coil layers and the dielectric layers, greater accuracy in the formation of the coils and quicker assembly results in comparison to known methods of manufacture. By forming the core over the coils in the core openings once the layers are assembled, separately provided core structures, and manufacturing time and expense, is avoided. By embedding the coils into the core, a separate application of a winding to the surface of the core is also avoided. Low profile inductor devices may therefore be manufactured at lower cost and with less difficulty than known methods for manufacturing magnetic devices. 
     It is contemplated that greater or fewer layers may be fabricated and assembled into the component  300  without departing from the basic methodology described above. Using the above described methodology, magnetic components may be efficiently formed using low cost, widely available materials in a batch process using relatively inexpensive known techniques and processes. Additionally, the methodology provides greater process control in fewer manufacturing steps than conventional component constructions. As such, higher manufacturing yields may be obtained at a lower cost. 
     For the reasons set forth above, the inductor  300  and method  350  is believed to be avoid manufacturing challenges and difficulties of known constructions and is therefore manufacturable at a lower cost than conventional magnetic components while providing higher production yields of satisfactory devices. 
     IV. CONCLUSION 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.