PATENT DOCUMENT

Publication Number: US-10631410-B2
Application Number: US-201715710579-A
Country: US
Kind Code: B2

Title: Stacked printed circuit board packages

Abstract:
The present disclosure is related to printed circuit board packages and methods of assembly that may be used in the fabrication of electrical devices. Printed circuit board packages may be manufactured by stacking printed circuit board assemblies. Each printed circuit board assembly may have multiple printed circuit boards supported by a resin mold. The printed circuit board assemblies may be shaped to improve space utilization efficiency and to accommodate large electrical components that are attached to the printed circuit board package.

Claims:
What is claimed is: 
     
       1. A printed circuit board assembly comprising:
 a first bottom printed circuit board; 
 an integrated circuit electrically coupled to the first bottom printed circuit board; 
 a mold embedding the integrated circuit and attached to the first bottom printed circuit board at a bottom surface of the mold, wherein the mold comprises a first portion having a first height measured from the bottom surface to a first top surface of the mold, and a second portion having a second height measured from the bottom surface to a second top surface of the mold, wherein the second height is smaller than the first height; 
 a first top printed circuit board attached to the mold in the first surface; and 
 a second top printed circuit board attached to the mold in the second surface of the mold. 
 
     
     
       2. The printed circuit board assembly of  claim 1 , comprising a thru-mold via. 
     
     
       3. The printed circuit board assembly of  claim 1 , wherein the integrated circuit is electrically coupled to the bottom printed circuit board using a solder ball. 
     
     
       4. The printed circuit board assembly of  claim 1 , wherein the bottom printed circuit board comprises a multilayer printed circuit board. 
     
     
       5. The printed circuit board assembly of  claim 1 , wherein the integrated circuit comprises a system-on-a-chip. 
     
     
       6. A printed circuit board stack comprising:
 a first printed circuit board assembly comprising:
 a first printed circuit board; 
 a first integrated circuit electrically coupled to the first printed circuit board; and 
 a first mold embedding the first integrated circuit and attached to the first printed circuit board; and 
 
 a second printed circuit board assembly comprising:
 a bottom printed circuit board; 
 a second integrated circuit electrically coupled to the bottom printed circuit board; 
 a second mold embedding the second integrated circuit and attached to the bottom printed circuit board, wherein the second mold comprises a first region having a first height and a second region having a second height smaller than the first height; 
 a first top printed circuit board attached to the second mold in the first region; 
 a second top printed circuit board attached to the second mold in the second region; and 
 a thru-mold via embedded in the second mold and configured to electrically couple the first printed circuit board of the first printed circuit board assembly and the bottom printed circuit board of the second printed circuit board assembly through the first top printed circuit board. 
 
 
     
     
       7. The printed circuit board stack of  claim 6 , wherein the first top printed circuit board assembly comprises a solder pad of the thru-mold via. 
     
     
       8. The printed circuit board stack of  claim 7 , comprising a solder ball configured to electrically couple the first top printed circuit board and the solder pad of the thru-mold via. 
     
     
       9. The printed circuit board stack of  claim 7 , comprising an electrical component soldered to the second top printed circuit board, wherein the electrical component is not embedded by the second mold or the first mold. 
     
     
       10. The printed circuit board stack of  claim 6 , comprising an electrical component soldered to a bottom surface of the bottom printed circuit board opposite to top a surface of the bottom printed circuit board attached to the second mold. 
     
     
       11. The printed circuit board stack of  claim 10 , wherein the electrical component is a memory component. 
     
     
       12. The printed circuit board stack of  claim 6 , wherein the first integrated circuit comprises a network controller and the second integrated circuit comprises a system-on-chip. 
     
     
       13. The printed circuit board stack of  claim 6 , comprising a second printed circuit board attached to the second top printed circuit board of the second printed circuit board assembly. 
     
     
       14. The printed circuit board stack of  claim 13 , comprising a removable integrated circuit adaptor attached to the second printed circuit board. 
     
     
       15. A method to produce an electrical device, comprising:
 providing set of printed circuit board assemblies, wherein at least one printed circuit board assembly comprises:
 a bottom printed circuit board; 
 an electrical component coupled to the printed circuit board; 
 a mold embedding the electrical component and attached to the printed circuit board in a bottom surface of the mold, wherein the mold comprises a first region that has a first height and a second region that has a second height smaller than the first height; 
 a first top printed circuit board attached to the mold in the first region in a first top surface that is opposite to the bottom surface of the mold; and 
 a second top printed circuit board attached to the mold in the second region in a second top surface that is opposite to the bottom surface of the mold; and 
 
 attaching at least one non-embedded electrical component in an exposed surface of a top printed circuit board of the at least one printed circuit board assembly, wherein the top printed circuit board is disposed in the second region; and 
 stack the set of printed circuit board assemblies. 
 
     
     
       16. The method of  claim 15 , wherein the top printed circuit board comprises a removable integrated circuit adaptor configured to receive the at least one non-embedded electrical component.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-Provisional patent application of U.S. Provisional Patent Application No. 62/399,370, entitled “Stacked Printed Circuit Board Packages”, filed Sep. 24, 2016, which is herein incorporated by reference in its entirety and for all purposes. 
     BACKGROUND 
     The present disclosure relates generally to printed circuit boards for electrical devices. More specifically, this disclosure describes printed circuit board designs that allow stacking of multiple packages for a three-dimensional multi-layer printed circuit board structure. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electrical devices may employ electrical circuits that are implemented as integrated circuits and discrete components attached to printed circuit boards. Printed circuit boards are often flat structures that may present pads and terminals for the fixation of components. The flat structure of the printed circuit board may impose a constraint to the shape of the electrical device. In some devices, the flat shape of the printed circuit board results in an inefficient use of space in regions located above the printed circuit board. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     In one example, a printed circuit board assembly is described. The printed circuit board assembly may have a printed circuit board, an integrated circuit coupled to the printed circuit board and a mold fixed to the printed circuit board that embeds the integrated circuit. The mold may have a step down region, i.e., a region of lowered height. 
     In another example, a printed circuit board stack is described. The printed circuit board stack may a first printed circuit board assembly having a printed circuit board, an integrated circuit, and a mold attached to the printed circuit board that embeds the integrated circuit. The printed circuit board stack also includes a second printed circuit board assembly also having a printed circuit board, an integrated circuit, and a mold attached to the printed circuit board that embed the integrated circuit of the second printed circuit board assembly. The second printed circuit board assembly may also include a thru-mold via (TMV) that electrically couples the printed circuit boards of the first and the second printed circuit board assembly. 
     Another example provides an example of a method to produce a printed circuit board stack. The method may include processes for producing a set of printed circuit board assemblies having a printed circuit board, an electrical component coupled to the printed circuit board, and a mold attached to the printed circuit board that embeds the electrical component. The method may also include processes for attaching at least one non-embedded electrical component in an exposed surface of the printed circuit board, and for stacking the printed circuit board assemblies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a diagram of an electrical device that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 3  is a front view of a hand-held device that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 4  is a front view of portable tablet computer that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 5  is a diagram of a desktop computer that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 6  presents a front and a side view of a wearable electrical device that may benefit from the use of stacked printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 7  presents a printed circuit board stack having two printed circuit board assemblies and an electrical component, in accordance with an embodiment; 
         FIG. 8  presents a method to produce a printed circuit board stack as the one in  FIG. 7 , in accordance with an embodiment; 
         FIG. 9  presents a printed circuit board stack with a printed circuit board assembly having a step down region, in accordance with an embodiment; 
         FIG. 10  presents another example of a printed circuit board stack with a printed circuit board assembly having a step down region, in accordance with an embodiment; 
         FIG. 11  is a top diagram of a printed circuit board assembly illustrating having a step down region, in accordance with an embodiment; and 
         FIG. 12  is a diagram of a printed circuit board assembly illustrating examples of routing strategies within a printed circuit board stack, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     Many electrical systems include circuitry that may be implemented through the attachment of integrated circuits and passive components to printed circuit boards. Often, the components are attached to a flat printed circuit board. This shape leads to empty volumes in regions located above the components attached to the printed circuit board. In order to obtain compact electrical devices, rearrangements of printed circuit board shapes may allow better utilization of a vertical dimension (i.e., direction perpendicular to a printed circuit board) of the electrical device. 
     To that end, circuitry may be distributed along multiple stacked printed circuit board assemblies (e.g., a package-on-package structure, or PoP). A printed circuit board assembly (e.g., a system-in-package, or SIP) may include multilayer printed circuit boards and components attached to the printed circuit board, as detailed below. Printed circuit boards assemblies may also have molding materials to encase components and/or provide support to the printed circuit boards. Printed circuit board assemblies may also include vias, such as thru-mold vias, to provide electrical coupling between terminals of the printed circuit boards. Moreover, the printed circuit boards of the printed circuit board assemblies may be multilayer printed circuit boards. 
     The stacking between printed circuit board assemblies may take place through direct stacking, or through the use of solder balls. In some implementations, a printed circuit board assembly may be multi-height printed circuit board assemblies that present step-down portions, as detailed below. This arrangement may allow creation of space for disposition of components that may have some specific dimensional constraint. Furthermore, in some systems each of the stacked printed circuit board assemblies may be modular printed circuit board assembly. This design may facilitate reutilization of previously designed and manufactured printed circuit board assemblies when a change in a technology may lead to changes in some components of the circuitry. 
     With the preceding in mind, a general description of suitable electronic devices that may use the stacked printed circuit board assemblies described above is provided.  FIG. 1  is a block diagram of an electronic device  10 , in accordance with an embodiment of the present disclosure. The electronic device  10  may include, among other things, one or more processor(s)  12 , memory  14 , storage or nonvolatile storage  16 , a display  18 , input structures  22 , an input/output (I/O) interface  24 , network interface  26 , and a power source  28 . The various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements. Many of the circuitry of the hardware elements of the various functional blocks of  FIG. 1  may employ stacked printed circuit board assemblies to improve the efficiency in space utilization and/or facilitate fabrication of the hardware elements. It should be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device  10 . 
     By way of example, the electronic device  10  may represent a block diagram of a notebook computer  30 A depicted in  FIG. 2 , handheld devices  30 B,  30 C depicted in  FIG. 3  and  FIG. 4 , a desktop computer  30 D depicted in  FIG. 5 , a wearable electronic device  30 E depicted in  FIG. 6 , or similar devices. It should be noted that the processor(s)  12  and/or other data processing circuitry may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, firmware, hardware, or any combination thereof. Furthermore, the data processing circuitry may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . The data processing circuitry may be implemented using a single printed circuit board assembly, a printed circuit board assembly module, or distributed across multiple printed circuit board assemblies of a printed circuit board stack system. 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  and/or other data processing circuitry may be operably coupled with the memory  14  and the nonvolatile storage  16  to perform various algorithms. Such programs or instructions executed by the processor(s)  12  may be stored in any suitable article of manufacture or computer program product that includes one or more tangible, computer-readable media at least collectively storing the instructions or routines, such as the memory  14  and the nonvolatile storage  16 . The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. Moreover, programs (e.g., an operating system) encoded on the memory  14  or the nonvolatile storage  16  may also include instructions that may be executed by the processor(s)  12  to allow the electronic device  10  to provide various functionalities. A printed circuit board stack may include multiple functional blocks. In some implementation, a printed circuit board assembly may include one or multiple functional blocks, as detailed below. 
     In certain embodiments, the display  18  may be a liquid crystal display (e.g., LCD), which may allow users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more light emitting diode (e.g., LED, OLED, AMOLED, etc.) displays, or some combination of LCD panels and LED panels. 
     The input structures  22  of the electronic device  10  may allow a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may allow electronic device  10  to interface with various other electronic devices. The I/O interface  24  may include various communications interfaces, such as universal serial bus (USB) ports, serial communications ports (e.g., RS232), Apple&#39;s Lightning® connector, or other communications interfaces. The network interface  26  may also allow electronic device  10  to interface with various other electronic devices and may include, for example, interfaces for a personal area network (e.g., PAN), such as a Bluetooth network, for a local area network (e.g., LAN) or wireless local area network (e.g., WLAN), such as an 802.11x Wi-Fi network, and/or for a wide area network (e.g., WAN), such as a 3rd generation (e.g., 3G) cellular network, 4th generation (e.g., 4G) cellular network, or long term evolution (e.g., LTE) cellular network. The network interface  26  may include an interface for, for example, broadband fixed wireless access networks (e.g., WiMAX), mobile broadband Wireless networks (e.g., mobile WiMAX), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T) and its extension DVB Handheld (DVB-H), Ultra-Wideband (UWB), alternating current (AC) power lines, and so forth. 
     In some applications, input structures  22 , the I/O interfaces  24  and/or network interfaces  26  may employ radiofrequency (RF) circuitry modules. As further illustrated, the electronic device  10  may include a power source  28 . The power source  28  may include any suitable source of power, such as a rechargeable lithium polymer (e.g., Li-poly) battery and/or an alternating current (e.g., AC) power converter. The power source  28  may be removable, such as replaceable battery cell. 
     In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (e.g., such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (e.g., such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device  10 , taking the form of the notebook computer  30 A, is illustrated in  FIG. 2  in accordance with an embodiment of the present disclosure. The depicted computer  30 A may include a housing or enclosure  32 , a display  18 , input structures  22 , and ports of the I/O interface  24 . In one embodiment, the input structures  22  (e.g., such as a keyboard and/or touchpad) may be used to interact with the computer  30 A, such as to start, control, or operate a GUI or applications running on computer  30 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on display  18 . 
       FIG. 3  depicts a front view of a handheld device  30 B, which represents an embodiment of the electronic device  10 . The handheld device  30 B may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device  30 B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif.  FIG. 4  depicts a front view of another handheld device  30 C, which represents another embodiment of the electronic device  10 . The handheld device  30 C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device  30 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif. 
     The handheld devices  30 B and  30 C may each include similar components. For example, an enclosure  36  may protect interior components from physical damage. Enclosure  36  may also shield the handheld devices  30 B and  30 C from electromagnetic interference. The enclosure  36  may surround the display  18 , which may display indicator icons  39 . The indicator icons  39  may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. The I/O interfaces  24  may open through the enclosure  36  and may include, for example, an I/O port for a hard wired connection for charging and/or content manipulation using a connector and protocol, such as the Lightning connector provided by Apple Inc., a universal service bus (e.g., USB), one or more conducted radio frequency connectors, or other connectors and protocols. 
     User input structures  22 ,  40 , in combination with the display  18 , may allow a user to control the handheld devices  30 B or  30 C. For example, the input structure  40  may activate or deactivate the handheld device  30 B or  30 C, one of the input structures  22  may navigate a user interface of the handheld device  30 B or  30 C to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  30 B or  30 C, while other of the input structures  22  may provide volume control, or may toggle between vibrate and ring modes. In the case of the handheld device  30 B, additional input structures  22  may also include a microphone may obtain a user&#39;s voice for various voice-related features, and a speaker to allow for audio playback and/or certain phone capabilities. Portable devices  30 B and  30 C may include stacked printed circuit board assemblies described herein to improve the efficiency in space utilization. 
     Turning to  FIG. 5 , a computer  30 D may represent another embodiment of the electronic device  10  of  FIG. 1 . The computer  30 D may take any suitable form of computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer  30 D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer  30 D may also represent a personal computer (e.g., PC) by another manufacturer. A similar enclosure  36  may be provided to protect and enclose internal components of the computer  30 D such as a dual-layer display. In certain embodiments, a user of the computer  30 D may interact with the computer  30 D using various peripheral input devices, such as input structures  22  (e.g., the keyboard or mouse  38 ), which may connect to the computer  30 D via a wired I/O interface  24  and/or wireless I/O interface. 
     Similarly,  FIG. 6  depicts a wearable electronic device  30 E representing another embodiment of the electronic device  10  of  FIG. 1  that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device  30 E, which may include a wristband  44 , may be an Apple Watch® by Apple, Inc. However, in other embodiments, the wearable electronic device  30 E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The display  18  of the wearable electronic device  30 E may include a touch screen (e.g., LCD, OLED display, active-matrix organic light emitting diode (e.g., AMOLED) display, and so forth), which may allow users to interact with a user interface of the wearable electronic device  30 E. 
     With the foregoing in mind,  FIG. 7  illustrates a printed circuit board stack  100 . The printed circuit board stack  100  includes a top printed circuit board assembly  102  and a middle printed circuit board assembly  104 . The printed circuit board stack  100  may also include a memory component  106 , which may be a NAND memory device. Other printed circuit board assemblies, integrated circuits or other non-embedded electrical components may be used instead of the memory component  106  in a printed circuit board stack  100 . 
     Printed circuit board assembly  102  may include a mold  108  that encapsulates an integrated circuit  110  and may sit above multilayer printed circuit board  112 . Integrated circuit  110  may also be electrically coupled to the multilayer printed circuit board  112  with a solder ball  113 . As another example, printed circuit board assembly  104  may include a mold  120  displaced between a top printed circuit board  122  and a bottom printed circuit board  124 . The top printed circuit board  122  may also be a redistribution layer. Mold  120  is also encasing an integrated circuit  126 , which is soldered to the bottom printed circuit board  124  with solder balls  127 . A thru-mold via (TMV)  128  may also be embedded within the mold  120  to provide coupling between the top printed circuit board  122  and the bottom printed circuit board  124 . 
     A solder ball  130  may couple the top printed circuit board assembly  102  to the middle printed circuit board assembly  104 . In the example, solder ball  130  couples the multilayer printed circuit board  112  and the top printed circuit board  122 . As detailed below, the solder ball  130  may be placed above a pad of the TMV  128  to provide an electrical circuit route between the multilayer printed circuit board  112  and the bottom printed circuit board  124 . 
     It should be understood that the TMV  128  may provide other circuit routes for the middle printed circuit board assembly  104  to couple printed circuit boards in a printed circuit board stack  100 . For example, solder ball  132  may be used to couple the memory component  106  to the middle printed circuit board assembly  104 , and the TMV  128  may be used to provide an electrical connection between the multilayer printed circuit board  112  and the memory component  106 . 
     The printed circuit boards  112 ,  122  and  124  illustrated in the example an in the other examples illustrated herein may be multilayer printed circuit boards. In some examples, these printed circuit boards may be assembled as redistribution layers of the circuit. For example, a printed circuit board may be used to provide connection between multiple printed circuit board assemblies, as detailed below. 
     The flow chart  200  of  FIG. 8  illustrates a method to produce stacked printed circuit board assemblies as the ones described herein. A process to produce the printed circuit boards that may be in the top or the bottom of each of the printed circuit board assemblies (box  202 ). The printed circuit boards may be redistribution layers and may have routes and pads, as detailed below. Components that are embedded within a molding material may be soldered to the printed circuit boards (box  204 ). 
     Printed circuit boards may then be attached to mold (box  206 ). In some implementations, the mold may be a cured resin or rubber that is affixed to the printed circuit boards. In other implementations, the molding may take place by solidification of a liquid, resin or a gel that may be placed on the top of printed circuit board. The liquid, resin, or gel may then be cured in place to produce the mold. In some implementations, a step down region in the mold may be produced through carving, cutting or may be obtained through curing in place. The addition of mold (box  206 ) may produce printed circuit board assemblies, as described herein. 
     After the addition of the mold (box  206 ), components that are not embedded in the mold may be soldered (box  208 ) to the exposed surfaces of the printed circuit boards to produce printed circuit board assemblies that are ready for stacking. In some implementations, as discussed herein, a printed circuit board assembly may include one or more self-contained functional modules, as described above. The printed circuit board assemblies may be stacked (box  210 ) to produce a printed circuit board stack. The stacking may employ the use of solder balls, soldering of exposed pins of the printed circuit boards, wires, or any other appropriate method as specified in the design of the printed circuit board stack. 
     The printed circuit board stack  300  of  FIG. 8  provides another illustration of a packaging that uses multiple printed circuit board assemblies  304  and  306 . The printed circuit board stack may also be coupled to memory component  308  and an integrated circuit  310 . The memory component  308  may be for example, a NAND memory integrated circuit and the integrated circuit  310  may be, for example, a memory integrated circuit. In some implementations, integrated circuit  310  may be an adaptor for an integrated circuit such as a slot for a subscriber identification module (SIM) card for a mobile device, or a slot for removable flash memory. Note that the integrated circuit  310  is not embedded in the mold, and may be soldered to an exposed surface (e.g., a surface not attached to the mold). 
     Note that, in the example illustrated, integrated circuit  310  may have a significant height and width that may affect the dimensions of the printed circuit board stack  300 . To improve the efficiency in space utilization, the printed circuit assembly  306  may have a width that is smaller than the width of the printed circuit board stack  300 . Moreover, printed circuit board assembly  304  may present a step down region  311  to accommodate the dimensions of integrated circuit  310 . Materials in the step down region  311  may include mechanical components to reduce vibration, provide stiffness, or other mechanical advantages. For example, rubbery materials may be provided to add dampening properties, and stiff materials may be used to increase protection. Dielectric materials that may provide self-shielding properties to the regions of the assembly of the electronic device may also be added. Moreover, the step down region  311  may be used to allow air flow for heat dissipation, or addition of materials with thermal properties to facilitate heat dissipation. 
     Top printed circuit board assembly  306  may have a mold material  312  that encases an integrated circuit  314 . The integrated circuit  314  may employ solder balls  315  for coupling with printed circuit board  316  of the printed circuit board assembly  306 . The middle printed circuit board assembly  304  may have a mold  318  enveloping integrated circuits  320  and  322 . Integrated circuits  320  and  322  may be soldered to a lower printed circuit board  325 . The mold  318  is disposed on top of lower printed circuit board  325  and provides support for printed circuit boards  326  and  328 . Note that printed circuit board  326  is located in the step down region  311 , as discussed below. 
     The step down region  311  may be produced by having a mold  318  with the appropriate shape with a step down structure. Printed circuit board  326  may be placed in the top of mold  318  in the step down region and printed circuit board  328  may be placed in the step down region  311 , and printed circuit board  328  may be placed in the top of mold  318  in the elevated region to generate the printed circuit board assembly  304  with the step down region  311 . 
     In this illustration of an example of a printed circuit board assembly  304 , TMVs  330  may be used to be couple the bottom printed circuit board  315  to top printed circuit boards  326  and  328 . As discussed above, the TMVs  330  may be employed to route electrical circuit across electrical circuit components and integrated circuits of the printed circuit board stack. Note that solder balls  332  and  334  may be used to provide electrical coupling between the multiple modules of the printed circuit board stack  300 , such as printed circuit board assemblies  304  and  306 , integrated circuit  310  and memory component  308 . 
     The printed circuit board stack  400  illustrated in  FIG. 10  provides another example of increased space utilization efficiency. In this system, printed circuit board assembly  404  is attached to the multiple modules of the printed circuit board stack, each module having a distinct shape. For example, memory component  402  may have a width that is shorter than the printed circuit board assembly, which may leave a region  490  that may be use for a casing of an electrical device. Moreover, a printed circuit board assembly  406  may be attached to the top of printed circuit board assembly  404 . Integrated circuits  408  and  410  may also be attached to the top of printed circuit board assembly  404 . Note that integrated circuit  408  may have a height that is larger than that of printed circuit board assembly  406  and integrated circuit  410 . To accommodate this height difference, printed circuit board assembly  404  may have a step down region  492 , similar to the one described above. 
     The printed circuit board assembly  406  may have a mold  412  encapsulating an integrated circuit  414  that may be soldered to a bottom printed circuit board  420  via solder balls  418 . Similar, printed circuit board assembly  404  may have a mold  412  disposed between top printed circuit boards  442  and  462 , and a bottom printed circuit board  444 . Integrated circuit  446  may be electrically coupled to the bottom printed circuit board  444  through solder balls  448 , and integrated circuit  450  may be electrically coupled to the bottom printed circuit board  444  through solder ball  452 . Printed circuit board assembly  406  may also have TMVs  464  that couple top printed circuit boards  442  and  462  to bottom printed circuit board  444 . As mentioned above, TMVs  464  may be used to provide routing between the multiple integrated circuits and discrete components of the printed circuit board stack  400 . 
     The multiple modules of the printed circuit board stack  400  may be connected via solder balls. For example, integrated circuit  408  may be electrically coupled to top printed circuit board  462  via solder ball  460  and integrated circuit  410  may be coupled to printed circuit board  442  through solder balls  430 . Printed circuit board assembly  406  may be coupled to printed circuit board assembly  404  via solder ball  422 . The memory component  402  may be coupled to the bottom printed circuit board  444  of the printed circuit board assembly  404  using solder balls  480 . It should be noted that other methods may be used such as attaching wires or using metallic terminations (e.g., pins) for these attachments. 
     Note that integrated circuit  410  is directly attached to the top of printed circuit board  442 , whereas integrated circuit  416  is electrically coupled to printed circuit board  442  through at least printed circuit board  420 . This may be useful in situations where integrated circuit  416  may benefit from a shielding. This shielding may be provided by dielectric properties of mold  412 , or by a shielding from the printed circuit board  420 . Shielding may also be provided by additional structures added to printed circuit board assembly  406 . An integrated circuit  410  that may be self-shielded can be soldered directly to printed circuit board  442 . 
     As described above, different printed circuit board assemblies may be functional units. For example, printed circuit board assembly  404  may be a processing module of the printed circuit board stack  400 . In this example, integrated circuit  446  may be a processor or a system-on-a-chip and integrated circuit  450  may include a cache memory. Further, printed circuit board assembly  406  may be a network controller module of the printed circuit board stack  400  and integrated circuit  414  may further be a network controller chip. In this illustration, integrated circuit  410  may include a controller for an input/output device, and integrated circuit  408  may be an adaptor for a removable flash memory card. In this example, a change in the specification of the network adaptor may be accommodated by changes in the printed circuit board assembly  406 , without changing the remaining components of the printed circuit board stack  400 . 
     As mentioned above, a printed circuit board assembly may have multiple thru-mold vias (TMV) for electrical coupling between modules and components of stacked printed circuit board assemblies.  FIG. 11  is a top diagram of a printed circuit board assembly having a step down region. Top view  520  provides an example of the printed circuit board assembly. Top printed circuit boards  522 , as well as a step down region  524  having a second printed circuit board  526 , are illustrated. Note that top printed circuit board  522  may include TMV solder pads  528 , which are exposed electrical terminations for the TMVs of the printed circuit board assembly, as discussed above. Note also that the top printed circuit board  522  may also have electrical pads  530 , which are not directly coupled to TMVs and may be used for redistribution of connections in a redistribution layer. 
     The printed circuit board stack  600  of  FIG. 12  illustrates another example of the systems described herein. In this example, a single printed circuit board assembly  608  may be electrically coupled to integrated circuits  602 ,  604  and  606 . Printed circuit board assembly  608  may include a mold  622  disposed between a top printed circuit board  624  and bottom printed circuit board  626 . Printed circuit board assembly  608  may also include TMVs  628  with TMV solder pads  630  in the top printed circuit board  624 . Top printed circuit board  624  may also have electrical pads  632  which, in this example are coupled through a route  634 . Electrical pads  632  and route  634  may create an electrical circuit between integrated circuit  602  and integrated circuit  604  through the top printed circuit board  624 . Note that another route between integrated circuits  602  and  604  may be made through TMV  628  and bottom printed circuit board  626  (not illustrated in this diagram). 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20170920
Publication Date: 20200421
Grant Date: 20200421
Priority Date: 20160924
Inventors: PROVENCHER, COREY S.
LEE, MENG CHI
WALTERS, DEREK J.
SPRAGGS, IAN A.
CARSON, Flynn P.
CHAUHAN, Shakti S.
JARVIS, DANIEL W.
PAKULA, DAVID A.
ZHAI, JUN
YEH, MICHAEL V.
CRUMLIN, ALEX J.
PYPER, DENNIS R.
SALEHI, AMIR
VO, VU T.
STEPHENS, GREGORY N.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/341", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/144", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/141", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/284", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/115", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/113", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/3436", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10159", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10674", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/0014", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10674", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/0014", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/113", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/341", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02P70/611", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10159", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/284", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/3436", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/115", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/144", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/15192", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/15311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/16225", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02P70/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02P70/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/144", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/113", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10159", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10674", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/3436", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 61685987