Abstract:
An apparatus including a printed circuit board including a body of a plurality of alternating layers of conductive material and insulating material; and a package including a die disposed within the body of the printed circuit board. A method including forming a printed circuit board including a core and a build-up section including alternating layers of conductive material and insulating material coupled to the core; and coupling a package including a die to the core of the printed circuit board such that at least a portion of a sidewall of the package is embedded in at least a portion of the build-up section. An apparatus including a printed circuit board including a body; a computing device including a package including a microprocessor disposed within the body of the printed circuit board; and a peripheral device that provides input or output to the computing device.

Description:
FIELD 
       [0001]    Printed Circuit Boards. 
       BACKGROUND 
       [0002]    Mobile and handheld products are trending towards thinner form factors. Studies show that consumers are willing to pay for thinner and lighter devices to achieve true mobility. Thus device manufacturers are putting emphasis on engineering resources to satisfy consumers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  shows a cross-sectional side view of an embodiment of a portion of a printed circuit including a package embedded therein. 
           [0004]      FIG. 2  shows a cross-sectional side view of another embodiment of a portion of a printed circuit board including a package embedded therein. 
           [0005]      FIG. 3  shows a cross-sectional side of a portion of a core of a printed circuit board. 
           [0006]      FIG. 4  shows the structure of  FIG. 3  following the formation of contact points, lands or pads on a surface of the core of the printed circuit board and the attachment of a package thereto. 
           [0007]      FIG. 5  shows the structure of  FIG. 4  following the addition of a buildup layer portion on one side of the core and the introduction of buildup layers to form a buildup layer portion on an opposite side of the core. 
           [0008]      FIG. 6  shows the structure of  FIG. 5  following the embedding of the package in the printed circuit board. 
           [0009]      FIG. 7  illustrates a schematic illustration of a computing device. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    One component of a computing device that affects an overall thickness of a device, particularly mobile and handheld products, is the motherboard. Currently, a thickness of mobile handheld devices, including mobile personal computers (PCs) and notebooks, is limited by a total of a motherboard stack over the keyboard due to the physical size of the motherboard. Even where the motherboard is installed at a similar level to a battery and other discreet boards, the size of the motherboard impacts these components, such as impacts the battery size which is a key performance specification. One technique to reduce a thickness or Z height and/or a motherboard size is utilizing a high density interconnect (HDI) printed circuit board process. Generally, the HDI process utilizes build up layers on a multilayer core with laser drilled microvias on each buildup to perform signal connections as opposed to a conventional type  3  printed circuit board that uses plated through holes. The use of the laser drilled microvia process in the HDI process enables higher density routing with smaller dimensioned interconnect vias, hence reducing the total board size as well as z-height. 
         [0011]    A printed circuit board such as a motherboard is used to mechanically support and electrically connect an electronic component such as a microprocessor or application processor.  FIG. 1  shows a cross-sectional side view of a portion of a printed circuit board having an embedded component, in this case a package including a microprocessor (e.g., central processing unit, system on chip), connected to the core of the printed circuit board. Referring to  FIG. 1 , in this embodiment, printed circuit board  110  includes core  120  of an insulative material such as a prepreg material onto which conductive planes (e.g., ground plane, power plane) or tracks or pathways or signal traces are formed. In this embodiment, a top conductive plane or signal line includes an array of conductive pads  160  that may be connected to the conductive plane of signal line or other planes or signal lines through, for example, conductive microvias. Pads  160  are configured for and are aligned to connect to conductive pads or points of package  140 . Package  140  is, for example, a flip-chip package (e.g., ultra thin core flip-chip package) or a Bumpless Build-Up Layer (BBUL) package having, for example, a land grid array defining contact points, lands or pads  165  to connect to conductive pads  160 . The connection of contact points  165  to conductive pads may be through solder connections or, in another embodiment through a conductive paste, such as an anisotropic conductive film (ACF) epoxy adhesive.  FIG. 1  also shows die  150  that is, for example, a microprocessor, connected to package  140  on a side opposite the side in contact with conductive pads  160 . 
         [0012]    As noted above, package  140  is connected to a pad array on core  120  of printed circuit board  110 . Package  140  including die  150  is embedded in circuit board  110  in the sense that since it is coupled to the core at its base and buildup layers of a printed circuit board surround the opposing sides of the package.  FIG. 1  shows buildup layer portion  130 A and buildup layer portion  130 B connected to core  120 . Each of buildup layer portion  130 A and buildup layer portion  130 B includes alternating layers of conductive material and dielectric material. The conductive material forms, for example, planes, signal traces or pathways while the insulating material insulates one conductive layer from another. In the embodiment shown in  FIG. 1 , each of buildup layer portion  130 A and buildup layer portion  130 B includes two build up layers (e.g., two layers of conductive material and insulating material). It is appreciated that in other embodiments, less than or more than two buildup layers may be utilized and the number of layers of conductive material and insulating material need not be the same in each of buildup layer portion  130 A and buildup layer portion  130 B. 
         [0013]    In the embodiment shown in  FIG. 1 , package  140  includes contact points, lands or pads  165  on a bottom side of the package (as viewed) as well as contact points, lands or pads  170  on a topside (device side). Contact points, lands or pads  165  and contact points, lands or pads  170  may be used to connect to printed circuit board  110 . Additionally, contact points, lands or pads  165  and contacts points, lands or pads  170  may be utilized to connect package  140  to a device external to the printed circuit board, such as a memory device (e.g., a dynamic random access memory (DRAM)).  FIG. 1  shows conductive microvias  180  formed, for example, by a laser drill process connecting to contact points of external device  190 A through a contact material such as a solder ball. Similar microvias may be used to connect one or more contact points of device  190 B with package  140 . 
         [0014]    As noted, in the embodiment shown in  FIG. 1 , package  140  and die  150  are embedded in printed circuit board  110  in the sense that at least package  140 , and opposing sides and a bottom of die  150  are surrounded by a material of buildup layer portion  130 A. By embedding package  140  and die  150  in printed circuit board  110 , it can be seen that a z-height of the board and package is reduced as the package and die are no longer connected to contact points on a surface (e.g., a superior surface (as viewed)) of printed circuit board  110 . The z-height is reduced in the sense that the z-height of printed circuit board  110  and package  140  is the z-height of printed circuit board  110  as package  140  is no longer connected to contact points on a superior surface of printed circuit board  110 . Also, in this embodiment, a portion of a topside of die  150  is exposed. In one embodiment, overlying chip  150  on a surface of printed circuit board  110  (top surface as viewed) may be a heat-transfer device  198 , such as heat spreader, or other device. 
         [0015]      FIG. 2  shows another embodiment of a printed circuit board including an embedded package. In this embodiment, printed circuit board  210 , such as an HDI printed circuit board, includes core  220  of an insulating material having one or more planes and/or pathways or signal traces. Overlying a surface of core  220  is an array of contact points lands or pads  260  positioned to connect and connected to an array of contact points, lands or pads  265  of package  240 . Package  240  is, for example, a flip-chip package or a BBUL package having contact points  265  as a land grid array patterned to connect to conductive points  260  through, for example, a solder connection or ACF. 
         [0016]    Referring to  FIG. 2 , package  240  including die  250  is embedded in buildup layers of printed circuit board  210 .  FIG. 2  shows buildup layer portion  230 A and buildup layer portion  230 B connected to core  220  with package  240  including die  250  embedded in buildup layer portion  230 A. Buildup layer portion  230 A and buildup layer portion  230 B are each defined by are alternating layers of conductive material and insulating material. In the embodiment shown in  FIG. 2 , buildup layer portion  230 A and buildup layer portion  230 B each include two conductive layers and two insulating layers. It is appreciated that in other embodiments, less than or more than two conductive layers may be included and the number of conductive and insulating layers may be different for each of buildup layer portion  230 A and buildup layer portion  230 B. 
         [0017]    In the embodiment shown in  FIG. 2 , package  240  includes contact points, lands or pads  265  on a bottom surface thereof (as viewed). Package  240  also includes contact points, lands or pads  270  as a land grid array on a superior or device side surface. As noted, contact points or pads  260  are connected to contact points  260  on core  220  that are connected to signal lines or planes (ground planes, power planes). In this embodiment, contact points or pads  270  on a superior surface of package  240  may be connected to signal traces or planes associated with buildup layer portion  230 A and/or to an external device.  FIG. 2  shows external device  290  that is, for example, a memory device (e.g., a DRAM device) connected to contact points  270  thorough conductive microvias  280  in buildup layer portion  230 A. 
         [0018]    In the embodiment shown in  FIG. 2 , package  240  including die  250  is embedded in buildup layer portion  230 A. In this embodiment, the buildup layers surround sides and a top or superior surface each of package  240  and die  250  so that the package and die are completely embedded within printed circuit board  210 . By completely embedding package  240  and die  250  within the circuit board  210 , it can be seen that the z-height of the printed circuit board and package is reduced to that of the z-height of the printed circuit board as the package and die are no longer connected to contact points on a surface of the printed circuit board but the package is embedded in the printed circuit board. 
         [0019]      FIGS. 3-6  describe a process of forming a printed circuit board with an embedded package. In this embodiment, the process relates to forming a printed circuit board/embedded package similar to structure  200  shown in  FIG. 2 . Referring to  FIG. 3 ,  FIG. 3  shows printed circuit board core  310  that is, for example, a core formed according to an printed circuit board process. Core  310  is, for example, a multilayer core including dielectric layer  315  of, for example, a prepreg material onto which conductive and insulative layers are introduced, such as by a film process wherein a film or sheet of insulative material and conductive material are alternately laid on, in this case, opposite sides of core  315 .  FIG. 3  shows conductive layer  320 A and conductive layer  320 B of, for example, a copper that is, for example, is a conductive material that serves as, for example, a power or ground plane or pathway or signal trace. A plane, such as a ground plane or power plane may simply be a conductive sheet or may be patterned as desired. Similarly, where conductive layer  320 A is a pathway or signal trace, the layer may be patterned. A film or sheet may be patterned using photolithographic and etch techniques. 
         [0020]    Overlying respective ones of conductive layer  320 A and conductive layer  320 B is insulating layer  325 A and  325 B. Insulating layer  325 A and insulating layer  325 B may be introduced as a film or sheet of, for example, a prepreg material to a thickness suitable to insulate conductive layer  320 A and conductive layer  320 B, respectively. Overlying respective lines of insulating layer  325 A and insulating layer  325 B is conductive layer  330 A and  330 B similar to conductive layer  320 A and  320 B, each of conductive layer  330 A and conductive layer  330 B may be a power or ground plane or pathway or signal trace. Where desired, each conductive layer may be patterned as is appropriate. The total number of conductive layers and insulating layers can be more or less than illustrated. 
         [0021]    Overlying conductive layer  330 A on a surface of core  310  are an array of contact points, lands or pads  335 . Contact points  335  are a conductive pattern resulting from an etching and plating process. Contact points  335  may be arranged in an array to correspond to an array of contact points, lands or pads of a package to be placed on core  310 . Overlying contacts points  335 , in one embodiment, is bonding material  340 . In one embodiment, bonding material  340  is a conductive adhesive such as an epoxy adhesive such as anisotropic film (ACF). In another embodiment, bonding material  340  may be a solder material. An advantage to a conductively adhesive for bonding material  340  is that it will tend to increase the reliability of the circuit board contact point to package contact point connection while providing a relatively minimal z-height contribution. 
         [0022]      FIG. 4  shows the structure of  FIG. 3  following the introduction of package  345  onto core  310 . In one embodiment, package  345  is a flip-chip package including device  350  such as a die including a microprocessor. In another embodiment, package  345  is a BBUL package. On a bottom side of package  345  (as viewed) the package includes an array of contact points, lands or pads  360  arranged, for example, as a land grid array. The array of contact points  360  may be aligned with one or more of contact points  335  on core  310 . In this manner, desired ones of the array of contact points  360  may be connected to contact points  335  using, for example, bonding material  340  (e.g., a conductive epoxy adhesive). 
         [0023]    A superior or device side of package  345  in the embodiment shown in  FIG. 4 , also, includes contact points, lands or pads  365 . Contact points  365  may be routed to signal lines or traces or planes associated with core  310  subsequent build up layers and/or a device that could be external to the ultimate printed circuit board that is fabricated. 
         [0024]      FIG. 5  shows the structure of  FIG. 4  with package  345  connected to core  310  and shows the addition of buildup layers to the printed circuit board structure. Buildup layers may be introduced using an HDI printed circuit board process wherein a film or sheet of conductive or insulative material is introduced. In the embodiment shown in  FIG. 5 , package  345  and die  350  extend from a superior surface (surface  332 A) of core  310 . Accordingly, a film or sheet of insulating or conductive material cannot be directly applied to core  310  as a conventional HDI printed circuit board process without contacting package  345  and/or die  350 . Therefore, in one embodiment, prior to applying an insulating or conductive material as a sheet or film, an opening having dimensions equivalent to the dimensions of the wider of package  345  and die  350  is made in the films where necessary to place the film(s) on core  310 . One way an opening may be made in a film or a sheet is by a laser cutting process. Once an opening is made, the film(s) may be introduced onto core  310 .  FIG. 5  shows insulating film  370  being introduced initially on core  310  and on surface  332 A of conductive layer  330 A. In one embodiment, insulating film  370 A is a prepreg material introduced to a desired thickness as an insulator in an HDI printed circuit board process. Overlying insulating layer  370 A is conductive film  375 A of, for example, a copper material. Conductive layer  375 A may be introduced as a sheet and, where necessary, patterned, using, for example, photolithography and etch techniques. The addition of buildup layers to core  310  may continue as desired.  FIG. 5  shows additional buildup layers of insulating film  380 A and conductive film  385 A to define a buildup layer portion on one side of core  310 . It is appreciated that where an opening are formed in a film prior to the film being applied to the core, the opening in such film need only be as large of an area as necessary or desired to surround package  345  and/or die  350 . Accordingly, an area of an opening of insulating layer  380 A and/or conductive film  385 A may be less than an area of openings in conductive film  375 A and/or insulating film  370 A.  FIG. 5  finally shows insulating films  370 B and  380 B and conductive films  375 B and  385 B defining another buildup layer portion on a second side of core  310 . 
         [0025]      FIG. 6  shows the structure of  FIG. 5  following the introduction of multiple buildup layers on core  310 . In this embodiment, two pairs of conductive and insulative layers constitute the buildup layers. It is appreciated, that the buildup layers may consist of less than or more than two pairs of buildup layers. Referring to  FIG. 6 , the structure shows insulating layer  370 A on a superior surface of core  310  and insulating layer  370 B on the bottom surface of core  310 . Overlying insulating layer  370 A is conductive layer  375 A and underlying insulating layer  370 B is conductive layer  375 B. Overlying conductive layer  375 A is insulating layer  380 A and underlying conductive layer  375 B is insulating layer  380 B. Overlying conductive layer  375 A is insulating layer  380 A followed by conductive layer  385 A. Underlying conductive layer  375 B is insulating layer  380 B followed by conductive layer  385 B. It is appreciated that in addition to introducing insulating and conductive layers or core  310 , a HDI printed circuit board process may be followed. This includes patterning conductive films as desired (e.g., through photolithography and etch techniques) and locating and forming conductive microvias by way of, for example, laser drilling and filling operation. 
         [0026]      FIG. 6  illustrates a printed circuit board including an embedded package therein. The z-height of the printed circuit board and package is equivalent to a z-height of the printed circuit board. In this embodiment, package  345  includes contact points, pads or lands on a superior on top side surface (as viewed) contact points or pads  365  provide an increased density of second level of interconnects that allows for signal breakout on the superior side of the board and improves signal integrity performance with shorter signal paths to component(s) that are placed on a superior side of the die. Embedding package  345  in a printed circuit board also eliminates the need for an interposer that has been used, for example, in package on package configurations, since the build-up layer portion around package  345  can function as an interposer. Further, power delivery is improved since decoupling capacitors can be mounted directly on top of die  350  as viewed (e.g., directly on top of a central processing unit or system on a chip). In another embodiment, one or more decoupling capacitors may be embedded. 
         [0027]    To form the structure of  FIG. 1 , the insulating and/or conductive build-up films of the printed circuit board may be applied with an opening to expose a surface of die  350  or the opening(s) may be cut in the film(s) after their introduction. Representatively, a die  350  can be a device operating at higher power where it may be desirable to include thermal dissipation. In such an embodiment, a heat spreader or other thermal solution may be introduced on an exposed surface of the die (see  FIG. 1 ). Additional devices (e.g., a DRAM device) can then be mounted beside the heat spreader using, for example, an embedded conducting film (e.g., a microstrip) to perform the input/output connection through microvias. 
         [0028]    In each of the embodiments described with reference to  FIG. 1  and  FIG. 2  and the process of  FIGS. 3-6 , a single component, a die, is embedded in a printed circuit board. In another embodiment, additional components may be embedded using the same techniques. 
         [0029]      FIG. 7  illustrates a computing device  400  in accordance with one implementation of the invention. Computing device  400  houses board  402 . Board  402  may include a number of components, including but not limited to processor  404  and at least one communication chip  406 . Processor  404  is physically and electrically coupled to board  402 . In some implementations the at least one communication chip  406  is also physically and electrically coupled to board  402 . In further implementations, communication chip  406  is part of processor  404 . 
         [0030]    Depending on its applications, computing device  400  may include other components that may or may not be physically and electrically coupled to board  402 . These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). 
         [0031]    Communication chip  406  enables wireless communications for the transfer of data to and from computing device  400 . The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. Communication chip  406  may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. Computing device  400  may include a plurality of communication chips  406 . For instance, first communication chip  406  may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and second communication chip  406  may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others. 
         [0032]    Processor  404  of computing device  400  includes an integrated circuit die packaged within processor  404 . In some implementations of the invention, the integrated circuit die of the processor includes one or more devices, such as transistors and CMOS implementations, that are formed in accordance with embodiments herein. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. 
         [0033]    Communication chip  406  also includes an integrated circuit die packaged within communication chip  406 . In accordance with another implementation, the integrated circuit die of the communication chip includes one or more devices, such as transistors and CMOS implementations, that are formed in accordance with implementations described above. 
         [0034]    In further implementations, another component housed within computing device  400  may contain an integrated circuit die that includes one or more devices, such as transistors and CMOS implementations, that are formed in accordance with implementations described above 
         [0035]    In various implementations, computing device  400  may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, computing device  400  may be any other electronic device that processes data. 
         [0036]    In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. The particular embodiments described are not provided to limit the invention but to illustrate it. The scope of the invention is not to be determined by the specific examples provided above but only by the claims below. In other instances, well-known structures, devices, and operations have been shown in block diagram form or without detail in order to avoid obscuring the understanding of the description. Where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics. 
         [0037]    It should also be appreciated that reference throughout this specification to “one embodiment”, “an embodiment”, “one or more embodiments”, or “different embodiments”, for example, means that a particular feature may be included in the practice of the invention. Similarly, it should be appreciated that in the description various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects may lie in less than all features of a single disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the invention.