Abstract:
An embodiment of a circuit includes a circuit module and an inductor disposed over and electrically coupled to the module. Disposing the inductor over the module may reduce the area occupied by the circuit as compared to a circuit where the inductor is disposed adjacent to the module, or to a circuit where the inductor is disposed in the module adjacent to other components of the module. Furthermore, disposing the inductor outside of the module may allow one to install or replace the inductor.

Description:
CLAIM OF PRIORITY 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/267,117 filed on Dec. 7, 2009; which application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     An embodiment of provides a combination design of packaging and assembly that improves upon the conventional art by providing a better form factor, flexibility in selection of the inductor by the user, and a better heat dissipation mechanism for the heat generated by the inductor. 
     SUMMARY 
     An embodiment of a circuit includes a circuit module and an inductor disposed over and electrically coupled to the module. For example, the circuit module may be a power-supply module, and the power-supply module and inductor may together form part or all of a power supply. Disposing the inductor over the module may reduce the area occupied by the circuit as compared to a circuit where the inductor is disposed adjacent to the module, or as compared to a circuit where the inductor is disposed in the module adjacent to other components of the module. Furthermore, disposing the inductor outside of the module may allow one to install or replace the inductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a package for a power supply module; 
         FIG. 2  illustrates an embodiment of a stacked inductor-package assembly; 
         FIG. 3  illustrates an embodiment of a computer system in which an embodiment of a stacked inductor-package assembly may be implemented; 
         FIG. 4  illustrates an embodiment of a technique for stacking an inductor with a package; 
         FIG. 5  illustrates another embodiment of a technique for stacking an inductor with a package; 
         FIG. 6  illustrates an embodiment of a technique for fabricating a stacked inductor-package assembly; 
         FIG. 7  illustrates another embodiment of a technique for fabricating a stacked inductor-package assembly; and 
         FIG. 8  illustrates a flow diagram of an embodiment of a technique for fabricating one or more stacked inductor-package assemblies. 
     
    
    
     DETAILED DESCRIPTION 
     One or more embodiments are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the one or more embodiments. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments. 
       FIG. 1  illustrates an embodiment of a power-supply module  98 , which includes a package  100 , a printed circuit board (PCB)  102 , an integrated circuit chip (IC)  104 , a resistor R, a capacitor C, at least one field effect transistor  106 , electrical contacts or traces that extrude externally from the package and form package leads (or pins)  108 , and the choke, i.e., inductor,  110 . The package body  100  is formed from encapsulating material  112 , which also fills the empty spaces between the components  102 ,  104 ,  106 ,  108 ,  110 , R and C. The inductor  110  is designed to block (i.e., have a high reactance to) a particular frequency in an electrical circuit while passing signals of much lower frequency, e.g., or direct current. That is, the inductor  110  may be used to block alternating current (AC) while passing DC. Furthermore, the encapsulating material  112  may include ceramic, plastic, epoxy or other insulation material. 
       FIG. 2  illustrates an embodiment of a stacked inductor-package assembly  200 . The assembly  200  includes at least one inductor  204  stacked on top of, and external to, a module (e.g., a power-supply module)  206 . The inductor  204  may include a choke inductor, a coupled inductor, or other type of inductor. The inductor  204  is external to the module  206  and is electrically and mechanically coupled to the module  206  by way of the external leads  202  of the module. A potential advantage of an embodiment of the assembly  200  is that it may allow the user/customer of the module  206  to select the type of inductor  204 , and, therefore, may provide for flexible application of the module. 
     For example, a customer may select coupled inductors as the at least one inductor  204 . Coupled inductors include two or more magnetically coupled inductors, for example, as in a transformer, wherein a change in current in one inductor induces a voltage across (and perhaps a current through) another magnetically coupled inductor. 
     In another example, a customer may select one or more uncoupled inductors (e.g., an inductor with a magnetic core or with an air core that is not magnetically coupled to another inductor) as the at least one inductor  204  for controllably and periodically storing and releasing energy. 
     In yet another example, a customer may select one or more choke inductors as the at least one inductor  204 . 
     Thus, an embodiment of the stacked inductor-package assembly  200  of  FIG. 2  may provide an advantage over the module  98  of  FIG. 1 , in which the inductor is selected before it is encapsulated in the package  100 . Another potential advantage of an embodiment of the stacked inductor-package assembly  200  of  FIG. 2  is that because the at least one inductor  204  is stacked on top of the module  206 , and is outside of the module  206 , there may be better dissipation of the heat generated by the inductor  204 . The open area above the inductor  204  allows the heat generated by the inductor to escape; a heat sink may be mounted on top of the inductor to further facilitate cooling of the inductor  204 . Inductors may heat up during operation; in fact, inductors may be one of the largest heat sources in electrical circuits, and if the temperature of an inductor becomes too high, the inductor may malfunction, or cause other components of the circuit to malfunction. Heat sinks or cooling fans may be used to dissipate the heat. But it may be said that an embodiments of the module  206  provides for a natural heat sink by locating the inductor  204  outside the module  206 . 
     Another potential advantage of an embodiment of the module  200  is that the space vacated by the inductor  204  inside the module  206  may be used for implementing additional circuitry and functionality. For example, a multi-phase power-supply-module may be implemented inside the module  206  without increasing the size of the module (relative to the module prior to the removal of the inductor from within the module package). A multi-phase solution provides multiple current output signals (that are combined to produce a single regulated output voltage) differing in their phases, generally by 360°/(# of phases). A multi-phase solution may require additional circuitry compared to a single-phase solution. Or, the assembly  200  may form multiple power supplies that generate multiple regulated output voltages for powering multiple devices. 
     The package  206  may provide mechanical protection and stability for the components  102 ,  104 ,  106 ,  112 ,  202 , R and C, and electrical interconnectivity among the components  102 ,  104 ,  106 ,  112 ,  202 , R and C. The module  206  may be a direct current (DC)-to-DC converter module, which is an electronic circuit that converts a source of DC from one voltage level to another. DC-to-DC converters may be used in portable electronic devices such as cellular phones and laptop computers, which may be supplied with DC power from batteries. The module  206  may also be implemented in a Point of Load (PoL) module, which provides an appropriate supply voltage to a processor, for example, a microprocessor, a digital signal processor (DSP) or an application specific integrated circuit (ASIC). A PoL allows processors and other components with different supply voltages to be mounted on the same motherboard. 
       FIG. 3  illustrates an embodiment of a computer system  300  in which an embodiment of the stacked inductor-electronic package assembly  200  of  FIG. 2  may be implemented. The computer system  300  may include a laptop computer, a desktop computer, or a smart cellular phone such as an iPhone®) or a Blackberry®. The computer system  300  may include a PoL power supply  310  in which the stacked inductor-electronic package assembly  200  may be implemented. The power supply  310  may provide power to one or more of a memory  302 , a microprocessor  304 , a digital signal processor  306 , a graphics processor  308 , and a display  312 . The PoL power supply  310  may provide different input voltages to one or more of the various components  302 ,  304 ,  306 ,  308  and  312 . 
     Referring to  FIG. 4 , the at least one inductor  204  of  FIG. 2  may be attached on top of the module  206  by using one or more embodiments of various manufacturing techniques. In an embodiment, as illustrated in  FIG. 4 , the electronic package leads  402  are bent during the trim and form operation in reverse J-bend formations on top of a package  406  of a module  400  such as a power-supply module. One or multiple leads  402  may be formed on the opposing sides of the top surface of the package  406 . The bent leads  402  provide a solder attach area for the terminals (or solder pads) of the inductor  204 . This technique may be referred to as a surface mounting type technique. 
     In another embodiment as illustrated in  FIG. 5 , at least on inductor  504  is secured to a package  506  of a module  500  by inserting leads (or pins)  532  and  534  of the inductor  504  into the respective VIA holes  544  and  548 . VIA stands for “Vertical Interconnect Access,” which is a vertical electrical connection between different layers of conductors inside the package  506 . A VIA opening begins at the top surface of the package  506  and runs down to the traces inside the package  506 . VIAs may be pads with plated holes that provide electrical connections between copper traces on different layers of the module  500  including, for example, the different layers of a PCB such as the PCB  102  of  FIG. 1 . The VIA holes  544  and  548  may be made conductive by electroplating, or may be filled with annular rings or small rivets (not shown in  FIG. 5 ). The leads  532  and  534  may also be made from conducting material, thereby electrically and physically connecting the inductor  504  with the module  500 . The holes  544  and  548  may be referred to as blind VIAs because they are exposed only on one side (top) of the package  506 . The blind holes  544  and  548  may be created in the package body  506  during fabrication by using mold pins. The technique illustrated in  FIG. 5  may be referred to as an insertion type technique. 
     In yet another embodiment of the present invention, the blind holes  544  and  548  are filled with conductive solder paste by using the reflow process. The reflow process refers to heating and melting the solder to cause it to bond with other components. In this technique, the reflow process is used to fill the VIA holes  544  and  548  with solder. In this technique, the inductor includes bonding pads and is surface mounted to the package  506  by way of the solder filled holes  544  and  548 . The reflow process is run again to attach the bonding pads of the inductor to the solder at the top of the holes  544  and  548 . In the above embodiments, techniques such as solder dispensing, screen printing and solder dotting can be used to apply the solder to the leads and the holes. 
     Referring to  FIG. 6 , electronic modules such as power-supply modules may be mass produced in factories, and may be produced in batches.  FIG. 6  illustrates an embodiment of a batch  600  of four modules  606 . The four modules  606  are shown for illustration purposes and a batch  600  may include various numbers of modules. The batch  600  of modules  606  may be fabricated in a die and during fabrication each module  606  is attached to electrical conductor material such as gold or silicon, which extrudes externally from the module  606 . The conductor material  610  may also interconnect the modules  606  of the batch during a portion of the fabrication process. 
     During an embodiment of the trim and form process, the conductor material  610  on all sides of each module  606  is cut (or trimmed) into strips of various dimensions and forms, depending on the requirements of the module. In an embodiment, during the trim and form operation, the conductor material  610  is trimmed into strips on two sides of each module  606  in a manner that allows the strips on the two sides to be bent to form reverse J-bend leads on top of the module  606 . Embodiments of various techniques including sawing, dicing, and laser cutting may be used during the trim and form operation. Following the formation of the strips, the strips may be bent to form the two reverse J contacts on the top of the module  606 . 
     Referring to  FIG. 7 , in an embodiment, a batch of inductors is fabricated to be assembled with a batch of electronic modules such as power-supply modules. A batch  704  of five inductors I 1 -I 5  (each “inductor” may include one or more inductors) may be attached on top of a batch  706  of five electronic modules P 1 -P 5  by using an embodiment the techniques described above in conjunction with  FIGS. 4-5 . The inductors I 1 -I 5  and the modules P 1 -P 5  may be made at different facilities by different manufacturers. Because the inductors I 1 -I 5  may be coupled together during fabrication, the batch  704  may be referred to as a panel; likewise, because the modules P 1 -P 5  may be coupled together during fabrication, the batch  706  may also be referred to as a panel. 
     An embodiment of the technique illustrated in  FIG. 7  may be referred to as a “chocolate bar” assembly technique because the panels  704  and  706  resemble chocolate bars in that they include five interconnected pieces, e.g., identical inductors I 1 -I 5 , and five interconnected pieces, e.g., identical modules P 1 -P 5 , respectively. For ease of manufacturing, the attachments between the inductors I 1 -I 5  and the attachments between the modules P 1 -P 5  may be removed after the inductors I 1 -I 5  are attached to the modules P 1 -P 5 . Individual stacked inductor-package assemblies  200  ( FIG. 2 ) may be made by detaching the inductors I 1 -I 5  from each other and the modules P 1 -P 5  from each other after the inductor panel  704  and the module panel  706  have been assembled together. 
       FIG. 8  illustrates an exemplary high level flow diagram  800  illustrating an embodiment for fabricating stacked inductor-package assemblies such as an embodiment of the stacked inductor-package assembly  200  of  FIG. 2 . 
     At a step  802 , a module designer determines if the module space vacated by the inductor of, e.g.,  FIG. 1  may be used for adding circuitry/functionality to the module, or if it is better to reduce the size of the module. The module designer then designs the module by determining the structure, function, and application for the module. 
     At step  804 , the module designer determines the various types of inductors that may be suitable for the module. 
     At step  806 , the module designer selects a technique for securing the inductor to the module, such techniques including, e.g., surface mounting ( FIG. 4 ), insertion ( FIG. 5 ), or some other technique. A factor that might affect this determination is the type of inductor the user-customer may prefer to use and the securing means the user-customer may prefer. 
     At step  808 , a module panel including a batch of modules attached to each other is fabricated without including the inductors. 
     At step  810 , an inductor panel including a batch of inductors attached to each other is fabricated. 
     At step  812 , the inductor panel is attached to the top of the module panel. 
     At step  814 , the inductors are detached from each other and the modules are detached from each other to create individual stacked inductor-package assemblies. A potential advantage of an embodiment is that an inductor and a corresponding module may be detachable from each other post-assembly. Therefore, if the inductor or the module fails in the field, it can be replaced with another inductor or module. Thus, the assembly may be repaired and the entire assembly need not be replaced if there is a failure of the inductor or the module, but not of both the inductor and the module. 
     What has been described above includes examples of the disclosed subject matter. It may not be, of course, possible to describe every conceivable combination of components or methodologies for purposes of describing the disclosed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the disclosed subject matter are possible. Accordingly, the embodiments are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the disclosure. 
     In particular and in regard to the various functions performed by the above described components, devices, circuits, systems and the like, the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., a functional equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary aspects of the disclosure. 
     In addition, while a particular feature may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more other features of the other embodiments as may be desired for any given or particular application. Furthermore, to the extent that the terms “includes,” “including,” “has,” “contains,” variants thereof, and other similar words are used in either the detailed description or the claims, these terms are intended to be inclusive in a manner similar to the term “comprising” as an open transition word without precluding any additional or other elements. 
     From the foregoing it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the disclosure. Furthermore, where an alternative is disclosed for a particular embodiment, this alternative may also apply to other embodiments even if not specifically stated.