PATENT DOCUMENT

Publication Number: US-10129979-B2
Application Number: US-201615274302-A
Country: US
Kind Code: B2

Title: PCB assembly with molded matrix core

Abstract:
Methods and devices related to the design and fabrication of molded cores for printed circuit board assemblies and system-on-package (SIP) devices are discussed. The discussed printed circuit board assemblies may have multiple electrical components embedded in a molded core matrix and forming electrical connections with one or more printed circuit boards attached to the molded core matrix. Methods for sourcing of electrical components and production of the molded cores and printed circuit board assemblies are also discussed. The methods and devices may increase a volumetric density of electrical components in printed circuit board assemblies and provide improved mechanical properties to the electrical circuit device.

Claims:
What is claimed is: 
     
       1. A printed circuit board assembly comprising:
 a first printed circuit board; 
 a first electrical component mounted and electrically coupled to the first printed circuit board and having a first height measured along a direction perpendicular to the first printed circuit board; 
 a second electrical component mounted and electrically coupled to the first printed circuit board, and having a second height measured along the direction perpendicular to the first printed circuit board, the second height substantially identical to the first height; 
 a second printed circuit board separated from the first printed circuit board by a distance substantially identical to the first height, wherein the first electrical component and the second electrical component are mounted to and electrically coupled to the second printed circuit board; and 
 a mold occupying all portions of a first region of the first printed circuit board that are unoccupied by any electrical component disposed between the first printed circuit board and the second printed circuit board. 
 
     
     
       2. The printed circuit board assembly of  claim 1 , wherein the mold as measured in the direction perpendicular to the first printed circuit board is substantially identical to the first height. 
     
     
       3. The printed circuit board assembly of  claim 1 , wherein the first electrical component and the second electrical component each include at least one dimension that complies with a standard for a case size. 
     
     
       4. The printed circuit board assembly of  claim 1 , wherein the first height of the first electrical component is substantially 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.25 mm 1.5 mm, 1.6 mm, 2.0 mm, 2.5 mm, 3.2 mm, 4.5 mm, 5.0 mm, 6.3 mm, 5.1 mm, 7.3 mm, or 7.4 mm. 
     
     
       5. The printed circuit board assembly of  claim 1 , comprising a third electrical component disposed between the first printed circuit board and the second printed circuit board and mounted only to the first printed circuit board. 
     
     
       6. The printed circuit board assembly of  claim 5 , comprising a fourth electrical component disposed in a surface of the first printed circuit board opposite to the surface of the first printed circuit board to which the first electrical component is mounted. 
     
     
       7. The printed circuit board assembly of  claim 1 , wherein the first printed circuit board comprises a second region adjacent to the first region, wherein the second region does not comprise the mold. 
     
     
       8. The printed circuit board assembly of  claim 7 , wherein the second region comprises a third printed circuit board and a second mold occupying all portions of the second region of the printed circuit board that are unoccupied by any electrical component disposed between the first printed circuit board and the third printed circuit board. 
     
     
       9. The printed circuit board assembly of  claim 7 , wherein the second region of the first printed circuit board comprises a flexible region of the printed circuit board. 
     
     
       10. The printed circuit board assembly of  claim 1 , wherein the first printed circuit board is a multilayer printed circuit board. 
     
     
       11. The printed circuit board assembly of  claim 1 , wherein the first printed circuit board comprises a first shielding layer and the second printed circuit board comprises a second shielding layer, and wherein the mold comprises at least one via that electrically couples a first shielding pad in the first shielding layer and a second shielding pad in the second shielding layer. 
     
     
       12. The printed circuit board assembly of  claim 1 , wherein the first electrical component comprises a resistor, a capacitor, an inductor, or a semiconducting component. 
     
     
       13. A device comprising:
 a first electrical component having a first height measured along a direction perpendicular to a plane; 
 a second electrical component having a first length substantially similar to the first height, and disposed such that the first length is oriented the direction perpendicular to the plane; and 
 a mold supporting the first electrical component and the second electrical component, wherein the mold has a thickness substantially similar to the first height as measured along the direction perpendicular to the plane, and wherein the first electrical component comprises a first termination disposed on a top of the mold and a second termination at a bottom of the mold, and wherein the second electrical component comprises a third termination disposed on the top of the mold and a fourth termination disposed on the bottom of the mold. 
 
     
     
       14. The device of  claim 13 , wherein the device is attached to a first printed circuit board on a first surface of the mold parallel to the plane, wherein the attachment of the first printed circuit board to the mold electrically couples the first electrical component and the second electrical component to the first printed circuit board, and the device is configured to be attached to a second printed circuit board on a second surface of the mold opposite to the first surface of the mold, wherein the attachment of the second printed circuit board to the mold electrically couples the first electrical component and the second electrical component to the second printed circuit board. 
     
     
       15. The device of  claim 13 , wherein the device comprises a solder ball in contact with the second electrical component, wherein the first length includes a dimension of the solder ball and the first length is substantially identical to the first height. 
     
     
       16. The device of  claim 13 , comprising a third electrical component supported by the mold and disposed such that a dimension of the third electrical component measured along a direction perpendicular to the plane is substantially smaller than the first height. 
     
     
       17. The device of  claim 13 , wherein the first electrical component comprises a resistor, a capacitor, an inductor, or a semiconducting component.

Description:
BACKGROUND 
     The present disclosure relates generally to printed circuit board and printed circuit board assemblies, and more specifically, to printed circuit board assemblies that may employ molded cores that in the design and fabrication of the electrical devices that may include printed circuit boards. 
     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 and systems may include multiple electrical circuits to implement analog and digital computations, perform logic functions, transmit data over communication channels, obtain sensor data, and other related functions. Several of the electrical circuits may be implemented through soldering of electronic components to printed circuit boards (PCBs). To that end, PCBs may contain pads that provide electrical contacts for the terminals of the electrical components, and traces that provide electrical routes and connections between the pads electrical components. 
     Usually, the design and fabrication of printed circuit board assemblies involve attachment of each electrical components to a single PCB side of a PCB. Moreover, the attachment between the electrical components to the PCB is usually made through individual attachment of electrical components to the printed circuit board. The PCBs with appropriately attached electrical components may form a printed circuit board assembly, which may be incorporated into the electrical devices during manufacturing. This type of construction may lead to inefficient use of the available space, uneven mechanic properties throughout the printed circuit board assembly, and quality control issues during the assembly. 
     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 embodiment, a printed circuit board assembly is described. The printed circuit board assembly may include a first printed circuit board having a first and a second electrical component mounted to it. Heights of the first and the second components, as measured along a direction perpendicular to the first printed circuit board, may be substantially identical. The printed circuit board assembly may have a second printed circuit board such that the first and the second electrical component are also mounted to the second printed circuit board. The printed circuit board assembly may also have a mold that occupies all portions between the first and the printed circuit board that are unoccupied by any electrical component that may be disposed between the first and the second printed circuit board. 
     In another embodiment, a device is provided. The device may include a first electrical component and a second electrical component, both of which may have substantially similar heights as measured along a direction perpendicular to a specific plane. The device may also have a mold that supports the first and the second electrical components. Further, the mold may have a thickness substantially similar to the height of the first and the second electrical components. 
     A method to produce printed circuit boards is also discussed. The method may include a disposition of a set of electrical components on a place such that heights of the electrical components of the set of electrical components are substantially similar, the heights being measured in a direction perpendicular to the plane. The method may also include an application of mold material about the set of electrical components such that the mold has a thickness substantially similar to the heights of the electrical components. 
    
    
     
       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 inclusion of one or more printed circuit board assemblies with a core matrix, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer that may include printed circuit board assemblies, in accordance with an embodiment; 
         FIG. 3  is a front view of a hand-held device that may include a printed circuit board assembly, in accordance with an embodiment; 
         FIG. 4  is a front view of portable tablet computer that may include a printed circuit board assembly, in accordance with an embodiment; 
         FIG. 5  is a diagram of a desktop computer that may benefit from the inclusion of one or more 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 include a printed circuit board assembly, in accordance with an embodiment; 
         FIG. 7  presents a perspective view of a printed circuit board assembly with a molding disposed on top of a PCB and that may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 8  presents a perspective view of a printed circuit board assembly with a molding disposed between two PCBs and that may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 9  presents a front view of a printed circuit board assembly with a molding disposed between two multilayer PCBs and that may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 10  presents a front view of a printed circuit board assembly with a molding disposed between two PCBs, solder balls being used to facilitate mounting of electronic components, and that may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 11  presents a front view of a printed circuit board assembly presenting a region with molding disposed between two PCBs and a second region without a molding wherein the printed circuit board assembly may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 12  presents a front view of a printed circuit board assembly presenting a molding in a first region of the printed circuit board assembly and a second molding with a different thickness in a second region of the printed circuit board assembly, wherein the printed circuit board assembly may be used in conjunction with any of the devices of  FIGS. 1-6 , in accordance with an embodiment; 
         FIG. 13  illustrates a method to produce a printed circuit board assembly such as the printed circuit board assemblies illustrated in  FIGS. 7-13 , in accordance with an embodiment; and 
         FIG. 14  illustrates a perspective view of a shielded printed circuit board assembly that may be used in conjunction with any of the devices of  FIGS. 1-6 . 
     
    
    
     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. 
     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. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     Some of the descriptions may employ terms such as “coupling” or “connected” between two devices. Terms such as “coupled” and “electrically coupled” are intended to mean that the two devices may form an electrical circuit of some kind while “directly coupled” or “directly connected” is intended to mean that there is a physical connection between the two devices. Terms such as “operably coupled” are intended to mean that the two devices may be coupled in a manner that allows for proper function of the modules. 
     The disclosed embodiments relate to systems and devices for the design, fabrication, and utilization of printed circuit board assemblies that may present a molding material that forms a core of the printed circuit board assembly. The molding material may embed multiple electronic components to obtain a functional module of the electrical device. Such printed circuit board assembly may be a system-in-package (SIP). The use of molding materials may have the benefit of increasing the amount electrical components in a volume by decreasing the amount of empty space in the printed circuit board assembly. 
     In some applications, the molding material with embedded electronic components may be attached to a printed circuit board (PCB) to form a molding core matrix for the printed circuit board assembly. The molding material may provide mechanical stiffness to a region of the printed circuit board, which may reduce vibrations and/or improve resistance against impact. The molding material may also facilitate the assembly of the printed circuit board by allowing a single step soldering between a single core matrix and the PCBs instead of individual soldering of each components. 
     Moreover, the design and fabrication methods may lead to a printed circuit board assembly that may have multiple PCBs, and in some embodiments, an electrical component may be attached to more than one PCB. To that end, electrical components may be arranged based on their dimensions and disposition of the terminals. The use of standard case sizes for the electrical components may further facilitate the production of printed circuit board assemblies with molded core. The PCB assemblies described herein may also have multiple regions having molds with distinct thicknesses, and flexible regions not affixed to a mold or molding material. Printed circuit board assemblies with molded matrix, as described herein, may also have shielding layers and constructs, as detailed below. 
     With the preceding in mind, a general description of suitable electronic devices that may include and use the printed circuit assemblies that include the mold matrix cores 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 memory  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. Embodiments of the printed circuit board assembly or SIPs described herein may be used in the circuitry of the various functional blocks of  FIG. 1  to improve a performance of software and 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 . 
     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. 
     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 3 rd  generation (e.g., 3G) cellular network, 4 th  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 be implemented in SIPs that include electrical circuits formed by the PCBs and the attached electrical components and are responsible for performing part of the functions described above. Note that a SIP may be integrated into the device through exposed terminals that may be disposed in flexible regions of the printed circuit board assembly, or through sockets and plugs disposed in the PCB. 
     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. The input structures  22  may also include a headphone input to provide a connection to external speakers and/or headphones. 
     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. 
     As discussed above, electronic devices, such as electronic devices  30 A-E described above may include functionalities that may be implemented with SIPs that may integrate multiple electrical components into an electrical circuit. Printed circuit board assembly  100  illustrated in  FIG. 7  provides an example of such a SIP. The printed circuit board assembly may include a multilayer PCB  102  that may have routes and pads stenciled or printed in its surface. 
     Electrical components such as discrete components  104 A,  104 B, and  104 C may be attached to a surface of the PCB  102 . Moreover, other types of electrical components such as integrated circuits  106 A,  106 B, and  106 C may also be attached to a surface of the PCB 102 . Note that electrical components may include but are not limited to integrated circuits  106 A-C, or discrete components  104 A-C, such as resistors, capacitors, and inductors, or semiconducting components such as transistors, diodes, and other electrical components known in the art. Moreover, note that integrated circuits  106 A-C may be processors, programmable logic devices (PLD), memory elements, digital circuits, amplifiers, oscillators, and other electrical devices that may be packaged in integrated circuits. 
     The PCB  102  may have a molding material  108  that surrounds a volume on the top of the PCB  102  not occupied by any of the electrical components, such as discrete components  104 A-C or integrated circuits  106 A-C. Note that the electrical components may directly coupled to PCB  102 , i.e., the molding material does not prevent physical contact between discrete components  104 A-C and integrated circuits  106 A-C. The molding material  108  may facilitate the construction and fabrication of the printed circuit board assembly, as detailed below. Moreover, the material  108  may provide mechanical stiffness to the printed circuit board assembly, which may decrease damage from impact and/or vibrations suffered by the electrical device. 
     Note that the thickness of the molding material  108 , as measured along a direction perpendicular to the PCB  102  surface, may be determined by the dimension of the tallest electronic component, such as discrete component  104 A. Moreover, note that the printed circuit board assembly  100  may include large empty volumes (i.e., volumes without electrical components) within the molding material  108  such as the regions above integrated circuits  106 A-C. The printed circuit board assembly  200  of  FIG. 8  illustrates a design that reduces the empty volumes, which may lead to smaller electrical devices. 
     To that end, printed circuit board assembly  200  has a bottom PCB  202  and a top PCB  204 , with electrical components such as components  206 A,  206 B,  206 C,  208 A, and  208 B placed between the bottom PCB  202  and the top PCB  204 . A thru-mold via  207  may also be used to couple the bottom PCB  202  and the top PCB  204 . The components  206 A-C, and  208 A-B, and the thru-mold via  207  may be embedded within a molding material  210 . 
     Note that some components, such as component  206 B and thru-mold via  207  may be directly coupled to the bottom PCB  202  and the top PCB  204 . Other electrical components such as component  206 A and  206 C may be physically contacting both the bottom PCB  202  and the top PCB  204 , but it may be directly coupled to only one of the two PCBs  204  and  206 . Furthermore, component  208 A may be directly coupled with the bottom PCB  202  while component  208 B may be directly coupled with the top PCB  204 . 
     In the illustrated printed circuit board assembly  200 , IC  212 A and  212 B, and two-terminal electrical components  212 C may be coupled to the top PCB  204 . Note that the ICs  212 A and  212 B, and electrical components  212 C are coupled to the surface of top PCB  204  opposite to the molding material  210  and are not embedded within molding material  210 . A second molding material  214  may be disposed to enclose ICs  212 A and  212 B, and electrical components  212 C. Due to the reduced height of components  212 A-C relative to components  206 A, the second molding material  214  may be thinner than the molding material  210 . As a result, the density of electrical components may increase, which may lead to reduction of the dimensions of the electrical device employing the printed circuit board assembly. 
     As mentioned above, electrical component  206 B may be electrically coupled to both the bottom PCB  202  and the top PCB  204 . Moreover, a thru-mold via  207  may be incorporated in the printed circuit board assembly  200  to couple electrically the bottom PCB  202  and the top PCB  204 . Note that this allows the design of an electrical circuit that is shared across the bottom PCB  202  and the top PCB  204 . The thru-mold via  207  may also allow an electrical coupling between electrical components mounted to the top PCB  204 , such as IC  212 A and electrical component  208 B, to the bottom PCB  202 . In some implementations, the resulting electrical coupling is a resistive electrical coupling. 
     As discussed above, a component may be substantially in physical contact with both the bottom PCB  202  and the top PCB  204 , but be only directly coupled to one of the layers, such as electrical component  206 A. This may be accomplished by adequate placement of exposed terminals in the PCBs  202  and  204  relative to the placement of the terminals of the electrical component  206 A. For example, if a direct coupling between electrical component  206 A and bottom PCB  202  is desired, the contact region between the terminals of component  206 A should be aligned with a conductive region (e.g., a pad) of the bottom PCB  202 . Accordingly, if the coupling between electrical component  206 A and top PCB  204  is undesirable, the contact region between the terminals of component  206 A and the top PCB  204  should not have a substantial resistive nor capacitive coupling (i.e., the contact region should be electrically insulated). 
     As discussed above, multiple electrical components may be in physical contact with both the bottom PCB  202  and the top PCB  204 . To that end, it may be useful to have electrical components that follow a standard height (as measured along a dimension perpendicular to the surface of the PCBs  202  and  204 ), and use a molding material  210  with a thickness substantially close to that height. For example the electrical component may be selected from standards to provide a prescribed height of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.25 mm 1.5 mm, 1.6 mm, 2.0 mm, 2.5 mm, 3.2 mm, 4.5 mm, 5.0 mm, 6.3 mm, 5.1 mm, 7.3 mm, or 7.4 mm, or any other adequate height. The standardized height is not limited to metric units and may be prescribed in imperial units. Standards, such as the ones defined by the Electronics Industries Alliance (EIA) may facilitate an identification of an appropriate height. 
     Note that, the since the electrical components may be coupled to either one of the printed circuit boards  202  and  204  or to both of them, orientation of the electrical components may be freely adjusted so that the height of the electrical component matches the chosen thickness for the molding material  210 . For example, if the thickness of the molding material  210  is 2.0 mm, a EIA  2012  capacitor may be rotated such that its length (prescribed to be 2.0 mm) is perpendicular to the PCB  202  while a EIA  2520  inductor may be rotated such that its width (prescribed to be 2.0 mm) is perpendicular to the PCB  202 . It may be possible to employ electronic components with heights slightly smaller than the chosen thickness for the molding material  210  by using conductors such as solder ball, as detailed below. It may also be possible to employ electronic components with heights substantially smaller than the chosen thickness for the molding material  210  by coupling it to a single PCB (e.g., PCB  210 ), as detailed below. 
     It should be understood that the PCBs  202  and  204  in the printed circuit board assembly  200  may be single-layer PCBs or a multi-layer PCBs.  FIG. 9  illustrates a front view of a printed circuit board assembly  300  in which a bottom PCB  302  is a 3-layer PCB with layers  304 A,  304 B, and  304 C. A top PCB  306  of the printed circuit board assembly is also a 3-layer PCB with layer  308 A,  308 B, and  308 C. Each layer  304 A-C and  308 A-C may have a wiring layout and pads to establish connections with respective electrical components such as  310 A,  312 A and  312 B, and thru-mold via  310 B. In some implementations, any of the layers  304 A-C and  308 A-C may be shielding layers, with a layout that mitigates interference between the printed circuit board assembly  300  and neighboring electrical devices. In some implementations, any of the layers  304 A-C and  308 A-C may be grounding layers that may improve the quality of ground connections in high frequency circuits that may be implemented in the printed circuit board assembly  300 . 
     All the electrical components and the thru-mold vias are embedded by the molding material  314 , forming a core  313  of the PCB assembly  300 . Note that the components in the core  313 , such as electrical components  310 A,  312 A,  312 B, and thru-mold via  310 B may be directly coupled to any of the layers  304 A-C of the PCB  302 , or layers  308 A-C of PCB  306  to which the components physically connect. For example, a pad  315  of PCB  302  designed to connect to a terminal of electrical component  312 A may be located in a second layer  304 B. Note also that the multilayer PCBs  302  and  306  may have other coupled electronic components that are not embedded in the molded core  313 , such as electrical component  316  located on a surface of multi-layer PCB  306  opposite to the core  313 , and component  318  embedded within layer  308 B of the multi-layer PCB  306 . 
     Electrical components may be mounted to PCBs through point-to-point mounting, direct soldering, surface-mount technology (SMT) methods, through-hole connection, and other appropriate methods. The printed circuit board assembly  400  illustrated in  FIG. 10  provides an example where the electrical coupling between an electrical component and a PCB may be facilitated by other devices. Printed circuit board assembly  400  has a two-layer lower PCB  402  that includes layers  404 A and  404 B and a two-layer top PCB  406  that includes layers  408 A and  408 B. The PCB assembly  400  also has electrical components  410 ,  412 ,  416 A, and  416 B embedded in a molding material  418 . 
     In this example, electrical components  410  and  412  may be electrically coupled to both the bottom PCB  402  and top PCB  406 . Note that electrical component  410  is in direct physical contact with both PCB layers  402  and  406 , whereas electrical component  412  is direct contact only with bottom PCB  402 . The electrical coupling between electrical component  412  and top PCB  406  takes place via solder ball  414 . As discussed above, the thickness of the molding material  418  may be determined by the tallest electrical component  410 , as measured along a direction perpendicular to the PCBs  402  and  406 . The solder ball  414  may facilitate connection between an electrical component  412 , which may be shorter than electrical component  410  and, thus, shorter than the thickness of the molding material  418 . 
     Placement of other conductive materials may be used in place of the solder ball  414  to facilitate the assembly of electrical components having different heights or heights different from a dimension standard being employed in the printed circuit board assembly  400 . In the example, the solder ball  414  may allow the PCBs  402  and  406  to be substantially parallel to each other despite the distinction in heights between electronic components  410  and  412 . 
     As mentioned above, molding material may provide changes in the mechanical properties to of a printed circuit board assembly such as increased stiffness. In some situations, however, it may be desirable for a region of a printed circuit board assembly to have flexibility. The printed circuit board assembly  500  illustrated in  FIG. 11  allows for flexibility of different regions that may be adjusted, as desired, for use in various applications. The printed circuit board assembly  500  may have a bottom PCB  502  having two layers and, a top PCB  504 . The printed circuit board assembly also includes electronic components  506 A and  506 B which may be directly coupled to PCBs  502  and  504 , electronic component  508 A that may be directly coupled to PCB  502  and electronic components  508 B,  510 A,  510 B, and  510 C that may be directly coupled to PCB  504 . The printed circuit board assembly may have a flexible region  512  and a non-flexible region  514 . The non-flexible region  514  may be stiffer due to the presence of a molding material  516  that is disposed between the bottom PCB  502  and top PCB  504 . While in this example, the illustrated bottom PCB  502  is shorter than top PCB  504 , a printed circuit board assembly  500  may have a flexible region  512  having more than one PCB, without a molding material with thickness that provides stiffness to the flexible region  512 . 
     In some applications, the flexible region  512  may have connector in the top PCB  504  that may be inserted into a slot of an electrical device to obtain a robust integration between the printed circuit board assembly  500  and the electrical device. In applications where an electrical component may have a specification for physical space clearance, the electronic component may be added to a flexible region  512 . Note also that in some applications, the flexible region  512  may be used to obtain a shape for the printed circuit board assembly  500  that fits inside a region of the electrical device with a corresponding shape. 
     To obtain more flexibility in the shape of a printed circuit board assembly, multiple molded cores may be used.  FIG. 12  illustrates a printed circuit board assembly  600  that has two different molded cores. The printed circuit board assembly  600  may have a first PCB  602 , a second PCB  604 , and a 4-layer PCB  620 . The PCBs  602 ,  604 , and  620  may be coupled to electrical components  606 A,  608 A,  608 B,  616 A,  616 B,  616 C,  618 A and thru-mold vias  606 B and  618 B. The region  612  of the printed circuit board assembly  600  may have a first molded core with a molding material  622  embedding electrical components  606 ,  608 A,  608 B, and thru-mold via  606 B. The thickness of molding material  622  is determined by the height of electrical component material  606 A. 
     The region  614  of the printed circuit board assembly  600  may also have second molded core with a molding material  624  embedding electrical components  618 A,  616 C, and thru-mold via  6188 . Note the thickness of molding material  624  is smaller than the thickness of molding material  622 . This arrangement may allow an improved arrangement of the electronic components and PCBs within the printed circuit board assembly  600 . Note further that, based on a mechanical specification, the molding material  622 , and the molding material  624  may be separated, allowing flexibility in the region of top PCB  604  between region  612  and region  614 . In some applications, molding materials  622  and  624  may be formed from a single application of the resin. 
     The printed circuit board assemblies  300 ,  400 ,  500 , and  600 , as discussed above and illustrated in  FIGS. 7-12 , include molded cores. The use of molded cores may facilitate assembly of printed circuit board assemblies by allowing for simplified attachment and shipment of parts, as detailed bellow. Flow diagram  700  in  FIG. 13  provides an illustration of a method to assemble a printed circuit board assembly with a PCB with a molded core. To that end, the electronic components  702 A,  702 B,  702 C,  704 A, and  704 B may be aligned with respect to a surface  730 . Electronic components may be placed on surface  730 , as is the case with electronic components  702 A,  702 B,  702 C, and  704 A. 
     A thickness  732 , measured in a direction perpendicular to surface  730 , may be determined as the height of the tallest electronic component. As discussed above, the use of standardized case sizes for the components may be beneficial for this arrangement. Note that electronic components may be rotated to obtain a height substantially similar to thickness  732 . In some situations the component may be rotated to obtain a height that is substantially identical to thickness  732 . Note further that some of the components may be arranged such that its height is not the one that approximate thickness  732 . In some applications, where an electronic component may be shorter than thickness  732 , a solder ball or some other conductive segment may be placed to obtain the final desired height, as discussed above. 
     Some components, such as electronic component  704 B, may not be on surface  730  but may be part of the molded core, to be coupled to a PCB, as detailed below. Electrical component  704 B may be disposed such that its top is aligned with a top of the molded core, based on the thickness  732 . The arrangement may be enforced by the addition of a piece of mold  705  of adequate size between the electrical component  704 A and  704 B, or any other technique compatible with method  700 . 
     In a molding injection process  750 , a molding material  706  may be placed in the regions of the molded core that are not occupied by the electrical components  702 A,  702 B,  702 C,  704 A, and  704 B. The molding material may have a thickness  732  substantially similar to the height of the tallest electronic component. Moreover, a hole in the mold may be produced and filled with conductive material to form a thru-mold via  708  with a height similar to thickness  732  to form the molded core  734 . Note that the terminations of the electrical components  702 A,  702 B,  702 C,  704 A, and  704 B and of the thru-mold via  708  are exposed in the surfaces of the molded core  734  to allow coupling between the electrical components and the printed circuit boards, as detailed below. 
     A bottom PCB  710  and a top PCB  712  may be affixed to molded core  734  in a soldering process  754 . The PCBs  710  and  712  should be aligned with the molded core  734  such that the pads in PCBs  710  and  712  are substantially in contact with the electronic components of the molded core  734 . The fixation may be done using SMT techniques such as reflow oven methods with solder paste, gas convections, focused infrared soldering, and other known methods. Since the electrical components are already arranged within the molded core  734 , placement of the molded core is less complex than placement of multiple individual components. Care should be taken to avoid solder bridging during the single step fixation of the PCB to multiple components. 
     Further attachment of electrical components such as integrated circuits  714 A,  714 B, and  714 C to the top of PCB  712  may take place in a second soldering process  756 . Note that in this second soldering process, each part is placed individually for soldering on PCB  712 , as opposed to the soldering process  754  discussed above. A second molding placement process  758  may then take place to introduce a second molding material  716  that encapsulates electrical components  714 A,  714 B, and  716 A. 
     Note that process  756  and  758  may be replaced by a first molding injection process similar to process  750 , to produce a core molding that includes electronic components  714 A,  714 B, and  714 C, and a process similar to soldering process  754  to affix this core molding to the top of PCB  712 . In general, the order of the processes may be changed based on a convenience of the production of printed circuit board assemblies. 
     The production of a core molding separate from the PCB may provide some flexibility in the process of fabrication. For example, the selection and arrangement of individual parts, as well as the molding injection (process  750 ) may take place in a location distinct from the location where PCBs  710  and  712  are produced. The PCBs  710  and  712  and a finalized molded core  734  may be shipped to a third location for soldering and finalization of the package. Moreover, the mechanical properties of the finalized printed circuit board assembly with a molded core  734  may reduce the damage incurred while shipping printed circuit board assemblies or electrical devices containing the printed circuit board assemblies. 
     The molded core  734  may also be considered a module in the design of a printed circuit board assembly. For example, if two distinct circuitries employ the same electrical design but have a different circuit topology (e.g., a wiring diagram), it may be possible to reuse the same molded core  734  with redesigned PCBs  710  and  712 . This may decrease the cost in production or facilitate redesign of electrical devices based on older electrical devices, such as during version changes and/or upgrades. 
     In the described methods, a placement of a molding material between electrical components was discussed, such as in processes  750  and  758 . In some implementations, placement of molding may take place through introduction of a liquid resin and subsequent curing of the material. In these situations, the molding material injection may use the assistance of a receptacle to contain the liquid resin. In other implementations, a placement of a semi-solid material (e.g. paste) with posterior curing may be employed. Curing may take place through drying of a material, cross-linking of a polymer or any other appropriate method that produces a molding material that is an electrical insulator. In other processes, the molding material may be cast with a mold that accounts for electrical component placement. The cast may be generated and the electrical components may be disposed in the cast based on the desired arrangement of the electrical components. 
     As discussed above, the printed circuit board assemblies with molded core may facilitate the construction of shielding. The shielding assembly  800  illustrated in  FIG. 14  provides such a system. A bottom PCB  802  and a top PCB  804  may be affixed to a molded core  810 . The molded core  810  may have multiple electronic components (not illustrated) coupled to PCBs  802  and  804 , as discussed above. Furthermore, the bottom PCB  802  and the top PCB  804  may have multiple shielding pads  806 A and  806 B, respectively that may be formed through sputtering or some other deposition method. In some implementations, the shielding pads may be electrically coupled to a grounding layer. 
     The shielding pads  806 A of the bottom PCB  802  may be coupled to shielding pads  806 B of the top PCB  804  through thru-mold vias  808 . The thru-mold vias  808  may be produced through any of the previously discussed methods. The thru-mold vias  808  and the shielding pads  806 A and  806 B may form an electrical shielding to the electronic components within the shielding assembly  800 . This shielding may take place through a Faraday cage effect or some other effect on the emission of electromagnetic waves. The separation between the thru-mold vias  808  should be adjusted accordingly to the strength of the electrical field, the magnetic field, and/or expected electromagnetic emission frequencies of the electrical device. Note that the shielding assembly  800  may be restricted to a region of a printed circuit board assembly, leaving certain regions unshielded. For example, in an electrical device that has an electromagnetic shielding, based on a specification of the electrical device. 
     Technical advantages of the embodiments presented herein include but are not limited to the production and use of SIPs and printed circuit board assemblies that may improve the utilization of space within electrical devices. This may be accomplished by decreasing the amount of empty space (i.e., with no electrical component) along a direction perpendicular to a printed circuit board, which may be a product of connecting electronical components to multiple printed circuit boards. The increased component density may also be decrease bending and warping that may happen in printed circuit boards with uneven weight distribution. Moreover, the use of molding may improve mechanical properties of the printed circuit board assembly, improving the resilience of electrical devices to mechanical impacts or vibrations. 
     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.

Metadata:
Filing Date: 20160923
Publication Date: 20181113
Grant Date: 20181113
Priority Date: 20160923
Inventors: WANG, ALBERT
MARTINEZ, PAUL A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K3/341", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/0047", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/0707", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10734", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/4038", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/145", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/042", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0281", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/303", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10522", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/303", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0281", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/0707", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/0047", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10734", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09118", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/145", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/4046", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09118", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0278", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/4038", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/186", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/0707", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10522", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/042", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/341", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/4046", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0278", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/4614", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/186", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/4614", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61685980