Patent Publication Number: US-10765002-B2

Title: Electronic module power supply

Description:
BACKGROUND 
     The present invention relates to electronic modules, and more specifically to supplying electrical power to electronic modules. 
     Printed circuit boards provide a structure on which to integrate various electronic components. The integration may be both structural and electrical. That is, a printed circuit board may provide a common base by which to physically couple electronic components and provide a manner in which to electrically couple two or more of them. Physical coupling may, for example, take place through coupling electronic components to the printed circuit board by pin sockets and/or soldering. Electrical coupling between electronic components coupled to a printed circuit board may, for example, take place through conductive traces on or in the printed circuit board. 
     A printed circuit board may also include planes for providing common electrical coupling between components. The commons planes may, for example, be used for power, ground, and signaling. For a printed circuit board having electronic components that operate in different power domains, a number of planes may be included. Other solutions may involve the use of bus bars to provide power for an electronic component. 
     BRIEF SUMMARY 
     In one general implementation, a system for supplying electrical power to an electronic module may include a printed circuit board, an electronic module, and a conductive foil. The printed circuit board may include a number of contact locations on a first side, with at least one of the contact locations electrically coupled to a via to a second side of the printed circuit board. The electronic module may be electrically coupled to the contact locations on the first side of the printed circuit board and receive electrical power through the at least one contact location electrically coupled to a via to a second side of the printed circuit board. The conductive foil may be adapted to convey electrical power for the electronic module and electrically coupled on the second side of the circuit board to at least the via that is electrically coupled to a contact location that receives electrical power for the electronic module. 
     In another general implementation, a system for supplying electrical power to an electronic module may include a conductive foil. The conductive foil may have a first side and a second side and be adapted to convey electrical power for an electronic module. The conductive foil may include electrical coupling locations on the first side that correspond to a first set of printed circuit board vias and passageways from the first side to the second side that correspond to a second set of printed circuit boards vias. 
     The details and features of various implementations will be conveyed by the following description, along with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a drawing illustrating an example system for supplying power to an electronic module. 
         FIG. 2  is another drawing illustrating an example system for supplying power to an electronic module. 
         FIG. 3  is a drawing illustrating an example system for coupling a conductive foil to a printed circuit board. 
         FIG. 4  is a drawing illustrating an example printed circuit board for conveying electrical power from a conductive foil to an electronic module. 
         FIG. 5  is a drawing illustrating an example conductive foil that may be used to convey electrical power for an electronic module. 
         FIG. 6  is a drawing illustrating of an example insulator. 
         FIG. 7  is a flowchart illustrating an example process  700  for forming a power supply for an electronic module. 
     
    
    
     DETAILED DESCRIPTION 
     Electrical power may be supplied to a printed-circuit-board-mounted electronic module through a variety of techniques. In certain implementations, a conductive foil may convey electrical power on the side of a printed circuit board that is opposite the side on which an electronic module is mounted. Thus, electrical power may be delivered to an electronic module without having to add additional power planes to the printed circuit board, which can assist in reducing its thickness and manufacturing complexity. Moreover, the conductive foil may be added after the printed circuit board is manufactured, which may be useful when post-manufacturing design changes are required. 
       FIG. 1  illustrates an example system  100  for supplying power to an electronic module. In general, system  100  includes a printed circuit board  110 , an electronic module  120 , a voltage regulator  130 , and a conductive foil  140 . 
     Printed circuit board  110  may be any appropriate structure for structurally mounting and electrically coupling electronic components, such as resistors, capacitors, inductors, processors, and transceivers. Printed circuit board  110  has two sides  112   a ,  112   b  with dimensions that are typically relatively large compared to the board&#39;s thickness and may be composed of any appropriate material (e.g., fiberglass or FR-4). Printed circuit board  110  typically contains a variety of electrical conduits (e.g., traces, power planes, and ground planes) for electrically coupling electronic components mounted thereto. 
     Electronic module  120  may be any type of powered electronic device. For example, electronic module  120  may be a processor (e.g., a microprocessor, a microcontroller, or an application specific integrated circuit) or a transceiver. Electronic module  120  may be electrically coupled to printed circuit board  110  by any appropriate technique. For example, the electronic module may be coupled to a landing grid array (LGA) or ball grid array (BGA) on the printed circuit board. In the illustrated implementation, electronic module  120  is coupled to an electrical interface  114 . Electrical interface  114  may, for example, be an LGA socket or a BGA socket, with or without a downstop incorporated, into which the electronic module can plug. 
     Voltage regulator  130  is responsible for supplying electrical power for electronic module  120 . In the illustrated example, voltage regulator  130  converts power from printed circuit board  110  to power for electronic module  120 . For instance, the voltage regulator could convert a 5V power on the printed circuit board to a 1V power for the electronic module. Voltage regulator  130  may be electrically coupled to printed circuit board  110  by any appropriate technique. For example, the voltage regulator may be coupled to an LGA or a pin grid array (PGA) on the printed circuit board. In the illustrated implementation, the voltage regulator is coupled to an electrical interface  116 . Electrical interface  116  may, for example, be an LGA or a PGA socket into which the voltage regulator can plug. 
     Conductive foil  140  is responsible for conveying at least some of the electrical power for electronic module  120  from voltage regulator  130 . Conductive foil  140  may, for example, carry a relatively high DC current for electronic module  120 . Conductive foil  140  has a first side  142   a  and a second side  142   b , which typically have dimensions that are substantially larger than the thickness of the conductive foil. Conductive foil  140  may, for example, have a thickness between 60-500 microns, which can vary based on application. Conductive foil  140  may be composed of copper, gold, and/or any other appropriate conductive material. 
     Conductive foil  140  may be electrically coupled to voltage regulator  130  by any appropriate technique. In this illustrated example, conductive foil  140  is directly coupled to voltage regulator  130  by an attachment mechanism (e.g., a screw). In other implementations, the coupling may, for instance, be made by a clamp. 
     Conductive foil  140  is also electrically coupled to printed circuit board  110 . As will be explained in more detail below, conductive foil  140  may, for instance, be electrically coupled to one or more vias in the printed circuit board that convey electricity to one or more contact locations (e.g., grid pads) on first side  112   a  of the printed circuit board. 
     System  100  also includes an insulator  150 , a conformal fill material  160 , a structural support member  170 , and a heat sink  180 . Insulator  150  electrically insulates conductive foil  140  from other components of system  100 , including those used to physically couple the conductive foil to printed circuit board  110 . In certain implementations, insulator  150  should be thin and flexible enough to allow the pressure of conformal fill material  160  to mold the insulator and the conductive foil to the contours of printed circuit board  110  with sufficient force to make effective electrical couplings. Insulator  150  may, for example, be made of rubber, vinyl, or any other appropriate electrically insulating material. 
     Conformal fill material  160  deforms to spread pressure when compressed by structural support member  170 . Conformal fill material  160  may, for example, be made of any appropriate conformable material. For instance, the conformal fill material may be made of expanded Polypropylene (EPP) foam, which is readily deformable. EPP foam can also withstand extremely high temperatures (130 degrees C.) and is highly durable. 
     In certain implementations, conformal fill material  160  may be adhered to insulator  150  or structural support member  170 . Additionally, conductive foil  140  could actually be one manufactured piece that includes the conformal material, the insulator, and the conductive foil laminated together in such away that flexibility is maintained. 
     Structural support member  170  provides a relatively rigid structure for mounting conductive foil  140 , insulator  150 , and conformal fill material  160  to printed circuit board  110 . Structural support member  170  is physically coupled to printed circuit board  110  by mounting posts  190 , which also couple to heat sink  180 . Heat sink  180 , which is mounted to the top of electronic module  120  in this example, provides a way for electronic module  120  to dissipate heat. 
     In the illustrated example, structural support member  170  compresses conductive foil  140 , insulator  150 , and conformal fill material  160  between printed circuit board  110  and the structural support member as the structural support member is mounted to posts  190 , which also couple heat sink  180  to printed circuit board  110 . As the compression occurs, conformal fill material  160  deforms according to irregularities on the surface of second side  112   b  of printed circuit board  110 . The irregularities may, for example, be irregularities in the physical structure of side  112   b  of the printed circuit board and/or irregularities due to components (e.g., traces) installed on side  112   b . The deformation of conformal fill material  160  deforms insulator  150  and conductive foil  140  so that conductive foil  140  may also conform to the irregularities of the printed circuit board surface to make electrical couplings at the appropriate locations of printed circuit board  110 . 
     System  100  additionally includes an insulator  152 . Insulator  152  may be used to insulate other via ends in printed circuit board  110 , which may not be associated with electronic module  120 , from conductive foil  140 . 
     In one mode of operation, voltage regulator  130  receives electrical power from printed circuit board  110 . Printed circuit board  110  may, for instance, contain one or more planes for conveying power to various electronic modules mounted on the printed circuit board, and the voltage regulator may be coupled to one of these power planes. Voltage regulator  130  then converts the electrical power from the printed circuit board to an appropriate electrical power for electronic module  120 . Voltage regulator  130  sends the electrical power through conductive foil  140  to the vias in the printed circuit board that are coupled to contact locations (e.g., grid pads) that receive electrical power for the electronic module, which thus supplies operational power to the electronic module. A return path to the voltage regulator  130  may, for instance, be supplied by a ground plane in the printed circuit board. 
     Since conductive foil  140  may convey the majority of the current from voltage regulator  130  to electronic module  120 , a large inductive loop may be formed. In another mode of operation, voltage regulator  130  may also send a portion of the electrical power through a power plane of printed circuit board  110 , which may be at ground or weaker. Thus, electronic module  120  may receive operational power from the voltage regulator through two paths. The path through conductive foil  140  may have a relatively high inductance and, hence, respond relatively slowly to transients, and the path through the power plane may have a relatively low inductance and, hence, respond relatively quickly to transients. In certain implementations, the conductive foil can convey a DC current and the power plane can convey an AC current. 
     As the electronic module&#39;s power changes, power noise can be generated. Printed circuit board  110  may therefore include a frequency decoupler  118  (e.g., a capacitor) for decoupling the power paths in this mode. The decoupling may, for example, occur at the middle frequencies. 
     System  100  has a variety of features. For example, system  100  may deliver power to an electronic module without having to add additional power planes or ground planes to the printed circuit board, which can assist in reducing its thickness and manufacturing complexity, especially if the electronic module is localized. The delivered power may, for instance, be incompatible with that handled by the printed circuit board&#39;s existing power planes. Moreover, the delivered power may be higher than what a power plane of the printed circuit board can handle, especially when conductive foil  140  can be made relatively thick. As another example, various components of system  100  (e.g., the conductive foil, the insulator, and the conformal fill material) may be added after the printed circuit board is manufactured. Thus, system  100  may be useful when adding an unplanned electronic module to the printed circuit board. 
     In other implementations, a system for supplying power to an electronic module may include fewer, additional, and/or a different arrangement of components. For example, the vias that electrically couple to the conductive foil may not convey electrical power directly through the printed circuit board. For instance, the vias may send some or all of the electrical power through printed circuit board planes to other vias that convey the electrical power to the electronic module or other electronic components. Thus, the electronic module does not have to be directly opposite the conductive foil. As another example, various components of the coupling system, including the structural support member, the insulator, and the conformal fill material may be manufactured with surface contours that complement any systematic irregularities in any of the other elements, which may be the case where the wiring in the printed circuit board has different densities within the electronic module shadow and results in non-planar surfaces on the board. As another example, various components (e.g., the second insulator, the frequency decoupler, and/or the conformal fill) may not be used. Moreover the structural mounting member may be any structure capable of fitting the conductive foil against the printed circuit board. As an additional example, various layers may be added to the conductive foil assembly as needed. 
       FIG. 2  illustrates another example system  200  for supplying power to an electronic module. Similar to system  100 , system  200  includes a printed circuit board  210 , an electronic module  220 , a voltage regulator  230 , and a conductive foil  240 . As can be seen in this example, however, printed circuit board  210  also has a power plane  212 , a signal plane  213 , and a ground plane  214 , which may generally be used for carrying electricity between various components mounted to the printed circuit board. In this example, for instance, signal plane  213  is used for conveying signals between components other than voltage regulator  230  and electronic module  220 . 
     Printed circuit board  210  also includes a number of vias  216 , which are generally used for electrically coupling components on different levels of the printed circuit board. Typically, a region of a circuit board has a large number of vias, but only two have been shown here for each region to clarify the description. For example, via  216   d  couples voltage regulator  230  to power plane  212 , which is coupled to electronic module  220 . Thus, voltage regulator  230  can deliver power to electronic module  220  through power plane  212 . Additionally, via  216   a  couples electronic module  220  to ground plane  214 , which is coupled to voltage regulator  230 . Thus, a return is provided between electronic module  220  and voltage regulator  230 . Conductive foil  240  is coupled to contact location  218  of via  216   b  to also supply electrical power to electronic module  220 . The return path for conductive foil may be provided by ground plane  214 . 
     Although  FIG. 2  illustrates one example of a system for supplying power to an electronic module, other power supply systems may include fewer, additional, and/or a different arrangement of elements. For example, a printed circuit board may contain a variety of electronic components coupled thereto. Moreover, the printed circuit board may include multiple power planes, signal planes, and ground planes, which may be used for electrically coupling various components on the printed circuit board. Additionally, conductive foil  240  may have a system for coupling it to printed circuit board  210 . 
       FIG. 3  illustrates an example system  300  for coupling a conductive foil  320  to a printed circuit board  310 . In this example, printed circuit board  310  includes a number of vias  314  from first side  312   a  of printed circuit board to second side  312   b . Vias  314  convey electrical power from contact locations  316  (e.g., pads) on second side  312   b  to contact locations  316  (e.g., pads) on first side  312   a  of printed circuit board  310 . Note that the printed circuit board may also have additional vias that convey electrical signals to other contact location between first side  312   a  and second side  312   b.    
     Conductive foil  320  includes dendrite groups  322  associated with each contact location  316 . Dendrites are basically small protuberances from the conductive foil that aid in making contact with the contact locations. For example, a dendrite may assist with piercing debris and oxides and/or provide wipe, which is a relative mechanical movement between mating contacts during assembly that aids in digging through oxide layers and pushing debris out of the way, as the system is mated. In certain implementations, the conductive foil may also be plated with gold or other metallurgy at the contact locations with dendrites in order to improve the interconnection. 
     System  300  also includes an insulator  330 , a conformal fill material  340 , and a structural support member  350 , which can used to ensure proper contact between conductive foil  320  and contact locations  316 . As can be seen, second side  312   b  of printed circuit board  310  has irregularities in its surface, which have been exaggerated in this example to illustrate the actual operation. But as structural support member  350  compresses conformal fill material  340 , the material deforms according to the shape of second side  312   b , especially if insulator  330  and conductive foil  320  are readily deformable. And this deformation causes conductive foil  320  to deform to a shape that corresponds to second side  312   b , which assists in making contact between dendrite groups  322  and contact locations  316 . 
       FIG. 4  illustrates an example printed circuit board  400  for conveying electrical power from a conductive foil to an electronic module. In particular,  FIG. 4  illustrates a second side  412   b  of printed circuit board  400 , where a first side of the printed circuit board has one or more electronic modules coupled thereto. 
     Printed circuit board  400  includes a set of contact locations  420  on second side  412   b , which are coupled to vias. Set  420  includes contact locations  422 , which are electrically coupled to vias that are electrically coupled to power receiving contact locations located on the first side of the printed circuit board. Thus, electrical power may flow through contact locations  422  from a conductive foil. Set  420  also includes contact locations  424 , which may be electrically coupled to contact locations at various locations on the printed circuit board. Contact locations  422 ,  424  may, for example, pad areas. If contact locations  422 ,  424  are pads areas, contact locations  422  may encompass the vias associated with the power domain, and contact locations  424  may be small pads. Between contact locations  422  is a conductive fill material  430 , which can serve to distribute electrical power between contact locations  422 . As can be seen, however, a clearance is provided between fill material  430  and contact locations  424 . Contact locations  422  may be plated with gold or other metallurgy to improve the interconnection with the conductive foil. 
     Printed circuit board  400  also includes alignment holes  440  and mounting holes  450 . Alignment holes  440  can assist in positioning a conductive foil, along with its coupling element(s). In certain implementations, for example, the position of a conductive foil may need to be tightly controlled so that is only makes contact with the appropriate contact locations in set  420 . Alignment holes  440  may, for instance, have posts inserted therein to facilitate alignment of the conductive foil, an insulator, and/or a conformal fill material. Such posts may be in contact with the conductive foil and may be non-conductive (e.g., formed from plastic or floating metal) or ohmically attached to the power domain, with a relatively high resistance, for instance. 
     Mounting holes  450  may be used for structurally mounting one or more components (e.g., a heat sink or an electronic module) to the printed circuit board. For example, mounting posts for a heat sink located on the first side of printed circuit board  410  could extend through mounting holes  450  and be secured on the second side of the printed circuit board. Additionally, a conductive foil may be secured to the printed circuit board by the mounting holes. 
     Printed circuit board  400  also includes via ends  460  for other electronic modules coupled to the first side of the circuit board. In particular implementations, these via ends may be covered by an insulator to prevent a conductive foil supplying power through contact locations  422  from coming into contact with these ends. 
     Other implementations may include fewer, additional, and/or a different arrangement of elements. For example, certain implementations may not include alignment apertures. As another example, the contact locations not associated with the electronic module power domain may have a modified padstack in the allegro design that has an enhanced solder mask over the contact locations. This could be used instead of clearances or in conjunction with clearances to help assure that no shorting occurs. As a further example, some or all of the vias not associated with the power domain for the electronic module may not extend completely through the printed circuit board. These vias could, for instance, be coupled to internal planes with signals going to other vias and eventually to other electronic components. As an additional example, the conductive foil may make contact with the conductive fill material at locations other than the contact locations to provide more electrical contact area between the two. 
       FIG. 5  illustrates an example conductive foil  500  that may be used to convey electrical power for an electronic module. Conductive foil  500  includes a number of locations  510  at which electrical coupling may be made with vias of a printed circuit board that convey electrical power to an electronic module on the opposite side of the printed circuit board. Electrical coupling may, for example, be made to pads of the vias. Locations  510  may specially coated (e.g., with gold) and include structure (e.g., dendrites) to assist with making an electrical coupling with the vias. Conductive foil  500  also includes a number of apertures  520  that provide clearance around the printed circuit board vias, and any associated contact locations, that have signals, ground, and/or power other than for the power domain for the electronic module receiving power through the vias of the printed circuit board. 
     Conductive foil  500  additionally includes alignment apertures  530  and mounting apertures  540 . Alignment apertures  530  assist with ensuring proper positioning of conductive foil  500  with respect to the printed circuit board to which it will be mounted, which can prevent shorts between the foil and ground, signal, and other power domains. Mounting apertures  540  are large enough to allow clearance around any mounting posts (e.g., for a structural support member) to ensure that no ohmic connection is made. 
       FIG. 6  illustrates an example insulator  600 . Insulator  600  includes alignment apertures  610  and mounting apertures  620 . Alignment apertures  610  assist with ensuring proper positioning of insulator  600  with respect to the printed circuit board to which it will be mounted. Mounting apertures  620  are large enough to allow clearance around mounting posts (e.g., for a structural support member). Note that a conformal fill material may be patterned similar to the insulator. 
       FIG. 7  illustrates an example process  700  for forming a power supply for an electronic module. Process  700  may, for example, be used to make system  100 . 
     Process  700  calls for positioning a first side of a conductive foil next to a printed circuit board such that an electrical coupling is made with vias that are electrically coupled to power receiving contact locations on an opposite side of circuit board (operation  704 ). The positioning may, for example, be facilitated by aligning apertures in the conductive foil with alignment posts in the printed circuit board. Additionally, the conductive foil may have mounting apertures therein, and these may be aligned with mounting posts that extend from or through the printed circuit board to aid in the positioning of the conductive foil. 
     Process  700  also calls for positioning a first side of an insulator next to a second side of the conductive foil (operation  708 ). The positioning may, for example, be facilitated by aligning apertures in the insulator with alignment posts in the printed circuit board. Additionally, the insulator may have mounting apertures therein, and these may be aligned with mounting posts that extend from or through the printed circuit board to aid in the positioning of the insulator. 
     Process  700  additionally calls for positioning a first side of a conformal fill material next to a second side of the insulator (operation  712 ). The positioning may, for example, be facilitated by aligning apertures in the conformal fill material with alignment posts in the printed circuit board. Additionally, the conformal fill material may have mounting apertures therein, and these may be aligned with mounting posts that extend from or through the printed circuit board to aid in the positioning of the fill material. 
     Process  700  further calls for positioning a structural support member next to a second side of the conformal fill material (operation  716 ). The positioning may, for example, be facilitated by aligning mounting apertures in the structural support member with mounting posts that extend from or through the printed circuit board. 
     Process  700  also calls for coupling the structural support member to the printed circuit board such that the conformal fill material compresses the conductive foil against the printed circuit board (operation  720 ). The coupling may, for example, be accomplished by coupling the structural support member to mounting posts that extend from or through the printed circuit board. 
     Process  700  further calls for coupling the conductive foil to a voltage regulator (operation  724 ). The voltage regulator may, for example, convert power from the printed circuit board to power for the electronic module. 
     Although process  700  illustrates one example process for forming a power supply for an electronic module, other processes for forming a power supply may include fewer, additional, and or a different arrangement of operations. For example, a process may not include positioning the insulator next to the conductive foil and/or the conformal fill material next to the insulator, as two of more of these may be manufactured together as one piece. Moreover, the insulator and/or the conformal fill material may be positioned relative to the conductive foil before the conductive foil is positioned next to the printed circuit board. Additionally, the coupling to the voltage regulator may be performed at various points in a process. 
     The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting. As used herein, the singular form “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in the this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups therefore. 
     The corresponding structure, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present implementations has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The implementations were chosen and described in order to explain the principles of the disclosure and the practical application and to enable others or ordinary skill in the art to understand the disclosure for various implementations with various modifications as are suited to the particular use contemplated. 
     A number of implementations have been described for supplying power to an electronic module, and several others have been mentioned or suggested. Moreover, those skilled in the art will readily recognize that a variety of additions, deletions, modifications, and substitutions may be made to these implementations while still supplying power to an electronic module. Thus, the scope of the protected subject matter should be judged based on the following claims, which may capture one or more concepts of one or more implementations.